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Summer Internship Report
On
Analysis of Forecasting and Scheduling of Wind Power for Grid
Integration in U.S.A. and Europe alongwith the comparison with the
Indian Power Market.
Under the guidance of
Mr. Amit Mittal (AGM)
ICRA Management Consulting Services Ltd
Submitted by
Kriti Walia
Roll No. 39, Batch 2012-14
MBA (POWER MANAGEMENT)
NATIONAL POWER TRAINING INSTITUTE
Affiliated to
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
2 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
TRAINING COMPLETION CERTIFICATE
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
3 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
ACKNOWLEDGEMENT
The projects done by me under this internship program would not have been completed, if not for
the active help and guidance of various people.
I express my sincere thanks to Mr. Amit Mittal (AGM), IMaCS and Mr. Sunil Varma Marri
(Head – Energy Sector), IMaCS for giving me a great opportunity to work in such a dynamic
organization and for guiding me in all stages of the project. I am thankful to Mr. Santosh Singh
and Mr. Himanshu Chawla, IMaCS for their guidance and support. I have a deep sense of
gratitude and respect for the entire staff of IMaCS for sharing their knowledge and for assisting
me.
I am indebted to Mr. S K Choudhary (Principal Director), CAMPS and the entire faculty in
CAMPS for arranging the internship and for the assistance provided in various stages of
internship. As a student, I thank you for the knowledge and values which you have imparted to
me. As a citizen, I thank you for the service you are rendering to this Nation.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
4 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
DECLARATION
I, Kriti Walia, Roll no. 39 / Semester III / Class of 2010-12 of the MBA (Power
Management) programme of the National Power Training Institute, Faridabad hereby
declare that the Summer Training Report entitled
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in U.S.A.
and Europe alongwith the comparison with the Indian Power Market.
is an original work and the same has not been submitted to any other Institute for the award
of any other degree.
A Seminar presentation of the Training Report was made on ………………….. and the
suggestions as approved by the faculty were duly incorporated.
Presentation In charge Signature of the Candidate
(Faculty)
Countersigned
Director/Principal of the Institute
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
5 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Contents
Abbreviations ........................................................................................................................................ 7
Organization Profile ............................................................................................................................... 8
IMaCS - An introduction ....................................................................................................................... 8
IMaCS Consulting Services in the Energy Sector ............................................................................... 10
Project
1. Executive Summary ............................................................................................................... 13
2. Objective of the Project ......................................................................................................... 17
3. Significance of Project .......................................................................................................... 18
4. Research Methodology ........................................................................................................... 19
5. Introduction …………............................................................................................................ 20
6. Development of wind power forecasting in abroad ................................................................ 24
7. Analysis of International Power markets …………………………………………………… 25
7.1 Europe ………………………………………………………………………………………………… 25
7.2 U.S.A. …………………………………………………………………………………………………. 45
7.3 India ………………………………………………………………………………………………… 60
8. Solutions for wind integration in India ……………………………………………………………….. 71
9. Conclusion ……………………………………………………………………………………………. 72
10. References ……………………………………………………………………………………………. 72
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
6 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
ABBREVIATIONS
AC Alternating Current
DSM Demand Side Management
GW Gigawatt
GWh Gigawatt hour
HVAC High voltage AC
ISO Independent System Operator
MVAR Mega Volt Ampere Reactive
MW Megawatt
MWh Megawatt hour
NREL National Renewable Energy Laboratory (Boulder, USA)
NRMSE Normalised Root Mean Square Error
NWP Numerical Weather Prediction
PIRP Participating in Intermittent Resource Programme
RMSE Root Mean Square Error
SCADA Supervisory Control and Data Acquisition
TSO Transmission System Operator
TW Terawatt
TWh Terawatt hour
VPP Virtual Power Plant
VSC Voltage Source Converter
WEPP Wind Energy Power Plant
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
7 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
LIST OF TABLES AND FIGURES
Fig.1 Overview of operating frequency limits imposed by grid codes
Fig.2 European Market Structure
Fig. 3 NORDPOOL market structure
Fig. 4 Integration measures for Large Scale Wind Power in Denmark
Fig.5 The interconnectors to the Continental and the Nordic synchronous areas
Fig.6 Time divisions of the Danish electricity market
Fig 7 A. Price setting of the market (no wind)
Fig 7B. Price setting of the market (wind)
Table 1: Structure of Wind Farm
Table 2: Cumulative Wind Generation Capacity as on Dec 2011
Table 3: Classification Of Wind Power Forecast Methods According To Time Scales Relevant For Power
Systems Operation
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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8 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Organization Profile
IMaCS - An introduction
ICRA Management Consulting Services Limited (IMaCS) is a multi-line management
consulting firm headquartered in India. It has an established track record of 17 years in
management and development consulting across various sectors and countries. IMaCS has
completed more than 1200 consulting assignments with about 600 clients and has worked in
over 40 countries across the globe. IMaCS is a wholly-owned subsidiary of ICRA Limited
(ICRA), one of India‟s leading credit rating agencies. IMaCS operated as an independent
division of ICRA till March 2005, when it was de-merged from ICRA and became a
standalone company in its present form.
Launched in 1991, ICRA has been set up by a number of prominent Indian financial
institutions, banks, and insurance companies. ICRA has subsidiaries in Indonesia and Sri
Lanka. Group ICRA comprises four businesses, namely, Credit Rating, Management
Consulting, Information Technology, and Outsourcing, offered by four different companies
comprising ICRA and its three subsidiaries, namely, IMaCS, ICRA Techno Analytics Ltd.
(ICTEAS) and ICRA Online Limited. ICRA is listed on the National Stock Exchange and the
Bombay Stock Exchange in Mumbai, India.
Group ICRA
IMaCS began as a firm operating in India and has since worked in several parts of the world
on its own and through strategic partners. The clientele includes banks & financial service
companies, private corporates (manufacturing and service organizations), governments,
government-owned organizations, financial investors and fund managers, regulators, and
multilateral agencies. The New York based subsidiary, IMaCS Virtus Global Partners, Inc.
offers Strategy and Transactional Advisory services to companies in North America and in
India seeking to operate in the Indo-American corridor.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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9 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
IMaCS has six practice areas grouped under Strategy, Risk Management, Process Consulting,
Transaction Advisory, Policy Advisory, and Capacity Building
IMaCS’s Matrix of Service Offering
Through the process of carrying out several assignments over the past 17 years, IMaCS has
accumulated considerable analytical and consulting expertise, backed by the following
organisational capabilities:
An extensive and organised database on several sectors.
Knowledge of key factors of success in different projects and program.
An ability to research emerging global trends, both in specific countries as well as in
different sectors, based on primary and secondary data.
Performance benchmarking
Quantitative and financial modelling
Ability to identify the various types of risks and suggest appropriate strategies to mitigate
the same
Ability to work in different geographies on its own and through affiliate partners
IMaCS’ Consulting Services in the Energy Sector
The Energy Group of IMaCS is a leading provider of policy and regulatory consulting,
transaction advisory services to all stakeholders in the power sector. The Energy Group
focuses on strategy, policy and transactional issues related to the Electricity, Renewable
energy, and the Oil and Gas sectors. The Group has garnered significant expertise in the
restructuring and reform process in the electricity sector by having been associated with
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
10 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
multiple entities such as the government, regulators, state owned and private power
companies since the beginning of the reforms process in the sector.
IMaCS‟ services in the energy domain encompass regulatory assistance to utilities and
regulatory commissions, restructuring and privatization formulating strategies and business
plans for utilities, conducting market assessment studies for investors/utilities, providing
assistance to developers/project appraisal/project risk assessment, and investment and
transaction assistance. IMaCS has also assisted Indian and international business groups in
formulating strategies to enter the energy business. IMaCS has completed several projects in
the renewable sector covering diverse technologies such as wind, hydro, co-generation, and
biomass, and has also worked on policy level assignments.
IMaCS offers its services in the power sector along four functional areas as shown below.
IMaCS’s Offerings in the Power Sector
Offerings in Reform, Regulation & Policy
Power sector reforms and restructuring
Institutional development and capacity building
Designing/drafting regulatory frameworks /rules
Corporatization & Privatization Advisory
Pricing /costing models
Assistance in tariff setting process to regulators /utilities and bulk consumers
Demand side management strategies
Creating competitive wholesale and retail level markets
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
11 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Performance improvement - Benchmarking, Setting multi-year tariff
Formulating policies for PPP/PSP & power trading
Universal service/coverage - Rural electrification
Renewable & Hydro sector development
Designing & developing energy markets/exchanges
Designing and implementing regulatory information systems
Offerings in Risk Management
Independent assessment of project risks
Project appraisal for lenders and developers
Assessment of project sponsors and Joint Venture partners
Credit risk assessment for off-taker entities – utilities/ electricity boards & bulk consumers
Market and fuel risk management solutions
Structuring solutions to address payment risk and other risks - Payment Security
Mechanisms
Enterprise risk management solutions for IPPs, trading companies
Equity Investment Appraisal
Offerings in Transaction & Project Advisory
Feasibility studies – Techno-economic and financial feasibility, Economic/Social Cost
Benefit Analysis, and Environmental Impact Analysis
Structuring of investments – Risk assessment, allocation of risks, identification
Bid process management – Drafting & review of concessions/contractual agreements
Preparation/Review of bid documents – RFQ/RFP & evaluation of bids, negotiation and
selection of bidder(s)
Drafting & negotiation of Power Purchase Agreements & Fuel Supply Agreements
EPC bid-process management for Power project developers
Project Appraisal with a focus on lenders' perspectives for bankability verification
Project/Capital structuring, financial engineering and securitisation for power projects
Equity mobilisation for power projects from private equity investors
Assistance in financial closure of power projects.
Due diligence and business valuation
Assistance to utilities/power projects in financial/debt restructuring
Acquisition/Divestment Advisory for power projects
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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12 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Offerings in Strategy & Operations
Energy Market Analysis
Demand forecasts – time series & econometric modelling
Market assessment & competitiveness studies for IPPs & power equipment manufacturers
Business Plans for utilities, power projects and captive power projects
Market entry strategy formulation for strategic investors
Improving regulatory preparedness of utilities
Fuel procurement strategies
Expansion/diversification/backward integration strategy
Cost/Loss reduction and Process improvements for utilities
Performance measurement and benchmarking for utilities
Organisational restructuring and Manpower rationalisation
Clients
IMaCS has advised/assisted almost all types of entities in the Energy Sector such as,
Leading international Project Developers and Domestic Independent Power Producers
(IPPs)
Lenders – Multi-lateral agencies, International / Domestic Financial Institutions and Banks
Equity investors
Governments and Government agencies
Public Sector Enterprises
Private sector entities
Utilities operating in power sector
Renewable Energy Development Agencies
Industry Associations
Regulatory Bodies
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
13 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Fertiliser Companies
EPC Contractors and Manufacturers
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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1. EXECUTIVE SUMMARY
The possibilities and detailed strategies for managing variable-output wind power vary
between national and regional power systems. Like any other form of generation, wind power
will have an impact on power system reserves. It will also contribute to a reduction in fuel
usage and emissions. The impact of wind power depends mostly on the wind power
penetration level, but also depends on the power system size, generation capacity mix, the
degree of interconnection to neighbouring systems and load variations. Wind farms have the
inherent advantage over conventional power plants of being smaller in total output capacity.
On the wind farm level, their power output variation is always smaller than, for example, the
variation caused by an outage of a conventional plant. On regional aggregated level, wind
power variations are smoothed and the occurrences of zero wind power are rare.
Accurate methods for short-term forecasting of wind power are widely available as there is a
whole range of commercial tools and services in this area, covering a wide range of
applications and customized implementation. On an annual basis, reducing the forecast
horizon from day-ahead to a few hours ahead reduces the required balancing energy due to
prediction errors by 50%. Comprehensive national studies have focused on determining the
additional balancing costs as a function of increasing wind penetration in the national power
system (Nordic region, Germany, UK, Ireland, Spain). The requirements for Grid codes
depend on the specific characteristics of each power system and the protection employed and
they deviate significantly from each other. More demanding appear to be the requirements of
the German, UK, Nordic, Danish, Belgian, Hydro-Quebec, Swedish and New Zealand grid
codes, which stipulate that wind farms must remain connected during voltage dips down to
0%. The business of the Nordic power exchange is to provide market places for trading in
physical and financial contracts in the Nordic countries (Finland, Sweden, Denmark and
Norway). Its physical market accounts for over 60 per cent of the total value of the Nordic
region’s power consumption.
Despite the differences in assumptions, optimization criteria and system characteristics, the
studies arrive at similar results. There is a gradual increase of the additional balancing costs
with wind power penetration. Because of the positive effect of geographical smoothing,
results from these studies show that power systems in large geographical areas can integrate
wind power at lower cost. Likewise, good interconnection to neighbouring systems reduces
balancing costs. Both the allocation and the use of reserves cause extra system costs. This
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
15 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
means that only the increased use of dedicated reserves, or increased part-load plant
requirement, will cause extra costs. According to several national studies made so far, there is
no need for additional conventional plant and that extra reserve needs for wind power can be
obtained from the existing conventional power plants. Estimates regarding the costs of
increase in secondary load following reserves suggest €1–3/MWh (of wind) for a wind power
penetration of 10% of gross consumption and €2-4/MWh for higher penetration levels. The
costs are quite sensitive to the accuracy of wind power forecasting, as well as the practice of
applying forecasts in the market rules.
My observations and suggestions for implementation in India after the work done by me at
IMaCs are as follows:
Wind energy generators are mandated to forecast the wind generation,
since wind forecasting software packages are available in the market.
The philosophy of limited applicability of UI charges to Wind generators
is that it is seen that they can forecast generation of wind energy with an
accuracy of at least 70%. Therefore, within the band of +/-30% variation
from the forecast, they should not be subjected to UI charges.
However, for variation more than that, they are liable to be included in
the UI mechanism, beyond this limit.
The UI mechanism is used only in India. It has been introduced in South
Africa only last year. It is suggested that penalty mechanism other than
UI charges must be adopted in India.
The wind power is forecasted in 15minute time block (96 time blocks in a
day) in India. Internationally, the wind power is forecasted on an hourly
basis. An hourly forecast system must be used in India.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
16 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
*the total duration of these operating conditions must not exceed 10hours/year
Fig.1 Overview of operating frequency limits imposed by grid codes
ABSTRACT
With the world in almost permanent energy crisis due to the pressure of
economic development, wind power is nowadays one of the predominant
alternative sources of energy. The experience in advanced wind power countries
indicates that wind power forecasting (WPF) technology is one of the effective
measures to mitigate peak-load regulation pressure, reduce reserve capacity and
increase wind power accommodation capacity for power grids. Recently, the
leading countries in wind power in Europe and the United States have already
established impeccable management mechanism in WPF, and their forecast is
performed both in wind farm side and dispatching facility side.
This report, combining the international experience and national situation,
studies on the tailor-made wind power forecasting and scheduling system
framework and implementation plan in India.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
17 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
2. OBJECTIVE OF THE PROJECT
This Project has analyzed the effect of wind power on the power system and analysis of the
business model followed by IPP’s of wind power in USA. The major issues of wind power
integration are related to: changed approaches in operation of the power system, connection
requirements for wind power plants to maintain a stable and reliable supply, extension and
modification of the grid infrastructure, and influence of wind power on system adequacy and
the security of supply. Thus there is huge opportunity available in the Sector and the main
aim of the project is to identify the opportunities available in the Sector.
The objectives of the project are as follows:
Analysis and comparison of scheduling and forecasting provisions in various
countries.
Analysis of wind power forecasting technologies present and their benefits
Identification of balancing requirements for the power system.
Identification of various storage options.
Analysis of the IEGC requirements related to wind power integration.
Study of electricity markets of U.S.A. and Europe
Identification of business opportunities available in the sector.
Suggestions for implementation of efficient grid integration of Wind Power.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
18 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
3. SIGNIFICANCE OF THE PROJECT
Wind power is continuous growing in the world and acting as mainstream power suppliers in
many countries instead of it is viewed as an intermittent source of energy. This project
analysed the different Balancing, Storage, Grid code requirements, Forecasting methods &
approaches for making wind power as a firm energy source. Also the business model
followed by IPP’s in USA makes us understand the difference between Indian model and
USA model.
This project is important in a way to study the future opportunities available in the Wind
power sector.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
19 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
4. RESEARCH METHODOLOGY
The report has been compiled on the basis of secondary data sources. Data on integration
cost, balancing, storage technologies etc. have been collected from the information available
on the internet validated from various recognized websites like FERC, NREL, DOE, UWIG,
CAISO, MISO, IEA, AWEA, GWEA, CWET, EWEA & many others.
Steps followed for the project work are as under:
Selection of the project title
Selecting the IPP’s for the purpose of study and analysis
Downloading of all available information of all the IPP’s, ISO, TSO for analysis
Understanding the business model & legalisations of different countries.
Thorough study of all information available from various sources to understand the
wind
power sector.
Scrutinizing the data & Collecting the relevant data from the available documents and
literatures on Internet
Arranging the data year wise in a lucid manner
Comparison of data
Drawing of inferences and conclusions
Giving suggestions & recommendations
Drafting of report
Submission of report to the mentor for review, suggestions and modifications
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
20 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
5. INTRODUCTION
5.1 Wind Energy
Air in the motion is called wind. Wind is global phenomenon occurring on the
earth’s surface due to unequal heating of various parts of the earth’s surface by
the sun. Wind speed and direction vary in the short and long term. There is a
variation on minute to minute basis. Wind is affected by the terrain and by
height above the ground. Wind speed generally increases with the height above
the ground as moving wind moving across the earth’s surface encounters
friction caused by the turbulent flow over and around the mountains, hills, trees,
buildings etc. The Earth is unevenly heated by the sun, such that the poles
receive less energy from the sun than the equator; along with this, dry land heats
up (and cools down) more quickly than the seas do. The differential heating
drives a global atmospheric convection system reaching from the Earth's surface
to the stratosphere which acts as a virtual ceiling. Most of the energy stored in
these wind movements can be found at high altitudes where continuous wind
speeds of over 160 km/h (100 mph) occur.
5.2 Wind Power Generation
Generation of electricity has emerged as the most important application of wind
energy worldwide. The concept is simple: flowing wind rotates the blades of a
turbine, and causes electricity to be produced in generator unit. The blades and
generator(housed in a unit called ‘nacelle’) are mounted at the top of a tower.
Wind turbines generally have three rotor blades, which rotate with wind flow
and are coupled to a generator either directly or through a gear box. The rotor
blades rotate around a horizontal hub connected to a generator, which is located
inside the nacelle. The nacelle also houses other electrical components and the
yaw mechanism, which turns the turbine so that it faces the wind.
Sensors are used to monitor wind direction and the tower head is turned to line
up with the wind. The power produced by the generator is controlled
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
21 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
automatically as wind speeds vary. The rotor diameters vary from 30 metres (m)
to about 90 m, whereas the towers, on which the wind electric generators
(WEGs) are mounted, range in height from 25 to 80 m. The power generated by
wind turbines is conditioned properly so as to feed the local grid. The unit
capacities of WEGs presently range from 225 kilowatt (kW) to 2 megawatt
(MW), and they can operate in wind speeds ranging between 2.5 m/s (metres
per second) and 25 m/s.
5.3 Wind Power Grid Integration
Grid Integration of existing off-grid DRE projects will considerably increase
their viability and sustainability and further have positive implications for
enhancing electricity access. Since the centralized grid acts like a large battery,
feeding electricity into the grid will ensure lowering of the costs of DRE
projects by improving their Capacity Utilization Factors (CUFs).WPF
technology is widely developed and applied in the European countries over the
past about 20 years. They actively develop and construct WPF systems and
bring wind power into electricity market and grid dispatching system. The
experience in advanced wind power countries indicates that wind power
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
22 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
forecasting (WPF) technology is one of the effective measures to mitigate peak-
load regulation pressure, reduce reserve capacity and increase wind power
accommodation capacity for power grids. Meanwhile, this technology also
plays an important role in instructing maintenance plan of wind farms,
increasing utilization of wind energy and improving economical benefit of wind
farms.
Recently, in most of the advanced wind power countries WPF systems are
installed in both sides of wind farms and dispatching facilities and related
management systems are established. WPF is a mandatory requirement in many
countries and utilities, such as in Spain, Ireland, and PNM and ERCOT
(Electrical Reliability Council of Texas) in the United States; California ISO
(CAISO) stipulates that the wind farms in its jurisdiction have free choice of
WPF system providers rather than those listed by CAISO, although wider
forecast error is allowed for the listed WPF providers for grid integration.
Priority for grid connection is granted to wind farms in Denmark and Germany
based on their Renewable Energy Law. But grid operators do not set the liability
for wind farms to forecast their generated power in Grid Integration Agreement
and Electricity Purchase Agreement.
Countries such as Denmark, Germany and the United States have been able to
meet their strict forecasting guidelines through the availability of updated
meteorological information and employing various technical measures like
energy assessments, use of a sufficient number of onsite meteorological masts,
wind flow modelling etc. However, these technical measures are best suited to
geographies with consistent wind patterns, unlike India. These countries also
have the benefit of professional forecasting agencies like Energy and Me-teo
GmbH (Previento) and AWS Truewind (eWind) which is not the case in India.
As of March 2012, the majority of Indian wind farm developers were in the
process of acquiring and setting up the necessary tools for forecasting and only
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
U.S.A. and Europe alongwith the comparison with the Indian Power Market. 2013
23 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
a few farm developers like Gamesa and GFL in Gujarat have commenced
forecasting and providing schedules to the SLDC on a trial basis. Wind
forecasting is further complicated by the SLDCs inability to evaluate forecasts
and schedules provided by wind energy producers due to inadequate metering
facilities. According to industry insiders, the absence of reliable meteorological
data, historical wind pattern data, sophisticated wind prediction technology
coupled with inconsistent wind flow patterns prevalent in India, means that the
imposition of UI charges will have a crippling effect on financing of wind
energy projects as well as project profitability.
Table 1: Structure of Wind Farm
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5.4 Importance of Wind Power Forecasting
6. Development Status of the Wind Power Forecasting Abroad
Table2: Cumulative Wind Generation Capacity as on Dec 2011
Nowadays the wind power prediction system have been widely applied in
Denmark, Germany, Spain, United States and other developed countries. It had
• Better forecasts mean lower operating reserves
• Lower operating reserves mean lower operating costs
• Avoid penalties for bad forecasts
Economics
• Situational awareness for operators
• System positioning for ramping events
• Preparation for extreme events
Reliability
• Understand need for and provide incentives for the right market
• Products with high VG penetration
• Align market rules with forecasting capabilities
Market Operation
62733
46919
29060 21674
16084
6800 6747 6540 5265 4083
32446
0
10000
20000
30000
40000
50000
60000
70000
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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25 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
become an important support system of the wind power optimal dispatch.
Recently, in most of the advanced wind power countries WPF systems are
installed in both sides of wind farms and dispatching facilities and related
management systems are established.
The wind power prediction system is classified into 0-4 hours ultra-short term
forecasting and 0-48 hours short term forecasting. With the development of
wind power industry, moreover, the effective forecasting is playing a more and
more important role in the economic operation, its benefit to utilities is also
increased with the improvement of forecasting accuracy. Although these
methods obtained definite forecasting effect, the forecasting precision and
stability still need to improve.
7. Analysis of International Experience
7.1 EUROPE
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
82,232 92,518 1,01,773 1,09,815 1,18,248 1,27,324 1,35,590 1,43,790 1,52,905 1,61,165 1,70,054 2,590 3,724
5,820 9,146
12,357 15,606
20,423 25,827
31,104 36,790
43,324
Cumulative wind power installations in the EU(MW)
Onshore Offshore
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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The net output of all wind turbines on the system or large groups of wind farms
are considered. Wind power has to be considered relative to the overall demand
variability and the variability and intermittency of other power generators. Thus,
wind can be harnessed to provide reliable electricity even though the wind is not
available 100% of the time at one particular site.
In terms of overall power supply, it is largely unimportant what happens when
the wind stops blowing at a single wind turbine or wind farm site.
The Forecast performance varies with many factors:
a. Forecast time horizon especially for short term
b. Amount and diversity of Regional aggregation
c. Quality of generation and meteorological data from the plant
d. Distributions of wind speeds relative to the power curve
e. Type of wind and weather regime
f. Shape of the plant-scale power curve
g. Amount of variability in the wind resource
3.8
74
43
8.5
16.1
80
2.5
20.6
11.6
1.7 1.6 1.6
66
28 27
20
10
2 0
10
20
30
40
50
60
70
80
90
Wind Power Capacity Penetrations in Various European Countries
Reference Load(GW)
Wind Power Capacity (GW)
Capacity Penetration
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h. Sensitivity of a forecast to initialization error
These factors make casual comparisons of forecast performance very
difficult and lead to misconceptions.
5-60 min 1-6 hours Day ahead Seasonal
long-term
Uses Regulation
Real-time
despatch
decisions
Load
following, unit
commitment
for next
operating hour
Unit
commitment and
scheduling,
market trading
Resource
planning
contingency
analysis
Phenomena Turbulent
mixing
transitions
Fronts, sea
breezes,
mountain-
valley
circulations
Low and high
pressure areas,
storm systems
Climate
oscillations,
global
warming
Methods Largely
statistical,
driven by recent
measurements
Combination of
statistical and
NWP models
Mainly NWP
with corrections
for systematic
bias
Based
largely on
analysis of
cyclical
patterns
Table 3: Classification Of Wind Power Forecast Methods According To Time Scales Relevant For
Power Systems Operation
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Fig.2 European Market Structure
Fig. 3 NORDPOOL market structure
Nord Pool launched its day-ahead market in 1993 and its adjustment market in
March 1999. 216 participants were allowed to trade on the spot market in
December 2001. Nord Pool Spot organises the market place which comprises
the Elspot and Elbas products. Elspot is the common Nordic market for trading
physical electricity contracts with next-day supply. Elbas is a physical balance
WHOLESALE MARKET
•Here bulk electricity is sold and purchased between suppliers, generators, non-physical traders and large end users
RETAIL MARKET
•Here electricity is finally sold to the end consumer
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adjustment market for Sweden, Finland and Denmark. Both the Elspot and
Elbas market also include the KONTEK area in Germany.
Elspot (day-ahead market)
The Elspot day-ahead power market is a market with physical delivery. The
products traded are power contracts with one hour duration and block bids. The
hourly contracts cover all 24 hours of the following day. Currently, there are
five block periods approved for trading in the day-ahead market:
• Block 1 – 1:00-7:00;
• Block 2 – 8:00-18:00;
• Block 3 – 19:00-24:00;
• Block 4 – 1:00-24:00;
• Block 5 – 8:00-24:00.
Prices at Elspot are determined through auction trade for each delivery hour.
Each sale/purchase bid is a sequence of price/volume pairs for each specified
hour with a minimum size of 0.1 MWh/h.
Bids are submitted to the marketplace either electronically via Internet, or by
fax on special bid forms, before noon (deadline). Purchases are designated as
positive numbers, sales as negative numbers.
Elbas (Adjustment Market)
The adjustment market “Elbas” aims to improve the balance of physical
contracts of the participants.The trading products are one-hour physical delivery
contracts, which can be traded up to 1 hour before delivery. This market is
currently limited to Sweden and Finland, but the inclusion of further Nordic
countries is under consideration.
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Elbas offers continuous trading all around the clock and every day. The trading
session for a specific day starts after the publication of the results of Elspot for
this day. Bids can be submitted electronically or by phone (helpdesk). Their
minimum size is 1 MWh and prices are quoted in Euro with a minimum tick
size of 0.1 Euro.
Danish Electricity Market
Denmark is the connecting node of the Nordpool, the Nordic electricity market
and the European electricity market, but mainly participates in the Nordpool
because of limitation of the electric transmission capacity in different countries.
Nordpool is composed by Denmark, Norway, Sweden and Finland. Energinet is
the power system, grid and electricity market operator of Denmark.
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Fig.4 Integration measures for Large Scale Wind Power in Denmark
Denmark is the only country in Europe that belongs to two synchronous areas.
For historical reasons Western Denmark belongs to the Continental
synchronous area and Eastern Denmark belongs to the Nordic synchronous
area. Both the Continental synchronous and the Nordic synchronous areas
operate at 50 Hz AC, but the areas are not synchronized. As a result, the
interconnector between Western Denmark and Germany is AC, and similarly
the interconnector between Eastern Denmark and Sweden is also AC. On the
other hand, the interconnectors between the Nordic synchronous area and the
Continental synchronous are DC, including the interconnector between Western
Denmark and Eastern Denmark. Due to the historical background, Western
Denmark and Eastern Denmark are also separate electricity market price areas.
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Fig.5 The interconnectors to the
Continental and the Nordic synchronous areas
With the liberalisation of the power sector in 2000, the unsuccessful attempt to
introduce a green certificate system to compliment the liberalised market and a
change of government policy for wind power remuneration in 2002 the
deployment of wind turbines met an abrupt halt. This has been the case until
2008, when deployment of turbines once again begun to gather momentum in
Denmark due to the introduction of a new feed-in tariff.
The Nordpool electricity market includes future market, day ahead market (spot
market) and intraday market. All markets are hourly markets. Additionally, the
TSOs operate reserve and regulating markets. In the reserve market, the
reserves for the coming day are purchased at 9:30. The Day ahead market is set
at 12:00. Intraday market starts at 14:00 the day before operating day until one
hour before delivery hour. Regulating market is continuously operated from
0:00 to 24:00.
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Fig.6 Time divisions of the Danish electricity market
Pricing mechanism of the market
1. Reserve market
In reserve market, the single buyer is the TSO. The sellers are all of the power
plants which can offer the reserved capacity. The reserved capacity is mainly
used to guarantee safe and stable operation of the systems for any emergency.
The prices for a reserved capacity are low in reserve market in Denmark but the
price for the activated energy can be very high. Participants submit bids to the
market. No matter whether the reserved capacity is used in the day, TSO need to
pay for it. The payment which is used for the reserved capacity comes from the
income of the electricity rates.
2. Day ahead market (spot market)
In day ahead market, all the power plants and the demanders are the market
participants. The market price is determined by marginal pricing of the supply
and the demand. The day ahead market is mainly used to ensure the 24 hours
generation plan and the electricity prices of the next day, according to the
bidding results. The red and green curves are the demand and supply curves
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respectively. The cross point of the curves is the electricity price of that hour.
The different productions follow the same price.
Fig 7 A. Price setting of the market (no wind)
Fig 7B. Price setting of the market (wind)
There are big bidding differences in market among different productions.
Because of the low operation costs and the governmental subsidy, the submitted
bid of wind power was lower than other powers. The output of the wind power
obviously influences the price of that hour. The more the wind power outputs,
the lower the market price will be. When the outputs of the wind power are
larger enough, to sell the wind power successfully, the bidding could be
negative electricity price. Even so, the wind power plants can earn the profit due
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to the balance of the subsidy. In the market of negative electricity price, the
wind power plants supply the most of the electric power. Parts of the thermal
power plants sell the electric power to avoid the loss of turn off operations.
3. Intraday market
The intraday market is the trade that takes place during the day of operation
when the day-ahead market is closed. After the day-ahead market is closed, the
day ahead plans would be adjusted according to the real condition due to the
faults of hydroelectric generating units, faults of transmission line, forecasting
errors of the wind power and so on.
The intraday market trades hourly power from 14:00 the day before delivery
day until one hour before delivery hour. Market participants can use the
intraday market to balance their positions. In general, the later the generation
plan adjusts, the more the cost goes up. For example, when the wind power
plants find the output of the wind power can not satisfy the generation plan of
the day ahead market in the next hour according to the updating forecasting
results, they need to buy the electricity gap from other power plants. The
electricity price is usually higher than the price of the day ahead market; when
the wind power plants find the output of the wind power is more than the
generation plan of the day ahead market, they can also sell the extra power. But
the electricity price is much less than the price of the day ahead market.
4. Regulating market (Real time market) Regulating market is from 0:00 to 24:00. In order to supervise the generation
plan and guarantee the stable operation of the systems, TSO adjust the outputs
of the power plants in regulating market. The regulating market is administered
by TSO. To make a balance between demand and production, TSO buys (sells)
the power from (to) the market participants according to the difference between
the generation plan/demand and the real power outputs/demand. The payments
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mentioned above are undertaken by all the market participants. In regulating
market, the electricity price is quite different with the day ahead and intraday
market. If the power generation, such as wind power, is more than its generation
plan, the extra part will be sold by TSO with a price much lower than that in the
day ahead and the intraday markets, and the price even could be negative. If the
wind power is less than its generation plan, the extra part will be bought by TSO
whose price is much higher than the day ahead and intraday market.
Code Control Specified Set Points Specified Droop
Settings
Transient
Response
Set
Point
Charges
Denmark Reactive Power Control
Power Factor Control
Voltage Control (>25
MW)
Required 10s
Germany Reactive Power Control
Power Factor Control
Voltage Control
Immediate 1 min
UK 95%-105% 2%-7% 90%
within 1s
Ireland Voltage regulation
similar to AVR
HV side of grid transformer 1%-10% 90%
within 1s
20s
Spain AVR Voltage, Reactive or Power
Factor set points
0-25
(Mvar
pu/
Voltage
dev pu)
Full
response
in 1min
Table: Voltage Control Requiements
Ancillary services
Ancillary services are services that ensure reliability and support the
transmission of electricity from generation sites to customer loads. Energinet.dk
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applies ancillary services to avoid fluctuations in the frequency and
interruptions of supply. Energinet.dk buys 3 different types of reserves, and uses
each type of reserve to balance the power system, depending on the reaction
time. Within 15 minutes of the reaction time the primary reserves will be used.
Within one hour the secondary reserves will be used. If the reaction time needed
is longer than one hour, the manual reserves will be used.
Fig. The functions of different reserves
The need for ancillary services is dynamic throughout the year in terms of
volume and the nature of the ancillary services. There are also regional
differences between Eastern and Western Denmark. Consequently, the volumes
and services on offer are adapted to requirements for specific periods of the year
in Eastern and Western Denmark. The needed ancillary services in November
2011 are described below:
Primary reserves:
The primary reserves are used to adjust the frequency in the respective
synchronous areas. There are two different setups in Western Denmark and
Eastern Denmark. Primary reserves are shared reserves with Continental Europe
(3000 MW) for Western Denmark (± 25 MW) and with the Nordic Region
(1200 MW) for Eastern Denmark (± 22 MW). Western Denmark shares the
3000 MW with the whole Continental Europe area. The 3000 MW has been
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selected to withstand a 10-year extreme event. The Nordic primary reserves of
1200 MW correspond to the largest production unit in the Nordic Region.
Secondary automatic reserves:
The secondary automatic reserves are used to balance a subsystem, i.e. Western
Denmark. There are differences between the setups in Western Denmark and
Eastern Denmark. When the secondary reserves are activated, they replace the
primary reserves so the primary reserves are available again. The secondary
reserves are cheaper in operation than the primary reserves, because the
secondary reserves do not have to react as quickly as primary ones.
Western Denmark (± 90 MW):
- Energinet.dk pays a monthly capacity price for the reserves
- The secondary reserves are mainly provided by conventional power stations
- The reserves are calculated on the basis of the yearly max load
Eastern Denmark (± 160 MW):
- Energinet.dk purchases secondary reserves in blocks of 4 hours
-The secondary reserves are only provided by conventional power stations
- The reserves are calculated on the basis of the largest unit in each Nordic
country.
Manually activated reserves:
Manual reserves are used if the reaction time needed is longer than one hour.
The manual reserves are selected to cover the largest production unit in Western
Denmark and Eastern Denmark respectively. Manual reserves are a part of the
merit order list of the regulating market. When producers sell manual reserves,
producers commit to place a bid in the regulating market.
The costs of ancillary services are correlated with the day-ahead prices. The
day-ahead prices depend, among other variables, on the reservoir levels in the
Nordic Region. Energinet.dk aims to reduce the costs of ancillary services, but
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it does not control the day-ahead prices, which partly determine the costs of
ancillary services. The market controls the day-ahead prices.
Fig. The costs of the ancillary services in the Danish power system
Type of reserve Effect of wind power on the reserve requirement Factors affecting
the additional cost
Primary reserve
(minute to minute
or less)
Nil Geographical
dispersion
Secondary/Tertiary
reserve
(15 minutes, hour to
hour)
Regulating capacity
2% of wind rated capacity at low penetrations and 4% at higher
penetration levels
Costs : €1-3/MWh wind at penetrations up to 10%, at higher
penetrations : €3-4/MWh wind
Geographical
dispersion,
Forecasting
Load following
(4-12 hours)
Efficiency loss due to wind power variations and prediction errors
Reduced fuel use and reduced emissions. Wind is replacing the
most costly power units, operating at the margin, by the forecasted
amount of wind power production. The forecast errors will either
come to the regulating/balancing power market, or be settled by
producers when more accurate closer to delivery time forecasts
appear
Prediction errors
Correlation of
wind power and
load
Production mix
Table: Balancing Requirements and costs
SPANISH ELECTRICITY MARKET
Law and Regularity
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Spanish Royal Decree 436/2004 issued in 2004 clearly formulated the pricing
system and accessory service for wind power. It ruled that a double-track
pricing system is applied for wind power, i.e. a system combined with fixed
price and premium mechanism; meanwhile the Act also presents clear liability
requirement for wind farms, i.e. the wind farms with 10MW capacity and above
must report their WPF results to grids and accept examination from grids. To
guarantee the safe and stable operation of the electric systems and insure the
benefit of the wind plants, Spanish Royal Decree 661/2007 issued in 2007
contains the legal and economic framework for Special Regime production
which including the obligations that the renewable energy plants must fulfill in
order to allow a favourable integration in the electrical system. It includes the
following aspects:
(1) Real time telemetry each 12 seconds to the TSO for all wind power plants with
an installed capacity greater than 10 MW and association into generation
control centers. The items include active power, reactive power, wind speed,
direction, temperature, and pressure etc.
(2) Power factor control with the possibility for the TSO to modify the ranges in
real-time for plants larger than 10 MW.
Spanish Royal Decree 436/2004 issued in 2004 modified the RD 661/2007 to
include the requirement of real-time telemetry every 12 seconds for plants or
clusters of plants larger than 1 MW. It also includes the need for association
into control centers for clusters of plants of the same technology larger than 10
MW. It modifies slightly the power factor ranges for RES and introduces the
possibility to develop voltage control with these types of plants.
ELECTRICITY MARKET
The electricity market is composed by Spain and Portugal. The
market’sclassification and bidding system are similar with the Nordic electricity
market.
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Fig. Framework of the Spanish Electricity market
Until now, the installed capacity of the renewable energies is 20,000 MW in
Spain. In order to accept more wind power, Spain’s grid company issued lots of
administrative regulations and presents clear requirement for wind farms, i. e.
the wind farms should possess the active and reactive power control capability
and the low voltage ride-through (LVRT) capability. To keep the balance of the
power, the grid company provides the control target every 15 minutes to ensure
the priority of the wind power. This control target is usually the installed
capacity of the wind farm. In case of emergency, the grid company balances the
outputs of the wind power by controlling the cycle gas units. The loss is paid by
the final consumers. So there are few restrictions for the wind power. Only
0.2% percentage of the wind power is limited in 2010.
WIND POWER FORECASTING
Wind power forecasting in TSO
Wind power forecasting (WPF) technology is one of the effective measures to
mitigate peak-load regulation pressure, reduce reserve capacity, guarantee safe
and stable operation of the systems, and ensure the participants’ financial
benefit. For TSO, the function of WPF is as follows:
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(1) Determine the reserved capacity in reserve market according to the forecasting
results. The assessment of the requirement and the bidding are influenced by the
forecasting accuracy;
(2) In regulating market (real time market), the buying (selling) of the extra wind
power based on the updating forecasting results every 5 minutes. It is very
important for TSO to keep the stable of the power system. The forecasting
results influence the financial benefits of the participants due to the payment of
the electricity buying (selling) afforded by the power plants.
The related work and responsibility of the Danish TSO and the Spain TSO are
listed below:
a. Danish TSO
Energinet.dk is the TSO of Denmark whose main task is to guarantee safe and
stable operation of the electric systems. Its responsibility is electric storage and
transmission.
Energinet.dk mainly uses two predictions tools: one external and one internal.
The external forecasting method includes 0-12 hours prediction every 5 minutes
and 0-48 hours prediction every hour. The forecasting results take four different
numerical weather predictions into consideration. The internal forecasting
method includes 0-6 hours short term forecast and 12-36 hours day ahead
prediction. The combined forecasting result is based on three meteorological
prognoses.
b. Spanish TSO
Red Eléctrica de España (REE) is the TSO of Spain whose grids connect with
France, Portugal and Morocco. REE was the first company in the world
dedicated exclusively to power transmission and operation of electrical systems.
Its installed capacity of wind power is about 21.3% of the total installed
capacity. Beside study of the forecasting method by itself, REE buys three wind
power forecasting system. The combined forecasting result is based on three
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meteorological prognoses. The precise forecast can be obtained through the
weighted results based on four forecasting tools to guarantee the stable
operation of the electricity system.
Wind power forecasting in wind farms
For wind farms participation, wind power forecasting is the base in the
electricity market. The short term forecast and ultra-short term rolling forecast
are the most important items for generation schedule, bidding in market, the
payment of the extra power and so on. Its main functions are as follows:
(1) In day ahead market, the wind farms join the market according to the short term
forecast. The forecasting result influences the 24 hour’s electric quantity and
bidding price of the next day directly. If the forecasting result is so bad, the
wind plants will pay the expensive compensation for their mistakes in intraday
market.
(2) In the intraday market, the wind farms adjust the hour’s generation plan based
on the updated ultra-short term forecasting result in real time to correct the short
term forecast. The higher the forecast accuracy is, the less the payment of the
extra power will be. The narrower the gap between the generation plan and the
real output is, the less is the TSO’s adjustment required in regulating market. As
a result, the wind farms’ payments for that are reduced.
In general, the accuracy of WPF determines the economic benefit of the wind
farms. It is the most important technique tool for the wind plants to participate
the market.
DONG Energy bids in electricity market and determines the ratio of the wind
power and other generations (such as biomass, coal, oil, gas). They develop the
generation plan according to the market and send it to Energinet.dk. The real
outputs of the power should be consistent with the generation plan, or they need
to pay the loss of the difference between the real and the plan.
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In reserve market, the electric quantity and the electricity price are traded. To
get better wind prognosis for next year, the forecast of DONG Energy includes
monthly forecast and yearly forecast which are served as the reference of
trading in the medium and long term market.
In day ahead market, DONG Energy forecast the wind power of next 24 hours.
The result is served as the reference of the trade of the day ahead market. In
intraday market, ultra-short term forecasting is used to adjust the generation
plan for dealing with the emergence, such as the wind storm, the sudden power
break, and the icing of wind turbines-hub caused by frost and fog. DONG
Energy reduces the economic loss by consulting with Energinet.dk and adjust
the generation plan in time.
Discussion of the wind power forecasting technology
National Laboratory for Sustainable Energy (Risø) in Denmark is leading the
way in wind power forecasting technology research. Its Prediktor system based
on the NWP+WAsP+Power Curves is used in east of the Denmark from 1993.
In 1994, the Zephyr system was developed by Risø and Technical University of
Denmark (DTU). Since its setting-up, Zephyr have been applied in Denmark
and expanded to Spain, Ireland, America, Japan and so on. The valuable
experiences with the system include:
(1) The combination of the numerical weather predictions and statistical forecasts;
(2) Using the numerical weather prediction data which is close to the hub height of
the wind turbines;
(3) Establishing the power curves based on the wind direction & speed of the
numerical weather predictions and the real output of the wind power;
(4) Considering the uncertainty and probability of the forecast;
(5) Obtaining the ensemble prediction result by combining the several numerical
weather predictions;
(6) Measuring the errors of each variable;
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(7) Reducing the forecasting errors by extending the forecasting region;
(8) Training the meteorological knowledge for the technical staff of the electricity
transmission enterprises;
(9) Providing the consulting services under the special situation.
7.2 UNITED STATES OF AMERICA
Different works have shown that the largest share in wind power forecasting
errors comes from the input meteorological forecasts. If for instance a timing
error is present in the meteorological forecasts, it will be directly passed on to
the related wind power forecasts. It should then be envisaged to use several
meteorological forecasts as input, with appropriate combination methods
allowing getting the best out of those inputs. Fortunately, more data, joint
research efforts, and rising commercial interests, will certainly help further
acceleration in the improvement of forecast accuracy. In parallel, the case of
extreme prediction errors, which are the most costly whoever the end-user is,
will necessitate particular attention. If more and more wind power is to be
integrated into the grid, our whole approach to management has to turn towards
probabilistic approaches, permitting to account for these uncertainty aspects, for
the non-symmetric nature of regulation costs, as well as to control the risk of
unbearable costs coming from unforeseen events. This then also means that
easing integration of wind generation via the use of forecasts is not only a
technical problem: all actors concerned should be aware of probabilistic
methods and more sensitive to the concept of risk management.
The Final Rule for “Inter-Connection for Wind Energy” was issued by the
Federal Energy Regulatory Commission on 2nd
June 2005. These regulations are
applicable to plants having more than 20 MW capacity.
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INTERCONNECTION REQUIREMENTS FOR A WIND
GENERATING PLANT
1. Low Voltage Ride Through
A wind generating plant shall be able to remain online during voltage
disturbances up to the time periods and associated voltage levels set forth in the
transition period standard and a post-transition period standard.
Transition Period LVRT Standard
The transition period standard applies to wind generating plants that have either:
(i) interconnection agreements signed and filed with the Commission, filed with
the Commission in unexecuted form, or filed with the Commission as non-
conforming agreements between January 1, 2006 and December 31, 2006, with
a scheduled in-service date no later than December 31, 2007, or (ii) wind
generating turbines subject to a wind turbine procurement contract executed
prior to December 31, 2005, for delivery through 2007.
The maximum clearing time the wind generating plant shall be required to
withstand for a three-phase fault shall be 9 cycles at a voltage as low as 0.15
p.u., as measured at the high side of the wind generating plant step-up
transformer
i. Post-transition Period LVRT Standard
The maximum clearing time the wind generating plant shall be required to
withstand for a three-phase fault shall be 9 cycles after which, if the fault
remains following the location-specific normal clearing time for three-phase
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faults, the wind generating plant may disconnect from the transmission system.
A wind generating plant shall remain interconnected during such a fault on the
transmission system for a voltage level as low as zero volts
ii. Power Factor Design Criteria (Reactive Power)
A wind generating plant shall maintain a power factor within the range of 0.95
leading to 0.95 lagging, measured at the Point of Interconnection, which is the
appropriate measurement point for the power factor standard
iii. Supervisory Control and Data Acquisition (SCADA) Capability
The wind plant shall provide SCADA capability to transmit data and receive
instructions from the Transmission Provider to protect system reliability. The
Transmission Provider and the wind plant Interconnection Customer shall
determine what SCADA information is essential for the proposed wind plant,
taking into account the size of the plant and its characteristics, location, and
importance in maintaining generation resource adequacy and transmission
system reliability in its area.
Code Control Specified Set Points Specified Droop
Settings
Transient
Response
Texas Must be capable of producing a defined
quantity of Reactive Power to maintain
a Voltage Profile established by
ERCOT
Alberta Continuously-variable, continuously
acting, closed loop control voltage
regulation system
95%-105%
Reactive current
compensation
0-10% 95% in 0.1s
to 1s
Quebec AVR system comparable with
synchronous generator
0-10%
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Ontario AVR 95%-105% of rated
voltage
Not more than 13%
impedance from HV
terminal
50ms for 5%
step
ENTSO-E Reactive Power Control
Power Factor Control
95%-105% 2%-7% 90% within
1s
Australia
(Automatic)
95%-105% of normal
voltage
Reactive current
compensation
<2s for 5%
step
Table: Voltage Control Requirements in U.S.A.
A wind plant is required to satisfy the low voltage ride-through standard if the
Transmission Provider shows, through the System Impact Study, that such
capability is required to ensure safety or reliability. The Final Rule adopts the
Point of Interconnection as the point of measurement for the low voltage ride-
through standard .It helps to provide a secure and reliable power supply, and
will facilitate increased use of wind as a generation resource while ensuring that
reliability is protected.
The System Impact Study determines if there is a need for a wind plant to
remain on-line during low voltage events to ensure the safety or reliability of
the system. Requiring low voltage ride-through capability only if the System
Impact Study shows it to be necessary ensures that the increased reliance on
wind plants does not degrade system safety or reliability. It also ensures that the
Transmission Provider does not require a wind plant to install costly equipment
that is not needed for grid safety or reliability. This limits the opportunities for
undue discrimination; a wind plant Interconnection Customer will not have its
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interconnection frustrated by unnecessary requirements to install costly
equipment that is not needed for safety or reliability.
PJM NYISO ISO-NE Ontario IMO
Scheduling in
Energy markets
Day-ahead scheduling;
wind usually submits
zero.
Takes real-time LMP
for energy provided.
Day-ahead scheduling
available but not required.
Up to 500 MW: takes real
time price for all energy
produced beyond day
ahead amounts.
Approach may be revised.
Day-ahead bid option;
or self schedule day
before.
Settle at real-time
nodal price.
Energy from
renewable
intermittent
generation accepted
as generated.
Day ahead market
under development.
Imbalance
settlement
Operating reserves
deviations charges
apply on differential
between day-ahead and
RT levels; (5 MW
dead band; differentials
less than this incur no
deviation charges).
Up to 500 MW, no
penalties. Buy out
shortfalls at real-time
LBMPs. Approach may
be revised.
If deviations, notify
ISO.
No imbalance charges
No penalties;
payments settled at
the hourly spot
market price.
Ancillary
Services
No penalties; payments
settled at the hourly
spot market price.
Wind doesn’t participate
in A/S markets, but is not
precluded from doing so.
Currently no ancillary
services markets. May
have by late 2005.
Considering products
to mitigate variability.
No significant
impacts expected,
but will evaluate
experience.
System has some
tolerance for wind
variability (first 300
MW or so).
Wind Forecasting In operation since
2009:
• DA transmission
security and reserve
adequacy assessments
In operation since 2008:
• Reliability assessment
commitment at DA stage
• RT commitment and
No role so far. Likely
to change with higher
penetrations
No role so far.
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• Developing
automated procedures
• Specific ramp
Forecast
dispatch
• Ramping alert system
under Consideration
Capacity
Calculation
3-yr rolling average, 3-
to-7 pm output, 6/1
through 8/31; default
value: 20% of net plant
rating until actual
operating data become
available. Wind must
bid into day-ahead
market to be a capacity
resource and receive
capacity market
Historic capacity factor,
adjusted for maintenance.
May be adjusted to reflect
correlation with system
peak hours.
Intermittent resources not
required to participate in
day-ahead market to
receive capacity revenues.
Historic capacity
factor, adjusted for
maintenance.
May change to
performance during
the top 100 “critical
hours.”
Yet to be developed.
Probably based on
assumptions at first,
then on experience
as it develops.
Capacity
Recognition
LSEs may procure
capacity bilaterally,
self supply, or
purchase capacity
credits from PJM
capacity auctions. PJM
proposing significant
changes to capacity
requirements to better
incorporate locational
values and demand
response.
LSEs may self supply,
purchase bilaterally, or
purchase capacity in
monthly auctions or
biennial six-month
capacity auctions.
LSEs may self supply
or purchase bilaterally
or purchase in
monthly auctions
No capacity markets
in Ontario at this
time.
MISO SPP ERCOT CAISO
Wind
Forecasting
In operation since
2008:
• DA and intra-day
RAC
• Transmission
security and outage
coordination
• Transmission
security and peak load
analysis
• Indication of ramps
No role so far. In operation since
2008:
• 80% exceedance
forecast used for
DA planning
• To be fully
integrated in new
nodal design, to be
introduced end of
2010
•Developing ramp
Forecast
In operation since 2004:
• Used to calculate
energy schedule in RT
market
• Advisory role in DA
market
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Capacity
Calculation
Regional reliability
organization (MAPP,
MAIN, ECAR)
determines criteria.
Output level that
wind plant equals
or exceeds during
85% of period
defined by top 10%
of load hours.
10% of installed
wind-plant rating
assumed when
assessing regional
capacity sufficiency
Working group
currently studying the
capacity value of wind
generation and
developing improved
models for calculating
the capacity value
Capacity
Recognition
Payments received in
bilateral market for
capacity if designated
as a Network Resource
in MISO meeting
Network Load. As a
designated Network
Resource, must offer
capacity into the Day-
Ahead Market.
No payments
received for
capacity—just
credit toward
overall system
reliability through
reserve margins
Currently no
capacity market.
No payments
received for
capacity—just
credit toward
overall system
reliability through
reserve Margins
No payments received
for capacity—just credit
toward overall system
reliability through
reserve margins.
Resource-adequacy
procurement program
under development by
CPUC,with
implementation by
2006.
MISO NYISO PJM ERCOT
Market timeline DA bids due: 11 a.m.
DA results: 4 p.m.
Re-bidding due: 5pm
RT bids due:
OH -30 min
DA bids due:5 am
DA results:11 am
RT bids due: OH -
75 Min
DA bids due: noon
DA results: 4 p.m.
RT bids due: 6pm
(DA)
DA bids due
(reserves only):
1p.m/4 p.m.
DA results: 1:30p.m/6
p.m.
RT bids due: OH - 60
min
Wind power
bidding,
dispatch,
imbalance
settlements,
deviation
penalties
If wind is a capacity
resource it must bid in
DA market and RAC
•No deviation
penalties
• No wind dispatch,
but this is being
considered
Wind required to
bid in RT market.
DA bidding
optional
• Dispatch signals
provided from
SCED
•Penalty for over
generation in
constrained
situations
• No penalties for
under-generation
If wind is a capacity
resource it must bid
in DA market
•Deviation charges
apply
• Wind dispatch
signals provided in
constrained
situations
• Bilateral market
• Imbalances settled at
RT zonal energy price
•Penalty exemption for
+/- 50% of scheduled
generation
• Ramping limits
Table: Provisions and market schedule of electricity market
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Dispatch
adjusted during
day
Balancing
requirements/
provision
adjusted
during day
Flexible use of
individual
conventional
power stations
International
integration of
intraday/
balancing
markets
Integration of
demand side
response
Effective
monitoring of
market power
possible
UK
system
Liquidity in
Bilateral market
low, so utilities
pursue internal
Balancing and
hold excessive
reserves
Difficult to find
matching
partners for
trade
Only within
portfolio of
utility; difficult to
find matching
partner(s) that
buy/provide
energy matching
demand technical
constraints
Difficult due to
separate energy
and
transmission
markets; illiquid
markets for both
products
intraday
No system-
wide
optimisation
Difficult
because prices
bundle energy,
scarcity, and
start-up cost
German
system
To some extent,
as TSO contracts
energy intraday
to match
changing wind
projections
No, volume of
balancing
services
contracted (not
necessarily
used) is
prespecified;
also,
generators
cannot find
matching
partners to
change unit-
commitment
Only within
portfolio of
utility, difficult to
find matching
partner(s) that
buy/provide
energy matching
demand/technical
constraints
No Possible Difficult
because prices
bundle energy
and start-up cost
Nordpool Yes Access to
Hydro Power
Not necessary
because of hydro
flexibility, not
possible because
trade only hour-
byhour
and prespecified
block-bids
Yes Yes, provides
a program to
Integrate
DSM.
Difficult
because prices
bundle energy
and start-up
cost
Spanish
system
Yes, intraday
markets allow
redispatch
There is a day-
ahead
secondary
reserve market
after the
closure of the
day-ahead
market and 6
additional
markets
between the
intraday energy
markets.
Tertiary reserve
is contracted in
a continuous
market.
Yes No Possible Difficult
because prices
bundle energy
and start-up
cost
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PJM type
system
Yes, ISO can
centrally
coordinate
Intraday
adjustments
Yes, All
markets are
centrally
coordinated.
The ISO can
decide if
resources bid
into the market
are used to
adapt to
intraday
changes or are
used close to
real-time
Yes, Complex
bids and a central
optimization
allow for inter
temporal
optimization of
each power plant
Yes Yes, PJM
implements
several DSM
programmes
to access
potential on
the demand
side.
Yes, bids
specify variable
cost, start-up
cost and
technical
constraints
Table: Comparison of different Power Markets
Mechanism Market Reform
Energy Only UK Maintained, but less inclined to support higher
prices
ERCOT Maintain and improve price signals by raising
price caps
Capacity Market UK Limited capacity market for reliability purposes
only
ERCOT Possible three year forward market
Feed In Tariffs (FiT),
with Contract for
Differences (CfD)
UK Long term contract for differences to provide
revenue certainty for low carbon generation
investment
ERCOT No such reform is under consideration.
Demand Response
UK Successful energy efficiency programs. Limited
mechanisms to procure and call on Demand
Response for reliability purposes. Desire to
increase DR.
ERCOT Policy reforms are focused on improving the
participation of demand in energy and/or
capacity market
Carbon Price Support
and Emissions
Performance Standard
(EPS)
UK Reinforcement of renewable and carbon
reduction policies
ERCOT No such reform is under consideration
Table: Comparison between UK and ERCOT markets
7.3 INDIA
The overall wind energy based capacity installations on an all India basis have
grown at a CAGR of 26% (from 1908 MW as on March 31, 2003 to 19051 MW
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as on March 31, 2013) over the last ten year period. The share of wind energy
based capacity within the overall installed capacity has increased to about 9% as
on March 31, 2013 from 2% as on March 31, 2003 and accounts for about 68%
of overall renewable energy capacity.
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Strength
•Proven technology for electricity generation
•Growth in manufacturing Sector
•Dedicated MNRE at central Level
•Low gestation period as compared to fossil fuel or hydro power projects
•State nodal agencies at state level
•Financial assistance by IREDA
•Specialized institutions and organisations
•Comprehensive Resource Assessment
•Environment friendly clean technology
•No fuel inputs
•Guaranteed off-take- long term PPA with Discoms
•Competitive manufacturing base
Weakness
• Intermittent source of power supply
•Low capacity utilisation factor
•Higher cost as compared to fossil fuel based power generation
•Small wind farms are not techno-economically viable
•Potential sites are inaccessible
• Inadequate grid infrastructure
•Bird and Bat Mortality
•Noise Pollution
•Considering the risk involved, the financing rates are high
•Absence of Single window Clearance System
Opportunities
•Huge untapped potential
•Continuing electricity demand-supply gap
•Distributed/ decentralized generation
•Escalation in the cost of fossil fuel-based power generation
•Shortage of fossil fuel (especially coal)
•Fiscal incentives and promotional activities by government
• Interest and capital subsidies
•Remunerative Returns on Equity
•REC and RPO
•CDM credits
•Hybrid models
•100% FDI is allowed through automatic route
•Third party sale at mutually agreed tariff
Threats
•Matured Market
•Wind Power subsidies and incentives may be rationalized or pegged down (GBI, AD)
•Land cost may shoot up
•Discounts provided by manufacturers may dry up
•Technological process may be on hold
•Delay in receipt of payments from DISCOMS (considering the current financial conditions of the DISCOMS)
•Shift in focus
Wind Energy Sector
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INDIAN WIND GRID CODE
The draft Indian Wind Grid Code was formulated by the Center for Wind
Energy Technology in 2009. The primary objective of IWGC is to establish the
technical rules which all wind farms must comply within relation to their
planning, connection and operation on the Indian grid. The matter of non-
compliance of IWGC shall be reported to Member Secretary, RPC or the
desgnated agency by any agency/RLDC.
Plannning Code for Transmisssion Systems Evacuating Power
The Planning Code applies to transmission licensees, wind farms, SEBs, CTU/
STU and distribution licensees involved in developing the transmission/
evacuation system for wind power evacuation.
PLANNING CRITERIA
1. Study of transmission system for wind power evacuation
High Wind Generation refers to:
a. 100% capacity factor for wind farms connected below 66kV.
b. Mininmum 90% capacity factor for wind farms connected at 66kV or
110kV or 132 kV.
c. Minimum 80% capacity factor or wind farms connected above 132kV.
i) System Peak Load with High Wind Generation
All generating units in a region during Peak Load conditions will
run at or near its maximum capacity. Power flow will take place at
a higher transmission level and evacuation planning of wind farm
shall not cause any congestion in network during peak load
condition.
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ii) System Light Load with High Wind Generation
All the available wind power should be evacuated under system
light load condition.
iii) Local Light Load with High Wind Generation
All the wind power is evacuated to the system during light load
condition in local areas.
2. Contingency study
N-1 contingency criteria is not applicable in case of wind farms because
their plant load factor is lesser than conventional generators. N-1
contingency criteria is applicable only to wind farms connected at 220kV
and above voltage level.
3. Reactive Power Compensation
Reactive Power injection from wind farms is least expected, so the power
factor range is 0.95 leading to 0.95 lagging unlike conventional
generators which have a power factor range of 0.95 leading to 0.85
lagging. Dynamic VAr compensation is used to prevent the voltage
collapse during high wind generation.
Country India UK Germany Canada
Power Factor
Range
0.95 leading to
0.95 lagging
0.95 leading to
0.95 lagging
0.95 leading to
0.95 lagging
0.95 leading to
0.90 lagging
Connection Code For Wind Farms
It specifies the minimum technical and design criteria which must be satisfied
by any wind farm seeking connection to ISTSs/STSs/STUs.
1. TRANSMISSION SYSTEM VOLTAGE REQUIREMENTS
a. Transmission System Voltage Range
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The wind farm must be able to deliver available or rated power when
the voltage at grid connection point remains in following range:
Nominal % Limit of variation Maximum Minimum
400 +5% to -10% 420 360
220 +11% to -9% 245 200
132 +10% to -9% 145 120
110 +10% to -12.5% 121 96.25
66 +10% to -9% 72.5 60
33 +5% to -10% 34.65 29.7
Table: Voltage withstand limits for wind farms (kV)
b. Voltage Unbalance
It is defined as the deviation between the highest and lowest line
voltage divided by the average line voltage of three phases. The WTG
connection to an unbalanced system will cause negative phase
sequence current to flow in the rotor of the machine. Wind farms must
be able to withstand following voltage unbalance limits:
Voltage Level (kV) Unbalance (%)
400 1.5
220 2
<220 3
Table: Voltage Unbalance Limits
2. Reactive Power Capability of wind farms
Wind farms connected at 66kV and below shall maintain power factor
between 0.95 lagging and 0.95 leading at grid connection point.
3. Frequency Tolerance Range
i) Wind farms must be capable to operate continuously for system
frequency range of 47.5 to 51.5Hz.
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ii) Above 51.5 Hz and below 47.5 Hz allowable frequency tolerance
range of wind farms must remain in accordance with wind turbine
specifications.
iii) Wind turbine must remain grid connected when rate of change of
frequency is within 0.5 Hz/sec.
4. Disconnection of Wind turbine from grid
a. Wind farms must have voltage and frequency relays for disconnection
of wind turbines from grid under abnormal voltage and frequencies.
b. Wind farms connected below 66kV can be disconnected from grid
during system faults and fault ride through capability is not
mandatory.
5. Fault Ride Through Requirements
During Fault Ride Through, the WTGs in the wind farm must have the
capability to meet following requirements:
a) Minimize the reactive power drawl from the grid.
b) The wind turbine generators must provide active power in proportion
to retained grid voltage as soon as fault is cleared.
Nominal System Voltage (kV) Fault Clearing Time,T (ms) Vpf (kV) Vf(kV)
400 100 360 60.0
220 160 200 33.0
132 160 120 19.8
110 160 96.25 16.5
66 300 60 9.9
Table: Fault clearing time for various system nominal voltage levels
where Vf = 15% of Nominal System Voltage
Vpf = Minimum voltages mentioned in IWGC for Reactive
Power Compensation
6. Grid Protection
Limits for release levels and release times of:
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Under frequency
Over frequency
Under voltage (fault ride-through behaviour must be considered)
Over voltage
Operating Code for Wind Farms
It specifies the operating conditions that the wind farms must comply with for
safety and reliable operation of the grid and must be applicable to the wind
farms connected to the grids and the SEBs/STUs/SLDCs/RLDCs/SSLDCs.
The wind farm must operate at the same voltage and frequency conditions as
mandated under connection conditions. The Active power and power factor
must also must remain same as the connection conditions.
1. Reactive Power and Voltage Control
The wind farms must not draw reactive power from the grid. VAr
exchanges with the grid shall be priced as follows:
a. Wind farm owner pays for VAr drawl from grid when voltage at the
grid connection point is below 97%
b. The wind farm owner gets paid for VAr given to the grid when
voltage is below 97%
c. The wind farm owner gets paid for VAr drawl when voltage is above
103%
d. The wind farm owner pays for VAr given to the grid when voltage is
above 103%
The wind farm operator must minimize the VAr drawl from the grid
when the voltage at the grid connection point is below 95% of the rated
voltage ,and must not supply VAr to grid when voltage is above 105%.
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2. Ramp Rate Limits
These are applicable to grid connected wind farms with installed capacity
50 MW and above. The WTGs must have two ramp rates:
a. 10 minute maximum ramp rate
b. 1 minute maximum ramp rate
Wind Farm Installed Capacity
(MW)
10min Maximum Ramp
(MW)
1 min Maximum Ramp
(MW)
50-150 Installed Capacity/1.5 Installed Capacity/5
>150 100 30
Table: Ramp rate limits for wind farms
This is similar to Irish Grid Code where ramp rate averaged over 1minute
should not exceed 3 times the average ramp rate over 10 minutes.
3. Scheduling Process
When wind penetration increases, it would be necessary to carry out wind
energy forecasting to know the predicted wind power in next day on
hourly basis so as to minimize the scheduling errors. The system operator
must aim at utilizing the wind energy fully and the Merit Order dispatch
shall not be allowed for wind farms.
4. Forecasting
Centralized wind forecasting facility must be provided in area with
aggregated capacity of 200MW and above. The centralized wind
forecasting facility must be installed by system operator or wind
developer to forecast the wind flow over a certain geographic area (for a
cluster of wind farms).
The wind energy forecasting system must forecast power based on wind
flow data at the following intervals:
i) Day- ahead forecast:
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Wind power forecast with an interval of one hour for the next
24hours for the aggregate wind farms. It is done to assess the
probable wind energy that can be scheduled for the next day.
ii) Hourly forecast:
Wind Power forecast with a frequency of one hour and interval of
30minutes for the next 3 hours for the aggregate wind farms. It is
necessary to minimize the forecasting error that can occur in the
day ahead forecasting of the wind power.
DATA PROCESSING
Wind farms shall give information about:
Active Power Output
Reactive Power Output
Status
Set point values of grid operator to wind farm:
Reactive power (MVAr or power factor)
Active Power Reduction
Wind farms should behave more like conventional power plants and support the
grid. To set-up a grid connection for wind farms, it must match the standard grid
code.
Complementary Commercial Mechanism as per IEGC
Wind farms =10MW & above connected to 33kV or above should give their :
1. Outage planning
2. Day ahead forecast with an interval of 15 min. (max 8 revisions in 3 hr. time
slot ) with accuracy of 70%
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In case of wind generators ,if :
a. Generation is beyond +/- 30% of the schedule then wind generator will
bear UI charges
b. Generation within +/- 30% of the schedule then host state will bear UI
charges which shall be shared among all the States of the country in the
ratio of their peak demands in the previous month based on the data
published by CEA, in the form of a regulatory charge known as the
Renewable Regulatory Charge operated through the Renewable
Regulatory Fund (RRF), operated through NLDC.
Energy Accounting of Wind Generator
Inter-State
The transactions would be between the wind generator and the purchasing
State at the contracted rate for actual generation upto 150% of the scheduled
generation.
The difference of actual generation from the schedule for the purchasing
State would be settled at the UI rate of the Region of the purchasing state
through the RRF.
The implication due to deviations of actual generation within +/- 30% of the
scheduled generation would be settled with the host State through the RRF.
The deviations outside +/- 30% would be settled directly between the host
State and the Wind Farm.
Intra-State
The transactions would be between the wind generator and the host State at
the contracted rate for actual generation.
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The implication due to deviations of actual generation within +/- 30% of the
scheduled generation would be settled through the RRF.
The implication due to deviations outside +/- 30% would be settled directly
between the host State and the Wind Farm
Scheduling Provisions for Wind Generators as per IEGC
For capacity and voltage level below the levels mentioned in IEGC, as well
as for old wind farms it could be mutually decided between the Wind
Generator and the transmission or distribution utility, as the case may be, if
there is no existing contractual agreement to the contrary.
The schedule by wind power generating stations may be revised by giving
advance notice to SLDC/RLDC, as the case may be. Such revisions by wind
power generating stations shall be effective from 6th
time-block ,the first
being the time –block in which notice was given.
There may be maximum of 8 revisions for each 3 hour time slot starting from
00:00 hours during the day.
Forecasting for Wind Generation
As per Para 3 of Annexure-1 ( Complementary Commercial Mechanism) of IEGC
Wind energy being of variable nature, needs to be predicted with
reasonable accuracy for proper scheduling and dispatching.
Wind generation forecasting can be done on an individual developer basis or
joint basis for an aggregated generation capacity of 10 MW and above
connected at a connection point of 33 kV and above.
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If done jointly, the wind forecasting facility shall be built and operated by
wind developers in the area and sharing of the cost shall be mutually
discussed and agreed.
As per Para 4 of Annexure-1(Complementary Commercial Mechanism),
IEGC
The wind energy forecasting system shall forecast power based on wind
flow data on day ahead basis.
Wind/ power forecast with an interval of 15 minutes for the next 24
hours for the aggregate Generation capacity of 10 MW and above.
Types of Wind Energy Forecast Required based on Time Horizon
Energy Forecast Over day month and year – Cash Flow of Wind Generator
MW Forecast- Day ahead useful for System operation
Ramp Forecast- Hours ahead -to reduce forecast gap
Operational Requirements as per IEGC
As per Regulation 5.2 (u) of IEGC,2010:
System Operator ( SLDC/RLDC) shall make all efforts to evacuate the available
solar and wind power and treat them as a must run station.
However, system operator may instruct the wind or solar generator to back
down on consideration of grid security or safety of equipment or personnel and
the generators shall comply these directions.
For this Data Acquisition system facility shall be provided for transfer of
information to concerned SLDC/RLDC.
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SLDC/RLDC may direct a wind farm to curtail its Var drawal/injection in case
the security of grid or safey of any equipment or personnel is endangered.
During the wind generator start-up, the wind generator shall ensure that the
reactive power draw shall not affect the grid performance.
As per Regulation 5.3 (g) the SLDC shall take into account the wind energy
forecasting to meet the active and reactive power requirements.
SPECIFICATIONS REQUIRED DURING DIFFERENT PHASES OF
WIND FARM
DISCIPLINE/
PROJECT
STATUS
PRE CONSTRUCTION DURING
CONSTRUCTION
DURING OPERATION
MARKET
SPECIFICATIONS Wind assessment review
Building Permit Review
Grid Connection
License/Feed In License
National Specifications-
Remuneration, grid code
etc
Fulfilment of
Building/grid
connection
License
Requirements
Acknowledgement
of OP license
Wind assessment
update
Operation License-
review
Grid Connection/
Feed In License
Review
Grid Code- changes,
requirements,
fulfilment
TECHNICAL
SPECIFICATIONS Review on site Layout
Wind Turbine Technical
Review (track record,
suitability etc.)
Electrical Works Review
(Internal grid, substation,
connection to the grid)
Civil Works Review
(Foundations, Geotech,
Accesses, Crane Pads,
SE building)
Overlapping Issues (eg
Construction Schedule
Review, grid
compliance)
Construction Monitoring
Supervision of
fulfilment of
technical
requirements
Regular
Construction
Reports
Supervision/
review of
Equipment tests
Commissioning of
WTG
Supervision and
Control of Take
Over Procedure
WTG inspection
(end of warranty)
Specific component
inspections
Scada Data analysis
general inspections,
end of warranty
inspections etc
Grid code needs/
changes
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CONTRACTUAL
SPECIFICATIONS TSA, O&M, Warranties
BoP/EPC
Grid Connection
Agreement
PPA / CPA PPA Review
(Changes)
Land Agreements
Overlapping Issues (e.g.
contractual
interaction during construction)
Construction Monitoring
- Fulfilment of Contractual
Obligations
- payment supervision
WT- O&M
Agreement
Management
Agreement
PPA Review
(Changes)
In all contracts:
review in case of
changes
FINANCE
SUPERVISION
Cash Flow review (CAPEX,
revenues,
OPEX, etc.)
Construction Monitoring
- Approval of Draw Downs
and review of
Cash Flow during
Construction Phase
- regular construction
reports
Financial operation
Monitoring
Cash Flow
Assessment
ANCILLARY MARKET
Two main Ancillary Services – one being Reserves and the other Frequency
Keeping, however, there are other ancillary services such as Voltage Support.
A. The Reserve Market
• As part of the System Operator responsibilities, Transpower are required
to keep enough generation in reserve to cover the risk of the largest
generator tripping (stopped generating suddenly) and subsequently are
required to keep frequency at around 50 Hz in both the North and South
islands.
• There are two types of reserve required – Fast Instantaneous Reserve
(FIR) and Slow Instantaneous Reserve (SIR). FIR is required to respond
within 6 seconds of frequency falling and sustain this extra generation for
at least 60 seconds. SIR is required to respond within 60 seconds of a
frequency event and be maintained for up to 15 minutes if required.
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• The energy and reserve markets can affect each other. Eg. When the
market is short of reserve, a generating unit may be backed off to provide
reserve resulting in a higher spot price
B. The Frequency Keeping Market
• It is a separate market from the energy market, here the companies
providing frequency keeping compete by offering a fee for the service for
each half hour trading period. The frequency keeper is required to
maintain frequency within a band of 50.2 Hz to 49.8 Hz.
• Governors on each generator monitor the state of frequency and control
the amount of water or steam flowing through the turbine to adjust the
level of generation to suit the frequency level.
• For example if generation is constant and demand suddenly increases, the
waves above are stretched out and the frequency falls which requires
extra generation to get back to 50 Hz and as a result of this the frequency
keeper increases their generation to stabilize the frequency.
• Drastic drop in Hz is potentially disastrous. One unit tripping can cause
Hz to fall, which leads to another unit tripping
and causes other
generators to trip. This is commonly known as cascade failure and would
lead to a blackout – such as those seen in New York a couple of years
ago.
Automatic demand management in IEGC.
Para 5.4.2.(d) : The SLDC through respective State Electricity
Boards/Distribution Licensees shall also formulate and implement state-
of-the-art demand management schemes for automatic demand
management like rotational load shedding, demand response (which may
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include lower tariff for interruptible loads) etc. before 01.01.2011, to
reduce overdrawlin order to comply para5.4.2 (a) and (b) .
Wide area measurement systems (WAMS)
•Two schemes in the Northern and Western Regions of India.
•The scheme in Northern Region is a pilot scheme for installation of four Phasor
Measurement Units (PMUs) at certain identified locations. Commissioned in the
end of April 2010 and data has been flowing since then to the system operator
of Northern Region.
•The scheme in Western Region is a pilot scheme for installation of 28 PMUs at
various locations in the Western Region. Optimum location through software
program.
State
Wheeling and
transmission
Charges
Banking FiT (INR
per unit)
Cross subsidy
surcharge (CSS) RPO
Karnataka 5% wheeling
charges and losses
12 months, 2%
banking charges 3.70 Nil
7-10% Captive &
Open Access
(OA) -5%
Tamil Nadu
HT/EHT: 5% for
all OA consumers
LT: 7.5% for all
OA consumers
1 year TOD
banking
Charges @ 5% of
energy generated
in billing month
3.51
50% CSS
applicable for
WEGs
9%
Gujarat Normal OA
charges
1 month banking
for captive
consumers
4.61 Nil 7% in FY 13
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Maharashtra Normal OA
charges 12 months
Zone 1: 5.67
Zone 2: 4.93
Zone 3: 4.20
Zone 4: 3.78
25% CSS
2010-11: 6%
2011-12: 7%
2012-13: 8%
2013-16: 9%
Rajasthan
50% of normal
transmission
charges
Banking and
withdrawal on six-
month basis.
Withdrawal not
allowed in Dec,
Jan and Feb
4.46-4.69 Nil
5.1% for wind
with overall
7.1% in FY 13
Andhra
Pradesh
As per rules and
regulations of the
Commission
Allowed 3.50
50% CSS for
generation from
renewable
sources
5%
Table: Various Regulatory Provisions for Wind Sector in India
Nord Pool PJM NEMMCO IEX
Participation Voluntary for day-
head and ,
adjustment market
Compulsory for
day-ahead market
Compulsory for
day-ahead spot
Voluntary
Market Offerings Day-ahead spot,
hour ahead,
Forwards, Futures,
Options
Day-ahead spot,
real-time balancing,
capacity credits
market
Day-ahead spot and
short-term forwards
Day-ahead spot
Bidding type Double-sided Double-sided Double-sided Double-sided
Adjustment
Market
Elbas; intra-day
auction market
Bid-quantity can be
changed till gate
closure
-
Not available
Real time/
Balancing market
Counter trade for
real time, .
Participants are
given MCP
Deviations are
traded in real-time
Through purchase
of Ancillary .
services, reserve
capacity buying
Deviations are
subjected to UI
charges
Pricing rule Zonal pricing Nodal pricing Zonal pricing Zonal pricing
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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Pricing type Ex-ante Ex-post Ex-post Ex-ante
Risk management Forwards, Futures,
Options
FTRs-ARRs,
Bilateral OTC,
Multi-settlement
market, virtual
bidding, Financial
trading@ NYMEX
Bilateral OTC,
Derivatives on
Sydney future
exchange
Bilateral OTC
Congestion
management
Area splitting Security
constrained
economic dispatch
Locational signals
for transmission
tariffs
Area splitting
Transmission
Losses
Included in zonal
price
Included in LMP To be purchased by
generators
To be purchased by
participants
Time blocks Hourly blocks Hourly blocks Half-hourly blocks Hourly blocks
Table: Consolidated overview of Nord Pool, PJM, NEMMCO, IEX
8. SOLUTIONS FOR INDIA –WIND ENERGY
Wind energy generators are mandated to forecast the wind generation,
since wind forecasting software packages are available in the market.
The philosophy of limited applicability of UI charges to Wind generators
is that it is seen that they can forecast generation of wind energy with an
accuracy of at least 70%. Therefore, within the band of +/-30% variation
from the forecast, they should not be subjected to UI charges.
However, for variation more than that, they are liable to be included in
the UI mechanism, beyond this limit.
The UI mechanism is used only in India. It has been introduced in South
Africa only last year. It is suggested that penalty mechanism other than
UI charges must be adopted in India.
The wind power is forecasted in 15minute time block (96 time blocks in a
day) in India. Internationally, the wind power is forecasted on an hourly
basis. An hourly forecast system must be used in India.
Analysis of Forecasting and Scheduling of Wind Power for Grid Integration in
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Internationally, an accuracy of 90% is achieved on the basis of
calculation of absolute mean error. But in India, absolute error is
computed, which provides accuracy of 70%.
India must develop technologies like radar for forecasting local wind.
India presently has two satellites-INSAT 3A and Kalpana 2 for
forecasting of global winds.
In order to prevent gaming by the wind generator by always playing safe
and declaring on the lower side during times of low frequency, a cap of
+50% has been put.
This provision is being mandated for wind generators with an aggregate
capacity of 10 MW or more and for solar generators with an aggregate capacity
of 5 MW or more, connected at a connection point of voltage level of 33 kV and
above, whose Power Purchase Agreements have not been signed as on 3.5.2010,
the date of coming into effect of the new IEGC.
9. CONCLUSION
If hourly wind forecasting replaces the 15 minute time block wind forecasting in
India and absolute mean error is used to compute accuracy, then India will be
able to achieve 90% wind forecasting accuracy like U.S.A. and Europe.
10. REFERENCES
Ackermann, Thomas (Editor). Wind Power in Power systems. Wiley and Sons,
2005.
http://www.windpowerinpowersystems.info/
Holttinen, H. The impact of large scale wind power on the Nordic electricity
system. VTT
Publications 554, 2004 (PhD Thesis)
http://www.vtt.fi/inf/pdf/publications/2004/p554.pdf
EWEA. Wind Energy. The Facts. 2004; www.ewea.org
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73 National Power Training Institute (NPTI) | ICRA Management Consulting Services Ltd (IMaCS)
Proceedings of Fourth International Workshop on Large-Scale Integration of
Wind Power and Transmission Networks for Offshore Wind Farms, held in
Billund, Denmark, Editors:
Matevosyan, J. and Ackermann, T., published by the Royal Institute of
Technology, Stockholm, Sweden, 2003.
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Glasgow, Scotland, Editors:
Matevosyan, J. and Ackermann, T., published by the Royal Institute of
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in EU electricity systems. Economic and technical issues. ECN-C--05-019
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to Implement the Campaign for Take Off – Business Plan, February 2000.
Acker, T. 2007. Arizona Public Service Wind Integration Cost Impact Study.
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Almon, B. 2011. Personal communication with Brian Almon, Public Utility
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American Wind Energy Association (AWEA). 2011a. U.S. Wind Industry
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American Wind Energy Association (AWEA). 2010. AWEA Small Wind
Turbine Global Market Survey, Year Ending 2009. Washington, D.C.:
American Wind Energy Association.
AWS Truepower. 2011. windTrends Bulletin: 2010 Q4. Released March 1,
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Bloomberg New Energy Finance (Bloomberg NEF). 2011. North America
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Bloomberg New Energy Finance (Bloomberg NEF). 2010. Q3 2010 Earnings
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Bonneville Power Administration (BPA).
2011 a. McNary-John Day 500-kilovolt Transmission Line.
http://www.bpa.gov/corporate/RecoveryAct/mcnary-johnday.cfm.
1. Bonneville Power Administration (BPA). 2011b. BPA Announces
Decision to Build Central Ferry-Lower Monumental Line. March 24,
2011.
http://www.bpa.gov/corporate/BPANews/ArticleTemplate.cfm?ArticleId=articl
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Brooks, D., E. Lo, R. Zavadil, S. Santoso and J. Smith. 2003. Characterizing the
Impact of Significant Wind Generation Facilities on Bulk Power System
Operations Planning: Xcel Energy – North Case Study. Prepared for the Utility
Wind Integration Group. Arlington, Virginia: Electrotek Concepts.
Recommended