Q85 Generation Interconnection

A subsidiary of Pinnacle West Capital Corporation Q85 Generation Interconnection Interconnection Facilities Study AMENDED APS Contract No. 52386 By Arizona Public Service Company Transmission Planning March 5, 2012

FACILITIES STUDY Q85 PROPOSED GENERATION TABLE OF CONTENTS 1. Introduction... 3 2. Study Results... 4 2.1. Power Flow... 4 2.2. Voltage Flicker... 4 2.3. Transient Analysis... 5 2.4. Post-transient Governor Power Flow Analysis... 5 3. Cost Estimates... 6 3.1. Summary of Cost and Construction Time Estimates... 6 3.2. Network Upgrades... 6 3.3. Transmission Provider s Interconnection Facilities... 7 4. System Reinforcements... 7 5. Power Factor Requirements... 7 LIST OF APPENDICES Appendix A Select Power Flow Plots Appendix B Transient Stability Modeling Appendix C Transient Stability Plots Appendix D Construction Schedule Details Appendix E County Line Substation One-Line Diagram Page 2

1. Introduction APS performed this Generator Interconnection Facilities Study (FaS) in response to a valid generator interconnection request by the Interconnection Customer (IC). The IC is listed in APS s Active Generator Interconnection Queue as Queue Position 85. The purpose of this study is to provide cost and construction schedule estimates for the facilities needed to interconnect the IC s proposed 20 MW photovoltaic solar generation facility (Q85) located near Hyder, Arizona in Yuma County. The Point of Interconnection (POI) requested for the FaS is the APS County Line 69 kv switchyard. As of the date of this FaS, the County Line switchyard is energized and in-service. The proposed Commercial Operation Date for Q85 is December 31, 2011 with generator testing beginning October 1, 2011 (see Section 3.1 for further details). This IC has already completed a System Impact Study (SIS). The Interconnection Customer has chosen to interconnect as an Energy Resource Interconnection Service (Energy Resource). Delivery of the Q85 output beyond the POI would be on an as-available basis only. The delivery of the Q85 output would be subject to the firm or non-firm transmission capacity that may be available when a transmission service request is made. Nothing in this report constitutes an offer of transmission service or confers upon the Interconnection Customer, any right to receive transmission service. APS may not have the Available Transfer Capability (ATC) to support the Transmission Service for the interconnection described in this report. Figure 1 below shows a general depiction of the 69 kv system around Q85 s proposed POI. Figure 1. Project Location and 69 kv System Page 3

2. Study Results 2.1. Power Flow Power flow analysis was performed on all 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. These Pre-Project and Post-Project cases were evaluated for Category A (N-0 or all lines in service) conditions. Then approximately 60 Category B and 2 Category C contingencies were applied to the cases. Areas 14 (Arizona) and 73 (WAPA R.M.) were monitored. Voltage results focused on buses at 69 kv and above, as well as all Project buses. Select power flow plots are included in Appendix A. Since the System Impact Study (SIS) was completed for Q85, there are three planned changes that affect the flows near the Project's interconnection: 1) Q31 has delayed its In-Service Date from 2011 to 2013, 2) a 12 kv generator will interconnect to the County Line Substation prior to this Project, and 3) two 12 kv generators will interconnect to the Cotton Center Substation prior to this Project. These planned changes have been modeled and were used in the analysis. The results of the 2011, 2013 and 2014 power flow analyses indicate the Project triggered one new overload in the monitored systems of Arizona and WAPA R.M are shown below. The results are shown below. 1 Table 2.1: 2011 N-1 Overloads Emergency Monitored Branch Contingency Description Rating (Amps) BUNYAN - CNTYLINE 69 kv % Emergency Rating Pre Post 2011 2011 N-1 SADDLEMT-CNTYLINE 69 kv 301.2 50.4 106.1 In 2011, the Project triggers one new overload: Bunyan-County Line 69 kv. This overload did not show up in the SIS and is triggered by Q85 in the FaS following the addition of the 12 kv County Line generation. Q85 will not be responsible for the costs associated with upgrading the Bunyan- County Line 69 kv line. Voltage N-0 The power flow results showed no Project caused N-0 voltage violations. Voltage N-1 and N-2 The power flow results showed no Project caused N-1 or N-2 voltage violations. 2.2. Voltage Flicker The results found no Project caused voltage flicker deviations greater than 1.5%. 1 Though not Project-related, in 2014 the Palo Verde-Delany 500 kv outage causes the case solution to diverge without the applicable SPS, opening the Hassayampa Tap-Hassayampa Pump 230 kv line and/or tripping nearby generation. Detailed discussion is not part of this report. Page 4

Table 2.3: 2011 Voltage Flicker 100% Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus Volt (pu) Volt (pu) Deviation (%) Volt (pu) Deviation (%) Volt (pu) Deviation (%) Volt (pu) Deviation (%) Q085 69.00kV 1.031 1.0214-0.93% 1.0246-0.62% 1.0282-0.27% 1.0305-0.05% CNTYLINE 69.00kV 1.024 1.0204-0.35% 1.0222-0.18% 1.0238-0.02% 1.0241 0.02% AZTEC 69.00kV 1.0358 1.0323-0.35% 1.034-0.17% 1.0356-0.02% 1.036 0.02% HORN 69.00kV 1.0242 1.0206-0.35% 1.0223-0.18% 1.0239-0.02% 1.0243 0.02% SADDLEMT 69.00kV 0.9999 1.0028 0.29% 1.0029 0.30% 1.0023 0.24% 1.0007 0.08% BUNYAN 69.00kV 1.0179 1.0248 0.68% 1.024 0.60% 1.022 0.39% 1.0191 0.12% PALOMA 69.00kV 1.0227 1.0271 0.44% 1.0265 0.37% 1.0252 0.24% 1.0234 0.07% GILABEND 69.00kV 1.0282 1.0315 0.32% 1.031 0.27% 1.0299 0.18% 1.0287 0.05% BUCKEYE 69.00kV 1.0352 1.0366 0.14% 1.0363 0.12% 1.0359 0.07% 1.0354 0.02% 2.3. Transient Analysis The results of the 2011 transient stability analysis indicate the Project did not trigger any transient stability violations. See Appendix B for the Transient Stability Modeling and Appendix C for select Transient Stability Plots. 2.4. Post-transient Governor Power Flow Analysis The results of the 2011 post-transient governor power flow analysis indicate the Project did not trigger any voltage deviation violations. Page 5

3. Cost Estimates 3.1. Summary of Cost and Construction Time Estimates The cost estimates for the various parts of the Q85 Interconnection Project are listed in more detail in sections 3.2 and 3.3 below. Table 3.1 below provides a summary of which costs are considered Network Upgrades and which are Transmission Provider s Interconnection Facilities. Table 3.1: Q85 Project Cost Summary Network Upgrades Transmission Provider's Interconnection Facilities County Line 69kV Ring Bus $260,000 $162,000 Communications $70,000 Subtotal $260,000 $232,000 Grand Total $492,000 Table 3.2 below provides a summary of the construction schedules. Additional schedule details can be found in Appendix D. Table 3.2: Construction Time Estimates Facility Schedule County Line 69kV Ring Bus (TPIF) 9 Months Communications 8 Months Total 9 Months The summary provided in Table 3.2 above shows a total estimated completion time of 9 months. Therefore, the originally requested In-Service Date of October 31, 2011 cannot be met. Under the current APS SGIP/SGIA extension policy, the Interconnection Customer will be offered a new projected In-Service Date equal to the soonest date that is practical as determined by APS, plus an additional up to six (6) month extension if the Interconnection Customer requests such extension. Please note that the Commercial Operation Date must be within the ten (10) year transmission planning period from the date of the valid Interconnection Request. 3.2. Network Upgrades APS has recently built the County Line switchyard to improve the operation and reliability of our 69 kv transmission system. There is also new generation at County Line that is interconnected at 12 kv which will required APS to install a 69/12 kv transformer at the 69 kv switchyard. The new layout of County Line can be seen in the one-line in Appendix E (Network Upgrades shown in green). One exception is that there are no plans at this time to install a second 69/12 kv transformer, since there are no plans to have any APS load at County Line at this time. Due to the change in plans, Q85 will not be responsible for expanding the existing Hyder substation. Instead, the Network Upgrades for the Q85 project will consist of expanding the 69 kv ring bus at Page 6

County Line for an additional breaker and line position. The County Line switchyard was energized in the Fall of 2011. The addition of the new County Line switchyard will still cause the normally open Hyder (now County Line)-Saddle Mountain 69 kv line to become normally closed. APS will also be responsible for rebuilding the Saddle Mountain 69 kv tap to double-circuit 795 ACSS conductor. This rebuild will bring both the Bunyan and Saddle Mountain 69 kv lines into the new County Line switchyard. Q85 will not be responsible for rebuilding the Bunyan-County Line 69 kv line. All of the costs associated with the above mentioned work are considered Network Upgrades, which are typically repaid to the Interconnection Customer, per FERC rules, as transmission credits over a maximum of twenty (20) years. The assumptions used for all cost estimates are as follows: The County Line switchyard is in-service Rebuilds are assumed that lines will be rebuilt in existing location APS will construct, own and operate the facilities in the County Line switchyard and the portion of 69 kv line from the County Line 69 kv bus up to the first structure outside the switchyard fence The IC will construct, own and maintain the 69 kv generation tie-line from the first structure outside the switchyard fence to the Q85 site The IC will be responsible for providing a fiber optic communications path from the Q85 facility to the County Line switchyard All estimates are in 2011 dollars 3.3. Transmission Provider s Interconnection Facilities The Transmission Provider s Interconnection Facilities (TPIF) required for the Q85 project include the necessary switches, bus work, etc needed to bring the Q85 69 kv generation tie-line into the County Line switchyard. These facilities are shown in red in Appendix E. The communication costs are also considered TPIF, which includes all necessary equipment as well as any work to terminate the IC s fiber line from the Q85 site to the County Line switchyard. These costs are the sole responsibility of the Interconnection Customer, and will not be reimbursed. 4. System Reinforcements The Interconnection Customer has chosen to interconnect as an Energy Resource, with delivery of the Q85 output beyond the POI on an as-available transmission basis only, using firm and non-firm transmission capacity that may be available when a transmission service request is made. 5. 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 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. Page 7

Appendix A Select Power Flow Plots Plot Listing: Page 8

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Appendix B Q85 Transient Stability Modeling Page 14

Plant Dynamic Model Data utilizing Emerson PV Inverters Input Parameters: Emerson Inverters Q085 Constant Description From IC rsrc Generator source resistance, pu on plant base 0.00 xsrc Generator source reactance, pu on plant base 0.00 Vratio Ratio of PV array open circuit to peak power voltage 1.25 Iratio Ratio of PV array short circuit to peak power current 1.05 Tdc Inverter DC capacitor bank time constant, sec 0.008 Itlim Inverter AC thermal current limit, pu on plant base 1.00 Ixlim Inverter AC transient active current limit, pu on plant base 1.45 Iylim Inverter AC transient reactive current limit, pu on plant base 1.00 Kpdc DC voltage regulator proportional gain 7.65 Kidc DC voltage regulator integral gain 0.29 Kpac AC voltage regulator proportional gain 1 Kiac AC voltage regulator integral gain 0.5 QMOD Reactive power mode (0 = constant reactive current, 1 = constant reactive power, 2 = constant power factor, 3 = voltage regulation) TQT Reactive power transducer time constant, sec 0.2 TQR Reactive power regulator time constant, sec 0.4 TSC AC voltage regulator communications delay, sec 1 OV1L Overvoltage trip point #1, pu 1.36 OV1T Overvoltage delay #1, sec 0.016 OV2L Overvoltage trip point #2, pu 1.20 OV2T Overvoltage delay #2, sec 0.16 OV3L Overvoltage trip point #3, pu 1.10 OV3T Overvoltage delay #3, sec 1.00 UV1L Undervoltage trip point #1, pu 0.50 UVIT Undervoltage delay #l, sec 0.16 UV2L Undervoltage trip point #2, pu 0.88 UV2T Undervoltage delay #2, sec 2.00 OFL Overfrequency trip point, pu 60.5 OFT Overfrequencv delay, sec 1.00 UF1L Underfrequency trip point #1, pu 57.0 UF1T Underfrequency delay #1, sec 0.16 UF2L Underfrequency trip point #2, pu 59.8 UF2T Underfrequency delay #2, sec 300.0 0 Page 15

Appendix C Q85 Transient Stability Plots Page 16

Transient Stability Analysis was run on each of the contingencies listed in the table below. This appendix includes a sampling of the plots that were created, which are highlighted in grey. Plots for the remaining contingencies may be obtained on request. Contingency #76 intentionally trips the Project generation. Contingency # Pre Post!N-0_FLAT_RUN Flat sw03-500-has-jjb-slo 3 sw04-500-has-ngi-slo 4 sw05-500-has-pnw-slo 5 sw06-500-jjb-kyr-slo 6 sw07-500-kyr-brn-slo 7 sw08-500-pvd-rud-slo-ts 8 sw09-500-pvd-wwg-1-slo-ts 9 sw10-500-pvd-wwg-2-slo-ts 10 sw12-500-jjb-gil_1 12 sw13-500-jjb-gil-2 13 sw14-230-gbd-pan-5c-slo 14 sw16-230-rud-pvl_5c_slo 16 sw17-230-buk-lib-wsps-5c-slo 17 sw19-rud_500_230_1 19 sw20-rud_500_230_2 20 sw21-rud_500_230_3 21 sw22-rud_500_230_4 22 sw23-gil_500_230_1 23 sw24-kyr_500_230_6 24 sw25-kyr_500_230_7 25 sw27-glb_230_069_1 27 sw28-glb_230_069_2 28 sw30-buk_230_069_1 30 sw31-buk_230_069_2 31 sw32-69-gil-thay-slo 32 sw33-69-thay-why-slo 33 sw34-69-gil-cotn-slo 34a sw34-69-cotn-gillespi-slo 34b sw35-69-gillespi-buck-slo 35 sw36-69-pvngpump-baseline-slo 36 sw37-69-buckeye-watsonw-slo 37 sw39-69-gillwest-pvngpump-slo 39 sw40-69-pvngpump-winter-slo 40 sw41-69-saddlemt-buckeye-slo 41 sw43-69-gil-bun-slo 42 sw44a-69-bunyan-cntyline-slo 43 sw45a-69-cntyline-horn-slo 44 sw46a-69-cntyline-saddlemt-slo 46 sw63-500-has-jjb-pnw-dlo 63 sw64-gil-jjb_500_1-2_wsps 64 Gen trip at Detroit-stable sw74-69-aztec-q084-slo 74 sw76-69-cntyline-q085-slo 76 Page 17

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Appendix D Construction Schedule Details Page 38

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Appendix E County Line Substation One-Line Diagram Page 40

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