Q197 Generator Interconnection Project

A subsidiary of Pinnacle West Capital Corporation

System Impact Study

APS Contract No. 52453

Arizona Public Service Company Transmission Planning

March 28, 2013 Version 1.0 - Draft

Prepared by Utility System Efficiencies, Inc. Q197 System Impact Study APS Contract No. 52453

Q197 SYSTEM IMPACT STUDY

TABLE OF CONTENTS

EXECUTIVE SUMMARY ...... 3 1 Study Description and Assumptions ...... 6 1.1 Post Project Case Modeling...... 7 1.2 Dynamic Data ...... 12 1.3 Reliability Criteria ...... 12 1.3.1 Power Factor Criteria ...... 12 1.3.2 (Steady State) Power Flow Criteria ...... 12 1.3.3 Transient Stability Criteria ...... 12 2 Study Methodology ...... 14 2.1 Power Factor Requirements ...... 14 2.2 Power Flow ...... 14 2.3 Post-Transient ...... 15 2.4 Transient Stability ...... 16 3 Results and Findings ...... 18 3.1 Reactive Support ...... 18 3.2 Power Flow and Post-Transient Analysis ...... 18 3.3 Transient Stability Analysis ...... 20 3.4 Short Circuit / Fault Duty Analysis ...... 21 3.5 Results & Findings Summary ...... 22 4 Cost & Construction Time Estimates ...... 22

LIST OF APPENDICES Appendix A – Power Flow Diagrams Appendix B – List of Contingencies Appendix C – Transient Stability Modeling Appendix D – Transient Stability Plots Appendix E – WATS Voltage Criteria Violations

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Q197 System Impact Study APS Contract No. 52453

EXECUTIVE SUMMARY This section summarizes the System Impact Study (SIS) results for a proposed generation interconnection of 302 MW into the APS wholly owned part of the Moenkopi-Eldorado 500 kV transmission line. Specific details of the proposed interconnection’s impact on the surrounding transmission system can be found in the “Results and Findings” section of this report.

Disclaimer Nothing in this report constitutes an offer of transmission service or confers upon the Interconnection Customer (IC) 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 all results for the SIS are highly dependent upon the assumed topology and timing of new projects in the vicinity of the interconnection, which are subject to change.

Background: APS received a valid large generator interconnection request for a proposed interconnection to the APS wholly owned part of the Moenkopi – Eldorado 500 kV line. On behalf of, and with the oversight of APS, Utility System Efficiencies, Inc. (USE) performed a SIS under the APS Tariff. The interconnection request was assigned queue position #197. The Applicant has proposed to add a hybrid wind/solar photo-voltaic generation with a maximum net output of 302 MW, connecting directly into the Moenkopi – Eldorado 500 kV line at the end of the fourth quarter of 2013(unachievable).

Figure E.1 illustrates the proposed interconnection and nearby transmission facilities.

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Q197 System Impact Study APS Contract No. 52453

FOUR CORNERS NAVAJO

(to Crystal)

MOENKOPI (345kV)

(to SCE Eldorado) 500kV

Q197 Q36, ER Q62, ER

(34.5kV) (230kV) New Wind/Solar (230kV) Gen

(302MW) New Wind Gen New Wind Gen CEDAR MT. (1000MW) (500MW)

Q196 Q113

(34.5kV) (34.5kV)

YAVAPAI DUGAS New Wind/Solar Wind Gen Gen (100MW) MORGAN (361MW) (to Pinn. Peak)

(to Mead) WESTWING

(to Sun Valley 2016) (from Palo Verde)

Figure E-1. Q197 and Nearby Transmission Facilities

This SIS applied the machine parameters and characteristics provided by the Applicant.

Studies consisted of computer-based power flow, post-transient, transient stability, and short-circuit/fault duty analyses. This study modeled the proposed generation interconnection under anticipated 2013 summer peak conditions. Select contingencies which stressed the transmission system were simulated. Power flow, transient stability, and post-transient results were monitored for the NSTS facilities immediately adjacent to the Point of Interconnection (POI) and other neighboring systems.

System performance criteria used in the study: The criteria applied in this study are consistent with NERC/WECC Reliability Criteria. For more detailed information on the criteria used for each analysis see section 1.3 “Reliability Criteria.”

The APS Open Access Transmission Tariff (OATT) policy regarding power factor requires all Interconnection Customers, with the exception of wind generators, to maintain an acceptable power factor (typically near unity) at the POI, subject to system conditions. The APS OATT also requires

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Q197 System Impact Study APS Contract No. 52453

Interconnection Customers to be able to achieve +/- 0.95 power factor at the POI, with the maximum "full- output" VAR capability available at all output levels for the PV component. Furthermore, APS requires Interconnection Customers to have dynamic voltage control (operational time of less than 5 seconds) and maintain the voltage as specified by the transmission operator within the limitation of +/- 0.95 power factor, as long as the Project is online and generating. If the Project’s equipment is not capable of this type of response, a dynamic reactive device will be required. APS has the right to disconnect the Project if system conditions dictate the need to do so in order to maintain system reliability.

Results: The results of the SIS indicate that the addition of Q197 resulted in no reliability violations or overstressed breakers under normal conditions or following any outage condition in the 2013 Heavy Summer time frame. There were sensitivity cases (maximum path stressing) which had negative impacts but these can be mitigated by post contingency operating procedures to remove the IC, or generation re-dispatching to demonstrate path rating preservation (Path 49). The operating procedures will be to remove the IC when Path 51 loading is above 2,500 MW and then loss of the Navajo-Dugas and Yavapai-Westwing lines occur. The Moenkopi – Cedar Mountain series capacitors would also need to be bypassed.

When the IC is connected radially to either Moenkopi or Eldorado, there is a possibility of SSR impacts to the IC. It is recommended that the IC have studies performed to evaluate potential impacts. The series capacitors in the radial line could be bypassed as an assist to the IC.

An output of 302 MW requires a minimum of +/-99.2 MVAR capability at the POI to meet the +/-0.95 power factor requirement. VAR requirements beyond the specified capabilities of the generation components are necessary. An additional +/- 33.8 MVAR is necessary for a wind only dispatch. An additional +/- 3.8 MVAR is necessary for a solar only dispatch. For the condition when solar is at the maximum and wind is at maximum, the shortfall is +/- 46.7 MVAR.

The addition of the 300 MW IC project will increase flows south of the project into Westwing by approximately 80-130 MW. The incremental flow on the northern EOR lines will be in the range of 100- 170 MW, while the reduction in flow on the southern EOR lines will be the same 100-170 MW.

Table 1.1 Summary of Project Interconnection Cost Facility Costs ($M) Timeline Network Upgrades $18.7 21 Months Q197 Trans. Provider's $1.1 12 Months Interconnection Facilities Grand Total $19.8 21 Months

The total estimated completion time for interconnecting the Q197 project is 21 months. Therefore, the desired In-Service Date of the end of the fourth quarter of 2013 cannot be met. APS and the Interconnection Customer must discuss and mutually agree to a new and acceptable projected In-Service Date.

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1 Study Description and Assumptions This section of the report provides details pertaining to the power flow case development and an overview of the major study assumptions. All power flow, transient stability and post-transient study work was completed using General Electric’s Positive Sequence Load Flow (GE-PSLF), version 17.0_06.

The study used multiple starting base cases. The main study used the 2015 WECC approved planning case “15hs2a.sav”. The stressed EOR study used a case provided by APS/SCE. The stressed Southern Navajo study used a path rating case provided by APS. The light loading study used the 2012 WECC approved planning case “12lw2a.sav”. All the cases were reviewed by the WATS membership and comments were incorporated into the final base cases.

Pre- and post-project base cases were developed. The new generation was offset with the Palo Verde (PV) generation group for the Arizona dispatch and available SCE and LADWP for the California dispatch.

Generation assumed On-line as a sensitivity The following nearby generation interconnection requests ahead in the APS/ANPP queues were modeled in the power flow, post-transient, transient stability, and short-circuit analyses.  APS Q062: 500 MW at Moenkopi 500 kV as an ER in 2015 o Offset 50% output of the project in AZ with generation in Phoenix Metro o Offset 39% output of the project in SCE o Offset 11% output of the project in LADWP  APS Q113: 100.8 MW at Cedar Mountain 500 kV as a NR in 2012 o Offset output of the project in AZ with Hassayampa area generation  ANPP Q2 (Block 1): 175 MW at Hassayampa 500 kV in 2013 o Offset output of the project in AZ with Hassayampa area generation Transmission Project Assumptions The following transmission facilities were modeled in the power flow, post-transient, transient stability, and short-circuit analyses.  Sunrise Power Link (I.V. – Central 500 kV Line)  Navajo South (Path 51) Capacitor Upgrades  Delaney 500 kV Substation  Morgan 500 kV Substation (Navajo – Westwing 500 kV Line)  Morgan – Pinnacle Peak 500 kV Line  Delaney – Palo Verde 500 kV Line  ONE Nevada Line (Robinson – Harry Allen 500 kV) with one (1) Northwest 500/230 kV Transformer

Navajo Generation 7% Margin The Navajo Generation 7% margin case is used to reaffirm the transient stability performance for N-1 contingencies. The 7% margin does not apply for N-2 contingencies. The 7% increase in Navajo output was offset by a corresponding decrease in Four Corners generation.

High East-of-River (9300 MW) The high East-of-River case is used to determine the project’s impact on the EOR path. The pre-project case is stressed to the point where the Eldorado – Moenkopi series capacitor loading was near 100% for loss of the Navajo – Crystal 500 kV transmission line. The new projects were then added and the path was returned to the original flow by way of generation re-dispatch.

High Southern Navajo (2400 MW) The high Southern Navajo case is used to determine the project’s impact on the Southern Navajo path. The pre-project case is stressed to the point where the Yavapai – Willow Lake 230 kV transmission line was near 100% loading for loss of the Navajo – Dugas and Yavapai – Westwing 500 KV transmission lines. The new projects were then added and the path was returned to the original flow by way of generation re-dispatch.

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Light Load (Off-peak) The light load case is used to determine the project’s impact on the transmission system during light loading conditions such as a light winter scenario.

The additional modifications described below were then used to develop the SIS base cases.

All Cases: Base case changes 1) Cedar Mountain 500 kV substation was added. 2) Incorporated comments from Nevada Energy. 3) Incorporated comments from Salt River Project. 4) Incorporated comments from WAPA. 5) Incorporated comments from SCE. 6) Modified APS system based on feedback from APS planning engineers.

1.1 Post Project Case Modeling Request #197 is represented in the power flow model as 2x100.8 and 1x50.4 MW wind generators operated at +/-0.95 power factor (+/-33.0 MVAR capability and +/-16.6 MVAR per unit) connected to a 0.69 kV bus and 1x50 MW solar generators operated at +/-0.95 power factor (+/- 16.43 MVAR capability per unit) connected to a 0.48 kV bus. Transformers step the voltage up from 0.69 kV and 0.48 kV to a common 34.5kV bus. Two (2) transformers step the voltage up from 34.5 kV to 69 kV. The project is connected to the Moenkopi – Eldorado 500 kV line, 40 miles from Moenkopi. Figure 1-1 represents the Q197 power flow model.

Moenkopi 500 kV Eldorado 500 kV

40 miles 176 miles

500 kV

R=0.0028 R=0.0028 X=0.0700 X=0.0700 34.5 kV

R=0.0060 R=0.0060 R=0.0060 R=0.0060 X=0.0600 X=0.0600 X=0.0600 X=0.0600

0.690 kV 0.690 kV 0.690 kV 0.480 kV

Pmax=100.8 MW Pmax=100.8 MW Pmax=50.4 MW Pmax=50.0 MW Qrange=+/-33.0 MVAR Qrange=+/-33.0 MVAR Qrange=+/-16.6 MVAR Qrange=+/-16.43 MVAR

Figure 1-1: Q197 Power Flow Model

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Power scheduled to Palo Verde  Mesquite generation was reduced to offset the interconnection for Arizona dispatch.  SCE & LADWP generation was reduced to offset the interconnection for California dispatch.

Power flow diagrams of the transmission system along with the new generation interconnection are provided in Appendix A. Table 1.2 summarizes the case attributes for each scenario.

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Table 1.2 2013 Case Attributes Post- Post- Post- Post- Post- Project, Post- Project, Project, Project, Project, Q197 Project, Major Path/Branch Pre- Q196/197 Q196/197 Q196/197 Q197 AZ Q197 Flows Project AZ-CA AZ CA AZ Wind AZ Solar Path 46 WOR 6,377 6,642 6,363 6,915 6,368 6,369 6,375 Path 49 EOR 3,823 4,098 3,822 4,374 3,817 3,818 3,823 Navajo-Crystal 500 kV (@Navajo) 874 1,024 994 1,053 950 937 888 Eldorado-Q197-Moenkopi 500 kV (@Q197) 800 922 886 958 802 802 803 EOR Northern Sum 1,674 1,946 1,880 2,011 1,751 1,739 1,691 EOR Northern Incremental 272 206 337 77 65 17 Navajo-Dugas 500kV (@Navajo) 685 799 826 772 759 748 702 Moenkopi-Cedar Mountain/Q196 500kV (@Cedar Mountain) 623 486 519 453 753 734 652 So. Navajo (Path 51) Sum 1,308 1,285 1,345 1,226 1,512 1,481 1,355 So. Navajo Incremental -389 -329 -448 -162 -193 -319 So. Navajo @ Westwing 84 -127 -178 -76 -64 -37 80 So. Navajo @ Westwing Incremental -211 -262 -160 -148 -121 -4 Yavapai-Westwing 500kV (@Westwing) -378 -522 -554 -491 -494 -476 -402 Yavapai-Willow Lake 230 kV (@Yavapai) 148 160 160 160 157 156 152 Perkins-Mead 500 kV (@Perkins) -102 -111 -174 -47 -127 -124 -111 Navajo-Moenkopi 500kV (@Navajo) 678 414 417 411 528 551 646 Moenkopi-Four Corners 500kV (@Four Corners) 761 707 700 713 740 747 775 N.Gila-Imperial Valley 500kV (@N.Gila) 1,276 1,284 1,243 1,325 1,262 1,264 1,275 Hassayampa-N. Gila #1 500kV (@Hassayampa) 1,438 1,447 1,402 1,491 1,424 1,426 1,438 Palo Verde-Colorado River #1 500kV (@Colorado River) -973 -987 -896 -1,077 -941 -946 -970 Control Area Information AZ Load 21,784 21,784 21,777 21,784 21,784 21,784 21,784 AZ Losses 578 605 606 605 596 595 594 AZ Generation 27,983 28,311 28,004 28,612 28,001 28,000 27,999 AZ Interchange 5,620 5,922 5,621 6,223 5,621 5,621 5,621 IID Generation 1,237 1,236 1,236 1,236 1,236 1,236 1,236 IID Imports 212 212 212 212 212 212 212 SDG&E Generation 3,482 3,482 3,481 3,484 3,481 3,482 3,482 SDG&E Interchange -2,021 -2,021 -2,020 -2,021 -2,021 -2,020 -2,021 SCE Generation 19,549 19,314 19,544 19,085 19,545 19,546 19,546 SCE Interchange -6,683 -6,918 -6,683 -7,152 -6,683 -6,682 -6,683 LADWP Generation 5,493 5,435 5,499 5,377 5,496 5,495 5,493 LADWP Interchange -1,978 -2,044 -1,978 -2,110 -1,978 -1,978 -1,977 Case 1 2 3 4 8 9 10

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Post- Post- Post- Pre- Project, Pre- Project, Pre- Project, Project, w/Q62/ Project, Q196/197 Project, Q196/197 Major Path/Branch Flows w/Q62 196/197 (P51) (P51) (P49) (P49) Path 46 WOR 6,602 6,866 -383 -99 9,014 8,983 Path 49 EOR 4,063 4,338 -1,863 -1,566 9,318 9,326 Navajo-Crystal 500 kV (@Navajo) 960 1,109 135 312 1,516 1,593 Eldorado-Q197-Moenkopi 500 kV (@Q197) 952 1,074 -103 26 1,667 1,637 EOR Northern Sum 1,912 2,183 32 338 3,182 3,230 EOR Northern Incremental 271 306 48 Navajo-Dugas 500kV (@Navajo) 759 873 1,136 1,271 -8 67 Moenkopi-Cedar Mountain/Q196 500kV (@Cedar Mountain) 758 620 1,258 1,140 -145 -390 So. Navajo (Path 51) Sum 1,517 1,494 2,395 2,411 -153 -323 So. Navajo Incremental -23 16 -170 So. Navajo @ Westwing -65 -275 -442 -670 480 463 So. Navajo @ Westwing Incremental -210 -228 -17

Yavapai-Westwing 500kV (@Westwing) -497 -639 -834 -991 195 171 Yavapai-Willow Lake 230 kV (@Yavapai) 158 171 141 155 89 90 Perkins-Mead 500 kV (@Perkins) -116 -125 -1,328 -1,342 1,541 1,525 Navajo-Moenkopi 500kV (@Navajo) 517 254 553 341 325 322 Moenkopi-Four Corners 500kV (@Four Corners) 706 652 612 532 1,232 639 N.Gila-Imperial Valley 500kV (@N.Gila) 1,286 1,294 561 567 1,584 1,578 Hassayampa-N. Gila #1 500kV (@Hassayampa) 1,449 1,457 714 719 1,769 1,763 Palo Verde-Colorado River #1 500kV (@Colorado River) -991 -1,006 917 908 -2,353 -2,334 Control Area Information AZ Load 21,780 21,780 22,190 22,190 16,307 16,307 AZ Losses 614 644 714 750 548 494 AZ Generation 28,265 28,596 21,443 21,779 27,736 27,571 AZ Interchange 5,870 6,172 -1,461 -1,161 10,881 10,771 IID Generation 1,237 1,236 1,133 1,133 890 890 IID Imports 212 212 -128 -128 469 469 SDG&E Generation 3,482 3,483 2,045 2,044 2,122 2,122 SDG&E Interchange -2,021 -2,021 -2,202 -2,202 -2,035 -2,035 SCE Generation 19,359 19,123 19,939 19,700 9,749 9,856 SCE Interchange -6,877 -7,113 -2,833 -3,067 -5,026 -4,916 LADWP Generation 5,446 5,390 7,213 7,145 3,598 3,604 LADWP Interchange -2,033 -2,099 283 217 -1,237 -1,236 Case 11 12 13 14 15 16

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Post- Pre- Post- Pre- Project, Project, Project, Project, Q196/197 Light Q196/197 Major Path/Branch Flows Nav7Pct Nav7Pct Load Light Load Path 46 WOR 6,387 6,651 6,057 6,322 Path 49 EOR 3,847 4,123 3,582 3,853 Navajo-Crystal 500 kV (@Navajo) 911 1,056 1,080 1,224 Eldorado-Q197-Moenkopi 500 kV (@Q197) 815 939 1,037 1,152 EOR Northern Sum 1,727 1,995 2,117 2,376 EOR Northern Incremental 268 259 Navajo-Dugas 500kV (@Navajo) 726 833 503 614 Moenkopi-Cedar Mountain/Q196 500kV (@Cedar Mountain) 654 504 415 274 So. Navajo (Path 51) Sum 1,380 1,337 919 888 So. Navajo Incremental -43 -31 So. Navajo @ Westwing 71 -152 -289 -521 So. Navajo @ Westwing Incremental -223 -232

Yavapai-Westwing 500kV (@Westwing) -400 -534 -344 -486 Yavapai-Willow Lake 230 kV (@Yavapai) 152 161 132 142 Perkins-Mead 500 kV (@Perkins) -117 -122 342 339 Navajo-Moenkopi 500kV (@Navajo) 768 515 654 398 Moenkopi-Four Corners 500kV (@Four Corners) 717 638 816 741 N.Gila-Imperial Valley 500kV (@N.Gila) 1,274 1,281 831 841 Hassayampa-N. Gila #1 500kV (@Hassayampa) 1,437 1,444 480 485 Palo Verde-Colorado River #1 500kV (@Colorado River) -968 -981 -670 -688 Control Area Information AZ Load 21,784 21,784 11,707 11,707 AZ Losses 585 599 320 333 AZ Generation 27,989 28,305 17,927 18,241 AZ Interchange 5,620 5,922 5,901 6,202 IID Generation 1,236 1,236 784 784 IID Imports 212 212 454 454 SDG&E Generation 3,482 3,482 1,228 1,229 SDG&E Interchange -2,021 -2,021 -1,001 -1,000 SCE Generation 19,546 19,313 10,207 9,979 SCE Interchange -6,683 -6,918 -1,528 -1,763 LADWP Generation 5,494 5,437 2,929 2,876 LADWP Interchange -1,978 -2,044 90 23 Case 17 18 19 20

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1.2 Dynamic Data Appendix C provides the transient stability dynamic model(s) used in this study, and the details of these assumptions. Modeling for the new generation utilized machine characteristics provided by the Applicant. Stability plots of the flat run and select disturbance simulations are provided in Appendix D.

Dynamic Data File

1. Dynamic data files “15hs21.dyd” and “12lw2a.dyd” were obtained with the base cases from the WECC website. Dynamic data files for the High EOR and High S.Navajo were obtained from APS planning. 2. Representation of the APS Q113 model was added. 3. Representation of the ANPP Q2 model was added. 4. Representation of the APS Q62 model was added.

1.3 Reliability Criteria In general, an evaluation of the system reliability investigates the system’s thermal loading capability, voltage performance (not too high or low), and transient stability (the system should not oscillate excessively and generators should remain synchronized). The evaluation of these criteria must be conducted for credible ‘emergency’ conditions, such as loss of a single- or double-circuit line, a transformer, or a generator. Performance of the transmission system and neighboring Control Areas were measured against the Western Electricity Coordinating Council (WECC) Reliability Standards and the North American Electric Reliability Corporation (NERC) Planning Standards described in the following subsections. The criteria for Category A (TPL-001, “All lines in service”), Category B (TPL-002, single element outage), and Category C (TPL-003, multiple element outage) conditions were explicitly applied both internally (within APS system) and to external Control Areas.

1.3.1 Power Factor Criteria The study applies APS power factor criteria, which states that a generator must be capable of providing dynamic reactive support within the range of +/-0.95 power factor at the POI.

1.3.2 (Steady State) Power Flow Criteria Normal conditions  All line loading must be less than 100% of the continuous (normal) thermal ratings.  All transformer loading must be less than 100% of the continuous (normal) ratings. Contingency Conditions  For any contingency, no transmission element will be loaded above the emergency rating.  Depending upon the type of analysis and applied case/sensitivity, applicable criteria for system performance will be identified. In some instances, resulting local circuit overloads and/or voltage deviations may be deemed acceptable per local criteria; as long as the local system’s post- contingency performance does not result in cascading outages.  Established loading limits and voltage performance for other neighboring utilities will be monitored.  Voltage deviations at any bus must be no more than 5% for N-1 contingencies and no more than 10% for N-2.

1.3.3 Transient Stability Criteria The SIS applies reliability criteria contained within the WECC disturbance-performance table of allowable effects on other systems. Table 1.3 and Figure 1-2 are excerpts from the WECC Reliability Criteria.

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Table 1.3 WECC Disturbance-Performance Table of Allowable Effects on Other Systems Outage Frequency Associated with the NERC and WECC Transient Voltage Dip Minimum Transient Post-Transient Voltage Performance Categories Standard Frequency Standard Deviation Standard Category (outage/year) A Not Applicable Nothing in addition to NERC System normal Not to exceed 25% at load buses or 30% at B Not below 59.6Hz for 6 non-load buses. Not to exceed 5% at any One element  0.33 cycles or more at a load Not to exceed 20% for bus. out-of-service bus. more than 20 cycles at load buses. Not to exceed 30% at C any bus. Not below 59.0Hz for 6 Two or more Not to exceed 10% at 0.033 – 0.33 Not to exceed 20% for cycles or more at a load elements any bus. more than 40 cycles at bus. out-of-service load buses. D Extreme multiple- < 0.033 Nothing in addition to NERC element outages

Figure 1-2. NERC/WECC Voltage Performance Parameters

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2 Study Methodology This section summarizes the methods used to derive the power flow, post-transient, and transient stability results. Appendix B details the contingencies run for the study.

2.1 Power Factor Requirements The APS Open Access Transmission Tariff (OATT) policy regarding power factor requires all Interconnection Customers, with the exception of wind generators, to maintain an acceptable power factor (typically near unity) at the Point of Interconnection (POI), subject to system conditions. The APS OATT also requires Interconnection Customers to be able to achieve +/- 0.95 power factor at the POI, with the maximum "full-output" VAR capability available at all outputs. Furthermore, APS requires Interconnection Customers to have dynamic voltage control (operational time of less than 5 seconds) and maintain the voltage as specified by the transmission operator within the limitation of +/- 0.95 power factor, as long as the Project is online and generating. If the Project’s equipment is not capable of this type of response, a dynamic reactive device will be required. APS has the right to disconnect the Project from the power grid if system conditions dictate the need to do so in order to maintain system reliability.

The method for determining whether or not the generator meets these requirements is to first record the pre-project POI bus voltage. Next, model the generator with zero reactive capabilities at full output. Any shunt devices are turned off. Two synchronous condensers are added to the case with infinite reactive capability. One is at the terminal bus of the unit regulating the bus voltage to 1.0 pu. The other is one bus away from the POI regulating the POI to the pre-project voltage level. The amount of plant losses can be determined by recording the MVAR flow at the POI and adding that to the sum of the synchronous condenser output. Based on the maximum output of the plant, determine the minimum reactive capabilities required to meet the +/-0.95 power factor range. The sum of the two numbers determines the maximum amount of reactive support the project must provide.

2.2 Power Flow Power flow analysis considers a snapshot in time where the transformer tap changers, SVDs and, the phase shifters have not adjusted, and the system swing bus balances the system during each contingency scenario. All power flow analysis was conducted with version 17.0_06 of General Electric’s PSLF/PSDS/SCSC software. Power flow results were monitored and reported for APS and other neighboring systems, including TEP, WAPA, SRP and SCE.

Traditional power flow analysis was used to evaluate the thermal and voltage performance of the system under Category A (TPL-001, all elements in service), Category B (TPL-002, N-1, single contingency), and Category C (TPL-003, N-2 multiple element) conditions. The applicable WECC reliability planning criteria is listed below.

 Changes in bus voltages from pre- to post-contingency must be less than 5% for single contingencies.  All equipment loadings must be below their normal ratings under normal conditions.  All equipment loadings must be below their emergency ratings for all contingencies.  Depending upon the type of analysis and applied case/sensitivity, applicable criteria for system performance will be identified. In some instances, resulting local circuit overloads and/or voltage deviations may be deemed acceptable per local criteria; as long as the local system’s post- contingency performance does not result in cascading outages.

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Thermal loading was reported when a modeled transmission element was loaded over 98% of its appropriate MVA rating modeled in the power flow database and when the incremental change in loading, between Pre-Project and Post-Project, exceeded 1%.

Transmission voltage violations for Category A (TPL-001, no contingency) conditions are reported where per unit voltages were less than 0.95 or greater than 1.05. For Category B outages (TPL-002, N-1) the voltage violations are reported when the post-contingency voltage deviation was greater than 5%. For Category C outages (TPL-003, N-2) the voltage violations are reported when the post-contingency voltage deviation was greater than 10%.

2.3 Post-Transient Post-transient analysis determines if the voltage deviations at critical buses meet the maximum allowable voltage dip criteria and if any transmission elements exceed their maximum rating for selected Category B (TPL-002, N-1) disturbances. This snapshot focuses on the first few minutes following an outage where the transformer tap changers, the phase shifters, and SVDs have not adjusted, and all of the system generation reacts by governor control to balance the system during each contingency scenario. All loads are modeled as constant power during the post-transient time frame. Generator VAR limits will be modeled as a constant single value for each generator since the reactive power capability curve will not be modeled in the power flow program. Alpha min and Gamma min of the PDCI and IPPDC will be adjusted to 5 degrees and 13 degrees, respectively. Shunt capacitors (132 MVAR) at Adelanto and Marketplace will be used if the post-transient voltage deviation exceeds 5% at those buses.

The Western Arizona Transmission System Task Force (WATS) bus voltage criteria, as shown in Table 2.1, was also used to flag potential voltage violations.

Table 2.1 WATS Voltage Criteria Minimum Arizona, Southern Nevada and Southern California Bus Voltage Limits (525kV base) Pre-Outage Post-Disturbance Bus Comment Min. Volt (p.u.) Min. Volt (p.u.) Adelanto 500kV 525kV 515kV Sylmar 230kV Flag if < 0.99 0.95 DWP 1.00 0.95 NPCO 230kV Flag if < 0.985 0.90 NPCO 500kV Flag if < 500kV 488kV Palo Verde 500kV 525kV 525kV 1 SCE 230kV Flag if < 0.95 0.90 SCE 500kV Flag if < 518kV 483kV SDG&E 230kV 0.95 0.90 SDG&E 500kV 499kV 472.5kV North Gila 500kV (1.0 pu) 500kV (1.0 pu) Westwing 230kV Flag if < 1.03 0.95 Blythe 161kV Flag if < 0.95 0.91

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MWD Flag if < 0.9875 0.95 Arizona 230 kV 1.00 0.95 WAPA >=300kV Flag if < 1.00 0.95 WAPA < 300kV Flag if < 0.99 0.95 SRP 230kV 0.99 0.95 SRP 500kV 500kV 500kV

1) Palo Verde Pre-outage Vmax = 535kV

2.4 Transient Stability Transient stability analysis is a time-based simulation that assesses the performance of the power system during (and shortly following) a contingency. Transient stability studies were performed to verify the system stability following a critical fault on the system. Prior to finalization of the power flow and dynamic data set, a flat–run and bump test were run to ensure true power system behavior was not masked by any remote dynamic modeling anomalies.

Transient stability analysis was performed based on WECC Disturbance-Performance Criteria for selected system contingencies. Initial transient stability contingencies were simulated out to 11 seconds to ensure a damped system performance. All simulated faults were assumed to be three-phase. Table 2.1 identifies the breaker clearing times for faults on different voltage levels.

Table 2.1 Breaker Clearing Times Breaker Voltage Level clearing times 230/345 kV 5-cycles 500 kV 4-cycles

All transient stability simulations were conducted using version 17.0_06 of General Electric’s PSLF/PSDS/SCSC software.

The Worst Condition Analysis (WCA) tool, available in the PSDS software package, tracks and records the transient stability behavior of all output channels contained within the binary output file of a transient stability simulation. The monitoring of channel output was initiated two cycles after fault clearing, to ensure that all post-fault stability behavior would be captured. System damping was assessed visually with the aid of stability plots.

Parameters Monitored to Evaluate System Stability Performance:

Rotor Angle Rotor angle plots provide a measure for determining how the proposed generation unit would swing with respect to other generating units in the area. This information is used to determine if a machine would remain in synchronism or go out-of-step from the rest of the system following a disturbance.

Bus Voltage

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Bus voltage plots, in conjunction with the relative rotor angle plots, provide a means of detecting out-of-step conditions. The bus voltage plots are useful in assessing the magnitude and duration of post-disturbance voltage dips and peak-to-peak voltage oscillations. Bus voltage plots also give an indication of system damping and the level to which voltages are expected to recover in the steady state conditions.

Bus Frequency Bus frequency plots provide information on magnitude and duration of post-fault frequency swings with the new project(s) in service. These plots indicate the extent of possible over- frequency or under-frequency, which can occur due to an area’s imbalance between load and generation.

Other plotted Parameters  Generator Terminal Voltage  Generator Rotor Speed

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3 Results and Findings This section provides the results obtained by applying the previous assumptions and methodology. It illustrates all findings associated with the power flow, post-transient, and transient stability.

3.1 Reactive Support The project is required to meet the minimum power factor capability under all operating conditions. Three scenarios were analyzed that model the possible operating conditions. The project must be able to achieve +/-0.95 power factor at the point of interconnection when only the wind portion is online, only solar portion is online, and the solar portion is at full output with the remaining capacity made up with wind.

All Wind No Solar Power Factor Capability (252 MW) The project does not satisfy the minimum power factor requirement when only the wind portion of the project is operating. The wind turbines online at 252 MW require a minimum of +/-82.8 MVAR capability at the POI to meet the +/-0.95 power factor requirement. The calculated plant losses are 33.6 MVAR. The aggregated wind turbine dynamic capability is +/-82.6 MVAR. This results in 49 MVAR of capability at the POI. An additional +/- 33.8 MVAR of reactive support is required to offset the internal plant losses and meet the APS power factor requirement. The deficiency can be made up by switched capacitor banks.

All Solar No Wind Power Factor Capability (50 MW) The project does not satisfy the minimum power factor requirement when only the solar portion of the project is operating. The solar inverters online at 50 MW require a minimum of +/-16.43 MVAR capability at the POI to meet the +/-0.95 power factor requirement. The calculated plant losses are 3.8 MVAR. The aggregated solar inverter dynamic capability is +/- 16.43 MVAR. This results in 12.63 MVAR of capability at the POI. An additional +/-3.8 MVAR of reactive support is required to offset the internal plant losses and meet the APS power factor requirement. The deficiency can be made up by switched capacitor banks.

Full Solar +Full Wind (50 MW + 252 MW) The project does not satisfy the minimum power factor requirement when the solar portion of the project is operating at full output (50 MW) with the wind operating at full output (252 MW). The combined output of 302 MW requires a minimum of +/-99.23 MVAR capability at the POI to meet the +/-0.95 power factor requirement. The calculated plant losses are 46.5 MVAR. The aggregated wind turbine and solar inverter dynamic capability is +/- 99.03 MVAR. This results in 52.53 MVAR of capability at the POI. An additional +/- 46.7 MVAR of reactive support is required to offset the internal plant losses and meet the APS power factor requirement. The deficiency can be made up by switched capacitor banks.

The worst case scenario for this project is when the solar is at full output and the wind is at full output. Therefore, as shown above, the project needs to add a minimum of 46.7 MVAR of reactive support to meet the APS minimum power factor requirement for all operating conditions. Smaller step sizes will make the caps more useful under a wide range of operating conditions.

3.2 Power Flow and Post-Transient Analysis The power flow and post-transient analysis focuses on high load and generation conditions for summer of 2013. The Pre-Project cases are used as a baseline to measure the impact of the new generation.

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Contingencies are then applied to the cases. A list of contingencies that were simulated is provided in Appendix B. Power flow plots from select contingencies from the Pre-Project and Post-Project cases are included in Appendix A.

Thermal Results 2013 Heavy Summer Conditions Thermal overloads are observed for the N-1 loss of Hassayampa – North Gila 500 kV line on the Barre – Ellis 230 kV line in SCE (100% loading). The addition of Q197 does not exacerbate the loading.

Thermal overloads are observed for the N-1-1 loss of Jojoba – Kyrene & Palo Verde – Rudd 500 kV lines. Simulation of the outage on an APS base case with detailed 69 kV representation in place, yields no thermal overloads for the aforementioned contingency.

2013 Heavy Summer Conditions with Q62 Thermal overloads are observed for the N-1 loss of Hassayampa – North Gila 500 kV line on the Barre – Ellis 230 kV line in SCE (100% loading). The addition of Q197 does not exacerbate the loading.

High East-of-River (9300 MW) Thermal overloads are observed for the N-1 loss of Jojoba – Kyrene 500 kV line on the Gila River 500/230 kV transformer (103% pre-project). Addition of APS Q44 eliminates the overload. With the pre- project overload eliminated the addition of Q197 yields no violations.

High Southern Navajo (2400 MW) Thermal overloads are observed for the N-2 loss of Navajo – Dugas & Yavapai – Westwing 500 kV lines in the post-project base cases. Q197 needs to be tripped offline. Additionally the series capacitors on the Moenkopi – Cedar Mountain (Q196) 500 kV line need to be bypassed to eliminate the overload on the Yavapai – Willow Lake 230 kV line. The Liberty phase shifter overload would be eliminated by the generation re-dispatch required after losing the scheduling rights on Path 51. The mitigation will be detailed in an operating procedure.

Thermal overloads are observed for the N-1 loss of Palo Verde – Colorado River 500 kV and the N-1 loss of Hassayampa – North Gila 500 kV on the IID Coachella Valley 230/92 kV transformer. The addition of Q197 does not exacerbate the loading. Since the start of this study, the standard IID modeling at Coachella reflects three transformers rather than the two that are modeled in these studies. A third transformer eliminates the overloads shown.

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Table 3.1 Thermal loading summary 2013 High Southern Navajo (Path 51) Post-Project Rating Pre-Project Post-Project Monitored Element (Amps-Line/ (w/mitigation) MVA-xfmr) Amps % Amps % Amps % N-2 Yavapai-Westwing & Navajo-Dugas 500 kV lines Yavapai-Willow Lake 230 kV line 890 894 100 1015 114 847 95 Liberty Phase Shifter bypass 1298 1260 97 1335 103 1306 101 N-1 Palo Verde-Colorado River 500 kV line Coachella Valley 230/92 kV xfrm 150 159 107 159 107 N-1 Hassayampa-North Gila 500 kV line Coachella Valley 230/92 kV xfrm 150 169 114 169 114 Case 13 14 14 * Recent modeling change of a third transformer removes the loading problems

Light Loading Results indicate that there are no pre-project or post-project violations.

Voltage Results 2013 Heavy Summer Conditions Multiple voltage violations are observed in the SCE area around Colorado River and Red Bluff for loss of Palo Verde – Colorado River 500 kV line. There are multiple projects added to the Colorado River and Red Bluff substations which had limited voltage support. Addition of the Q197 project reduced and in some cases eliminated the voltage violations therefore no mitigation is required from Q197.

2013 Heavy Summer Conditions with Q62 Multiple voltage violations are observed in the SCE area around Colorado River and Red Bluff for loss of Palo Verde – Colorado River 500 kV line. There are multiple projects added to the Colorado River and Red Bluff substations which had limited voltage support. Addition of the Q197 project reduced and in some cases eliminated the voltage violations therefore no mitigation is required from Q197.

High East-of-River (9300 MW) Multiple voltage violations are observed in the SCE area around Colorado River and Red Bluff for loss of Palo Verde – Colorado River 500 kV line. There are multiple projects added to the Colorado River and Red Bluff substations which had limited voltage support. Addition of the Q197 project reduced and in some cases eliminated the voltage violations therefore no mitigation is required from Q197.

High Southern Navajo (2400 MW) Results indicate that there are no pre-project or post-project violations.

Light Loading Results indicate that there are no pre-project or post-project violations.

WATS voltage violations for all the cases are identified in Appendix E.

3.3 Transient Stability Analysis As referenced in the Reliability Criteria section of this report, the system should meet the following transient stability performance criteria for a NERC/WECC Category ‘B’ disturbance (N-1):

 Transient voltage dip should not be below 25% at any load busses or 30% at any non-load busses at any time.

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 The duration of a transient voltage dip greater than 20% should not exceed 20 cycles at load busses.  The minimum transient frequency should not fall below 59.6 Hz for more than 6 cycles at load busses.

Appendix D contains transient stability plots of selected contingencies that provide a representative illustration of the transmission system’s Post-Project voltage response.

2013 Heavy Summer Conditions Sixty-Two (62) outages were selected for transient stability evaluation. There are no stability violations in the pre- or post-project cases.

High East-of-River (9300 MW) Thirty-Nine (39) outages were selected for transient stability evaluation. There are no stability violations in the pre- or post-project cases.

High Southern Navajo (2400 MW) Thirty-Nine (39) outages were selected for transient stability evaluation. There are no stability violations in the pre- or post-project cases.

Light Loading Sixty-Two (62) outages were selected for transient stability evaluation. There are no stability violations in the pre- or post-project cases.

Navajo Generation + 7% Eleven (11) outages were selected for transient stability evaluation. There are no stability violations in the pre- or post-project cases. However, a unit arming scheme exists for the Navajo plant under various scenarios of facilities being out of service. The addition of generation into the Southern Navajo transmission system may impact that scheme. The IC will be required to be incorporated into the scheme to share unit arming exposure and assure no increased exposure to the existing Navajo plant.

3.4 Short-Circuit / Fault Duty Analysis Short-circuit analysis of the proposed generator was performed by the APS Protection Department, using the CAPE program and parameters supplied by the Applicant. The new generation project was represented as a constant current source. Fault duties were calculated for both single-phase–to-ground and three-phase faults at substations busses in the immediate surrounding area before and after the proposed generator installation. The results presented here assume a “worst-case” scenario.

No equipment short-circuit ratings in the vicinity of the project were exceeded as a result of the projects. Table 3.2 describes the short-circuit results.

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Table 3.2 Short-Circuit Analysis Results - 1.05 Pre-Fault Voltage

Pre-Project including Q62 Post-Project (Q196 & Q197) Min Brkr. Station 3 Ph. Ph-G 3 Ph. Ph-G X/R X/R ΔI X/R ΔI X/R Rating (kA) (kA) (kA) (kA) (kA) Q196 525kV POI N/A N/A N/A N/A 28.8 28.8 9.5 16.8 16.8 14.9 TBD Q197 525kV POI N/A N/A N/A N/A 23.3 23.3 -11.7 21.5 21.5 6.8 TBD Cedar Mtn 525kV 14.2 10.6 5.8 13.6 14.6 0.4 12.0 6.1 0.3 20.5 63 Moenkopi 525kV 29.2 14.3 19.0 13.5 31.8 2.6 14.6 20.2 1.2 13.9 40 Navajo 525kV 34.3 21.9 30.0 22.4 35.1 0.8 21.6 30.4 0.4 22.4 40 Four Corners 23.2 28.1 24.5 21.0 23.3 0.1 28.0 24.5 0.0 21.1 63 525kV Four Corners 39.3 28.3 44.9 21.0 39.4 0.1 28.3 45.0 0.1 21.1 50 345kV Westwing 525kV 39.8 21.2 32.4 24.0 39.9 0.1 21.1 32.4 0.0 24.0 40 Yavapai 525kV 13.2 7.3 8.7 11.2 13.4 0.2 7.9 8.7 0.0 11.8 40 Eldorado 525kV 36.5 12.6 27.1 24.7 37.0 0.5 12.5 27.5 0.4 24.4 63 Mead 525kV 28.2 24.1 21.9 34.5 28.4 0.2 24.0 22.1 0.2 34.4 40 Mead 230kV 52.6 29.8 48.7 36.1 52.7 0.1 29.8 48.8 0.1 36.1 90 (North) Mead 230kV 62.2 25.1 57.1 30.4 62.3 0.1 25.1 57.2 0.1 30.4 90 (South) McCullough 525kV 37.6 18.3 28.1 35.8 38.1 0.5 18.0 28.5 0.4 35.4 50 McCullough 230kV 60.7 25.8 53.0 43.4 60.9 0.2 25.8 53.1 0.1 43.4 63

3.5 Results & Findings Summary The results of the SIS indicate that the addition of Q197 requires an operating procedure to be put in place for situations when Path 51 loading increases above 2,500 MW. In these cases, the N-2 of the Navajo-Dugas and Yavapai-Westwing 500 kV lines would require the Q197 generation be removed from the system and the Moenkopi – Cedar Mountain (Q196) series capacitors would need to be bypassed.

4 Cost & Construction Time Estimates The cost estimates for Q197 are listed below. The estimates do not include any costs for new rights-of- way that may be needed. The estimates are separated into two categories. The first of which is Network Upgrades and the second is Transmission Providers Interconnection Facilities. A high-level, good faith, non-binding cost estimate for this required transmission work is as follows:

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Table 4.1 Network Upgrades Estimated Cost Schedule- Months after LGIA execution Q197 500 kV Switchyard (assumes a 4 breaker $ 9,000,000 21 ring bus, no cost for land and rough grading by others) Facilities to bring service to new 500 kV $ 1,700,000 12 Switchyard for station service Communications $ 3,500,000 21 Overhead 500kV for new Switchyard $ 4,100,000 12 Moenkopi, 500kV line relays $ 200,000 3 Eldorado, 500kV line relays $ 200,000 3 Total $18,700,000 21

Table 4.2 Transmission Provider Interconnection Facilities Estimated Cost Schedule- Months after LGIA execution Termination facilities in new Q197 $1,100,000 12 500kv Switchyard (including A-frames, line disconnect switch, CCVTs, extended range CTs) Total $1,100,000 12

Included in the cost assumptions is a new 500 kV switchyard built as a four breaker ring bus. All the costs for these components are Network Upgrades which are subject to repayment in accord with the APS OATT. Costs for these Network Upgrades are estimated to be $18.7 M. The attached diagram identifies additions that are needed for the new 500 kV switchyard and the generator interconnection.

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Figure 4-1: Q197 Switching Station

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List of Acronyms

ACC Arizona Corporation Commission ACSS Aluminum Conductor Steel Supported ANPP Arizona Nuclear Power Project APS Arizona Public Service ATC Available Transfer Capability CAISO California Independent System Operator Corporation CAWCD Central Arizona Water Conservation District CCVT Coupling Capacitor Voltage Transformer COD Commercial Operation Date CSP Concentrated Solar Power CT Combustion Turbine or Current Transformer EPE El Paso Electric ER Energy Resource ERIS Energy Resource Interconnection Service FaS Facilities Study FERC Federal Energy Regulatory Commission FeS Feasibility Study GT Gas Turbine IC Interconnection Customer IID Imperial Irrigation District IR Interconnection Request LADWP Los Angeles Department of Water and Power LGIA Large Generator Interconnection Agreement NEC Navopache Electric Cooperative NERC North American Electric Reliability Corporation NR Network Resource NRIS Network Resource Interconnection Service NSTS Navajo Southern Transmission System NTUA Navajo Tribal Utility Authority

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OASIS Open Access Same Time Information System OATT Open Access Transmission Tariff PG&E Pacific Gas & Electric PNM Public Service Company of New Mexico POI Point Of Interconnection PPA Purchase Power Agreement PSLF/PSDS/SCSC Positive Sequence Load Flow/Positive Sequence Dynamic Simulation/Short-Circuit Saturation Curve PST Phase-Shifting Transformer PV Photovoltaic RAS Remedial Action Scheme (also known as SPS) RFP Request for Proposal SCE Southern California Edison Company SDG&E San Diego Gas & Electric Company SIS System Impact Study SLG fault Single Line-to-Ground fault SPS Special Protection System (also known as RAS) SRP Salt River Project SSVEC Sulphur Springs Valley Electric Cooperative, Inc. SVC Static VAR Compensator SVD Static VAR Device SWTC Southwest Transmission Cooperative TEP Tucson Electric Power TPIF Transmission Provider’s Interconnection Facilities WAPA Western Area Power Administration WECC Western Electricity Coordinating Council

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