Manuals and Guidelines for Micro-hydropower …gwweb.jica.go.jp/km/FSubject0901.nsf/8f7bda8fea534ade...Manuals and Guidelines for Micro-hydropower Development in Rural Electrification

DEPARTMENT OF ENERGY ENERGY UTILIZATION MANAGEMENT BUREAU

Manuals and Guidelines

for

Micro-hydropower Development

in Rural Electrification

Volume I

June 2009

Through the Project on “Sustainability Improvement of Renewable Energy Development for Village Electrification in the Philippines” under technical assistance of Japan International Cooperation Agency (JICA), this manual was developed by the Department of Energy (DOE) reviewing the “Manual for Micro-hydropower Development in March 2003.

Manuals and Guidelines

for Micro-hydropower Development in Rural Electrification

Volume I

MHP-1 Manual for Design, Implementation and Management for Micro-hydropower

Volume II

MHP-2 Guideline for Selection of Potential Sites and Rehabilitation Sites of Micro-hydropower

MHP-3 Project Evaluation Guideline for Micro-hydropower Development MHP-4 Micro-hydropower Plant Site Completion Test Manual MHP-5 Micro-hydropower Operator Training Manual MHP-6 Training Manual for Micro-hydropower Technology

１

DEPARTMENT OF ENERGY ENERGY UTILIZATION MANAGEMENT BUREAU

MANUAL

for

Design, Implementation and Management

For

Micro-hydropower Development

June 2009

MHP – 1

Through the Project on “Sustainability Improvement of Renewable Energy Development for Village Electrification in the Philippines” under technical assistance of Japan International Cooperation Agency (JICA), this manual was developed by the Department of Energy (DOE) reviewing the “Manual for Micro-hydropower Development in March 2003.

Manual for Micro-Hydro Power Development Contents

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Manual for Micro-Hydro Power Development

Table of Contents

EXECUTIVE SUMMARY

1 Background S-1

2 User of Manual S-1

3 Applicable Range of Micro-Hydropower S-1

4 How to use this Manual S-2

Chapter 1 INTRODUCTION 1-1

1.1 Purpose of the Manual for Micro-Hydro Development 1-1

1.2 Components of Micro-Hydro Power 1-2

1.3 Concept of Hydropower 1-5

1.4 The Water Cycle 1-7

Chapter 2 IDENTIFICATION OF THE POTENTIAL SITES 2-1

2.1 Basic Reference Materials 2-1

2.2 Radius of Site Identification 2-3

2.3 Calculation of River Flow 2-4

2.4 Identification of Potential Sites 2-5

2.4.1 Map Study 2-5

2.4.2 Identification Based on Local Information 2-6

2.4.3 Selection of Potential Development Sites 2-7

[Ref.2-1 Transmission and distribution line distance and voltage drop] 2-10

[Ref.2-2 Relationship between voltage drop and distribution line distance 2-11

[Ref.2-3 Considerations in the indirect estimation of discharge at the project

site using data from gauging stations in the vicinity. 2-12

[Ref.2-4 Method of river flow calculation by water balance model of

drainage area] 2-14

[Ref.2-5 Example of Micro-hydro Development Scheme Using Natural

Topography and Various Man-made Structures] 2-21

Chapter 3 SITE RECONNAISSANCE 3-1


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3.1 Objective of Site Reconnaissance 3-1

3.2 Preparation for Site Reconnaissance 3-1

3.2.1 Information gathering and preparation 3-1

3.2.2 Planning of preliminary site reconnaissance 3-2

3.2.3 Necessary equipment for preliminary site reconnaissance 3-2

3.3 Survey for Outline the Project Site 3-3

3.4 Validation of Geological Conditions Affecting Stability

of Main Civil Structures 3-5

3.5 Survey on Locations of Civil Structures 3-6

3.6 Measurement of River Flow 3-7

3.7 Measurement of Head 3-9

3.8 Demand Survey 3-10

3.8.1 Demand survey 3-10

3.8.2 Factors to consider in the Demand survey items 3-10

3.9 Actual Field Survey 3-12

[Ref.3-1 Method of Stream Flow Measurement] 3-13

[Ref.3-2 Method of Head Measurement] 3-18

[Ref.3-3 Sample Form Sheet for Potential Site Survey] 3-22

[Ref.3-4 Questionnaire for households of non-electrified barangays] 3-26

Chapter 4 PLANNING 4-1

4.1 Scheme of Development Layout 4-1

4.2 Data and Reference to Consider for Planning 4-3

4.2.1 Hydrograph and Flow Duration Curve 4-3

4.2.2 Plant Factor and Load Factor 4-4

4.3 Selection of Locations for Main Civil Structures 4-6

4.3.1 Location of Intake 4-6

4.3.2 Headrace Route 4-8

4.3.3 Location of Head Tank 4-8

4.3.4 Penstock Route 4-9

4.3.5 Location of Powerhouse 4-12

4.3.6 Location of Tailrace 4-13

4.4 Supply and Demand Plan 4-14

4.4.1 Selection of Power Demand Facilities 4-14


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4.4.2 Scheme of Development based on Supply and Demand 4-15

4.4.3 Daily Supply and Demand Plan 4-22

Chapter 5 DESIGN FOR CIVIL STRUCTURES 5-1

5.1 Basic Equation for Civil Design 5-1

5.2 Intake Weir (Dam) 5-1

5.2.1 Types of Intake Weir 5-1

5.2.2 Weir Height Calculation 5-5

5.3 Intake 5-9

5.3.1 Types of Intake 5-9

5.3.2 Important Points for Intake Design (for Side-Intake) 5-12

5.4 Settling basin 5-14

5.5 Headrace 5-17

5.5.1 Types and Structures of Headrace 5-17

5.5.2 Determining the Cross Section and Longitudinal Slope 5-21

5.6 Headtank 5-24

5.6.1 Headtank Capacity 5-24

5.6.2 Important Points for Headtank Design 5-26

5.7 Penstock 5-30

5.7.1 Penstock Material 5-30

5.7.2 Calculation of Steel Pipe Thickness 5-30

5.7.3 Determining Diameter of Penstock 5-30

5.8 Foundation of Powerhouse 5-34

5.8.1 Foundation for Impulse Turbine 5-34

5.8.2 Foundation for Reaction Turbine 5-35

[Ref. 5-1 Simple Method for Determining the Cross Section] 5-37

[Ref.5-2 Simple Method for Determining the Diameter of Penstock] 5-41

[Ref.5-3 Calculation of Head Loss] 5-42

Chapter 6 DESIGN FOR MECHANICAL AND ELECTRICAL STRUCTURES 6-1

6.1 Fundamental Equipment Components for Power Plant 6-1

6.2 Turbine (Water turbine) 6-5

6.2.1 Types and Output of Water Turbine 6-5

6.2.2 Specific Speed and Rotation Speed of Turbine 6-8


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6.2.3 Design of Crossflow Turbine 6-12

6.2.4 Design of Reverse Pump Type Turbine (Pump As Turbine) 6-13

6.3 Generator 6-14

6.3.1 Types of Generator 6-14

6.3.2 Output of Generator 6-16

6.3.3 Speed and Number of Poles of Generator 6-17

6.4 Power Transmission Facility (Speed Increaser) 6-19

6.5 Control Facility of Turbine and Generator 6-20

6.5.1 Speed Governor 6-20

6.5.2 Exciter of Generator 6-21

6.5.3 Single Line Diagram 6-23

6.6 Control, Instrumentation and Protection of Plant 6-24

6.6.1 Control Method of Plant 6-24

6.6.2 Instrumentation of Plant 6-24

6.6.3 Protection of Plant and 380/220V Distribution Line 6-25

6.6.4 Protection of 20kV Distribution Line 6-25

6.7 Inlet Valve 6-26

Annex 6.1 Brief Design of Cross Flow Turbine (SKAT T-12,13 & 14) 6-28

Annex 6.2 Brief Design of Reverse Pump Turbine (PAT) 6-33

Annex 6.3 Technical Application Sheet of Tender for

for Rural Electrification 6-46

Annex 6.4 Breif Design for Electro-mechanical Equipment of

Micro-hydropower Plant 6-49

Chapter 7 DESIGN OF DISTRIBUTION FACILITIES 7-1

7.1 Concept of Electricity 7-1

7.2 Selection for Distribution Route 7-3

7.3 Distribution Facilities 7-5

7.4 Pole 7-6

7.4.1 Span Length of Poles 7-6

7.4.2 Allowable Minimum Clearance of Conductors and Environment 7-7

7.4.3 Height of Poles 7-7

7.4.4 Size of Poles 7-8

7.5 Guy wire 7-9


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7.6 Conductors and Cables 7-12

7.6.1 Advantages/Disadvantages of Conductors and Cables 7-12

7.6.2 Sizes of Conductors 7-12

7.6.3 Allowable Sag of Conductors 7-12

7.6.4 Allowable Load per Phase 7-12

7.6.5 Application of 3-Phase Line 7-12

7.7 Distribution Transformers 7-13

7.7.1 Types of Distribution Transformer 7-13

7.7.2 Necessity of Transformers 7-14

7.7.3 Application of Distribution Transformers 7-15

7.7.4 Selection of Unit Capacity 7-15

7.7.5 Location 7-15

7.8 House Connection (HC) 7-16

7.8.1 Application of House Connection 7-16

7.8.2 In-house Wiring 7-17

[Ref.7-1 Standard of Steel poles] 7-18

[Ref.7-2 Construction of house connection crossing village road] 7-19

Chapter 8 PROJECT COST ESTIMATION 8-1

8.1 Rough Cost Estimation During Planning Stage 8-1

8.2 Cost Estimation During Detail Design Stage 8-3

8.2.1 Items 8-3

8.2.2 Quantity 8-5

8.2.3 Unit Cost 8-6

[ Ref. 8-1 Cross-sectional method to calculate quantity] 8-11

[Ref.8-2 Example of Bill of Quantities] 8-13

Chapter 9 CONSTRUCTION MANAGEMENT 9-1

9.1 Construction Management for Civil Facilities 9-1

9.1.1 Purpose 9-1

9.1.2 Progress Control 9-1

9.1.3 Dimension Control 9-2

9.1.4 Quality Control 9-3


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9.2 Construction Management for Turbine, Generator and

their Associated Equipment 9-5

9.2.1 Installation 9-5

9.2.2 Adjustment during Test Run Operation 9-6

Chapter 10 OPERATION AND MAINTENANCE 10-1

10.1 Introduction 10-1

10.2 Operation 10-2

10.2.1 Basic Operation 10-2

10.2.2 Operation in case of Emergency 10-4

10.2.3 Others 10-5

10.3 Maintenance 10-6

10.3.1 Daily Patrol 10-6

10.3.2 Periodic Inspection 10-8

10.3.3 Special Inspection 10-8

10.4 Recording 10-9

Chapter 11 MANAGEMENT 11-1

11.1 Establishment of Organization 11-1

11.2 Management System 11-1

11.3 Reporting and Monitoring 11-2

11.4 Decision-Making System 11-2

11.5 Accounting System 11-3

11.6 Roles and Responsibilities of BAPA 11-3

11.6.1 BAPA Officials 11-3

11.6.2 Consumers 11-5

11.6.3 Local Government Unit (LGU) 11-5

11.6.4 Department of Energy (DOE) 11-5

11.7 Training 11-5

11.8 Collection of Electricity Charges and Financial management 11-6

11.8.1 Tariff Setting 11-6

11.8.2 Tariff Collection 11-6

11.8.3 Financial Management 11-7

Manual for Micro-Hydro Power Development Executive Summary

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EXECUTIVE SUMMARY

1. Background

The first micro-hydropower plant was constructed in the 1930’s in San Pablo City,

Laguna Province. Although the Philippines has more than 60-year history in

micro-hydro development, most of the micro-hydropower plants, particularly those that

are recently installed, are not operational or have some problems in their operation.

Some identified issues or problems are the results of insufficient site assessment, poor

quality of power plant facilities and electro-mechanical equipment, and inadequate

operation and maintenance. In order to provide solution to these issues, as well as to

ensure sustainable development, it is required to use a guide and/or manual for

micro-hydro development.

This manual was provided as a technical supplement of the “Guide on Micro-hydro

Development for Rural Electrification” which was developed under JICA Expert

Dispatch Program for Rural Electrification utilizing Micro-hydro Technology.

2. User of Manual

This manual is intended to assist prospective micro-hydropower developers/proponents

for rural electrification in the off-grid and/or isolated barangays, such as local

government units (LGU’s), cooperatives and NGOs. This manual mainly deals with

technical aspects of micro-hydropower technology to facilitate the community based

micro-hydro development.

3. Applicable Range of Micro-Hydropower

The selection of best turbines depends on the site characteristics, the dominant factor on

the selection process being the head available and the power required. Selection also

depends on the speed at which it is desired to run the generator or other device loading

the turbine. It should be considered that whether or not the turbine will be expected to

produce power under part-flow conditions, also play an important role in the selection.

In the micro-hydropower scheme, turbines could be classified and grouped according to

operating principle as shown in the table below.


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Table S.1 Classification and applicability range of turbines HEAD (pressure) Turbine Type High < 40 m. Medium 20-40 m. Low 5-20 m.

Impulse Pelton

Turgo

Crossflow (Banki)

Turgo Pelton

Crossflow (Banki)

Reaction Francis Pump-as-turbine (PAT)

Kaplan Propeller

Propeller Kaplan

4. How to use this manual

This manual is composed of eleven (11) chapters in relation with the “Project Cycle of

Sustainable Rural Electrification by Utilizing Micro-Hydro Technology”.

The conduct of site assessment and investigation in the study for a proposed

micro-hydropower development are necessary to upgrade its level of accuracy. However,

high precision survey or detailed investigation for preliminary design during the

planning stage is not recommended due to practical and economic reasons. The

development scale of micro-hydro is small and the cost of survey work is relatively

high.

The stages of mini-hydropower development project cycle are as follows.

Project Planning Stage

Project Implementation Stage

Project Operation Stage

In the first stage of the project cycle, termed as the “Project Planning Stage, the major

activities are “Selection of Potential Sites”, “Site Reconnaissance”, “Planning of the

Potential Sites” and “Formulation of the Project Development Plan” in the target area

utilizing decentralized power generation. Several potential sites will be considered in

this stage in order to formulate the electrification plan for the whole target area. Chapter

3 through Chapter 4, Chapter 8-1 and Chapter 11 of this manual will comprise the

pre-implementation stage.


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Figure S.1 Flowchart of Micro-hydropower Development (DOE’s BEP Projects)

Community Dept. of Energy / Other Donors

Proponent (LGUs/NGOs)

List of

unenergized

sites identified

for NRE

Project

Op

eration Stage

Project Im

plem

entation

Stage P

roject Plan

nin

g Stage

Site Reconnaissance

Layout and Design

Mobilization

House wiring/Construction/ Installation

O & M Training

Monitoring and

Technical advice

for the Project Management and O & M of the project

LGU/NGO request Request for

consultant

Data Analysis

Commissioning

Data Collection

Technical

Assistance, if

necessary

Technical A i t

BAPA Formulation Approval

Proposal preparation

Periodic


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The second stage is the “Project Implementation Stage”. This stage covers the “Detail

Design” and “Construction” of the particular site. Chapter 5 through Chapter 9 of this

manual will be used in the project implementation stage.

The final stage is the “Project Operation Stage”. In this stage, “Operation and

Maintenance” and “Management” will be discussed. These activities are described in

Chapter 10 through Chapter 11 of this manual.

The descriptions in each chapter are follows,

Chapter 1 Introduction

Introduces the concept of the micro-hydropower.

Chapter 2 Selection of Potential Sites

Deals with the technical aspects for site selection on the topographical map and

local information.

Chapter 3 Site Reconnaissance

Provides procedural activities on how to conduct the survey on social condition

as well as technical aspects of the potential site that were revealed in the above

activities. In site reconnaissance, it is important to consider the possibility and

capacity of the power generation and the demand in the area concerned.

Chapter 4 Planning

Shows the technical aspects for the planning of the project as shown in Figure

S.2.

Chapter 5 Design of Civil Structures

The main problem for the development of a small-scale hydropower plant is the

high upfront cost. In this chapter, various techniques were described to possibly

reduce the construction cost of civil structures.

Chapter 6 Design of Mechanical and Electrical Structures

Provides the technical aspects for Mechanical and Electrical Structures such as

Inlet valve, Turbine and Generator.


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Figure S.2 Flowchart for the Planning of the Project

Chapter 7 Design of Distribution Facilities

Provides the technical aspects to be considered for Distribution Facilities such as

a pole, cable, and transformer.

Chapter 8 Project Cost Estimate

Shows example and formula of cost estimate per item of work. It also shows

Identification of System Layout

(refer to 4.1)

Confirmation of Design Discharge

(refer to 4.2)

Selection of the Civil Structures Location

(refer to 4.3)

Confirmation of the Head

(refer to Ref.5-3)

Selection of Power Demand Facilities

(refer to 4.4.1)Selection of the Generating System

Crossflow Turbine System or Pumps as Turbine System

Examination of Demand and Supply Balance

(Refer to 4.4.2)

Reconnaissance on Potential Site Reconnaissance on Demand Site

Site Reconnaissance

(Refer to Chapter 3)

Unbalanced Unbalanced

Rough Estimation of the Project Cost

(Refer to 8.1)

Balanced

Project Implementation Stage

:There are the description in Chapter 4


- S-6 -

how to calculate quantity per work item.

Chapter 9 Construction Management

Refers to the purpose of Construction Management. It also includes progress

control, dimension control and quality control.

Chapter 10 Operation and Maintenance

Shows the necessity of a manual for operation and maintenance and the

importance of daily and periodic inspection.

Chapter 11 Management

In this chapter, the importance of establishing an association in the barangay for

smooth performance in the management of the Micro-hydropower system was

clarified.

Manual for Micro-Hydro Power Development Chapter 1

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Chapter 1 INTRODUCTION

1.1 Purpose of the Manual for Micro-Hydro Development

Usually, Micro-Hydroelectric Power, or Micro-Hydro, are used in the rural

electrification and does not necessarily supply electricity to the national grid. They are

utilized in isolated and off-grid barangays for decentralized electrification.

There is an increasing need in many developing countries for rural electrification

purposely to provide illumination at night and to support livelihood projects. Also, the

government is faced with the high costs of extending electricity grids. Often,

Micro-Hydro system offers an economical option or alternative to grid extension. The

high cost of transmission lines and the very low load factor in the rural areas contributes

to the non-viability of the grid extension scheme. On the contrary, Micro-Hydro

schemes can be designed and built by the local people and smaller organizations

following less strict regulations and using local technology like traditional irrigation

facilities or locally fabricated turbines. This approach is termed as the Localized

Approach. Fig 1.1.1 illustrates the significance of this approach in lowering the

development cost of Micro-Hydro systems. It is hoped that this Manual will help to

promote the Localized Approach.

Fig 1.1.1 Micro-Hydro’s Economy of Scale ( based on 1985 data)


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1.2 Components of Micro-Hydro Power

Figure1.2.1 shows the major components of a typical micro-hydro development scheme.

Fig. 1.2.1 Major components of a micro-hydro scheme

- Diversion Weir and Intake

The diversion weir – a barrier built across the river used to divert water through an

opening in the riverside (the ‘Intake’ opening) into a settling basin.

- Settling Basin

The settling basin is used to trap sand or suspended silt from the water before

entering the penstock. It may be built at the intake or at the forebay.

Headtank Headrace


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- Headrace

A channel leading water to a forebay or turbine. The headrace follows the contour of

the hillside so as to preserve the elevation of the diverted water.

- Headtank

Pond at the top of a penstock or pipeline; serves as final settling basin, provides

submergence of penstock inlet and accommodation of trash rack and

overflow/spillway arrangement.


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- Penstock

A close conduit or pressure pipe for supplying water under pressure to a turbine.

- Water Turbine and Generator

A water turbine is a machine to directly convert the kinetic energy of the flowing

water into a useful rotational energy while a generator is a device used to convert

mechanical energy into electrical energy.

There are of course many variations on the design layout of the system. As an

example, the water is entered directly to the turbine from a channel without a

penstock. This type is the simplest method to get the waterpower. Another variation is

that the channel could be eliminated, and the penstock will run directly to the turbine.

Variations like this will depend on the characteristics of the particular site and the

requirements of the user of system.


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1.3 Concept of Hydro Power

A hydro scheme requires both water flow and a drop in height (referred to as ‘Head’) to

produce useful power. The power conversion absorbs power in the form of head and

flow, and delivering power in the form of electricity or mechanical shaft power. No

power conversion system can deliver as much useful power as it absorbs –some power

is lost by the system itself in the form of friction, heating, noise, etc.

The power conversion equation is :

Power input = Power output + Loss

or Power output = Power input × Conversion Efficiency

The power input, or total power absorbed by the hydro scheme, is the gross power,

(Pgross). The power output is the net power (Pnet). The overall efficiency of the scheme

(Fig.1.3.2) is termed Eo.

Pnet = Pgross ×Eo in kW

The gross power is the product of the gross head (Hgross), the design flow (Q) and a

coefficient factor (g = 9.8), so the fundamental hydropower equation is:

Fig. 1.3.1 Head is the vertical height through which the water drops


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Pnet = g ×Hgross × Q ×Eo kW (g=9.8)

where the gross head is in meters and the design flow is in cubic meter per second. Eo is

derived as follows:

Eo = Ecivil work ×Epenstock × Eturbine × Egenerator × Edrive system× Eline × Etransformer

Usually Ecivil work : 1.0 - (Channel length × 0.002 ～ 0.005)/ Hgross

Epenstock : 0.90 ～ 0.95 (it’s depends on length)

Eturbine : 0.70 ～ 0.85 (it’s depends on the type of turbine)

Egenerator : 0.80 ～ 0.95 (it’s depends on the capacity of generator)

Edrive system : 0.97

Eline : 0.90 ～ 0.98 (it’s depends on the transmission length)

Etransformer : 0.98

Ecivil work and Epenstock are usually computed as ‘Head Loss (Hloss)’. In this case, the

hydropower equation becomes:

Pnet= g ×(Hgross-Hloss) ×Q ×(Eo - Ecivil work - Epenstock ) kW

This simple equation should be memorized: it is the heart and soul of hydro power

design work.

Fig 1.3.2 Typical system efficiencies for a scheme running at full design flow.





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1.4 The Water Cycle

The volume of the river flow or discharge depends on the catchment area and the

volume of rainfall. Figure 1.4.1 shows how the rainfall is divided on both sides (A and

B) of the watershed. For example, there is an existing Hydropower Plant at A-side, the

rainfall at B-side cannot be used for power generation at this Hydropower Plant.

Therefore, the catchment area of a proposed hydropower plant should be known at the

first step of the study of hydro scheme.

Fig 1.4.1 The hydrological cycle

The broken lines in Fig 1.4.2 indicate the watershed of Point-A and Point-B. The

catchment area is the area enclosed by broken lines.

Fig 1.4.2 The catchment area and the watershed


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Chapter 2 IDENTIFICATION OF POTENTIAL SITES

It is necessary to roughly examine (i) whether or not the construction of a small-scale

hydropower plant near the power demand area is feasible and (ii) how much power

capacity can be generated sufficiently and where, and then (iii) how to select a potential

site among the candidate sites.

The initial examination is basically a desk study using available reference materials and

information and the procedure involved and important issues to be addressed are

explained below.

2.1 Basic Reference Materials

The basic reference materials required are the following:

1) Topographical map: scale: 1/50,000

Topographical map provides important information, such as landform, location of

communities, slope of the river, catchment area of proposed sites, access road, etc.

In the Philippines, topographical maps of scale 1/50,000 are available at the

National Mapping & Resources Information Authority (NAMRIA)

2) Rainfall data: isohyetal map and others (cf. Fig 2.1.1)

Although it is unnecessary to gather detailed rainfall data at this stage, it is

necessary to have a clear understanding of the rainfall characteristics of the project

area using an isohyetal map for the region and existing rainfall data for the

adjacent area. Isohyetal map provides the interpolation and averaging will give an

approximate indication of rainfall.


- 2-2 -

Figure 2.1.1 (a)

Fig 2.1.1(b) An example of isohyetal map for micro-hydro scheme


- 2-3 -

2.2 Radius of Site Identification

As most of the electric energy generated by a small-scale hydropower plant is basically

intended for the consumption of the target area, it is important to consider that the plant

site should be as nearer as possible to the load center. In the case of highly dispersed

communities, which are distributed over a relatively large area, it may be more

advantageous to construct individual micro-hydropower plants, rather than to supply

power to all groups by a single plant, due to lower transmission cost, easier operation

and maintenance and fewer impacts due to unexpected plant stoppage, etc. To be more

efficient in planning individual-type micro-hydropower plants, it is recommended to

gradually widen the scope of the survey, starting from the geographical area of each

group.

The transmission distance from the potential site to the target site should depend on

various parameters, the power output, demand level, topography, accessibility

conditions, transmission voltage and cost of transmission lines. In Japan, the

transmission distance to the demand site is set to ensure a voltage drop rate which does

not exceed 7%. [Reference 2-1: Transmission and distribution line distance and voltage

drop]

In case of Micro-hydro Scheme in the Philippines, the rough estimate for the maximum

allowable transmission distance is 1.5 kilometers (km) from the load center. This

distance is based on the premise that the voltage at the end of distribution line should be

kept at not less than 205 volts (V) or the permissible voltage drop is only 15V on the

regulated voltage of 220V, without using a transformer. [Reference 2-2 Relationship

between voltage drop and distribution line distance]

If a good potential site is not found within the above distance, the radius of

identification should be expanded over a larger area with the provision that the

transformer should be installed.


- 2-4 -

2.3 Calculation of River Flow

Among the river flow data mentioned earlier, historical records of flow data in the

area surrounding the project site should be used to estimate the river flow, taking the

rainfall distribution characteristics into consideration.

Qp = Rr×Qo／Ao

Where,

Qp : river flow per unit catchment area in project area (m3/s／km2)

Rr : rainfall ratio between catchment area of the proposed site for micro-hydro

project and of existing gauging station

Qo : observed river flow at existing gauging station or existing hydro-power station

(m3/s)

Ao : catchment area of existing gauging station (km2)

[See Reference 2-3: Considerations when estimating river flow at the project site

(indirectly from existing data of vicinity gauging stations) for the important points to

note for river flow based on the existing gauging station nearby.]

Particularly in the micro-hydro scheme, it is important to note that the firm discharge,

which is the flow during the driest time of the year, should be estimated accurately.

If no flow data is available, it is possible to estimate the rough flow duration curve

referring to “Reference 2-3: Simple calculating method of river flow by the water

balance model of drainage area”.


- 2-5 -

2.4 Identification of Potential Sites

2.4.1 Map Study

Potential sites are identified on the topographical map with a scale of 1/50,000 by

interpreting the head.

The following parameters should be considered in the map study:

(1) Site identification considering river gradient and catchment area

Sites with high head, shortest waterway and high discharge level are naturally

advantageous for hydropower generation.

The information on the river gradient (elevation difference and river length) and the

drainage area could be obtained in the map study. While some experience is required to

identify potential sites from a topographical map, if the diagrams shown Fig 2.4.1 are

prepared in advance for the subject river, the identification of potential sites is much

easier.

(2) Identification based on waterway construction conditions

As far as the basic layout of a micro-hydro scheme is concerned, most civil structures

are planned to have an exposed structure. Because of this, the topography at any

potential site must be able to accommodate such exposed civil structures. (Refer to

Chapter 4, 4.1 System Layout )


- 2-6 -

Fig 2.4.1 River Profile and Changes in Drainage Area of River to consider in the

Identification of Promising Sites for Hydropower Development

2.4.2 Identification Based on Local Information

In cases where potential sites cannot be interpreted on the topographical map because of

the small usable head or the presence of a fall or pool, etc. as well as existing

infrastructures like intake facilities for irrigation and forest roads, potential sites are

identified on the basis of information provided by a local public body and/or local

residents’ organization. [Reference 2-5: Example of Natural Topography and Various

Infrastructures]

Confluence

Suitable section for power E

leva

tion

C

atch

men

t A

rea

River

Change in Catchment Area

Distance


- 2-7 -

2.4.3 Selection of Potential Development Sites

The potential sites identified in the previously described study are then examined for

their suitability in hydropower development.

(1) Level of firm discharge

While it is difficult to judge the suitability for development based on the absolute

volume of firm discharge, a potential site with a relatively high level of firm discharge

is more favourable site for a micro-hydro plant designed to supply power throughout the

year.

Figure 2.4.2 shows the relation of specific firm discharge and the ratio of firm discharge

to maximum discharge (Qmax/QF: refer to the figure below) in existing small-scale

hydropower plants. Generally, the Qmax/QF values of micro hydropower plant for rural

electrification are shown about 1.0. This is meaning that the maximum discharges of

micro hydropower plants are the same as the firm discharge. This is because constant

electric power through a year is required to the micro hydropower plant for the rural

electrification program. And the specific firm discharge in the Qmax/QF range are

0.8~2.0 m3/s／100km2. The difference of vegetation of the catchment area and the

annual precipitation cause this difference. For the initial identification of potential site,

the maximum discharge/firm discharge will be set as 1.0 m3/s／100km2 . However,

the discharge set up in here should be reviewed at the time of site reconnaissance.

Qmax

Duration Curve

QF

Riv

erfl

ow(m

3 /s)

Days


- 2-8 -

Fig 2.4.2 Relationship between firm discharge/maximum discharge ratio

and specific firm discharge

(2) L/H [ratio between waterway length (L) and total head (H)]

A site with a smaller L/H value is more advantageous for small-scale hydropower.

Figure 2.4.3 shows the relation of the ratio between the total head (H) and the waterway

length (L) (L/H) among existing small-scale hydropower sites where the total head is

not less than 10 m (the minimum head which can be interpreted on an existing

topographical map). As clearly indicated in the figure, the L/H of existing sites is

generally not higher than 40 or is an average of 25.

Figure 2.4.4 shows the relation of firm discharge and L/H, the sites with smaller firm

discharge has smaller L/H. The L/H of sites with less than 0.2m3/s firm discharge is

approximately below 15.

Maximum and Firm Discharge in Hydropower Plant

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

0 10 20 30 40 50 60 70 80 90 100 110

Percentage of Firm/Maximum Discharge (%)

Un

it F

irm

Dis

cha

rge

(m3 /s

/10

0km

2 )

Large

SmallMini

Micro


- 2-9 -

Fig2.4.3 Relation between head and waterway length

Fig2.4.4 Relation between firm discharge and L/H

0

0.1

0.2

0.3

0.4

0.5

0 10 20 30 40 50

Waterway length / Head

( )

Fir

mdi

sch

arge

(m3 /

s)

Head and Waterway Length

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000

Waterway Length (m) L

Hea

d (m

) H

Micro L/H<25

Mini L/H<25

Small/Large L/H<50L/H=10

L/H=25

L/H=50

Manual for Micro-Hydro Power Development Chapter 2 (Reference)

- 2-10 -

[Ref. 2-1 Relationship between transmission line distance and voltage drop]

Per

mis

sibl

e vo

ltage

dro

p ra

tio

Voltage drop ratio (%)


Per

mis

sibl

e vo

ltage

dr

op r

atio

Dis

tanc

e (k

m)

Dis

tanc

e (k

m)

Rel

atio

n o

f tr

ansm

issi

on

lin

e d

ista

nce

an

d v

olt

age

dro

p I

11kV

, 300

kW

Alu

min

um

Co

nd

uct

or

Rel

atio

n o

f tr

ansm

issi

on

lin

e d

ista

nce

an

d v

olt

age

dro

p II

6.6k

V, 3

00kW

A

lum

inu

m C

on

du

cto

r

Dia

met

er o

f lin

e D

iam

eter

of l

ine


- 2-11 -

[Ref. 2-2 Relationship between distribution line distance and voltage drop]

Dis

tanc

e (m

)


Per

mis

sibl

e vo

ltage

dr

op r

atio

Rel

atio

n o

f tr

ansm

issi

on

lin

e d

ista

nce

an

d v

olt

age

dro

p II

I

400V

, 50k

W

Alu

min

um

Co

nd

uct

or

Dia

met

er o

f lin

e


- 2-12 -

Ref. 2-3 Considerations in the estimation of discharge at the project site using data from gauging stations in the

vicinity.

If there are multiple gauging stations near the project site, the following parameters should be considered in

selecting the gauging station to be used.

1. Drainage Area Ratio

In estimating the discharge based on data of existing gauging stations, the drainage area should be taken into

consideration. From the discharge characteristic curve, as shown in the following figure, and drainage area

ratio between existing gauging station and project site is large, the flow duration curves may be crossing

each other which will make the discharge computation is unreliable.

2. Rainfall

The flow-duration and the rainfall characteristic in the upper portion of the river that has close correlation

with the long term discharge must be regarded as close correlation between rainfall and discharge. The

available rainfall data from gauging stations in both small and large drainage areas are useful information to

evaluate the discharge at the project site.

The simplest method in estimating the rainfall around the project site is to use the isohyetal maps. This map

shows contour lines of average rainfall, and can be compared to the amount of rainfall in the project site and

the gauging station.

Large drainage area

Day

Spe

cifi

c dr

aina

ge a

rea

Small drainage area

Big amount of rainfall

Small amount of rainfall

Day

Spe

cifi

c dr

aina

ge a

rea


- 2-13 -

3. Geological conditions

The evaluation of the discharge in the project site based on the presence of gauging stations in the area is not

enough to establish the correlation of flow duration curves. Geological condition also influenced the

similarity of flow duration curves aside from the drainage areas such as the existence of quaternary volcanic

rock area.

A quaternary volcanic rock is considered to have high water retention capability. Flow duration curves

influenced by this type of geology is relatively flat, wherein the discharge in wet season is only slightly

higher during the dry season, as compared with the flow duration curves of those that are not influenced by

this type of rocks, as shown in the figure below:

It is possible to know the distribution of quaternary volcanic rocks from existing geological map, however, it

is difficult to analyze quantitatively its share in the drainage area and the characteristic or general pattern of

discharge. Therefore, when quaternary volcanic rocks in the project area exists, it is recommended to select

gauging stations with equivalent geological characteristic.

Aside from the quaternary volcanic rock, limestone also affects the runoff and the river discharge. It is also

very difficult to measure its influence qualitatively and quantitatively. Generally the river with limestone

shows irregular discharge. Therefore, in case the drainage or catchment area is characterized with limestone

formation, it is suggested to conduct the stream flow measurement at the intake point of the project site.

4. Geographical condition

Geographical condition is also considered to have a significant influence in the estimation of discharge.

Generally, it is recognized that the amount of rainfall is larger at higher altitude and steeper mountain. Hence,

selection of gauging stations with similar geographical conditions, such as altitude, features, and direction of

drainage area is considered as one of the methods that raise the accuracy of discharge estimation.

In case no dissecting plain exist in the drainage area of the project site and its outline falls down, the runoff

may flow out of the drainage area through seepage.

Existence of Quaternaryvolcanic rock in the drainage area

Day

Spe

cifi

c dr

aina

ge a

rea

Not existence of Quaternary volcanic rock


- 2-14 -

[Ref. 2-4 Method of river flow by the water balance model of drainage area]

If there are no discharge observation data and only rainfall data is available, it is possible to estimate river

discharge from the water balance data of the drainage area.

1. Calculation method

(1) Water balance of the drainage area

The relation of rainfall, runoff (direct runoff, base runoff), and evaporation is indicated by the viewpoint of

annual water balance as shown in the formula below. In this case, pooling of drainage area and inflow and

runoff from/to other drainage area are not necessary.

P = R + Et

= Rd + Rb + Et

where,

P : Annual rainfall (mm)

R : Annual runoff (mm)

Rd : Annual direct runoff (mm)

Rb : Annual base runoff (mm)

Et : Annual evaporation (mm)

Runoff (R) is obtained from calculated evaporation (Et) by the presumption formula and observed rainfall

(P).

A pattern figure of the relation of rainfall (R), possible evaporation (Etp), and real evaporation (Et) is shown

Figure 1-1. Indicated as diagonal line is real evaporation, and area above line b-c is river runoff including

sub-surface water. Possible evaporation (a-b-c-d) is obtained by presumption formula.

(2) Direct runoff and base runoff

A pattern of annual runoff is shown Figure 1-2. The runoff is provided from sub-surface water, and it

contained base runoff with less seasonal fluctuation and direct runoff wherein the rainfall immediately

becomes the runoff. The ratio of sub-surface water to annual runoff (R) is shown in Table 1-1. Where, Rg = Rb,

Rb / R = 0.25 constant, and the base runoff is taken as constant.


- 2-15 -

Figure 1-1 Pattern figure of amount of rainfall and evaporation

Figure 1-2 Pattern figure of runoff

Amount of rainfall

Amount of real evaporation (Et)

Possible evaporation (Etp) Runoff (R)

Am

ount

of

rain

fall

, eva

pora

tion

(m

m)

Month

Am

ount

of

runo

ff (

m3 /s

)

Month

Amount of direct runoff

Amount of base runoff


- 2-16 -

Table 1-1 World water balance model

(Note) Source: Lvovich 1973

Data of Japan from Ministry of Land, Infrastructure and Transport

(3) Calculation of possible evaporation

The calculation formulas are Blaney-Criddle formula, Penman formula, and Thornthwaite formula etc. Herein,

Blaney-Criddle formula was used which is the simplest method using the longitude and temperature of the

project site. The observed value of evaporation from free water surface was also considered.

(a) Calculation method

① Blaney-Criddle formula

where,

u : Monthly evaporation (mm)

K : Monthly coefficient of vegetation

P : Monthly rate of annual sunshine (%)

t : Monthly average temperature (℃)

② Monthly average temperature and monthly rate of annual sunshine

・Monthly average temperature ; Using temperature at the drainage area of dam site

・Monthly rate of annual sunshine ; Obtained by the latitude at the drainage area of dam site

In the northern hemisphere, use Table 1-2, and in the southern hemisphere, use Table 1-3.

③ K value depends on the vegetation condition. Herein, a constant of 0.6 was used.

(b) Example of calculation

① Conditions : Position of drainage area lat. 16゜N

② Calculation of possible evaporation : Table 1-4

u = K・P・ 100

( 45.7t + 813 )

Area Asia Africa North America South America Europe Australia JapanRainfall(P) 726 686 670 1648 734 736 1788Runoff(R) 293 139 287 583 319 226 1197 Direct runoff (Rd) 217 91 203 373 210 172 - Subsoilwater 76 48 84 210 109 54 -Evaporation(Et) 433 547 383 1065 415 510 597

Rg / R 26 35 32 36 34 24 -


- 2-17 -

(4) Calculation of evaporation

It is shown in Table 1-4, the monthly evaporations are obtained by lower value of rainfall or possible

evaporation.

(5) Computation of monthly runoff data

a) Computation by the procedure shown in Table 1-5.

b) Derivation of the monthly mean discharge data at the dam site by the following formula.

where,

Q (i) : Monthly mean discharge at dam site in ‘i (month)’ (m3/s)

CA : Drainage area (km2)

n : Number of days in the month

The discharge for the drainage area of 300 km2 is shown in Table 1-5.

In addition, the ratio of the base runoff to the total runoff (25%) and the monthly distribution of base

runoff (constant) can be analyzed with regards to the characteristic of runoff at the area.

Q (i) = ×CA×106× 1000 86,400×n

Monthly runoff (④of Table 1-5 ) 1


- 2-18 -

Table 1-2 Monthly rate of annual sunshine (Northern Hemisphere) (%)

North Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

Latitude

65 3.52 5.13 7.96 9.97 12.72 14.15 13.59 11.18 8.55 6.53 4.08 2.6264 3.81 5.27 8.00 9.92 12.50 13.63 13.26 11.08 8.56 6.63 4.32 3.0263 4.07 5.39 8.04 9.86 12.29 13.24 12.97 10.97 8.56 6.73 4.52 3.3662 4.31 5.49 8.07 9.80 12.11 12.92 12.73 10.87 8.55 6.80 4.70 3.6561 4.51 5.58 8.09 9.74 11.94 12.66 12.51 10.77 8.55 6.88 4.86 3.91

60 4.70 5.67 8.11 9.69 11.78 12.41 12.31 10.68 8.54 6.95 5.02 4.1459 4.86 5.76 8.13 9.64 11.64 12.19 12.13 10.60 8.53 7.00 5.17 4.3558 5.02 5.84 8.14 9.59 11.50 12.00 11.96 10.52 8.53 7.06 5.30 4.5457 5.17 5.91 8.15 9.53 11.38 11.83 11.81 10.44 8.52 7.13 5.42 4.7156 5.31 5.98 8.17 9.48 11.26 11.68 11.67 10.36 8.52 7.18 5.52 4.87

55 5.44 6.04 8.18 9.44 11.15 11.53 11.54 10.29 8.51 7.23 5.63 5.0254 5.56 6.10 8.19 9.40 11.04 11.39 11.42 10.22 8.50 7.28 5.74 5.1653 5.68 6.16 8.20 9.36 10.94 11.26 11.30 10.16 8.49 7.32 5.83 5.3052 5.79 6.22 8.21 9.32 10.85 11.14 11.19 10.10 8.48 7.36 5.92 5.4251 5.89 6.27 8.23 9.28 10.76 11.02 11.09 10.05 8.47 7.40 6.00 5.54

50 5.99 6.32 8.24 9.24 10.68 10.92 10.99 9.99 8.46 7.44 6.08 5.6548 6.17 6.41 8.26 9.17 10.52 10.72 10.81 9.89 8.45 7.51 6.24 5.8546 6.33 6.50 8.28 9.11 10.38 10.53 10.65 9.79 8.43 7.58 6.37 6.0544 6.48 6.57 8.29 9.05 10.25 10.39 10.49 9.71 8.41 7.64 6.50 6.2242 6.61 6.65 8.30 8.99 10.13 10.24 10.35 9.62 8.40 7.70 6.62 6.39

40 6.75 6.72 8.32 8.93 10.01 10.09 10.22 9.55 8.39 7.75 6.73 6.5438 6.87 6.79 8.33 8.89 9.90 9.96 10.11 9.47 8.37 7.80 6.83 6.6836 6.98 6.85 8.35 8.85 9.80 9.82 9.99 9.41 8.36 7.85 6.93 6.8134 7.10 6.91 8.35 8.80 9.71 9.71 9.88 9.34 8.35 7.90 7.02 6.9332 7.20 6.97 8.36 8.75 9.62 9.60 9.77 9.28 8.34 7.95 7.11 7.05

30 7.31 7.02 8.37 8.71 9.54 9.49 9.67 9.21 8.33 7.99 7.20 7.1628 7.40 7.07 8.37 8.67 9.46 9.39 9.58 9.17 8.32 8.02 7.28 7.2726 7.49 7.12 8.38 8.64 9.37 9.29 9.49 9.11 8.32 8.06 7.36 7.3724 7.58 7.16 8.39 8.60 9.30 9.19 9.40 9.06 8.31 8.10 7.44 7.4722 7.67 7.21 8.40 8.56 9.22 9.11 9.32 9.01 8.30 8.13 7.51 7.56

20 7.75 7.26 8.41 8.53 9.15 9.02 9.24 8.95 8.29 8.17 7.58 7.6518 7.83 7.31 8.41 8.50 9.08 8.93 9.16 8.90 8.29 8.20 7.65 7.7416 7.91 7.35 8.42 8.47 9.01 8.85 9.08 8.85 8.28 8.23 7.72 7.8314 7.98 7.39 8.43 8.43 8.94 8.77 9.00 8.80 8.27 8.27 7.79 7.9312 8.06 7.43 8.44 8.40 8.87 8.69 8.92 8.76 8.26 8.31 7.85 8.01

10 8.14 7.47 8.45 8.37 8.81 8.61 8.85 8.71 8.25 8.34 7.91 8.098 8.21 7.51 8.45 8.34 8.74 8.53 8.78 8.66 8.25 8.37 7.98 8.186 8.28 7.55 8.46 8.31 8.68 8.45 8.71 8.62 8.24 8.40 8.04 8.264 8.36 7.59 8.47 8.28 8.62 8.37 8.64 8.58 8.23 8.43 8.10 8.342 8.43 7.63 8.49 8.25 8.55 8.29 8.57 8.53 8.22 8.46 8.16 8.42

0 8.50 7.67 8.49 8.22 8.49 8.22 8.50 8.49 8.21 8.49 8.22 8.50


- 2-19 -

Table 1-3 Monthly rate of annual sunshine (Southern Hemisphere) (%)

(Note) Southern part more than lat. 50°S will be calculated using example from Table 1-2. Concretely,

the monthly rate of southern latitude is corresponding to below showing months of northern

latitude.

Southern lat. - Northern lat. Southern lat. - Northern lat.

January - July July - January

February - August August - February

March - September September - March

April - October October - April

May - November November - May

June - December December - June

South Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.Latitude

0 8.50 7.67 8.49 8.22 8.49 8.22 8.50 8.49 8.21 8.49 8.22 8.502 8.55 7.71 8.49 8.19 8.44 8.17 8.43 8.44 8.20 8.52 8.27 8.554 8.64 7.76 8.50 8.17 8.39 8.08 8.20 8.41 8.19 8.56 8.33 8.656 8.71 7.81 8.50 8.12 8.30 8.00 8.19 8.37 8.18 8.59 8.38 8.748 8.79 7.84 8.51 8.11 8.24 7.91 8.13 8.12 8.18 8.62 8.47 8.84

10 8.85 7.86 8.52 8.09 8.18 7.84 8.11 8.28 8.18 8.65 8.52 8.9012 8.91 7.91 8.53 8.06 8.15 7.79 8.08 8.23 8.17 8.67 8.58 8.9514 8.97 7.97 8.54 8.03 8.07 7.70 7.08 8.19 8.16 8.69 8.65 9.0116 9.09 8.02 8.56 7.98 7.96 7.57 7.94 8.14 8.14 8.78 8.72 9.1718 9.18 8.06 8.57 7.93 7.89 7.50 7.88 8.10 8.14 8.80 8.80 9.24

20 9.25 8.09 8.58 7.92 7.83 7.41 7.73 8.05 8.13 8.83 8.85 9.3222 9.36 8.12 8.58 7.89 7.74 7.30 7.76 8.00 8.13 8.86 8.90 9.3824 9.44 8.17 8.59 7.87 7.65 7.24 7.68 7.95 8.12 8.89 8.96 9.4726 9.52 8.28 8.60 7.81 7.56 7.07 7.49 7.90 8.11 8.94 9.10 9.6128 9.61 8.31 8.61 7.79 7.49 6.99 7.40 7.85 8.10 8.97 9.19 9.74

30 9.69 8.33 8.63 7.75 7.43 6.94 7.30 7.80 8.09 9.00 9.24 9.8032 9.76 8.36 8.64 7.70 7.34 6.85 7.20 7.73 8.08 9.04 9.31 9.8734 9.88 8.41 8.65 7.68 7.25 6.73 7.10 7.69 8.06 9.07 9.38 9.9936 10.06 8.53 8.67 7.61 7.16 6.59 6.99 7.59 8.06 9.15 9.51 10.2138 10.14 8.61 8.68 7.59 7.07 6.46 6.87 7.51 8.05 9.19 9.60 10.34

40 10.24 8.65 8.70 7.54 6.96 6.33 6.73 7.46 8.04 9.23 9.69 10.4242 10.39 8.72 8.71 7.49 6.85 6.20 6.60 7.39 8.01 9.27 9.79 10.5744 10.52 8.81 8.72 7.44 6.73 6.04 6.45 7.30 8.00 9.34 9.91 10.7246 10.68 8.88 8.73 7.39 6.61 5.87 6.30 7.21 7.98 9.41 10.03 10.9048 10.85 8.98 8.76 7.32 6.45 5.69 6.13 7.12 7.96 9.47 10.17 11.09

50 11.03 9.06 8.77 7.25 6.31 5.48 5.98 7.03 7.95 9.53 10.32 11.30


- 2-20 -

Table 1-4 Calculation example of possible evaporation and real evaporation

(Note) ①: obtained data ②: from Table 1-2 ③: parenthetic numbers are observed evaporation value

from water surface

Table 1-5 Calculation example of river flow

(Note) ③Base runoff: distribute uniformity 434.3×0.25 = 108.6 mm to each month

①Temperature ②Monthly rate ofannual sunshine

④Rainfall ⑤Realevaporation

Month t psmaller valueof ③ and ④

(℃) (%) (mm) (mm)

Jan. 22.1 7.91 86.4 ( 91.0 ) 8.5 8.5Feb. 24.7 7.35 85.6 ( 106.4 ) 16.8 16.8Mar. 27.2 8.42 103.8 ( 129.7 ) 38.3 38.3Apr. 28.9 8.47 108.4 ( 138.2 ) 62.3 62.3May 28.4 9.01 114.2 ( 116.3 ) 170.0 114.2Jun. 27.7 8.85 110.4 ( 91.1 ) 180.3 110.4Jul. 27.1 9.08 111.8 ( 81.2 ) 202.9 111.8Aug. 27.0 8.85 108.7 ( 72.7 ) 197.7 108.7Sep. 27.1 8.28 101.9 ( 74.6 ) 207.7 101.9Oct. 26.5 8.23 100.0 ( 79.7 ) 123.0 100.0Nov. 24.1 7.72 88.6 ( 73.4 ) 30.2 30.2Dec. 22.0 7.83 85.4 ( 80.2 ) 17.9 17.9

Total 1,205.2 ( 1,134.5 ) 1,255.6 821.0

③Possible evaporation

from Blaney-Criddleformula

(mm)

①Runoff ②Direct runoff ③Base runoff ④Monthly runoff

Month④-⑤of Chart 1-4 ①×0.75 (Note) ②+③

(mm) (mm) (mm) (mm) (m3/s)

Jan. 0 0 9.2 9.2 1.03Feb. 0 0 8.3 8.3 1.03Mar. 0 0 9.2 9.2 1.03Apr. 0 0 8.9 8.9 1.03May 55.8 41.9 9.2 51.1 5.72Jun. 69.6 52.2 8.9 61.1 7.07Jul. 91.1 68.3 9.2 77.5 8.69Aug. 89.0 66.8 9.2 76.0 8.51Sep. 105.8 79.4 8.9 88.3 10.22Oct. 23.0 17.3 9.2 26.5 2.96Nov. 0 0 8.9 8.9 1.03Dec. 0 0 9.2 9.2 1.03

Total 434.3 325.7 108.6 434.3

⑤Monthlymeandischarge


- 2-21 -

[Ref. 2-5 Example of Micro-hydro Development Scheme Using Natural Topography and Various Man-Made

Structures]

1. Using existing irrigation channel and naturally formed pool downstream of fall

River

Headrace

River

Power house

Penstock Spillway

Irrigation channel Headtank Screen

Intake weir

Water fall


- 2-22 -

2. Intake water from two rivers

Ⅱ-2-5入る

Headrace

Intake weir

River

Intake weir

HeadtankScreen

Penstock

Power houseTailrace

River


- 2-23 -

3. Using a head drop structure of existing irrigation channel

Ⅱ-2-6入る

Intake

Headtank

Irrigation channel

Head drop structure

Penstock

Power house


- 2-24 -

4. Using a head drop structure of existing irrigation channel

Ⅱ-2-7入る

River

Intake

Headrace

Road Irrigation channel

Headtank

Penstock

Power house

Tailrace


- 3-1 -

CHAPTER 3 SITE RECONNAISSANCE

3.1 Objective of Site Reconnaissance

The objective of site reconnaissance for micro-hydro is to investigate potential sites and

supply area in order to evaluate the feasibility of projects and get information for

electrification planning. One of the most important activities in site reconnaissance is to

measure water discharge and head that could be utilized for micro-hydropower

generation. Investigations of intake site, waterway route, powerhouse site and

transmission route etc. are also conducted to assess the feasibility of project sites.

Power demand survey is also important in the planning of the electrification system.

Socio-economic data such as number of households and public facilities in supply area,

availability of local industries which will use electricity, solvency of local people for

electricity and the acceptability of local people to the electrification scheme are

gathered during the reconnaissance survey.

3.2 Preparation for Site Reconnaissance

To achieve effective and fruitful site reconnaissance, it is important to prepare for site

reconnaissance such as gathering of available information, devise sufficient plan and

schedule of survey activities in advance.

3.2.1 Information gathering and preparation

As advance information, 1/50,000 topographic maps are prepared to check the

topography of the target site and villages, the catchment area, village’s distribution and

access road. More accurate information on site accessibility could be collected by

contacting local people concerned.

Copies of 1/50,000 topographic maps and route maps enlarged by 200 to 400% are

prepared for the fieldwork.

Check list and interview sheet are also prepared for each site reconnaissance.


- 3-2 -

3.2.2 Planning of preliminary site reconnaissance

Although it may be required to deviate from original plan and schedule in accordance

with site condition, it is important to make sufficient plan and schedule for site

reconnaissance activities in advance. It is also necessary to coordinate with local

officials concerned to insure safety and successful conduct of the reconnaissance

activities. Since most of micro-hydro sites are located in mountainous and isolated areas,

it requires longer time to conduct site reconnaissance activities. Therefore, sufficient

schedule should be considered to have enough time for the fieldwork. Also,

measurement and other activities for site reconnaissance should be taken into account. A

check list or interview sheet should be prepared beforehand to efficiently perform

necessary activities of site reconnaissance.

3.2.3 Necessary equipment for preliminary site reconnaissance

Necessary equipment for preliminary site reconnaissance depends on purpose and

accuracy and site condition. Basic equipment is as follows:

Table 3.2.1 Check sheet of basic equipment for site reconnaissance as an example

Equipment Equipment

○ Route map ○ Altimeter

○ Topographic map ○ GPS (portable type)

○ Reconnaissance schedule ○ Camera, Film

○ Check list ○ Current meter

○ Interview sheet ○ Distance meter, measuring tape

Geological map ○ Hand level

Aerial photograph ○ Convex scale (2-3m)

Related reports Hammer

Map

, She

et

Clinometer

○ Field notebook Knife

○ Scale Scoop

○ Pencil ○ Torch, Flashlight

○ Eraser Sampling baggage

○ Color pencil Label

Section paper ○ Compass

Stop watch

Stat

iona

ry

Equ

ipm

ent

Battery

Notes: ○: necessary equipment for preliminary site reconnaissance


- 3-3 -

3.3 Survey to Outline the Project Site

During the reconnaissance at the proposed site of power generating facilities and around

the power demand area, a survey is conducted on the following items:

(1) Access conditions

The equipment and machinery used for the construction and operation of a micro-

hydropower plant are smaller and lighter than those used for an ordinary hydropower

plant and it may be possible in some cases that such equipment and machinery can be

brought to the site either manually or using simple vehicles.

Given the smaller capacity of the power generated by a micro-hydropower plant, careful

consideration is required in the use of transportation method and access other than the

use of an existing road or vehicle since the construction of a new access road could be a

factor that would considerably reduces the economy of a project. In the case of a

mountainous area, there may be an abandoned road (previously used for the hauling of

cut trees, etc.) which is difficult to find because it has been covered by vegetation and it

is important to interview local residents on the existence of such a road.

(2) Situation of existing system and future plan

Even for a project site in which the development of an individual system is assumed, a

survey should be conducted on the tail end location, route and voltage, etc. of the

existing system and also on the availability of extension and rehabilitation plans for the

said system.

(3) Situation of river water utilization

The existence of facilities utilizing the river flow, the flow volume and any relevant

future plans regarding the river from which a planned micro-hydropower plant will

draw water should also be surveyed. At the project formulation stage, the situation of

the portion or section of the river for water utilization should be surveyed taking into

consideration the assumed recession section and the possibility of changes in the

position of the intake and the waterway route.

When a fall or steep valley is to be used for power generation, local information on the

use of such a fall or valley should be obtained together with a survey on the relevant

legal regulations.


- 3-4 -

(4) Existence of other development plans/projects

A survey should be conducted on the existence of other development plans/projects in

terms of roads, farmland, housing and tourism, etc. which may affect the planned

project site and/or its surrounding area.

(5) Civil structures in adjacent area and materials used

Most civil structures of a small-scale hydropower plant are similar to those of irrigation

facilities and road drainage facilities. The materials used for these structurers are often

available or can be obtained near the planned project site.

The use of constructors, human resources and local materials involved in these civil

structures is important from the viewpoint of reducing the construction cost,

contribution to the local economy and ensuring easy maintenance and repair. Hence, a

survey should be conducted on similar civil structures in the adjacent area of a project

site to obtain useful reference materials for project planning and design.

(6) Presence of natural topographical features and existing structures usable for power

generation

When an existing irrigation channel or similar is used (including widening and/or

reinforcement) as a waterway for power station, it is necessary to check the

cross-section, gradient and current water conveyance volume, etc. of such a channel.

(7) Existence of important ground features and vegetation

Even a small-scale hydropower plant necessitates some alteration of the local

topography. When important ground features and/or vegetation exist along the planned

route of the waterway, they must be carefully dealt with. For this purpose, their

locations and conditions, etc. should be duly noted for discussions with concerned

parties such as the landowner(s) and representatives of the local government.


- 3-5 -

3.4 Validation of Geological Conditions Affecting Stability for Main Civil

Structures

The survey on the ground stability, especially that of the surface layer, is required for

the construction of a small-scale hydropower plant due to (i) the exposed structure of

most of the main civil structures and (ii) the rooting of the waterway on a sloping

hillside. The results of investigation should be presented in the form of sketch drawings

(refer to Fig 3.4.1) for reference purposes when determining the basic structures for

civil works.

Fig.3.4.1 A geological sketch based on site observations


- 3-6 -

3.5 Survey on Locations of Civil Structures

Field reconnaissance by the hydropower specialist is important to establish a waterway

route based on an existing topographical map and other relevant information for the

planning of a micro-hydropower plant. The results of the reconnaissance survey will

determine if the project will proceed or not.

The items to be checked during this survey are listed below. It is necessary to repeat the

field reconnaissance in line with the progress of the planning and design. When

uncertainties emerge, particularly at the design stage, field verification is necessary.

Moreover, there is a need to keep the expected demand in mind. Therefore, this survey

should be conducted in parallel with the demand survey.

It is important not only to select suitable locations for such individual facilities as the

intake weir and waterway, etc. but also to carefully examine the locations of their tie-in

sites.

For the development of micro-hydro, the maximum use of natural topographical

features is important from the viewpoint of cost reduction. It is, therefore, necessary to

conduct the survey based on a full understanding of the items discussed in “Chapter

4,4.3 Selection of Location for Main Civil Structures”.


- 3-7 -

3.6 Measurement of River Flow

(1) Necessity of Measurement of River Flow

(2)

The estimated river flow at a project site is considered reasonably reliable if it is based

on data from a nearby gauging station. As such, it may not be necessary to conduct

actual discharge measurement at the project site.

However, when river flow data is difficult to obtain, it is preferable to measure the river

discharge in the dry season, by means of simple method, to confirm the appropriateness

of the estimated flow duration. Any stoppage of power generation due to a reduced

water flow volume significantly affects the generation of a micro-hydropower plant,

thus it is essential to check the discharge at dry season. Although it is necessary to

record the river flow for at least one year in mini hydropower development, the river

flow during the dry season should be checked even for micro hydropower development.

Fig.3.4.2 shows the Flowchart to check Minimum Flow/ Duration Curve.

Should there be a need to measure the discharge, the observation period must be

carefully determined based on past rainfall records and information relative to the

climate.

It is also necessary to check and evaluate the observation results in connection with the

characteristics (for example, drought year or wet year) of the year of observation based

on past rainfall records, etc.

The stream flow measuring method, frequency and water level observation unit can be

simplified in the following manner to reduce the survey cost.


- 3-8 -

Water Level DischargeH Q

(m) (m3/s)

XXX 0.230 0.111YYY 0.550 1.734ZZZ 0.300 0.272

WWW 0.380 0.600

Date

Installation of Staff Gauge(Base Point)

Selection of MeasurementPoint

Measuring of Cross Section

Measuring of Cross SectionalArea(A)

Measuring of Velocity /Speed(V)

Calculation of Discharge(Q=A x V)

Record the water levelon Staff gauge (H)

An

oth

er d

ayat

leas

t 3

tim

esre

pea

t

DailyRecord

(Hd)

Calculation of Rating Curve

Calculation of DailyDischarge

Calculation of DurationCurve

Micro-Hydro

1

2

3

4

5

Staff Gauge

Rating Curve

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00

Discharge (m3/s)

Wat

er L

evel

(m)

Q=9.579*H2-2.428H+0.154

Discharge of Ambangal Brook at Intake (20.2km2)

0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.0

5/19/06 6/18/06 7/18/06 8/17/06 9/16/06 10/16/06 11/15/06 12/15/06 1/14/07 2/13/07 3/15/07 4/14/07 5/14/07 6/13/07 7/13/07

Date

Dis

char

ge (m

3/s

)

Daily DischargeDischarge of Ambangal Brook at Intake (20.2km2)

0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.0

5/19/06 6/18/06 7/18/06 8/17/06 9/16/06 10/16/06 11/15/06 12/15/06 1/14/07 2/13/07 3/15/07 4/14/07 5/14/07 6/13/07 7/13/07

Date

Dis

char

ge (m

3/s

)

Daily Discharge

Duration Curve at Intake Site (C.A.=20.2km2)

0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.0

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Percentage (%)

Dis

char

ge (m

3/s

)

Fig.3.4.2 Flowchart to check Minimum Flow/ Duration Curve


- 3-9 -

(2) Flow measuring method A stream flow measuring method which is appropriate for the river conditions can be adopted. [Reference 3-1: Simple method of stream flow measuring] (3) Frequency of stream flow measuring In principle, stream flow measuring should be conducted at least three times a year to analyze the relation between the water level and the discharge in the range below the assumed maximum discharge. (4) Water level observation unit A staff gauge should be set up at a point near the flow observation point where visual water level observation can be easily carried out. 3.7 Measurement of Head The head between the intake point and the headtank and the head between the headtank and the outlet point should be measured. At the initial planning stage, however, it may be sufficient to measure the head between the planned headtank location and the outlet level. While a surveying level can be used for the purpose of measuring, a more simple head measuring method may be sufficient. [Reference 3-2: Simple methods of head measuring]


- 3-10 -

3.8 Demand Survey 3.8.1 Demand survey method There can be many types of power demand facilities for small-scale hydropower generation to respond to the conditions of the subject area for development. In the preparation of development plan, accurate understanding of the power demand facilities in the subject area for development is essential. What is important is to ensure the efficiency and practicality of a demand survey. It is necessary to estimate a slightly higher demand level than the assumed scale of power generation so that it would adequately respond to the scale of development as well as to the seasonal fluctuations of the power demand. 3.8.2 Factors to consider in demand survey The demand survey items are described below. When there is more than one power demand facility, each facility should be survey. (1) Location The suitable route and distance, etc. to each power demand facility should be surveyed to examine the optimal transmission and distribution lines. (2) Owners The opinions and intentions of the owners of power demand facilities regarding the introduction of a new power supply source should be clarified. (3) Types and required quality of equipment The situation of power use by equipment (for power, heating, lighting and electrical control, etc.) and the required level of accuracy (in terms of the allowable voltage fluctuation and frequency fluctuation) should be surveyed. (4) Equipment capacity, etc. The equipment capacity, power consumption level and electricity tariff (or estimated electricity tariff in the case of planning) should be surveyed.


- 3-11 -

(5) Period of use Any seasonal or daily fluctuation of power use and the range of fluctuation should be surveyed. (6) Year of installation and service life The year (date) of installation of each power demand equipment and its service life or planned period of use should be surveyed. (7) Likely problems associated with power cut The likely problems and financial losses associated with a power cut to power demand facilities should be surveyed.


- 3-12 -

3.9 Actual Field Survey Actual field survey for the design of structures for micro-hydropower system should be conducted after the identification of their location and route. The following should be done if necessary: (1) A proper understanding of the local topography is important for the planning of a

small-scale hydropower plant like the main exposed structure civil structures. Topographical surveying is particularly required for such structures as the intake facility, headtank and generating station, etc., each of which covers a wide area, to improve their design accuracy. In general, the accuracy of the topographical surveying around civil structures tends to be in the range of 1/100 – 1/200 for small to medium-scale hydropower plants. However, topographical surveying accuracy in the region of 1/500 should be sufficient for independent micro-hydro scheme because an error in topographical surveying hardly affects the work volume for small structures.

(2) During the implementation stage: For the waterway and access road, etc., route

surveying (center line and cross-section surveying) may be sufficient for planning and design purposes and should be effective from the viewpoint of cost reduction, particularly when the required surveying length is long. These routes must, however, be carefully determined based on the results of the field reconnaissance conducted by the planner(s).


- 3-13 -

[Ref. 3-1 Method of stream flow measurement]

1. Using electromagnetic current meter

Generally, the current meter used for the measurement of river flow is screw type. But nowadays, an

electromagnetic current meter that doesn’t have rotating parts is available in the market. This is suitable for

measurement of river flow in a small-scale hydro site. It is lightweight, and can be measured even in shallow

river.

In case of survey for small-scale hydropower development, a simple method like the following are sufficient

for discharge measurement using electromagnetic current meter.

(1) Three-points measuring method・・・・Vm = 0.25×( V0.2 + 2V0.6 + V0.8 )

(2) Two-points measuring method ・・・・Vm = 0.50×( V0.2 + V0.8 )

(3) One-point measuring method・・・・・Vm = V0.6

(4) Surface measuring method・・・・・・Vm = 0.8×Vs

where, Vm: Mean velocity Vs: Surface velocity

V0.2: Velocity at the depth of 20% below the water surface



Following should be considered when selecting the point of measurement in the stream .

(1) No irregular wave and whirlpools at the surface.

(2) No subsurface flow, back-flow, and stagnation.

(3) No irregular change of water level.

(4) No crossing-over of stream line.

During measurement, the riverbed should be cleaned, if necessary.


- 3-14 -

2. Float measuring method

Basically, float measuring method is applied during floods when measurement with current meter is not

possible. But, it is applicable during the stage where development sites are not decided yet or the current meter

is not available.

(1) Measuring method

1) Measurement should be made at the place where the axis of streambed is straight and the cross section

of the river is almost uniform.

2) Flowing distance of floats should be more than the width of river.

3)Setting transverse lines at the upstream and downstream perpendicular to the axis of streambed.

Flow-down distance (upstream and downstream lines) = L

4) Measuring the cross sectional areas at the upper and lower transverse lines to get the average value of

the cross sectional areas of flow (Amean).

Additional measurement should be made at the middle section of two lines if the cross

section of river is not uniform.

5) Floats are dropped at upstream of the upper transverse line, the time required from upper to lower

transverse line is measured.

6) Measurement should be done several times at different divisions of the river cross-section in the

transverse direction. (more than three divisions)

(2) Stream flow calculation formula

Vm = C×Vmean

C: (1) Concrete channel which cross section is uniform = 0.85

(2) Small stream where a riverbed is smooth = 0.65

(3) Shallow flow (about 0.5ｍ) = 0.45

(4) Shallow and riverbed is not flat = 0.25

(1) (2)

Vm = 0.85×Vmean Vm = 0.65×Vmean

(3) (4)

0.5 m

Vmean

Vmean Vmean

Vm = 0.45×Vmean Vm = 0.25×Vmean

Vmean


- 3-15 -

3. Weir measuring method

The discharge is small and the use of current meter or float measuring method is impossible, the weir as shown

below is built and discharge is measured by measuring the overflow depth at the river.

Upstream line

Downstream line

Flo

win

g di

stan

ce o

f fl

oats

(L

)

Drop line of floats

A – A’ Cross section

B – B’ Cross section

C – C’ Cross section

A – A’ C – C’ Mean Cross section


- 3-16 -

In this method, the stream flow can be obtained by following formula.

Q = C・L・h1.5

Q：Discharge (m3/s) C：Discharge coefficient L：Opening width of weir (m)

h：Overflow depth (m)

4. Others

It is applicable to use the following method to measure smaller stream flow.

C = 1.838 ( 1 + ) ( 1 - ) h 10

0.0012 ( h／L )1/2


- 3-17 -

Place of survey date time : water levelNo. RemarksDistance from left bankDepth of riverArea of flow section

Waterdepth Discharge





Average of Velocity (cm/s)dischage(l/s)

Survey sheet of discharge

1 2 3 4 5 6 7 8 9 10 11

50.0

40.0

30.0

20.0

10.0

Depth at point and velocity(cm, cm/s)

60.0

Cross-Section of river0.0


- 3-18 -

[Ref. 3-2 Method of head measurement]

1. Using clear hose method

The figure below shows this method. The method is useful for low head sites, since it is cheap and reasonably

accurate. To get the head of two points, measuring the difference of water level of the water-filled clear hose at

two points. Even a man who does not have a skill of survey work can apply this method.

H1

H3

H4

H5

H6

H2

Head

H1

H3

H4

H5

H6

H2

Head

Head = H1+H2+H3+H4+H5+H6

H1 = B1-A1

B1

H1

A1

Date :

No.Hi=Bi-Ai(meters)

1 0.85

2 0.86

3 0.86

4 0.91

5 0.99

6 0.75

7 0.30

8 0.90

9 0.70

10 0.74

11 2.30

12 0.66

10.82

Location :

0.70 1.36

Total Height (meters)=

1.00 1.74

0.20 2.50

1.00 1.90

1.00 1.70

1.00 1.75

1.00 1.30

1.00 1.91

1.00 1.99

1.00 1.86

1.00 1.86

Ai(meters)

Bi(meters)

1.00 1.85


- 3-19 -

2. Spirit level and plank method

Below figure shows the principle of this method. A horizontal sighting is established by a carpenter’s spirit

level placed on a reliably straight and inflexible plank of wood.

A method simpler than this is named Pole survey. The Pole survey method is a tape measure is used instead of

a wooden plank and a spirit level, a leveling rod is fixed perpendicularly, then a tape measure is moved up and

down along with a leveling rod. The reading value of a leveling rod of the position which reading value of a

tape measure decreases most is a height difference between points.

3. Using altimeter method

The principle of the altimeter is that it measures atmospheric pressure. This method is useful in case of long

survey distance or bad visibility. However, several measurements is required as shown in the following figure,

since in one measurement, accuracy is not expectable by changes during the day in temperature, atmospheric

pressure and humidity.


- 3-20 -

4. Using sighting meters etc. method

Hand-hold sighting meters measure angle of inclination of a slope (they are often called clinometers or Abney

levels). A head is calculated by the following formula using a vertical angle that is measured by a hand-hold

sighting meter, and a hypotenuse distance measured by a tape measure.

Ｈ＝Ｌ×sinθ H: Head L: Hypotenuse distance θ: Vertical angle


- 3-21 -

Place date Observing point Survey point Distance (m) Azimuth (°) Vertical interval Remarks

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Field-note of Topographic surveying


- 3-22 -


- 3-23 -


- 3-24 -


- 3-25 -


- 3-26 -

[Ref.3-4 Questionnaire for Households of Non-Electrified Villages] Household number

Name of Respondent

Sub unit of village

Barangay (village)

Circle the final result of the visit to this household 1. Completed 2. No household member at home or no competent respondent at home at time of visit 3. Postponed 4. Refused 5. Other (specify) Interviewer’s name Date Time interview began Time interview completed

Data input by Final Check by

1. FAMILY PROFILE 1. Number of family members (only living together in the same house)

Male adults at 20 yrs or over personsFemale adults at 20 yrs or over personsChildren less than 20 yrs old personsTotal persons

2. Number of school going children

University student personsHigh school student personsJunior high school student personsElementary school student personsTotal persons

3. How many of your family are earning income in the village in the village? persons 4. How many of your family members are living in other town to work? persons 5. Is your household headed by male or female?

Tick () Male Female

6. Which organization does any of your family belong

Barangay Cooperative PersonsBarangay Council PersonsOther (specify) Persons

7. How many of your family members graduated from (upper) high school? persons


- 3-27 -

2. Housing 8. How many rooms does your house have? rooms (including kitchen) 9. What is floor area of your house? m2 10. What type of roof is used for the house?

Type of roof Tick ()Tiled roof GI Sheet roof Thatched roof (straw, palm leaf)

3. Economic aspects

3-1. Household income

11. How much is your family earning from agriculture? Type of crops

Average amount of

production per cropping (kg)

Times of cropping per year

Average farm gate

price (Rp.)

Approximate annual earning (Rp.)

Average annual cost

(Rp.)

Subsistence/ cash crop

Rice Subsistence/cash crop

Subsistence/cash crop




12. Earnings from Fishery

Type of fish Annual average earning (Rp.)

Annual average cost (Rp.)

Subsistence/cash

Subsistence/cash

Subsistence/cash

Subsistence/cash

Subsistence/cash

13. What kind of income sources does your family have? Insert the amount of earning of the last month in

each category by each income earner.

Income earner Income source

1st income earner

2nd income earner

3rd income earner

4th income earner

5th income earner

Salaries/wages

Pension

Handicraft

Other cottage industry

Shops/restaurant

Services (e.g. hair-dress, car/bike garage)

Money transfer from outside the village

Others (Specify:)

Total

LIVING PLACE


- 3-28 -

3-2. Household Expenditure

14. How much did your household spend on each item for the last month?

Php/monthNo. Item of expenditure Amount Remarks 1 Food Incl. drinks. 2 Clothing Incl. personal goods as sandals/cosmetics. 3 Housing Housing loan repayment/house rent, etc. 4 Inputs for business Equipment & raw materials, if any. 5 Utilities Water, gas, electricity, fuel, & sanitation. 6 Tax If you pay income or property tax. 7 Education Incl. enrolment fee, books, uniforms, etc. 8 Transportation Incl. oils for your own cars/bikes. 9 Health care Medical treatment, medicines.

10 Others Other costs not specified in the above. Total

15. How much did your household spend on the utility except energy for the last month? Php./month

No. Item of expenditure Amount Remarks 1 Potable water For cooking, drinking & washing. 2 Irrigation water Agricultural use. 3 Sanitation Waste water & solid waste, toilet, etc. 4 Others Other costs not specified in the above.

Total

16. How much did your household spend on the energy-related item for the last month? Php./month

No. Item of expenditure Amount Remarks 1 Electricity Distributed electricity by lines 2 Gas Purchase cost. 3 Solar power Operation & maintenance cost for facilities

4 Kerosene Purchase cost. Do not include for car, bike, &

tractor, but include for lamps. 5 Diesel oil Purchase cost for diesel generator 6 Coal Purchase cost 7 Charcoal Purchase cost 8 Fuel wood Purchase cost 9 Dry batteries Purchase cost

10 Candles Purchase cost 11 Matches Purchase cost 12 Car battery charging Charging cost per time 13 Others Other costs not specified in the above.

Total

17. If your village is to be electrified and your house is to be connected with electricity distribution systems, all of your existing costs for lighting and heating as mentioned above may be saved. In this case, how much monthly charge are you willing to pay for new electricity services?

Range (Php./month

)

75 ～

100

100 ～

150

150 ～

200

200 ～

250

250 ～

300

300 ～

350

350 ～

400

400 ～

450

450 ～

500

More than 500

(specify:)

Tick () Php


- 3-29 -

4. Energy related property

18. Do you have following equipment for lighting and/or heating?

Kind of equipment

a) Generator b) Kerosene

lamp

c) Gas fired cooking

appliance

d) Car battery e) Others (Specify:)

Number ( )

19. What kind of electrical appliances does your household currently use? [ ] Bulb/fluorescent light units [ ] TV-set units [ ] Radio & cassette recorder set units [ ] Refrigerator units [ ] Air conditioner units [ ] Other, specify units 20. What kind of electrical appliances does your household currently use for productive activities? [ ] Sawmill machine [ ] Rice milling machine [ ] Rice dryer [ ] Irrigation pump [ ] Others, specify

5. Needs for electricity

5-1. Priority needs 21. Could you give your priority order on the followings needs?

Priority ExampleWater supply 1 Education 2 Health care 3 Sanitation (toilet, solid waste, drainage, etc.) 7 Electrification 4 Irrigation 6 Road improvement 5 Others (specify) 5-2. Effort to have access to electricity 22. Has your household ever attempted to have access to electricity? [ ] yes go to Question 23. [ ] no go to Question 30. 23. What type of electricity generation did your household plan to have access to? [ ] Diesel generator set [ ] Solar home system [ ] Wind power [ ] Micro hydropower [ ] Biomass [ ] Other, specify


- 3-30 -

24. Specify the reason for selecting the type of electricity generation. 25. Did your household succeed in having access to electricity? [ ] yes go to Question 26. [ ] no go to Question 27. 26. Is your generating system functioning as expected? [ ] yes go to Question 28. [ ] no go to Question 29. 27. If your household did not succeed in having access to electricity, explain the reason for the failure. 28. What positive impact could your household receive from electricity? Explain. 29. What problems did your household encounter regarding generating facility?

Problem Tick ()Expensive cost for fuel Unable to fix breakdown Insufficient electric power to meet the demand Other (specify)

5-3. Purpose of using electricity 30. If you can have access to electricity, what kind of electrical appliances and how many appliances do you

want to use? [ ] Bulb/fluorescent light units [ ] TV-set units [ ] Radio & cassette recorder set units [ ] Refrigerator units [ ] Air conditioner units [ ] Other, specify units 31. What facility/equipment do you want to use electricity for productive activities? [ ] Sawmill machine [ ] Rice milling machine [ ] Rice dryer [ ] Irrigation pump [ ] Others, specify

32. What public facilities do you think should have access to electricity? [ ] School [ ] Mosque/church [ ] Clinic/health center [ ] Water pump for drinking water [ ] Others, specify


- 3-31 -

5-4. Electrification by the organization other than Rural Electric Cooperative 33. Who/what organization do you think would be the most appropriate for the installation of the electricity

supply system? [ ] Provincial LGU [ ] Municipal LGU [ ] Barangay Association [ ] Barangay LGU [ ] NGO [ ] Private contractor [ ] Village members (including village head) [ ] Others, specify [ ] Don’t know 34. Do you and/or your family member volunteer to participate in working for the construction without any

cash reward if the generating facility is to be installed in the village? [ ] yes [ ] no 35. Who/what organization should be responsible for operation and maintenance of the system? [ ] Rural Electric Cooperative (REC) [ ] Provincial LGU [ ] Municipal LGU [ ] Barangay Association [ ] Barangay Council [ ] NGO [ ] Private contractor [ ] Barangay members (including barangay head) [ ] Others, specify [ ] Don’t know 36. Do you and/or your family member want to participate in working for operation and maintenance? [ ] yes [ ] no 37. Who/what organization should be responsible for billing and collection of charges for electricity? [ ] Rural Electric Cooperative [ ] Provincial LGU [ ] Municipal LGU [ ] Barangay Association [ ] Barangay Council [ ] NGO [ ] Private contractor [ ] Barangay members (including barangay head) [ ] Others, specify [ ] Don’t know 38. How should the electricity tariff be decided? [ ] Same level as REC’s tariff system [ ] Based on consultation with and consensus of the community [ ] Free of charge [ ] Other, specify


- 4-1 -

Chapter 4 PLANNING

4.1 Scheme of Development Layout

The tree types of waterway routes shown in Figure 4.1.1 below are examples of possible

layouts of micro-hydropower system. The ‘short penstock’ option, in most cases, is

considered the most economic scheme, but this is not necessarily the case.

Note: The channel could be shortened to avoid the risk and expense of construction across a steep slope.

Fig.4.1.1 Channel and penstock option:

Considering each option:

(1) Short Penstock

In this case, the penstock is short but the

channel is long. The long channel is exposed

to the greater risk of blockage, or of collapse

or deterioration as a result of poor

maintenance. Installing the channel across a

steep slope may be difficult and expensive.

The risk that the steep slope may erode

makes the short penstock layout an

unacceptable option, because the projected

operation and maintenance cost of the

scheme could be very expensive, and it may

outweigh the benefit of initial purchase cost.


- 4-2 -

(2) Long Penstock

In this case, the penstock follows the river.

If this layout is necessary, because the

terrain would not allow the construction of

a channel, certain precautions must be

taken. The most important consideration is

to ensure that seasonal flooding of the river

will not damage or deteriorate the penstock.

It is also important to calculate the most

economic diameter of penstock; in the case

of a long penstock, the cost will be

particularly high.

(3) Mid-length Penstock

The mid-length penstock may cost more

than the short penstock, but the cost of

constructing a channel that can safely cross

the steep slope may also be avoided. Even

if the initial purchase and construction

costs are greater in this case, this option

may be preferable in case there are signs of

instability in the steep slope.


- 4-3 -

4.2 Data and Reference to Consider for Planning

4.2.1 Hydrograph and Flow Duration Curve

Hydrograph shows how flow varies throughout the year and how many months in a

year that a certain flow is exceeded.

Fig 4.2.1 An example of Hydrograph

This same information is also presented in a ‘Flow Duration Curve’ for the stream. The

hydrograph is converted to flow duration curve simply by taking all the flow records

over many years and placing them with the highest figures on the left and the lower

figure placed progressively over to the right.

Fig.4.2.2 An example of Flow Duration Curve

Daily Discharge Jun 2006-May 2008 (C.A=20.2km2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

J J A S O N D J F M A M J J A S O N D J F M A M

Dis

char

ge (

m3 /s

)

Duration Curve at Intake Site (C.A.=20.2km2)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Percentage (%)

Dis

char

ge (m

3/s

)

Duration Curve


- 4-4 -

The flow duration curve is useful because the power that could be generated can be

superimposed onto it so that it is possible to calculate the time in a year that certain

power levels can be obtained. This is also a planning tool to determine the size of

turbine to be installed indicating the required variable flow performance of turbine and

the plant factor constraints which will result from any particular choice of turbine size.

4.2.2 Plant Factor and Load Factor

(1) Plant Factor

‘Plant Factor’ is very important term for hydropower planning. Plant factor is defined in

the next equation.

Geannual

Plant Factor = %

Pmax × 365 × 24

and

Qave’ Area of A-b-c-C-D in Fig.4.2.3

Plant Factor of Flow = or %

Qd Area A-B-C-D in Fig.4.2.3

Where;

Geannual : the possible annual electric generation (kWh)

Pmax : maximum output (kW)

Qave’ : average discharge which is less than Qd (m3/s・day)

Qd : design discharge (m3/s)

For a run-of-river type of hydropower scheme, optimum plant factor can be generally

taken from the following range:.

For micro-hydro : 80 ～ 100 ％ (For Rural Electrification)

Mini-hydro : 70 ～ 90 ％（In the Philippines）


- 4-5 -

(2) Load Factor

The term ‘Load Factor’, often mistaken to be the same as the plant factor, is defined in

the equation below.

Annual electric generation usable by demand facility

Load Factor = (%)

Annual possible electric generation

A key-planning rule for micro-hydro scheme is therefore “Plan for the highest possible

load factor”.

Fig4.2.3 Qave’ and Qd for Plant Factor of Flow

0 100 200 300 365

Riv

er F

low

(m

3 /s)

Days

A B

C

b

c

Qd

D


- 4-6 -

4.3 Selection of Locations for Main Civil Structures

4.3.1 Location of Intake

The location of the intake is selected considering the conditions described below.

Extreme care must be taken in this selection for the development of small-scale

hydropower as the cost of the intake facilities significantly determines the development

project economy.

(1) River Channel Alignment

For small-scale and run-of-river types of hydropower plant, the appropriate section

within the river channel to construct the intake structure is where the channel is as

straight as possible in order to ensure steady and smooth flow of water to the intake and

also to prevent scouring of the river banks downstream of the intake site.

(2) Stability of Hillside Slope

The presence of a landslide or unsteady slope near an intake weir site causes concerns

for possible obstruction at the water intake by sediments from the landslide or erosion.

Sufficient consideration should, therefore, be given to the stability of nearby hillsides as

part of the intake location selection process.

(3) Use of existing civil structures

In small-scale hydropower development, the use of existing civil structures such as

barangay roads, intake facilities for agriculture and irrigation channels, etc. can

contribute to the reduction of the development cost. Careful consideration should,

therefore, be given to the selection of the intake location so that such civil structures

already in place can be used.

(4) Use of natural topographical features

The use of naturally formed pool for water intake will not only help in the cost

reduction but also conserving the waterfront environment, including the riverside

landscape and riparian ecosystem.

When the use of natural topographical features is planned, proper analysis of the


- 4-7 -

following concerns should be considered:

Preservation of the natural pool

Removal method of sedimentation

(5) Intake Volume and Flood Water Level

In general, an intake weir is located at a narrow section of a river to reduce the

construction cost of the main body of the intake weir. However, it must be noted that the

selection of such a narrow section is not necessarily advantageous for a small-scale

hydropower plant because of the following reasons.

In the case of the Tyrolean-type intake method, the length in the cross-sectional

direction must match the anticipated design discharge. (0.1m3/s of inflow water per

1m of intake length)

When a weir is constructed at a narrow section, the flood water level at the site

inevitably becomes higher, necessitating an increased cross-sectional area of the weir

as well as an increased bank protection height and length to ensure the stability of the

weir.

(6) Site Conditions for Settling Basin and Headrace, etc.

Select the preferable site for the settling basin, headrace and other structures taking into

consideration the conditions for the weir. It is also important to carefully consider the

topographical and geological conditions of the settling basin site and headrace route.

(7) Existence of River Water Use in Reduced Discharge Section

Water intake for agricultural or other purposes should be considered in the survey in

order that the use of river water for power generation will not affect the present use of

the river water.

8) Existing Features in Backwater Section

Existing features, such as roads and farmland, etc., in lower areas should also be

considered in the selection of the location of the intake weir to avoid flooding.

If the location of the intake weir is in a location which affects existing features, the


- 4-8 -

geographical area to be affected by backwater due to the construction of the intake weir

should be clarified by appropriate calculation. It will also be necessary to construct river

bank protections and drainage structures to protect the existing facilities.

4.3.2 Headrace Route

(1) Topography

A careful survey of the topography of the headrace route of a micro-hydropower system

is necessary since the headrace is usually an exposed structure such as an open or

covered channel. When an open channel is to be constructed on a hillside, proper

investigation as to the gradient or slope of the headrace route must be done. If a valley

or a ridge exists along the headrace route, the actual route should be selected after

examining the best route (siphon for a valley section; open excavation or culvert for an

elevated ridge section).

(2) Ground Stability

The ground stability of the headrace route must be carefully examined to avoid

incidents of loss of the waterway due to slope collapse in the case of the ground-type

(exposed) headrace.

(2) Use of Existing Structures

It is advantageous to locate the headrace route along an existing road or irrigation

channel to reduce the cost, improve the workability and make it relatively easy to

evaluate the slope stability. However, the following concerns must be taken into

consideration for the use of existing structures:

Maintenance of existing canal, road, drainage, etc.

Ensure water quantity for irrigation and efficient water diversion method

4.3.3 Location of Head Tank

(1) Topographical and geological conditions

The headtank is often located at a ridge section and on a highly stable ground consisting

of hard rock, etc. The possibility of minimal excavation work, including that for the

penstock, offers favorable condition for selection of the site for headtank.


- 4-9 -

However, it must be noted that the location of the headtank at a ridge section is not

appropriate under the following conditions:

The level of consolidation is generally low at the ridge section which is located in a

shallow area developed from advanced erosive dissection of the valley.

There will be larger fluctuations in the water level inside the tank which will cause

possible obstruction to the smooth flow of operation due to the large volume of water

required as the load changes. In such a case, it is advisable to design a headtank with

a bigger diameter that covers an area wide enough to absorb load fluctuations. In this

case, the desired location for the headtank should be on a relatively flat area rather

than on a ridge section.

(2) Ease of Dealing with Effluents

A spillway for a small-scale hydropower system may be omitted, however, if a spillway

for the headtank is introduced, the method of dealing with effluents must be carefully

examined. (There have been reports of the ground being washed away because of the

absence of a spillway for the excess water from the headtank.)

The installation of a spillway parallel to the penstock route should not cause any major

problems, however, the direct discharge of surplus water and sediment inside the

headtank to a nearby stream or hillside slope requires careful examination of the

discharge point. The profile as well as cross-sectional alignment of the spillway are

carefully designed to prevent scouring of the nearby ground due to expected volume of

water spillage.

The combined function of a settling basin and headtank will significantly help in

reducing of overall investment cost of micro-hydropower development. Therefore, the

possibility of introducing a combined headtank and settling basin should be carefully

examined at the planning stage.

4.3.4 Penstock Route

The penstock route should be selected considering the following parameters:

(1) Hydraulic gradient


- 4-10 -

(2) Topography of the penstock route

(3) Ground stability of the penstock route

(4) Use of existing infrastructures like roads, irrigation canals and others

The parameters to note for the selection of the penstock route are basically the same as

those for the selection of the headrace route but its relationship with the hydraulic

gradient must be carefully analyzed.

The penstock route must be designed to ensure safety vis-à-vis specific internal as well

as external pressures and that the profile of the penstock route must be below the

minimum hydraulic gradient line, i.e. minimum pressure line.

This minimum pressure line is determined by taking the internal pressure fluctuation in

the penstock at the time of rapid load shut-down into consideration. The range of

pressure fluctuation is larger in the downstream because it is influenced by changes of

the discharge at the turbine over time. Therefore, careful attention is necessary at a site

where the length of the penstock route is long compared to the head as shown in the Fig.

4.3.1.

Careful examination is also required in setting the location of the Francis turbine with a

slower specific speed as the range of pressure fluctuation can be widened due to the

abrupt control vane operation because of the increasing revolution (speed) even at

longer closure time of the control vane.

For other turbines, closing speed of the control vane is almost in proportion to the speed

of discharge reduction, however, no special problem occurs provided that an adequate

closure time is set.


- 4-11 -

Fig. 4.3.1 Example of site where penstock route is long compared to head

Fig. 4.3.2 Change of discharge at rapid load shut-off for Francis turbine with

slower specific speed

Powerhouse

Penstock

Minimum Pressure

Negative pressure will occurin this area

Head Tank Maximum Pressure Line

Change of flow due to operation by the control vane

(longer closure time)

Time 0

Qmax

Change of flow due to change of the revolution

(Shorter closure time)

Dis

char

ge


- 4-12 -

4.3.5 Location of powerhouse

Careful attention must be made to the following conditions in the selection of the

powerhouse location:

(1) Accessibility

It is desirable for the powerhouse to be located at a site with easy access for operation

and maintenance purposes.

(2) Conditions of the Foundation

The foundations of the powerhouse must be strong enough to withstand the installation

of heavy loads like the electro-mechanical equipment. For a micro-hydropower plant, a

compacted gravel layer may be sufficient because of the relatively lightweight

equipment (approximately 2 – 3 tons/m2).

(3) Flood Water Level

The location of the powerhouse must avoid the level and section where the water flows

to avoid scouring and to prevent inundation of the powerhouse during high flows.

A small-scale hydropower station is planned for a small river in a mountainous area

where the flood stage is not recorded or established. In this case, the flood water level

could be assumed based on the information listed below that could be used in the

determination of the ground elevation of the powerhouse with sufficient margin:

Information obtained from local residents

Ground elevation of nearby structures (roads, embankments and bridges, etc.)

Traces of flooding and vegetation boundary

(4) Installation Conditions for Auxiliary Facilities

Space for the installation of an outdoor substation is required near the powerhouse and

the site must be selected in consideration to the possible extension and the direction of

the transmission line.

However, when the transmission voltage is the same as the generating voltage, the size

of the required space is small. Accordingly, the space created by the construction of the


- 4-13 -

foundations for the powerhouse is often sufficient to accommodate such auxiliary

facilities.

4.3.6 Location of Tailrace

The location of the tailrace is determined using the same conditions as the powerhouse

location because it is located adjacent to the powerhouse. In other cases, the location of

the tailrace is decided by taking the following items into consideration.

(1) Flood Water Level

The tailrace channel should be preferably placed above the expected flood water level.

When the base elevation of the tailrace is planned to be lower than the flood level, the

location and base elevation of the tailrace must be decided in consideration of (i)

suitable measures to deal with the inundation or seepage of water into the powerhouse

due to flooding and (ii) a method to remove sediment which may occur in the tailrace

canal.

(2) Existence of Riverbed Fluctuation at Tailrace

When riverbed fluctuation is expected to take place in the future, the location of the

water outlet must be selected so as to avoid any trouble to its operation due to

sedimentation in front of the tailrace.

(3) Possibility of Scouring

Careful attention must be made to avoid the scouring of the riverbed and nearby ground.

The selection of a location where protective measures can be easily applied is essential.

(4) Flow Direction of River Water

The tailrace must be directed (in principle, facing downstream) so as not to disrupt the

smooth flow of the river water or a location which allows the direction of the tailrace as

that of the river flow should be selected.


- 4-14 -

4.4 Supply and Demand Plan

4.4.1 Selection of Power Demand Facilities

The following items must be considered in the installed capacity:

(1) Power Uses

Each power demand facility shows specific load characteristics depending on various

power uses, the selection of the power demand facilities to be served should take the

specifications of the generating unit and the load characteristics of each facility into

consideration.

The load characteristics corresponding to specific power uses are outlined below:

a) Use for Lighting

The load for lighting is constant while it is in use and less fluctuations than other

power uses. In general, power use for lighting is concentrated at night and the

time of use fluctuates depending on the weather and length of sunshine duration.

b) Use for Heating and Drying

The main power uses are heating, keeping warm and drying using electric heaters.

However, the continuous use of power for heating is rare. In most cases, power is

intermittently used in response to a set temperature.

In an area with distinctive dry and wet seasons where agricultural products are

currently dried by solar heat, the use of electric dryers, etc. enable power

consumption in line with seasonal fluctuations of the generated power output.

This constitutes a very effective means of improving the efficient use of electrical

power.

c) Use for Motive Power

The use of power to operate a motor shows the following load characteristics:

At start-up, current is several times higher than the rated current flows (the

duration is generally not more than 10 seconds).

The load fluctuates in relation to the motive power required by a machine. The

load is basically constant in the case of an electric fan or pump, etc. but

considerably fluctuates in the case of sawing operation, etc.


- 4-15 -

An automatically controlled motor for air-conditioning as well as heating

frequently, in repetitive manner, starts and stops.

In the case of a power plant in an isolated operation, the start up of its motor may

temporarily cause a state of excessive load that may result to the stoppage of

generating operation.

(2) Transmission and Distribution Costs

The construction of a small-scale hydropower station near the power demand facilities

is desirable in order to increase its efficiency. Accordingly, it is necessary to select the

power demand facilities when planning the demand by taking into consideration both

the benefits and the transmission and distribution costs of power supply.

(3) Contribution to Local Development

The main purpose of the small-scale hydropower development discussed here is the

vitalization of the local economy. It is desirable to give priority to the types of power

demand facilities listed below because of their perceived strong to local development:

a) Those capable of using local resources.

b) Those capable of appealing to the environment near or outside the area.

c) Those capable of assisting the creation of employment opportunities.

d) Those capable of contributing to the promotion of close cooperation among

residents.

4.4.2 Scheme of Development based on Supply and Demand

It is necessary that the output of a small-scale hydropower plant that has no back-up

power generation source to be higher than the demand. In the case of a run-of-river type

micro-hydropower plant, the optimal scale is that which corresponds to the maximum

demand capacity within the range of “the developable maximum output”1 which is

basically determined based on “the minimum usable discharge for generation”2. The

procedure for this examination is described next.

1 Maximum output which can be developed. 2 Drought discharge among the various river discharges which can be used for power generation.


- 4-16 -

(1) Decision on Minimum Usable Discharge (Qumin) for Generation

The minimum usable discharge for generation (Qumin) is decided in consideration of the

following items:

a) Establishment of usable river discharge for generation (Qu)

The Qumin is determined based on the discharge which is calculated by subtracting

the maintain discharge in the reduced discharge section from the river discharge

at the intake point (usable discharge for generation: Qu).

b) Frequency of permissible break power generation

The Qumin is also determined by the frequency of permissible break power

generation (see Fig. 4.4.1 and Fig.4.4.2).

The frequency of permissible break power generation is in turn decided by the

type and importance of the power demand facilities/equipment, user intentions

and other factors. In general, the drought discharge under the flow duration for Qu

calculated by the method described above or some 90 – 95% discharge rate3

forms the base. However, as the flow duration changes every year, a standard

flow duration year must be selected through sufficient discussions with users for

the planning of the base discharge.

(2) Decision on Maximum Output (Pumax)

The maximum output (Pumax) that could be develop is decided in the following manner

depending on whether or not seasonal demand fluctuations exist.

a) Case of constant demand throughout the year

When a plant is assumed to be a run-of-river type, the Pumax is the power

generation potential under the Qumin described earlier.

3 Discharge rate (percentage) when 365 days constitute 100% in the flow duration diagramme.


- 4-17 -

Fig.4.4.1 Maximum scale of possible development for case where constant

demand throughout the year is assumed

b) Case of seasonal demand fluctuation

When the demand in the wet season is expected to exceed the demand in the dry

season, generating operation is principally based on the maximum load in the wet

season or the light load in the dry season. When the discharge in the dry season

drops below “the minimum discharge for generation (Qmin)4 ”, generating

operation is no longer possible. Therefore, the Qumin must be set above the Qmin.

In this case, the Pumax can be calculated by the following formula:

4 Qmin means the minimum discharge determined by the efficiency characteristics of the turbine and

power generation is impossible below this level.

Permissible break powergeneration

Qumin

m3/skW

：Power generation potential ：Max output of possible development

1 2 3 4 5 6 7 8 9 10 11 12

Permissible break power generation

Pumax

Qumax Qumin

Qmin/Qmax

Pumax= Power generation potential at Qumin

Efficiency rate at Qmin (min/max)


- 4-18 -

Fig. 4.4.2 Maximum scale of possible development for case of seasonal demand

fluctuation

Table 4.4.1 Minimum discharge for generation (Qmin) for various types of turbines

Type of Turbine Flow / Max. Flow

(Qmin / Qmax)

Turbine Efficiency /

Max. Turbine Efficiency

(min / max)

Conditions

Horizontal Shaft

Francis

30％ 0.70 Light burdened runner

Horizontal Shaft Pelton 15％ 0.75 2 nozzles

Horizontal Shaft Pelton 30％ 0.90 1 nozzle

Crossflow 15％ 0.75 Twin control vanes

Crossflow 40％ 0.75 Single control vane

Turgo Impulse 10％ 0.75 2 nozzles

Turgo Impulse 20％ 0.75 1 nozzle

Reverse Pumps Generating operation is difficult other than at the rated discharge

(3) Decision on Scale of Development and Power Demand Facility

a) Case where change of demand plan is difficult

When it is difficult to change the power demand facility and its capacity assumed

in the demand plan, the assumed maximum demand capacity within the range of

the Pumax becomes the optimal scale of development.

Qumin

≧

m3/s kW

1 2 3 4 5 6 7 8 9 10 11 12

Qmax

：Power generation potential

：Max output of possible development

Permissible break power generation

Pumax


- 4-19 -

Fig. 4.4.3 Optical scale of development for case where constant demand

throughout the year is assumed

Figure 4.4.4 Optimal scale of development for case of seasonal demand

fluctuation

Qumin

m3/skW

1 2 3 4 5 6 7 8 9 10 11 12

Optimum development

scale

：Power generation potential ：Max. output of possible development

：Max. demand capacity

Qumin

≧Qmin

m3/skW

1 2 3 4 5 6 7 8 9 10 11 12

Qmax

：Power generation potential ：Max. output of possible development

： Estimated power

Optimum development

scale


- 4-20 -

b) Case where change of demand plan is possible

When a change of the demand plan to some extent is possible, the demand

capacity is changed within the range of the Pumax to select the most effective case.

The following criteria can be used to judge the best case. Their general priority

can be difficult to decided, however, because it depends on each development

site.

Economy

Social advantages (creation of new employment, promotion of tourism / industry

and others)

Intentions of developer

Others

When economy of the project is given priority, the demand plan must be

formulated to maximize the effective utilization rate of the power generation

potential. This is in view of the fact that generated electric energy in excess of the

demand capacity by an independent system such as a small-scale hydropower

plant cannot be expected to have any benefit.

Annual electric generation usable by demand facility

Load Factor = (%)

Annual possible electric generation

The concrete processes to determine the optimal scale of development are

described below:

a. Setting up of demand

Several cases of demand plan are formulated based on the demand projection

from survey results but within the range of the distribution. At this time, the

priority of each demand facility must be carefully analyzed, taking the

following items into consideration:

Importance of facility (equipment)

Profit from each demand facility


- 4-21 -

Fig.4.4.5 Example of demand plan

b. Calculation of effective use of electric energy

The annual effective use of electric energy is calculated by comparing the

power generation potential not higher than Pumax with the demand set in “a.”

above for each season.

Fig.4.4.6 Example of annual supply and demand balance

c. Decision on optimal scale of development

By calculating the unit construction cost or the cost-benefit ratio per kWh for

kW

1 2 3 4 5 6 7 8 9 10 11 12

：Demand ‘Case 1’



kW

1 2 3 4 5 6 7 8 9 10 11 12

Efficient use of energy

In case of demand ‘Case


：Power Generation Potential

：Max. Scale of Possible Development


- 4-22 -

the effective use of electric energy, the optimal scale of development is

established to minimize such unit cost or cost-benefit ratio.

Formula 3-1a: Case of Unit Construction Cost

Formula 3-1b: Case of Cost-Benefit Ratio

Annual cost (C) = annual cost of the plant in question

= construction cost×annual expense ratio (use of the

standard calculation method for an ordinary case)

Benefit (V) = (electricity charge for each power demand facility)

= (demand capacity (kW)×basic charge×months＋

effective electric energy (kWh)×metered charge)

C/V = annual cost (C) / benefit (V)

4.4.3 Daily Supply and Demand Plan

Electricity is basically used for lighting and operation of household appliances such as

television and radio. Because of lesser demand in daytime, electricity is more than

enough so the excess electricity is only used by a dummy load. So it is necessary to

plan the use of the excess power for livelihood or local industry such as rice mill, coffee

mill and ice plant in the daytime. That image is shown as follows Fig. 4.4.7.

Unit construction cost per kWh =Construction cost

Annual effective electric energy


- 4-23 -

Fig.4.4.7 Effective use in the daytime electricity

forHouseholds

LampT.V

Radioetc.

forHouseholds

LampT.V

Radioetc.

Night Time Night TimeDay Time

Outp

ut

and

Dem

and

(kW

)

No Demands

Time

Dai

ly O

utu

t (k

W)

forHouseholds

LampT.V

Radioetc.

forHouseholds

LampT.V

Radioetc.

Night Time Night TimeDay Time

Outp

ut

and

Dem

and

(kW

)

No Demands

Time

Local Industry

Rice millCoffee millIce plant

etc.

Dai

ly O

utu

t (k

W)

Manual for Micro Hydro Power Development Chapter 5

-5- 1 -

Chapter 5 DESIGN FOR CIVIL STRUCTURES

The main obstacle for a small-scale hydropower plant is the high development cost. In

this chapter, element technologies are described assuming the need to reduce the

construction cost of civil structures (no description is given for those which equally

apply to the design of an ordinary hydropower plant).

5.1 Basic Equation for Civil Design

The discharge is one of the important aspects to consider in the design. It is directly proportional to

the cross sectional area and velocity of the water.

5.2 Intake Weir (Dam)

5.2.1 Types of Intake Weir

There are a number of basic types of dam or intake weirs as listed below:

(1) Concrete gravity dam

(2) Floating concrete dam

(3) Earth dam

(4) Rockfill dam

(5) Wet masonry dam

(6) Gabion dam

(7) Concrete reinforced gabion dam

(8) Brushwood dam

(9) Wooden dam Wet masonry dam

Q = A x V

Q: Discharge (m3/s)

A: Cross sectional area of water (m2)

V: Velocity of water (m/s)

V = Q / A

A = Q / V AV

1 secondV

A

1 second

○ meters/

○ meters/


-5- 2 -

(10) Wooden frame with gravel dam

The rockfill and gabion dams and the like are popularly used in Southeast Asian

countries because of several advantages such as (i) little influence by the conditions of

the ground base and (ii) relatively easy to repair when damaged. However, they could

be damaged by flooding due to their structure and their application should be carefully

examined on the importance of constructing such a civil structure and the conditions of

the downstream.


-5- 3 -

Table 5.2.1 Basic types of intake weirs for small-scale hydropower plant and application

conditions

Type Outline Drawing Application Conditions Concrete gravity dam

Concrete is used for the construction of the entire body.

Foundations: in principle, bedrock River conditions: not affected by the

gradient, discharge or level of sediment load

Intake conditions: good interception performance and intake efficiency

Floating concrete dam

Lengthened infiltration path of the foundations by means of cut-off, etc. to improve the interception performance

Foundations: in principle, gravel River conditions: not affected by the



Earth dam Earth is used as the main material for the body; the introduction of a riprap and core wall may be necessary depending on the situation.

Foundations: variable from earth to bedrock River conditions: gentle flow and

easy to deal with flooding

Intake conditions: good intake efficiency because a high interception performance is possible with careful work


-5- 4 -

Type Outline Drawing Application Conditions

Rockfill dam Gravel is used as the main material for the body. The introduction of a core wall may be necessary depending on the situation.

Foundations: various, from earth to bedrock River conditions: river where an

earth dam could be washed away by the normal discharge

Intake conditions: limited to the partial use of river water due to the low intake efficiency

Wet masonry dam

Filling of the spaces between gravel with mortar, etc.

Foundations: In principal Gravel River conditions: not affected by the



Gabion dam Gravel is wrapped by a metal net to improve the integrity.

Foundations: various, from earth to bedrock River conditions: river where a

rockfill dam could be washed away by the normal discharge


Concrete reinforced gabion dam

Reinforcement of the gabion surface with concrete

Foundations: : In principal Gravel River conditions: river where the

metal net could be damaged due to strong flow

Intake conditions: applicable when a high intake efficiency is required


-5- 5 -

Type Outline Drawing Application Conditions

Brushwood dam

Simple weir using locally produced tree branches, etc.

Foundations: various, from earth to gravel layer River conditions: loss due to flooding is assumed Intake conditions: at a site with a low

intake volume or intake from a stream to supplement the droughty water flow

Wooden dam Weir using wood

Foundations: various, from earth to bedrock River conditions: relatively gentle

flow with a low level of sediment transport

Intake conditions: a certain level of intake efficiency is secured with a surface coating, etc.

Wooden frame with gravel dam

The inside of the wooden frame is filled with gravel to increase the stability.

Foundations: various, from earth to bedrock River conditions: river at which a

rockfill dam could be washed away by the normal discharge


5.2.2 Weir Height Calculation

The weir volume is proportionate to the square of the height, it is important to decide

the weir height taking the following conditions into consideration.

(1) Conditions restricting waterway elevation


-5- 6 -

To decide for the weir height, it is necessary to take the topographical and geological

conditions of the waterway route into consideration in addition to the conditions at the

weir construction site. Careful examination is necessary at the site where the

construction cost accounts for a large portion of the total construction cost.

In case the waterway is to be constructed along an existing road, the weir height is

often planned with reference to the elevation of the road.

(2) Possibility of riverbed rise in downstream

Since the weir height for a small-scale hydropower plant is generally low, there is

possibility that its normal function could be disrupted by a rise of the riverbed in the

downstream.

Accordingly, the future riverbed rise should be considered in the selection of the weir

height if the planned site falls under any of the following cases:

1) Gently sloping river with a high level of transported sediment

2) Existence of not fully filled check dam, etc. in the downstream of the planned

intake weir

3) Presence of erosion in the downstream with possibility of continuous erosion in

the future

4) Existence of a narrow section in the downstream which obstructs the flow of

sediment and/or driftwood

(3) Conditions to remove sediment from upstream of the weir and settling basin by

intake method (Tyrolean intake and side intake)

Under normal circumstances, the weir height should be planned to exceed the calculated

value by the following method to ensure the smooth removal of sediment from the

upstream of the weir and the settling basin.

1) Side intake

In the case of side intake, following Case (a) or Case (b), whichever is higher, is

adopted.


-5- 7 -

Case (a). Weir height (D1) determined in relation to the bed elevation of the scour

gate of the intake weir

D1 = d1 + hi

Case (b). Weir height (D2) determined by the bed gradient of the settling basin

D2 = d2 + hi+ L (ic – ir)

Where,

d1 : height from the bed of the scour gate to the bed of the inlet (usually 0.5 –

1.0 m)

d2 : difference between the bed of the scour gate of the settling basin and the

riverbed at the same location (usually around 0.5 m)

hi : water depth of the inlet (usually determined to make the inflow velocity

approximately 0.5 – 1.0 m/s)

L : length of the settling basin (see Chapter 5-5.3 and Fig.5.3.1)

ic : inclination of the settling basin bed (usually around 1/20 – 1/30)

ir : present inclination of the river

Fig.5.2.1 Sectional view of side intake and weir

Therefore, the height of the weir depends on the river slope. In general, D1 will be adopted in the

steep slope river, on the other hand D2 will be selected in the gentle slope river.

Flush gate

ic

ir

Intake

L

hi

d1

d2


-5- 8 -

2) Tyrolean intake

A Tyrolean intake where water is taken from the bottom assumes that the front of

the weir is filled with sediment and, therefore, the weir height is determined by

Case D2 for side intake.

D2 = d2 + hi + L (ic – ir)

Fig.5.2.2 Sectional view of Tyrolean intake and weir

() Influence on electric energy generated

At a site where the usable head is small or where it is planned to secure the necessary

head by a weir, the weir height significantly influences the level of generated electric

energy. Accordingly, it is necessary to determine the weir height at a site by comparing

the expected changes of both the construction cost and the generated electric energy

because of different weir heights.

(5) Influence of back water

When roads, residential land, farmland and bridges, etc. exist in a lower elevation area

in the upstream of a planned intake weir site, it is necessary to determine the weir height

to prevent flooding due to back water. Particularly at a site with a high weir height, the

degree of influence on the above features must be checked by means of back water

calculation or other methods.

Inlet L

ic

ir d2

D2 hi


-5- 9 -

5.3 Intake

5.3.1 Types of Intake

(1) Side-Intake

Below is an example of a “Side-Intake Type”. The side-intake type must be with a

flushing gate (stop logs use for micro/mini-hydropower).

Image and dimension of “Side-Intake”

(2) Dimension of Intake (“Side-Intake)

In the design of intake dimension, the following matters should be considered.

The dimension of the intake should be designed that the velocity of inflow at

the intake is 0.5-1.0 m/s. If the velocity is too slow, the dimension of intake

become big. In this cake, excess inflow also becomes big (Refer to 5.2.2)

On the other hand, if the velocity is too fast, the inflow became unstable and

the head loss is relatively big.

The ceiling of the intake should be designed with allowance of 10-20cm

from the water surface. The allowance should be obtained for stable inflow.

The height and the area of intake should be designed with the minimum size.

b

hi

dh

Vi

hidh=hi+0.15m

0.150 m

b

Intake Weir

Flushing gate/ Stop-log

Intake


-5- 10 -

(3) Tyrolean Intake

There are several types of simple intake designs, which aims at reducing the weir height

and omitting the flushing gate (hereinafter referred to as the Tyrolean intake design) for

a hydropower plant. Two typical examples are listed below.

Bar screen type

Bar-less type

The details of these two types are shown in Table 5.3.1.


Table 5.3.1 Typical examples of Tyrolean intake methods

Intake Method Outline Drawing Characteristics Advantages and Problems Found by Actual Performance Survey

Bar screen type

If a screen is installed to cover most of the river channel, it is highly resistant to riverbed fluctuations. A sufficiently wide intake width enables 100% intake of river water. As overflow may occur due to fallen leaves, etc. gathering on the screen surface, the screen width should have a sufficient margin. The sedimentation capacity of the weir to deal with sediment inflow should also be analysed.

This type is popularly used and the intake rate is said to be generally 0.1 – 0.3 m3/s per unit width based on a bar installation angle of up to 30, an inter-bar space of 20 – 30 mm and a bar length of approximately 1 m.

< Advantages > A scour gate of intake weir can be omitted. A compact intake facility is suitable for a

narrow or rapid river. Stable intake is possible despite a change of the

riverbed upstream. < Problems > At the time of flooding or water discharge,

sediment and litter flow into the waterway. A screen which is clogged with gravel, etc.

requires much labour for its removal.

Bar-less type The running water usually overflows the fixed weir top and is guided into the settling basin via an intake channel placed across the river channel and along the endsill (deflector). With an increase of the river discharge, the running water overflows the endsill and eventually becomes a rapid flow to fly over the endsill, making intake impossible at the time of flooding. However, sediment deposited in the intake channel is washed away towards the downstream of the endsill, making maintenance of the intake channel easier. While the sectional form of this type is similar to that of the bar screen type, the absence of a screen means a reduction of the maintenance cost and labour related to the screen.

< Advantage) A compact intake facility is suitable for a

narrow or rapid river. Stable intake is possible despite a change of the

riverbed upstream. Sediment and litter are discharged naturally at

the time of flooding. < Problem > Plenty of sediment and litter inflow to the

waterway. Frequently of scouring of settling basin is

required.

-5- 11-


-5- 12-

5.3.2 Important Points for Intake Design (for Side-Intake)

For the design of the intake for a small-scale hydropower plant, it is necessary to

examine the possible omission of an intake gate in order to achieve cost reduction.

In the case of a small-scale hydropower plant, the headrace is usually an open channel, a

covered channel or a closed conduit. When this type of headrace is employed, it is

essential to avoid inflow of excess water , which considerably exceeds the design

discharge, as it will directly lead to the destruction of the headrace.

Meanwhile, the use of an automatic control gate for a small-scale hydropower plant

results an increase in construction cost, a manual control is an option. In the case of the

intake facility for a small-scale hydropower plant being constructed in a remote

mountain area, a swift response to flooding is difficult. The following method is,

therefore, proposed to control the inflow at the time of flooding without the use of a

gate.

(1) Principle

This method intends the design of an intake which becomes an orifice with a rise of the

river water level due to flooding.

The inflow volume in this case is calculated by the formula below.

Flood Water Level

→

Water Level of Spillway

Normal Water Level

Ｂsp

ｈｓp

Ai

hi

dh

dh

hi

bi

H


-5- 13-

Q f= Ai ×Cv × Ca × (2 ×g × H ) 0.5

Where,

Qf : inflow volume of submerged orifice (m3/s)

Ai : area of intake (m2) Ai=bi × (dh + hi) dh=0.10～0.15m

hi : water depth at the intake opening (m)

bi : width of the intake opening (m)

dh : clearance at the intake

Cv : coefficient of velocity: Cv = 1/(1 + f)

f : coefficient of inflow loss (see Fig.5.2.1)

Fig.5.2.1 Coefficient of inflow loss of various inlet form

Bsp, hsp: refer to Chapter 5-5.3 Settling basin

Ca : coefficient of contraction (approximately 0.6)

H: water level difference between upstream and downstream of the orifice during

flood (m)

(2) Equipment outline

The important points for design are listed below:

1) It is necessary for the intake to have a closed tap instead of an open tap so that it

becomes a pressure intake when the river water level rises.

2) The intake should be placed at a right angle to the river flow direction wherever

possible so that the head of the approaching velocity at the time of flooding is

minimized.

3) As water inflow at the time of flooding exceeds the design discharge, the spillway

capacity at the settling basin or starting point of the headrace should be fairly

large.

Angularity Haunch Rounded

Bellmouth Protruding

f = 0.1 (round) - 0.2 (orthogon)

f = 0.5 f = 0.25

f = 0.05 – 0.01 f = 0.1 f = 0.5 + 0.3 cosθ + 0.2 cos2θ

θ


-5- 14-

5.4 Settling Basin

The settling basin must have a structure that is capable of settling and removing

sediment with a minimum size that could have an adverse effect on the turbine and also

have a spillway to prevent inflow of excess water into the headrace. The basic

configuration of a settling basin is illustrated below.

Fig.5.4.1 Basic configuration of settling basin

[Reference]

For rectangular section of the channel, uniform flow depth:

ho11=H*×0.1／(SLs)0.5

H* : refer to {Ref.5-1}

1 : ho1 is calculated based on Mainng Formulae. In here, a simple method for calculation for ho1 is indicated..

Conduit sectionWidening section

Settling section

Bb

1.0

2.0

Dam

SpillwayStoplog Flushing gate

Intake

Headrace

Bsp

hs

hsp+

15cm

h0

10～

15ｃｍ

hi

ic=1/20～1/30

IntakeStoplog

bi

ＬｃＬｗＬｓ

Ｌ

Sediment PitFlushing gate


-5- 15-

SLs : slope of top end of the headrace

ho2={(α×Qd2)/(g×B2)}1/3

α=1.1

Qd= Design Discharge (m3/s)

g=9.8

B:Width of Headrace (m)

if ho1<ho2, ho=ho1

if ho1≦ho2, ho=ho2

Each of these sections has the following function.

(1) Conduit section

Conduit section connects the intake with the settling basin. The length of the conduit

section should be minimized.

(2) Widening section:

This section regulates water flow from the conduit channel to prevent the occurrence of

whirlpools and turbulent flow and reduces the flow velocity inside the settling basin to a

predetermined velocity.

(3) Settling section:

This section functions to settle sediments/grains size of 0.5 – 1 mm. Theminimum

length (l) is calculated by the following formula based on the relation between the

settling speed (U), flow velocity in the settling basin (V) and water depth (hs).

The length of the settling basin (Ls) is usually determined so as to incorporate a margin

to double the calculated length by the said formula.

Where,

l : minimum length of settling basin (m)

hs : water depth of settling basin (m) ( -see Fig.5.31)

U : marginal settling speed for sediment to be settled (m/s)

usually around 0.1 m/s for a target grain size of 0.5 – 1 mm.

l ×hs L s= 2×l V

U


-5- 16-

V : mean flow velocity in settling basin (m/s)

usually around 0.3 m/s but up to 0.6 m/s is tolerated in the case where the

width of the settling basin is restricted.

V = Qd/(B×hs)

Qd: design discharge (m3/s)

B : width of settling basin (m)

(4) Sediment pit:

This is the area in which sediment is deposited.

(5) Spillway

Spillway drains the submerged inflow which flows from the intake. The sizes of

spillway will be decided by following equation.

Ｑｆ= C×Bsp×hsp1.5 →hsp={Qf /(C×Bcp)}1/1.5

Where,

Qf : inflow volume of submerged orifice (m3/s, see Chapter 5-5.2.2 (1))

C : coefficient =1.80

hsp: water depth at the spillway (m, see Fig 5.3.1)

Bsp: width of the spillway (m, see Fig.5.3.1)


-5- 17-

5.5 Headrace

5.5.1 Types and Structures of Headrace

Because of the generally small amount of water conveyance, the headrace for a small-

scale hydropower plant basically adopts an exposed structure, such as an open channel

or a covered channel, etc. Some examples and their basic structures are given in Table

5.5.1 and Table 5.5.2 respectively.


Table 5.5.1 Types of headraces for small-scale hydropower plants

Type Outline Drawing Advantages and Problems Typical Structure

Open channel < Advantages > Relatively inexpensive Easy construction < Problems > Possible inflow of sediment from

the slope above High incursion rate of fallen leaves,

etc.

Simple earth channel Lined channel (dry or wet

masonry lining; concrete lining) Fenced channel (made of wood,

concrete or copper) Sheet-lined channel Half-tube channel (corrugated

piping, etc.)

Closed conduit / Covered channel

< Advantages > Generally large earth work volume Low incursion rate of sediment and

fallen leaves, etc. into the channel < Problems > Less easier channel inspection,

maintenance work, including sediment removal, and repair

Buried tube (Hume, PVC or FRPM)

Box culvert Fenced channel with cover

-5- 18 -


- 5-19 -

Table 5.5.2 Basic structure of headraces for small-scale hydropower plants

Type Outline Diagram Advantages and Problems

Simple earth channel

< Advantages > Easy construction Inexpensive Easy repair < Problems > Possible scouring or collapse of the

walls Not applicable to highly permeable

ground Difficult to mechanise the sediment

removal work Lined channel (rock and stone)

< Advantages > Relatively easy construction Can be constructed using only local

materials High resistance to side scouring Relatively easy repair < Problems > Not applicable to highly permeable

ground

Wet masonry channel

< Advantages > Local materials can be used Strong resistance to back scouring Can be constructed on relatively high

permeable ground. Easy construction at the curved

section due to the non-use of forms < Problems > More expensive than a simple earth

channel or dry masonry channel (rock/stone-lined channel)

Relatively takes labour hours. Concrete channel

< Advantages > High degree of freedom for cross-

section design < Problems > Difficult construction when the inner

diameter is small Relatively long construction period

n=0.030

n=0.025

Plastered : n=0.015

Non Plastered : n=0.020

n=0.015


- 5-20 -

Type Outline Diagram Advantages and Problems

Wood fenced channel

< Advantages > Less expensive than a concrete

channel Flexible to allow minor ground

deformation < Problems > Limited use with earth foundations Unsuitable for a large cross-section Difficult to ensure perfect water-

tightness Liable to decay

Box culvert channel

< Advantages > Easier construction than a Hume pipe

on a slope with a steep cross-sectional gradient

Relatively short construction period and applicable to a small cross-section when ready-made products are used

Rich variety of ready-made products < Problems > Heavy weight and high

transportation cost when ready-made products are used

Long construction period when box culverts are made on site

Concrete pipe channel

< Advantages > Easy construction on a gently sloping

site Relatively short construction period High resistance to external pressure Applicable to a small cross-section Elevated construction with a short

span is possible < Problems > Heavy weight and high

transportation cost

n=0.015

n=0.015

n=0.015


- 5-21 -

5.5.2 Determining the Cross Section and Longitudinal Slope

The size of cross section and slope should be determined in such a matter that the

required turbine discharge can be economically guided to the head tank. Generally, the

size of cross section is closely related to the slope. The slope of headrace should be

made gentler for reducing head loss (difference between water level at intake and at

head tank) but this cause a lower velocity and thus a lager cross section. On the contrary,

a steeper slope will create a higher velocity and smaller section but also a lager head

loss.

Generally, in the case of small-hydro scheme, the slope of headrace will be determined

as 1/500 – 1/1,500. However in the case of micro-hydro scheme, the slope will be

determined as 1/50 – 1/500, due to low skill on the survey of levelling and construction

by local contractor.

The cross section of headrace is determined by following method.

(1) Method of calculation

Qd= A ×R 2/3×SL 1/2 ／n

Qd : design discharge for headrace (m3/s)

A : area of cross section (m2)

R : R=A／P (m)

P : length of wet sides/ Wetted perimeter (m) refer to next figure.

h

b

A

bLength of red-line : P

1

m

Slope =1/m: SL

Q

Slope of headrace SL Wetted perimeter


- 5-22 -

SL : longitudinal slope of headrace (e.g. SL= 1/100=0.01)

n : coefficient of roughness (see Table 5.4.2)

For instants, in the case of rectangular cross section, width (B)=0.6m, water depth

(h)=0.5m, longitudinal slope (SL)=1/200=0.005, coefficient of roughness (n)=0.015.

A= B×h = 0.6 × 0.5 = 0.30 m2

P= B + 2 × h = 0.6 + 2 × 0.5 =1.60 m

R= A／P = 0.30／1.60 = 0.188 m

∴ Qd= A ×R 2/3×SL1/2 ／n = 0.30 ×1.60 2/3×0.005 1/2 ／0.015 = 1.94 m3/ｓ

(2) Simple method

In order to simplify the above method, following method for determining the cross

section is perpetrated in [Reference 5-1 Simple Method for Determining the Cross

Section]

This reference will be used in determination of cross section in following two sectional

forms.

Rectangular cross section Trapezoid cross section

H* should be calculated on each different slopes. For instants, in the case of trapezoid

cross section, design discharge (Q)=0.5m3/s, width (B)=0.8m, longitudinal slope

(SLA,B,C,D)=1/100, 1/50, 1/100, 1/200 which is the gentlest potion of the headrace,

coefficient of roughness (n)=0.015.

Water depth (H*) is approximately 0.3m in Reference 5-1 Fig-4. Therefore actual water

depth (H) is

H = H* × 0.1 ／(SL)0.5

HA,C = H* × 0.1 ／(SLA,C)0.5 = 0.3×0.1／(0.01) 0.5 = 0.3

HB = H* × 0.1 ／(SLB)0.5 = 0.3×0.1／(0.02) 0.5 = 0.21

HD = H* × 0.1 ／(SLD)0.5 = 0.3×0.1／(0.005) 0.5 = 0.42

and height of the cross section of Slope A,C is 0.60m(0.3+0.2～0.3),

B=0.6 and 0.8m

1.0

m=0.5 B=0.6 and 0.8m


- 5-23 -

height of the cross section of Slope B is 0.55m(0.21+0.2～0.3),

height of the cross section of Slope D is 0.75m(0.42+0.2～0.3).

Slope A Slope B

Slope C

Slope D

SLA = 1/100

SLB = 1/50 SLC = 1/100

SLD = 1/200


- 5-24 -

5.6 Headtank

5.6.1 Headtank Capacity

(1) Function of headtank

The functions of headtank are roughly following 2 items.

Control difference of discharge in a penstock and a headrace cause of load

fluctuarion.

Finally remove litter (earth and sand, driftwood, etc.) in flowing water

(2) Definition of headtank capacity

The headtank capacity is defined the water depth from hc to h0 in the headtank length L

as shown in Fig.5.6.1.

Fig.5.6.1 Picture of headtank capacity

0.5

1.0

dsc

As

d

Bspw

hc

h0

h>1.0×ｄ

S=1～2×ｄ

1.0

20.0

Ｂ

Ｌ

1.02.0

30～50cm

ｂ

B-b

Headrace

30～50cm

Ht

Spillway

Screen

SLe

h0=H*×0.1／（Sle）0.5　H*：Refer to 'Reference 5-1'

hc=｛(α×Qd2)／(ｇ×B2)}1/3　　　α=1.1　g=9.8

d=1.273×(Qd／Vopt）0.5

　 Vopt:Refer to 'Reference 5-2'Vsc=As×dsc=B×L×dsc≧10sec×QdB,dsc:desided depend on site condition.


- 5-25 -

Headtank capacity Vsc = As×dsc＝B×L×dsc

where, As: area of headtank

B : width of headtank

L : length of headtank

dsc: water depth from uniform flow depth of a headrace when using

maximum discharge (h0) to critical depth from top of a dike for sand

trap in a headtank (hc)

[Refference]

In oblong section, uniform flow depth: ho=H*×0.1／(SLe)0.5

H* : refer to {Ref.5-1}

SLe : slope of tail end of the headrace

critical depth: hc={(α×Qd2)／(g×B2)}1/3 α: 1.1 g : 9.8

(3) Determine a headtank capacity

The headtank capacity should be determined in consideration of load control method

and discharge method as mentioned below.

a. In case only the load is controlled

The case only control load (demand) fluctuation is considered, a dummy load

governor is adopted. A dummy load governor is composed of water-cooled heater

or air-cooled heater, difference of electric power between generated in powerhouse

and actual load is made to absorb heater. The discharge control is not performed.

The headtank capacity should be secured only to absorb the pulsation from

headrace that is about 10 times to 20 times of the design discharge (Qd).

A view showing a frame format of load controlled by a dummy load governor is

shown in Fig.5.6.2.

Fig.5.6.2 Pattern diagram of dummy load consumption

Generated power

Dummy load consumption

Time

Power demand

Ele

ctri

c po

wer

Wat

er d

isch

arge


- 5-26 -

b. In case both load and discharge is controlled

In the case of controlled both load and discharge, it used for load control a

mechanical governor or electrical governor. These governors have function of

control vane operation to optimal discharge when electrical load has changed.

Generally a mechanical governor is not sensitive response to load change,

headtank capacity in this case should be secured 120 times to 180 times of Qd.

On the other hand, an electrical governor will response of load change, therefore

headtank capacity is usually designed about 30 times to 60 times of Qd.

5.6.2 Important Points for Headtank Design

The design details for the headtank for a small-scale hydropower plant are basically the

same as those for a small to medium-scale hydropower plant and the particularly

important issues are discussed below.

(1) Covering water depth and installation height of penstock inlet

As the penstock diameter is generally small (usually 1.0 m or less) in the case of a

small-scale hydropower plant, it should be sufficient to secure a covering water depth

which is equal to or larger than the inner diameter of the penstock. However, in the case

of a channel where both the inner diameter and inclination of the penstock are as large

as illustrated below, the occurrence of inflow turbulence has been reported in the past.

Accordingly, the covering water depth must be decided with reference to the illustration

below when the inner diameter of the penstock exceeds 1.0 m.

Vertical angle

Swirly when Qmax


- 5-27 -

h = d2

Where,

h : water depth from the centre of the inlet to the lowest water level of the

headtank = covering water depth (m)

d : inner diameter of the penstock (m)

Covering Water Depth

The covering water depth at the penstock inlet must be above the following value

to prevent the occurrence of inflow turbulence.

d 1.0 m h 1.0 d

d > 1.0 m h d2

Where,

h : water depth from the centre of the inlet to the lowest water level of the

headtank = covering water depth (m)

d : inner diameter of the penstock (m)

Installation height of penstock

There are many reports of cases where inappropriate operation has caused the

inflow of sediment into the penstock, damage the turbine and other equipment.

Accordingly, it is desirable for the inlet bottom of the penstock to be placed

slightly higher than the apron of the headtank (some 30 – 50 cm).

NWL

LWL

h

30～50cm d

1～2d


- 5-28 -

(2) Appropriate spacing of screen bars for turbine type, etc.

The spacing of the screen bars (effective screen mesh size) is roughly determined by the

gate valve diameter but must be finalised in consideration of the type and dimensions of

the turbine and the quantity as well as quality of the litter. The reference value of an

effective screen mesh size is shown below.

Effective screen mesh size (reference)

(3) Installation of vent pipe to complement headtank gate

When a headtank gate is installed instead of a gate valve for a power station, it is

necessary to install a vent pipe behind the headtank gate to prevent the rupture of the

penstock line.

In this case, the following empirical formula is proposed to determine the dimensions of

the vent pipe.

Where,

d : inner diameter of the vent pipe (m)

P : rated output of the turbine (kW)

L : total length of the vent pipe (m)

H : head (m)

200 400 600 800 1000

20

50

Gate Valve Diameter (mm)

Effective Screen Mesh Size (mm)

d = 0.0068 ( ) 0.273 P2・L

H2


- 5-29 -

Source: Sarkaria, G.S., “Quick Design of Air Vents for Power Intakes”, Proc. A.S.C.E.,

Vol. 85, No. PO.6, Dec., 1959

(4) Spillway at the headtank

Generally, the spillway will be installed at the headtank in order to release eexcess

water is discharged to the river safely when the turbine stopped it.

The sizes of spillway are decided by following equation.

Qd=C×Bspw×hspw1.5 → hspw={Qd／(C×Bspw)}1/1.5

Qd : design discharge (m3/s)

C : cofficient, usually C=1.8

Bspw : width of spillway (m , refer to Fig 5.1.1)

hspw : depth at the spillway (m)


- 5-30 -

5.7 Penstock

5.7.1 Penstock Material

At present, the main pipe materials for a penstock are steel, ductile iron and FRPM

(fibre reinforced plastic multi-unit). In the case of a small-scale hydropower plant, the

use of hard vinyl chloride, Howell or spiral welded pipes can be considered because of

the small diameter and relatively low internal pressure. The characteristics of each pipe

material are shown in “Table 5.7.1 – Penstock pipe materials for small-scale

hydropower plant”.

5.7.2 Calculation of Steel Pipe Thickness

The minimum thickness of steel pipe of penstock is determined by following formula.

where, t0: minimum thickness of pipe

P: design water pressure i.e. hydrostatic pressure + water hammer

(kgf/cm2) , in micro-hydro scheme P=1.1×hydrostatic pressure.

for instance, if the head (Hp, refer to following figure) which from

headtank to turbine is 25m, P=2.5×1.1=2.75 kgf/cm2.

d: inside diameter (cm)

θa: admissible stress (kgf/cm2) SS400: 1300kgf/cm2

η: welding efficiency (0.85～0.9)

δt : margin (0.15cm in general)

5.7.3 Determining Diameter of Penstock

Generally the diameter of penstock is determined by comparison between the cost of

penstock and head loss at penstock. However a simple method for determining the

diameter of penstock indicated in [Reference 5-2 Simple Method for Determining the

Diameter of Penstock] .

The diameter of penstock will be determined from “Average angle of Penstock (Ap: see

following figure) “ and “Design Discharge (Qd)”.

t0 = + δt (cm) P×d

2×θa×η and t0=≧0.4cm or t0≧(d+80)／40 cm


- 5-31 -

For instances like in the design discharge (Qd)=0.50m3/s,length of penstock (Lp)=60m,

height from head tank to power house (Hp)=15m, average angle (Ap)=15/60=0.25, the

optimum velocity (Vopt) is determined as about 2.32 in Reference 5-2. Therefore the

diameter of penstock pipe (d) is

d = ( × Qd／Vopt)0.5 =(1.273 × 0.5／2.32)0.5 = 0.52 m

Lp

Head Tank

Power House

Hp

Ap = Hp ／ Lp

4

3.142


Table 5.7.1 Penstock pipe materials for small-scale hydropower plant

Resin Pipe Iron Pipe

Hard Vinyl Chlorid Pipe

Howell Pipe FRP Pipe Steel Pipe Ductile Iron Pipe Spiral Welded Pipe

Characteristics Most popular material for a pipeline as it is frequently used for water supply and sewer lines

Effective for a pipeline with a small discharge

Rich variety of ready-made irregular pipes

Often buried due to weak resistance to impact and large coefficient of linear expansion

Basically resistant to external pressure but ready-made pipes to resist internal pressure are available

Relatively easy fabrication of irregular pipes due to easy welding

Basically used as a buried pipe

Plastic pipe reinforced by fibre glass

Used as an exposed pipe and can be made lighter than FRPM pipe with a thinner wall as it is not subject to external load other than snow

Popular choice to penstock at a hydropower plant

Reliable material due to established design techniques

Often used for water supply, sewer, irrigation and industrial pipes

Generally used as a buried pipe although exposed use is also possible

High resistance to both external and internal pressure

Some examples of use for a pipeline

Mainly used as a buried pipe for appearance to hide a spiral welding line

Can be used as steel pipe piles

Maximum Pipe Diameter (mm)

Thick pipe: 300 Thin pipe: 800

2,000 3,000 approx. 3,000 2,600 2,500

Permissible Internal Pressure (kgf/cm2)

Thick pipe: 10 Thin pipe: 6

2.0 – 3.0 Class A: 22.5 133 approx. 40 15

Hydraulic Property (n)

0.009 – 0.010 0.010 – 0.011 0.010 – 0.012 (approx. 0.011 in general)

0.010 – 0.014 (approx. 0.012 in general)

0.011 – 0.015 (approx. 0.012 in general)

-

-5-32 -


Resin Pipe Iron Pipe

Hard Vinyl Chlorid Pipe

Howell Pipe FRP Pipe Steel Pipe Ductile Iron Pipe Spiral Welded Pipe

Workability Easy design and work due to light weight and rich variety of irregular pipes

Good workability due to light weight

Good workability due to light weight and no need for on-site welding as a specially formed rubber ring is used for pipe connection

Steel pipes are used for irregular sections because of the limited availability of irregular FRP pipes

Inferior workability to FRP pipes



Water-tightness Good water-tightness as bonding connection is possible

No problem of water-tightness at the joints

No problem of water-tightness as the joint connection method is established

No problem of water-tightness as the joint connection method is established

Good No problems

-5-33-


-5-34-

5.8 Foundation of Powerhouse

Powerhouse can be classified into ‘the above ground type’, the semi-underground

type’ and ‘the under ground type’. Most of small-scale hydropower plants are of ‘the

above ground type’

The dimensions for the floor of powerhouse as well as the layout of main and

auxiliary equipment should be determined by taking into account convenience during

operation, maintenance and installation work, and the floor area should be effectively

utilized.

Various types of foundation for powerhouse can be considered depending on the type

of turbine. However the types of foundation for powerhouse can be classified into ‘for

Impulse turbine’ (such as Pelton turbine, Turgo turbine and Crossflow turbine) and

‘for Reaction turbine’ (Francis turbine, Propeller turbine).

5.8.1 Foundation for Impulse Turbine

Figure 5.8.1 shows the foundation for Crossflow turbine which frequently is used in

the micro-hydro scheme as an impulse turbine. In case of impulse turbine, the water

which passed by the runner is directly discharged into air at tailrace. The water

surface under the turbine will be turbulent. Therefore the clearance between the slab

of powerhouse and water surface at the afterbay should be kept at least 30-50cm. The

water depth (hc) at the afterbay can be calculated by following equation.

hc: water depth at afterbay (m)

Qd: design discharge (m3/s)

b : width of tailrace channel (m)

The water level at the afterbay should be higher than estimated flood water level.

Then in case of impulse turbine, the head between the center of turbine and water

level at the outlet became head-loss(HL3:refer to Ref.5-3).

hc= { (( )1/3 }1/3 1.1×Qd2

9.8×b2


-5-35-

Fig.5.8.1 Foundation of Powerhouse for Impulse Turbine (Crossflow turbine)

5.8.2 Foundation for Reaction Turbine

Figure 5.8.2(a) shows the foundation for Francis turbine which is a typical turbine of

the reaction turbine. The water is discharged into the afterbay through the turbine.

In case of reaction turbine, the head between center of turbine and water-level can be

use for power generation. Then it is possible that turbine is installed under flood

water level on condition to furnish the following equipment.(see Fig.5.7.2(b))

a. Tailrace Gate

b. Pump at powerhouse

Flood Water Level(Maximum)

20cm

boSection A-A

20cm

b

bo: depends on Qd and He

30～50cm

ｈｃ

30～50cm

HL3

(see Ref.5-3)

hc={ }1/31.1×Qd2

9.8×ｂ２

A

A

Afterbay Tailrace cannel Outlet


-5-36-

Fig 5.8.2(a) Foundation of powerhouse for Reaction Turbine (Francis turbine)

Fig 5.8.2(b) Example of Installation to Lower Portion

Section A-A

1.5×d3

Flood Water Level(Maximum)30～50cmｈｃ

2×ｄ3

d3

20cm

1.15×d3

1.5×d3

Hs

Hs：depens on characteristic of turbine

HL3

(see Ref.5-3)

hc={ }1/31.1×Qd2

9.8×ｂ２

A

A

Pump

Gate

HL3

Flood Water Level (Maxmum)


-5- 37-

[Ref. 5-1 Simple Method for Determining the Cross Section]

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Turbine Discharge Q (m3/s)

Wat

er D

epth

Dam

my

H*

(m)

n=0.015

n=0.020

n=0.025

n=0.030

H

0.2～0.3m

0.6m

H=H*×0.1/(SLmin)0.5

Fig.1 Determining the Cross Section of Headrace

Rectangular Form (B=0.6m)


-5- 38-

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1


Wat

er D

epth

Dam

my

H*

(m)

n=0.015

n=0.020

n=0.025

n=0.030

H

0.2～0.3m

0.8m

H=H*×0.1/(SLmin)0.5


Rectangular Form (B=0.8m)


-5- 39-


Trapezoid Form (B=0.6m)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1


Wat

er D

epth

Dam

my

H*

(m)

n=0.015

n=0.020

n=0.025

n=0.030

H

0.2～0.3m

0.6m

H=H*×0.1/(SLmin)0.5

1:0.5


-5- 40-


Trapezoid Form (B=0.8m)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1


Wat

er D

epth

Dam

my

H*

(m)

n=0.015

n=0.020

n=0.025

n=0.030

0.2～0.3m

H

0.8m

H=H*×0.1/(SLmin)0.5

1:0.5

0.2-0.3


-5- 41-

[Ref.5-2 Simple Method for Determining the Diameter of Penstock]

0.500.600.700.800.901.001.101.201.301.401.501.601.701.801.902.002.102.202.302.402.502.602.702.802.903.003.103.20

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40

Average angle of penstock Ap

Opt

imum

vel

ocit

y V

opt (

m/s

)

D=1.273×(Q／Vopt)0.5

D:　diameter of pipe(m)

Q: design discharge(m3/s)Vopt: optimum velocity(m/s)

Graph to Determine the Diameter of Penstock Pipe

(1.273 x Q x Vopt) 0.5


-5-42-

[Ref. 5-3 Calculation on Head Loss]

Head losses are indicated by the figure of hydropower system below. HL1 can be

calculated easily as the differential water level between the intake to the forebay

tank. Similarly HL3 can be calculated as differential level between the center of

turbine to the tailrace.

He = Hg – (HL1 + HL2 + HL3 )

Where: He - Effective Head

Hg - Gross Head

HL1 - Loss from intake to forebay

HL2 - Loss at penstock

HL3 - Installation head and Loss at tailrace

Then HL2 can be calculated by the following equations.

(1) Friction loss

Friction loss (Hf) is one of the biggest losses at penstock.

Hf = f ×Ｌp×Ｖp2 ／（2×g×Ｄp）

Where:

Hf - Friction loss at penstock (m)

f - Coefficient on the diameter of penstock pipe (Dp).

f= 124.5×n2／Dp1/3

Lp - Length of penstock. (m)

Hg He

HL1 HL2

HL3

Forebay

Penstock

Settling Basin

Headrace Intake

Powerhouse Tailrace

H


-5-43-

Vp - Velocity at penstock (m/s)

Vp = Q ／ Ap

g = 9.8

Dp - Diameter of penstock pipe (m)

n = Coefficient of roughness (steel pipe: n=0.12, plastic pipe:

n=0.011)

Q - Design discharge (m3/s)

Ap - Cross sectional area of penstock pipe. (m2)

Ap = 3.14×Dp2／4.0

(2) Inlet Loss

he = fe × Vp ／(2×g)

he - Inlet loss (m)

fe - Coefficient on the form at inlet. Usually fe = 0.5 in micro-hydro

scheme.

(3) Valve Loss

hv = fv × Vp ／(2×g)

hv - Valve loss (m)

fv - Coefficient on the type of valve.

fv = 0.1 ( butterfly valve)

(4) Others

“Bend loss” and “Loss on the change of cross sectional area” are considered as

other losses. However these losses can be neglected in micro-hydro scheme.

Usually the planner of micro-hydro scheme must take into account the

following margin as other losses.

ho = 5～10％×( hf + he +hv )


- 6-1 -

Chapter 6 DESIGN FOR MECHANICAL AND ELECTRICAL STRUCTURES

6.1 Fundamental Structure of Equipment for Power Plant

The fundamental equipment and facilities briefly discussed in the preceding chapters are

tackled in more detailed manner in this chapter. In addition, the summary of

micro-hydropower generating equipment for rural electrification is also presented herein

for quick reference.

Summary of Micro Hydropower Turbines for Rural Electrification in the

Philippines

1. Fundamental Conditions

The following conditions are necessary for rural electrification in the Philippines:

1) Stable operation for long term

2) Easy operation by semi-skilled operator(s) or villager(s)

3) Locally made turbines for easier maintenance and repair (except small parts)

4) Cheaper cost of equipment including installation

5) Acceptable technical guarantees of the turbine.

Table 6.1.1 Recommended Micro Hydropower Generating Equipment

Discription Synchronous Generator with Cross flow type Turbine

Asynchronous Generator with Reverse Pump type Turbine(PAT)

Advantages/Disadvantages Advantage *Very reliable power source with

stable frequency & voltage for independent network. *Machine suitable to any actual site condition can be designed and manufactured.

*Lower cost if a pump with motor suitable for site design condition is found. *Construction of machine is simple.

Disadvantages *A little higher cost than PAT

*Difficulty to select a suitable pump with motor at market *No control of voltage * Short life time of capacitors for this system

Technical aspect Net head Hn 4 – 50 m 4 - 20 m Water flow (discharge) Q 0.1 - 0.8 m3/s (Discharge is a little

variable) 0.04 - 0.13 m3/s (discharge shall be kept always constant )

Turbine output at turbine shaft

Pt 10 – 250 kW Pt =0.98 x Hn x Q x t (t= 0.7)

2 – 7 kW Pt =0.98 x Hn x Q x p

(p= t =0.65)


- 6-2 -

Pump efficiency(p) is too variable due to change of discharge, the pump with induction motor of nearly same head and same discharge shall be selected.

Power transmitter Belt coupling for speed matching between turbine and generator m : Efficiency of transmitter

Direct coupled without transmitter

Dummy load type governor ELC controller with thyristor IGC controller with transistor Generator output at generator terminal

Pg 8.5 – 210 kW Pg= Pt x g x m (g = 0.88, m =0.97) (coupled with transmitter)

1.5 – 5.3 kW Pg = Pt x g (g = 0.75)

Rated output of generator (kVA) to be applied

Pk

VA PkVA Pg /0.8 (PF= 0.8) The generator with rated output of more than Pg /0.8 shall be selected.

The induction motor originally coupled with the pump shall be used as induction generator by adding separate capacitors

Rotation speed 1500 rpm 1515 – 1525 rpm due to speed of induction motor as generator

Voltage 380/220V, star connection Stable with AVR on generator

380/220V, star connection Voltage control cannot be made without AVR

Frequency 50 Hz, Stable 50.5 – 50.75 Hz Not so stable Dummy Pd Air heaters (Pd = Pg x SF), SF=1.3 Air heaters (Pd = Pg x SF), SF=1.3 Inlet valve Butterfly valve (It is not provided

for cost saving sometime, but it’s better to be provided for complete stop of turbine)

Same as left, but it is neglected in case of small capacity.

The following equipment and facilities are necessary as fundamental structure of power

plant, details of which are shown in Table 6.1.2

Equipment & Facility Purpose & Function

1. Inlet valve: To control the stop or supply of water to turbine from

penstock.

2. Water turbine: To change the energy of water to the rotating power.

3. Governor of turbine: To control the speed and output of turbine

4. Power transmission facility: To transmit the rotation power of turbine to generator.

5. Generator: To generate the electricity from turbine or its transmitter

6. Control and protection panel: To control and protect the above facilities for safe operation

7. Switchgear (with transformer): To control on/off operation of electric power and step-up the

voltage of transmission lines (if required)

Note: The above items 3, 6 & 7 may sometimes be combined in one panel for micro-hydro power

plant.

Note: t, m, g and SF are fixed only for brief checking. In case of detail design, it is recommended to check the

efficiency of each machine and facility.


- 6-3 -

Table 6.1.2 Composition of Fundamental Equipment for Hydraulic Power Station

Equipment Type Control Method Inlet valve Butterfly valve

Bi-plane butterfly valve Sluice valve Needle valve

Hand operated type Motor operated type Counter weight type

Turbine Crossflow Reverse Pump H-shaft Pelton Turgo-Pelton Propeller H-shaft Francis Tubular

Dummy load type Oil pressure type Motor operated type Manual operated type Non-controlled type

Power transmission facility (Speed increaser)

Fixed coupling Flexible coupling Belt coupling Gear coupling

Generator Synchronous Induction Self-excitation Induction

Manual AVR APFR

Control & Protection panels

Wall mounted Self stand open type Self stand sealed type

Control switches, Main switches IC panels Relays

Power Transformer Oil immersed, self cooling, single or 3-phase, pole transformer


- 6-4 -

1

10

100

40 50 60 70 80 90 100 110 120 130 140

Discharge (l/s)

Net

Hea

d (m

)

7 kW6 kW

5 kW

4 kW3 kW2 kW

20

4

50

Figure 6.1.2 (b) Applicable limit of PAT at Turbine Shaft

Discharge Q [l/s]

Figure 6.1.2 (a) Applicable of Crossflow and PAT at Turbine


- 6-5 -

6.2 Turbine (Water Turbine)

6.2.1 Types and Output of Water Turbine

The types of water turbine are mainly classified into two types with some

additional classification as follows:

1 Impulse turbine Pelton turbine

Crossflow turbine

Turgo-impluse turbine

2 Reaction turbine Francis turbine

Propeller turbine Kaplan turbine

Diagonal mixed flow

Tubular turbine

Straight flow turbine turbine (Package

type )

Note:

1) Impulse turbine: Turbine type that rotates the runner by the impulse of water jet

having the velocity head which has been converted from the

pressure head at the time of jetting from the nozzle.

2) Reaction turbine: Turbine construction that rotates the runner by the pressure

head of flow.

Shaft arrangement: The arrangement of turbines will be also classified into two

types, i.e. “Horizontal shaft (H-shaft)” and “Vertical shaft

(V-shaft)”

Referring to the required output, available net head and water flow (discharge), the

following types of turbine may be applicable for micro or small hydraulic power

plant of rural electrification.

(1) Horizontal Pelton turbine

(2) Horizontal Francis turbine

(3) Crossflow turbine

(4) Tubular turbine S-type tubular turbine

Vertical tubular turbine

Runner rotor integrated turbine

Vertical propeller turbine

Horizontal propeller turbine


- 6-6 -

(5) Turgo impulse turbine

(6) Reverse pump turbine Vertical propeller type

Horizontal propeller type

Submerged pump type

The output of turbine is calculated with following formula:

Pmax = 9.8 x He x Qmax x t

Pmax : Maximum output (kW)

He : Net head (m)

Qmax : Maximum discharge (m3/s)

t : Maximum turbine efficiency (%) Please refer to chapter 6.2.2

The brief characteristics, explanation and drawing of each type are shown in Table 6.2.1.

The applicable range of each type turbine is shown in Figure 6.2.1.

Referring to the said table and figure, the customer can select the type of turbine, which

is most suitable to the actual site condition including the total cost of civil work and

equipment.

At present, however, it is recommended to apply “Crossflow turbine”, which are

designed and manufactured locally, because the proper design of “Crossflow turbine”

can be achieved by applying available model test data and the cost is comparably low.

The reverse pump may also be used as reverse pump turbine by reversing the direction

of rotation, if the characteristic of water pump, which is available in market, is matched

almost strictly to that of the turbine required from the site condition (head, water

discharge, output, efficiency, rotation speed etc.).

However, as the site condition of each power plant is not always the same and the

matching of characteristics of pump and proposed turbine is difficult, the selection of

standard pump for turbine shall be made carefully and circumspectly. In case the

characteristics are well matched between pump and turbine, the application of reverse

pump turbine is recommended and the cost of such machine will be cheaper.

In the future, other types of turbine will be selected widely because other types of

turbines may also be manufactured locally with proper design and fabrication capability.


- 6-7 -

Figure 6.2.1 Applicable Type (Selection) of Turbines


- 6-8 -

6.2.2 Specific Speed and Rotational Speed of Turbine

The specific speed is the ratio between the rotational speeds of two runners

geometrically similar to each other, which derived from the conditions of the laws of

similarity, and specific speed of similar runners in a group by the rotational speed

obtained when one runner has effective head H = 1m and output P = 1kW.

It may be understood that the specific speed is a numerical value expressing the

classification of runners correlated by three factors of effective head, turbine output and

rotational speed as follows:

Ns = (N x P1/2)/ H5/4 N = (Ns x H5/4 )/ P1/2

Where, Ns; Specific speed (m-kw)

N; Rotational speed of turbine (rpm)

P; Output of turbine (kW) = 9.8 x Q x H x

H; Effective head (m)

Q; Discharge (m3/s)

; Maximum efficiency (%, but a decimal is used in calculations)

= 82 % for Pelton turbine

= 84 % for Francis turbine

= 77 % for Crossflow turbine*

= 84 % for S-type tubular turbine

Note: * 40-50% should be applied for Crossflow type turbine manufactured locally at

present stage because due to fabrication quality.

The specific speed of each turbine is specified and ranged according to the construction

of each type on the basis of experiments and actual proven examples.

The limitation of specific speed of turbine (Ns-max) can be checked in following

formula.

Pelton turbine: Ns-max ≦ 85.49H-0.243

Crossflow turbine: Ns-max ≦ 650H-0.5

Francis turbine: Ns-max ≦ (20000/(H+20))+30

Horizontal Francis turbine: Ns-max ≦ 3200H-2/3

Propeller turbine: Ns-max ≦ (20000/(H+20))+50

Tubular turbine Ns-max ≦ (20000/(H+16))

The range of specific speed of turbine is also shown in Figure 6.2.2


- 6-9 -

Figure 6.2.2 Range of specific speed by turbine type

Specific speed (m-kW)200 400 600 800

Pelton turbine 1 2≦ Ns ≦ 25

Francis turbine 60 ≦ Ns ≦ 300

Cross flow turbine 40 ≦ Ns ≦ 200

Propeller turbine 250 ≦ Ns ≦ 1000

10000


- 6-10 -

Tab

le 6

.2.1

Kin

ds a

nd

Ch

arac

teri

stic

s fo

r ea

ch T

ype

of W

ater

Tu

rbin

e pa

ge 1


- 6-11 -

Tab

le 6

.2.1

Kin

ds a

nd

Ch

arac

teri

stic

s fo

r ea

ch T

ype

of W

ater

Tu

rbin

e pa

ge 2


- 6-12 -

6.2.3 Design of Crossflow Turbine

Brief design of Crossflow turbine T-13 and T-14, designed and manufactured in

Indonesia according to appropriate design data, is shown hereunder. The detailed design

shall be referred to the design sheet from the manufacturer. The design shall be

conducted in the following procedures:

1 Get the basic data for rated water flow (m3 /s), elevations (m) of water level at

forebay and turbine center (or tailrace water if designed as special case) from civil

design.

2 Calculate net head from gross head by deducting head loss of penstock (friction

and turbulence).

3 Estimate the net hydraulic power and turbine shaft output from water flow, net

head and turbine efficiency.

4 Calculate width of turbine runner according to manufacturer’s recommendation.

5 Calculate the mechanical power to generator from efficiency of power transmitter

(speed increaser)

6 Calculate rated electrical output of generator (kW). ----Maximum output of

electricity

7 Calculate the rotational speed of turbine from specific speed, turbine shaft output

(Item 3) and net head.

8 Select suitable generator available at market and its output (kVA), frequency,

voltage, power factor and rotational speed (frequency), referring to catalogue of

generator manufacturer.

9 Calculate the ratio of rated rotational speed of turbine and generator.

10 Select the width and length of belt referring to belt manufacturer’s

recommendation.

11 Calculate the capacity of dummy load and suitable ELC (Electronic Load

Controller) or IGC (Induction Generator Control) in case of induction generator.

12 Calculate the diameters of the pulley for the turbine and generator.

Notes:

Basic data of T-13 and 14 available from the model test.

Diameter of turbine: 300mm No. of runner blade: 28nos. Unit speed: 133 rpm

Detailed design shall be referred to the “Design Manual for Crossflow Turbine”

attached herewith.


- 6-13 -

6.2.4 Design of Reverse Pump Type Turbine (Pump As Turbine)

A water pump used as turbine by reversing rotation of pump is called the Pump As

Turbine (PAT).

1 To calculate and get the effective head (net head), water flow (discharge), and

net hydraulic power as same method as item 1, 2 and 3 of above Crossflow

turbine in chapter 6.2.3.

2 To check suitable pump available in the market, considering maximum

efficiency point of pump, rotation speed of motor (generator: 2, 4 or 6 poles)

because the direct coupling between turbine and generator is usually adopted for

this kind of turbine. The rotation speed shall be referred to Table 6.3.1. In case of

induction generator, the speed of turbine shall be a little higher ( i.e. 2 - 5 %)

than that of generator at rated frequency. (1,550 rpm from 1,500 rpm)

3 To select and finalize the pump as turbine, considering the maximum efficiency

point of pump, applicable efficiency for actual output of turbine shaft because

the range of high. Efficiency point of pump is very narrow.

4 The selection method shall be referred to the “Design Manual for Reverse Pump

Turbine”.


- 6-14 -

6.3 Generator

6.3.1 Type of Generator

Two kinds of generator can be adopted for generating electric power from the energy

produced by water turbines.

1. Fundamental classification of AC generator

( DC generator is not usually used for small-scale hydropower plant)

(1) Synchronous generator Independent exciter of rotor is provided for each unit

Applicable for both independent and existing power

network

(2) Induction generator No exciter of rotor is provided (squirrel cage type)

(Asynchronous) Usually applicable for network with other power source.

Sometimes applicable for independent network with

additional capacitors for less than 25 kW but not so

recommendable for independent network due to difficulty

of voltage control and life time of capacitors except cost

saving.

Shaft arrangement Either vertical shaft or horizontal shaft is applied to both

type of above generators.

(mainly horizontal high speed type in case of micro/small

plant except reverse pump turbine)

2. Another classification is also applied to AC generator as follows;

1) Three phase generator Star (λ) connection For 3 phase 4 wire network

Delta(Δ) connection For single phase 2 wire network

2) Single phase generator This type is not used in power network system because

it is difficult to purchase the generator with capacity of

more than 2kW in market. In this case three phase

generator with delta connection is applied as shown

above.

The winding connections of generator (Star and Delta ) are shown in Figure 6.3.1 as

follows:


- 6-15 -

each winding

Figure 6.3.1 Connection Diagram of Generator

The characteristic (advantage & disadvantage) of both type generators is shown in Table

6.3.1 below.

Table 6.3.1 Comparison of Synchronous generator and Induction generator

I. Advantage of Synchronous Generator Item Synchronous generator Induction generator

Independent operation Independent operation is possible No independent operation is possible since excitation from other system is required

Power factor adjustment Operation at desired power factor in response load factor is possible

Operation power factor is governed by generator output and cannot be adjustable

Excitation current DC exciter is employed. The lagging current is taken as the exciting current from the system so that the power factor of the system decreases. The exciting current increases in low speed machines.

Voltage and frequency adjustment

Adjustment is possible as desired in independent operation

Voltage and frequency adjustment is not possible. The generator is governed by the voltage and frequency of the system.

Synchronizing current Transient current and voltage drop in the system are small since the paralleling is made after synchronization.

Connection to the system to be made by forced paralleling by which a large current is created, resulting in a voltage drop in the system.

R

S

T

R

S

T Star connection Star connection


- 6-16 -

II. Advantage of Induction Generator Item Synchronous generator Induction generator

Construction The rotor has exciting winding outside the damper winding which is equivalent to the bars of squirrel-cage of induction generator. This is more complicated

The rotor is the same as a synchronous generator but the rotor is of the squirrel cage type. Thus , the construction is simple and sturdy. It can be easily correspond to operation under adverse conditions and is the best suited for small or medium capacity.

Exciter and field regulator

Required This is not required since exciting current is taken from the system

Synchronization Required. Thus, synchronism detector is necessary

No synchronizing device is required since forced paralleling is made. Rotating speed is detected and making is performed almost at synchronous speed.

Stability Pull out may occur if the load fluctuates suddenly

Stable and no pull out due to load fluctuation

High harmonic load Allowable output is required by the thermal capacity of the surface of the magnetic pole when there is no damper or when there is a damper

Heat capacity of rotor bars is large and they are relatively strong against higher harmonic load

Maintenance In addition to the items for induction generator, maintenance and inspection is required for field windings and brushes if employed.

Maintenance is required for stator, cooler and filter but not required for the rotor of squirrel-cage type.

6.3.2 Output of Generator

The output of generator is shown with kVA and calculated with following formula:

Pg (kVA) = (9.8 x H x Q x ) / pf

Where; Pg; Required output (kVA)

H; Net head (m)

Q; Rated discharge (m3/s)


- 6-17 -

; Combined efficiency of turbine, transmitter & generator (%)

= turbine efficiency (t) x transmitter efficiency (m) x generator

efficiency (g)

pf; Power factor ( % or decimal), the value is based on the type of

load in the system. If inductive load, such as electric motor, low

power factor lamps, is high in the system, the power factor is low

i.e. the generator capacity should be larger according to above

formula. However, 80% is usually applied for convenient purpose

of selection.

In case of micro hydro power plant, the rated output of generator is selected from the

standard output (kVA) with allowance from the manufacturer’s catalogue in the market.

6.3.3 Speed and Number of Poles of Generator

The rated rotational speed is specified according to the frequency (50 or 60 Hz) of

power network and the number of poles as shown in following formula

For synchronous generator

P (nos.) = 120 x f / N0 N0 (rpm) = 120 x f / P

Where, P: Number of poles (nos.)

N0: Rated rotational speed (rpm)

f : Frequency of network (Hz),

For induction generator

The speed is a little higher than that of synchronous generator for excitation with slip.

N (rpm) = (1-S) x N0

Where, N: Actual speed of induction generator

S: Slip (normally S= -0.02)

N0: Rated rotation speed

As the rotational speed is fixed with number of pole, the speed and pole number of

generator are shown in Table 6.3.1 hereunder.


- 6-18 -

Table 6.3.1 Standard Rotational Speed of Generator

Unit: rpm (min-1) No. of pole 50Hz 60Hz No. of pole 50Hz 60Hz

4 1,500 1,800 14 429 514 6 1,000 1,200 16 375 450 8 750 900 18 333 400 10 600 720 20 300 360 12 500 600 24 250 300 Note: The frequency in the Philippines is 60 Hz shall be selected from the table.

The size and cost of high speed generator is smaller and cheaper

than low speed generator.

Referring to the original turbine speed and the rated generator speed, either direct

coupling or indirect coupling with power transmission facility (gear or belt) is selected

so that the suitable ratio of speed between turbine and generator can be matched. The

total cost of turbine, transmitter and generator shall also be taken into consideration. For

micro-hydropower plant, 4 – 8 poles are selected to save the cost


- 6-19 -

6.4 Power Transmission Facility (Speed Increaser)

There are two ways of coupling the turbine and generator. One is a direct coupling with

turbine shaft and generator shaft. The other is an indirect coupling by using power

transmission facility (speed increaser) between turbine shaft and generator shaft.

Rated turbine speed is fixed by the selected type of turbine and the original design

condition of net head and water flow (discharge) cannot be changed. On the other hand,

generator speed is to be selected from frequency as shown in the above table. Therefore,

if the speeds of both turbine and generator are completely the same, turbine and

generator can be coupled directly. However, such design of direct coupling is not always

applicable due to high cost of turbine and generator, especially in case of micro or small

hydropower plant. The power transmission facility (speed increaser) is usually adopted

in order to match the speed of turbine and generator and save on cost.

Two kinds of speed increaser adopted for coupling turbine and generator are as follows:

1. Gear box type: Turbine shaft and generator shaft is coupled with parallel shaft helical

gears in one box with anti-friction bearing according to the ratio of

speed between turbine and generator. The lifetime is long but the cost

is relatively high. (Efficiency: 97 – 95% subject to the type)

2. Belt type: Turbine shaft and generator shaft is coupled with pulleys (flywheels)

and belt according to the ratio of speed between turbine and generator.

The cost is relatively low but lifetime is short. (Efficiency: 98 – 95%

subject to the type of belt)

In case of micro hydro-power plant, V-belt or flat belt type coupling is adopted usually

to save the cost because gear type transmitter is very expensive.


- 6-20 -

6.5 Control Facility of Turbine and Generator

6.5.1 Speed Governor

The speed governor is adopted to keep the turbine speed constant because the speed

fluctuates if there are changes in load, water head and flow. The change of generator

rotational speed results in the fluctuation of frequency. The governor consists of speed

detector, controller and operation. There are two kinds of governor to control water flow

(discharge) through turbine by operation of guide vane or to control the balance of load

by interchanging of actual and dummy load as follows:

1. Mechanical type: To control water discharge always with automatic operation of guide

vane(s) according to actual load. There are following two types.

Pressure oil operating type of guide vane(s)

Motor operating type of guide vane(s)

2. Dummy load type: To control the balancing of both current of actual load and dummy

load by thyristor i.e. to keep the summation of both actual and

dummy load constant always for the same output and speed of

generator.

The speed detection is made by PG (Pulse Generator), PMG (Permanent Magnet

Generator) or generator frequency.

In case of the mechanical type, ancillary equipment such as servomotor of guide vane,

pressure pump, pressure tank, sump tank, piping etc. or electric motor operating guide

vane with control system, are required. This means the cost of the hydropower plant will

be higher with such ancillary equipment.

In case of motor operating type, power source, motor and operating mechanism are also

required. For a micro-hydropower plant, the dummy load type governor is cheaper and

recommended.

Dummy load type governor can be controlled by IGC (Induction Generator Controler)

or ELC (Electronic Load Controller), which was developed and fabricated in Indonesia

and supplied to more than 30 micro-hydropower plants. Two types of dummy load are

adopted with heater, the air cooled and water cooled. In Indonesia, air cooled method

are usually applied instead of water cooled type due to durability and simple


- 6-21 -

construction of heater.

The capacity of dummy load is calculated as follows:

Pd (kW) = Pg (kVA) x pf (decimal) x SF

Where Pd: Capacity of dummy load (Unity load: kW)

Pg: Rated output of generator (KVA)

pf: Rated power factor of generator (%, a decimal is used for

calculation)

SF: Safety factor according to cooling method (1.2 – 1.4 times of

generator output in kW) in order to avoid over-heat of the heater

according to climate

Note: Maximum output of turbine (kW) may be applied instead of “Pg

(kVA) x pf (decimal)” because maximum generator output is limited

by turbine output even if the generator with larger capacity is

adopted.

6.5.2 Exciter of Generator

In case of synchronous generator, an exciter is necessary for supplying field current to

generator and keeping the output voltage constant even if the load fluctuates.

Various kinds of exciter are available, but at present the following types of exciter are

usually adopted:

1. Brush type: Direct thyrister excitation method. DC current for field coil is

supplied through slip ring from thyrister with excitation

transformer.

2. Brush-less type: Basic circuit consists of an AC exciter directly coupled to main

generator, a rotary rectifier and separately provided thyrister

type automatic voltage regulator (AVR).

The typical wiring diagrams for both brush type and brush-less type are shown in Figure

6.5.1 and 6.5.2.


- 6-22 -

Figure 6.5.1 Wiring diagram of brush type exciter

Figure 6.5.2 Wiring diagram of brush-less type exciter

For micro hydro-power plant the brush-less type is recommended due to easy

maintenance.

G

PT

CT

Ex. Tr

AVRPulse

Generator

Slip ring

(Speed Detector)

G

PT

CT

Ex. Tr

AVR

DC100V

Pulse

Generator

Rotating section

ACEx

(Speed Detector)


- 6-23 -

6.5.3 Single Line Diagram

The typical single diagram for both plants with 380/220V and 20kV distribution line are

shown in the following figures:

Figure 6.5.3 Single Line diagram of Power Plant with Low Tension Distribution Line

Figure 6.5.4 Single Line diagram of Power Plant with 20kV Distribution Line

V

Hz

H

A x3

ELC (with Hz Relay)

G

Turbine

Transmitter

if required

Dummy Load

MagnetContactor

x3

NFB

Generator

Vx3

Fuse

To Custmer

Lamp

Indicator

V

Hz

H

A x3

ELC (with Hz Relay)

G

Turbine

Transmitter

if required

Dummy Load

MagnetContactor

x3

NFB

Generator

Vx3

Fuse

Lamp

Indicator

M. Transformer

380V/20kV

Circuit

Breaker

or Fuse

Switch

Disconnection

Switch


- 6-24 -

6.6 Control, Instrumentation and Protection of Plant

The general evaluation of the potential sites selected through the above-described study

is then examined considering the methods described below to assess their suitability for

hydropower development.

6.6.1 Control Methods of Plant

There are many control methods for hydropower plant, such as supervisory control,

operation control and output control

1. Supervisory control method is classified into continuous supervisory, remote

continuous control and occasional control.

2. Operational control method is classified into manual control, one-man control and

full automatic control.

3. Output control method is classified into output by single governor for independent

network and water level control, discharge control and program control for

parallel operation with other power source.

In case of an isolated micro-hydropower plant for rural electrification, the occasional

control, manual control and governor control with dummy load is usually adopted

because no person can monitor the plant in full time basis and also to save on the cost of

control equipment. This means that the operator can visit the plant occasionally to start

and stop its operation if it is equipped with governor control and when some trouble

occurs, the operator could conveniently inspect the plant to take some necessary

measure.

6.6.2 Instrumentation of Plant

Though many instruments are required in the monitoring of hydropower plant during

operation, the following instruments may be furnished as the minimum requirement for

micro-hydropower plant in rural electrification.

1. Pressure gage for penstock

2. Voltmeter with change-over switch for output voltage

3. Voltmeter with change-over switch for output of dummy load (ballast)


- 6-25 -

4. Ammeter with change-over switch for ampere of generator output

5. Frequency meter for rotational speed of generator

6. Hour meter for operation time

7. KWH (kW hour) meter and KVH(Kvar hour) meter, which is recommended in

order to check and summarize total energy produced by the power plant if there is

some allowance in budget

6.6.3 Protection of Plant and 380/220V Distribution Line

Considering the same reason for cost saving in instrumentation, the following protection

is required as minimum protection for micro-hydro power plant in rural electrification.

1. Over speed of turbine and generator ( detected by frequency)

2. Under voltage

3. Over voltage

4. Over current by NFB (No Fuse Breaker) or MCCB(Molded Case Circuit Breaker)

for low tension circuit.

When items 1, 2 and 3 are detected by IGC or ELC (with adjustable by screw), MC

(Magnet Contactor) is activated and trips the main circuit of generator

6.6.4 Protection of 20kV Distribution Line

Normal protection system of line (Pole-mounted type Lighting Arresters and Fuses or

Fuse Switches) is to be provided throughout the line. However, the following two kinds

of system could be installed as protection of 20kV outgoing facility at power station.

1. The following facilities are to be installed at 20kV switchgear of power station in

case 20kV switchgear for large capacity and long outgoing line is required.

1) 1 no. 24kV Circuit Breaker, driven by AC operated closing and tripping

system of capacitor trip power supply device (3-phase, 200A for MHP )

2) 3 nos. 24kV Fuse Switches with fuse, hand operated type (3-phase)

3) 1 no. 24kV Earthing Switch, hand operated type (3-phase gang operated)

4) 3 nos. 20kV Lightning Arrester (more than 27kV, 5kA)

5) 1 no. 20 kV Voltage Transformer(3 phase, 22kV/110V )


- 6-26 -

6) 3 nos. 20kV Current Transformer (1-phase, Ratio to be fixed by the actual

capacity of MHP)

7) 1 set 20kV Busbars system

8) 1 no. Control and Protection Panel

In case 20kV cubicle is applied all the above facilities are to be installed in the

cubicle.

2. The following facilities only are to be installed by connection from 20kV terminal

of 20kV/380V transformer on the terminal pole at Power Plant, in case only

20kV/380V transformer is installed for step-up purpose due to small capacity

distribution line. In this case, protection panel for 20kV line is not required.

1) 3 nos. 24kV Fuse Switches with fuse, hand operated type (3-phase)

2) 3 nos. 20kV Lightning Arrester (more than 27kV, 5kA)

3) 1 lot 20kV line connection materials (Insulators, support structure, wires)

6.7 Inlet valve

Referring of water quantity and head of plant, suitable inlet valve is applied between

penstock and turbine for tight stopping of water supply for safety and maintenance.

However, it may sometimes be omitted for purpose of cost saving in case of low head

power plant if the stop log or gate at forebay can almost stop the water leakage from

forebay into penstock or separate discharge pass-way is provided at forebay

The inlet valve for micro and small power plant is classified into three(3) kinds as

follows:

Type Applicable head Applicable diameter Head loss Leakage

1.Butterfly valve; Not exceeding 200m Medium(up to 2.5m) Medium Medium

2.Bi-plane valve; Not exceeding 350m More than 500mmm Little Medium

3.Sluice valve; Exceeding 200m Small Almost zero Very less

More details are shown in Table 6.7.1.

For micro or small power plant, butterfly valve is adopted due to simple construction

and low cost.


- 6-27 -

Manual for Micro-Hydro Power Development Chapter 6 (ANNEX)

- 6-28 -

ANNEX.

Annex. 6.1 Brief Design of Cross Flow Turbine (SKAT T-12, 13 &14)

1. Cross Flow Turbine

At present Cross Flow turbine is the preferred turbine for micro power plant,. SKAT T-12, T-13 and

T-14 are recommended for micro-hydro power generation. The major advantages are as follows:

• Available technical data for design.

• Proper design with a wide range of heads and flows according to available actual site condition.

• Comparably low cost

• Easy installation

• Local fabrication, maintenance and repair

2. Fundamental Design Data

The following fundamental data shall be taken from the civil design.

1. Elevation of water level at forebay _______ m

2. Elevation of turbine center _______ m

3. Elevation of tailrace water if required _______ m

4. Rated flow (discharge) _______ m3/s

5. Internal diameter of penstock _______ cm

6. Length of penstock _______ m

7. Condition of nos. of bends of penstock, etc.

3. Application Limits

The applicable limit of Cross Flow turbine (T-12, T-13 & 14) can be summarized in following Table

6.A1.1.

Table 6.A1.1 Limit of Cross Flow Turbine (at turbine shaft)

Unit Lower limit Upper limit

Hnet Net head m 4 50

Q Discharge (Flow) l/s 100 820

P Shaft power output kW 10 250

bo Inlet width mm 100 1120

Number of intermediate discs - 0 8

Note: These limits must be respected. Engineering consideration such as practicability, relative cost,

tightness of inlet valve in closed position, opening force on inlet valve, strength of the rotor

blades, strength of the connection of the side discs to the rotor shaft, diameter of the shaft etc

demand the respect of these limits


- 6-29 -

On Chart 1 curves are shown for various outputs P. The corresponding formula is :

netHQP 8.9

The approximate rotational speed n of turbine can be read from the vertical scale on the right side of Chart

1. Its exact value is calculated with following formula for T-12, 13 & 14:

netHn 133

Example within the limits:

For a net head Hnet =30.89 m and a discharge Q=497 l/s, the following values can be determined on the

T-13 and T-14 application Fig. 6.A1.1.

The point of intersection of the Hnet and Q values is within the range of the white field, which means

that the T-13 and T-14 design is appropiate.

The shaft power output is just above 100 kW.

The rotational speed n is about 740 min-1.

Example outside the limits

Hnet = 6m and Q = 200 l/s

Although both Hnet and Q are within the limits, the intersection point on Fig. 6.A1.1 lies outside the

white, non-dotted field. For this application T-12, T-13 and T-14 cannot be used.

Please refer to Fig. 6.A1.1 in next page


- 6-30 -

Fig. 6.A1.1 Application Limits of The T-12, T-13 & T-14

/APPLICATION LIMITS OF THE T-12, T-13 & 14 CROSS FLOW TURBINE DESIGN, POWER OUTPUT, RPM AND d-d LINE

4. Using Power Transmission Facility

One of the advantages of Cross Flow turbine is that a power transmission facility with a belt drive

(Speed increaser) is easily applied in order to match both the speed of turbine and generator. The

advantages of using power transmission arrangement are summarized below.

• Application of most suitable design of turbine itself to match the various actual site condition

Easy and wide selection of turbine speed with proper speed increaser to generator

• Easier installation – horizontal shaft, common base for generator and turbine.

• Lower cost – to apply the small size generator with high speed, such as 1500 or 1000 rpm

5. Suitable Range of Site Heads and Flows for T-12, T-13 & 14

The Figure 6.A1.1 shows the applicable range of heads and discharges (flows) of Cross Flow turbine

to be used. The applicable range of Cross Flow turbines (T-12, T-13 and T-14) is shown with white

area in the figure and d-d line in the figure shows the limitation of strength of shaft for belt pulley as

follows:


- 6-31 -

(1) Intersection point below d-d line

Any transmission system between turbine and generator is permissible

(2) Intersection point above d-d line

Additional bending stress on the rotor shaft due to force created by e.g. belt tension is not

permissible, therefore, no belt pulley on the rotor shaft is allowed. In case of a belt transmission,

a separately supported pulley shaft would have to be coupled to the rotor shaft.

The range of Cross Flow turbine can be extended by using either a four-pole (1500 rpm) or a six-pole

(1000 rpm) generator.

6. Calculation of turbine design

The formulae for the calculation of the turbine performance values in design are as follows;

Formula (1): Inlet width

netH

Q

Dqb

max110

1 0b Inlet width m

netH Net head m

Q Discharge (flow) sm /3

max11q Unit discharge (flow) =0.67 for T-12

=0.76 for T-13

=0.80 for T-14

D Rotor diameter =0.3 m for T-12, T-13 & T-14 m

netH

Qb 623.30 for T-12

netH

Qb 39.40 for T-13

netH

Qb 9.40 for T-14

Formula (2): Shaft power output

netHQP 98.0 P Power kW

Turbine efficiency : 0.65 for T-12

0.76 for T-13

0.80 for T-14

Q＆ netH : Same as formula (1)


- 6-32 -

Formula (3) Turbine speed (rpm)

netHD

nn 11 n : Rotational speed rpm

11n : Unit speed = 39 (for T-12) rpm

= 40 (for T-13)

= 38 (for T-14)

D: Runner diameter= 0.3 m

The calculation result are shown in the following Table 6.A1.1 “ Calculation of Turbine Type

Crossflow T-14, T-13 & T-12 ”

Table 6.A1.1 Calculation of Turbine type Crossflow T-14, T-13 & T-12

It is noted that the optimum values are applied for the rated output, discharge and speed, etc. and maximum

values are not used as shown in above table.

Geodedic head Hgeo = 9.5 m

Net head /design head Hnet = 8.5 m

Design discharge Qt = 530 l/s

Diameter of runner Dt = 0.30 m

Width of nozzle bno = mm

Net head /design head Hnet = 8.5 m Hnet = 8.5 m Hnet = 8.5 m

Design discharge Qt = 530 l/s Qt = 530 l/s Qt = 530 l/sDiameter of runner Dt = 0.3 m Dt = 0.3 m Dt = 0.3 mUnit speed (opt) n11 = 38 rpm n11 = 40 rpm n11 = 39 rpmUnit flow (opt) Q11opt = 0.80 m^3/s Q11opt = 0.76 m^3/s Q11opt = 0.67 m^3/sEfficiency of turbine etat opt = 74.0% - etat opt = 70.0% - etat opt = 65.0% -Unit flow (max) Q11 max = 0.94 m^3/s Q11 max = 0.82 m^3/s Q11 max = 0.72 m^3/sEfficiency of turbine etat max = 73% - etat max = 68% - etat max = 63% -

Width of runner b0 = 757 mm b0 = 797 mm b0 = 904 mmShaft power output Pt opt = 32.7 kW Pt opt = 30.9 kW Pt opt = 28.7 kW

Pt max = 37.9 kW Pt max = 32.4 kW Pt max = 29.9 kWTurbine speed nt = 369 rpm nt = 389 rpm nt = 379 rpm

If turbine width is determined

Width of runner b0w = 760.0 mm b0w = 800.0 mm b0w = 900.0 mm

Discharge Qtw_opt = 531.8 l/s Qtw_opt = 531.8 l/s Qtw_opt = 527.4 l/sPower (turbine shaft) Ptw_opt = 32.8 kW Ptw_opt = 31.0 kW Ptw_opt = 28.6 kWTurbine speed ntw_opt = 369 rpm ntw_opt = 389 rpm ntw_opt = 379 rpmRun away speed ntw_max = 665 rpm ntw_max = 700 rpm ntw_max = 682 rpmGenerator/Transm. Effic. eta_g = 83% - eta_g = 83% - eta_g = 83% -El. Output Pel = 27.32 kW Pel = 25.84 kW Pel = 23.80 kW

Turbine T13Turbine T14 Turbine T12

Calculation of Turbine Size Type : Crossflow T14/T13/T12

Basic Data for Sample site


- 6-33 -

Annex. 6.2 Brief Design of Reverse Pump Turbine (PAT)

1. Reverse Pump Turbine (Pump as Turbine= PAT)

Standard pump units when operated in reverse as turbines have a number of advantages over

conventional turbines for micro-hydro power generation. Pumps are mass-produced, and as a result,

have advantage for micro-hydro compared with purpose-made turbines. The main advantages are as

follows:

• Integral pump and motor can be purchased for use as a turbine and generator set

• Available for a wide range of heads and flows

• Available in a large number of standard sizes

• Low cost

• Short delivery time

• Spare parts such as seals and bearings are easily available

• Easy installation – uses standard pipe fittings

There are several practical benefits of being able to use a direct drive pump as turbine (PAT), i.e. the

pump shaft is connected directly to the generator, as explained in the next section.

Pump suppliers usually stock a number of different pumps designed to be suitable for a wide range of

heads and flows. The actual range of heads and flows for which a PAT is suitable is explained in a

later section.

The simplicity of the PAT means that it does have certain limitation when compared with more

expensive types of turbine. The main limitation is that the range of flow rates over which a particular

unit can operate is much less than for a conventional turbine. Some ways of overcoming this

limitation are covered at the end of this chapter. Therefore , the selection of applicable pump should be

selected referring hereunder.

2. Using a Direct Drive Pumps as Turbine

One of the advantages of using a PAT instead of a conventional turbine is the opportunity to avoid a

belt drive. However, in some circumstances there are advantages to fitting a belt drive to a PAT.

The advantages of using a direct drive arrangement are summarized below.

• Very low friction loss in drive (saving up to 5% of output power.).

• Easier installation – PAT and generator come as one unit.

• Lower cost – no pulleys, smaller base plate.

• Lower cost (in the case of a ‘mono-bloc’ design) because of simpler construction, fewer bearings,

etc.

• Longer bearing life – no sideways forces on bearings.

• Less maintenance – no need to adjust belt tension or replace belts.


- 6-34 -

The use of combined pump-motor units is recommended for micro-hydro schemes that are to be used

only for the production of electricity, and where the simplest installation possible is required. There

are, however, some limitations to using such integral units, as listed below:

• Turbine speed is fixed to speed of generator –thus reducing the range of low rates when

matching the PAT performance to the site conditions.

• Limited choice of generators available for a particular PAT.

• No possibility of connecting mechanical loads directly to the PAT.

3. Suitable Range of Site Heads and Flows

Standard centrifugal pumps are manufactured in a large number of sizes, to cover a wide range of head

and flows. Given the right conditions, pumps as turbines can be used over the range normally covered

by multi-jet Pelton turbines, crossflow turbines and small Francis turbines. However, for high head,

low flow applications, a Pelton turbine is likely to be more efficient than a pump, and no more

expensive.

The chart in Fig. 6.A2.1 shows the range of heads and flows over which various turbines options may be

used. The range of Pelton and crossflow turbines shown is based on information from the range of

turbines manufactured in Nepal, and is compared with the range of standard centrifugal pumps running

with a four-pole (approx. 1500 rpm) generator. The range of PATs can be extended by using either a

two-pole (approx. 3000 rpm) or a six-pole (approx. 1000 rpm) generator, as shown in Fig 6.A2.2. This

range of pumps as turbines is based on standard centrifugal pumps produced by a major UK

manufacturer.

H(m)

Q(/s)

Key

Crossflow Turbine limit PAT limit @ 1550 rpm

500 400 300 200 150 100 70

50

40

30

20

10

5

2 4 6 8 10 15 20 30 40 60 80 100 150 200

CrossflowTurbines PAT

Fig. 6.A2.1 Head-flow Ranges for Various Turbine Option


- 6-35 -

Fig. 6.A2.2 Head-flow Ranges for Direct Drive Pumps as Turbines

The use of a pump as turbine has greatest advantage, in terms of cost and simplicity for sites where the

alternative would be either a crossflow turbine, running at relatively low flow, or a multi-jet Pelton

turbine. For these applications, shown by the hatched area on Fig. 6.A2.2, a crossflow turbine would

normally be very large compared with an equivalent PAT. Very small corssflow turbines are more

expensive to manufacture than larger ones because of the difficulty of fabricating the runner.

Therefore, a crossflow installation would require a large turbine running at slower speed than an

equivalent PAT, resulting in the need for a belt drive to power a standard generator. A Pelton turbine

for this application would require three or four jets, resulting in a complicated arrangement for the

casing and nozzles, although it would be more flexible than a PAT for running with a range of flow rates.

A small Francis turbine could also be used in this range, but would be even more expensive than

crossflow turbine.

What dictates the use of a pump as turbine is that it requires a fixed flow rate and is therefore suitable

for sites where there is a sufficient supply of water throughout the year. Long term water storage is not

generally an option for a micro-hydro scheme because of the high cost of constructing a reservoir.

Due to difficulty of site selection for PAT (Pump As Turbine), it is recommended that the client

should confirm its performance to the designer or pump manufacturer in advance, including the

characteristics of the pump and its induction motor to avoid that the characteristics of pump is

different by its manufacturer.

Table 6.A2.1 “Centrifugal Pump manufactured by Southern Cross for PAT” is attached hereunder

for reference only.

The engineer, who wants to know more detailed design, shall continue the study to the following

chapters hereunder.

H(m)

Q(/s)

70

50

40

30

20

10

5

2 4 6 8 10 15 20 30 40 60 100 200

4 pole limit (c. 1500 rpm)

500 400 300 200 100 70 50 40 30 20 10 5


- 6-36 -

Table 6.A2.1 Centrifugal Pump manufactured by Southern Cross for PAT

Pump Type

(rpm) (rpm) (l/sec) (m) (%) (l/sec) (m) (kW) 50 x 32 – 160-L 1400 1470 3.1 9.5 56 5.7 23.1 0.5 50 x 32 – 160-M 1400 1470 2.6 7.5 54 4.9 19.1 0.4 50 x 32 – 160-S 1400 1470 2.5 6.0 50 5.0 16.7 0.3 65 x 50 – 160-L 1400 1470 5.5 9.0 65 9.0 18.3 0.7 65 x 50 – 160-M 1400 1470 4.5 7.5 60 7.8 16.8 0.6 65 x 50 – 160-S 1400 1470 4.0 6.0 57 7.2 14.3 0.4 80 x 65 – 160-L 1420 1491 9.5 9.5 78 13.4 15.5 1.1 80 x 65 – 160-M 1420 1491 7.5 7.5 74 11.0 13.1 0.7 80 x 65 – 160-S 1420 1491 6.8 6.0 68 10 .6 11.6 0.6 80 x 50 – 200-L 1420 1491 10.0 15.5 72 15.0 27.9 2.1 80 x 50 – 200-M 1420 1491 9.0 12.0 69 14.0 22.7 1.5 80 x 50 – 200S 1420 1491 8.0 9.0 68 12.6 17.3 1.0 100 x 80 – 160-L 1420 1491 18.0 9.5 80 24.9 15.1 2.1 100 x 80 – 160-M 1420 1491 16.0 6.5 77 22.8 10.8 1.3 100 x 80 – 160-S 1420 1491 15.0 5.0 75 21.8 8.6 1.0 100 x 65 – 200-L 1420 1491 18.5 15.0 78 26.1 24.5 3.5 100 x 65 – 200-M 1420 1491 16.0 11.5 75 23.3 19.7 2.4 100 x 65 – 200-S 1420 1491 14.0 9.0 70 21.5 16.7 1.8 100 x 65 – 250-L 1450 1523 20.0 24.0 78 28.2 39.2 6.0 100 x 65 – 250-M 1450 1523 18.5 19.0 76 26.6 32.0 4.5 100 x 65 – 250-S 1450 1523 16.5 15.0 73 24.5 26.5 3.3 125 x 100 – 200-L 1440 1512 38.0 14.5 85 50.0 21.4 6.3 125 x 100 – 200-M 1440 1512 34.0 10.0 81 46.5 15.6 4.1 125 x 100 – 200-S 1440 1512 30.0 8.0 78 42.3 13.1 3.0 125 x 100 – 250-L 1450 1523 40.0 24.0 81 54.7 37.5 11.6 125 x 100 – 250-M 1450 1523 36.0 19.0 80 49.6 30.1 8.4 125 x 100 – 250-S 1450 1523 33.0 14.0 78 46.5 22.9 5.8 150 x 125 – 250-L 1460 1523 70.0 23.0 88 89.6 32.5 17.9 150 x 125 – 250-M 1460 1523 70.0 17.0 83 93.8 25.8 14.0 150 x 125 – 250-S 1460 1523 50.0 13.0 80 69.0 20.0 8.0

Flo

w a

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mp(

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Hea

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pum

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Eff

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as p

ump

Flo

w a

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Hea

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(Hn)

Pow

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Spe

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e


- 6-37 -

4. Overcoming the Limitation of Using a Pump as Turbine

A purpose-built water turbine is generally fitted with a variable guide vane (or vanes) or a spear valve,

which allows the machine to run efficiently with a wide range of flow rates. When a standard

centrifugal pump is used as a turbine, no such adjustment is possible. However, once installed, a pump

as turbine that is well matched to the site conditions will operate close to maximum efficiency.

If the flow rate falls a little below the required flow for maximum efficiency, power can still be

generated – but less power will be obtained. This is explained in more detail in Annex 6.1. Another

option for dealing with low flow rates is to use intermittent operation. By using a special intake and a

small storage tank it is possible for a PAT to run intermittently. The special intake consists of a siphon

arrangement.

If the flow rate increases, it is not possible to generate more power using only one pump. A second

pump could be installed but the additional cost of installing more than one unit may outweigh the

advantage of buying a pump instead of a conventional turbine. Annex 6.2 gives more details of

parallel operation of PATs.

When a direct drive electric pump is used, the turbine and generator must run at the same speed. This

can limit the range of flows over which the pump can run. Care must be taken to avoid overloading

(either electrical or mechanical) of the generator. The electrical output of an induction generator

should normally be limited to 80% of the rated power output as motor.

5. Understanding Pump as Pump Performance Curves

Before looking at your pump as a turbine, you need to understand it as a pump. The main tool for this

is the performance curve, which shows how the head and flow delivered by the pump are related. As the

flow delivered by the pump increases, the delivery head decreases. The head-flow curve of each pump

is often available form the pump manufacturer.

The other piece of information that you need to know for your pump is the point at which it works most

efficiently. This is called the best efficiency point. The pump efficiency, plotted against the flow rate,

is shown in Fig. 6.A2.3. The maximum value of efficiency varies according to the type and size of

pump, but is typically 40% to 80%. The best efficiency point (bep) occurs at a particular value of flow

rate.


- 6-38 -

ηp

ηmax

Qbep Qp

Fig. 6.A2.3 Pump Efficiency Curve

The efficiency values can be shown on the head-flew curve, as shown in Fig. 6.A2.4. Information

from pump manufacturers is sometimes shown in this way.

Hp

Hbep

Qbep Qp

50%

60%

70%65

%

65%

60%

50%

Fig. 6.A2.4 Pump Head and Flow with Efficiency Values Shown

If you have no efficiency data for the pump, but do have a curve showing input power against flow rate,

then it is possible to calculate the values at the best efficiency point. The relationship between head,

flow-rate input power and efficiency is given by the following equation:

Efficiency (η) =Pin

QH 81.9×100 (1)

where: H is head (m)

Q is flow rate (1/2)

Pin is mechanical input power (W)

9.81 is acceleration due to gravity (m/s2)

ηis pump efficiency as a percentage.


- 6-39 -

The steps for calculating the value of maximum efficiency are as follows:

1. Use the head-flow curve to obtain the head and flow rate at best efficiency point (bep).

2. Use this flow rate on the power input-flow curve to get Pin.

3. Put these values in equation (1) to obtain the efficiency.

Note that, especially for pumps with integral motors, the power curve may show electrical power

consumption rather than mechanical input power. In this case, use Appendix D to estimate the

efficiency of the motor. Then sue the following equation to calculate Pin.

Pin = Pelec ×100

(%)motor　 (2)

Where: Pin is mechanical input power (W)

Pelec is the electrical power consumption of the motor (W)

ηmotor is motor efficiency as a percentage.

Example 1: Finding pump best efficiency conditions.

The manufacturer of a 65-40-200 (2.5” × 1.5” × 8 pump gives the head-flow curve and electrical

power input curve as shown below in Fig. 6.A2.9a and 9b. The flow at best efficiency is 14m3/hr,

which can be converted to 3.89 l/s by dividing by 3.6, the conversion factor given in Appendix E.

The head at best efficiency is 11.8m

The motor is rated at 1.5 hp (1.1 kW), 1,450 rpm, for operation on a 3-phase, 50 Hz supply.

According to the table in Appendix D, this size of motor has a maximum efficiency of around 75%.

The value of electrical power consumed, for the best efficiency point, can be found from Fig. 6.A2.

9b. At a flow rate of 14m3/hr, the power is 1,050 W. This is Pelec. Using equation (2):

Pin = Pelec × 100

(%)motor= 1050 ×

100

75 = 788W

The pump best efficiency is therefore, from equation (1):

η= inP

QH 81.9 × 100 =

788

81.989.38.11 × 100 = 57%


- 6-40 -

Hp

(m)

Qp (m3/hr)

18

16

14

12

10

8

6

4

2

5 10 15 20

Pelec

(W)

Qp (m3/hr)

1000

750

500

250

5 10 15 20

(a) Head and flow, with best efficiency point (b) Electrical power consumption

Fig. 6.A2.5 Manufacturer’s Pump Curves

H

Q

Hsitehf

PAT Curve Site CurveOperatingPoint

Fig. 6.A2.6 Turbine Curve and Site Curve

The speed of the turbine will vary according to the load that is put on it, and there is a different

head-flow curve for each speed. Three such curves are shown in Fig. 6.A2.7. The middle curve,

labeled N=100% is for the normal operating speed (the same as in Fig. 6.A2.8). The curves labeled

N=130% and N=80% are for speeds 30% higher and 20% lower than normal operating speed. Note

that for each speed, the operating point it given by the intersection of the turbine curve with the site

curve.

If a load, which is higher than design load, is put on the turbine, the speed goes down. For the pump

shown in Fig. 6.A2.7, this causes a slight increase in flow rate, which is usually the case for

centrifugal pumps running as turbines. When the load on the turbine is reduced, the speed increases.

If there is no load, the speed of the turbine increases to a maximum, which is known as runaway.

The curve of maximum speeds is also shown on Fig. 6.A2.7 (labeled N=max). In the case illustrated,

the actual speed at runaway is (by extrapolation) approximately 140% of normal operating speed.


- 6-41 -

H

00 Q

Site CurveN=140%

N=130%

N=100%

N=80%

N=

max

Fig. 6.A2.7 Turbine Head and Flow at Different Speeds

6. Obtaining the Best Efficiency Point with Limited Data

If the best efficiency point is not known but you have a power curve, calculate the efficiency using

equation (1) as above, for a number of different low rates. By a trial and error method, obtain the

maximum efficiency. The head and flow corresponding to the maximum efficiency will define the best

efficiency point.

Sometimes, no curve is available that shows either input power or electrical power consumption. In

this case, some information may be obtained from the pump name plate. The data given on the pump

name plate may consist of a single value for head and for flow (which is not always the head and flow

for best efficiency pump operation) or a range of heads and flows. One approximation for the best

efficiency conditions can be made by using:

Qbep = 0.75 Qmax; Hbep = 0.75Hmax (3)

A useful check can be made on these estimates by an alternative method, which is based on physical

measurements of some parts of the pump.

7. Understanding Pump as Turbine Performance Curves

The performance curve for the turbine shows how the head is related to the flow through the turbine

(see Fig. 6.A2.8). For turbine operation, the flow increases with increasing head. The single curve

shown is for the normal operating speed, i.e. that determined during detailed design.

It is also possible to plot the curve showing the head and flow available at the site (see Fig. 6.A2.6).

This is the head available at the turbine and is equal to the vertical height between the intake from the

stream and the turbine outlet, less the frictional head loss in the penstock. The intersection of the

turbine performance curve and the site curve in Fig. 6.A2.6 gives the head and flow at which the turbine

will actually operate. This is known as the operating point.


- 6-42 -

H

Hｔ

Qt Q0

0

×Limit of PAT operation

Fig. 6.A2.8 Pump as Turbine Head and Flow


- 6-43 -

SELECTING PUMP AS TURINE FOR A PARTICULAR SITE

This chapter gives procedures for selecting a pump as turbine to match a particular site, using either

performance calculations of turbine testing.

Matching a Pump as Turbine to Site Conditions

In selecting your site, you choose a particular set of head and flow conditions. The flow rate is

normally determined by the minimum flow rate, i.e. the flow that is available throughout the year. The

head is determined by the vertical height between the intake from the stream and the turbine outlet, less the

head loss in the penstock for this particular flow rate. A pump needs to be selected for which the head and

flow, at the turbine best efficiency point, are as close as possible to the site conditions.

This section gives the calculations needed to get the turbine head and flow at best efficiency point for

a particular pump. The running conditions in terms of head and flow, for best efficiency as a turbine, are

very different from the rated pump output, although the PAT efficiency will be approximately the same as

for pump operation. Friction and leakage loses, within a centrifugal pump, result in a reduction of head

and flow from the theoretical maximum. The head and flow required, when running as a turbine, will be

greater than the theoretical values, in order to make up for the losses. The following equations are given

in the literature to predict turbine head and flow for constant speed:

Q1 = maxbepQ

; H1 = maxbepH

; η1 =ηmax (4)

where Qbep is the flow rate and pump best efficiency point (bep)

Hbep is the head at pump bep

ηmax is the pump maximum efficiency

and Q1 is the flow rate at turbine best efficiency point (bep)

H1 is the head at turbine bep

η1 Is the turbine maximum efficiency.

These equations imply that the ratios Q1/Qbep and H1/Hbep are equal, but experimental results show

that the head ratio is usually greater than the flow ratio between turbine and pump modes. The prediction

can be improved by using different powers ofηmax for the head and flow ratios, following a method

proposed by KR Sharma of Kirloskar Co., India. If the turbine speed is the same as the pump speed, these

equations are:

Q1 = 8.0

maxbepQ

; H1 = 2.1

maxbepH

; η1 = ηmax (5)

The following example shows how to calculate the head and flow needed by the turbine when the

turbine speed is the same as the pump speed.


- 6-44 -

Example 2: Calculation of turbine best efficiency point (at pump speed).

The manufacturer of a particular pump gives curves that show that as a pump is maximum efficiency

is 62% when delivering 20 l/s at a head of 16 in at 1,500 rpm. The pump is required for use as a

turbine, driving a synchronous generator at 1,500 rpm. The turbine performance at best efficiency

predicted from equations (5) will be:

Q1 = 8.0

maxbepQ

= 8.062.0

20 =

682.0

20= 29.3 l/s

H1 = 2.1

maxbepH

= 2.162.0

16 =

563.0

16 = 28.4 m

Often the turbine speed will not be the same as the rated pump speed and it is necessary to use

additional equations to take into account different running speeds of turbine and pump. Before

presenting the equation it is necessary to explain the ‘Affinity Laws’.

The Affinity Laws relate the head, flow and power of a pump or turbine to its speed:

Flow (Q) is proportional to speed (N)

Head (H) is proportional to N2

Power (P) is proportional to N3

These relationship can be use particularly for calculating the running conditions at best efficiency point.

The equations for head and flow are:

Q1 (at N = N1) = pN

N1 ×Q1 (at N = Np) (6)

H1 (at N = N1) = 21 )(pN

N×H1 (at N = Np) (7)

where Np is the related pump speed

N1 is the turbine running speed

Substituting these equations into equations (5) gives:

Q1 = pN

N1 × 8.0

maxbepQ

; H1 = 21 )(pN

N× 2.1

maxbepH

(8)

An example of carrying out this calculation is given on the next page. It must be stressed that,

although this methods is more accurate than the equations normally given in the literature (4) it is still

only approximate. The actual values of Qt and Ht may be as much as ±20% of the predicted value for

the dep. This may or may not have a significant effect on the PAT output, depending on the


- 6-45 -

performance characteristics. It is therefore recommended that, wherever possible, after initial selection,

the pump is tested as a turbine to find out what power will be produced at the available head and flow.

The method for testing is described in the next section.

Example 3: Calculation of turbine best efficiency point at 1550 rpm.

The head available at a particular site is 26m, and the flow is 7 l/s. It was suggested that the pump

assessed in Example 2 could be used as a turbine for this site.

The induction motor is to be used as a generator directly driven from the turbine. The turbine

speed is therefore fixed by the generator speed. From the pump speed of 1450 rpm, the turbine

speed is calculated to be 1550 rpm. Using the equations above (8), the predicted best efficiency

conditions for turbine operation are:

Q1 = pN

N1 × 8.0

maxbepQ

= 1450

1550 ×

8.057.0

89.3 = 6.52 l/s

H1 = 21 )(pN

N× 2.1

maxbepH

= 2)1450

1550( ×

2.157.0

8.11 = 26.5 m

These values of head and flow are close to the site conditions, and the pump is therefore suitable.

Due to some difficulty of selection of PAT (Pump As Turbine), it is recommended as sample for brief

selection to refer to the attached Table 6.A2.1 of “Centrifugal Pump manufactured by Southern Cross

for PAT” attached hereunder,.

The client is requested to ask the designer the details of design with technical explanation for the

selected pump for PAT, with reference to the characteristics of the actual pump since each turbine is

made by different manufacturer.


- 6-46 -

Annex. 6.3

Technical Application Sheet of Tender

for Electro-mechanical Equipment

1. Purchaser ______________________________________________________

2. Name of Plant ______________________________________________________

3. Location ______________________________________________________

4. Fundamental matters

1) Elevation of water level at forebay basin _______ m

2) Elevation of Turbine center _______ m

3) Rated water flow (Dischrge) _______ m3/s

4) Internal diameter of penstock _______ cm

5) Length of penstock _______ m

6) Number of house holders _______ HH

7) Proposed area of house holdesr

______________________________________________________________

8)

5. Electro-mechanical Works

1) Generating Equipment

(a) Hydraulic turbine and auxiliary equipment

- One ＿＿＿kW cross flow type turbine with common base for generator (Note: Output shall be designed by the Tenderer referring to final output at generator terminal ＿＿＿kW.)

- One inlet valve (diameter: _______ cm)

- One water level gauging

- Maintenance tools and spare parts

(b) Power transmitter between turbine and generator (If required)

- One Mechanical power transmitter (gear or belt) with pulleies.

(b) Generator and Control Equipment

- One ＿＿＿kVA horizontal shaft drip-proof type synchronous generator with AVR (or Induction generator)

- One generator control system of ELC (or IGC) including protective relays, meters, surge absorber, space heater and control accessories

- One dummy load (air-cooling) complete with accessories

One Control panel with meters, switches, lamps, MC & MCB, etc.

- One set of spare parts for operation and maintenance


- 6-47 -

6. 20kV Distribution Facilities (If required)

1) Distribution Line

(a) 20kV Switchgears for outgoing line with Circuit breakers, PT, CT, Lightning

arresters and other necessary accessories. (If required)

(b) 20kV/380V step-up and step-down Transformers

(c) 20kVoverhead lines with steel or wooden poles (7m) with accessories , insulated wires of single core (70, 35,16sq.mm), Insulators, Lightning arresters and all necessary accessories according to the Tenderer’s design, of which voltage drop calculation shall be attached the Tender.

(d) Two-cores aerial bundled conductor (ABC) cables for connection to

householder, watt-hour meters and

(e) Molded circuit-breakers (MCBs) with weather proof box for protection of house

connections (one each for 5 or 6 householders) to be mounted on pole.

7. 380/220 Distribution Facilities including connection and in-house wiring for house holders

1) Distribution Line

(a) 380/220V overhead lines with steel or wooden poles (7m) with accessories , twisted cables of four or two cores (70, 35,16sq.mm) and all necessary accessories according to the Tenderer’s design, of which voltage drop calculation shall be attached the Tender.

(b) Two-cores aerial bundled conductor (ABC) cables for connection to

householder, watt-hour meters and

(c) Molded circuit-breakers (MCBs) with weather proof box for protection of house

connections (one each for 5 or 6 householders) to be mounted on pole.

2) Other Materials to be supplied to house holder

(a) Supply and connection of the in-house connection materials and handing over

of the remaining materials for the distribution line construction.

8. Training of O&M Staff

1) During the installation works of the Plant, the Contractor shall be required to provide the plant operators with on-the-job training by engaging them in the works.

2) After the Plant is in operation, the Contractor shall be required to furnish the qualified engineers to repair the part and instruct plant operators, if requested due to any trouble of the Plant during Defect Liability Period.


- 6-48 -

The Contractor is requested to fill the following Table with proposed facilities and remarks

MECHANICAL & ELECTRICAL

No Description Unit Q’ty Manufacturer Remark

1 Inlet valve (Butterfly type) 2 Crossflow Turbine a Turbine b Turbine base frame c 3 Electronic Load Controller a b 4 Dummy Load ( a. Air Cooling Heater nos. b. Housing of Ballast unit c. 4 Generator a. Synchronous Generator Stamford unit b. Generator base frame unit c. d. 5 Accessories, Spare parts & Tools unit a b c d e f 6 Set up & Installation ls 7 Transportation & Packaging ls 8 Testing and Trial run ls 9 Commissioning Test ls


- 6-49 -

Annex. 6.4 Brief Design for Electro-mechanical Equipment of Micro Hydro Power Plant

1. General

Various components of power plant equipment (valve, turbines, controller and generators etc.) are

explained in this “Manual”. Micro hydro power plants for rural electrification should follow the

said approach due to the reason of reliable design data, available manufacturing abilities including

distribution line design considerations, etc. Considering difficult availability of well-trained

operator in rural area and spare parts for future maintenance, all facilities except for small parts

shall be locally manufactured or included in the order as mandatory spare parts.

It is, therefore, recommended to adopt the following Electro-mechanical equipment and facilities

for rural electrification in an isolated grid.

2. Generating Facility

The applicable main machines (turbine and generator) for micro hydro power plant for rural

electrification referring to the present technology and manufacturing capability.

2.1 Turbine

Turbine type : Net head Flow(discharge) Turbine output Generator output:

Cross Flow 4 – 30 m 0.2 – 0.7 m3/s 8 – 85 kW 10 – 75kVA

Reverse pump (PAT) 4 – 20 m 0.04 – 0.13 m3/s 2 – 5 kW 2.5 – 6.5kVA

The final output of generator is the product of Hnet, Q, t, m, & g according to site condition,

however, the turbines outside of above each range, can be applied if the results of calculation is

within acceptable range shown in this “Manual”. Therefore the output shall be calculated in detail

and finally checked referring to this “ Manual”.

In case of reverse pump turbine, the turbine is selected from a pump directly coupled to induction

motor with almost same head and discharge as design condition at site, considering efficiency apex

of the said pump.

Generator

Generator type: Frequency Rotation speed Power factor Required output

Synchronous 50Hz 1500 rpm 0.8 (80%) > kVA (=kW/0.8)*

Induction 50Hz 1500 rpm 0.8 (80%) >kVA(=kW/0.8)**

Note: * In case of synchronous generator, the generator shall be selected from the one with available standard

output (kVA) more than the calculated kW of turbine (turbine output/0.8) with AVR in market.

** In case of induction generator, the induction motor is used an induction generator with additional

capacitors. The one directly coupled with the pump shall be selected as generator because the

separate selection of generator is somewhat difficult due to best efficiency point of turbine.


- 6-50 -

Table of Brief Selection of Turbine and Generator for MHPP

Euipment Type Applicable range for Indonesian manufacturer

Remarks

1-1 Turbine Cross Flow Water energy(Pw): 8 – 85kW Headnet(Hn): 4 – 30 m Discharge: 200 – 700 l/s Turbine efficiency t: 0.7 Pw= 0.98 x Pw x Hn P= Pw x t Turbine output(P): 5 – 60kW

SKAT T-12, T-13 or T-14 ELC control

1-2 Turbine Reverse pump Water energy(Pw): 3 – 8kW Headnet(Hn) 4 – 20 m Discharge: 40 – 130 l/s Turbine efficiency t: variable to bep of pump & required output of turbine bpf: Best Efficiency Point Pw= 0.98 x Pw x Hn Pt= Pw x t

Turbine output(Pt): 2 – 5kW

Available pump referring to bep (best efficiency point of induction motor) IGC control

2-1 Generator Synchronous Output(Pg) : Available standard output P (kVA)> (Pt x m x g ) / 0.8 Rotation speed: 1500 rpm Frequency: Constant (50Hz) Voltage: Constant by AVR Efficiency: High Power transmitter is usually required

With ELC AVR is furnished on generator itself

2-2 Generator Induction motor Output(Pg): Available standard output P (kVA)> (Pt x m x g ) / 0.8 or standard output of motor for the pump Capacitor: to be added for excitation Rotation speed: 1500 or 1000rpm Frequency: Constant (51-51.5Hz) but not so stable due to load Voltage: Variable without AVR Efficiency: Variable by load Direct coupling is usually applied

With IGC

2.2 Inlet valve

Butterfly valve is recommended to be installed just in front of turbine for safety operation and

maintenance. The diameter shall be not less than diameter of penstock to save head loss.

2.3 Power transmitter facility ( Speed increaser)

In case the rotation speed of turbine and generator are not matched, a power transmitter of belt type

shall be provided .


- 6-51 -

2.4 Governor with Dummy Load (Ballast)

For micro hydro power plant, dummy load (ballast) type governor shall be selected as load

controller, ELC (for synchronous generator) or IGC (Induction generator) because of easy

maintenance due to electronic type and low cost. In case of air cooling type dummy load, well

ventilated system shall be considered for design of powerhouse.

2.5 Panel for Control, Instrumentation and Protection

Panel for controller (governor), instrumentation, protection and low tension (LT) switchgears shal

be provided for easy operation, monitoring and maintenance.

2.6 380/220V Distribution Line

In case the calculated voltage drop at farthest consumer area by 380/220V line is within 5 %, the

outgoing circuit shall be connected to the LT distribution line.

2.7 20kV Distribution Line

In case the calculated voltage drop at farthest consumer area by 380/220V line is over 5 %, the

outgoing circuit is to be stepped up to 20kV by transformer(s) and connected to 20kV distribution

line through 20kV switchgear. In this case step down transformer is also required near consumer

area.

3. Brief Design Procedure

The approach of brief design shall be made as follows;

1) At first, the suitable location for power plant shall be selected in that area referring the required

power consumption (for example; Total kW =(150W x Number of house holder + Public

use)/1000).

2) According to the survey results of suitable sites, the available data of gross head(m), net

head(m), water flow(l/s) through years and proposed output shall be fixed as civil data.

3) According to the above data in 2), the suitable turbine and generator shall be selected referring

to the above table

4) The necessity of power transmitter shall be checked if the rotation speed of both the turbine

and generator are not same. Usually the belt (V-belt or flat belt) type with proper diameter

pulleys on both turbine and generator is applied for micro hydro power plant

5) The capacity of dummy load (ballast) controlled by ELC or IGC shall be calculated by

following formula.

For 3-phase network: Dummy load (kW) = Generator output (kW) x safety factor (1.2 ~ 1.4)

For single phase network: D. load (kW) = Generator output (kW) x safety factor (1.2 ~ 1.4)

Note: Safety factor is 1.2 for well-ventilated room for air cooling. If not, SF should be

increased to 1.3 or 1.4 according to the cooling condition.


- 6-52 -

6) The controller of synchronous generator with turbine should be ELC and that for induction

generator should be IGC, which are so far well designed panel including speed control,

instrumentation and protection system as minimum requirement for micro hydro power plant

(MHPP). Therefore, the panel with ELC (for synchronous generator) or IGC (Induction

generator) can be applied without any additional facility for L/T (low tension: 380/220V)

power supply system.

7) For distribution line, at first the voltage drop at farthest house-holder area by L/T line shall be

calculated referring “Manual”. The L/T line can be applied if the voltage drop is within 5 %.

8) If the voltage drop by L/T line becomes more than 5 %, 20kV distribution line shall be applied

for the power supply with step-up and step-down transformers and some protection facilities of

20kV lines, such as fuses, fuse switches, lightning arresters etc. Some switchgears may be

required for large capacity and long line..

9) For distribution line, it is recommended to furnish a weather proof box with single phase MCB

per each 5 – 6 house-holders on line pole for easy future maintenance.

10) For each house, 3 nos. of lamps and 1 no. of outlet respectively with switch shall be wired with

insulated cables as in-house wiring.

4. Recommendation of Main Equipment

The brief design of MHPP is shown and explained in the above chapter for the Client’s

(Purchaser’s or Employer’s) basic design purpose.

It is, however, recommended to take the following careful attention before purchasing the power

plant.

1) Water turbine

Cross Flow turbine shall have enough design data certified by complete model test results,

which shall be attached for evidence to show that the design of turbine is guaranteed for its

performance. The Cross Flow turbine without such evidence should not be accepted.

Reverse pump turbine (PAT) shall be selected the set of pump with induction motor for nearly

same head and discharge. Otherwise, it is difficult to choose the combination of pump and

generator (induction motor) due to somewhat complication of best efficiency point. The reverse

pump turbine is not recommended for the one with variable head and especially discharge.

2) Generator

Synchronous generator shall be selected the one of blush-less type, star winding with AVR

in its housing for high quality and stable electricity and easy maintenance in future.

Induction generator shall be selected from the set of the induction motor of delta winding as set

of pump with nearly same head and discharge.


- 6-53 -

3) Detailed Design

It is strongly recommended to mention the following sentence clearly in Tender document

and/or Contract document for Client’s clarification, safety operation and future maintenance.

“The Contractor shall conduct all of the detailed design, which include all necessary analyses

with preparation of construction drawings, installation drawings, and others deemed to be

required. The Contractor shall fully be responsible and accountable for the detailed design in its

quality, reliability and safety. Whenever the Client so desires, the Contractor shall be provided

enough explanation to his detailed design.”


- 7-1 -

Chapter 7 DESIGN FOR DISTRIBUTION FACILITIES

7.1 Concept of Electricity

Electric is similar to Water.

Hydropower potential is proportional to the product of Height (m) of falling water and

the Volume of flowing water (m3/s).

Similary, Electric power potential is proportional to Voltage (V) and Ampere.

E (V)

I (A)

P (W) = E (V) * I (A)

H (m) Q (m3/s)

Turbine P (W) = 9.8* Q(m3/s) * H (m)

T


- 7-2 -

Thicker is easier to flow.

Thicker is easier to flow, because thicker is less resistance.

Note:

When designing a distribution line in detail, it is recommended to consult licensed

Electrical Engineer.

< Q (m3/s) Q (m3/s)

Pipe

I (A) I (A)

Conductor

<


- 7-3 -

7.2 Selection of Distribution Line Route

Locations of supporting structures should be selected at places where:

(a) Easy to access and maintenance

(b) Soil condition is firm and stable

(c) No problem in land acquisition

(d) No adverse effect on buildings, trees, etc

(e) Distribution route should be shortest

(f) If poles are set around steep slope or at the bottom of a cliff, take into account the

following, as illustrated:

Because landslide may take place,

consider the safer route.

Avoid standing a pole at the bottom of

the cliff.

(f) A height of conductor from ground should be more than 4 m.

Low voltage: more than 4 m

20kW: more than 6.5 m


- 7-4 -

Allowable height






- 7-5 -

7.3 Distribution Facilities

Supporting structures are included such as follows:

(a) Pole (d) Protection

(b) Guy wire (e) Distribution transformer

(c) Conductors and cables (f) House connection


- 7-6 -

7.4 Pole

Standard poles for overhead lines are classified as shown in Table 7.4.1:

Priority of use shall be on locally manufactured concrete poles. For concrete poles,

manufacture of longer and stronger poles will be preferred to widen scope of use. To

improve workability in construction and maintenance, the pole design to enable fixing

of step bolts.

Table 7.4.1 Application of Supporting Structures Supporting structures Application Concrete poles Generally applied Wooden poles (including Bamboo poles)

Applied to areas where access of heavy machines is difficult

Steel poles Applied to areas where access of heavy machines is difficult (standard is attached to Ref. 7-1)

Concrete pole Wooden pole Steel pole

7.4.1 Span Length of Poles

The length of the span between distribution line supports is to be determined taking into

account the following:

Recommended Span is 50 m;

Maximum 80 m, for areas outside settlements, areas for rice fields, and open spaces;

Maximum 50 m, for areas within the population settlement.


- 7-7 -

7.4.2 Allowable Minimum Clearance of Conductors and Environment

The minimum clearances of conductors above ground will be designed with the

following criteria: Conductor height above

ground 20 kV Low Voltage

Road crossing 6.5 m 4.0 m Along road 6.0 m 4.0 m

Other places 6.0 m 4.0 m

Vertical clearance between 20 kV bare conductor and LV insulated

conductor 0.8 m

Clearance between phases of 20 kV bare conductors 0.8 m

Vertical clearance between 20kV bare conductors 1.0 m

Clearance between LV insulated conductors 0.2 m

7.4.3 Height of Poles

The height of pole is to be determined taking into account the following factors:

(a) Necessary height of the feeder conductors above the ground can be secured under

the largest sag.

(b) Necessary clearance between the feeder conductors and buildings, other electrical

wires or trees can be secured (clearance under maximum sag should be examined).

The recommended height of the supporting structures is as follows:

Table 7.4.2 Recommended height of Supporting Structures Voltage Recommended Support Length 20 kV 9 m

Low Voltage 7 m

(a) The recommended minimum pole setting depth is one sixth of pole length. For

example:

Pole setting depth = Pole length 9m×1/6 = 1.5 m

(b) If soil condition is not stable, the root of pole should be reinforced firmly. Refer to

following pictures:


- 7-8 -

7.4.4 Size of Poles

Size of pole is to be determined taking into account the moment on pole by wind load.

The following table shows the relation between size and height of poles each cable size

in case of square shape.

Concrete: 210 kgf/cm2

Reinforcement: SR235, allowable stress is 1400 kgf/cm2, 19 mm2

D0 = size of square on side of pole

Pole span: 50 m cable size:70mm2

length

of pole

height

of pole

maximum

moment by

pole

maximum

moment by

cable

sum of

moment

D0

(cm)

reinforcement

19mm2（pcs） d (cm)

7 m 5.8 m 204 898 1103 20 8 4 for LV

9 m 7.5 m 388 1155 1543 23 8 4 for 20kV

cable size:35mm2

length

of pole

height

of pole

maximum

moment by

pole

maximum

moment by

cable

sum of

moment

D0 reinforcement


7 m 5.8 m 184 583 767 18 8 4 for LV

9 m 7.5 m 338 750 1088 20 8 4 for 20kV

cable size: 16mm2

length

of pole

height

of pole

maximum

moment by

pole

maximum

moment by

cable

sum of

moment

D0 reinforcement


7 m 5.8 m 174 519 693 17 8 4 for LV

9 m 7.5 m 338 668 1005 20 8 4 for 20kV

D0

reinforcement

d


- 7-9 -

7.5 Guy wire

Guy wire should be installed to balance the pole. Kinds of load to supporting structures

are (a) vertical load, (b) longitudinal load, and (c) lateral load.

(a) Vertical load

Pole weight, cable weight, vertical load of wire tension load, etc.

(b) Longitudinal load

Wind pressure to pole, imbalanced load from difference of span length

(c) Lateral load

Wind pressure to cable, component of lateral load of wire tension, etc.

The place where guy wire should be constructed is as follows:

-End of distribution line

-Distribution lines bend like an elbow-shaped. It is possible to omit guy wire if the

angle is less than 5 degrees.

-To reinforce straight distribution line against wind pressure

Tension

(a)

(c)

(b)

wind pressure

wind pressure


- 7-10 -

- In undulated area, guy wire shall be installed, if necessary.

Use of stay wire for 20 kV pole 9 m – 200 daN (Underbuild)

(Guy wire angle with surface = 60 degree) Bend Angle

Conductor size 10 < β < 45 45 < β < 75 75 < β < 90

AAAC – 25 m m2 AAAC – 35 m m2 AAAC – 50 m m2 AAAC – 70 mm2

Type I Type I Type I Type I

Type I Type I Type II Type II

Type I Type II Type II Type II

Use of stay wire for 20 kV pole 9 m – 200 daN (Semi-Underbuild)


Conductor size 5 < β < 10 10 < β < 30 30 < β < 60 60 < β < 75 75 < β < 90

AAAC – 25 mm2 AAAC – 35 mm2 AAAC – 50 mm2 AAAC – 70 mm2


Type I Type II Type II Type II

Type II Type II Type II Type III

Type II Type II Type III Type III

Type II Type III Type III Type III

Use of stay wire for 20 kV pole 7 m – 100 daN


Conductor size 5 < β < 10 10 < β < 60 60 < β < 90

2 x 25 + 1 x 25 mm2 3 x 25 + 1 x 25 mm2 2 x 35 + 1 x 25 mm2 3 x 35 + 1 x 25 mm2 2 x 50 + 1 x 35 mm2 3 x 50 + 1 x 35 mm2 2 x 70 + 1 x 50 mm2 3 x 70 + 1 x 50 mm2

- - - -


Type I Type I Type I Type I Type I Type I Type I Type I

Type I Type I Type I Type I Type I Type I Type II Type II

Type I : Guy wire diameter = 5 mm

Type II : Guy wire diameter = 9 mm

Type III : Guy wire diameter = 2 x 9 mm


- 7-11 -

H = Depth of buried part of stay rod

h = Length of remaining stay rod

above stay rod

α= Angle between stay and surface

(horizontal)

Use of stay rod, stay block and depth of burial for each stay - classification Stay rod material: U24 – 24daN/mm2

α=60° Classification of stay

L Length of rod

(m)

D Diameter (mm) H (cm) h (cm)

Stay block

L (Light) 2.1 12 155 55x55x15 M (Medium) 2.5 22 190

30 100x100x15

Guy wire classification Material: Steel wire, 7-wire; twisted to the right

Classification of stay L (Light) M (medium) Section (mm2) 20 64

guy wire diameter (mm) 5 9 Ultimate load (daN) 1700 6000

α

h

L

φD

H


- 7-12 -

7.6 Conductors and Cables

7.6.1 Advantages/Disadvantages of Conductors and Cables

The feature of conductor and cable is shown at following table Advantages Disadvantages

conductors - cheap - easy to connect each conductor

- not safety

cables - safety - able to lay underground

- expensive - difficult to connect each cable

7.6.2 Sizes of Conductors

Sized of conductors should be selected taking into account amount of present load,

forecasted load, short-circuit current, current capacity of conductors, voltage drop,

power loss, mechanical strength, etc. Too many sizes shall not be used for branch

feeders.

7.6.3 Allowable Sag of Conductors

Conductors sag is to be determined taking into account the allowable conductor tension,

strength of the supporting structures, wind load on conductors, etc. Conductors sag is

needed to be keep the height above ground as following table: Conductor height above ground 20 kV Low Voltage

Road crossing 6.5 m 4.0 m Along road 6.0 m 4.0 m Other places 6.0 m 4.0 m

7.6.4 Allowable Load per Phase

3-phase distribution lines are needed to keep the load balanced. If the unbalance load

become more 20%, instruments receive a bad influence.

7.6.5 Application of 3-Phase Line

To avoid above things, it is desirable that 3-phases distribution line is expanded to

villages of demand. If it is not possible to do because of the cost, we need to give

attention to keep the balanced load.


- 7-13 -

7.7 Distribution Transformers

In case 20kV distribution line is required instead of 380/220V line due to long distance

from power station to consumers with the reason of sending capacity, voltage drop etc.,

some step-up and step-down transformers shall be installed. The connection of both

step-up and step-down is completely similar. Step-up transformer is installed at power

station side for step-up from 380/220V to 20/11.5kV and step-down transformer is

installed at consumer’s area for step-down and vice versa.

7.7.1 Types of Distribution Transformer

Distribution transformers are classified into the type of insulation, as follows:

Oil immersed transformer: Windings are immersed in insulation oil in tank and

cheaper.

Dry type transformer: Windings insulated with heat-resisting epoxy (H-class)

without tank but expensive.

Distribution transformers are classified into two kinds by winding method as follows

Three-phase transformer: λ - λ connection Suitable for grounding of neutral point

Δ- λ connection

Δ-Δconnection

Note: Δ; Delta connection λ; Star connection

Single phase transformer: Usually used for voltage step-down from 20/11.5kV to

220V near consumer’s area.

Single phase transformer can be also used both star and delta connection by outside

connection with combination of 3 nos. transformers


- 7-14 -

7.7.2 Necessity of Transformers

1) At first, measure the distance from powerhouse to each center of community.

distance a (km)

distance b (km)

distance c (km)

distance x (km)

2) Calculate load current I of each distribution line (A)

IXA , IXB , IPX = IXA+ IXB , IPC

Here in,

Pa [kVA]: load from X to A (power of each household×number of household)

VLV [V]: Low Voltage

3) Calculate voltage drop of each cable

VXA [V] = IXA×0.443×a

VXB [V] = IXB×0.443×b

VPC [V] = IPC×0.443×c

VPX [V] = IPX×0.443×x

Resistance of 70 mm2 conductor = 0.443 [Ω/km]

4) Calculate total voltage drop

Power house to A village: VXA + VPX = VA

If VA < (VLV× percentage of voltage drop), it is not necessary transformer.

Power house to B village: VXB + VPX = VB,

If VB < (VLV× percentage of voltage drop), it is not necessary transformer.

Power house to C village: VPC,

If VPC < (VLV× percentage of voltage drop), it is not necessary transformer.

PH

X

c (km)

A village

B village

C village

a

b

x

LVV

P

3

103a

LVV

P

3

103b

LVV

P

3

103c


- 7-15 -

7.7.3 Application of Distribution Transformers

Step-up and step-down distribution transformers shall be of three-phase construction,

and their standard capacities are as follows:

5 kVA, 10 kVA, 16 kVA, 25 kVA, and 50 kVA

7.7.4 Selection of Unit Capacity

Capacity of transformer should be decided 125 % (= 100 % / 80 %) of the capacity of

generator, If the power factor is 80 %. The maximum loading is 100%, and over loading

shall not be allowed so as to impair life of transformers. The transformers tend to be

used long time till their breakdown without regular maintenance. Following table shows

the relation between capacity of transformer and generator.

Table 7.7.1 Relation between capacity of transformer and generator Capacity of Transformer

5 kVA 10 kVA 16 kVA 25kVA 50kVA

Capacity of generator

-4 kW 4 kW – 8 kW

8 kW – 12.8 kW

12.8kW – 20 kW

20kW - 40 kW

Before deciding the unit capacity of new transformers, the supply area of new

transformers is to be determined taking into account the followings:

(a) Supply area of new transformers shall not overlap with that of other transformers

supplied from other feeders.

(b) Supply area of each transformer must be independent.

(c) Voltage drop restriction should be satisfied at any part of the supply area.

The capacity of new transformers should be determined taking into account the

expected demand growth of the area, however the smallest capacity that satisfies present

demand in the area is generally applied.

7.7.5 Location

Step-up transformers shall be located near the powerhouse. Step-down transformers

shall be located in or close to the load center of the area. In deciding the final location to

install transformer, the following conditions should also be examined:

(a) Easy to access and replacement works.

(b) To be separated from other buildings or trees with enough clearance.

(c) For pole mounted type, pole assembly shall not be complicate.

(d) Ground mounted type structures shall be constructed so as to avoid troubles with

public.


- 7-16 -

7.8 House Connection (HC)

7.8.1 Application of House Connection

For HC, copper core or aluminum core twisted cable will be used.

The sizes of the copper core are: 4 mm2; 6 mm2; 10 mm2; 16 mm2; 25 mm2

The sizes of the aluminum core are: 10 mm2; 16 mm2; 25 mm2; 35 mm2

It is preferred not to use a roof pole with the customers entrance line placed as such that

it can be seen from the outside. The use of a roof pole is only to serve the connection

from house to house or a house that is not situated on the same side of the street with the

LVL, so that a roof pole is needed.

The minimum clearance is 3 m for compounds, 4 m for public road, if the height of the

house is less than 3 m, a roof pole will be used as such that requirement for clearance is

met.

However, if by using a roof pole it appears that the minimum clearance is not met, a

supporting pole should be used for such house connection.

The wires of the smallest sectional area shall be used from the following considerations:

(a) Capacity of the wire is sufficient to carry peak load current

(b) Voltage drop criterion is satisfied.

The Maximum voltage drop calculated for HC is as follows:

- For HC tapped from LV, the maximum voltage drop for HC is 2 %.

- For HC tapped directly from the transformer, the maximum voltage drop for HC is 12 %.

The house connection span is as following table. From roof pole to roof

pole From LVL pole to roof pole crossing the village road

From LVL pole directly to house crossing the village roadSection

(mm2) A (m) T (daN) S (m) a (m) T (daN) S (m) a (m) T (daN) S (m)

10 16 25

40 35 35

38 42 63

0.78 0.84 0.84

58 47 47

38 42 63

1.66 1.49 1.49

49 40 40

38 42 63

1.18 1.11 1.11

in which : a = span length (m)

S = sag (m)

T = pull/tension (daN)

Assumption: Wind intensity = 40 daN/m2

Strength of roof pole: 76 daN

Factor of cable shape with regard to wind = 0.6


- 7-17 -

Width of village road = 6 m with pavement on the right and left = 1 m

Clearance over the road = 4 m

Refer to Ref. 7-2 about construction of house connection crossing village road.

7.8.2 In-house Wiring

The typical wiring in house is shown in Figure 7.8.1.

The expected power consumption in each household is 150-200W composed of

following facilities:

1) Single phase MCB (Molded Circuit Breaker) for protection of short circuit and

earth fault.

2) 2pcs. of ceiling lamp with on-off switch

3) 1 pc. of entrance lamp with on-off switch

4) 1 pc. of outlet for general use of electrical facilities

Figure 7.8.1 Typical In-house Wiring Diagram

R,S,TN

MCB

Lamp

Double Switch Angle Switch Electric Socket

Lamp Lamp


- 7-18 -

[Ref. 7-1 Standard of Steel Poles]

Work Load (daN) 100

A 89.1 B 114.3

Diameter of pole sections (mm)

C 139.8 A 3.2 B 3.5

Pipe thickness (mm)

C 4.5 Diffraction at work load (mm)

96

Cartridge thickness (mm) 5 Cartridge length (mm) 600

4,000

1,500

1,500 A

B

C

1,160

300

100

E : Welded part

F : Sock-pen

G : Holding plate

G

F

E


- 7-19 -

[Ref. 7-2 Construction of house connection crossing village road]


- 7-20 -


- 7-21 -


- 8-1 -

Chapter 8 PROJECT COST ESTIMATION

8.1 Rough Cost Estimation During Planning Stage

When you are going to make a trial calculation of construction cost in Planning Stage, it

can be calculated by the method shown in Table 8.1.2. However, before calculating, it is

necessary to carry out a field survey for confirmation and decide the item mentioned to Table

8.1.1.

Table8.1.1 Items to make a trial calculate of construction cost

Description Item Plan Maximum Out Put (kW) Turbine Discharge (m3/s) Effective Head (m) Intake Facilities Height of Dam (m) Length of Dam (m) Headrace Length of Headrace (m) Penstock Diameter of Penstock (m) Distribution Number of Households (kk) Distance to the most far house from P.S

In addition, indirect costs, such as Tax, Contractor Fee, Design Cost, and Supervisor, are

contained in the cost of construction calculated by Fig 8.1.2. When part of these indirect costs

can be omitted explanation is required separately.


- 8-2 -

Table 8.1.2 Rough Calculation of Construction Cost During Planning Stage

No. Description Formulae Remarks

(1) PREPARATORY WORKS {2 + 3 + 4 + 5 }*0.1 Transportation, Clearing,

Temporary Works

(2) CIVIL WORKS 1 to 7

1 Intake Facilities Gabion Dam H: Height of Dam(m)

1,400 x H x L L: Length of Dam(m)

Stone masonry dam H: Height of Dam(m)

5,350 x (HxL)+5,800 L: Length of Dam(m)

Concrete Dam H: Height of Dam(m)

11,300 x H x L L: Length of Dam(m)

2 Settling Basin Long or Mid-Penstock Q: Turbine Discharge (m3/sec)

414,500 x Q 0.504 (see system layout)

Short Penstock Q: Turbine Discharge (m3/sec)

372,600 x Q 0.794 (see system layout)

3 Headrace 2,950 x Q 0.18 x L Q: Turbine Discharge (m3/sec)

L: Length of headrace (m)

4 Head Tank 327,200 x Q 0.5 Q: Turbine Discharge (m3/sec)

5 Penstock Civil Works φ: Diameter of Penstock (m)

5,300 x φ 0.571 x L L: Length of Penstock (m)

Penstock L: Length of Penstock (m)

100 x Unit wt. x L

6 Power house 33,600 x P 0.456 P: Maximum Output (kW)

Foundation (include tailrace)

7 Power house 16,900 x P + 139,900 P: Maximum Output (kW)

Building

(3) ELECTROMECHANICAL 520,500 x (P/√He)0.56 Cross Flow Turbine T-13

WORKS P: Maximum Output (kW)

He: Effective Head(m)

(4) DISTRIBUTION WORKS 95 x X 0.5541 X: No. of HH x Distance2

(5) HH CONNECTION 2,900 X + 219,300 X: No. of Household

(6) OTHERS {(2)+(3)+(4)+(5)}*0.05

TOTAL (1)+(2)+(3)+(4)+(5)+(6)


- 8-3 -

8.2 Cost Estimation During Detail Design Stage

Construction cost consists of items as shown in Table 8.2.1.

8.2.1 Items

Typical items of a direct cost are the following.

(1) Preparatory Works Preparatory Works consist of item as follows. - Location Setting Out - Filling and Measurement - Equipment & Materials Mobilization

(2) Civil Works

Civil Works consist of item as follows. - Intake facilities - Settling basin - Headrace - Head tank - Spillway - Penstock and Foundation - Powerhouse base - Tailrace - Power house building - Finishing

(3) Electro-Mechanical Works Electro-Mechanical Works consist of item as follows.

- Turbine - Controller - Dummy load - Generator - Accessories, Spare parts and Tools - Set up and Installation


- 8-4 -

- Transportation and Packing - Testing - Pre commissioning Trial Run

(4) Distribution Works

Distribution Works consist of item as follows. - Transmission pole - Cable - Transformer - Accessories

(5) Consumer Connection

- Cable - Switch - Accessories

Table 8.2.1 Construction Cost

No. Item Cost

Direct cost of construction

1 PREPARATORY WORKS Addition item

2 CIVIL WORKS Addition item

3 ELECTRO-MECHANICAL WORKS Addition item

4 DISTRIBUTION WORKS Addition item

5 CONSUMER CONNECTION Addition item

SUB TOTAL(A)

Indirect cost

1 DESIGN FEE 5～10% of SUB TOTAL(A)

2 SUPERVISOR FEE 5～10% of SUB TOTAL(A)

3 MANAGEMENT FEE 5～10% of SUB TOTAL(A)

4 TAX 12.5% of SUB TOTAL(A)

SUB TOTAL(B)

TOTAL


- 8-5 -

8.2.2 Quantity

In order to calculate the direct cost of construction, it is necessary to calculate the quantity for

every work or material based on the design. For example, in case of Headrace made of stone

masonry, quantities of excavation, foundation rubble stone, stone masonry, backfill, and

plastering, as illustrated in Figure 8.2.1 below, shall be estimated.

Fig 8.2.1 The example of works that should be estimated（Headrace）

Naturally, these items change according to the type and the quality of structure. For example,

in Intake, the items that should be calculated is in accordance with the type of Dam as shown

in Table 8.2.2. And in Headrace, the item which should calculate will be changed according to

the quality of the material of Headrace like Table 8.2.3.

Excavation

Foundation Rubble Stone

Stone Masonry Backfill Plaster


- 8-6 -

Table 8.2.2 Quantity of Dam

Gabion Dam Masonry Dam Concrete Dam - Excavation (m3) - Backfill (m3) - Gabion (m3)

- Excavation (m3) - Backfill (m3) - Foundation Rubble

Stone (m3) - Stone Masonry (m3) - Plaster (m2) - Stoplog (m2) - Gabion (m3)

- Excavation (m3) - Backfill (m3) - Sand filling (m3) - Concrete (m3) - Plaster (m2) - Stoplog (m2) - Gabion (m3)

Table 8.2.3 Quantity of Headrace

Simple earth channel Masonry channel Concrete channel - Excavation (m3) - Excavation (m3)

- Backfill (m3) - Foundation Rubble

Stone (m3) - Stone Masonry (m3) - Plaster (m2)

- Excavation (m3) - Backfill (m3) - Sand filling (m3) - Concrete (m3) - Plaster (m2)

8.2.3 Unit Cost

Table 8.2.4 is the standard unit cost per work item of civil work of a project in certain area.

Since unit cost differs according to various regions in which the project is located, it is

advisable to leave the unit cost per work item blank to be filled up with the prevailing costs in

the area.


- 8-7 -

Table 8.2.4 Unit Cost per work item

Unit 1 m3

Unskilled Labor man-day 0.625 0 0Foreman man-day 0.062 0 119Tools ls 1.000 4

Sub Total 123Tax for Labor 12 10% of Labor CostOthers 8

Total 143Unit Cost/m3 143

Unit 5.000 m2

Unskilled Labor man-day 1.125 0 0Skilled Labor man-day 0.563 0 0Foreman man-day 0.056 0 0Sand m3 0.400 100 40 Stone m3 1.200 100 120Tools ls 1.000 5


Total 169

Unit Cost/m2 34 Total/5m3

Unit 1 m3

Unskilled Labor man-day 2.250 0 0Skilled Labor man-day 1.125 0 0Mason man-day 0.113 0 0Foreman man-day 0.017 0 0Rubbles m3 1.000 100 100Sand and Gravel (mix) m3 0.380 100 38Portland Cement bags 3.520 200 704Hauling ls 84 10% of Material CostTools ls 1.000 28



Work Item Unit

(1) Excavation

Coefficient Price Unit Cost Remark

(2) Foundation Rubble Stone (T=20cm)

Work Item Unit Coefficient Price Unit Cost Remark

(3) Stone Masonry 1:2 (Intake Weir)



- 8-8 -

Unit 1 m3

Unskilled Labor man-day 2.250 0 0Skilled Labor man-day 1.125 0 0Mason man-day 0.113 0 0Foreman man-day 0.017 0 0Rubbles m3 1.000 100 100Sand and Gravel (mix) m3 0.400 100 40Portland Cement bags 2.840 200 568Hauling ls 71 10% of Material CostTools ls 1.000 23



Unit 1 m3

Unskilled Labor man-day 2.250 0 0Skilled Labor man-day 1.125 0 0Mason man-day 0.113 0 0Foreman man-day 0.017 0 0Rubbles (Excavated) m3 1.200 100 120Sand and Gravel (mix) m3 0.400 100 40Portland Cement bags 2.500 200 500Hauling ls 66 10% of Material CostTools ls 1.000 22



Unit 1 m2

Unskilled Labor man-day 0.286 0 0Skilled Labor man-day 0.214 0 0Foreman man-day 0.020 0 0Sand m3 0.019 100 2Portland Cement bags 0.237 200 47Hauling ls 5 10% of Material CostTools ls 1.000 2



(4) Stone Masonry 1:3


(5) Stone Masonry 1:4


(6) Plastering (t=3cm)



- 8-9 -

Unit 1 m3

Unskilled Labor man-day 0.450 0 0Skilled Labor man-day 0.200 0 0Foreman man-day 0.020 0 0Rubbles m3 1.200 100 120Wire Cage kg 3.500 200 700Hauling ls 82 10% of Material CostTools ls 1.000 27



Unit 10 m3

Unskilled Labor man-day 25.000 0 0Skilled Labor man-day 2.500 0 0Foreman man-day 1.110 0 0Portland Cement bags 75.000 200 15,000Sand m3 4.900 100 490Gravel m3 8.100 100 810Hauling ls 1,630 10% of Material CostTools ls 1.000 538

Sub Total 18,468Tax for Labor 0 10% of Labor CostOthers 83

Total 18,551Unit Cost/m3 1,855

Unit 1,000 kg

Labor Steel man man-day 12.000 0 0Foreman Steel man man-day 1.200 0 0Steel Bar kg 1000.000 47 47,000Tie Wire kg 20.000 60 1,200Hauling ls 4,820 10% of Material CostTools ls 1.000 1,591


Total 55,458Unit Cost/kg 55

(7) Gabion


(8) Concrete


(9) Reinforce Bar



- 8-10 -

Unit 100 m2

Carpenter man-day 25.000 0 0Carpenter Foreman man-day 2.500 0 0Form Plywood(1/4"*4'*8'=0.6*1200*2400=2.88m2)clas pcs 34.722 113 3,935 3 time useForm Lumbers(1"*2"*6') bd ft 196.000 12 2,287 3 time useCWNails kgs 20.000 60 200 Hauling ls 1.000 642 10% of Material CostTools ls 212


Total 7,355Unit Cost/m2 74

Unit 3.00 m2

Carpenter man-day 1.000 0 0Form Plywood(1/4"*4'*8'=0.6*1200*2400=2.88m2)Nar pcs 1.042 540 563Tools ls 17



Unit 1.00 unit

Unskilled Labor man-day 4.000 0 0Foreman man-day 1.000 0 0Welder man-day 1.000 0 0Welding machine & Generator day 1.000 1500 1,500Tools ls 1.000 45


Total 1,635Unit Cost/m2 1,635

(12) Installation of Penscock Pipe


(11) Stoplogs


(10) Form work



- 8-11-

[Ref. 8-1 Cross-sectional method to calculate quantity]

It is convenient if you use Cross-sectional method when calculating complicated quantity such a Headrace. When you want to calculate the quantity of excavation of Headrace as shown in the following figure, first, you draw a sectional view for every changing point of cross-sectional form, and the excavation area for every section is calculated using planimeter etc.


- 8-12-

Next, you can make the next table from the relation between the area of each section, and distance.

This cross-sectional method is applicable not only excavation area but also in the calculation of quantity of Backfill or Masonry.

Section name Excavation Area Average Area Distance Volume

① ② ③ ②×③

Total 12.73m3

2.690m3

4.125m3

3.735m3

2.180m3

E - E

2.00m

3.00m

3.00m

2.00m

A - A

B - B

C - C

D - D

1.37m21.375m2

1.245m2

1.12m2

1.090m2

1.06m2

1.345m21.31 m2

1.38m2


- 8-13-

[Ref. 8-2 Example of Bill of Quantities]


- 8-14-


- 8-15-


- 8-16-


- 8-17-


- 9-1 -

CHAPTER 9 CONSTRUCTION MANAGEMENT

9.1 Construction Management for Civil Facilities

9.1.1 Purpose

Construction management is performed by the contractor to satisfy the standards and to

complete the construction works economically and safely within the construction period.

For assuring the quality and functions and for controlling the progress of work, the

contractor makes a construction plan, checks in the middle of work whether the work is

being carried out as scheduled, makes corrections if the work is delayed, examines

whether the predetermined quality and shape are being made and shows the results on

graphs and tables, corrects the items not meeting standards or the like, and records the

progress, quality and shape of the work in comparison to the specifications and

drawings.

Construction management includes progress control, dimension control and quality

control.

9.1.2 Progress Control

Progress control is the management of construction process for assuring the execution

of work efficiently and economically within construction period by effectively utilizing

the machines, labour and materials while maintaining sufficient quality and accuracy

instead of merely controlling a series of processes for observing the completion date. In

particular, in countries where a rainy season and a dry season can be clearly recognized,

the construction works are concentrated in dry season and this will impose extra

restrictions on time, and thus progress control must be given paramount importance.

This is important because it is unavoidable to rely mainly upon manpower in civil

works. On the other hand, hydropower station construction contains works for generator

installation and electric facility construction in addition to civil works, and so close

coordination between the works is required.

When using funds from international financial institutions for importing construction

equipment and materials, various procedures are necessary to obtain approvals from

relevant agencies for the import plan, to prepare documents necessary for international

bidding, to make documents for bidding and contracting by export/import agents and to

obtain approvals for export from the government of the country exporting the goods.

When preparing a time schedule for construction, it should be noted that a considerable


- 9-2 -

period of time is necessary from the start of taking the above procedures to the actual

delivery of goods to the site.

(1) Procedure of progress control

Progress control is made for each of the planning, implementation, reviewing and

handling steps. Progress should be controlled to execute the works as close as possible

to the schedule by carrying out the work in accordance with the construction schedule,

and periodically recording the actual progress on schedule sheets every day, every week

or every month and constantly checking the progress by comparing the planned and

actual progress. If any large deviation is detected between the two, there may be a

problem in the plan or implementation system. Thus, the plan should be reexamined and

correcting measures taken. Then, implementation, reviewing and handling steps should

be taken on the basis of the revised construction schedule.

(2) Construction schedule chart

Various time schedules should be graphically prepared for progress control and then

used as standard for implementation, review and handling. The following forms are

normally used for the control chart.

(a) Horizontal line type schedule charts (Gantt chart, bar chart)

(b) Curve type schedule charts (graph type)

(c) Network type schedule charts (PERT, CPM)

Bar charts are normally used as schedule charts but the use of network type schedule

charts is more advantageous in power station projects where various types of works

overlap. For knowing the shape (dimensions, quantity, reference height, etc.) of an

object created by the works, the shape is directly measured

9.1.3 Dimension Control

It is necessary to ensure that the civil works have been built in conformity with the

contract requirements set forth and intended by the owner. If any items not meeting the

requirements are found, the causes should be pursued and corrective measures taken.

Dimension control can be roughly divided into direct-measurement and photo-graphic

records.

(1) Direct measurement

For knowing the shape (dimensions, quantity, reference height, etc.) of an object created

by the works, the shape is directly measured in accordance with the sequence of

construction works and the measured values are then compared to design values. The


- 9-3 -

results are recorded, the accuracy of construction cheeked against standards, and the

degree of construction technology controlled.

(2) Photographic records

Photographic records are made as supplementary data for later confirmation of the

progress of the works including conditions before and after the works, the portions that

may not be seen upon completion of the structure, and the results of direct

measurement.

9.1.4 Quality control

Quality control is used to maintain the standards of quantity set forth in the design and

specifications.

(1) Procedure of quality control

For performing quality control, standardization must first of all be made. Standards or

criteria should be established for all the phases ranging from material purchasing to

work execution, and the works should be controlled in accordance with it.

(a) Standards for materials

Quality standards for materials to be used should be clarified and quantitatively defined.

(b) Quality standards

Control characteristics for the required quality should be clarified and quantitatively

defined.

(c) Work standards

Facility handling standards, inspection standards and standards for working methods

should be determined.

(d) Test and inspection methods

Standards for tests and inspections should be established.

As stated above, it is necessary to establish material standards, use the materials of

predetermined quality and perform the work, inspection and test in accordance with the

predetermined methods satisfying quality standards.

(2) Quality characteristics

Examples of quality characteristics and test items for the required quality control are

shown in Table 9-1


- 9-4 -

Table 9.1.1 Examples of quality characteristics

Kind Quality characteristics Tests Concrete Slump

Air Content Compressive strength Bending strength

Slump test Air content test Compression test Bending test

Earth Grain size Degree of compactness Penetration index In-situ CBR value

Grain size analysis Dry density test Various penetration tests In-situ CBR test

Asphalt Density and voids Temperature at delivery to site Flatness of pavement surface

Marshall test Temperature test at delivery to site Flatness test

(3) Control method

Typical quality control methods are as explained below.

(a) Histogram

For finding the distributing conditions of certain characteristic values of products, the

measured values of required samples should be obtained and bar graphs prepared.

Histograms are convenient for judging whether the quality characteristics satisfy the

standards, whether the product distribution has certain allowance from the standards,

and whether the distribution of the overall quality is appropriate.

(b) Control chart

Control charts have a wide application range, are useful among quality control methods

and are therefore the most frequently utilized. Control charts show pairs of control

limits and, if any plotted points are located outside the limit, this means that there is a

critical quality fluctuation.

Control charts are classified as shown below depending on whether the items being

considered are continuous data such as length, strength and weight or discrete values

such as fraction defective ratio, number of defective portions and number of defects.

Control charts

for continuous data ......... X control chart, X control chart, X

control chart, R control chart,

process capability chart.

Control charts

for discrete values ......... P control chart, Pn control chart, C

control chart, U control chart

~ _


- 9-5 -

9.2 Construction Management for Turbine, Generator and their Associated

Equipment

9.2.1 Installation

(1) Heavy machinery

Heavy machinery (suited to the weights to be lifted) of the required number for

transporting materials, parts and equipment on the site should be secured for the

required period of time. The heavy machinery should include machines for loading,

unloading, hauling and handling loads inside power station.

(2) Manpower of direct labourers and technicians

The number of direct labourers and technicians required varies depending on the types,

capacities, sizes and installation method of turbine and generator, equipment

configuration, delivery route, heavy machinery available, working environment and

experience of contractor. The numbers of direct labourers and technicians required

are roughly estimated as follows. The installation period also varies depending on the

above items but approximately 2 to 4 months will be needed normally.

(Skilled labourers)

Foreman: Mechanics: Welders: Pipe fitters: Rigger: Crane & heavy machinery operators: Electricians:

1 3 to 4 1 to 2 1 to 2 1 1 to 2 2 to 3

(Unskilled labourers) Odd-jobbers: 5 to 6

(3) Temporary facilities

The following temporary facilities should be considered:

(a) Distribution board for temporary power source

(b) Lodging facilities

(c) Warehouse

(d) Site construction office

(4) General tools and consumables


- 9-6 -

(5) Classification of installation work

(a) Inspection of dimensions and level of concrete foundation

(b) Transport of materials, parts and equipment from warehouse to power station

(e) Unpacking

(d) Preparing scaffolds

(e) Assembly and installation

(f) Welding and gas cutting

(g) Wiring

(h) Piping work and flushing

(i) Hydraulic pressure test

(j) Non-destructive test

(k) Centering, leveling

(1) Shaft runout test

(m) Painting

(6) Inspection during installation

(a) Centering & leveling

(b) Shaft runout measurement

(c) Measurement of caps of rotating parts

(d) Confirmation of dimensions of each portion

(e) Dye Penetration Test or ultrasonic crack examination for field welds of stress

carrying parts

(f) Relation between guide vane opening and servomotor stroke

(g) Insulation resistance measurement

9.2.2 Adjustment during Test Run Operation

(1) Instruments, tools and materials

Prior to cdommencement of the tests, provision should be made for dummy load by

water rheostat or the like if an actual load for the tests can not be expected.

(2) Manpower schedule

Occupation Number of Personnel Test engineers (mechanical): Test engineers (electrical): Testing personnel:

1 to 2 1 to 2 10 to 12


- 9-7 -

Test period

This varies depending on the types of turbine and generator, equipment configuration,

experience of testers but is normally 1 to 2 months.

(3) Test items

(a) Appearance inspection

(b) Insulation resistance measurement

(c) Withstand voltage test

(d) Tests for turbine ancillary equipment

- Performance test for governor

- Tests for oil pressure supply and lubricating systems

- Tests for water supply and drainage systems

(e) Exciter combination tests

(f) No-water overall tests

(g) Water filling tests

(h) Initial running tests

(i) Automatic start and stop tests

(j) Synchronizing tests

(k) Load rejection tests

Safe stopping after rejection of loads during operation should be confirmed mainly

for the pressure change in the penstock, machine speed change and voltage change

of generator.

(1) Output and opening tests

It should be confirmed that there are no abnormal phenomena within operating load

range, and that the discharge and output satisfy the specifications.

(m) Vibration measurement

To be performed during output and opening tests.

(n) Load tests

Continuous operation should be made under full load until the temperature of the

coils and bearings of the generator stabilizes.

Manual for Micro-Hydro Development Chapter 10

- 10-1 -

Chapter 10 OPERATION AND MAINTENANCE 10.1 Introduction

A hydropower plant has an advantage that it does not need fuel for its operation as

compared with oil or thermal power plants. However, there are no differences between

both type of plants on that appropriate operation and maintenance (O&M) are essential

for their long-term operation. It can be operated for long period if its facilities are

properly operated and maintained. We should effectively utilize hydropower because

aside from being indigenous energy resource, it is also renewable.

We have to operate and maintain micro hydropower plants with strict compliance to the

operation and maintenance manuals. In general, operators of micro hydropower plants

should be trained to understand the following:

（１）Operators must efficiently conduct operation and maintenance of the

micro-hydropower plant with strict compliance with the O and M rules and

regulations.

（２）Operators must familiarize themselves with all the plant components and

their respective performance or functions. Furthermore, they should also be

familiar to measures against various accidents for prompt recovery.

（３）Operators must always check conditions of facilities and equipment. When

they find some troubles or accidents, they must inform the person in charge

and try to recover it.

（４）Operators must try to prevent any accidents. For the purpose, they should

repair or improve facilities preventively as necessary.

Operation and maintenance manual should basically be prepared for each plant

individually before the start of its operation. Following is the general manual of

operation and maintenance for micro hydropower plants.


- 10-2 -

10.2 Operation

The operation of micro-hydropower plants is not only to generate electric power but

also to control generation equipment and to supply electricity of stable quantity and

quality to consumers and maintaining all facilities in good condition.

The micro-hydropower plant facilities and equipment were installed depending on site

conditions and budget, but there are various ways of proper operation for these plants.

For a plant that is equipped with an automatic load stabilizer, the operators do not

always have to control the equipment except in case of starting, stopping and during

emergency cases. And in case automatic stopping and recording systems are installed, it

is not necessary for operators to stay in the power plant most of the time.

However, most of micro-hydro plants for rural electrification are not provided with

automatic control system and protection equipment because of budget limitation. In this

case, it is necessary for operators to stay at or near the plant to monitor control

equipment and to undertake immediate measures in case of emergency, in the

observance of proper operation practice.

General ways of micro-hydro operations are as follows:

10.2.1 Basic operation

（１） Check points before starting operation

Before starting operation of the power plant, operators must check the

following facilities are in good condition for operation. Especially in the

case of after long term operation, they should be checked thoroughly.

① Transmission and distribution line

・ Damages of lines and poles

・ Approaching branches

・ Other obstacles

② Waterway facilities

・ Damages of structures

・ Sand sedimentation in front of the intake

・ Suspended trash at screens

・ Sand sedimentation in the settling basin and the forebay


- 10-3 -

③ Turbine, generator and controller

・ Visual inspection

・ Wear of brush

・ Insulation resistance of circuits

（２） Starting operation

After checking the turbine and generator are okay for operation.

Procedure of starting operation is as follows:

（Preparation）

① Close the flushing gate of the intake weir

② Open the intake gate and intake water into the waterway system.

（Starting operation）

③ Open the inlet valve gradually.

④ If there is a guide vane, open the inlet valve fully, and then open the

guide vane gradually.

⑤ Confirm that voltage and frequency or rotating speed increase up to

the regulated value.

⑥ Turn the load switch on (parallel in)

⑦ Control inlet valve or guide vane so that voltage and frequency are

within the regulated range.

（３） Role of operators during operation

Operators must control equipment in order to supply electricity of good

quality keeping equipment normal and safe as follows:

① Control the inlet valve or guide vane so that voltage and frequency are

within the regulated range.

② Check vibration and noise of equipment, and then stop operation if

necessary.

③ Check temperature of equipment

④ Check any abnormal condition of equipment, and then stop operation

and take a measure if necessary.

⑤ Record result of operation and condition of equipment according to

fixed format.


- 10-4 -

（４） Stopping operation

In order to avoid longer runaway speed of the turbine and the generator, the

procedure of stopping operation is as follows:

① Close the inlet valve or the guide vane.

② Cut load switch off (load rejection)

③ Close the inlet valve and the guide vane completely.

④ Close the intake gate

When load is suddenly cut due to an accident, operator must close the inlet

valve or the guide vane immediately to avoid runaway speed of the turbine

and the generator for long time.

10.2.2 Operation in case of Emergency

（１）In case of flood

In general, micro hydropower plants can be operated even in the case of

flood, however, when the river becomes muddy and if there is possibility

that sand and soil will enter into the facilities, operation of the plant should

be stopped by closing the intake gate. After flood, operators must inspect all

facilities first prior to resumption of operation.

（２） In case of earthquake

Since an earthquake affects all facilities of plants, operators must inspect

facilities after a big earthquake as follows:

・ Check damages of structures

・ Misalignment of the shaft of the turbine and the generator

・ Damages of other electrical equipment

・ Others

（３） In case of shortage of water

There is an applicable range of water discharge for each turbine. Therefore,

a turbine should be operated within the range.

Micro hydropower plant should basically be designed along water discharge

in the dry season. However, in case of shortage of water that is beyond of

our expectations, operators must stop operation because continuous

operation under such condition will damage the turbine.


- 10-5 -

（４）In case of accident

In case of accident, operators must stop operation, investigate the cause

and try to recover operation as soon as possible. Operator’s roles are as

follows:

① Immediately inform the accident to the person in charge.

② Investigate accident in detail.

③ Look into the causes of accident.

④ Recover operation as soon as possible if operators can prove the causes

and repair by themselves.

⑤ Contact makers or suppliers of equipment and request them to repair if

the operators cannot find the causes and cannot repair by themselves.

What operators should prepare in advance are as follows:

・ Discuss with maker or supplier of equipment on possible measures in

case of equipment trouble.

・ Present to the Barangay Alternative Power Association (BAPA)

management about expenditure on the recovery.

⑥ Inform the DOE and LGU regarding the accident.

10.2.3 Others

（１）Filling water in waterway system

Procedure of filling water into the waterway system is as follows:

① Confirm all flushing gates and valve of the water system are open.

② Open the intake gate partially, and intake small volume of water.

③ Close the flushing gate of the settling basin after cleaning the

settling basin.

④ Close the flushing gate of the forebay after cleaning the headrace

and the forebay.

⑤ Close the drain valve of the penstock after cleaning the penstock.

⑥ Fill the penstock with water gradually.

⑦ Open the intake gate fully after filling up the penstock.

( 2 ) Flushing sand in front of intake

If sand sedimentation reaches the intake level, sand will be carried into


- 10-6 -

waterway system and it will affect the penstock and turbine blades.

Therefore, in order to prepare against outflow of sand and soil during

flooding, operators must keep the intake approach open. For the purpose,

operators should sometimes flush or remove sand that settled in front of

intake.

If flushing gate is installed at the intake weir, operators can flush sand

out by water flow opening the gate during flooding. However, incase of

having no flushing gate, operators must remove sand out of the weir

manually.

( 3 ) Control of intake water

Volume of intake water changes according to water level of river.

Normally excess water should be spilled out at spillway, which is

located at settling basin or headrace. If the excess water reaches the

spillway of the forebay for long time, it may possibly wash out the

structure due to lack of spillway capacity. Therefore, operators must

control the intake gate so as to avoid too much water spill.

10.3 Maintenance

In order to operate micro hydropower plants in good condition for long period,

waterway facilities, electric equipment, transmission and distribution line should be

maintained adequately. Operators must try to observe even a small trouble and

prevent accident of facilities. For the purpose, daily patrol and periodic inspection

are essential and recording and keeping of those data are also important.

Though items and frequency of patrol and inspection should be decided considering

condition of facilities and ways of use, general maintenance of micro hydropower

plants is as follows:

10.3.1 Daily patrol

In order to check if there is anything strange at waterway facilities, electric

equipment, transmission and distribution line, operators daily conduct patrol along

the course that has been fixed in advance. Operators must record result of patrol and

take a measure if necessary.


- 10-7 -

Items of daily patrol are as follows:

Facilities and Equipment Checking Points Measures Suspended Trash at screen

To remove it at any time

Water leakage from weir and gate

To record it To repair it if necessary

Sand sedimentation To flush it out as necessary

Intake and Waterway

Deformation or Crack in structure


Sedimentation Basin Sand sedimentation To flush it out as necessary

Facilities and Equipment Checking Points Measures Suspended materials along canal



Leakage, deformation and Crack in structure


Headrace

Land slide along headrace

To remove sand and rocks after confirming safety

Suspended Trash at screen


Overflow from Spillway

To reduce water intaken if overlowing water is too much.

Water leakage To record it To repair it if necessary


Headtank (Forebay)



Penstock Leakage and deformation

To record it

Strange sound and vibration

To record it To check the causes of it

Turbine

Leakage from housing


Strange sound and vibration

To record it To check the causes of it

Temperature To record it

Generator

Damage of belt To replace if necessary Performance of load stabilizer

To check the performance Load stabilizer

Damage of heater To replace if necessary Transformer Leakage of oil To replace if necessary

Suspended material To remove after stopping the operation

Transmission and Distribution line

Approaching branch To cut it as necessary


- 10-8 -

10.3.2 Periodic Inspection

Operators must conduct inspection periodically to check if there are any troubles in

facilities and equipment. Operators, preferably, should be able to perform repair

works in case there are troubles during inspection, if necessary.

Items and frequency of periodic inspection are as follows:

Facilities and Equipment Checking Points Frequency

Measures

Leakage, deformation and Crack in structure

6 months To record it To repair it if necessary

Intake ～ Penstock And Tailrace


6 months To record it To repair it if necessary

Supply grease to bearing

6 months

To replace bearing 3 years

Turbine

Bolt connection 1 year To fix them Supply grease to bearing

6 months

To replace bearing 3 years

Winding insulation resistance

6 months To replace generator

Bolt connection 1 year To fix them

Generator

Damage of belt 6 months To replace if necessaryPerformance of load stabilizer

6 months To repair it Load stabilizer

Damage of heaters 6 months To replace if necessaryInlet valve Leakage 1 year To Transformer Leakage of oil 1 month To replace if necessaryTransmission and Distribution line

Approaching branch 1 month To cut it as necessary

10.3.3 Special Inspection

In case of earthquake, flood, heavy rain and accident, operators must stop operation

and inspect facilities.


- 10-9 -

10.4 Recording

Operators must keep a record of the operation and maintenance of the

micro-hydropower plant. Records will provide much help to operators in monitoring

the conduct of the regular or scheduled activities for the operation and maintenance.

It also provides good data in determining the causes of trouble in case of accident.

A sample of operation record and daily patrol check sheet is shown in the next page.

Guidelines for the Construction of Micro Hydro Electric Power Plant Chapter 10

- 10- -

- 10-10 -

Check Sheet Civil Construction

Month : ____________________ Year : _______________

Remarks : ! Fill the column as the actual condition such as : (N) Normal, (B)Bad, (R)Broken

Acknowledge Checker

Chairman Operator

Daily Checking No Description 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

I Dam 1 Construction 2 Stop Log

II Settling basin 1 Construction 2 Screen

III Headrace 1 Construction 2 Stop Log

IV Forebay tank 1 Construction 2 Screen

V Penstock 1 Penstock 2 Foundation

VI Power House 1 Construction 2 Sanitation

VII Tailrace 1 Construction

Damage Note Cause of Damage Repairing Note Repaired by


- 10- -

- 10-11 -

Check Sheet Mechanical and electrical

Month : ____________________ Year : _______________

Remarks: : ! Fill the column as the actual condition such as : (N) Normal, (B)Bad, (R)Broken

!! If there is a fatal damage, repair immediately, or coordinated with IBEKA team Telp. 022-4202045

Acknowledge Checker

Chairman Operator

Daily Checking No Description 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

I Turbine 1 Runner 2 Bearing turbine

3 Plummer Block Bearing

4 Pull Turbine 5 Cover pulley 6 Coupling

II Panel control 1 Meter 2 Lightning rod 3 Ballast Load 4 Main Board

Damage note Cause of Damage Repairing Note Repaired by


- 10- -

- 10-12 -

Check Sheet Distribution Line

Month : ____________________ Year : _______________

Remarks : ! Fill the column as the actual condition such as : (N) Normal, (B)Bad, (R)Broken

!! If there as problem with the distribution facility, repair immediately and fill the damage column

Acknowledge by Checker

Chairman Operator

Daily Checking No Uraian 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

I Transmission 1 Pole 2 Cable 3 Connector 4 Group MCB

II In house installation 1 MCB 2 Installation Cable

Damage Note Cause of Damage Repairing note Repaired by


- 10- -

- 10-13 -

Lubricant & Spareparts

Year : _________________

Notet. : Fill the column with the lubrication date

LOG BOOK Year : __________________

Lubrication based on total operation hour

January February March April May June July August September October November December No

Description

720 1440 2160 2880 3600 4320 5040 5760 6480 7200 7920 8640

A LUBRICATION

1 Bearing Turbine

2 Plummer Block Turbine Bearing

3 Plummer Block Turbine Generator

B SPAREPARTS

1 Bearing

2 Seal

3 Coupling

4 Flat Belt

5 Others

Re-setting


- 10- -

- 10-14 -

Recorder

___________ Operator

Time Operation

Volt Ampere Watt Output Total Date

Start Stop Hour/day

Opening of Guide vane %

Frequency meter (Hz)

R-N(V1) S-N(V2) T-N(V3) A1 A2 A3 V1xA1 V2xA2 V3xA3 Watt Remarks

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Note: Fill the column after installation to the house Calculation of power output = (A1+A2+A3)x220 on condition ballast 0 (zero) volt


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Chapter 11 MANAGEMENT

11.1 Establishment of Organization

Micro-hydropower projects for rural electrification are different from private power

companies, in which all parties concerned that includes the consumers, O&M groups,

community organizations, and Barangay, Local and Central governments, have to

accomplish their roles and responsibilities to ensure sustainable operation.

A sample of organization chart for implementation of micro-hydropower projects is

shown in Attachment-1.

An O & M organization called the Barangay Alternative Power Association (BAPA)

should be established to take care of the operation and management prior to project

implementation. The BAPA should have its by-laws and elected officials duly

recognized by a General Assembly.

11.2 Management System

Background

More than a half of existing micro hydropower plants in rural areas are non-operational

due to various causes of troubles. Most operators do not have appropriate knowledge

and skill on operation and maintenance for micro hydro plants. Usually, budget for

operation and maintenance were not given due importance. As a result, operators

cannot work well for the plant without sufficient salary. Also, they cannot implement

preventive maintenance for the equipment without enough money. This will usually

result to curative maintenance which is more expensive or if not implemented will

result to operational stoppage. Therefore, the causes of problems of micro hydropower

plant are not only due to low quality of facilities and equipment but also insufficient

management practice of concerned organization.

In order to manage the BAPA, rules and regulation that provide objectives, member’s

role and responsibilities, scope of work, etc. should be established before

commissioning the plant. It should also be necessary to stipulate respective

responsibilities in the by-laws of the association, all pertinent rules and regulation that


- 11-2 -

shall be binding and imposed up to the operational life of the power system.

Importantly, training on management should also be conducted.

Establishment and management of organization for the plant are necessary for

long-term operation of a micro hydropower plant. Moreover, it becomes possible to

maintain the organization substantially by monitoring from the outside.

11.3 Reporting and Monitoring

Operational data and maintenance results should be recorded and kept because it will

be used as basis of operators to find out the causes of trouble in the future. Likewise,

record of tariff collection and balance sheet of income and expenditure are essential for

BAPA to manage itself substantially.

If management of BAPA is controlled by few people, sometimes led to falsifying

records to appear that the operation of the organization is in good standing and

diversion of funds to other purpose. As a result, the trouble-shooting of the facilities

will be very difficult due to lack of records and funds. To prevent such situation or get

technical and managing advices, it is advisable to introduce reporting system that

BAPA will report results of operation and maintenance and financial management to

the DOE and the concerned LGU periodically.

On the other hand, the DOE and the concerned LGU should conduct monitoring that

they will visit sites periodically, and check the condition of operation and maintenance

and management of BAPA, and then give BAPA technical and administrative advices

if necessary.

Periodic report on operation and maintenance of the micro-hydro system is necessary

as basis for identification of future repairs.

11.4 Decision-Making System

The General Assembly is the final approval of all decisions made which are not

stipulated in the By-Laws of the organization. The proposal should be approved by the


- 11-3 -

Board of Directors (BOD) before it will be presented to the General Assembly.

11.5 Accounting System

Accounting System consists of;

Tariff System,

Electricity Charge Collection System,

Expenditures

Procedures on Pay Out,

11.6 Roles and Responsibilities of BAPA

BAPA (Barangay (Village) Alternative Power Association) carries out following work

as an operation and maintenance organization, consulting with related agencies:

Formulate and implement rules and regulations of the organization.

Collect electricity tariff from consumers, and manage income and expenditure

Operate and maintain a power plant, and the supply electricity to consumers

efficiently and safely. Repair or replace facilities and equipment if necessary.

Instruct consumers on guideline of safe and efficient usage of electricity.

Report result of operation and maintenance of the plant and financial

management to DOE and related LGU periodically.

11.6.1 BAPA Officials

1) Chair Person:

Chair person is the Head of the BAPA Organization. His duties are:

Comprehensive management of generation facilities and users whether

they are using electricity according to the rules and/or the regulations.

2) Board of Directors:

Board of Directors may consist of several persons, and their duties are:

Giving the appropriate advice to the Head of the BAPA when requested

by the Head. In any time, they can investigate the status of the overall


- 11-4 -

management, status of use of electricity by users, facilities’ status of the

Micro-Hydro Power Plant itself, and other necessary matters, if they

judge to need to do it.

3) Vice Chairperson:

Vice Chairperson assists the chair person and act as the Head of the

BAPA in the absence of the chair person.

4) Secretary:

On the smooth performance of the BAPA, several secretarial works may

be needed.

5) Accountant:

Duties of the Accountant are:

Collection of electricity charge based on the agreed tariff system

and book-keeping.

The electricity charge may be collected by means of the people

coming to the accountant periodically to pay their electricity

charges and then the accountant enters up their payments with

their names in an account book and keeps it carefully.

Cash management.

The cash as a revenue due to collection of electricity charge

should be managed by the accountant carefully. To use banking

system is one of ways.

6) Operators and Technicians:

At least, 3 operators may be needed.

Duties of the Operator(s) are:

Daily operation of micro-hydro power facilities.

Periodical check of all the facilities.

Uncomplicated maintenance for the facilities.

Judging required maintenance with cost to procure necessary

spare-parts and/or tools to be needed for maintenance.

Report the required maintenance with cost to procure necessary

spare-parts and/or tools for maintenance to the Chair Person.


- 11-5 -

11.6.2 Consumers

Consumers must have the following responsibilities:

Pay electricity tariff

Use electricity safely and efficiently.

11.6.3 Local Government Unit (LGU)

Concerned LGU shall have the following responsibilities:

Implement a micro hydro project.

Supervise management of BAPA

Conduct training of BAPA staff

Propose appropriate livelihood projects that utilize electricity.

11.6.4 Department of Energy (DOE)

As a lead agency in rural electrification, the DOE shall have the following

responsibilities:

Coordinate with NEA thru RECs to organize BAPA

Conduct monitoring of micro hydropower plant periodically.

Advise on technical and management aspects to insure sustainability

of the system.

11.7 Training

BAPA staff including operators must have enough knowledge and skill on operation,

maintenance and management of BAPA. Therefore, they should receive training before

the operation of a power plant.

Training components are as follows:

Operation and maintenance of a micro hydropower plant

Maintenance of transmission and distribution line

House wiring installation and its maintenance

Organization management including documentation

Financial management

Concerned LGU or proponent should have a responsibility to conduct these training


- 11-6 -

before commissioning of the plant. In case of change of staff, skilled staff of BAPA

should train new staff.

11.8 Collection of Electricity Charge and Financial Management

11.8.1 Tariff Setting

Income from electricity tariff is an important source of fund to operate and maintain

a micro hydro power plant. Therefore, tariff rate should be set considering not only

salary of BAPA staff but also expenses for purchasing spare parts, repair and

replacement of equipment in the future. However, most of residents in rural areas

electrified by micro hydro plants are categorized into under poverty line. Hence,

tariff rate should be set considering solvency of residents for them to cope up.

Taking into account current expenditure for energy (kerosene and battery), assumed

electricity consumption of local people and tariff rate of RECs, four to five pesos

per kilowatts is reasonable to set tariff rate for micro hydro at the moment, as of

2001.

BAPA should decide which way is adapted in the rules and regulations of the BAPA.

It is either the tariff rate is based on consumption, fixed rate per bulb-wattage

installed. For poorer barangays, they usually adapt fixed rate, but it should be

higher than the consumption based rate.

11.8.2 Tariff Collection

There are two ways of bill collection. One way is that bill collectors visit all houses

in the supply area and then collect money from them one by one. Another way is

that representative of a district collect money from consumers within each district

and then he/she pay collected money to BAPA.

Since tariff collection is important income for operation and maintenance of plants

as mentioned above, bill collection should be done accurately. In case of

non-payment of bill, they should sometimes stop supplying electricity to

non-paying consumers.


- 11-7 -

It is necessary that operators sometimes carry out patrol along distribution lines in

order to avoid illegal tapping of electricity.

11.8.3 Financial Management

Since BAPA is required for a stable supply of electricity to consumers for long

period, BAPA has to operate and maintain a power plant in good condition.

Therefore, BAPA has to administer the collected money and put aside funds for

future maintenance. We have to understand that even if the equipment is of high

quality, troubles may set in during its long-term operation, and then replacement of

spare parts will certainly be required within the years of operation.

An accounting system should be developed including a tariff system, collection of

electricity charges according to the tariff system, book keeping, cash management

method. Training on this aspect should also be conducted.

BAPA has an obligation to make balance sheets of income and expenditure and then

to report periodically. BAPA has to avoid that collected money is used for other

purposes.

Department of Energy

Energy Complex Merritt Road, Fort Bonifacio, Taguig City, Metro Manila

TEL: 840-14-01 to 21 FAX: 840-18-17

１

Department of Energy

Energy Complex Merritt Road, Fort Bonifacio, Taguig City, Metro Manila

TEL: 479-2900 FAX: 840-1817

Documents

Manuals and Guidelines for Micro-hydropower …gwweb.jica.go.jp/km/FSubject0901.nsf/8f7bda8fea534ade...Manuals and Guidelines for Micro-hydropower Development in Rural Electrification