Bear Creek System Impact Study

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Bear Creek Hydro IPP Interconnection System Impact Study August 2005

XXXX

Bear Creek Hydro Generation Project

System Impact Study

Report No.SPA 2005-27

August, 2005

System Planning (Lower Mainland & Vancouver Island)

British Columbia Transmission Corporation

British Columbia Transmission Corporation, 2005. All rights reserved.

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DISCLAIMER OF WARRANTY, LIMITATION OF LIABILITY

This report was prepared by BCTC solely for use by XXXX for the purposes ofconnecting Bear Creek Hydro IPP into the Transmission System. This report is based on

information provided to BCTC as of the date of this report. Accordingly, this report issuitable only for such purposes, and is subject to any changes arising after the date of this

report.

Unless otherwise expressly agreed by BCTC, BCTC does not represent or warrant theaccuracy, completeness or usefulness of this report, or any information contained in this

report, for use or consideration by any third party, nor does BCTC accept any liability out

of reliance by a third party on this report, or any information contained in this report, orfor any errors or omissions in this report. Any use or reliance by third parties is at their

own risk.

________________________________________________________________________________________________________________________________________________ This document contains proprietary information and shall not be reproduced in whole or in part without the prior written consent of BCTC

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Executive Summary

This report indicates the interconnection cost estimates associated with the

interconnection of the proposed 19.3 MW of generation at XXXXs Upper Bear Creek

and Lower Bear Creek hydro electric generating facilities. The report also provides atechnical review and identifies major requirements to connect the proposed generation to

the Transmission System.

In order to connect the proposed 19.3 MW of generation at Upper and Lower Bear Creek

to the Transmission System, the following requirements are identified:

IPP to build a new 138 kV transmission circuit from its generating facilities to anew 138 kV substation next to the Clowhom substation. This new Bear Creek IPP

station will share the same ground grid with Clowhom. An overhead tie of no

more than 200 meters will tie this new station to Clowhom and power will go into

the Transmission System at Clowhoms existing 1L44 connection.

Sections of transmission circuit 1L44 must be upgraded to a higher summerthermal rating. Clowhom to Sechelt Creek Tap section must be upgraded to a

summer rating of not less than 240 amperes and Sechelt Creek Tap to Sechelt

section to a summer rating of not less than 300 amperes.

Line protection of 1L44 must be modified to including tripping of the circuitbreaker at the entrance to the new Bear Creek IPP station.

Bear Creek IPP transformers must have grounded wye HV and delta LVconfiguration.

Communication facilities will be required to enable communication with controlcentres.

In connection with the above, the subsequent Interconnection Facilities Study report and

PIR will discuss additional requirements.


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Table of Content

Executive Summary

1.0 Introduction 2

2.0 Purpose of Study 3

2.1 Terms of Reference 3

3.0 Data and Modeling 4

4.0 System Studies 4

4.1 Steady State Power Flow study 54.2 Short Circuit study 5

4.3 Transient Stability study 6

4.4 Protection study 74.5 Remedial Action Schemes 7

4.6 Black Start Capability 7

5.0 Reinforcement and Upgrades 8

6.0 Conclusion 8

AppendixOne-line Diagram: Normal System before Bear IPP 9

One-line Diagram: Normal System after Bear IPP 10

One-line Diagram: System with Bear IPP, 1L35 out of service 11One-line Diagram: System with Bear IPP, 1L32 out of service 12

Machine Data; Salient Pole Generator GENSAL 13Machine Data: Simplified Excitation System SEXS 14

Machine Data: Hydro Turbine-Governor HYGOV 15

Stability Plot 1: 10 cycle fault on Bears 138 kV line betweenUpper and Lower Bear near Lower Bear 16

Stability Plot 2: 9 cycle fault on Bears 138 kV line between

Lower Bear and Bear Station near Bear station 17Stability Plot 3: 9 cycle fault on 1L32 between SEC and

Gibsons (GIB) near SEC 18

Stability Plot 4: 8 cycle fault on 1L35 between SEC and

Malaspina (MSA) near SEC 19

Stability Plot 5: 9 cycle bus fault at SEC 20One-line Diagram: Clowhom AC Conceptual Protection 21

Control Diagram: Clowhom Generating Station 22Control Diagram: Bear Station BRK 23


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1.0 Introduction

XXXX (the IPP) is proposing to develop two hydro electric generating facilities at

Upper Bear Creek and Lower Bear Creek in the Clowhom Peninsula region of the

Sunshine Coast. These two hydro electric generating facilities are collectively referred toas the Bear Creek Hydro IPP in this report.

Upper Bear has a single 13.8 kV 13 MVA hydro generating unit running at 0.9 powerfactor. The maximum output from this unit is 11.7 MW. Lower Bear has a similar unit

rated at 8.5 MVA, with a maximum output of 7.65 MW. The distance between Upper

and Lower Bear is 7.5 km. XXXX proposes to build a 138 kV overhead transmission line

from Upper Bear to Lower Bear, and extend this line by a further 6.2 km to connect to theTransmission System near the Clowhom substation.

The Point of Interconnection is near the Clowhom Generating Station (COM). XXXXwill construct a 138 kV Bear Creek (BRK) substation near COM. The tie between COM

and BRK substation will not be more than 200 meters. Power generated by Bear CreekHydro IPP will enter the transmission system by way of the existing COM tie to

transmission line 1L44 which runs between COM and Sechelt (SEC).

The proposed in service date is September 2006.

The following diagram shows the IPP with its proposed generators, new 138 kVtransmission circuit, new BRK substation, transmission circuit 1L44, and nearby BCTC

substations (COM, SEC and Sechelt Creek IPP (SCG)).

SEC 138 COM 138

1L44

Bear Station

SCG T2

G2

Lower Bear

7.65 MW

Sechelt

Creek IPP

(138 kV)

T1

G1

Upper Bear

11.7 MW

Transmission

System


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2.0 Purpose of Study

To ensure safe and reliable operation of the Transmission System with Bear Creek HydroIPP added to the system, the purpose of this study is to assess the impact on the

Transmission System arising from the integration of the IPP. The study identifies

Transmission System constraints and proposes required upgrades and reinforcements forthe network. The study also identifies the IPP requirements in order to connect to the

Transmission System.

2.1 Terms of Reference

This Interconnection Impact Study (IIS) was conducted under the following Terms of

Reference:

WECC reliability Criteria

Existing planning and operating criteria, standards and procedures that conform toWECC Reliability Criteria, to determine necessary transmission system

reinforcements have been followed.

Technical Studies

The following studies have been performed:

- Power flow analysis to assess the impacts on transmission network and operatingvoltage profiles.

- Transient stability analysis to assess system dynamics performance.- Protection study to assess protection requirements for the Transmission System.

Designations

The following are BCTC operating designations used throughout this report.

Item Operating Designation

BC Hydro BCH

BC Transmission Corporation BCTC

XXXX Break Creek Hydro generatingstation

IPP

Bear Creek IPP substation next to COM BRK

System Control Centre SCC

Northern Control Centre NCC

South Interior Control Centre SIC


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Clowhom Generating Station COM

Sechelt Creek IPP Tap SCG

Sechelt substation SEC

Gibsons 138 kV substation GIB

Pender Harbor 138 kV substation PHR

Malaspina 138 kV substation MSA

138 kV transmission circuit connectingCOM, SCG and SEC

1L44

138 kV transmission circuit connecting

SEC and GIB

1L32

138 kV transmission circuit connecting

SEC, PHR and MSA

1L35

Interconnection Impact Study IIS

3.0 Data and Modeling

The study was carried out based on the data and information provided in the IPPs

Generation Interconnection Application dated March 1, 2005. The data provided in the

Application was used in the analysis and the results of the study are dependent on theiraccuracy. Whenever there was missing data required for the study, typical data for similar

equipment was used. Bear Creek Hydro IPP generating equipment with their respective

PSS/E models GENSAL, SEXS and HYGOV, are shown in the appendix.

A 2006/07 Heavy Winter load flow base case was used as the basis for the study. For the

Clowhom Peninsula where Bear Creek Hydro IPP will be connected, the following

assumptions were used:

COM generation 33 MW

SCG generation 16 MW

Upper Bear generation 11.7 MW

Lower Bear generation 7.65 MW

1L44 summer rating (COM to SCG) 170 amps

1L44 summer rating (SCG to SEC) 260 amps

1L44 circuit length 37.3 km

4.0 System Studies

Load flow, short circuit and transient stability studies were carried out to evaluate theimpact of the IPP on the Transmission System, and to identify the requirements in order

to connect the Bear Creek Hydro IPP into the Transmission System.


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4.1 Steady State Power Flow Study

The IPP connects to the Transmission System via COM. All its generation,

together with those from COM and SCG, are evacuated to the main grid viatransmission line 1L44. 1L44 runs from COM to SEC, and collects generation

from COM and Bear Creek Hydro IPP at COM, and generation for SCG at some

point 6 km from COM. There is no customer load on 1L44 between COM andSEC. Loading on the transmission line depends entirely on the output from the

generators at COM, SCG and Bear Creek Hydro IPP. The present role of 1L44 isto transfer all the power from the generators connected to this line to the main

grid at SEC. The following table shows the existing thermal rating of 1L44, and

the flow on 1L44 before and after the integration of Bear Creek Hydro IPP.

1L44 Rating and Flows in Amperes

COM-SCG SCG-SEC

Rating No IPP With IPP Rating No IPP With IPP

Summer 170 137 220 260 205 288

Winter 280 137 220 440 205 288

It can be concluded from the above table that the summer thermal rating for the

entire length of 1L44 will be exceeded when Bear Creek Hydro IPP is added and

when all Bear Creek Hydro IPP, COM and SCG generators are generating at theirmaximum capacity.

There is no overloading on 1L44 during the winter for the above scenario.

In the event that 1L35 between SEC and MSA or 1L32 between SEC and GIB isout of service, all generation from the Clowhom Peninsula will flow into the grid

on the remaining circuit. There is sufficient capacity in the circuit and no overload

will occur. No abnormal voltages have been observed.

4.2 Short Circuit Study

Three Phase Short Circuit in MVA at the SEC and COM station buses are

affected by generation addition. The calculated fault levels are based on existing

system with no generation addition and with the proposed generation addition.

The calculated fault levels are derived from the Protection Planning ASPEN One

Liner Fault Study Case BRK2005_asp2004r2.olr. The power system is modeled

with 1.0 pu pre fault voltage, no shunts, and in the subtransient time frame. Thegeneration addition is modeled based on data provided by the customer.

IPP generation at Bear Creek Hydro IPP consists of Upper Bear and Lower Beargenerators. Upper Bear will have one 13 MVA generator @ 13.8 kV with


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subtransient reactance of 1.99% and Lower Bear will have one 8.5 MVAgenerator @13.8 kV with subtransient reactance of 2%. The IPP transformers are

grounded wye on the 138 kV and delta on the 13.8 kV side.

The fault level for the Existing System with no Generation Addition1. For 3LG Bus fault at SEC 138 kV, Short Circuit MVA = 11452. For 3LG Bus fault at COM 138 kV, Short Circuit MVA = 5003. For 3LG Bus fault at SCG 138 kV, Short Circuit MVA = 545

The fault level for the Existing System with Proposed Generation Addition

1. For 3LG Bus fault at SEC 138 kV, Short Circuit MVA = 11952. For 3LG Bus fault at COM 138 kV, Short Circuit MVA = 5703. For 3LG Bus fault at SCG 138 kV, Short Circuit MVA = 610

The fault level contribution from the proposed IPP generation, in terms of itsimpact on the Transmission System, is not considered severe. IPP impact on the

fault duty of the system does not require any reinforcement.

4.3 Transient Stability Study

1L44 is a radial connection to the main transmission grid for all the generation in

the Clowhom Peninsula. When 1L44 is opened due to a fault, or due to a plannedoperation, all generators in the Clowhom Peninsula must stop generating. For

planned line outages, generators must be disconnected from the system before

opening the line. For forced outage, existing high speed line protection must trip

the breakers at COM and SCG. Since the tie between the new BRK substation andCOM is less than 200 meters, and BRK transformers have HV grounded wye, LV

delta configuration, existing 1L44 line protection can be modified to include

tripping of COM and the breaker at the entrance of the BRK substation. This willavoid the requirement and the cost of a Direct Transfer Trip for the IPP. However,

the IPP should have adequate protection for its equipment for such an event.

The swing centre is within the IPPs generator and out of step protection is

recommended.

For transient stability concerns, studies were performed to evaluate the impact on

the main system and on the IPP when there is a fault inside the IPP system or in

the Transmission System. The following scenarios were investigated, and

corresponding findings tabulated:

Description Stable

1 8 cycle fault on Bears 138 kV line between Upper and Lower Bearnear Lower Bear

*Yes

2 9 cycle fault on Bears 138 kV line between Upper and Lower Bear Yes


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near Lower Bear

3 10 cycle fault on Bears 138 kV line between Upper and Lower Bear

near Lower Bear

Yes

4 8 cycle fault on Bears 138 kV line between Lower Bear and BearStation near Bear station

*Yes


*Yes


No

7 12 cycle fault on Bears 138 kV line between Lower Bear and BearStation and near Bear station

No

8 8 cycle fault on 1L32 between SEC and Gibsons (GIB) near SEC Yes

9 9 cycle fault on 1L32 between SEC and GIB near SEC Yes

10 10 cycle fault on 1L32 between SEC and GIB near SEC No

11 12 cycle fault on 1L32 between SEC and GIB near SEC No

12 8 cycle fault on 1L35 between SEC and Malaspina (MSA) near SEC Yes

13 9 cycle fault on 1L35 between SEC and MSA near SEC No14 10 cycle fault on 1L35 between SEC and MSA near SEC No

15 12 cycle fault on 1L35 between SEC and MSA near SEC No

16 40 cycle fault on 1L32 near GIB No

17 40 cycle fault on 1L35 near Pender Harbor (PHR) No

18 6 cycle bus fault at SEC Yes



21 10 cycle bus fault at SEC No

*Yes Bear IPP generators will be lost, but COM and SCG remains stable

4.4 Protection Study

Assumptions:

BRK and COM share the same ground grid, and the overhead tie is notmore than 200 meter.

BRK transformers have grounded wye on the high side, and delta on thelow side.

Existing high speed line protection for 1L44 will isolate COM and SCG in theevent of a fault resulting in the opening of 1L44. This protection can be modified

to include the IPP by tripping the circuit breaker at the entrance to the new Bearstation (BRK). No direct transfer trip to the IPP is required.

4.5 Remedial Action Schemes

No generation shedding is required.

4.6 Black Start Capability

BCTC does not require black start capability for the Bear Creek Hydro IPP.


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5.0 Reinforcements and Upgrades

The required Transmission System upgrades for Bear Creek Hydro IPP

interconnection are described in the Bear Creek IPP Interconnection FacilityStudy, BCTC SPA Report SPA 2005-33.

6.0 Conclusions

6.1 The Bear Creek Hydro IPP interconnection was found to be technicallyfeasible.

6.2 Sections of 1L44 need to be upgraded to higher summer thermal ratings.

6.3 1L44 line protection needs to be modified to include tripping the BRKentrance circuit breaker in the event of a fault on 1L44.

6.4 No transient or temporary overvoltage problems are observed.


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Appendix

One-Line Diagram 1: Normal System before Bear Creek Hydro IPP


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One-Line Diagram 2: Normal System with Bear Creek Hydro IPP


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One-Line Diagram 3: System with Bear Creek Hydro IPP, 1L35 Out of Service


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One-Line Diagram 4: System with Bear Creek Hydro IPP, 1L32 Out of Service


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Machine Data

Salient Pole Generator (Quadratic Saturation on d-Axis) model GENSAL:

Upper Bear G1 Lower Bear G2Tdo 4.24 3.55

Tdo 0.07 0.07

Tqo 0.11 0.11

Inertia, H 2 2

Speed Damping D 1 1

Xd 1.88 1.8

Xq 1.74 1.7

Xd 0.299 0.31

Xd=Xq .199 0.2

X1 0.19 0.19

S(1.0) 0.194 0.685S(1.2) 0.194 0.685

Xd, Xq, Xd, Xd, Xq, X1, H and D are in pu, machine MVA base


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Machine Data

Simplified Excitation System model SEXS:

Upper Bear G1 Lower Bear G2TA/TB 1.0 1.0

TB 1.0 1.0

K 20 20

TE (sec) 0.5 0.5

Emin (pu on EFD base) -3.0 -3.0

Emax (pu on EFD base) 3.0 3


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Machine Data

Hydro Turbine-Governor model HGOV:

Upper Bear G1 Lower Bear G2

R, permanent droop 0.05 0.05

R, temporary droop 5 5

Tr, governor time constant 15 15

Tffilter time constant 0.04 0.04

Tg servo time constant 0.2 0.2

+/- VELM, gate velocity limit 0.07 0.07

Gmax maximum gate limit 1 1

Gmin Minimum gate limit 0 0Tw water time constant 3.5 3.5

At turbine gain 1.1 1.1

Dturb turbine damping 0 0

qNL, no load flow 0.08 0.08


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Stability Plot 1: 10 cycle fault on Bears 138 kV line between Upper and Lower Bear

near Lower Bear (3)


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Stability Plot 2: 9 cycle fault on Bears 138 kV line between Lower Bear and BearStation near Bear station (5)


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Stability Plot 3: 9 cycle fault on 1L32 between SEC and Gibsons (GIB) near SEC(10)


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Stability Plot 4: 8 cycle fault on 1L35 between SEC and Malaspina (MSA) nearSEC (8)


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Stability Plot 5: 9 cycle bus fault at SEC (11)


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Clowhom AC Conceptual Protection One-line Diagram:

~

COM

138 kV

1L4413CB1

~

~

T1

C/S(52L)

UPPER BEAR LAKE13 MVA

LOWER BEAR LAKE8.5 MVA

COM (BCTC)

BRK (IPP)

COM Conceptual AC ProtectionOne Line Diagram

BEAR CREEK HYDRO ProjectSketch # 1

B.J. Burk July 07 2005

21LS

21L

*

Notes:* Inidicates New Relay

1CVT1

*


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Control Diagram for Bear Station

DNP3.0 IED(provided by Bear Creek

Hydro IPP)

data from both UpperBear and Lower Bear

SIC

2 status

8 telemetry

LMC

DDC1

DataConcentrator

D20

ScopeStation:

DWG No SH R

BRK IPP

SK11 0

By:

Date: 24-June-

2005

G. Jang

SCC

SIC


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Control Diagram for Clowhom Generating Station

SIC

STIC

COMS223/T119

new relay alarms

4 new telemetry

ScopeStation:

DWG No SH R

COM

SK21 0

By:

Date: 08-July-

2005

G. Jang

New SEL-203X (at COM) 2 new relays

LMC

Edmonds(Remote Data Access)

BCH legacy protocol

SEL protocol

1 status

Documents

Bear Creek System Impact Study