Q217 Generator Interconnection Project

Transcription

1 Q217 Generator Interconnection System Impact Study APS Contract No By Arizona Public Service Company Transmission Planning November 25, 2013 Version 2.0 Prepared by Utility System Efficiencies, Inc.

2 Q217 SYSTEM IMPACT STUDY TABLE OF CONTENTS EXECUTIVE SUMMARY Study Description and Assumptions Post Case Modeling Dynamic Data Reliability Criteria Power Factor Criteria (Steady State) Power Flow Criteria Transient Stability Criteria Study Methodology Power Factor Requirements Power Flow Post-Transient Transient Stability Results and Findings Reactive Support Power Flow and Post-Transient Analysis Flicker Analysis Transient Stability Analysis Short Circuit / Fault Duty Analysis Results & Findings Summary Cost & Construction Time Estimates Appendix A Power Flow Diagrams Appendix B List of Contingencies Appendix C Transient Stability Data Appendix D Transient Stability Plots LIST OF APPENDICES Page 1

3 EXECUTIVE SUMMARY This section summarizes the System Impact Study (SIS) results for a proposed photovoltaic generation interconnection of 35 MW in the Arizona Public Service (APS) transmission system. Additional 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 Desert Sands 69 kv switchyard. 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 #217. The Applicant has proposed to add solar photo-voltaic generation with a maximum net output of 35 MW, connecting directly to the Desert Sands 69 kv switchyard in the second quarter of A Network & Energy Resource interconnection evaluation was requested. Figure E.1 illustrates this proposed interconnection and the nearby transmission facilities. This SIS used the machine parameters and characteristics provided by the Applicant. Studies consisted of computer-based power flow, post-transient, transient stability, voltage flicker, and short-circuit/fault duty analyses. This study modeled the proposed generation interconnection under anticipated 2014 summer peak conditions. Select contingencies which stressed the transmission system were simulated. Power flow, transient stability, and post-transient results were monitored for APS, WAPA, and other neighboring systems. Flicker was monitored for the buses in the immediate project area. 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 Point of Interconnection (POI), subject to system conditions. The APS OATT also requires Interconnection Customers to be able to achieve +/ 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 +/ power factor, as long as the is online and generating. If the s equipment is not capable of this type of response, a dynamic reactive device will be required. APS has the right to disconnect the 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 Q217 results in no post-project reliability violations. However, the project as designed is not able to meet the power factor requirements at this time. An additional 5.5 Mvar reactive support is necessary to compensate for losses from the generator terminals to the POI. Page 2

4 Table 1.1 Summary of Interconnection Cost and Lead Times Facility Costs ($000) Timeline (months) Network Upgrades Q217 Trans. Provider s Interconnection Facilities Grand Total The total estimated completion time for interconnecting the Q217 project is months. The long lead time component for this project is getting Right Of Way from the State of Arizona that will be required for the rebuild of up to two miles of an existing APS 69kv line and the routing of the generator interconnection tie line as it gets set to enter the switchyard. Since the requested interconnection date can t be met, APS and the Interconnection Customer must discuss and mutually agree to a new and acceptable projected In-Service Date. The customer requested a Network Resource interconnection and as such an evaluation was made and conclusions are that in the 2014 timeframe, APS would be able to accommodate this project as a Network Resource. However, this evaluation result is only good for the time in which it was performed. APS could sell transmission service over the local facilities at any time which could then result in insufficient transmission to accommodate this project as a Network Resource. Figure E-1. Q217 and Nearby Transmission Facilities Page 3

5 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, voltage flicker, transient stability and post-transient study work was completed using General Electric s Positive Sequence Load Flow (GE-PSLF), version 18.0_01. The study used the 2014 Heavy Summer APS detailed planning case sm14#16.sav. This case has undergone review and updates by all of the Arizona utilities for planning purposes. Pre- and post-project base cases were developed. The new generation was offset with the Palo Verde (PV) generation group. Sensitivities were run for the following scenarios. Pre- and Post-project cases were developed for each scenario. 1) Max Yuma Load/Generation pattern 2) 2016 Yuma configuration 3) 2016 Yuma configuration with max Yuma Load/Generation pattern 4) 2016 Yuma configuration with max Yuma Load/Generation pattern and TS8 project 5) 2016 Yuma configuration with max Yuma Load/Generation pattern, TS8 project, and Q43 with max output. 1.1 Post Case Modeling Requestor Q217 was represented in the power flow model as a single 35 MW unit connected to a 0.27 kv bus. A transformer steps the voltage up from 0.27kV to 34.5kV. Another transformer steps the voltage up from 34.5kV to 69kV. The project was connected via a 1.5 mile 69kV line to Desert Sands 69kV switchyard. Figure 1-1 represents the Q217 power flow model. Desert Sands 69 kv 1.5 miles 69 kv R= X= kv R= X= MW +/ MVAR Figure 1-1: Q217 Power Flow Model Power scheduled to Palo Verde Page 4

6 Mesquite generation was reduced to offset the interconnection 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. Major Branch Flows Table Case Attributes Pre- Post- Pre- HYL Post- HYL Pre config Post config N.Gila-Gila 69kV Gila-AR FH TP 69kV N.Gila-Mittry 69kV Sanguine-Mittry 69kV Redondo-Sanguine 69kV Foothill Tap-Redondo 69kV Foothill Tap-Foothill 69kV Pacific-N.Gila 69kV Quechan-Pacific 69kV th St-Quechan 69kV Sanguine-SW7 69kV SW7-Ivalon 69kV Araby-AR FH TP 69kV MAB-Araby 69kV S.Oneill-MAB 69kV Waldrip-S.Oneill 69kV Waldrip-Baja 69kV San Luis-Baja 69kV Laguna-San Luis 69kV Yuca W-Laguna 69kV Yuca W-Dupont 69kV Dupont-32nd St 69kV th St-32nd St 69kV Cocopah-32nd St 69kV th St-Cocopah 69kV Riverside-10th St 69kV Riverside-Cocopah 69kV Yucca E-Riverside 69kV Hoodoo Wash-N.Gila 500kV 1,387 1,366 1,054 1,041 1,388 1,367 N.Gila-Imperial Valley 500kV 1,192 1, ,191 1,191 Pilot Knob-Yucca 161kV Gila-Araby TP-W 69kV Araby TP-E-Redondo 69kV Foothills-Araby S 69kV Araby N-Araby TP-W 69kV Araby N-Araby TP-E 69kV Control Area Information AZ Load 19,550 19,550 19,724 19,724 19,550 19,550 AZ Lossess AZ Generation 26,559 26,558 25,934 25,933 26,559 26,558 AZ Exports 6,308 6,308 5,508 5,508 6,308 6,308 Case Page 5

7 Major Branch Flows Pre config/ HYL Post config/ HYL Pre config/ HYL/TS8 Post config/ HYL/TS8 Pre config/ HYL/TS8/Q43 max Post config/ HYL/TS8/Q43 max N.Gila-Gila 69kV Gila-AR FH TP 69kV N.Gila-Mittry 69kV Sanguine-Mittry 69kV Redondo-Sanguine 69kV Foothill Tap-Redondo 69kV Foothill Tap-Foothill 69kV Pacific-N.Gila 69kV Quechan-Pacific 69kV th St-Quechan 69kV Sanguine-SW7 69kV SW7-Ivalon 69kV Araby-AR FH TP 69kV MAB-Araby 69kV S.Oneill-MAB 69kV Waldrip-S.Oneill 69kV Waldrip-Baja 69kV San Luis-Baja 69kV Laguna-San Luis 69kV Yuca W-Laguna 69kV Yuca W-Dupont 69kV Dupont-32nd St 69kV th St-32nd St 69kV Cocopah-32nd St 69kV th St-Cocopah 69kV Riverside-10th St 69kV Riverside-Cocopah 69kV Yucca E-Riverside 69kV Hoodoo Wash-N.Gila 500kV 1,055 1, N.Gila-Imperial Valley 500kV Pilot Knob-Yucca 161kV Gila-Araby TP-W 69kV Araby TP-E-Redondo 69kV Foothills-Araby S 69kV Araby N-Araby TP-W 69kV Araby N-Araby TP-E 69kV Control Area Information AZ Load 19,724 19,724 19,724 19,724 19,749 19,749 AZ Lossess AZ Generation 25,934 25,933 25,932 25,930 26,172 26,171 AZ Exports 5,508 5,508 5,508 5,508 5,718 5,718 Case Page 6

8 1.2 Dynamic Data Appendix C provides the transient stability model used in this study, and the details of these assumptions. Modeling for the new generation utilized machine characteristics provided by the Applicant. Dynamic data file sm14_v2.dyd (developed by APS) was obtained from APS Transmission Planning. A stability plot of the flat run simulation is also provided in Appendix D. 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 (where appropriate) Power Factor Criteria The study applies APS power factor criteria states that a generator must be capable of providing dynamic reactive support within the range of +/-0.95 power factor at the POI (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 postcontingency performance does not result in cascading outages. Established loading limits and voltage performance for other neighboring utilities will be monitored. deviations at any bus must be no more than 5% for N-1 contingencies and no more than 10% for N 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. Page 7

9 Table 1.3 WECC Disturbance-Performance Table of Allowable Effects on Other Systems NERC and WECC Categories A System normal B One element out-of-service C Two or more elements out-of-service D Extreme multipleelement outages Outage Frequency Associated with the Performance Category (outage/year) Not Applicable Transient Dip Standard Not to exceed 25% at load buses or 30% at non-load buses. Not to exceed 20% for more than 20 cycles at load buses. Not to exceed 30% at any bus. Not to exceed 20% for more than 40 cycles at load buses. Minimum Transient Frequency Standard Nothing in addition to NERC Not below 59.6Hz for 6 cycles or more at a load bus. Not below 59.0Hz for 6 cycles or more at a load bus. < Nothing in addition to NERC Post Transient Deviation Standard Not to exceed 5% at any bus. Not to exceed 10% at any bus. Figure 1-2. NERC/WECC Performance Parameters Page 8

10 2 Study Methodology This section summarizes the methods used to derive the power flow, post transient, transient stability and voltage flicker results. Appendix B details the contingencies simulated 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 +/ 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 +/ power factor, as long as the is online and generating. If the s equipment is not capable of this type of response, a dynamic reactive device will be required. APS has the right to disconnect the 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 18.0_01 of General Electric s PSLF/PSDS/SCSC software. Power flow results are monitored and reported for APS and other neighboring systems, including WAPA. Traditional power flow analysis is used to evaluate the thermal and voltage performance of the system under Category A (TPL-001, all elements in service) and Category B (TPL-002, N-1, single contingency) 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 single 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 postcontingency performance does not result in cascading outages. Thermal loading is reported when a modeled transmission element is loaded over 98% of its appropriate MVA rating modeled in the power flow database. Page 9

11 Transmission voltage violations for Category A (TPL-001, no contingency) conditions are reported where per unit voltages are less than 0.95 or greater than For Category B outages (TPL-002, N-1) the voltage violations were reported when the post-contingency voltage deviation was greater than 5%. 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) and Category C (TPL-002, N-2) 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. 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 is run to ensure true power system behavior is 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 are simulated out to 11 seconds to ensure a damped system performance. All simulated faults are 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 Level Breaker clearing times 69 kv 7-cycles 115/161 kv 6-cycles 230 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. Page 10

12 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 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 overfrequency or under-frequency, which can occur due to an area s imbalance between load and generation. Other plotted Parameters Generator Terminal Generator Rotor Speed 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, transient stability, and voltage flicker. 3.1 Reactive Support The project satisfies the minimum power factor requirement. The project online at 35 MW requires a minimum of +/-11.5 MVAR capability at the POI to meet the +/-0.95 power factor requirement. The calculated plant losses are 6.0 MVAR. The aggregated inverter dynamic capability is +/ MVAR. The resultant capability at the POI is 5.99 MVAR. An additional 5.5 Mvar reactive support is required to meet the APS power factor requirement. A static capacitor bank can be added to compensate for the reactive losses. 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 The Pre- cases are used as a baseline to measure the impact of the new generation. Contingencies are then applied to the cases. A list of contingencies that were simulated is provided in Appendix B. Power flow plots from the Pre- and Post- cases are included in Appendix A. Thermal Results 2014 Heavy Summer Case Results indicate that there are 2 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Page 11

13 Table 3.1 Thermal Results Monitored Element Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % N-1 Yucca E-Yucca C 69 kv Riverside-Yucca E 69 kv A A A N-1 Gila-Sonora 69 kv San Luis 69/34.5 kv Bank 20 MVA 23.4 MVA MVA Case 1 2 Page 12

14 2014 Heavy Summer Case w/high Yuma Load/Gen Results indicate that there are 8 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Table 3.2 Thermal Results w/high Yuma Generation Monitored Element N-1 Yucca E-Yucca C 69 kv Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % Riverside-Yucca E 69 kv A A A N-1 Foothill-Desert Sands 69 kv Foothill Tap-Redondo 69kV A A A N-1 Waldrip-South O'Neill 69 kv San Luis 69/34.5 kv Bank 20 MVA 20 MVA MVA N-1 North Gila-Gila 69 kv San Luis 69/34.5 kv Bank 20 MVA 21.6 MVA MVA N-1 North Gila 500/69 kv 1 or 2 San Luis 69/34.5 kv Bank 20 MVA 20.1 MVA MVA N-1 Gila-Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.4 MVA MVA N-1 Knob-Pilot Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.6 MVA MVA N-1 Gila-Sonora 69 kv San Luis 69/34.5 kv Bank 20 MVA 29.3 MVA MVA Case Heavy Summer Case w//2016 configuration Results indicate that there is 1 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Table 3.3 Thermal Results w/2016 configuration Monitored Element N-1 Gila-Sonora 69 kv Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % San Luis 69/34.5 kv Bank 20 MVA 23.4 MVA MVA Case 5 6 Page 13

15 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen Results indicate that there are 8 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Table 3.4 Thermal Results w/2016 configuration, High Yuma Generation Monitored Element N-1 North Gila-Gila 69 kv Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % San Luis 69/34.5 kv Bank 20 MVA 20.3 MVA MVA N-1 Gila-Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.1 MVA MVA 99.5 N-1 Knob-Pilot Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.2 MVA MVA N-1 Gila-Sonora 69 kv San Luis 69/34.5 kv Bank 20 MVA 29.3 MVA MVA Case Heavy Summer Case w//2016 configuration, High Yuma Load/Gen, TS8 project Results indicate that there are 8 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Table 3.5 Thermal Results w/2016 configuration, High Yuma Generation, TS8 project Monitored Element N-1 Tenth St-Quechan 69 kv Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 North Gila-Gila 69 kv San Luis 69/34.5 kv Bank 20 MVA 20.8 MVA MVA N-1 Araby Bus Tie San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 North Gila 500/69 kv 1 or 2 San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 Gila-Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.6 MVA MVA N-1 Knob-Pilot Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 21.0 MVA MVA N-1 Pilot Knob-Yucca 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.4 MVA MVA N-1 Gila-Sonora 69 kv San Luis 69/34.5 kv Bank 20 MVA 29.2 MVA MVA Case 9 10 Page 14

16 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen, TS8 project, Q43 full output Results indicate that there are 8 pre-project violations for this scenario. APS is aware of these and has mitigation plans to reduce the flow. The addition of the Q217 project does not exacerbate the violation. Table 3.6 Thermal Results w/2016 configuration, High Yuma Generation, TS8 project, Q43 full output Monitored Element Rating (AMPS/MVA) Pre- Post- Amps/MVA % Amps/MVA % N-1 Tenth St-Quechan 69 kv San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 North Gila-Gila 69 kv San Luis 69/34.5 kv Bank 20 MVA 20.8 MVA MVA N-1 Araby Bus Tie San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 Gila-Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.6 MVA MVA N-1 Knob-Pilot Knob 161 kv San Luis 69/34.5 kv Bank 20 MVA 21.0 MVA MVA N-1 Pilot Knob-Yucca 161 kv San Luis 69/34.5 kv Bank 20 MVA 20.5 MVA MVA N-1 Gila-Sonora 69 kv San Luis 69/34.5 kv Bank 20 MVA 29.2 MVA MVA Case Page 15

17 Results 2014 Heavy Summer Case Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.7 Results Pre- Post- Monitored Element % change % change N-1 Laguna-San Luis 69 kv line BAJA % 7.00% BOSE % 7.90% SANLUIS % 8.20% SANLUS % 8.50% MEX TAP % 7.90% WF_EQLD % 6.40% SANLUIS % 8.20% WF_EQLD % 8.00% SNL-WALC % 8.20% BAJA % 7.20% SANLUS % 8.90% CFE TIE % 8.20% N-1 Yucca-Laguna 69 kv line BOSE % 5.80% SANLUIS % 6.00% SANLUS % 5.40% MEX TAP % 5.80% SANLUIS % 5.20% WF_EQLD % 5.90% SNL-WALC % 6.00% LAGUNA % 7.10% LAGUNA % 7.10% LAGUNA % 6.90% SANLUS % 5.70% CFE TIE % 6.00% N-1 Mex Tap-Bose 34.5 kv line MEX TAP % <5% N-1 Gila-Sonora 69 kv line SONORA % 5.70% SNLWALCX % 5.50% Case 1 2 Page 16

18 2014 Heavy Summer Case w/high Yuma Load/Gen Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.8 Thermal Results w/high Yuma Generation Pre- % Monitored Element change N-1 Laguna-San Luis 69 kv line Post- % change BAJA % 8.60% BOSE % 10.40% SANLUIS % 10.60% SNLWALCX % <5% SANLUS % 10.70% MEX TAP % 10.40% WF_EQLD % 8.40% SANLUIS % 10.00% WF_EQLD % 10.50% SNL-WALC % 10.60% BAJA % 9.10% SANLUS % 10.90% CFE TIE % 10.60% N-1 Yucca-Laguna 69 kv line SONORA % 5.80% BAJA % 12.00% BOSE % 15.10% SANLUIS % 15.30% SNLWALCX % 7.60% SANLUS % 14.80% MEX TAP % 15.10% WF_EQLD % 12.60% SANLUIS % 13.80% WF_EQLD % 15.20% SNL-WALC % 15.30% LAGUNA % 18.20% BAJA % 12.70% LAGUNA % 18.40% LAGUNA % 17.10% SANLUS % 15.00% CFE TIE % 15.30% N-1 Mex Tap-Bose 34.5 kv line SANLUIS % -6.10% MEX TAP % -8.00% WF_EQLD % -6.40% WF_EQLD % -7.00% SNL-WALC % -6.10% CFE TIE % -6.10% N-1 Gila-Sonora 69 kv line SONORA % 9.10% SNLWALCX % 8.50% WF_EQLD % 5.10% Case 3 4 Page 17

19 2014 Heavy Summer Case w//2016 configuration Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.9 Results w/2016 configuration Pre- % Monitored Element change N-1 Laguna-San Luis 69 kv line Post- % change BAJA % 7.00% BOSE % 7.90% SANLUIS % 8.20% SANLUS % 8.60% MEX TAP % 7.90% WF_EQLD % 6.40% SANLUIS % 8.20% WF_EQLD % 8.00% SNL-WALC % 8.20% BAJA % 7.20% SANLUS % 8.90% CFE TIE % 8.20% N-1 Yucca-Laguna 69 kv line BOSE % 5.90% SANLUIS % 6.10% SANLUS % 5.50% MEX TAP % 5.90% SANLUIS % 5.30% WF_EQLD % 6.00% SNL-WALC % 6.10% LAGUNA % 7.20% LAGUNA % 7.20% LAGUNA % 7.00% SANLUS % 5.70% CFE TIE % 6.10% N-1 Mex Tap-Bose 34.5 kv line MEX TAP % <5% N-1 Gila-Sonora 69 kv line SONORA % 5.50% SNLWALCX % 5.30% Case 5 6 Page 18

20 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.10 Volatge Results w/2016 configuration, High Yuma Generation Pre- % Monitored Element change N-1 Laguna-San Luis 69 kv line Post- % change BAJA % 8.50% BOSE % 10.30% SANLUIS % 10.50% SANLUS % 10.60% MEX TAP % 10.30% WF_EQLD % 8.30% SANLUIS % 10.00% WF_EQLD % 10.40% SNL-WALC % 10.50% BAJA % 9.00% SANLUS % 10.80% CFE TIE % 10.50% N-1 Yucca-Laguna 69 kv line SONORA % 5.50% BAJA % 11.80% BOSE % 14.90% SANLUIS % 15.10% SNLWALCX % 7.30% SANLUS % 14.50% MEX TAP % 14.90% WF_EQLD % 12.40% SANLUIS % 13.60% WF_EQLD % 15.00% SNL-WALC % 15.10% LAGUNA % 18.00% BAJA % 12.50% LAGUNA % 18.10% LAGUNA % 16.80% SANLUS % 14.80% CFE TIE % 15.10% N-1 Mex Tap-Bose 34.5 kv line SANLUIS % -6.10% MEX TAP % -8.00% WF_EQLD % -6.40% WF_EQLD % -7.00% SNL-WALC % -6.10% CFE TIE % -6.10% N-1 Gila-Sonora 69 kv line SONORA % 9.10% SNLWALCX % 8.50% WF_EQLD % 5.00% Case 7 8 Page 19

21 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen, TS8 project Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.11 Results w/2016 configuration, High Yuma Generation, TS8 project Pre- % Monitored Element change N-1 Laguna-San Luis 69 kv line Post- % change BAJA % 6.20% BOSE % 7.30% SANLUIS % 7.50% SANLUS % 7.90% MEX TAP % 7.30% WF_EQLD % 5.90% SANLUIS % 7.40% WF_EQLD % 7.40% SNL-WALC % 7.50% BAJA % 6.50% SANLUS % 8.00% CFE TIE % 7.50% N-1 Yucca-Laguna 69 kv line BAJA % 6.90% BOSE % 8.80% SANLUIS % 9.00% SANLUS % 8.60% MEX TAP % 8.80% WF_EQLD % 7.20% SANLUIS % 8.10% WF_EQLD % 8.90% SNL-WALC % 9.00% LAGUNA % 11.20% BAJA % 7.30% LAGUNA % 11.30% LAGUNA % 10.60% SANLUS % 8.80% CFE TIE % 9.00% N-1 Mex Tap-Bose 34.5 kv line SANLUIS % -5.70% MEX TAP % -7.60% WF_EQLD % -6.00% WF_EQLD % -6.60% SNL-WALC % -5.70% CFE TIE % -5.70% N-1 Gila-Sonora 69 kv line SONORA % 8.40% SNLWALCX % 7.90% Case 9 10 Page 20

22 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen, TS8 project, Q43 full output Results indicate that there are both pre-project and post-project voltage violations for multiple contingencies in the Yuma area. This is a known problem to APS planning and mitigation is being assessed. The addition of the Q217 project does not exacerbate the violations. Table 3.12 Results w/2016 configuration, High Yuma Generation, TS8 project, Q43 full output Pre- % Monitored Element change N-1 Laguna-San Luis 69 kv line Post- % change BAJA % 6.20% BOSE % 7.40% SANLUIS % 7.60% SANLUS % 7.90% MEX TAP % 7.40% WF_EQLD % 5.90% SANLUIS % 7.40% WF_EQLD % 7.50% SNL-WALC % 7.60% BAJA % 6.50% SANLUS % 8.10% CFE TIE % 7.60% N-1 Yucca-Laguna 69 kv line BAJA % 7.00% BOSE % 8.90% SANLUIS % 9.10% SANLUS % 8.70% MEX TAP % 8.90% WF_EQLD % 7.20% SANLUIS % 8.20% WF_EQLD % 9.00% SNL-WALC % 9.10% LAGUNA % 11.40% BAJA % 7.40% LAGUNA % 11.40% LAGUNA % 10.70% SANLUS % 8.90% CFE TIE % 9.10% N-1 Mex Tap-Bose 34.5 kv line SANLUIS % -5.70% MEX TAP % -7.60% WF_EQLD % -6.00% WF_EQLD % -6.60% SNL-WALC % -5.70% CFE TIE % -5.70% N-1 Gila-Sonora 69 kv line SONORA % 8.40% SNLWALCX % 7.90% Case Page 21

23 3.3 Flicker Analysis 2014 Heavy Summer Case Results of the voltage flicker analysis indicate that there are no deviations greater than 1.5%. Table 3.13 details the results of the voltage flicker analysis. The greatest flicker is observed at the Foothills 69.0 kv bus with a % decrease with Q217. This occurs as the unit(s) adjusts from 100% to 10% output. Table 3.13 Flicker Results, Q % Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus (pu) (pu) Deviation (pu) Deviation (pu) Deviation (pu) Deviation FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV LAGUNA 69.00kV FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV Page 22

24 2014 Heavy Summer Case w/high Yuma Load/Gen Results of the voltage flicker analysis indicate that there are no deviations greater than 1.5%. Table 3.14 details the results of the voltage flicker analysis. The greatest flicker is observed at the Foothills 69.0 kv bus with a % decrease with Q217. This occurs as the unit(s) adjusts from 100% to 10% output. Table 3.14 Flicker Results, Q % Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus (pu) (pu) Deviation (pu) Deviation (pu) Deviation (pu) Deviation FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV LAGUNA 69.00kV FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV Page 23

25 2014 Heavy Summer Case w//2016 configuration Results of the voltage flicker analysis indicate that there are no deviations greater than 1.5%. Table 3.15 details the results of the voltage flicker analysis. The greatest flicker is observed at the Foothills 69.0 kv bus with a % decrease with Q217. This occurs as the unit(s) adjusts from 100% to 10% output. Table 3.15 Flicker Results, Q % Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus (pu) (pu) Deviation (pu) Deviation (pu) Deviation (pu) Deviation FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV LAGUNA 69.00kV FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV Page 24

26 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen Results of the voltage flicker analysis indicate that there are no deviations greater than 1.5%. Table 3.16 details the results of the voltage flicker analysis. The greatest flicker is observed at the Foothills 69.0 kv bus with a % decrease with Q217. This occurs as the unit(s) adjusts from 100% to 10% output. Table 3.16 Flicker Results, Q % Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus (pu) (pu) Deviation (pu) Deviation (pu) Deviation (pu) Deviation FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV LAGUNA 69.00kV FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV Page 25

27 2014 Heavy Summer Case w//2016 configuration, High Yuma Load/Gen, TS8 project Results of the voltage flicker analysis indicate that there are no deviations greater than 1.5%. Table 3.17 details the results of the voltage flicker analysis. The greatest flicker is observed at the Foothills 69.0 kv bus with a % decrease with Q217. This occurs as the unit(s) adjusts from 100% to 10% output. Table 3.17 Flicker Results, Q % Generation (base) 10% Generation 30% Generation 60% Generation 90% Generation Bus (pu) (pu) Deviation (pu) Deviation (pu) Deviation (pu) Deviation FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV LAGUNA 69.00kV FOOTHILS 69.00kV N.GILA 69.00kV REDONDO 69.00kV MITTRY 69.00kV ARABY S 69.00kV MAB S 69.00kV SANGUINE 69.00kV GILA 69.00kV SONEILL 69.00kV PACIFIC 69.00kV SW kV QUECHAN 69.00kV WALDRIP 69.00kV SANLUIS 69.00kV Page 26