Request #54. San Manuel 115kV Interconnection. Feasibility Study. APS Contract No Arizona Public Service Company Transmission Planning

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1 A subsidiary of Pinnacle West Capital Corporation Request #54 San Manuel 115kV Interconnection Feasibility Study APS Contract No By Arizona Public Service Company Transmission Planning June 18, 2009 Prepared by Utility System Efficiencies, Inc.

2 Request #54 Feasibility Study Prepared by Utility System Efficiencies, Inc. TABLE OF CONTENTS 1 RESULTS & FINDINGS General Overview Study Description Basecases Flow Distribution of Project s Output Power Flow Analysis Thermal Loading Results: 2012 Heavy Summer Conditions Thermal Loading Results: 2018 Heavy Summer Conditions Voltage Results: 2012 Heavy Summer Conditions Voltage Results: 2018 Heavy Summer Conditions Generation Mitigation Transmission Mitigation Short-Circuit Duty Analysis Mitigation and Estimated Cost San Manuel 115kV Interconnection Cost San Manuel 115kV Network Cost (Analysis suspended by agreement with customer) Conclusions STUDY ASSUMPTIONS Pre-Project Power Flow Case Modeling Pre-Project Power Flow Case Modeling and 2018 Post-Project Power Flow Case Modeling STUDY METHODOLOGY Power Flow Short-Circuit Duty LIST OF APPENDICES Appendix A - List of Contingencies Appendix B Power Flow Plots Page i

3 Q54 Feasibility Study APS Contract No June 18, RESULTS & FINDINGS 1.1 General Overview Arizona Public Service Company ( APS ) received a valid large generator interconnection request for a proposed interconnection at San Manuel Substation. On behalf of, and with the oversight of APS, Utility System Efficiencies, Inc. ( USE ) performed a Feasibility Study ( FeS ) under the APS Tariff. The interconnection request was assigned queue position #54. The Applicant proposes to add solar thermal generation with a maximum net output of 352MW, connected to the San Manuel 115kV bus. The Project is anticipated to achieve commercial operation in the spring of The Customer originally requested that the proposed Project be considered and studied as both an Energy Resource ( ER ) and as a Network Resource ( NR ) Interconnection. Initial study findings uncovered a large cost associated with numerous required Transmission System upgrades associated with interconnecting as a NR. Under the APS OATT LGIP Section 4.4 (Modifications), APS notified the applicant of our early findings and offered that APS would, at the Customer's request, stop that aspect of the study and cease accumulating Customer study cost obligations in that regard. By written notice ( ) the Customer subsequently withdrew their request for NR Interconnection Service to be studied within the subject Feasibility Study. APS agreed to study the Project solely as an ER Interconnection Service. APS has elected to initially conduct a Feasibility Study to determine what potential impact (if any), this Project s interconnection may have on the APS interconnected transmission and local sub-transmission system. This Feasibility Study assumed a 2012 Heavy Summer condition for study purposes. Summary of Results This Feasibility Study identified that mitigation or curtailment is required for the Project s interconnection. Three reliability concerns were identified with a total estimated cost of $16.05M for mitigation projects to address these concerns. The estimated total cost of interconnection facilities is $500K. The total interconnection costs are therefore estimated to be $16.55M. Rather than system upgrades the Applicant may elect to curtail the output of the generation by as much as 42MW (curtailment may vary depending on the scenario, see Table 6) to a total net output of 310MW (worst case). The results are not significantly impacted by the Tortolita-Pinal Central 500kV line. In addition, the Cholla-Pinnacle Peak 500kV line conceptual project and associated interconnection requests APS Q#37, APS Q#53, and SRP Q#3 did not have any adverse effects upon this interconnection. Nothing in this report constitutes an offer of transmission service or confers upon the Applicant 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. The interconnection is in close electrical proximity to facilities and/or transmission rights of the following neighboring entities: Salt River Project ( SRP ), Tucson Electric Power ( TEPC ), Southwest Transmission Cooperative ( SWTC ), and Western Area Power Administration Lower Colorado ( WALC ). Because of potential impact, all of these entities are also considered Affected Utilities. Should the Project proceed with the Large Generator Interconnection Process ( LGIP ), these Affected Utilities will be notified of this proposed interconnection and encouraged to comment and/or provide up-to-date data pertaining to the potential impact to their system(s). For this initial Feasibility Study, only publiclyavailable data was used in modeling system conditions for the neighboring Affected Utility system(s). A more detailed analysis could be performed with additional data supplied by the Affected Utilities during the System Impact Study ( SIS ) phase. For this Generator Interconnection the customer invited SWTC to participate in the Feasibility Study from the outset. Also, subsequent to the start of the study work the customer requested APS to engage with TEP. Both SWTC and TEP were consulted in regards to determining the various dispatch scenarios and Page 2

4 Q54 Feasibility Study APS Contract No June 18, 2009 which generators to displace. Also, a draft of the study results were shared with SWTC and TEP and their comments and input were incorporated into this version of the study report. 1.2 Study Description This study determined the Project s impact on the APS interconnected transmission system and the associated transmission reinforcements that would be required to interconnect the Project. The following technical analyses were studied as part of the FeS: A. Power flow analysis B. Short circuit analysis Performance of the transmission system was measured against the WECC Reliability Criteria and NERC Planning Standards. A subsequent System Impact Study of the Project may include additional analyses such as: Transient Stability analysis, Post-Transient voltage stability and possibly reactive margin analysis, voltage flicker analysis, and Subsynchronous Resonance ( SSR ) analysis. The following nearby generation Interconnection Requests ahead in the queue were modeled in the short circuit analysis and were not modeled in the power flow analysis because the applicants have elected to be Energy only Resources ( ER ): APS Q#37 300MW at Cholla 500kV as NR and ER in 2010, assumed ER without the Cholla- Pinnacle Peak 500kV line modeled. APS Q#53 375MW at Cholla 345kV as NR and ER in 2011, assumed ER without the Cholla- Pinnacle Peak 500kV line modeled. SRP Q#3 700MW at Coronado 500kV as NR and ER in 2012, assumed ER. APS Q#31 102MW at Gila Bend 69kV as ER in The following nearby generation Interconnection Requests ahead in the queue will be modeled in the short circuit analysis, and in the power flow analysis because they have either elected to be studied as both an Energy only Resource ( ER ) and a Network Resource ( NR ) or simply as a NR: APS Q#44 280MW at Gila Bend 230kV as NR in APS Q#45 250MW at Gila Bend 23kV as NR and ER in APS Q#51 200MW at Hyder area 69kV as NR in Sensitivity cases will be run to assess the impacts of relatively uncertain but significant transmission characteristics: Tortolita-Pinal Central 500kV Line Sensitivity: Identify the reliability impacts with and without the Tortolita-Pinal Central 500kV Line. Schedule cluster output to PV Hub/APS/SRP for all cases: Identify the reliability impacts for these various scheduling scenarios. In addition, a 2018 sensitivity case will be run to assess the impact of the conceptual Cholla-Pinnacle Peak 500kV transmission capacity project which will benefit the NR interconnection of: APS Q#37 300MW at Cholla 500kV as NR and ER in APS Q#53 375MW at Cholla 345kV as NR and ER in SRP Q#3 700MW at Coronado 500kV as NR and ER in These units will be assumed online for this sensitivity. Page 3

5 Q54 Feasibility Study APS Contract No June 18, Basecases A family of 12 basecases were created to properly study each sensitivity. The cases were each built from the 2013 summer WestConnect Detailed Planning basecase. This case was jointly constructed by the Arizona utilities, represents the most up-to-date transmission system topology, and includes the most recent APS load forecast for The basecase topology and load were adjusted to reflect 2012 summer conditions. In addition, a 2018 basecase was created that models the Cholla-Pinnacle Peak 500kV line concept project. These cases were built from the 2018 heavy summer WestConnect Bulk Planning basecase. As with the 2013 case, this 2018 case was jointly constructed by the Arizona utilities. Three dispatch scenarios were studied to understand the reliability impacts of sending the power in various directions. The first scenario was to send the power to the Palo Verde Hub where Redhawk generation was reduced to offset the new generation. The second scenario was to send to the power to the nearest APS delivery point where Saguaro generation was reduced. The third scenario was to send the power to SRP where Santan generation was reduced. Table 1 summarizes the cases utilized in this study. Table1. Basecase Modeling Summary # Scenario Description 2012 Heavy Summer 1. Pre Project 2. Post Project (PV) 3. Post Project (APS) 4. Post Proejct (SRP) 5. Pre Project, No Tortolita-Pinal South 500kV Line 6. Post Project, No Tortolita-Pinal South 500kV Line (PV) 7. Post Project, No Tortolita-Pinal South 500kV Line (APS) 8. Post Project, No Tortolita-Pinal South 500kV Line (SRP) 2018 Heavy Summer 9. Pre Project 10. Post Project (PV) 11. Post Project (APS) 12. Post Project (SRP) Tortolita-Pinal South 500kV Line PV Hub (Redhawk) Sink APS (Saguaro) SRP (Santan) Cholla-Pinnacle Peak 500kV Line APS Q#37, APS Q#53, SRP Q#3 Page 4

6 Q54 Feasibility Study APS Contract No June 18, Flow Distribution of Project s Output This section summarizes the changes observed in normal power flows for local branches and Paths, after the introduction of the Project. For interconnection at the proposed locations, the Project has a potential impact to the following WECC Paths: #50 and #54. For this analysis, the study case modeled these Paths at a moderate level of stress/flows. Under higher/alternately stressed conditions, the Project s output could potentially trigger a system upgrade or be restricted due to system operating limits associated with these Paths/systems. Should the Project proceed to a System Impact Study, it may be desirable to examine sensitivity case(s) with one or more of these Paths under a maximized loading condition. Table 2 and Table 3 provides a comparison of change in MW flows for local Paths and branches in the Pre-Project and resulting Post-Project cases, under normal conditions for the 2012 and The Cholla-Pinnacle Peak 500kV line conceptual project will create transmission capacity that can benefit interconnection requests APS Q#37, APS Q#53, and SRP Q#3. This project is purely conceptual in nature, and APS has not made any plans construct this line. It is assumed that a 500kV line of this nature can be permitted and constructed at the earliest by A second set of basecases that model the 2018 transmission system under heavy summer conditions has been developed to properly analyze the effect, if any, on this interconnection. Table Pre-Project and Post-Project Power Flow Case Attributes (MW) Major Path/Branch Flows (MW): Normal Rating (MVA) All Planned Projects In Service Pre- Project PV APS SRP No Tortolita-Pinal Central 500kV Line Pre- Project PV APS SRP Path 50: Cholla-Pinnacle Peak (345kV) Path 54: Coronado-Silver King* ,064 1,069 1,062 1,075 1,029 1,055 1,017 1,056 Cholla-Saguaro 500kV Line (series cap.) Saguaro-Tortolita #1 or #2 500kV Line Tortolita-Pinal Central 500kV Line San Manuel-Apache 115kV Line San Manuel-Saddlebrooke Ranch 115kV Line San Manuel-Saguaro 115kV Line San Manuel-Hayden 115kV Line Oracle-Tucson 115kV Line Oracle-Coolidge 115kV Line Saguaro 500/115kV Xfmr. #4 or # Saguaro 230/115kV Xfmr. #1 or # Arizona Area 14 (incl. WALC) Load -- 21,915 21,947 21,947 21,945 21,915 21,947 21,947 21,945 Losses Generation -- 30,560 30,601 30,603 30,602 30,562 30,603 30,607 30,604 Interchange (+ exports, - imports) -- 7,780 7,779 7,779 7,779 7,780 7,780 7,780 7,780 * Path 54 WECC Phase III rating of 1494MVA from 2008 WECC Path Rating Catalog. Case Page 5

7 Q54 Feasibility Study APS Contract No June 18, 2009 Table Pre-Project and Post-Project Power Flow Case Attributes with Conceptual Project (MW) Major Path/Branch Flows (MW): Normal Rating (MVA) Pre- Project Post-Project PV APS SRP Path 50: Cholla-Pinnacle Peak (345kV) Path 54: Coronado-Silver King* ,109 1,106 1,107 1,116 Cholla-Pinnacle Peak 500kV Line (Concept) 2598/2598 1,066 1,097 1,065 1,080 Cholla-Saguaro 500kV Line (series cap.) Saguaro-Tortolita #1 or #2 500kV Line Tortolita-Pinal Central 500kV Line San Manuel-Apache 115kV Line San Manuel-Saddlebrooke Ranch 115kV Line San Manuel-Saguaro 115kV Line San Manuel-Hayden 115kV Line Oracle-Tucson 115kV Line Oracle-Coolidge 115kV Line Saguaro 500/115kV Xfmr. #4 or # Saguaro 230/115kV Xfmr. #1 or # Arizona Area 14 (incl. WALC) Load -- 26,324 26,356 26,356 26,353 Losses Generation -- 34,983 35,028 35,026 35,025 Interchange (+ exports, - imports) -- 7,917 7,917 7,917 7,917 Case * Path 54 WECC Phase III rating of 1494MVA from 2008 WECC Path Rating Catalog. Addition of the Cholla-Pinnacle Peak 500kV line will likely raise the limit and potentially become a part of the path definition. The path flows reported in this table are limited to the existing definition. 1.5 Power Flow Analysis All power flow results for the Project are dependent upon the assumed topology in the vicinity of San Manuel/Saguaro substations, which is subject to change. When this FeS commenced, the most recent APS transmission plan was used. APS transmission system is continuously being evaluated; planned reinforcements and their in-service dates are often revised depending upon local area load growth. Should the Project proceed with the LGIP, at the commencement of the System Impact Study the most recent available APS plan will be used for proposed reinforcements and their timing Thermal Loading Results: 2012 Heavy Summer Conditions Table 4 details the system power flow increases caused by the Project. The orange shading indicates the element is overloaded. The power flow contingency analysis identified that for the three interconnection scheduling options (at full output of 352MW) the Project can potentially cause or worsen overloads of transmission elements in the Arizona system. These contingency overload concerns are further discussed below. For the studied cases, several contingencies (remote from the Project s Point of Interconnection) resulted in overloads in the Pre-Project case; these selected outages were recognized as remote, localized thermal issues unrelated to the Project. The overloads triggered by these contingencies were not affected by the proposed (post-project) generation addition; therefore, subsequent reporting for these outages has been omitted from the results tables. Thermal results for the following outages were deemed non-relevant for the proposed generation project: Page 6

8 Q54 Feasibility Study APS Contract No June 18, 2009 BLKMSA34 230/69kV Xfmr 1 FLAGSTAF-GLENCANY 345kV Line 1 BLKMSA34 230/69kV Xfmr 2 FLAGSTAF-GLENCANY 345kV Line 2 RIVIERA 230/69kV Xfmr 1 JOJOBA-TS4-LIBERTY/PALMVLY 230kV Line RIVIERA 230/69kV Xfmr 2 DOSCONDO 230/69kV Xfmr 1 LINDEN-HEBERTP-ZENIFF 69kV Line DOSCONDO 230/69kV Xfmr 2 GLENCANY 345/230kV Xfmr 1 SNOWFLAK-SGRLF 69kV Line GLENCANY 345/230kV Xfmr 2 SNOWFLAK-SGRLF 69kV Line (add Shumway shunt) WILOWLKE-YAVAPAI 230kV Line (W XFMR 6) FLAGSTAF-PINPKBRB 345kV Line 1 JOJOBA-PANDA 230kV Line FLAGSTAF-PINPKBRB 345kV Line 2 MEAD S 230/69kV Xfmr 1 PRESCOTT 230/115kV Xfmr 1 JOJOBA-KYRENE 500KV Line PRESCOTT 230/115kV Xfmr 2 BUCKEYE 230/69kV Xfmr 1 PALMVLY 230/69kV Xfmr 1 BUCKEYE 230/69kV Xfmr 2 Table 4. Thermal Loading Results, 2012 Heavy Summer Case CONTINGENCY / AFFECTED ELEMENTS Normal/ Emerg. Rating (MVA) N-1 Pinnacle Peak (WAPA)-Pinnacle Peak (SRP) 230kV Line 2 All Planned Projects In Service Pre- Project PV APS SRP Pre- Project No Tortolita-Pinal Central 500kV Line PV APS SRP PP (WALC)-PP (SRP) 230kV Line 1 (WALC) 362/ % 140.2% 141.4% 144.6% 139.1% 139.7% 140.1% 143.8% N-1 Palo Verde-Rudd 500KV Line 1 Liberty-Hassayampa Tap 230kV Line 1 (WALC) 319/ % 103.2% 106.7% 107.7% 107.0% 103.3% 107.3% 109.3% N-1 San Manuel-Saddlebrooke Ranch115kV Line San Manuel-Hayden 115kV Line 124/136 < 80% 110.4% 105.5% 109.3% < 80% 109.3% 102.2% 108.4% N-1 Oracle-Saddlebrooke Ranch 115kV Line San Manuel-Hayden 115kV Line 124/136 < 80% 104.2% 99.3% 103.7% < 80% 103.1% 96.0% 102.2% N-1 San Manuel-Hayden 115kV Line Oracle-Saddlebrooke Ranch 115kV Line 145/145 < 80% 102.9% 103.5% 103.4% < 80% 102.6% 102.9% 103.0% San Manuel-Saddlebrooke Ranch 115kV Line 180/180 < 80% 95.2% 95.7% 95.6% < 80% 95.1% 95.5% 95.4% N-1 Silverking 500/230kV Xfmr 1 San Manuel-Hayden 115kV Line 124/136 < 80% 100.7% 94.5% 100.2% < 80% 99.4% 90.7% 98.4% N-1 Saguaro-San Manuel 115kV Line Oracle-Saddlebrooke Ranch 115kV Line 145/145 < 80% 90.9% 97.1% 92.3% < 80% 91.4% 99.2% 93.1% San Manuel-Hayden 115kV Line 124/136 < 80% 94.6% 90.2% 94.2% < 80% 93.4% 86.9% 92.6% Case Page 7

9 Q54 Feasibility Study APS Contract No June 18, Thermal Overloads: 2012 Heavy Summer Conditions Two pre-existing overloads are noted in Table 4 upon which the Project demonstrated an effect. The following reliability issues are observed in the Pre-Project cases: 1. An outage of either Pinnacle Peak WAPA-Pinnacle Peak SRP 230kV line overloads the remaining line. 2. An outage of the Palo Verde-Rudd 500kV line overloads the Liberty-Hassayampa Tap 230kV line. Both of these outages create overloads that are observed in previous studies and solutions are either currently being studied or have been identified. Also, the change in loading observed on those lines are more closely related to the generation that was displaced than it is to the Q54 project. Therefore, these overloads will not be attributable to the Q54 project. The 115kV transmission system in and around San Manuel substation is adversely affected by the interconnection. Various N-1 outages overload the San Manuel outlet lines. The worst of which is an outage of the San Manuel-Saddlebrooke Ranch 115kV line loading the San Manuel-Hayden 115kV line to 110.4% (worst case PV). This line has an emergency rating of 136MVA. The San Manuel 115kV system does not appear to be significantly affected by the presence of the Tortolita-Pinal Central 500kV line. In addition to the San Manuel-Hayden 115kV line, the Oracle-Saddlebrooke Ranch 115kV line can become overloaded following an outage of the San Manuel-Hayden 115kV line (103.5% worst case - APS) Thermal Loading Results: 2018 Heavy Summer Conditions Table 5 details the system power flow increases caused by the interconnection. The orange shading indicates the element is overloaded. For the studied cases, several contingencies (remote from the Project s Point of Interconnection) resulted in overloads in the Pre-Project case; these selected outages were recognized as remote, localized thermal issues unrelated to the Project. The overloads triggered by these contingencies were not affected by the proposed (post-project) generation addition; therefore, subsequent reporting for these outages has been omitted from the results tables. Thermal results for the following outages were deemed non-relevant for the proposed generation project: BLKMSA34 230/69kV Xfmr 1 AVRA-MARANA 115kV Line BROWNING 230/69kV Xfmr 1 AVRA-SNDARIO 115kV Line BLKMSA34 230/69kV Xfmr 2 WESTWING 500/230kV Xfmr 1 RIVIERA 230/69kV Xfmr 1 YAVAPAI 500/230kV Xfmr 1 RIVIERA 230/69kV Xfmr 2 YAVAPAI 500/230kV Xfmr 2 PRESCOTT 230/115kV Xfmr 2 ALEXANDR 230/69kV Xfmr 1 PRESCOTT 230/115kV Xfmr 1 ALEXANDR 230/69kV Xfmr 2 WARD 230/69kV Xfmr 1 WPHXAPSS 230/69kV Xfmr (S) WARD 230/69kV Xfmr 2 WPHXAPSS 230/69kV Xfmr (N) GILARIVR 500/230kV Xfmr 1 WPHXAPSS 230/69kV Xfmr (C) SANTAN 230/69kV Xfmr 3-5 CORBELRS 230/69kV Xfmr 2 & 3 KNOB-PILOTKNB 161kV Line GOLDFELD-HORSMESA 115kV Line MILLIGAN 230/69kV Xfmr 1 GLENCANY 345/230kV Xfmr 1 ANDERSRS 230/69kV Xfmr 1 GLENCANY 345/230kV Xfmr 2 ANDERSRS 230/69kV Xfmr 2 ORME RS 230/69kV Xfmr 1 ANDERSRS 230/69kV Xfmr 3 ORME RS 230/69kV Xfmr 2 ANDERSRS 230/69kV Xfmr 4 ORME RS 230/69kV Xfmr 3 FLAGSTAF-GLENCANY 345kV Line 1 ORME RS 230/69kV Xfmr 4 FLAGSTAF-GLENCANY 345kV Line 2 CORBELL-KYRENE 230kV Line JOJOBA-TS4-LIBERTY/PALMVLY 230kV Ckt. BRANDOW-WARD 230kV Line 1 JOJOBA-PANDA 230kV Line BRANDOW-WARD 230kV Line 2 CACTUS-OCOTILLO 230kV Line Page 8

10 Q54 Feasibility Study APS Contract No June 18, Thermal Overloads: 2018 Heavy Summer Conditions As with the 2012 case, an outage of either Pinnacle Peak WAPA-Pinnacle Peak SRP 230kV line overloads the remaining line in the Pre-Project case, indicating a pre-existing issue. The 115kV transmission system in and around San Manuel substation remains adversely affected by the interconnection. The worst outage is still of the San Manuel-Saddlebrooke Ranch 115kV line loading the San Manuel-Hayden 115kV line to 106.2% (worst case PV). The magnitude of the overload is slightly less than the 2012 case primarily due to the increase in San Manuel load (19MW up from 9MW in 2012). Table 5. Thermal Loading Results, 2018 Heavy Summer Case with Cholla-Pinnacle Peak 500kV line Conceptual Project CONTINGENCY / AFFECTED ELEMENTS Normal/ Emerg. Rating (MVA) Pre- Project Post-Project Primary POI PV APS SRP N-1 Pinnacle Peak (WAPA)-Pinnacle Peak (SRP) 230kV Line 2 PP (WALC)-PP (SRP) 230kV Line 1 (WALC) 362/ % 125.5% 125.2% 126.5% N-1 San Manuel-Saddlebrooke Ranch 115kV Line San Manuel-Hayden 115kV Line 124/136 < 80% 106.2% 102.1% 105.9% N-1 Oracle-Saddlebrooke Ranch 115kV Line San Manuel-Hayden 115kV Line 124/136 < 80% 97.0% 92.9% 96.8% Case Voltage Results: 2012 Heavy Summer Conditions Results indicate that at full output 1 (352MW), interconnection of the Project (at either location) does not cause any new voltage violations. However, the system s voltage deviation performance is slightly worsened at several 69kV busses in APS northern system served out of the Cholla substation. Some resulting emergency voltages fell outside the prescribed performance criteria; however, these criteria violations occurred for both the pre-project and post-project conditions. Furthermore, for most of these outages the voltage deviations are mitigated by subsequent operator actions to close the Vernon 69kV tie and/or inserting shunt capacitors at Shumway or Show Low. Therefore, no attributable voltage impact has been associated with the Project. 1 Output under normal conditions was assumed near unity at the generator terminals. Page 9

11 Q54 Feasibility Study APS Contract No June 18, 2009 For the studied cases, several contingencies (remote from the Project s point of interconnection) resulted in either voltage violations or divergence of the power flow solution; these selected outages were recognized as remote and/or localized voltage issues unrelated to the Project. System voltage performance for these contingencies was not affected by the proposed (post-project) generation addition; therefore, subsequent reporting for these outages has been omitted from the results tables. Results for the following outages were deemed non-relevant for the proposed generation project: - WILOWLKE-YAVAPAI 230kV Line (W XFMR 6) - HACKBERY-MORENCI 230kV Line - SGRLF 500/69kV Xfmr (close Vernon tie + caps) - SURPRISE 230/69kV Xfmr 1 - LINDEN-HEBERTP-ZENIFF 69kV Ckt - PNPKAPS 230/69kV Xfmr 6 - SNOWFLAK-SGRLF 69kV Line - PNPKAPS 230/69kV Xfmr 17 - SNOWFLAK-SGRLF 69kV Line (add Shumway shunt) - SGRLF-ZENIFF 69kV Line - SHOWLOW-SHUMWAY 69kV Line (close Vernon tie) - WHTNKAPS 230/69kV Xfmr (N) - COCONINO-VM1 69kV Line - APACHE-RED TAIL 230kV Line - COCONINO-VM1 69kV Line (w/capital Butte shunts) - MARANATP-MARANA 115kV Line - COCONINO-SWITZER 69kV Line (w/tuba City shunt) - WESTWNGE 230/69kV Xfmr 1 - ELDEN N-SANDVIG 69kV Line (w/tuba City shunt) - WESTWNGE 230/69kV Xfmr 2 - VM1-KACHVILL 69kV Line - GATEWAY 345/138kV Xfmr 1 - VM1-KACHVILL 69kV Line (w/capital Butte shunts) - GATEWAY-VALNCIA 138kV Line - WILOWLKW-PRESCOTT 230kV Line 1 (W XFMR 10) - RED TAIL-DOSCONDO 230kV Line - CHLCONST-CHOLLA2 69kV Line - OCOTILLO 230/69kV Xfmr 1 - TS6 230/69kV Xfmr Voltage Results: 2018 Heavy Summer Conditions Results indicate that at full output 2 (352MW), interconnection of the Project (at either location) does not cause any new voltage violations. However as with the 2012 case, the system s voltage deviation performance is slightly worsened at several local 69kV busses. Some resulting emergency voltages fell outside the prescribed performance criteria; however, these criteria violations occurred for both the preproject and post-project conditions. Therefore, no attributable voltage impact has been associated with the Project. For the studied cases, several contingencies (remote from the Project s point of interconnection) resulted in either voltage violations or divergence of the power flow solution; these selected outages were recognized as remote and/or localized voltage issues unrelated to the Project. System voltage performance for these contingencies was not affected by the proposed (post-project) generation addition; therefore, subsequent reporting for these outages has been omitted from the results tables. Results for the following outages were deemed non-relevant for the proposed generation project: - MOONSHIN-PINAL 115kV Line - PRESCOTT 230/115kV Xfmr 1 - RAY-SUPERIOR 115kV Line - PRESCOTT 230/115kV Xfmr 2 - PINPK-GAVLINWA 230kV Line - APACHE-RED TAIL 230kV Line - BLKMSA34 230/69kV Xfmr 1 - APACHE-BUTERFLD 230kV Line - BLKMSA34 230/69kV Xfmr 2 - GRIFFTH1 Unit 1 - WARD 230/69kV Xfmr 1 & 2 - HILLTOP-MCCONICO 230kV Line - SILVERKG 500/230kV Xfmr 1. 2 Output under normal conditions was assumed near unity at the generator terminals. Page 10

12 Q54 Feasibility Study APS Contract No June 18, Generation Mitigation As outlined in section thermal overloads exist in the power flow simulation. This section will detail the generation curtailments required to fully mitigate these reliability issues without any transmission upgrades applied. One important note is the curtailment levels assume peak load. The San Manuel- Hayden 115kV line overload is adversely affected by a reduction in load Generation Mitigation #1: San Manuel-Hayden 115kV Line Condition 1: 2012, With or Without Tortolita-Pinal Central 500kV, power scheduled to APS, SRP, or PV. An outage of the APS s San Manuel-Saddlebrooke Ranch 115kV line overloads the San Manuel- Hayden 115kV line when power is scheduled to APS, SRP, or the Palo Verde Hub. The line potentially loads to 110.4% when scheduled to PV, 105.5% when scheduled to APS, and 109.9% when scheduled to SRP. This issue is not significantly affected by the status of the Tortolita-Pinal Central 500kV line Generation Curtailments Table 6 indicates the maximum allowable output for the various scheduling scenarios without any transmission upgrades applied. These values are at peak summer loading conditions and may be different for off-peak conditions. Off-peak conditions may be more closely evaluated if Q54 proceeds to a SIS. Table 6. Curtailed Generation Levels to Mitigate Thermal Loading Concerns Scheduling Breakdown PV APS SRP Limiting Contingency Limiting Element 2012 With the Tortolita-Pinal Central 500kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line 2012, No Tortolita-Pinal Central 500kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line 2018 With Cholla-PP 500kV Project N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line N-1 San Manuel- Saddlebrooke Ranch 115kV Line. San Manuel-Hayden 115kV Line Page 11

13 Q54 Feasibility Study APS Contract No June 18, Transmission Mitigation This section discusses the potential transmission upgrade projects needed to mitigate the overloads caused by the interconnection. Implementing these projects will relieve the Project of any of the curtailments outlined in Table 6 in the previous section. Table 7 details the trigger points at which each upgrade is required to achieve full project output. Transmission Mitigation #1: San Manuel 115kV Upgrades Condition 1: 2012 Heavy Summer, power scheduled to SRP, APS, or PV Hub The first mitigation options to alleviate the overloads is to re-conductor the San Manuel-Hayden 115kV line and add an emergency rating to the Oracle-Saddlebrooke Ranch 115kV line. If an emergency rating cannot be implemented the line will need to be re-conductored as well. Table 7. Upgrade Requirements for Project Output Levels Scheduled to: PV APS SRP Upgrade Requirement 2012, with the Tortolita-Pinal Central 500kV Line No Upgrades Required San Manuel-Hayden 115kV line upgrade Oracle-Saddlebrooke Ranch 115kV line upgrade 2012, No Tortolita-Pinal Central 500kV Line No Upgrades Required San Manuel-Hayden 115kV line upgrade Oracle-Saddlebrooke Ranch 115kV line upgrade 2018, With the Cholla-Pinnacle Peak 500kV Line No Upgrades Required San Manuel-Hayden 115kV line upgrade Page 12

14 Q54 Feasibility Study APS Contract No June 18, Short-Circuit Duty Analysis Short circuit analysis of the proposed generator interconnection(s) was performed by the APS Protection Department, using the CAPE program and parameters supplied by the Applicant. Fault duties were calculated for both single-phase-to-ground and three-phase faults at substation busses in the immediate surrounding area before and after the proposed generator installation. The results presented here assume a worst-case scenario, with all of the Project s generating units assumed on-line. Results of the short circuit duty analysis (Table 8) indicate the interconnection overstresses the minimum breaker at San Manuel substation. The rating information of one of the surrounding substations is unknown at this time. That substation is owned and operated by SRP. The rating information for the substations owned and operated by APS, SWTC, TEP, and WAPA have been included after consultation with those utilities. This portion of the study will require close coordination with the neighboring utilities should the applicant proceed to the System Impact Study phase of the LGIP. Substation Bus Table Short-Circuit Results Pre-Project 3 Ph. (ka) Ph-G (ka) Post-Project 3 Ph. (ka) Ph-G (ka) Minimum Breaker Rating (ka) San Manuel 115kV Hayden 115kV Non-APS Saddlebrooke Ranch115kV Oracle Junction 115kV Saguaro 115kV Coolidge 115kV Apache 115kV Further analysis of San Manuel substation reveals that circuit breaker 318 will need to be upgraded to accommodate the interconnection. This breaker exceeds its rated capacity by 723 Amps. The other circuit breakers in the station have sufficient breaker margin and do not require any upgrade. APS has obtained the minimum breaker ratings at most of the non-aps substations for the FeS. However, a more detailed and collaborative short-circuit impact will be studied if Q54 proceeds to SIS. Page 13

15 Q54 Feasibility Study APS Contract No June 18, Mitigation and Estimated Cost Mitigation and costs listed here are grouped into two parts: 1) basic costs for the interconnection itself, per the proposed interconnection voltage level; and 2) costs for Network Resource integration that is, reinforcements required to allow the full scheduling of the Project s 352MW to the APS load San Manuel 115kV Interconnection Cost Based on the results of this initial Feasibility Study, the San Manuel-Hayden 115kV line and possibly the Oracle-Saddlebrooke Ranch 115kV line will need to be re-built. A rough, non-binding cost estimate for this interconnection work is as follows: San Manuel 115kV Substation Costs...$ 0.5M Connection of the Project to the San Manuel 115kV bus, including one 115kV circuit breaker, switches, potential transformers, metering, and protection. Does not include any associated land costs that may be incurred. Saddlebrooke Ranch-Oracle 115kV Line upgrade...$ 3.0M Re-build 3 miles of the Saddlebrooke Ranch-Oracle 115kV line with new structures a higher rated conductor. 795 ACSR is assumed to be utilized. San Manuel-Hayden 115kV Line upgrade...$ 12.9M Provided by SWTC: Rebuild 28.2 miles of San Manuel-Hayden 115kV line with new structures and a higher rated conductor ACSR is assumed to be utilized. San Manuel Circuit Breaker 318 Replacement...$ 0.15M Replace San Manuel 115kV circuit breaker 318 with a higher capacity unit. Total Interconnection Costs...$ 16.55M San Manuel 115kV Network Cost (Analysis suspended by agreement with customer) The initial Interconnection Request from Q54 was for both Network and Energy Interconnection. As APS evaluated the system upgrades that would be required to deliver Q54 to APS retail load the upgrades that would be required were substantial. This preliminary analysis was communicated to the customer and the customer requested to suspend the Network Resource Interconnection portion and proceed only with an Energy Resource Interconnection. The following is a list of facilities that would need to be upgraded for Q54 to be able to deliver to APS as a network resource: San Manuel-Saguaro 115kV line rebuild (approx. 40 miles) Additional Saguaro 115/230kV transformer New/rebuilt Saguaro 230kV substation Saguaro-Santa Rosa 230kV line rebuild (approx. 61 miles) Santa Rosa-Knox-Kyrene 230kV line rebuild (approx. 30 miles) Kyrene-Ocotillo 230kV line rebuild or 2 nd circuit (approx. 22 miles) 1.8 Conclusions This Feasibility Study identified that mitigation or curtailment is required for the Project s interconnection. The most limiting constraint is the San Manuel-Hayden 115kV line that can overload following an outage of the San Manuel-Saddlebrooke Ranch 115kV line. A second constraint that will require mitigation in order to achieve full output is an overload of the Oracle-Saddlebrooke Ranch 115kV line following an outage of the San Manuel-Hayden 115kV line. The third and final reliability concern identified in this study is the new generation can overstress the San Manuel 115kV circuit breaker 318. All three reliability concerns apply under all three generation dispatch scenarios. The total cost of mitigation projects to Page 14

16 Q54 Feasibility Study APS Contract No June 18, 2009 address these concerns is estimated to be $16.05M. In addition the estimated cost of interconnection facilities needed at the San Manuel substation is $500K. Rather than system upgrades the Applicant may elect to curtail the output of the generation. The curtailment is 42MW at the worst case (scheduled to the PV Hub with the Tortolita-Pinal Central 500kV line in service), or the curtailment can be 12MW at the best case (scheduled to APS without the Tortolita- Pinal Central 500kV line). The results are not heavily impacted by the Tortolita-Pinal Central 500kV line. Removing the line slightly reduces the overload percentages of each identified constraint. In addition, the Cholla-Pinnacle Peak 500kV line conceptual project and associated interconnection requests APS Q#37, APS Q#53, and SRP Q#3 did not have any adverse effects upon this interconnection. 2 STUDY ASSUMPTIONS This section of the report provides details pertaining to the power flow case development and an overview of major study assumptions. Tables 1 and 2 (shown previously in this report) provide a summary/overview of Pre-Project and Post-Project case attributes for the 2012 and 2018 basecase families Pre-Project Power Flow Case Modeling Pre-Project Case, 2012 Heavy Summer The following modifications were applied in the creation of the 2012 pre-project power flow case: a. Study power flow case sm13#08.sav was obtained from APS Transmission Planning. This power flow case had undergone review and updates by all of the Arizona utilities, for Arizona/regional planning purposes. This base case features the Devers-Palo Verde #2 500kV Line (also known as Harquahala Junction-Devers) and the other EOR Combined Projects upgrades expected to increase the East-of-River Path rating to 10,500MW. b. APS transmission projects expected prior to the Project were modeled. Modeled projects and their timing were based on APS Ten-Year Transmission Plan. 3 c. As directed by APS, emergency ratings ( % of normal) were added for selected APS 230/69kV transformers. d. The power flow case included modeling for the Navajo Transmission Project (NTP), a new 500kV line connecting Four Corners, the Desert Rock Energy Project (DREP), and Red Mesa Substation. DREP generation (2x700MW units) was modeled on-line at 1400MW total. e. The power flow case included modeling of the Springerville Unit #4 (430MW, expected 2009). f. Closed the Irvington-Tucson 138kV line, per TEPC. g. Increased the rating of the Irvington-Kino-Tucson 138kV line to 540MVA normal and 606MVA emergency, per TEPC. h. Set the rating of the North Loop-Rillito 138kV line to 382MVA normal and emergency, per TEPC Pre-Project Power Flow Case Modeling Pre-Project Case, 2018 Heavy Summer The following modifications were applied in the creation of the 2018 pre-project power flow case: 3 The APS Ten Year Transmission Plan was posted in early February Page 15

17 Q54 Feasibility Study APS Contract No June 18, 2009 a. Study power flow case catshv_2018_final_aps_r2.sav was obtained from APS Transmission Planning. This base case features the Devers-Palo Verde #2 500kV Line (also known as Harquahala Junction-Devers) and the other EOR Combined Projects upgrades expected to increase the East-of-River Path rating to 10,500MW. b. APS transmission projects expected prior to the Project were modeled. Modeled projects and their timing were based on APS Ten-Year Transmission Plan. 3 c. As directed by APS, emergency ratings ( % of normal) were added for selected APS 230/69kV transformers. d. The power flow case includes the Sun Valley-Raceway 500kV transmission project, anticipated in e. The Cholla-Pinnacle Peak 500kV line capacity project was added to the basecase. Earliest anticipated completion of this project is f. The Pantano 230/115kV transformer was removed. g. Closed the Irvington-Tucson 138kV line, per TEPC. h. Increased the rating of the Irvington-Kino-Tucson 138kV line to 540MVA normal and 606MVA emergency, per TEPC. i. Set the rating of the North Loop-Rillito 138kV line to 553MVA normal and emergency, per TEPC. j. Opened the Kino-Downtown 138kV line, per TEPC and 2018 Post-Project Power Flow Case Modeling Figure 1 provides a high level single line diagram of the Project s interconnection at San Manuel. For the post-project cases, the Project was modeled as follows: Request #54 (352MW net output) is modeled as four 96MW units. Each unit has a dedicated Generator Step-Up ( GSU ) transformer. The GSUs will step the voltage up to 115kV and then a dedicated transmission line will deliver the power to either the San Manuel 115kV substation. Figure 1. Sketch, Q#54 Project Interconnection PINAL CENTRAL To CHOLLA Sensitivity To CASA GRANDE To COOLIDGE To HAYDEN SAN MANUEL SAGUARO SAGUARO CTs SAGUARO 1-2 TORTOLITA ORACLE To Tucson To APACHE Queue #54 (352MW) Page 16

18 Q54 Feasibility Study APS Contract No June 18, STUDY METHODOLOGY This section of the report provides a summary of methods employed for determining the power flow and short circuit results. 3.1 Power Flow All power flow analysis was conducted with version 16.0(_11) of General Electric s PSLF/PSDS/SCSC software. For normal conditions, automatic transformer taps, SVD s and phase-shifting transformers (PST s) were allowed to adjust in solving the power flow case. For contingency simulations, the power flow analysis considers a snapshot in time where automatic transformer taps and SVD s are allowed to adjust, while PST s remain fixed ; in addition, a system swing bus balances the system during each contingency scenario. Power flow results were monitored and reported for APS and other neighboring systems, including (but not limited to) SRP and WAPA. Traditional power flow analysis was used to evaluate thermal and voltage performance of the system under emergency N-1 (single contingency) conditions. Thermal loadings were reported when a modeled transmission component 69kV was loaded over 98% of its appropriate emergency MVA rating (as entered in the power flow database), and the incremental change in component loading, between Pre- Project and Post-Project, exceeded 0.4%. Transmission voltage violations for normal N-0 (no contingency) conditions were reported where per unit voltages were less than 0.95 or greater than Emergency (N-1, single contingency) voltage violations were reported when per unit voltage was less than 0.90 or greater than In addition, voltage deviations between the pre- and post-contingency conditions were recorded whenever these deviations (decreases) were greater than 5%. Over 900 single contingencies were applied to the previously-described pre- and post-project cases, and the results were compared. Simulated outages were predominantly (though not explicitly limited to) N-1 outages of transmission lines 4, transformers, or generators connected at voltages 69kV in Area 14 (Arizona). 3.2 Short-Circuit Duty Short-circuit duty evaluations are conducted by the APS Protection Department using the Computer Aided Protection Engineering ( CAPE ) application. Typically, short-circuit duty analysis simulates both single-phase and three-phase faults at specified busses; the applied methodology assumes a 1.05 prefault voltage, considers X/R ratio, and assesses the correct multiplier to the fault. The interrupting currents are measured at each breaker location and compared for the pre-project and post-project scenarios. Circuit breakers exposed to fault currents in excess of 100 percent of their interrupting capabilities will be replaced or upgraded, whichever is appropriate. 4 Simulated transmission line contingencies outside of Area 14 included N-1 outages of the Palo Verde-Devers, Harquahala Jct.- Devers, Hassayampa-North Gila, North Gila-Imperial Valley, and Imperial Valley-Miguel 500kV lines. Page 17

19 Q54 FeS June 18, 2009 Appendix A CONTINGENCY LIST

20 APPENDIX A CONTINGENCY LIST Q54 FeS June 18, 2009 List of Applied Contingencies: 0 N-0 BASECASE (All Lines in Svc.) 1 N.GILA-IMPERIAL VALLEY 500kV Line 1 (no SPS) 2 N.GILA-IMPERIAL VALLEY 500kV Line 1 (incl. SPS) 3 IMPERIAL VALLEY-MIGUEL 500kV Line 1 (no SPS) 4 IMPERIAL VALLEY-MIGUEL 500kV Line (incl. SPS) 5 PALO VERDE-DEVERS 500kV Line 1 6 HARQJNCT-DEVERS 500kV Line 1 7 DEVERS(LA)-HESPERIA 500kV Line 1 8 MOHAVE-ELDORADO 500kV Line 1 9 CRYSTAL-MCCULLOUGH 500kV Line 1 10 BROWNING-SILVERKG 500kV Line 1 11 CHOLLA-SAGUARO 500kV Line 1 12 CORONADO-SECNOL 500kV Line 1 13 CORONADO-SILVERKG 500kV Line 1 (no SPS) 14 CORONADO-SILVERKG 500kV Line 1 (incl. SPS) 15 DINOSAUR-BROWNING 500kV Line 1 16 DRPP-FCW 500kV Line 1 17 DRPP-FCW 500kV Line 2 18 FOURCORN-FCW 500kV Line 1 19 FOURCORN-MOENKOPI 500kV Line 1 20 HARQJNCT-HARQUAHA 500kV Line 1 21 HARQJNCT-SNVLY 500kV Line 1 22 HASSYAMP-ARLINTON 500kV Line 1 23 HASSYAMP-HARQJNCT 500kV Line 1 24 HASSYAMP-JOJOBA 500kV Line 1 25 HASSYAMP-MESQUITE 500kV Line 1 26 HASSYAMP-N.GILA 500kV Line 1 27 HASSYAMP-PALOVRDE 500kV Line 1 28 HASSYAMP-PALOVRDE 500kV Line 2 29 HASSYAMP-PALOVRDE 500kV Line 3 30 HASSYAMP-PINAL_W 500kV Line 1 31 HASSYAMP-REDHAWK 500kV Line 1 32 HASSYAMP-REDHAWK 500kV Line 2 33 JOJOBA-GILARIVR 500kV Line 1 34 JOJOBA-GILARIVR 500kV Line 2 35 JOJOBA-KYRENE 500kV Line 1 36 KYRENE-BROWNING 500kV Line 1 37 MEAD-MARKETPL 500kV Line 1 38 MEAD-PERKINS 500kV Line 1 39 MOENKOPI-ELDORDO 500kV Line 1 40 MOENKOPI-RME 500kV Line 1 41 MOENKOPI-YAVAPAI 500kV Line 1 42 NAVAJO-CRYSTAL 500kV Line 1 43 NAVAJO-RME 500kV Line 1 44 NAVAJO-VV1 500kV Line 1 45 PALOVRDE-RUDD 500kV Line 1 46 PALOVRDE-WESTWING 500kV Line 1 47 PALOVRDE-WESTWING 500kV Line 2 48 PERK PS2-PERKINPS 500kV Line 1 49 PERKINPS-PERK PS1 500kV Line 1 50 PERKINPS-WESTWING 500kV Line 1 51 PERKINS-PERKINPS 500kV Line 1 52 PINAL_SO-SES 500kV Line 1 53 PINAL_SO-TORTOLIT 500kV Line 1 54 PINAL_W-SNTAROSA 500kV Line 1 55 RACEWAY-PNPKAPS 500kV Line 1 56 RACEWAY-WESTWING 500kV Line 1 57 RME-FCW 500kV Line 1 58 SAGUARO-TORTOLIT 500kV Line 1 59 SAGUARO-TORTOLIT 500kV Line 2 60 SECNOL-CHOLLA 500kV Line 1 61 SES-DINOSAUR 500kV Line 1 62 SNTAROSA-PINAL_SO 500kV Line 1 63 VV1-RACEWAY 500kV Line 1 64 YAVAPAI-WESTWING 500kV Line 1 65 BICKNELL-VAIL 345kV Line 1 66 CHOLLA-PNPKAPS 345kV Line 1 67 CHOLLA-PRECHCYN 345kV Line 1 68 FLAGSTAF-GLENCANY 345kV Line 1 69 FLAGSTAF-GLENCANY 345kV Line 2 70 FLAGSTAF-PINPKBRB 345kV Line 1 71 FLAGSTAF-PINPKBRB 345kV Line 2 72 FOURCORN-CHOLLA 345kV Line 1 73 FOURCORN-CHOLLA 345kV Line 2 74 FOURCORN-SAN_JUAN 345kV Line 1 75 GREENLEE-COPPERVR 345kV Line 1 76 GREENLEE-WILLOW 345kV Line 1 77 GREENLEE-WINCHSTR 345kV Line 1 78 GREEN-SW-GREENLEE 345kV Line 1 79 LIBERTY-PEACOCK 345kV Line 1 80 MAZATZAL-PNPKAPS 345kV Line 1 81 MCKINLEY-SPRINGR 345kV Line 1 82 MCKINLEY-SPRINGR 345kV Line 2 83 PEACOCK-MEAD 345kV Line 1 84 PINALWES-SOUTH 345kV Line 1 85 PRECHCYN-MAZATZAL 345kV Line 1 86 SAN_JUAN-MCKINLEY 345kV Line 1 87 SAN_JUAN-MCKINLEY 345kV Line 2 88 SHIPROCK-FOURCORN 345kV Line 1 89 SOUTH-GATEWAY 345kV Line 1 90 SOUTH-GATEWAY 345kV Line 2 91 SPRINGR-CORONADO 345kV Line 1 92 SPRINGR-GREENLEE 345kV Line 1 93 SPRINGR-VAIL2 345kV Line 1 94 VAIL-SOUTH 345kV Line 1 95 WESTWING-PINALWES 345kV Line 1 96 WILLOW-BOWIE 345kV Line 1 97 WILLOW-BOWIE 345kV Line 2 98 WINCHSTR-VAIL 345kV Line 1 99 WINCHSTR-WILLOW 345kV Line AGUAFRIA-ALEXANDR 230kV Line AGUAFRIA-WESTWNGW 230kV Line AGUAFRIA-WHITETNK 230kV Line ANDERSON-KYR-NEW 230kV Line APACHE-BUTERFLD 230kV Line APACHE-RED TAIL 230kV Line APACHE-WINCHSTR 230kV Line AVERY-RACEWAY 230kV Line AVERY-TS6 230kV Line BRANDOW-KYRENE 230kV Line BRANDOW-PAPAGOBT 230kV Line BRANDOW-WARD 230kV Line BRANDOW-WARD 230kV Line BROWNING-DINOSAUR 230kV Line BROWNING-SANTAN 230kV Line BUCKEYE-LIBERTY 230kV Line 1 (incl. closing Buckeye backtie.) 116 BUCKEYTP-LIBERTY 230kV Line BUTERFLD-SAN RAF 230kV Line BUTERFLD-SLOAN 230kV Line CACTUS-OCOTILLO 230kV Line CHOLLA-LEUPP 230kV Line COOLIDGE-SUN ARIZ 230kV Line COOLIDGE-SUN ARIZ 230kV Line COPPERVR-FRISCO 230kV Line CORBELL-KYRENE 230kV Line CTRYCLUB-GRNDTRML 230kV Line CTRYCLUB-LINCSTRT 230kV Line CTRYCLUB-MEADOWBK 230kV Line DAVIS-MCCULLGH 230kV Line DAVIS-MEAD N 230kV Line DAVIS-RIVIERA 230kV Line DAVIS-TOPOCK 230kV Line DAVIS-ZORB 230kV Line DBG-CASGRAPS 230kV Line DBG-PINAL_S 230kV Line DEERVALY-ALEXANDR 230kV Line DEERVALY-PINPKSRP 230kV Line DEERVALY-WESTWNGE 230kV Line DOSCONDO-HACKBERY 230kV Line EAGLEYE-BUCKEYTP 230kV Line EL SOL-AGUAFRIA 230kV Line EL F-WHTNKAPS 230kV Line FORTROCK-JUNIPRMT 230kV Line FORTROCK-ROUNDVLY 230kV Line FOURCORN-PILLAR 230kV Line GAVILNPK-GAVILNWA 230kV Line GILA-NGL-E 230kV Line GILA-NGL-W 230kV Line GILARIVR-GILABEND 230kV Line GILARIVR-GILABEND 230kV Line 1 (open Gillespi 69kV) 150 GLEN PS-NAVAJO 230kV Line 1 (opens Glen Canyon PS) 151 GLENDALE-GLENDALW 230kV Line GLENDALE-GRNDTRML 230kV Line GLENDALW-AGUAFRIA 230kV Line GOLDFELD-SILVERKG 230kV Line GOLDFELD-THUNDRST 230kV Line GOLDFELD-THUNDRST 230kV Line GRIFFITH-PEACOCK 230kV Line HACKBERY-MORENCI 230kV Line LIBERTY-HASS.-HARCUVAR 230kV Line 160 HILLTOP-MCCONICO 230kV Line HOVRA1A2-MEAD S 230kV Line HOVRA5A6-MEAD S 230kV Line HOVRA7-9-MEAD S 230kV Line HOVRN1N2-MEAD S 230kV Line HOVRN3N4-MEAD S 230kV Line HOVRN5N6-MEAD S 230kV Line HOVRN7N8-MEAD S 230kV Line JOJOBA-GILARIVR 230kV Line JOJOBA-TS4-LIB/PALMVLY 230kV Ckt. 170 JUNIPRMT-SELIGMAN 230kV Line KAYENTA-LNGHOUSE 230kV Line KAYENTA-SHIPROCK 230kV Line KYRENE-SCHRADER 230kV Line KYR-NEW-KNOX 230kV Line KYR-NEW-OCOTILLO 230kV Line LEUPP-COCONINO 230kV Line LIBERTY-PHXWAPA 230kV Line LIBERTY-RUDD 230kV Line LIBERTY-WESTWNGW 230kV Line LIBTYPHS-LIBERTY 230kV Line LINCSTRT-WPHXAPSN 230kV Line LONE BUT-LIBERTY 230kV Line LONE BUT-SUN ARIZ 230kV Line LONE BUT-TESTTRAK 230kV Line LONEPEAK-SUNYSLOP 230kV Line MCCONICO-DAVIS 230kV Line MCCONICO-GRIFFITH 230kV Line MEAD N-HVRA3A4 230kV Line MEAD S-MEAD N 230kV Line MEAD S-MEAD N 230kV Line MEADOWBK-SUNYSLOP 230kV Line 1 A-2

21 APPENDIX A CONTINGENCY LIST Q54 FeS June 18, MILLIGAN-CASGRAPS 230kV Line MORENCI-GREEN-SW 230kV Line MORENCI-PD-MORNC 230kV Line N.WADDEL-RACEWAY 230kV Line NAVAJO-LNGHOUSE 230kV Line OCOTILLO-LINCSTRT 230kV Line OCOTILLO-PNPKAPS 230kV Line ORME-ANDERSON 230kV Line ORME-ANDERSON 230kV Line ORME-RUDD 230kV Line ORME-RUDD 230kV Line PANTANO-SAHUARIT 230kV Line PAPAGOBT-KYR-NEW 230kV Line PAPAGOBT-PINPKSRP 230kV Line PARKER-BLK MESA 230kV Line PARKER-EAGLEYE 230kV Line PARKER-GENE 230kV Line PARKER-HARCUVAR 230kV Line PARKER-HAVASU 230kV Line PARKER-N.HAVASU 230kV Line PD-MORNC-FRISCO 230kV Line PEACOCK-HILLTOP 230kV Line PHXWAPA-LONE BUT 230kV Line PINPK-GAVILNWA 230kV Line PINPK-PINPKSRP 230kV Line PINPK-PINPKSRP 230kV Line PINPKSRP-BRANDOW 230kV Line PINPKSRP-BRANDOW 230kV Line PNPKAPS-CACTUS 230kV Line PNPKAPS-LONEPEAK 230kV Line PNPKAPS-PINPK 230kV Line PNPKAPS-PINPK 230kV Line PNPKAPS-PINPKSRP 230kV Line PNPKAPS-PINPKSRP 230kV Line PNPKAPS-REACH 230kV Line PRSCOTWA-GAVILNWA 230kV Line PRSCOTWA-PRESCOTT 230kV Line RACEWAY-WESTWNGE 230kV Line REACH-LONEPEAK 230kV Line RED TAIL-DOSCONDO 230kV Line PRSCTWA-RDVLY-PEACOCK 230kV Ckt. 233 ROGERS-THUNDRST 230kV Line ROGERSWA-PINPK 230kV Line ROGERSWA-PINPK 230kV Line ROGERSWA-ROGERS 230kV Line ROGERSWA-ROGERS 230kV Line ROGERSWA-SPOOKHIL 230kV Line RUDD-PLMVLY 230kV Line RUDD-WHITETNK 230kV Line RUDD-WPHXAPSS 230kV Line SAGUARO-MILLIGAN 230kV Line SAGUARO-TATMOMLI 230kV Line SAHUARIT-BICKNELL 230kV Line SANTAN-CORBELL 230kV Line SANTAN-THUNDRST 230kV Line SCHRADER-SANTAN 230kV Line SEV-DINOSAUR 230kV Line SLOAN-PANTANO 230kV Line SLRC-GILA 230kV Line SLRC-GILA 230kV Line SNTAROSA-DBG 230kV Line SNTAROSA-KNOX 230kV Line SNTAROSA-TATMOMLI 230kV Line SNTAROSA-TESTTRAK 230kV Line SNVLY-HASSYAMP 230kV Line SNVLY-TS1 230kV Line SPOOKHIL-COOLIDGE 230kV Line SUN ARIZ-PINAL_S 230kV Line SURPRISE-EL SOL 230kV Line SURPRISE-WESTWNGW 230kV Line TESTTRAK-CASAGRND 230kV Line TOPOCK-BLK MESA 230kV Line TOPOCK-N.HAVASU 230kV Line TOPOCK-SOPOINT 230kV Line TOPOCK-SOPOINT 230kV Line TS1-TS2 230kV Line TS2-PLMVLY 230kV Line TS6-PNPKAPS 230kV Line VERDE S-COCONINO 230kV Line VERDE S-VERDE N 230kV Line WESTWNGW-PINPK 230kV Line WHTNKAPS-RUDD 230kV Line WILOWLKE-WILOWLKW 230kV Line WILOWLKE-YAVAPAI 230kV Line WILOWLKW-PRESCOTT 230kV Line WPHXAPSN-WHTNKAPS 230kV Line YAVAPAI-VERDE N 230kV Line ZORB-TOPOCK 230kV Line PILOTKNB-YUCCA 161kV Line KNOB-PILOTKNB 161kV Line BLYTHE-BLYTHEAZ 161kV Line BLYTHE-BUCKBLVD 161kV Line BLYTHE-GOLDMNTP-KNOB 161kV Line 285 BLYTHE-HEADGATE 161kV Line BOUSE-BLACK PK 161kV Line BOUSE-KOFA 161kV Line GILA-DOME TAP 161kV Line GILA-KNOB 161kV Line KNOB-DESALTER 161kV Line KOFA-DOME TAP 161kV Line PARKER-BLYTHE 161kV Line PARKER-BOUSE 161kV Line PARKER-HEADGATE 161kV Line WLTNMOHK-DOME TAP 161kV Line WLTNMOHK-GILA 161kV Line CRYCROFT-NE.LOOP 138kV Line DELCERRO-WESTINA 138kV Line DMP-N. LOOP 138kV Line DMP-NE.LOOP 138kV Line DMP-SN.CRUZ 138kV Line DMP-TUCSON 138kV Line DREXEL-IRVNGTN 138kV Line DREXEL-MIDVALE 138kV Line E. LOOP-NE.LOOP 138kV Line E. LOOP-PANTANO 138kV Line E. LOOP-ROBERTS 138kV Line GREENVLY-CANOARCH 138kV Line IRVNGTN-KINO 138kV Line IRVNGTN-RBWILMOT 138kV Line IRVNGTN-SOUTH 138kV Line IRVNGTN-VAIL 138kV Line LOSREALS-VAIL 138kV Line N. LOOP-MARANA 138kV Line N. LOOP-RILLITO 138kV Line N. LOOP-WESTINA 138kV Line NARANJA-N. LOOP 138kV Line NE.LOOP-NELP_SVC 138kV Line NE.LOOP-RILLITO 138kV Line PANTANO-LOSREALS 138kV Line RANVISTO-CATALINA 138kV Line RANVISTO-LACANADA 138kV Line RANVISTO-NARANJA 138kV Line RBWILMOT-VAIL 138kV Line RILLITO-LACANADA 138kV Line S.TRAIL-ROBERTS 138kV Line SN.CRUZ-IRVNGTN 138kV Line SNYDER-CRYCROFT 138kV Line SNYDER-E. LOOP 138kV Line SOUTH-ASARCO 138kV Line SOUTH-CYPRUS 138kV Line SOUTH-GREENVLY 138kV Line SOUTH-MIDVALE 138kV Line TORTOLIT-MARANA 138kV Line TORTOLIT-N. LOOP 138kV Line TORTOLIT-N. LOOP 138kV Line TORTOLIT-N. LOOP 138kV Line TUCSON-DELCERRO 138kV Line TUCSON-KINO 138kV Line TWNTYSEC-E. LOOP 138kV Line TWNTYSEC-IRVNGTN 138kV Line VAIL-CIENEGA 138kV Line VAIL-FT.HUACH 138kV Line VAIL-FT.HUACH 138kV Line VAIL-S.TRAIL 138kV Line E5.1N-MRMNFLAT 115kV Line E5.1N-STEWMTN1 115kV Line E2.7N-843E2.7N 115kV Line ADAMS-APACHE 115kV Line ADAMS-PANTANO 115kV Line ANIMAS-MESA FM 115kV Line ANIMAS-SULLIVAN 115kV Line APACHE-SNMANUEL 115kV Line APACHE-SNMANUEL 115kV Line APACHE-SNMANUEL 115kV Line ASARCOSR-ASARCOTP 115kV Line ASARCOTP-CRUSHER 115kV Line ASARCOTP-HAYDENAZ 115kV Line AVRA-MARANA 115kV Line AVRA-SNDARIO 115kV Line BAGCAP-BAGDAD 115kV Line BERGIN-FOOTHILS 115kV Line BERGIN-SAN JUAN 115kV Line BICKNELL-MILLSITE 115kV Line BICKNELL-OXIDEPLT 115kV Line BICKNELL-THREEPNT 115kV Line BONNEYTP-BONNYBRK 115kV Line BONNEYTP-COOLIDGE 115kV Line BONNEYTP-CRUSHER 115kV Line BOOTHILL-ADAMS 115kV Line BOOTHILL-MURAL 115kV Line BRADY-PICACHOW 115kV Line CANEZ-SONOITA 115kV Line CARLOTA-PINTOVLY 115kV Line CARLOTA-SILVERK2 115kV Line CARREL-GOLDFELD 115kV Line CARREL-SPURLOCK 115kV Line COOLIDGE-COL-SCIP 115kV Line COOLIDGE-ED-2 115kV Line COOLIDGE-SIGNAL 115kV Line COOLIDGE-VLYFARMS 115kV Line DEL BAC-NOGALES 115kV Line ED-2-BRADY 115kV Line ED-2-ED-4 115kV Line ED-2-SIGNAL 115kV Line ED-4-ED-5 115kV Line ED-4-ELOY 115kV Line ED-5B-EMPIRE 115kV Line ELLISON-843E2.7N 115kV Line EMPIRE-CASAGRND 115kV Line FOOTHILS-HOODMESA 115kV Line FRAZIER-HORSMESA 115kV Line FRAZIER-MOONSHIN 115kV Line FRAZIER-ROOSEVLT 115kV Line FRUITAP-FRUITLND 115kV Line FRUITAP-HOODMESA 115kV Line GALLEGOS-BERGIN 115kV Line GATEWAY-VALNCIA 115kV Line GLADETAP-HOODMESA 115kV Line GLADETAP-LAPLATA 115kV Line GOLDFELD-461E5.1N 115kV Line 1 A-3

22 APPENDIX A CONTINGENCY LIST Q54 FeS June 18, GOLDFELD-HORSMESA 115kV Line HAYDENAZ-KEARNYTP 115kV Line HOODMESA-SULLIVAN 115kV Line HORSMESA-MRMNFLAT 115kV Line KANTOR-CANEZ 115kV Line KEARNY-KEARNYTP 115kV Line KEARNYTP-MORRISAZ 115kV Line KNOLL-MORRISAZ 115kV Line MARANATP-MARANA 115kV Line MARANATP-RATTLSNK 115kV Line MIAMI-MIAMI 3 115kV Line MIAMI-PINTOVLY 115kV Line MIAMI 3-MIAMI 4 115kV Line MIAMI 3-PINAL 115kV Line MIAMI 4-843E2.7N 115kV Line MOONSHIN-842E2.7N 115kV Line MOONSHIN-PINAL 115kV Line NAVAJO-SAN JUAN 115kV Line NAVISKA-THRNYDLE 115kV Line NOGALES-KANTOR 115kV Line OAKFLAT-SILVERT1 115kV Line OAKFLAT-TRASK 115kV Line ORACLE-S.BRKRCH 115kV Line OXIDEPLT-MILLSITE 115kV Line PANTANO-KARTCHNR 115kV Line PANTANO-NOGALES 115kV Line PICACHOW-RED ROCK 115kV Line PINAL-SILVERT1 115kV Line PRESCOTT-BAGCAP 115kV Line RATTLSNK-TUCSON 115kV Line RATTLSNK-TWINPEAK 115kV Line RAY-SUPERIOR 115kV Line RED ROCK-SAG.EAST 115kV Line REFINERY-842E2.7N 115kV Line S.BRKRCH-SNMANUEL 115kV Line SAG.EAST-MARANATP 115kV Line SAG.EAST-NAVISKA 115kV Line SAG.EAST-ORACLE 115kV Line SAG.EAST-SAG.WEST 115kV Line SAG.WEST-ED-5 115kV Line SAG.WEST-ED-5B 115kV Line SAG.WEST-SNMANUEL 115kV Line SAN JOAQ-BRAWLEY 115kV Line SANXAVER-SAN JOAQ 115kV Line SANXAVER-SNYDHILL 115kV Line SHIPROCK-FRUITAP 115kV Line SHIPROCK-MESA FM 115kV Line SILVERK1-SILVERT1 115kV Line SILVERK2-SUPERIOR 115kV Line SNDARIO-BRAWLEY 115kV Line SNDARIO-SANDARIO 115kV Line SNMANUEL-HAYDENAZ 115kV Line SNMANUEL-HAYDENAZ 115kV Line SNYDHILL-BLACKMTN 115kV Line SONOITA-VALNCIA 115kV Line SPURLOCK-SUPERIOR 115kV Line SUPERIOR-TRASK 115kV Line THREEPNT-SNDARIO 115kV Line THREEPNT-VALEN-SW 115kV Line THRNYDLE-TWINPEAK 115kV Line TUCSON-DEL BAC 115kV Line TUCSON-ORACLE 115kV Line TWINPEAK-SANDARIO 115kV Line VALEN-SW-BLACKMTN 115kV Line VLYFARMS-ORACLE 115kV Line WINSLOW-CHLCONST 69kV Line CHLCONST-CHOLLA2 69kV Line WINSLOW-CHLCONST-CHLA 69kV Ckt 470 CHOLLA1-LEROUX 69kV Line LEROUX-INDWELLS 69kV Line INDWELLS-JEDDITO 69kV Line JEDDITO-KEAMCNYN 69kV Line CHOLLA-LEROUX-INDWELLS-JEDDITO- KEAMCNYN 69kV Ckt 475 LINDEN-SHOW LOW 69kV Line SHOW LOW-SHUMWAY 69kV Line SHOW LOW-SHUMWAY 69kV Line (close Vernon tie) 478 SHUMWAY-SNOWFLAK 69kV Line SHUMWAY-SNOWFLAK 69kV Line (close Vernon tie) 480 LEROUX-LEROUXTP 69kV Line (normally open) 481 CHOLLA2-LEROUXTP 69kV Line LEROUXTP-WOODRUFF 69kV Line WOODRUFF-BACON 69kV Line BACON-SNOWFLAK 69kV Line SNOWFLAK-SECNOL 69kV Line SNOWFLAK-SECNOL 69kV Line (add Shumway shunt) 487 CHOLLA2-WOODRUFF-BACON- SNOWFLAK-SECNOL 69kV Ckt 488 SHOW LOW-VERNONX 69kV Line (normally open) 489 SHOW LOW-PEAPS 69kV Line LINDEN-HEBERTP 69kV Line LINDEN-HEBERTP 69kV Line (close Vernon tie) 492 HEBER-HEBERTP 69kV Line 493 HEBERTP-ZENIFF 69kV Line HEBERTP-ZENIFF 69kV Line (close Vernon tie + caps) 495 LINDEN-HEBER-ZENIFF 69kV Ckt 496 LINDEN-HEBER-ZENIFF 69kV Ckt (close Vernon tie + caps) 497 SECNOL-ZENIFF 69kV Line 498 ABITIBTP-CHOLLA1 69kV Line 499 ABITIBTP-ZENIFF 69kV Line CHOLLA1-ABITIBTP-ZENIFF 69kV Ckt 501 WINSLOW-WINSLOWB 69kV Line WINSLOW-LEUPPJCT 69kV Line SUNSHINE-LEUPPJCT 69kV Line SUNSHINE-PADRE 69kV Line WINSLOW-LEUPPJCT-SUNSHINE- PADRE-FLAGSTAF 69kV Ckt 506 ABITIBTP 69/13.8kV Xfmr SUNSHINE 69/12.5kV Xfmr LEUPPJCT 69/20.8kV Xfmr KEAMCNYN 69/20.8kV Xfmr SHUMWAY 69/12.5kV Xfmr SNOWFLAK 69/12.5kV Xfmr SNOWFLAK 69/12.5kV Xfmr WINSLOW 69/12.5kV Xfmr WINSLOW 69/12.5kV Xfmr LEROUX 69/12.5kV Xfmr WOODRUFF 69/20.8kV Xfmr BACON 69/12.5kV Xfmr SHOW LOW 69/12.5kV Xfmr SHOW LOW 69/12.5kV Xfmr COCONINO-WINONA 69kV Line 521 ELDEN N-SANDVIG 69kV Line 522 ELDEN N-SANDVIG 69kV Line (w/tuba City shunt) 523 SWITZER-SANDVIG 69kV Line 524 COCONINO-SWITZER 69kV Line 525 COCONINO-SWITZER 69kV Line (w/tuba City shunt) 526 COCONINO-VM1 69kV Line 527 COCONINO-VM1 69kV Line (w/capital Butte shunts) 528 VM1-KACHVILL 69kV Line 529 VM1-KACHVILL 69kV Line (w/capital Butte shunts) 530 KACHVILL-MUNDPKTP 69kV Line 531 MUNDPKTP-MUNDPARK 69kV Line 532 MUNDPKTP-SEDONA 69kV Line 533 PRECHCYN-P1 69kV Line 534 PRECHCYN-P1 69kV Line (w/ load shed) 535 P1-TONTO 69kV Line 536 P1-TONTO 69kV Line (w/ load shed) 537 MAZATZAL-TONTO 69kV Line 538 TONTO-STRAWBTP 69kV Line 539 STRAWBTP-STRAWBRY 69kV Line 540 STRAWBTP-IRVING 69kV Line 541 CHOLLA 500/345kV Xfmr CHOLLA 500/345kV Xfmr CORONADO 500/345kV Xfmr CORONADO 500/345kV Xfmr FOURCORN 500/345kV Xfmr PINAL_W 500/345kV Xfmr WESTWING 500/345kV Xfmr BROWNING 500/230kV Xfmr BROWNING 500/230kV Xfmr GILARIVR 500/230kV Xfmr KYRENE 500/230kV Xfmr KYRENE 500/230kV Xfmr KYRENE 500/230kV Xfmr MEAD 500/230kV Xfmr MEAD 500/230kV Xfmr MESQUITE 500/230kV Xfmr NGL-E 500/230kV Xfmr NGL-W 500/230kV Xfmr PINAL_SO 500/230kV Xfmr PNPKAPS 500/230kV Xfmr PNPKAPS 500/230kV Xfmr PNPKAPS 500/230kV Xfmr RACEWAY 500/230kV Xfmr RACEWAY 500/230kV Xfmr RUDD 500/230kV Xfmr RUDD 500/230kV Xfmr RUDD 500/230kV Xfmr RUDD 500/230kV Xfmr SES 500/230kV Xfmr SILVERKG 500/230kV Xfmr SNVLY 500/230kV Xfmr WESTWING 500/230kV Xfmr WESTWING 500/230kV Xfmr WESTWING 500/230kV Xfmr YAVAPAI 500/230kV Xfmr YAVAPAI 500/230kV Xfmr TORTOLIT 500/138kV Xfmr TORTOLIT 500/138kV Xfmr SAGUARO 500/115kV Xfmr SAGUARO 500/115kV Xfmr CORONADO 500/69kV Xfmr N.GILA 500/69kV Xfmr N.GILA 500/69kV Xfmr SECNOL 500/69kV Xfmr SECNOL 500/69kV Xfmr (close Vernon tie + caps) 586 VV1 500/69kV Xfmr BICKNELL 345/230kV Xfmr CHOLLA 345/230kV Xfmr COPPERVR 345/230kV Xfmr FOURCORN 345/230kV Xfmr FOURCORN 345/230kV Xfmr GLENCANY 345/230kV Xfmr GLENCANY 345/230kV Xfmr GREEN-SW 345/230kV Xfmr GREEN-SW 345/230kV Xfmr 2 A-4

23 APPENDIX A CONTINGENCY LIST Q54 FeS June 18, LIBERTY 345/230kV Xfmr MEAD 345/230kV Xfmr PEACOCK 345/230kV Xfmr PINPKBRB 345/230kV Xfmr PINPKBRB 345/230kV Xfmr PINPKBRB 345/230kV Xfmr PNPKAPS 345/230kV Xfmr PNPKAPS 345/230kV Xfmr PNPKAPS 345/230kV Xfmr SHIPROCK 345/230kV Xfmr WINCHSTR 345/230kV Xfmr SOUTH 345/138kV Xfmr SOUTH 345/138kV Xfmr VAIL 345/138kV Xfmr VAIL2 345/138kV Xfmr GATEWAY 345/115kV Xfmr CHOLLA 345/69kV Xfmr FLAGSTAF 345/69kV Xfmr MAZATZAL 345/69kV Xfmr PRECHCYN 345/69kV Xfmr PRECHCYN 345/69kV Xfmr GLEN PS 230/230kV Xfmr SHIP PS 230/230kV Xfmr GILA 230/161kV Xfmr PARKER 230/161kV Xfmr PARKER 230/161kV Xfmr APACHE 230/115kV Xfmr APACHE 230/115kV Xfmr BICKNELL 230/115kV Xfmr BICKNELL 230/115kV Xfmr CASAGRND 230/115kV Xfmr COOLIDGE 230/115kV Xfmr COOLIDGE 230/115kV Xfmr GOLDFELD 230/115kV Xfmr GOLDFELD 230/115kV Xfmr HARCUVAR 230/115kV Xfmr PANTANO 230/115kV Xfmr PRESCOTT 230/115kV Xfmr PRESCOTT 230/115kV Xfmr SAGUARO 230/115kV Xfmr SAGUARO 230/115kV Xfmr SHIPROCK 230/115kV Xfmr SILVERKG 230/115kV Xfmr SILVERKG 230/115kV Xfmr SNTAROSA 230/115kV Xfmr AF-NORTH 230/69kV Xfmr AF-NORTH 230/69kV Xfmr AGUAFRIA 230/69kV Xfmr ALEXANDR 230/69kV Xfmr ALEXANDR 230/69kV Xfmr ALEXANDR 230/69kV Xfmr ANDERSRS 230/69kV Xfmr ANDERSRS 230/69kV Xfmr ANDERSRS 230/69kV Xfmr ANDERSRS 230/69kV Xfmr BLKMESA1 230/69kV Xfmr BLKMESA2 230/69kV Xfmr BLKMSA34 230/69kV Xfmr BLKMSA34 230/69kV Xfmr BRANDOW 230/69kV Xfmr BRANDOW 230/69kV Xfmr BRANDOW 230/69kV Xfmr BROWNING 230/69kV Xfmr BUCKEYE 230/69kV Xfmr BUCKEYE 230/69kV Xfmr CACTUS 230/69kV Xfmr CACTUS 230/69kV Xfmr CACTUS 230/69kV Xfmr CASGRAPS 230/69kV Xfmr CHOLLA 230/69kV Xfmr CHOLLA 230/69kV Xfmr COCONINO 230/69kV Xfmr COCONINO 230/69kV Xfmr CORBELRS 230/69kV Xfmr CORBELRS 230/69kV Xfmr CORBELRS 230/69kV Xfmr CTRYCLUB 230/69kV Xfmr CTRYCLUB 230/69kV Xfmr DAVIS 230/69kV Xfmr DEERVALY 230/69kV Xfmr DEERVALY 230/69kV Xfmr DEERVALY 230/69kV Xfmr DINOSAUR 230/69kV Xfmr DOSCONDO 230/69kV Xfmr DOSCONDO 230/69kV Xfmr EAGLEYE 230/69kV Xfmr EAGLEYE 230/69kV Xfmr EL SOL 230/69kV Xfmr EL SOL 230/69kV Xfmr FOURCORN 230/69kV Xfmr GAVILNPK 230/69kV Xfmr GILABEND 230/69kV Xfmr GILABEND 230/69kV Xfmr GRIFFITH 230/69kV Xfmr HACKBERY 230/69kV Xfmr HACKBERY 230/69kV Xfmr HILLTOP1 230/69kV Xfmr HILLTOP2 230/69kV Xfmr JOJOBA 230/69kV Xfmr KNOX 230/69kV Xfmr KYRENEGT 230/69kV Xfmr KYRENEGT 230/69kV Xfmr KYRENEGT 230/69kV Xfmr LINCSTRT 230/69kV Xfmr LONE BUT 230/69kV Xfmr LONEPEAK 230/69kV Xfmr LONEPEAK 230/69kV Xfmr MEAD S 230/69kV Xfmr MEAD S 230/69kV Xfmr MEADOWBK 230/69kV Xfmr MILLIGAN 230/69kV Xfmr N.HAVASU 230/69kV Xfmr OCOTILLO 230/69kV Xfmr OCOTILLO 230/69kV Xfmr ORME RS 230/69kV Xfmr ORME RS 230/69kV Xfmr ORME RS 230/69kV Xfmr ORME RS 230/69kV Xfmr PAPAGOBT 230/69kV Xfmr PAPAGOBT 230/69kV Xfmr PAPAGOBT 230/69kV Xfmr PAPAGOBT 230/69kV Xfmr PLMVLY 230/69kV Xfmr PNPKAPS 230/69kV Xfmr PNPKAPS 230/69kV Xfmr PNPKAPS 230/69kV Xfmr PNPKAPS 230/69kV Xfmr RACEWAY 230/69kV Xfmr REACH 230/69kV Xfmr REACH 230/69kV Xfmr RED TAIL 230/69kV Xfmr RIVIERA 230/69kV Xfmr RIVIERA 230/69kV Xfmr ROGERS 230/69kV Xfmr ROGERS 230/69kV Xfmr ROUNDVLY 230/69kV Xfmr SAN RAF 230/69kV Xfmr SANTAN 230/69kV Xfmr SANTAN 230/69kV Xfmr SANTAN 230/69kV Xfmr SCHRADER 230/69kV Xfmr SCHRADER 230/69kV Xfmr SCHRADER 230/69kV Xfmr SEV 230/69kV Xfmr SLOAN 230/69kV Xfmr SNTAROSA 230/69kV Xfmr SPOOKHIL 230/69kV Xfmr SPOOKHIL 230/69kV Xfmr SUNYSLOP 230/69kV Xfmr SUNYSLOP 230/69kV Xfmr SURPRISE 230/69kV Xfmr SURPRISE 230/69kV Xfmr SURPRISE 230/69kV Xfmr TESTTRAK 230/69kV Xfmr THUNDRST 230/69kV Xfmr THUNDRST 230/69kV Xfmr THUNDRST 230/69kV Xfmr THUNDRST 230/69kV Xfmr TOPOCK 230/69kV Xfmr TS1 230/69kV Xfmr TS6 230/69kV Xfmr VERDE N 230/69kV Xfmr VERDE S 230/69kV Xfmr WARD RS 230/69kV Xfmr WARD RS 230/69kV Xfmr WESTWNGE 230/69kV Xfmr WESTWNGE 230/69kV Xfmr WHITETNK 230/69kV Xfmr WHITETNK 230/69kV Xfmr WHTNKAPS 230/69kV Xfmr WHTNKAPS 230/69kV Xfmr WILOWLKE 230/69kV Xfmr WILOWLKW 230/69kV Xfmr WPHXAPSS 230/69kV Xfmr WPHXAPSS 230/69kV Xfmr WPHXAPSS 230/69kV Xfmr YAVAPAI 230/69kV Xfmr BLACK PK 161/69kV Xfmr GILA 161/69kV Xfmr GILA 161/69kV Xfmr HEADGATE 161/69kV Xfmr KOFA 161/69kV Xfmr PARKER 161/69kV Xfmr YUCCA W 161/69kV Xfmr YUCCA W 161/69kV Xfmr AGUAFR 1 Unit AGUAFR 2 Unit AGUAFR 3 Unit APACHCT1 Unit APACHCT2 Unit APACHCT3 Unit APACHCT4 Unit APACHST1 Unit APACHST2 Unit APACHST3 Unit ARL-CT1 Unit ARL-CT2 Unit ARL-ST1 Unit BLYENG1 Unit BLYENG2 Unit BLYENG3 Unit CHOLLA Unit CHOLLA2 Unit CHOLLA3 Unit CHOLLA4 Unit CORONAD1 Unit CORONAD2 Unit CROSSHYD Unit DAVISG1 Unit DAVISG2 Unit 1 A-5

24 APPENDIX A CONTINGENCY LIST Q54 FeS June 18, DAVISG3 Unit DAVISG4 Unit DAVISG5 Unit DBG-CT1 Unit DBG-CT2 Unit DBG-ST1 Unit DMPCCT#1 Unit DRPP G1 Unit DRPP G2 Unit FCNGEN 1 Unit FCNGEN 2 Unit FCNGEN 3 Unit FCNGN4CC Unit FCNGN5CC Unit GIL-CT1 Unit GIL-CT2 Unit GIL-CT3 Unit GIL-CT4 Unit GIL-CT5 Unit GIL-CT6 Unit GIL-CT7 Unit GIL-CT8 Unit GIL-ST1 Unit GIL-ST2 Unit GIL-ST3 Unit GIL-ST4 Unit GLENC1-2 Unit GLENC1-2 Unit GLENC3-4 Unit GLENC3-4 Unit GLENC5-6 Unit GLENC5-6 Unit GLENC7-8 Unit GLENC7-8 Unit GRIFFTH1 Unit GRIFFTH2 Unit GRIFFTH3 Unit HEADGAT1 Unit HEADGAT2 Unit HEADGAT3 Unit HGC-CT1 Unit HGC-CT2 Unit HGC-CT3 Unit HGC-ST1 Unit HGC-ST2 Unit HOOVERA3 Unit HOOVERA4 Unit HOOVERA5 Unit HOOVERA6 Unit HOOVERA7 Unit HOVRA1A2 Unit A1 857 HOVRA1A2 Unit A2 858 HOVRA8A9 Unit A8 859 HOVRA8A9 Unit A9 860 HOVRN1N2 Unit N1 861 HOVRN1N2 Unit N2 862 HOVRN3N4 Unit N3 863 HOVRN3N4 Unit N4 864 HOVRN5N6 Unit N5 865 HOVRN5N6 Unit N6 866 HOVRN7N8 Unit N7 867 HOVRN7N8 Unit N8 868 HRSMS123 Unit HRSMS123 Unit HRSMS123 Unit HRSMS4 Unit KYREN 7A Unit KYREN 7S Unit KYRENE 4 Unit KYRENE 5 Unit MES-CT1 Unit MES-CT2 Unit MES-CT3 Unit MES-CT4 Unit MES-ST1 Unit MES-ST2 Unit MRMFLT12 Unit MRMFLT12 Unit N.WADDEL Unit NAVAJO 1 Unit NAVAJO 2 Unit NAVAJO 3 Unit NLOOPCT Unit NLOOPCT Unit NLOOPCT Unit NLOOPCT Unit OCOTGT1 Unit OCOTGT2 Unit OCOTST1 Unit OCOTST2 Unit PALOVRD1 Unit PALOVRD2 Unit PALOVRD3 Unit PARKERG1 Unit PARKERG2 Unit PARKERG3 Unit PARKERG4 Unit RED-CT1 Unit RED-CT2 Unit RED-CT3 Unit RED-CT4 Unit RED-ST1 Unit RED-ST2 Unit RSVLTGEN Unit RVERSIDE Unit SAG. CT1 Unit SAG. CT2 Unit SAG. CT3 Unit SAGUARO1 Unit SAGUARO2 Unit SANTAN 1 Unit SANTAN 2 Unit SANTAN 3 Unit SANTAN 4 Unit SANTN 5A Unit SANTN 5B Unit SANTN 5S Unit SANTN 6A Unit SANTN 6S Unit SLRC-CT1 Unit SLRC-CT2 Unit SLRC-ST1 Unit SOCONHYD Unit SOPOINT1 Unit SOPOINT2 Unit SOPOINT3 Unit SPR GEN1 Unit SPR GEN2 Unit SPR GEN3 Unit SPR GEN4 Unit STEWMTN Unit SUN G1 Unit SUN G2 Unit SUN G3 Unit SUN G4 Unit SUN G5 Unit SUN G6 Unit SUN G7 Unit SUN G8 Unit SUN G9 Unit SUN G10 Unit SUNDTCT Unit SUNDTCT Unit SUNDTGE1 Unit SUNDTGE2 Unit SUNDTGE3 Unit SUNDTGE4 Unit WPCC4CT1 Unit WPCC4ST1 Unit WPCC5CT1 Unit WPCC5CT2 Unit WPCC5ST1 Unit WPHX CC1 Unit WPHX CC2 Unit WPHX CC3 Unit YUCCACT1 Unit YUCCACT3 Unit YUCCACT4 Unit YUCCAGEN Unit (G-1) Gila River Power Block 1 (470MW) 966 (G-1) Red Hawk Power Block 1 (470MW) 967 (G-1) Arlington-Hass. 500kV Line & Arlington Plant (575MW) 968 (G-1) Harquahala Power Block 1 (550MW) 969 Harq.-Harq. Jct. 500kV Line & Harq. Plant (1100MW) 970 (G-1) Mesquite Power Block (620MW) 971 (G-1) Mesq.-Hass. 500kV Line & Mesquite Plant (1240MW) A-6

25 Q54 FeS June 18, 2009 Appendix B POWER FLOW PLOTS

26 APPENDIX B POWER FLOW PLOTS Q54 FeS June 18, 2009 Case 1: 2012 Pre-Project B-1

27 APPENDIX B POWER FLOW PLOTS Q54 FeS June 18, 2009 Case 2: 2012 Post-Project, Power Scheduled to Palo Verde B-2

28 APPENDIX B POWER FLOW PLOTS Q54 FeS June 18, 2009 Case 3: 2012 Post-Project, Power Scheduled to APS B-3

29 APPENDIX B POWER FLOW PLOTS Q54 FeS June 18, 2009 Case 4: 2012 Post-Project, Power Scheduled to APS B-4