a subsidiary of pinnacle west capital corporation€¦ · the following generation was added to the...

A subsidiary of Pinnacle West Capital Corporation

Interconnection Feasibility Study Report

APS Q88

FINAL

By

Arizona Public Service Company Transmission Planning

APS Contract No. 52235

September 2, 2010

Version 1 - 3

Prepared by Utility System Efficiencies, Inc.

Interconnection Feasibility Study APS: Q88

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Table of Contents 1. Executive Summary ................................................................................................................ 2 2. Study Assumptions ................................................................................................................. 5

2.1. Project Assumptions ......................................................................................................... 5 2.2. Case Modeling Assumptions - 2011 ................................................................................ 6

3. Power Flow Cases ................................................................................................................... 7 4. Study Methodology ................................................................................................................. 8

4.1. Power Flow Analysis ....................................................................................................... 8 4.2. Voltage Flicker Analysis .................................................................................................. 9 4.3. Short Circuit Analysis ...................................................................................................... 9

5. Study Results ........................................................................................................................ 10 5.1. Power Flow .................................................................................................................... 10 5.2. Voltage Flicker ............................................................................................................... 10 5.3. Short Circuit ................................................................................................................... 11 5.4. Mitigation ....................................................................................................................... 11

6. Cost Estimates ....................................................................................................................... 12 6.1. Interconnection Costs Estimate ...................................................................................... 12

Appendix A – Contingency List Appendix B – Power Flow Plots


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1. Executive Summary The Interconnection Customer (IC), submitted a Small Generator Interconnection Request (IR) to Arizona Public Service Company (APS) for their proposed Wind Energy Facility Project, located approximately one and one half miles from the Sugarloaf Substation, near Snowflake, Arizona. The Interconnection Customer (IC) plans to install 18.9 MW of wind generation. The proposed In-Service Date is December 31, 2010. The Project’s requested Point of Interconnection (POI) is the Sugarloaf Substation’s 69 kV bus. The Project is number 88 (Q88) in the APS generation interconnection queue. In accordance with Federal Energy Regulatory Commission (FERC) Small Generator Interconnection Procedures (SGIP), APS and Utility System Efficiencies, Inc (USE) performed an Interconnection Feasibility Study (IFeS) on Q88. The IFeS determined the following:

1. Preliminary identification of any thermal overloads or voltage limit violations resulting from interconnection of the Project.

2. Preliminary identification of any circuit breaker short circuit capability limits exceeded as a result of interconnection of the Project.

3. Preliminary list of facilities, a non-binding good faith estimate of cost responsibility, and a non-binding good faith estimated time to construct facilities necessary to interconnect the Project.

DISCLAIMER

Nothing in this report constitutes an offer of transmission service or confers upon the Interconnection Customer, any right to receive transmission service. APS and other interconnected utilities may not have the Available Transmission Capacity (ATC) to support the interconnection described in this report. It should also be noted that the results in this IFeS are dependent upon the assumed topology and timing of new projects in the area, which are subject to change.

Figure 1.1 shows a single line diagram of the Arizona 69 kV transmission system in the vicinity of the Project.


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Figure 1.1: Single Line Diagram of 69 kV in the Project Vicinity

The Project was studied under 2011 heavy summer conditions. The 2011 heavy summer scenario represents the time of interconnection of the Project. Assuming the generators have a +/- 0.95 pf capability, additional reactive compensation may not be required to produce an approximately net zero VAr flow from the Project at the POI for the N-0 condition. This should be reviewed in the System Impact Study when collector system data is available and the Project can be modeled in more detail.

RESULTS:

The results of the 2011 power flow analysis indicate that the Project did not trigger any new overloads or voltage violations in the Arizona, New Mexico, El Paso or WAPA R.M systems. Although there were pre-Project overloads and voltage violations, any incremental increases due to the addition of the Project were less than 1%.

Short circuit study results indicate that the existing transmission system breakers would not be overstressed by the interconnection of the Project. However, detail short circuit analysis would be needed to determine breaker sizes for the final interconnection plan.


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Energy Resource Interconnection cost and timeline estimates are listed on the table below:

Table 1.1: Summary of Project Interconnection Costs Facility Costs Timeline Network Upgrades $287,000 12 Months Q88 Trans. Provider's Interconnection Facilities $124,000 12 Months

Total $411,000 12 Months

As can be seen in Table 1.1 above, the total estimated completion time for interconnecting the Q88 project is 12 months. Therefore, the desired In-Service Date of December 31, 2010 cannot be met. APS and the Interconnection Customer must therefore discuss and mutually agree to a new and acceptable projected In-Service Date.


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2. Study Assumptions

2.1. Project Assumptions The following Project assumptions were used for this study: 1. The Project is a wind energy project with nine Suzlon S88 2.1 MW wind turbines generating

a total of 18.9 MW. The VAr capability for each unit is assumed to be +/- 0.95 pf. 2. The Project is located approximately one and one half miles from and interconnecting to the

Sugarloaf Substation 69 kV bus. 3. The requested In-Service Date is December 31, 2010. 4. An equivalent model was used in the study. It consists of a 1.5 mile gen-tie, a 69/34.5 kV

transformer, and the generation modeled as a single 18.9 MW generator at the 34.5 kV bus. 5. Collector system information was not provided. To simulate the losses of the 34.5 kV

collector system and 34.5/0.6 kV GSUs, a lagging pf of 0.98 was assumed, which was modeled as a load of 0 MW and 3.84 MVAr at the Project 34.5 kV bus.

6. The generator tie line was modeled as 1.5 miles of 795 AA with a continuous rating of 108 MVA. The positive sequence impedance of the line was modeled as R1pu=0.004125, X1pu=0.0195 and B1pu=0.000525 on a 100 MVA and 69 kV base.

7. The station transformer was modeled as one 69/34.5 kV transformer rated at 25 MVA with R = 0.005302 and X = 0.08483 on a 20 MVA base.

8. Reactive compensation was added at the Project’s 69 kV bus as necessary to generate approximately net zero VAr flow from the Project at the Point of Interconnection. In order to ensure the shunt capacitor can be properly tied into the APS protection system, the minimum 69 kV shunt capacitor size will be 7.2 MVAr; further increments of 3.6 MVAr may be added as needed.

The modeling of Q88 and its interconnection is depicted in Figure 2.1.

Figure 2.1: Q88 Project Model

69 kV 25 MVA69/34.5 kV

R=0.005302, X=0.08483

Base = 20 MVA

P = 0 MWQ = 3.84 MVArAssumed losses for collector system & GSUs (0.98 pf)18.9 MW

Sugarloaf 69 kV

POI Gen-tie

34 kV

Cap to produce ~ 0 VAr flow at POI


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2.2. Case Modeling Assumptions - 2011 The 2011 summer case was developed from the APS Planning Study Basecase sm11#16.sav, which was jointly built by the Arizona utilities. It includes the latest load forecast for 2011. The following generation was added to the case:

Abitibi at 25 MW Hahsknife at 63 MW Conley at 63 MW Q28 at 125 MW Q37 at 300 MW Q53 at 150 MW (modeled connected to the Cholla-PP 345 kV line)

Generation at Redhawk was reduced to accommodate the additional generation.


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3. Power Flow Cases The 2011 cases utilized in the power flow studies were developed from an APS Detailed Planning Study case (“sm11#16.sav”), which included modeling of the 69 kV sub-transmission system. The post-Project case was created by adding the Q88 Project interconnected to the Sugarloaf 69 kV bus. By setting the scheduled voltage at the Project generator to 1.02 pu, the VAr flow from the Project at the POI was approximately zero, so no additional VAr compensation was added at the Project 69 kV bus. (This should be reviewed in the System Impact Study when the Project can be modeled in more detail with collector system data and verified generator capabilities.) Note:

Although no additional VAr compensation was added at the 69kV bus, Q88 will be required to possess the capability of providing +/- 0.95 Power factor at the POI when call upon by APS.

A summary of case attributes is shown in the table below. Table 3.1: Project Power Flow Case Attributes

Year/Season 2011 Summer

Base Case Pre (MW)

Post (MW)

Path 50 Cholla-Pinnacle Peak 989 994 Path 54 Coronado West 1,184 1189 Sugarloaf 69/500 kV 69 84 Cholla 500/345 #1 193 196 Cholla 500/345 #2 197 199 Area 14 – Arizona Load 19,603 19,603 Losses 729 730 Gen 27,843 27,844 Interchange 7510 7510


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4. Study Methodology The Interconnection Feasibility Study consists of power flow, voltage flicker, and short circuit analysis in order to identify a preliminary list of facilities, a non-binding good faith estimate of cost responsibility and a non-binding good faith estimated time to construct facilities necessary to interconnect the Project. Table 4.1: Study Summary # Description 2011 1. Power flow √ 2. Flicker √ 3. Short Circuit Analysis √

4.1. Power Flow Analysis For normal conditions, automatic transformer taps, static VAr devices (SVD) and phase-shifting transformers (PST) were allowed to adjust in solving the power flow cases. For contingency simulations, the power flow analysis considers a snapshot in time where automatic transformer taps and SVDs are allowed to adjust, while PSTs remain fixed; in addition, a system swing bus balances the system during each contingency scenario. Areas 14 (Arizona), 10 (New Mexico), 11(El Paso) and 73 (WAPA R.M.) were monitored. Power flow analysis was performed using the NERC/WECC planning standards. Power flow analysis was used to evaluate thermal and voltage performance of the transmission system for NERC/WECC Category A normal (all elements in-service) conditions, and selected NERC/WECC Category B emergency (one element out of service) conditions. Category A (N-0) normal overloads are those that exceed 100% of normal ratings that occur with all facilities in service. Category B emergency overloads are those that exceed 100% of emergency ratings that occur due to a Category B contingency. All power flow analysis was conducted with version 17.0_04 of General Electric’s PSLF software. Reported normal thermal loading was limited to the condition where a modeled transmission component was loaded above 100% of the normal MVA rating (Rating 1 as entered in the power flow case), and the incremental increase in component loading, between pre-project and post-project, exceeded 1%. Reported emergency thermal loading was limited to the condition where a modeled transmission component was loaded over 90% of its appropriate emergency MVA rating (Rating 2 as entered in the power flow case), and the incremental increase in component loading, between pre-project and post-project, exceeded 1%. Reported normal voltage violations were limited to the conditions where per unit (pu) voltages were less than 0.95 or greater than 1.05 (less than 1.00 and greater than 1.10 for 500 kV buses). Reported emergency voltage violations were limited to the conditions where per unit voltages were less than 0.90 or greater than 1.10. In addition, only voltage deviations greater than 5%


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between the pre and post-contingency and a 1% increase in voltage deviation between the pre and post-project power flow cases were recorded.

4.2. Voltage Flicker Analysis Voltage flicker analysis was performed to determine if there were impacts from generation output variation on local area bus voltages. The analysis used typical PSLF solution parameters for N-0.

4.3. Short Circuit Analysis Short circuit analysis of the proposed generator interconnection(s) was performed by the APS Protection Department, using the CAPE program and parameters supplied by the IC. Fault duties were calculated for both single-phase-to-ground and three-phase faults at substation busses in the immediate surrounding area before and after the proposed generator installation.


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5. Study Results

5.1. Power Flow Power flow analysis was performed on the pre and post-Project power flow cases. The results were compared to determine the impacts caused solely by the addition of the Project and to identify the system reinforcements necessary to mitigate the adverse impacts. The pre and post-Project cases were evaluated for Category A (N-0 or all lines in service) conditions. Contingencies were then applied to the power flow cases. The list of contingencies simulated is provided in Appendix A. Selected power flow plots of the Category A scenarios are included in Appendix B

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Category A: N-0 All lines in Service Based on the results of the 2011 power flow analysis, there were no N-0 thermal overloads or voltage violations triggered by the Project. Category B: N-1 Contingencies The results of the 2011 power flow analysis showed no N-1 thermal overloads or voltage violations triggered by the Project. Note: Although there were pre-Project overloads and voltage violations, any incremental increases due to the addition of the Project were less than 1%. Closing the Showlow-Vernon 69kV line as part of the contingency eliminates the violations. The 2011 case shows that there is incremental flow onto Salt River Project (SRP)’s Cholla – Sugarloaf – Coronado 500 kV line of 16 MW. This incremental flow may or may not need to be mitigated, depending upon the delivery of the project. Potential mitigation of this inadvertent flow will need to be addressed in conjunction with SRP.

5.2. Voltage Flicker Table 5.1 shows the results of the voltage flicker analysis. No voltage changes greater than 1% were observed in the post project case.


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Table 5.1: 2011 Voltage Flicker

5.3. Short Circuit The results presented here assume a “worst-case” scenario, with all of the project’s generating units assumed on-line. For this initial FeS, short circuit analysis primarily focused on busses in the immediate vicinity of the interconnection. Table 5.2 provides a comparison of fault duties at several local busses for both the Pre-Project and Post-Project conditions. The summary Table also provides the minimum circuit breaker rating at each of these substations. Table 5.2: Short Circuit Results

Substation Base Case & Q28 With Q88 3 Ph. (kA)

X/R Ph-G (kA)

X/R 3 Ph. (kA)

X/R Ph-G (kA)

X/R Min. Brkr Rating -kA

Q88 69kV NA NA NA NA 8.1 16.4 8.2 13.0 As Required Q28 69kV 7.4 19.7 6.2 21.3 7.5 19.5 6.3 21.1 As Required Sugarloaf 69kV 9.6 35.9 11.0 32.8 9.8 35.5 11.3 32.4 40 Zeniff 69kV 8.1 10.2 5.0 7.1 8.2 10.1 5.1 7.1 40 Snowflake 69kV 4.9 6.6 3.7 5.0 4.9 6.6 3.7 4.9 40

As can be seen from Table 5.2, the interconnection of the project does not cause the existing substation breakers to exceed their minimum rating.

5.4. Mitigation As there were no criteria violations triggered by the Project found in the analysis, there is no mitigation plan of service proposed for the Q88 Project as a result of this IFeS.

Bus Voltage (pu) Voltage Deviation Voltage Deviation Voltage Deviation Voltage DeviationCHOLLA1 69.00kV 1.0283 1.0291 0.0008 1.0289 0.0006 1.0287 0.0004 1.0284 0.0001RC-WT 69.00kV 1.046 1.0462 0.0002 1.0462 0.0001 1.0461 0.0001 1.0461 0RC-W 69.00kV 1.0477 1.0478 0.0001 1.0478 0.0001 1.0477 0.0001 1.0477 0ZENIFF 69.00kV 1.0322 1.0324 0.0002 1.0324 0.0001 1.0323 0.0001 1.0323 0SGRLF 69.00kV 1.0365 1.0371 0.0006 1.037 0.0005 1.0368 0.0003 1.0366 0.0001SNOWFLAK 69.00kV 1.0255 1.0258 0.0003 1.0257 0.0002 1.0256 0.0002 1.0255 0SHOWLOW 69.00kV 1.0153 1.0155 0.0002 1.0155 0.0002 1.0154 0.0001 1.0153 0SHUMWAY 69.00kV 1.0207 1.0209 0.0003 1.0209 0.0002 1.0208 0.0002 1.0207 0BACON 69.00kV 1.0422 1.0423 0.0002 1.0423 0.0001 1.0422 0.0001 1.0422 0RC-ET 69.00kV 1.0472 1.0473 0.0002 1.0473 0.0001 1.0472 0.0001 1.0472 0RC-E 69.00kV 1.0484 1.0485 0.0001 1.0485 0.0001 1.0484 0.0001 1.0484 0WOODRUFF 69.00kV 1.0386 1.0391 0.0005 1.039 0.0004 1.0388 0.0002 1.0387 0.0001Q088 69.00kV 1.0373 1.0375 0.0003 1.0375 0.0003 1.0375 0.0002 1.0373 0.0001

100% Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation


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6. Cost Estimates The cost estimates represent good faith estimates necessary to interconnect to the system. The costs do not include any costs for new rights-of-way that may potentially be needed for some upgrades or for Transmission Line Siting activities that would need to be performed. The non-binding, good faith cost and time estimates are tabulated below.

6.1. Interconnection Costs Estimate High level interconnection cost estimates for the feasibility interconnection is tabulated below. Assumptions:

• Rough grading costs are not included in the estimate. • APS will construct, own and operate the facilities in the Sugarloaf substation and the

portion of 69 kV line from the Sugarloaf 69 kV bus up to the first structure outside the sub fence.

• Q88 will construct, own and maintain the 69 kV gen-tie from Sugarloaf substation to their collector station.

• Q88 will be responsible for providing a fiber optic communications path from the collector station to the Sugarloaf substation.

• All estimates are in 2010 dollars. Table 6.1 Q88 Project Cost Summary

Equipment Description Network Upgrades Transmission Provider's Interconnection Facilities

Q88 Ring Bus $287,000 $124,000

Q88 69kV Line Work $0 $0

Communications (Fiber Optic Cable)

$0 $0

Right of Way $0 $0 Subtotal $287,000 $124,000 Grand Total $411,000

The facilities identified in Table 6.1 above as Transmission Provider’s Interconnection Facilities would be the sole cost of the Interconnection Customer. Unlike Network Upgrades, these costs are not reimbursable.


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Table 6.2 Construction Time Estimates

Facility Schedule

Design Construction Q88 69 kV Ring Bus 6 Months 6 Months Q88 69 kV Line Work Not Applicable Not Applicable Communications Not Applicable Not Applicable Right of Way Not Applicable Not Applicable

Total 12 Months The summary provided in Table 6.2 above shows a total estimated completion time of 12 months. Therefore, the desired In-Service Date of December 31, 2010 cannot be met. APS and the Interconnection Customer must therefore discuss and mutually agree to a new and acceptable projected In-Service Date. Table 6.3 Network Upgrade Cost Estimates

Equipment Description Sugarloaf 69kV Ring Bus

Engineering and Design $81,600 Below Grade Construction $7,200 Above Grade Construction Labor (Steel, Bus, & Equipment) $25,200 Control/Relay Labor $18,000 Equipment/Relay/RTU/Security $155,000 Steel Structures $0 Communications (Fiber Optic Cable)

$0

69kV Line Right of Way $0 69kV Double Circuit $0 Land Services/Siting/Permit/Etc $0 Subtotal $287,000 Grand Total $287,000

*Network Upgrades Estimates: are anticipated to consist of the above listed $287,000 shown for Expansion to Sugarloaf for Q88, Control, Communications, and Relay Protection Requirements. Network Upgrades are typically repaid to the customer per FERC Rules, as transmission credits and/or repaid within a 20 year period.


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Table 6.4 Transmission Provider’s Interconnection Facilities Cost Estimates Equipment Description Q88 4-Element Ring Bus Engineering and Design $13,200 Below Grade Construction $10,000 Above Grade Construction Labor (Steel, Bus, & Equipment) $18,000 Control/Relay Labor $1,200 Equipment/Relay/RTU/Security $76,800 Steel Structures $4,800 Communications (Fiber Optic Cable)

$0

69kV Line Right of Way $0 69kV Line Work $0 Land Services/Siting/Permit/Etc $0 Subtotal $124,000 Grand Total $124,000

Figure 6.1 shows a single line diagram of the build-out for Q88’s interconnection facilities.

Figure 6.1: Single Line Diagram of Sugarloaf 69kV ring bus


A1

Appendix A

CONTINGENCY LIST


A2

List of Applied Contingencies:

Note: This list includes breaker-to-breaker outages and 69 kV breaker-to-tap, tap-to-tap and bus-to-bus “outages” in the electrical vicinity of the interconnection, per APS’ request.

1. N-1 CHOLLA1-LEROUX 69 kV Line 2. N-1 LEROUX –INDWELLS 69 kV Line 3. N-1 INDWELLS-JEDDITO 69 kV Line 4. N-1 JEDDITO-KEAMCNYN 69 kV Line 5. N-1 CHOLLA1-SC 69 kV Line 6. N-1 SC-SGRLF 69 kV Line 7. N-1 CHOLLA1-RC-WT 69 kV Line 8. N-1 RC-WT-ZENIFF 69 kV Line 9. N-1 ZENIFF-ABITIBTP 69 kV Line 10. N-1 SGRLF-ZENIFF 69 kV Line 11. N-1 ZENIFF-HEBER 69 kV Line 12. N-1 HEBERTP-ZENIFF 69 kV Line Close Showlow-Vernon 13. N-1 LINDEN-HEBERTP 69 kV Line Close Showlow-Vernon 14. N-1 LINDEN-SHOWLOW 69 kV Line Close Showlow-Vernon 15. N-1 PEAPS-SHOWLOW 69 kV Line Close Showlow-Vernon 16. N-1 SHOWLOW-SHUMWAY 69 kV Line Close Showlow-Vernon 17. N-1 SNOWFLAK-SHUMWAY 69 kV Line Close Showlow-Vernon 18. N-1 SGRLF-SNOWFLAK 69 kV Line 19. N-1 BACON-SNOWFLAK 69 kV Line 20. N-1 BACON-RC-ET 69 kV Line 21. N-1 RC-ET-RC-E 69 kV Line 22. N-1 RC-ET-WOODRUFF 69 kV Line 23. N-1 CHOLLA2-LEROUXTP 69 kV Line 24. N-1 LEROUXTP-WOODRUFF 69 kV Line 25. N-1 CHOLLA2-CHLCONST 69 kV Line 26. N-1 WINSLOW-CHLCONST 69 kV Line 27. N-1 WINSLOW-WINSLOWB 69 kV Line 28. N-1 WINSLOWB-BR1 69 kV Line 29. N-1 WINSLOW-LEUPPJCT 69 kV Line 30. N-1 SUNSHINE-LEUPPJCT 69 kV Line 31. N-1 PADRE-SUNSHINE 69 kV Line 32. N-1 RC-WT-RC-W 69 kV Line 33. N-1 CHOLLA1-RC-WT-ZENIFF 69 kV Line 34. N-1 ZENIFF -HEBERTP- LINDEN-SHOWLOW 69 kV Line (w/ and w/o closing Showlow-Vernon) 35. N-1 SNOWFLAK-SHUMWAY-SHOWLOW 69 kV Line (w/ and w/o closing Showlow-Vernon) 36. N-1 CHOLLA2-LEROUXTP- SNOWFLAK 69 kV Line 37. N-1 CHOLLA2-CHLCONST-WINSLOW 69 kV Line 38. N -1 WINSLOW-LEUPPJCT-COCONINO 69 kV Line 39. N-1 CHOLLA-LEUPP 230 kV Line 40. N-1 LEUPP-COCONINO 230 kV Line 41. N-1 SGRLF-CHOLLA 500kV Line (w/ and w/o SPS) 42. N-1 CORONADO-SGRLF 500 kV Line (w/ and w/o SPS)

Transformers

43. T-1 SGRLF 500/69 kV (w/ and w/o closing Showlow-Vernon + cap) 44. T-1 CHOLLA/CHOLLA1 230/69 kV 45. T-1 CHOLLA/CHOLLA2 230/69 kV 46. T-1 CHOLLA/CHOLLA2 345/69 kV 47. T-1 CHOLLA 345/230 kV

Project

48. N-1 Q88-SGRLF 69 kV Line


B1

Appendix B

POWER FLOW PLOTS


B2

Plot 1: Pre-Project (MW/MVAr)


B3

Plot 2: Post-Project (MW/MVAr)

a subsidiary of pinnacle west capital corporation€¦ · the following generation was added to the...

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