A subsidiary of Pinnacle West Capital Corporation Q197 Generator Interconnection Project System Impact Study APS Contract No. 52453 By 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 Page 2 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. Page 3 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 Page 4 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