Attachment A Page 1 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN. Prepared for the Arizona Corporation Commission

Transcription

1 Page 1 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN Prepared for the Arizona Corporation Commission January 2012

2 Page 2 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN TABLE OF CONTENTS GENERAL INFORMATION... 1 Changes from Ten-Year Plan... 7 New Projects in the Ten-Year Plan... 8 Conceptual Projects in the Feasibility Planning Phase... 8 PLANNED TRANSMISSION MAPS Arizona EHV and Outer Divisions (see page 11) Phoenix Metropolitan Area (see page 12) Yuma Area (see page 13) PLANNED TRANSMISSION DECRIPTION Youngs Canyon 345/69kV mterconnection at Western's Fiagstaff345kV switchyard Delaney - Palo Verde 500kV * Bagdad 115kV Relocation Project Desert Basin - Pinal Central 230kV Pinal Central- Sundance 230kV Mazatzal loop-in of Cholla - Pinnacle Peak 345kV Delaney - Sun Valley 500kV Sun Valley - Trilby Wash 230kV Palo Verde Hub - North Gila 500kV # North Gila - TS8 230kV Palm Valley - TS2 - Trilby Wash 230kV

3 Page 3 of 149 Morgan - Sun Valley 500kV Scatter Wash loop-in of Pinnacle Peak-Raceway 230kV Saguaro (TS12): Relocate the 23qkV yard and install a 230/69kV sformer Morgan - Sun Valley 230kV Avery loop-in of Pinnacle Peak-Raceway 230kV Mural- San Rafael 230kV Jojoba loop-in of Liberty (TS4)-Panda 230kV TS8 - Yucca 230kV Sun Valley-TSI0-TSl1230kV Buckeye - TSII - Sun Valley 230kV Raceway - Westwing 230kV El Sol- Westwing 230kV Palo Verde - Saguaro 500kV * Projects are included in APS 's response to Decision No (December 11, 2008), Docket No. E-00000D regarding transmission for renewable energy projects and were approved as such in Decision No (January 6, 201l), Docket No. E-01345A-1O See additional information in the Ten-Year smission System Plan related to development plans and in-service dates. -11-

4 Page 4 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN GENERAL INFORMATION Pursuant to A.R.S , Arizona Public Service Company ("APS") submits its Ten-Year smission System Plan ("Ten-Year Plan"). Additionally, pursuant to Arizona Corporation Commission ("Commission") Decision No (July 25,2001) concerning the first Biennial smission Assessment ("BTA"), APS is including with this filing its smission Planning Process and Guidelines and maps showing system ratings on APS's transmission system. The smission Planning Process and Guidelines outline generally APS 's internal planning for its high voltage and extra-high voltage ("EHV") transmission system, including a discussion of APS 's planning methodology, planning assumptions, and its guidelines for system performance. The system ratings maps show continuous and emergency system ratings on APS 's EHV system, and on its Metro, Northern, and Southern 230kV systems. The Ten-Year Plan is conducted and filed annually with the Commission. This Ten-Year Plan describes planned transmission lines of 115kV or higher voltage that APS may construct or participate in over the next ten-year period. Pursuant to A.R.S (10), underground facilities are not included. There are approximately 165 miles of 500kV transmission lines, 98 miles of 230kV transmission lines, 6 miles of 115kV transmission lines, and 5 bulk transformers contained in the projects in this Ten-Year Plan filing. The total investment for the APS projects and the anticipated APS portion of the participation -1-

5 Page 5 of 149 projects as they are modeled in this filing is estimated to be approximately $550 million I. The following table shows a breakdown of the projects contained in this Ten-Year Plan. In addition to the new projects described in this report, the Commission's Sixth BTA (Decision No dated December 10, 2010) recommended that transmission plans should include information regarding planned transmission reconductor projects and substation transformer replacements. Below is a list of transformer replacements and additions. At this time, APS does not have any plans for reconductoring any existing transmission lines. These types of plans often change as they typically are in direct response to load growth or generator interconnections. Therefore, in-service dates for transformer replacement/additions and transmission reconductor projects change to reflect the load changes in the local system. Also, there may be projects added throughout the course of the planning year in-order to accommodate new generator interconnections. 1 The first three years of these additions are included in the Capital Expenditures table presented in the "Liquidity and Capital Resources" section of APS's lo-k filing along with other transmission costs for new sub-transmission projects (69kV) and transmission upgrades and replacements. The Capital Expenditures table shows $577M for 2012 thru

6 Page 6 of 149 Bulk sformer AdditionslReplacements Some of the facilities reported in past Ten-Year plan filings that have been completed, canceled, or deferred beyond the upcoming ten-year period and are not included in this report. The projects at the end of this Ten-Year Plan that have "to be determined" in-service dates are projects that have been identified but that are either still outside of the ten-year planning window or have in-service dates that have not yet been established. They have been included in this filing for informational purposes. A summary of changes from last year's plan is provided below, along with a list of projects that have been added to this year's Ten-Year Plan. Also, a section is included that briefly describes projects still in the feasibility planning phase. For convenience of the reader, APS has included system maps showing the electrical connections and in-service dates for all overhead transmission projects planned by APS for Arizona, the Phoenix Metropolitan Area, and the Yuma area. Written descriptions of each proposed transmission project are provided on subsequent pages in the currently expected chronological order of each project. The line routings shown on the system maps and the descriptions of each transmission line are intended to be general, showing electrical connections and not specific routings, and are subject to revision. Specific routing is recommended by the Arizona Power Plant and smission Siting Committee and ultimately approved by the Commission when issuing a Certificate of Environmental Compatibility and through subsequent -3-

7 Page 7 of Southwest smission Coop, Inc. ("SWTC"), on behalf of other participating utilities, will be submitting the Summary Report and Reference Filing of the Cochise County Technical Study Report as part of its Ten-Year Plan submittal. right-of-way acquisition. Pursuant to A.R.S (C)(7), this filing also includes technical study results for the projects identified. The technical study results show project needs that are generally based on either security ( contingency performance), adequacy (generator interconnection or increasing transfer capability), or both. APS participates in numerous regional planning organizations and in the WestConnect organization. Through membership and participation in these organizations, the needs of multiple entities, and the region as a whole, can be identified and studied. This allows for potentially maximizing the effectiveness and use of new projects. Regional organizations of which APS is a member include the Western Electricity Coordinating Council ("WECC"), the Southwest Area smission Planning ("SWAT"), and WestConnect. The plans included in this filing are the result of these coordinated planning efforts. APS provides an opportunity for other entities to participate in future planned projects. As a participant in the SWAT- Southeastern Arizona smission Study ("SATS") subcommittee, APS worked with other stakeholders in Cochise County to develop a transmission plan that will address the recommendations in the Fifth BTA regarding providing continuity of service (Decision No dated December 11,2008).2 As part of its planning process, APS also evaluates the potential for renewable resource and associated transmission development. In response to the Fourth BTA order (Decision No dated March 22,2007), on August 6, 2008, the Joint Biennial smission Assessment Report on Renewables and Available smission Capability was submitted to the Commission on behalf of APS, Salt River Project, Tucson Electric Power, and Southwest smission Cooperative. That report described the collaborative efforts and analysis that was completed -4-

8 Page 8 of 149 with the Southwest Area smission Sub-Regional Planning Group to address transmission for renewable resources, including an assessment of Available sfer Capacity, a description of locations, and the transmission needed to bring renewable resources to load. In addition, in response to the Fifth BTA order, and in collaboration with SWAT and its subgroups, other utilities, and stakeholders, APS developed plans to identify future renewable transmission projects and proposed funding mechanisms to construct the "top three" renewable transmission projects. APS submitted a Renewable smission Action Plan ("RTAP") report containing its prioritized renewable transmission projects to the Commission on October 30, The projects selected were: 1. Delaney - Palo Verde 500kV; 2. North Gila - Palo Verde 500kV #2; 3A. Palo Verde to Liberty; 3B. Gila Bend to Liberty; and 4. Delaney - Blythe (Arizona Portion of Devers II). On January 6, 2011, the Commission approved APS's RTAP filing under Decision No , Docket No. E-01345A-1O-0033 which allows APS to pursue the development steps indicated in the APS RTAP. The Commission's Sixth BT A ordered that utilities include the effects of distributed generation and energy efficiency programs on future transmission needs. APS's modeled load, located in the Technical Study Report section of this filing, addresses these effects. 3 In APS's recent rate settlement approved in Decision No (dated December 30,2009) the Company agreed to "commence permitting, design, engineering, right of way acquisition, regulatory authorization... and line siting for one or more new transmission lines or upgrades" and "to construct such transmission line(s) or upgrade(s)" once APS obtains all required permitting and authorizations (see Exhibit A, 15.4 of Decision No ). APS intends to pursue the Delaney to Palo Verde 500 kv line to begin complying with this commitment, as described in the Company's January 29, 2010 filing requesting approval ofrtps and their associated action plans. -5-

9 Page 9 of 149 APS believes that the projects identified in this Ten-Year Plan, with their associated in-service dates, will ensure that APS's transmission system meets all applicable reliability criteria. Changes in regulatory requirements, regulatory approvals, or underlying assumptions such as load forecasts, generation or transmission expansions, economic issues, and other utilities' plans, may substantially impact this Ten-Year Plan and could result in changes to anticipated in-service dates or project scopes. Additionally, future federal and regional mandates may impact this Ten-Year Plan specifically and the transmission planning process in general. This Ten-Year Plan is tentative only and, pursuant to A.R.S (F), is subject to change without notice at the discretion of APS. -6-

10 Page 10 of 149 CHANGES FROM TEN-YEAR PLAN The following is a list ofprojects that were changed or removed from APS's January 2011 Ten-Year Plan, along with a brief description of why the change was made. The Ql13 (Cedar Mountain) Loop in of Moenkopi-Yavapai SOOkV line project is not included in the Ten-Year Plan because the project has been placed into service. The Hoodoo Wash Loop-in of Hassayampa-North Gila SOOkV line project is not included in the Ten-Year Plan because the project has been placed into service. The TS12 Saguaro-Milligan loop-in 230/69kV project has changed scope in that the new TS12 Substation will not be built; instead the existing Saguaro 230kV substation will be expanded within the Saguaro property footprint and will include transformation from 230kV to 69kV. The project is now titled "Saguaro (TS12): Relocate the 230kV yard and install a 230/69kV sformer." -7-

11 Page 11 of 149 In-Service Date Changes Saguaro (TS12): Relocate the 230kV yard and install a 230/69kV sformer Scatter Wash loop-in of Pinnacle Peak-Raceway 230kV Delaney-Sun Valley 500kV line Sun Valley-Trilby Wash 230kV line Mazatzal loop in ofcholla-pinnacle Peak 345kV line Palo Verde Hub-North Gila 500kV # North Gila - TS8 230kV The in-service dates shown in this table are based on load projects, not potential interconnections. New generation interconnections may accelerate the in-service date. NEW PROJECTS IN THE TEN-YEAR PLAN There are no new projects planned within the Ten-Year Plan that were not in the Ten-Year Plan. CONCEPTUAL PROJECTS IN THE FEASIBILITY PLANNING PHASE Palo Verde/Gila Bend Area To Valley smission Capacity Additional transmission capacity will be studied from the Palo Verde/Gila Bend areas to the Phoenix load center. This transmission capacity is a robust component of the overall APS transmission and resource need. The areas around and west of Palo Verde as well as the Gila Bend area contain some of the best solar resources in the country. APS expects that at least a -8-

12 Page 12 of 149 portion of the future solar resources specified in the APS resource plan will be developed in relatively close proximity to these areas and will be supported by this transmission capacity. These areas also provide access to existing gas resources and, in the case of Palo Verde, potential new gas resources and market purchases. APS expects to need additional Palo Verde/Gila Bend transmission capacity, beyond what is shown in this plan, to deliver these resources to load and currently expects to require this additional capacity in the timeframe absent a desire for advanced renewable resource development. -9-

13 Page 13 of 149 PLANNED TRANSMISSION MAPS Arizona EHV and Outer Divisions (see page 11) Phoenix Metropolitan Area (see page 12) Yuma Area (see page 13) -10-

14 Page 14 of 149 APS EHV & OUTER DIVISION lev TRANSMISSION PLANS TO CRYSTAL '--I._ NAVAJO FOUR CORNERS._ J N.GILA,,, ", 2015 "... COOLIDGE VALLEY FARMS PINAL CENTRAL 2014 LEGENp EXISTING 500 KV LINES EXISTING 345 KV LINES EXISTING 230 KV LINES EXISTING 115 KV LINES _. PLANNED 500KV LINES PLANNED 230KV LINES o 115KV & ABOVE SUBSTATION (EXISTING) ~ NUCLEAR POWER PLANT 230KV & ABOVE SUBSTATION (FUTURE) Substation locations and line routings depict an electrical connection only and do D21 reflect any assumed physicallocalions or routing. SAGUARO ORACLE JUNCTION ADAMS "':; -11-

15 Page 15 of 149 PHOENIX METROPOLITAN AREA TRANSMISSION PLANS ToNew Waddell '\ ~_~'!'!AN 2016"""-y--,._ ,-~ ---- " Q'(' "..- ~ I / " / TS10 " / 0;;:-TBD,' / ~ ~ I / SUN VALLEY '~ 2015 TRILBY ~ === === _ "'.0 WASH I ~... I :lof"=== :::::(") 2015 To Prescott ~... GAVILAN Care'ree Hwy., PEAK ", " ", If " I '", I,: II - TO i I I TO, PALO VERDE I I \DELANEY a I... ID \.. I ~ I t \ I "'""' BELL RD. II YTS11 I TBD I I I I I l a II!! I I I I II TS2 11 I~ TBD Q CO) ~ ll fii ~ I t PALM II l a SURPRISE I I I!! WHITE TANKS ~ ~ AGUA FRIA 1-10FWY. DEER VALLEY I' Scatter Wash LONE PEAK REACH TO GLEN CANYON ~ ~ TO CHOLLA RUDD Panda,JOINTLY OWNED EXISTING 500KV UNES _ APS EXISTING :w.5kv UNES _ APS ~)(lsting 230KV UNI!S APS PLANNED UNES 230KV 5OO1tV 230KV SUBSTATION (EXISTING. =:"~~NES OWNED BY SRP 230KV SUBSTATION (FUTURE)O 345kY LINES OWNED BY WAPA GENERATING SITE & - I 230KV SUBSTATION _ Subabltlons aoc.tlona and line routing re approximate ~ " TO BROWNING -12-

16 Page 16 of 149 Yuma Area smission Plans yea Hoodoo! OJ C.~ C To Hassayampa Pacific \1 'E ~ ii C),_.. M.O., a_a. Dupont 2015 o,,, TBD a_eel,.., Marine South Air Base Araby, O'Neill " ' ---- I":, <::>" 2012,2012 " '1', 'aldrip: " 0 ~~~---t------~~----~l ~~-----j,' " ",.,' YM1,---- t. o', " " N,...,2! OJ c ~ TS EXISTING 500KV LINES PLANNED 50QKV LINES PLANNED 230KV LINES EXISTING 161KV LINES EXISTING 69KV LINES PLANNED 69KV LINES Substation locations and line routings depict an electrical connection only and do!l.ql reflect any assumed physical locations or routing. TRANSMISSION SUBSTATION NON-APS SUBSTATION DISTRIBUTION SUBSTATION (EXISTING) DISTRIBUTION SUBSTATION (PLANNED) GENERATING SITE & 69KV suest ATtON Street. Highway -D o.l -13-

17 Page 17 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description 2012 Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin Youngs Canyon 345/69kV Interconnection at Western's Fiagstaff345kV switchyard Arizona Public Service Company None 345kV AC 100MVA Western's Flagstaff 345kV switchyard; Sec. 24, T21N, R9E (d) Intermediate Points of Interconnection (e) Point of Termination (f) Length Less than 1 mile Routing Pumose Date (a) Construction Start 2011 (b) Estimated In Service 2012 Permitting I Siting Status A new Youngs Canyon 345/69kV substation to be in-service by 2012; Sec. 24, T21N, R9E A 345/69kV transformer will interconnect into Western's Flagstaff switchyard. This project is needed to provide the electrical source and support to the sub-transmission system in APS's northern service area. The project will provide increased reliability and continuity of service for the communities in northern Arizona. It is not anticipated that a Certificate of Environmental Compatibility will be needed for this project. -14-

18 Page 18 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection Delaney - Palo Verde 500kV * Arizona Public Service Company SRP,CAWCD 500kV AC To be determined Palo Verde Switchyard (e) Point of Termination Future Delaney switching station; approximately Sec. 25, T2N, R8W (f) Routing Purpose Date Length (a) Construction Start 2013 (b) Estimated In Service 2013 Permitting / Siting Status Approximately 15 miles erally leaving the Palo Verde Hub vicinity following the Palo Verde-Devers #1 and the Hassayampa-Harquahala 500kV lines to the Delaney Switchyard site in Sec. 25, T2N, R8W. This project is anticipated to interconnect generation projects at the Delaney switchyard. This line is also one section of a new 500kV path from Palo Verde around the western and northern edges of the Phoenix area and terminating at Pinnacle Peak. This is anticipated to be a joint participation project. APS will serve as the project manager. Certificate of Environmental Compatibility issued 8/17/05 (Case No. 128, Decision No , Palo Verde Hub to TS5500kV smission project). APS, as project manager, holds the CEC. 4 The in-service date of2013 assumes a finn resource development to utilize the project in order to effect a 2013 inservice date. Without such development, the project would go in-service in 2015 with the Delaney-Sun Valley project per approval of the APS Renewable smission Action Plan in Decision No (1/6/11), Docket No. E-01345A-1O

19 Page 19 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Bagdad 115kV Relocation Project Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company None 115kV AC 430A Bagdad Capacitor switchyard; Sec. 10, TI4N, R9W Bagdad Mine substation; Sec. 31, TI5N, R9W (f) Length Approximately 5.5 miles Routing Purpose Date (a) Construction Start 2013 (b) Estimated In Service 2014 Beginning at the existing APS capacitor switchyard and extending in a southwesterly direction for approximately 1.5 miles, then turning in a northwesterly direction approximately 4 miles to the existing Bagdad Mine substation. The project primarily crosses federal BLM lands, private lands (owned by the mine) and a short segment on Arizona State Trust Lands. Freeport McMoRan Inc. has future plans to expand the mine in the location of the existing 115kV transmission line. They have requested that APS move the line in a southerly direction beyond the limits of the planned expansion. Permitting / Siting Status Certificate of Environmental Compatibility issued on (Case No. 143, Decision No , Bagdad 115kV Relocation Project). -16-

20 Page 20 of 149 Designation Project Sponsor Other Participants Size Arizona Public Service Company Ten-Year Plan Planned smission Description 2014 Desert Basin - Pinal Central 230kV Salt River Project (a) Voltage Class 230kV AC Arizona Public Service Company (b) Facility Rating To be determined (c) Point of Origin Desert Basin Power Plant Switchyard; Sec. 13, T6S, RSE (d) (e) (f) Routing Purpose Date (a) (b) Intermediate Points of Interconnection Point of Termination Length Construction Start Estimated In Service Permitting / Siting Status Pinal Central substation to be in-seivice by 2014; Sec. 30, T6S, R8E Approximately 21 miles For approximately 6 miles from the Desert Basin erating Station in Casa Grande near Burris and Korsten Roads generally south and east to a point on the certificated Southeast Valley 500kV line near Cornman and Thornton Roads. At that point the 230kV line will be attached to the 500kV structures for approximately 15 miles to the proposed Pinal Central Substation south of Coolidge, AZ. Remove the Remedial Action Scheme that was previously installed on Desert Basin erating Station; improve reliability of the 230kV system in the region by reducing the loading on existing lines in the area; increase local system capacity; reduce reliance on second party transmission system for delivery of Sundance eration facility; create the first 230kV component of the CATS-HV proposed transmission system for the central Arizona area; and establish the Pinal Central Substation, identified as one of the futlrre injection points of power and energy into the expanding central Pinal County load area, which will help local utilities SeNe local load Authority for the portion of the 230kVline to be attached to the 500kV structures is provided for in the CEC granted in Case No. 126, awarded in 2005 (Decision No (8/25) andno (11/14)), andsubsequently confirmed in Decision No (12/8/06), which approved SRP's compliance filingfor Condition 23 of the CEC. SRP was' granted a CEC for Cas'eNo.132 in 2007 (Decision No (6/6))for the approximately six mile portion of the project not previously permitted from Desert Basin erating Station to the vicinity of Cornman and Thornton Roads south of Cas'a Grande. -17-

21 Page 21 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) (b) (c) (d) (e) (f) Routing Purpose Date (a) (b) Voltage Class Facility Rating Point of Origin Intennediate Points of Interconnection Point oftennination Length Construction Start Estimated In Service Permitting / Siting Status Pinal Central- Sundance 230kV Arizona Public Service Company ED-2 230kVAC 3000 A Sundance substation; Sec. 2, T6S, R 7E Pinal Central substation to be in-service by 2014; Sec. 30, T6S, R8E Approximately 6 miles The project will originate at a new substation on the Sundance property, proceeding west and then south along Cuny Road to the half-section between State Route 287 and Earley Road. The final west to east alignment connecting into the Pinal Central Substation will be located within an ACC-approved corridor and is subject to further design and right-of-way acquisition analysis. This project will serve increasing loads in Pinal County, and throughout the APS system, and will improve reliability and continuity of service for the communities in the area. Also, the project will increase the reliability of Sundance by providing a transmission line in a separate corridor than the existing lines that exit the plant. This project, in conjunction with the Desert Basin-Pinal Central 230kV project, will allow APS to reliably and economically deliver energy from Sundance over APSIs transmission system. The project will be constructed as a 230kV double-circuit capable line, but initially operated as a single-circuit. The in-service date for the second circuit will be evaluated in future planning studies Certificate of Environmental Compatibility issued (Case No. 136, Decision No , Sundance to Pinal South 230kV smission project). Note - the Pinal South substation is now referred to as Pinal Central. -18-

22 Page 22 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin Mazatzal loop-in of Cholla - Pinnacle Peak 345kV Arizona Public Service Company None 345kV AC 100MVA Cholla-Pinnacle Peak 345kV line; near Sec. 3, T8N, RlOE (d) Intermediate Points of Interconnection (e) Point of Termination (f) Length Less than 1 mile Routing Purpose Date (a) Construction Start 2014 (b) Estimated In Service 2015 Mazatzal substation to be in-service by 2015; Sec. 3, T8N, RIOE The Mazatzal 345/69kV substation will be constructed adjacent to the Cholla-Pinnacle Peak 345kV line corridor. This project is needed to provide the electric source and support to the sub-transmission system in the area of Payson and the surrounding communities. Additionally, improved reliability and continuity of service will result for the communities in the Payson area. Permitting I Siting Status Certificate of Environmental Compatibility issued on 5/4/11 (Case No. 160, Decision No , Mazatzal Substation and 345kV Interconnection Project). -19-

23 Page 23 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Delaney - Sun Valley 500kV Arizona Public Service Company SRP, CAWCD 500kV AC To be determined (f) Length Approximately 28 miles Routing Future Delaney switching station; approximately Sec. 25, T2N, R8W Sun Valley substation to be in-service by 2015; Sec. 29, T4N, R4W erally follows the Palo Verde-Devers #1 line until crossing the CAP canal. Then easterly, generally following the north side of the CAP canal to the new Sun Valley substation. Purpose Date (a) Construction Start 2013 (b) Estimated In Service 2015 Permitting / Siting Status This project will serve projected need for electric energy in the area immediately north and west of the Phoenix Metropolitan area. It will increase the import capability to the Phoenix Metropolitan area as well as increase the export/scheduling capability from the Palo Verde area to provide access to both solar and gas resources. The project will also increase the system reliability by providing a new transmission source to help serve the areas in the western portions of the Phoenix Metropolitan area. This is a joint participation project with APS as the project manager. Certificate of Environmental Compatibility issued 8/17/05 (Case No. 128, Decision No , Palo Verde Hub to TS5500kV smission project). APS, as project manager, holds the CEC. -20-

24 Page 24 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Sun Valley - Trilby Wash 230kV Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination (t) Routing Purpose Date Length Arizona Public Service Company None 230kV AC 3000 A (a) Construction Start 2014 (b) Estimated In Service 2015 Permitting / Siting Status Sun Valley substation to be in-service by 2015; Sec. 29, T4N, R4W Trilby Wash substation to be in-service by 2015; Sec. 20, T4N, R2W Approximately 15 miles East from the Sun Valley substation along the CAP canal to approximately 243rd Ave., south to the existing 500kV transmission line corridor, and then east along the corridor to the Trilby Wash substation. This project is required to serve the need for electric energy in the western Phoenix Metropolitan area. Also, the project will provide more capability to import power into the Phoenix Metropolitan area along with improved reliability and continuity of service for communities in the area including El Mirage, Surprise, Youngtown, Buckeye, and unincorporated Maricopa county. The first circuit is scheduled to be in-service for the summer of and the in-service date for the second circuit will be evaluated in future planning studies. Certificate of Environmental Compatibility issued 5/5/05 (Case No. 127, Decision No , West Valley North 230kV smission project). -21-

25 Page 25 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin Palo Verde Hub - North Gila 500kV #2 Arizona Public Service Company SRP, IID, WMIDD 500kV AC To be determined Hassayampa switchyard (d) Intermediate Points of Interconnection (e) Point of Termination (f) Length Routing Purpose Date (a) Construction Start 2013 (b) Estimated In Service 2015 Permitting / Siting Status North Gila substation; Sec. 11, T8S, R22W Approximately 110 miles This line will generally follow the route of the existing Hassayampa - North Gila 500kV #1 line. This project will increase the import capability for the Yuma area and export/scheduling capability from the Palo Verde area to provide access to both solar and gas resources. This is a joint participation project with APS as the project manager. This project will also allow the system to accommodate generation interconnection requests. Certificate of Environmental Compatibility issued (Case No. 135, Decision No , Palo Verde Hub to North Gila 500kV smission project). -22-

26 Page 26 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin North Gila - TS8 230kV Arizona Public Service Company None 230kV AC 3000 A North Gila substation; Sec. 11, T8S, R22W (d) Intermediate Points of Interconnection (e) Point of Termination (f) Length Approximately 13 miles Routing Purpose Date (a) Construction Start 2013 (b) Estimated In Service 2015 TS8 230kV substation to be in-service by 2015; final location to be within Section 16, 20, or 21 of T9S, R22W G&SRB&M The routing for this line has not yet been determined. This project serves the need for electric energy, improved reliability, and continuity of service for the greater Yuma area. This project is expected to be double circuit capable with one circuit in service in 2015 and the second circuit in service at a date to be determined. Permitting / Siting Status Certificate of Environmental Compatibility was approved by the Commission on This project is linked with the Palo Verde to North Gila 500kV #2 project and will likely have the same in-service date. -23-

27 Page 27 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination (f) Length Routing Purpose Date (a) Construction Start (b) Estimated In Service Permitting / Siting Status Palm Valley - TS2 - Trilby Wash 230kV Arizona Public Service Company None 230kV AC 3000 A Palm Valley substation; Sec. 24, T2N, R2W TS2 substation to be in-service by TBD; Sec. 25, T3N, R2W Trilby Wash substation to be in-service by 2015; Sec. 20, T4N, R2W Approximately 12 miles North from the Palm Valley substation, generally following the Loop 303 to Cactus Road, west on Cactus Road to approximately 191 st Avenue, and then north on 191 st Avenue to the Trilby Wash substation. This project will serve the need for electric energy in the western Phoenix Metropolitan area and additional import capability into the greater Phoenix Metropolitan area. The proposed second 230kV source for Trilby Wash provides improved system reliability and continuity of service for communities in the area; such as EI Mirage, Surprise, Youngtown, Goodyear, and Buckeye. The first circuit is scheduled to be in-service for the summer of2015; the in-service date for the second circuit will be evaluated in future planning studies. The in-service date for the TS2 substation is currently outside of the ten year planning horizon and will be continuously evaluated in future planning studies ThePalm Valley-TS2 230kVlineportionwassitedasparto/the West Valley South 230kV smission project and a Certificate o/environmental Compatibility was issued 12/22/03 (Case No. 122, Decision No ). The Trilby Wash-TS2 230kV line portion was sited as part o/the West Valley North 230kV smission project and a Certificate o/environmental Compatibility was issued 5/5/05 (Case No. 127, Decision No ). -24-

28 Page 28 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Morgan - Sun Valley 500kV Arizona Public Service Company SRP,CAWCD 500kV AC To be determined Sun Valley substation to be in-service in 2015; Sec. 29, T4N, R4W Morgan substation; Sec. 33, T6N, RlE (f) Length Approximately 40 miles Routing Purpose Date (a) Construction Start 2013 (b) Estimated In Service 2016 erally the line will head north-northeast out of the Sun Valley substation and then east to the Morgan substation. This project will serve the electric energy needs in the northern Phoenix Metropolitan area. It will increase the import capability to the Phoenix Metropolitan area, as well as increase the export/scheduling capability from the Palo Verde Hub area, which includes both solar and gas resources. The project will also increase the reliability ofthe EHV system by completing a 500kV loop that connects the Palo Verde smission system, the Southern Navajo smission system, and the Southern Four Corners system. Additionally, the project will increase reliability by providing a second 500kV source for the Sun Valley substation and providing support for multiple Category C and D transmission contingencies. This project is anticipated to be 500/230kV double-circuit capable. Permitting / Siting Status Certificate of Environmental Compatibility issued on (Case No. 138, Decision No , TS5-TS kV Project) An application for right-of way on the BLM portion of the project has been submitted and will require NEP A compliance prior to land acquisition and final engineering. -25-

29 Page 29 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) (e) (f) Routing Intermediate Points of Interconnection Point oftennination Length Scatter Wash loop-in of Pinnacle Peak-Raceway 230kV Ariwna Public Service Company None 230kVAC 3000 A Pinnacle Peak-Raceway 230kV line; Sec. 8, T4N, R3E Scatter Wash substation; Sec. 8, T4N, R3E Less than 1 mile The Scatter Wash substation will be located adjacent to the Pinnacle Peak Raceway 230kV line. Purpose This project is needed to provide electric energy in the northern portions of the Phoenix Metropolitan area as well as increase the reliability and continuity of service for these areas. Date (a) Construction Start 2020 (b) Estimated In Service 2021 Permitting / Siting Status Certificate of Environmental Compatibility issued on 6/18/03 (Case No. 120, Decision No , North Valley Project. The Scatter Wash Substation was referred to as TS6 in Case 120). -26-

30 Page 30 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination (f) Routing Length Saguaro (TS12): Relocate the 230kV yard and install a 230/69kV sformer Arizona Public Service Company None 230kV AC 188 MVA Saguaro 230kV Substation; approximately Sec. 14, TI0S, R10E Saguaro 230kV Substation; Sec. 14, TIOS, RlOE N/A N/A Purpose Date (a) Construction Start 2020 (b) Estimated In Service 2021 Permitting I Siting Status Relocate the Saguaro 230kV yard, install a 230/69kV transformer and extend a 69kV line from Saguaro to the proposed SElO (Red Rock) substation. A new 69kV source is needed in the vicinity of the planned SElO (Red Rock) substation in order to serve the proj ected local load. It is not anticipated that a Certificate of Environmental Compatibility will be needed for this project. -27-

31 Page 31 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description Designation Morgan - Sun Valley 230kV Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company None 230kV AC To be determined Sun Valley substation to be in-service by 2014; Sec. 29, T4N, R4W To be determined Morgan substation; Sec. 33, T6N, RIE (f) Length Approximately 40 miles Routing Purpose Date (a) Construction Start (b) Estimated In Service This line will be co-located with the Sun Valley to Morgan 500kV line, which generally heads north-northeast out of the Sun Valley substation and then east to the Morgan substation. This project is needed to provide a transmission source to serve future load that emerges in the currently undeveloped areas south and west of Lake Pleasant. This line will be co-located with the Sun Valley-Morgan 500kV line. Permitting / Siting Status Certificate of Environmental Compatibility issued on (Case No. 138, Decision No , TS5-TS kV Project). -28-

32 Page 32 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation Project Sponsor AveI)' loop-in of Pinnacle Peak-Raceway 230kV Arizona Public Service Company Other Participants None Size (a) Voltage Class 230kV AC (b) Facility Rating 3000 A (c) Point of Origin Pinnacle Peak-Raceway 230kV line; Sec. 8, T4N, R3E (d) Intermediate Points of Interconnection ( e) Point of Termination (t) Length Routing AveI)' substation; Sec. 15, TSN, R2E Less than 1 mile The AveI)' substation will be constructed adjacent to the Pinnacle Peak: Raceway 230kV line at approximately the Dove Valley Rd and 39 th Ave. alignments. Purpose This project is needed to provide electric energy in the northern portions of the Phoenix Metropolitan area as well as increase the reliability and continuity of service for these areas. The need date for this substation is continuously evaluated as the load growth in the area is monitored Date (a) Construction Start TBD (b) Estimated In Service TBD Permitting / Siting Status Certificate of Environmental Compatibility issued on 6/18/03 (Case No. 120, Decision No , North Valley Project). -29-

33 Page 33 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin Mural- San Rafael 230kV Arizona Public Service Company To be determined 230kV AC To be determined Mural substation (d) Intermediate Points of Interconnection (e) Point of Termination San Rafael substation (t) Length To Be Determined Routing Purpose Date (a) Construction Start (b) Estimated In Service Permitting / Siting Status The route for this project has not yet been determined. erally the line will head west-northwest out of the Mural substation and then west to the San Rafael substation. This project was identified in the 2008 Biennial smission Assessment to serve the need for electric energy in the Cochise County area. It will increase the import capability to the Cochise County area, as well as increase the reliability of the local EHV system. To be determined To be determined An application for a Certificate of Environmental Compatibility has not yet been filed. -30-

34 Page 34 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation Jojoba loop-in of Liberty (TS4)-Panda 230kV Project Sponsor Other Participants 'Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company None 230kV AC 188 MVA (f) Length Less than 1 mile Routing Purpose Date (a) Construction Start To be determined (b) Estimated In Service Liberty (TS4)-Panda 230kV line; Sec. 25, T2S, R4W Jojoba substation with an in-service TBD; Sec. 25, T2S, R4W The Jojoba kV substation will be constructed adjacent to the Liberty (TS4)-Panda 230kV line. This project will provide the electrical source and support to the sub-transmission system to serve the need for electric energy for the communities including Buckeye, Goodyear, and Gila Bend. The project will also increase the reliability and continuity of service for those areas. To be determined Permitting 1 Siting Status Certificate of Environmental Compatibility issued 10/16/00 (Case No. 102, Decision No , Gila River smission Project) for the Gila River smission Project which included the interconnection of the 230kV substation. -31-

35 Page 35 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation TS8 - Yucca 230kV Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company None 230kV AC To be determined Yucca substation; Sec. 36, T7S, R24W (f) Length Approximately 19 miles Routing Purpose Date (a) Construction Start (b) Estimated In Service TS8 substation will be in-service in 2015; final location to be within Section 16,20, or 21 oft9s, R22W G&SRB&M The routing for this line has not yet been determined. This double circuit 230kV project will serve the need for electric energy, improve reliability, and continuity of service for the greater Yuma area. Additionally, this project will provide a second electrical source to the future TS8 substation. The ability to transmit electric energy generated by renewable resources in the region may be an additional benefit subject to study by APS in regional planning forums. To be determined To be determined Permitting / Siting Status Certificate of Environmental Compatibility was approved by the Commission on

36 Page 36 of 149 Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Sun Valley - TS lo - TS kV Arizona Public Service Company None 230kV AC To be determined (f) Length To be determined Routing Purpose Date (a) Construction Start (b) Estimated In Service Sun Valley substation to be in-service by 2015; Sec. 29, T4N, R4W A future TS 1 0 substation; location to be determined A future TSII substation; location to be determined The routing for this line has not yet been determined. This project is needed to provide a transmission source to serve future load that emerges in the currently undeveloped areas northwest of the White Tank Mountains. This line is anticipated to be a 230kV line originating from the Sun Valley substation, with the future TSI0 230/69kV substation to be interconnected into the 230kV line. To be determined To be determined Permitting I Siting Status An application for a Certificate of Environmental Compatibility has not yet been filed. -33-

37 Page 37 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation Buckeye - TS 11 - Sun Valley 230kV Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company None 230kV AC To be determined (f) Length To be determined Routing Sun Valley substation to be in-service by 2015; Sec. 29, T4N, R4W A future TS 11 substation; location to be determined Buckeye substation; Sec. 7, TIN, R3W The routing for this line has not yet been determined. Purpose Date (a) Construction Start (b) Estimated In Service Permitting I Siting Status This project will serve the need for electric energy in the largely undeveloped areas west of the White Tank Mountains. This project will provide the first portion of the transmission infrastructure in this largely undeveloped area and will provide a transmission connection between the northern and southern transmission sources that will serve the area. Improved reliability and continuity of service will result for this portion of Maricopa County. It is anticipated that this project will be constructed with double-circuit capability, but initially operated as a single circuit. The in-service date and location of the TSII kV substation will be determined in future planning studies based upon the development of the area. To be determined To be determined An application for a Certificate of Environmental Compatibility has not yet been filed. -34-

38 Page 38 of 149 Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Designation Project Sponsor Raceway - Westwing 230kV Arizona Public Service Company Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination None 230kV AC To be determined Westwing substation; Sec. 12, T4N, RIW Raceway substation; Sec. 4, T5N, RIB (f) Length Approximately 7 miles Routing Northeast from Westwing substation paralleling existing transmission lines to the Raceway 230kV substation. Pumose Date (a) Construction Start To be determined (b) Estimated In Service Permitting / Siting Status This project will serve the need for electric energy in the far north and northwest parts of the Phoenix Metropolitan area and provide contingency support for multiple Westwing kV transformer outages. The in-service date will continue to be evaluated in future planning studies. To be determined Certificate of Environmental Compatibility issued 6/18/03 (Case No. 120, Decision No , North Valley 230kV smission Project). -35-

39 Page 39 of 149 Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection (e) Point of Termination Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined E1 Sol- Westwing 230kV Arizona Public Service Company None 230kV AC To be determined Westwing substation; Sec. 12, T4N, R1W E1 Sol substation; Sec. 30, T3N, R1E (f) Length Approximately 11 miles Routing erally following the existing Westwing-Surprise-E1 Sol 230kV corridor. Purpose This project will increase system capacity to serve the Phoenix Metropolitan area, while maintaining system reliability and integrity for delivery of bulk power from Westwing south into the APS Phoenix Metropolitan area 230kV transmission system. Date (a) Construction Start (b) Estimated In Service Permitting / Siting Status To be determined To be determined Certificate of Environmental Compatibility issued 7126/73 (Case No.9, Docket No. U-1345). Note that this Certificate authorizes two double-circuit lines. Construction of the first double-circuit line was completed in March Construction of the second line, planned to be built with double-circuit capability, but initially operated with a single circuit, is described above. -36-

40 Page 40 of 149 Designation Project Sponsor Other Participants Size (a) Voltage Class (b) Facility Rating (c) Point of Origin (d) Intermediate Points of Interconnection Arizona Public Service Company Ten-Year Plan Planned smission Description To Be Determined Palo Verde - Saguaro SOOkV CATS Sub-Regional Planning Group Participants To be determined SOOkV AC To be determined Palo Verde switchyard; Sec. 34, TIN, R6W (e) Point of Termination Saguaro substation; Sec. 14, TIOS, RlOE (f) Length Approximately 130 miles Routing Purpose Date (a) Construction Start To be determined (b) Estimated In Service erally south and east from the Palo Verde area to a point near Gillespie Dam, then generally easterly until the point at which the Palo Verde-Kyrene SOOkV line diverges to the north and east. The corridor then continues generally south and east again, adjacent to a gas line corridor, until converging with the Tucson Electric Power Company's Westwing-South 34SkV line. The corridor follows the 34SkV line until a point due west ofthe Saguaro erating Station. The corridor then follows a lower voltage line into the SOOkV yard just south and east of the Saguaro erating Station. The line will be needed to increase the adequacy of the existing EHV transmission system and permit increased power delivery throughout the state. To be determined Permitting / Siting Status Certificate of Environmental Compatibility issued (Case No. 24, Decision No ). -37-

41 Page 41 of 149 A subsidiary of Pinnacle West Capital Corporation TRANSMISSION PLANNING PROCESS AND GUIDELINES APS smission Planning January 2012

42 Page 42 of 149 TRANSMISSION PLANNING PROCESS AND GUIDELINES I. INTRODUCTION and PURPOSE... 1 II. PLANNING METHODOLOGY A. eral... l B. smission Planning Process EHV smission Planning Process kV smission Planning Process smission Facilities Required for erationlresource Additions... 3 C. Ten Year smission System Plans...4 D. Regional Coordination Planning Western Electricity Coordinating CounciL Sub-Regional Planning Groups WestConnect Joint Studies... 5 E. eration Schedules... 5 F. Load Projections... 6 G. Alternative Evaluations eral Power Flow Analyses sient Stability Studies Short Circuit Studies Reactive Power Margin Analyses Losses Analyses sfer Capability Studies Sub synchronous Resonance (SSR) FACTS Economic Evaluation... 8

43 Page 43 of 149 III. PLANNING ASSUMPTIONS A. eral 1. Loads eration and Other Resources Nominal Voltage Levels Sources of Databases Voltage Control Devices Phase Shifters Conductor Sizes kV System Modeling Substation sformers a. 500kV & 345kV Substations b. 230kV Substations Switchyard Arrangements a. 500kV & 345kV Substations b. 230kV Substations Series Capacitor Application Shunt and Tertiary Reactor Application B. Power Flow Studies 1. System Stressing Displacement C. sient Stability Studies 1. Fault Simulation Margin Unit Tripping Machine Reactance Representation Fault Damping Series Capacitor Switching D. Short Circuit Studies 1. eration Representation Machine Reactance Representation

44 Page 44 of Representation sformer Representation E. Reactive Power Margin Studies IV. SYSTEM PERFORMANCE A. Power Flow Studies 1. Normal (Base Case Conditions) a. Voltage Levels 1) eral ) Specific Buses b. Facilities Loading Limits 1) smission s ) Underground Cable ) sformers ) Series Capacitors c. Interchange ofvars d. Distribution of Flow Single Contingency Outages a. Voltage Levels b. Facilities Loading Limits 1) smission s ) Underground Cable ) sformers ) Series Capacitors c. erator Units d. Impact on Interconnected Systems B. sient Stability Studies Fault Simulation Series Capacitor Switching System Stability Re-closing iii

45 Page 45 of 149 C. Short Circuit Studies D. Reactive Power Margin Studies IV

46 Page 46 of 149 I. INTRODUCTION AND PURPOSE The smission Planning Process and Guidelines (Guidelines) are used by Arizona Public Service Company (APS) to assist in planning its Extra High Voltage (EHV} transmission system (345kV and 500kV) and High Voltage transmission system (230kV and 115kV). In addition to these Guidelines, APS follows the Western Electricity Coordinating Council's (WECC) regional planning reliability criteria for system disturbance and performance levels. These WECC Reliability Criteria are (1) WECCINERC Reliability Criteria for smission System Planning and (2) Minimum Operating Reliability Criteria, which can be found III their entirety on the WECC website; ( pdf). These Guidelines are for internal use by APS and may be changed or modified. Thus, others should not use these Guidelines without consultation with APS. II. PLANNING METHODOLOGY A. eral APS uses a deterministic approach for transmission system planning. Under this approach, system performance should meet certain specific criteria under normal conditions (all lines in-service) and for any single contingency condition (anyone element out-of-service). In general, an adequately planned transmission system will: Provide an acceptable level of service that is cost-effective for normal and single contingency operating conditions. Maintain service to all firm loads for any single contingency outage; except for radial loads. Not result in overloaded equipment or unacceptable voltage conditions for single contingency outages. Not result in cascading for single or double contingency outages. Provide for the proper balance between the transmission import capability and local generation requirements for an import limited load area.

47 Page 47 of 149 Although APS uses a deterministic approach for transmission system planning, the WECC reliability planning criteria provides for exceptions based upon a probabilistic approach. APS uses these probabilistic criteria when/where appropriate in the transmission planning process. Historical system reliability performance is analyzed on a periodic basis and the results are used in the design of planned facilities. These planning methodologies, assumptions, and guidelines are used as the basis for the development of future transmission facilities. Additionally, consideration of potential alternatives to transmission facilities (such as distributed generation or new technologies) is evaluated on a case-specific basis. As new planning toolsandlor information become available revisions or additions to these guidelines will be made as appropriate. B. smission Planning Process APS's transmission planning process consists of an assessment of the following needs: Provide adequate transmission to access designated network resources in-order to reliably and economically serve all network loads. Support APS's and other network customers' local transmission and sub-transmission systems. Provide for interconnection for new resources. Accommodate requests for long-term transmission access. During this process, consideration is given to load growth patterns, other system changes affected by right-of-way, facilities siting constraints, routing of future transportation corridors, and joint planning with neighboring utilities, governmental entities, and other interested stakeholders (see APS OA TT Attachment (E)). 1. EHV smission Planning Process APS's EHV transmission system, which consists of 500kV and 345kV, has primarily been developed to provide transmission to bring the output of large base-loaded generators to load centers, such as Phoenix. Need for new 2

48 Page 48 of 149 EHV facilities may result from any of the bullet items described above. APS's annual planning process includes an assessment of APS's transmission capability to ensure that designated network resources can be accessed to reliably and economically serve all network loads. In addition, biennial Reliability Must-Run (RMR) studies are performed to ensure that proper balance between the transmission import capability and local generation requirements for an import limited load area are maintained kV smission Planning Process APS's 230kV transmission system has primarily been developed to provide transmission to distribute power from the EHV bulk power substations and local generators to the distribution system and loads throughout the load areas. Planning for the 230kV system assesses the need for new 230/69kV substations to support local sub-transmission and distribution system growth and the reliability performance of the existing 230kV system. This process takes into account the future land use plans that were developed by government agencies, Landis aerial photo maps, master plans that were provided by private developers, and APS' s long-range forecasted load densities per square mile for residential, commercial, and industrial loads. 3. smission Facilities Required for eration/resource Additions New transmission facilities may also be required in conjunction with generation resources due to (I) a "merchant" request by an Independent Power Producer (IPP) for generator interconnection to the APS system, (2) a "merchant" request for point-to-point transmission service from the generator (receipt point) to the designated delivery point, or (3) designation of new resources or re-designation of existing units to serve APS network load (including removal of an older units' native load designation). These studies/processes are performed pursuant to the APS Open Access smission Tariff (OATT). 3

49 Page 49 of 149 C. Ten Year smission System Plans Each year APS uses the planning process described in section B to update the Ten-Year smission System Plan. The APS Ten Year smission System Plan identifies all new transmission facilities, 115kV and above, and all facility replacements/upgrades required over the next ten years to reliably and economically serve the load. D. Regional Coordinated Planning 1. Western Electricity Coordinating Council (WECC) APS is a member of the WECC. The focus of the WECC is promoting the reliability of the interconnected bulk electric system. The WECC provides the means for: Developing regional planning and operating criteria. Coordinating future plans. Compiling regional data banks for use by the member systems and the WECC in conducting technical studies. Assessing and coordinating operating procedures and solutions to regional problems. Establishing an open forum with interested non-project participants to review the plan of service for a project. Through the WECC smission Expansion Policy Committee, performing economic transmission congestion analysis. APS works with WECC to adhere to these planning practices. 2. Sub-Regional Planning Groups Southwest Area smission Planning (SWAT) and other sub-regional planning groups provide a forum for entities within a region, and any other interested parties, to determine and study the needs of the region as a whole. It also provides a forum for specific projects to be exposed to potential partners and allows for joint studies and participation from interested parties. 4

50 Page 50 of WestConnect APS and the other WestConnect members executed the WestConnect Project Agreement for Subregional smission Planning in May of This agreement promotes coordination of regional transmission planning for the WestConnect planning area by formalizing a relationship among the WestConnect members and the WestConnect area sub-regional planning groups including SWAT. The agreement provides for resources and funding for the development of a ten year integrated regional transmission plan for the WestConnect planning area. The agreement also ensures that the WestConnect transmission planning process will be coordinated and integrated with other planning processes within the Western Interconnection and with the WECC planning process. 4. Joint Studies In many instances, transmission projects can serve the needs of several utilities and/or IPPs. To this end, joint study efforts may be undertaken. Such joint study efforts endeavor to develop a plan that will meet the needs and desires of all individual companies involved. E. eration Schedules For planning purposes, economic dispatches of network resources are determined for APS's system peak load in the following manner: a. Determine base generation available and schedule these units at maximum output. b. Determine resources purchased from other utilities, IPPs, or power marketing agencies. c. Determine APS's spinning reserve requirements. d. Schedule intermediate generation (oil/gas steam units) such that the spinning reserve requirements, in section (c) above, are met. e. Determine the amount of peaking generation (combustion turbine units) required to supply the remaining system peak load. 5

51 Page 51 of 149 Phoenix area network resources are dispatched based on economics and any existing import limitations. When possible, spinning reserve will be carried on higher cost Phoenix area network generating units. eration output schedules for interconnected utilities and IPPs are based upon consultation with the neighboring utilities and IPPs or as modeled in the latest data in WECC coordinated study cases. F. Load Projections APS substation load projections are based on the APS Corporate Load Forecast. Substation load projections for neighboring interconnected utilities or power agencies operating in the WECC area are based on the latest data in WECC coordinated study cases. Heavy summer loads are used for the Ten-Year smission System Plans. G. Alternative Evaluations 1. eral In evaluating several alternative plans, compansons of power flows, transient stability tests, and fault levels are made first. After the alternatives are found that meet the system performance criteria in each of these three areas comparisons may be made of the losses, transfer capability, impact on system operations, and reliability of each of the plans. Finally, the costs of facility additions (capital cost items), costs of losses, and relative costs of transfer capabilities are determined. A brief discussion of each of these considerations follows. 2. Power Flow Analyses Power flows of base case (all lines in-service) and single contingency conditions are tested and should conform to the system performance criteria set forth in Section IV of these Guidelines. Double or multiple contingencies are examined, but in general, no facilities are planned for such conditions. Normal system voltages, voltage deviations, and voltage extreme limitations are based upon operating experience resulting in acceptable voltage levels to 6

52 Page 52 of 149 the consumer. Power flow limits are based upon the thermal ratings and/or sag limitations of conductors or equipment, as applicable. 3. sient Stability Studies Stability guidelines are established to maintain system stability for single contingency, three-phase fault conditions. Double or multiple contingencies are examined, but in general, no facilities are planned for such conditions. 4. Short Circuit Studies Three-phase and single-phase-to-ground fault studies are performed to ensure the adequacy of system protection equipment to clear and isolate faults. 5. Reactive Power Margin Analyses Reactive Power Margin analyses are performed when steady-state analyses indicate possible insufficient voltage stability margins. V -Q curve analyses are used to determine post-transient voltage stability. 6. Losses Analyses A comparison of individual element and overall transmission system losses are made for each alternative plan being studied. The losses computed in the power flow program consist of the er losses of lines and transformers and the core losses in transformers, where represented. 7. sfer Capability Studies In evaluating the relative merits of one or more EHV transmission plans, both simultaneous and non-simultaneous transfer capability studies are performed to determine the magnitude of transfer capabilities between areas or load centers. 8. Sub synchronous Resonance (SSR) SSR phenomenon result from the use of series capacitors in the network where the tuned electrical network exchanges energy with a turbine generator at one or more of the natural frequencies of the mechanical system. SSR countermeasures are applied to prevent damage to machines as a result of transient current or sustained oscillations following a system disturbance. SSR studies are not used directly in the planning process. SSR countermeasures are determined after the transmission plans are finalized. 7

53 Page 53 of FACTS (Flexible AC smission System) F ACTS devices are a recent application of Power Electronics to the transmission system. These devices make it possible to use circuit reactance, voltage magnitude and phase angle as control parameters to redistribute power flows and regulate bus voltages, thereby improving power system operation. FACTS devices can provide series or shunt compensation. These devices can be used as a controllable voltage source in series or as a controllable current source in shunt mode to improve the power transmission system operations. FACTS will be evaluated as a means of power flow control and/or to provide damping to dynamic oscillations where a need is identified and it is economically justified. 10. Economic Evaluation In general, an economic evaluation of alternative plans consists of a cumulative present worth or equivalent annual cost comparison of capital costs. III.PLANNING ASSUMPTIONS A. eral 1. Loads Loads used for the APS system originate from the latest APS Corporate Load Forecast. In most cases, the corrected power factor of APS loads is 99.5% at 69kV substations. 2. eration and Other Resources eration dispatch is based on finn power and/or transmission wheeling contracts including network resources designations. 3. Nonnal Voltage Levels a. Nominal EHV design voltages are 500kV, 345kV, 230kV, and 115kV. b. Nominal EHV operating voltages are 535kV, 348kV, 239kV, and 119kV. 8

54 Page 54 of Sources of Databases WECC Heavy Summer base cases are the sources of the databases. Loop flow (unscheduled flow), of a reasonable amount and direction, will be allowed for use in planning studies. 5. Voltage Control Devices Devices which can control voltages are shunt capacitors, shunt reactors, tap-changing-under-ioad (TCUL) and fixed-tap transformers, static Volt Ampere Reactive (V AR) compensators, and machine V AR capabilities. If future voltage control devices are necessary, these devices will be evaluated based upon economics and the equipment's ability to obtain an adequate voltage profile on the EHV and HV systems. 6. Phase Shifters In general, where phase shifters are used, schedules are held across the phase shifter in base case power flows and the phase shifter tap remains fixed in the outage cases. 7. Conductor Sizes Existing transmission voltages utilized by APS are 230kV, 34SkV, and SOOkV. It is presently planned that the 34SkV transmission system will not be expanded, thus all future APS EHV lines will be SOOkV or 230kV. Planned SOOkV lines will initially be modeled using tri-bundled 1780 kcm ACSR conductor (Chukar). Preferred construction for 230kV lines consists of 2156 kcm ACSS conductor on steel poles kV System Modeling 230kV facility outages may result in problems to the underlying 69kV system due to the interconnection of those systems. For this reason, power flow cases include a detailed 69kV system representation. Solutions to any problems encountered on the 69kV system are coordinated with the subtransmission planning engineers. 9

55 Page 55 of Substation sfonners a. SOOkV and 34SkV Substations Bulk substation transfonner banks may be made up of one three-phase or three single-phase transfonners, depending upon bank size and economics. For larger banks where single-phase transfonners are used, a fourth (spare) single-phase transfonner will be used in a jack-bus arrangement to improve reliability and facilitate connection of the spare in the event of an outage of one of the single-phase transfonners. TCUL will be considered in the high voltage windings, generally with a range of plus or minus 10%. High voltage ratings will be SOOkV or 34SkV class and low voltage windings will be 230kV, IISkV, or 69kV class. b. 230kV Substations For high-density load areas, both 230/69kV and SkV transfonners can be utilized. 230/69kV transfonners will be rated at 11311S01188 MV A with a 6SoC temperature rise, unless otherwise specified SkV transfonners will be rated at 2S/33/41 MVA with a 6SoC temperature rise, unless otherwise specified. With all elements in service, a transfonner may be loaded up to its top Forced Oil Air (FOA) rating without sustaining any loss of service life. For a single contingency outage (loss of one transfonner) the remaining transfonner or transformers may be loaded up to 20% above their top FOA rating, unless heat test data indicate a different overload capability. The loss of service life sustained will depend on the transfonner pre-loading and the outage duration. Tap setting adjustment capabilities on 230/69kV transfonners will be ±S% from the nominal voltage setting (230/69kV) at 2Y2% increments. 10. Switchyard Arrangements a. SOOkV and 34SkV Substations Existing 34SkV switchyard arrangements use breaker-and-one-half, main-and-transfer, or modified paired-element circuit breaker switching 10

56 Page 56 of 149 schemes. Because of the large amounts of power transferred via SOOkY switchyards and the necessity of having adequate reliability, all SOOkY circuit breaker arrangements are planned for an ultimate breaker-and-onehalf scheme. If only three or four elements are initially required, the circuit breakers are connected in a ring bus arrangement, but physically positioned for a breaker-and-one-half scheme. The maximum desired number of elements to be connected in the ring bus arrangement is four. System elements such as generators, transformers, and lines. will be arranged in breaker-and-one-half schemes such that a failure of a center breaker will not result in the loss of two lines routed in the same general direction and will minimize the impact of losing two elements. b. 230kV Substations Future 230/69kV substations should be capable of serving up to 452 Megavolt-Amps (MV A) of load. 400 MV A has historically been the most common substation load level in the Phoenix Metropolitan area. Future, typical 230/69kV substations should accommodate up to four 230kV line terminations and up to three 230/69kV transformer bays. Based upon costs, as well as reliability and operating flexibility considerations, a breaker-and-one-half layout should be utilized for all future 230/69kV Metropolitan Phoenix Area substations, with provision for initial development to be a ring bus. Any two 230/69kV transformers are to be separated by two breakers, whenever feasible, so that a stuck breaker will not result in an outage of both transformers. 11. Series Capacitor Application Series capacitors may be used on EHV lines to increase system stability, for increased transfer capability, andlor for control of power flow. The series capacitors may be lumped at one end of a line because of lower cost; however, the capacitors are generally divided into two banks, one at either end of a line, for improved voltage profile. 11

57 Page 57 of Shunt and Tertiary Reactor Application Shunt and/or tertiary reactors may be installed to prevent open end line voltages from being excessive, in addition to voltage control. The open end line voltage must not be more than 0.05 per unit voltage greater than the sending end voltage. Tertiary reactors may also be used for voltage and V AR control as discussed above. B. Power Flow Studies 1. System Stressing Realistic generation capabilities and schedules should be used to stress the transmission system in order to maximize the transfer of resources during the maximum load condition. 2. Displacement In cases where displacements (due to power flow opposite normal generation schedules) may have an appreciable effect on transmission line loading, a reasonable amount of displacement (eration Units) may be removed in-order to stress a given transmission path. C. sient Stability Studies 1. Fault Simulation When studying system disturbances caused by faults, two conditions will be simulated: a. Three-phase-to-ground faults, and b. Sing1e-1ine-to-ground faults with a stuck circuit breaker in one phase with back-up delayed clearing. 2. Margin a. eration margin may be applied for the contingencies primarily affected by generation, or b. Power flow margin may be applied for the contingencies primarily affected by power flow. 12

58 Page 58 of Unit Tripping erator unit tripping may be allowed in-order to Increase system stability performance. 4. Machine Reactance Representation For transient stability studies, the unsaturated transient reactance of machines with full representation will be used. 5. Fault Damping Fault damping will be applied to the generating units adjacent to faults. Fault damping will be determined from studies that account for the effect of generator amortisseur windings and the SSR filters. 6. Series Capacitor Switching Series capacitors, locations to be determined from short circuit studies, will be flashed and reinserted as appropriate. D. Short Circuit Studies Three-phase and single-phase-to-ground faults will be evaluated. 1. eration Representation All generation will be represented. 2. Machine Reactance Representation The saturated subtransient reactance (X" d) values will be used. 3. Representation The transmission line zero sequence impedance (Xo) is assumed to be equal to three times the positive sequence impedance (Xl). 4. sformer Representation The transformer zero sequence impedance (Xo) is assumed to be equal to the positive sequence impedance (Xl). Bulk substation transformers are modeled as auto-transformers. The two-winding model is that of a groundedwye transformer. The three-winding model is that of a wye-delta-wye with a solid ground. 13

59 Page 59 of 149 E. Reactive Power Margin Studies Using Q-V curve analyses, APS assesses the interconnected transmission system to ensure there are sufficient reactive resources located throughout the electric system to maintain post-transient voltage stability for system normal conditions and certain contingencies. IV. SYSTEM PERFORMANCE A. Power Flow Studies 1. Normal (Base Case Conditions) a. Voltage Levels 1) eral (a) SOOkV bus voltages will be maintained between LOS and 1.08 p.u. on a SOOkV base. (b) 34SkV bus voltages will range between.99 and 1.04 p.u. on the 34SkV system. (c) SOOkV and 34SkV system voltages are used to maintain proper 230kV bus voltages. (d) Voltage on the 230kV and l1skv system should be between 1.01 p.u. and 1.0S p.u. (e) Tap settings for 230/69kV and 34S/69kV transformers should be used to maintain low side (69kV) voltages of 1.03 to 1.04 p.u. Seasonal tap changes may be required. 2) Specific Buses (a) APS Pinnacle Peak 230kV bus voltage should be between 1.02S p.u. and 1.03S p.u. (b) APS Westwing 230kV bus voltage should be between 1.04 p.u. and LOS p.u. (c) Saguaro 11SkV bus voltage will be approximately 1.03S p.u. (d) Voltage at the Prescott (DOE) 230kV bus should be approximately 1.02 p.u. 14

60 Page 60 of 149 b. Facility Loading Limits 1) smission s smission line loading cannot exceed 100% of the continuous.rating, which is based upon established conductor temperature limit or sag limitation. 2) Underground Cable Underground cable loading should not exceed 100% of the continuous rating with all elements in service. This rating is based on a cable temperature of 85 C with no loss of cable life. 3) sformers sformers cannot exceed 100% of top FOA, 65 C rise, nameplate ratings. 4) Series Capacitors Series Capacitors cannot exceed 100% of continuous rating. c. InterchangeofVARs Interchange of V ARs between companies at interconnections will be reduced to a minimum and maintained near zero. d. Distribution of Flow Schedules on a new project will be compared to simulated power flows to ensure a reasonable level of flowability. 2. Single Contingency Outages a. Voltage Levels Maximum voltage deviation on APS's major buses cannot exceed 5%. This deviation level yields a close approximation to the post-transient V AR margin requirements of WECC. b. Facilities Loading Limits 1 ) smission s smission line loading cannot exceed 100% of the lesser of the sag limit or the emergency rating (30-minute rating) which is based upon established conductor temperature limits. 15

61 Page 61 of 149 2) Underground Cable Underground cable loading should not exceed the emergency rating during a single-contingency outage. This rating is based on a cable temperature of 105 C for two hours of emergency operation with no loss of cable life. 3) sformers sformers cannot exceed 120% of top FOA, 65 C TIse, nameplate ratings. 4) Series Capacitors Series Capacitors cannot exceed 100% of emergency rating. c. erator Units erator units used for controlling remote voltages will be modified to hold their base case terminal voltages. d. Impact on Interconnected System Single contingency outages will not cause overloads upon any neighboring transmission system. B. sient Stability Studies sient stability studies are primarily performed on the 500kV and 345kV systems. 1. Fault Simulation Three-phase-to-ground faults and single-line-to-ground faults, simulating a stuck circuit breaker in one phase with back-up delayed clearing will be simulated. Fault clearing times of four cycles after fault inception (5 cycles for a 230kV fault) and a back-up clearing time of twelve cycles after fault inception is utilized. System elements are switched out at the appropriate clearing times, as applicable. Fault damping will be applied when applicable at fault inception. 16

62 Page 62 of Series Capacitor Switching Series capacitors, at locations determined from short-circuit studies, will be flashed at fault inception and will be reinserted depending on their reinsertion types. 3. System Stability The system will be considered stable if the following conditions are met: a. All machines in the system remain synchronized as demonstrated by the relative rotor angles. b. Positive system damping exists as demonstrated by the damping of relative rotor angles and the damping of voltage magnitude swings. For N-I disturbances, voltages for the first swing after fault clearing should not drop below 75% of pre-fault value with maximum time duration of20 cycles for voltage dip exceeding 20%. 4. Re-closing Automatic re-closing of circuit breakers controlling EHV facilities is not utilized. C. Short Circuit Studies Fault current shall not exceed 100% of the applicable breaker fault current interruption capability for three-phase or single-line-to-ground faults. D. Reactive Power Margin Studies For system normal conditions or single contingency conditions, posttransient voltage stability is required with a path or load area modeled at a minimum of 105% of the path rating or maximum planned load limit for the area under study, whichever is applicable. For multiple contingencies, post-transient voltage stability is required with a path or load area modeled at a minimum of 102.5% of the path rating or maximum planned load limit for the area under study, whichever is applicable. 17

63 Page 63 of SYSTEM RATING MAPS PREPARED BY smission Planning and Operations Aug 2011

64 Page 64 of 149 TABLE OF CONTENTS LEGEND c EHV METRO 230KV ~. 6 NORTHERN 230KV ---~ SOUTHERN 230KV --~ METRO EAST METRO CENTRAL WESTERN NORTHEAST ~ 20 NORTHWEST SOUTHEAST ~ SOUTHWEST

65 Page 65 of 149 LEGEND SYSTEM RATING MAPS I SYMBOL ### - ### ### DESCRIPTION CURRENT LIMIT IN AMPS LIMITING ELEMENT CONDUCTOR LIMIT IN AMPS TRANSFORMER LIMITS ARE IN MVA OVERHEAD TRANSMISSION LINE UNDERGROUND CABLE M V H MOTOR OPERATED SWITCH VACCUM SWITCH HYDRAULIC SWITCH BREAKER NUMBER 1

66 CRYSTAL Attachment A Page 66 of 149 NAVAJO DUGAS CYX 3000 # Switch ---~ 600MVA t KV 2200 Ca~acitors Capacitor C PINNACLE #1 PEAK 600MVA...--'--7) KV PP 230KV #6 capacitor C4 600MVA KV ~ KV Capacitor C5 =r Capacitor 1810 C7 T r!j ~ ~ #1AA MVA ELDORADO L KV EOX 2250 #3 FOUR CORNERS (SCE) Capacitor C ('1 336 MVA " FC KV NV DGS ~ ~~OMVA ~ [!l 69KV 500KV MOENKOPI MK #2 600MVA 230KV I, EHV-1 ~ PANDA PND- ~ #1 336 MVA 230KV 1750 Capacitor C MVAuk 230KV r , MEAD a MEX CAPS 4290 N m DEVERS DEX ') '" IMPERIAL VALLEY IVX j--220r>-----=! = NORTH GILA NG #1 240 MVA 69KV 2200 Capacitor C #4 240 MVA 69KV '1 T' ; #1A ~!U~VA ~ I ~ 4J ~ ljj I PALO VERDE PLX I 635 MVA 230kV #3A #38 > 635 MVA ~ 635 MVA 230kV 230kV ~ 4J #7 672 MVA 345KV # MVA 230KV # SWITCHES MVA KV I SWITCHES 4017 :> TO I JOJOBA 4017 ~REDHAWK JJX ~ I ~ KYRENE KYX 3430 ~ TO PINAL WEST

67 CRYSTAL CYX t mo Attachment A Page 67 of ,------,; NAVAJO NV I EMERGENCY RATING (AMPS)] DUGAS DGS #2 ~ 3 270MVA r ~ 3 69KV "'--7)~ 500KV r ) J ~ 500KV ELDORADO EOX (SCE) =l #2 750MVA 230KV #1 750MVA 230KV #3 750MVA 230KV PINNACLE PEAK PP #6 600MVA 230KV =l r ~3 ~ ~ 2760 L #3.----<~ 395 MVA 230KV #1 395 MVA 230KV ~ 2362 EHV-1 EMERGENCY RATINGS #1AA ~ I MVA FOUR CORNERS 345KV FC PANDA PND ~ 500 MVAuk 230KV GILA RIVER r~ GLX MEAD MEX a-2970 I) m DEVERS DEX c".) IMPERIAL VALLEY IVX i--297<>-----=r" """F :::c..r::c NORTH GILA NG 1'---' r ~ l' 3000 =l r--"t""""""t---:~~~lt~va ~ ~ LfJ 6lfJ 6 # MVA #3A 230kV> 717 MVA '-r' ~ '~ MVA 230kV 230kV PALO VERDE PLX ' , , LjJ # MVA 230KV #7 806 MVA 345KV # MVA 230KV. I > TO I JOJOBA 5019 ~ REDHAWK JJX ~ I ~ KYRENE KYX 4100 ~ TO PINAL WEST

68 Page 68 of 149 [, EHV-2 [I " #6 500 MVA FOURCORNERS ri ~~-----.~ MOENKOPI M ~ FC _ C7 K OOKV. Capacitors ' , #8 143 MVA 69KV 1750 Capacitors - C ) '-----' TO ~ SAN 1800~JUAN ~ 2000 t TO CORONADO #4 r---t--~--~1 725MVA 115KV #7 725 MVA 115KV 'J t TORTOLITA TOX 1256 PREACHER CANYON PR ~~ 100#AAvA t'- 69KV # MVA 230KV #7 I 1 ~ 625MVA 230KV 345KV PINNACLE PEAK pp 1--' «~ 50 ~VA ~ 69KV EMISSION ABATEMENT-~.r~---' #1 780 ~~~ # 2 I :> C";'VA A EMISSION BA';f,MENT FC-69 TO PILLAR

69 Page 69 of EMERGENCY RATING (AMPS) EHV-2 EMERGENCY RATINGS #6 750 MVA MOENKOPI~8 FOURCORNERS r, ~~-----r~ FC MK 500KV I. ~ ~ ~ ~ ~ #8 160 MVA 69KV 2362 SUGARLOAF 221 SLF l) ' TO ~ SAN 1800~JUAN U1 2~0 TO CORONADO #4 r-----~--~----~~ 835MVA 115KV #7 835 MVA 115KV 1371 ~ TORTOLITA TOX 1428 #4 875 MVA 230KV PREACHER CANYON PR ~ ~ ~ 11l~VA ~ 69KV # MVA 230KV #7 I 1 ~ 700MVA 345KV PINNACLE PEAK PP 230KV J...IL--<~ ~ 50 flva ~ 69KV EMISSION ABATEMENT~.c~--~ #1 #8 625 MVA 1009 ~n # 2 ' > A~MISSION ;A ATffi,MENT CSO FC-69 TO PILLAR.

70 #8 100 MVA 69KV Attachment A Page 70 of 149 GILA BEND GB WADDELL #12 W~AX 100 MVA 6 69KV #14 # MVA 188 MVA 69KV 69KV I, METRO 230KV ~ 502 GBXFMRs DEER VALLEY PINJgCL~ 909.,Jj~ ~ DV PEAK, 1818~ SRP # MVA 69KV #8 188 MVA 69KV # MVA 500KV ~ TO 1800~ LIBERTY #14 1-;'8 188 MVA 69KV TO ALEXANDER AXR #3 188 MVA 69KV ±, ll! PALM VALLEY PV 3000 SWITCH 3098 TO SRP WTX L MVA 2~~ TO GILA RIVER LIBERTY. LBX 3000 : WAPA 1099~. #4 188 MVA 69KV 1850 # ~~~ 1~89~~A #1 SUNNYSLOPE 188 MVAy S 69KV EL SOL I # I ES ~ ~A ~. AGUA FRIA : AFX L - # ~ ~~A ~ #8 '----~. 188 MVA 69KV I GLENDALE. GL ***- -, I #1 188 MVA 69KV MEADOWBROOK _ 900~ _ ME 1--' l 1 #9 187 MVA 69KV I ' I #6 187 MVA 69KV # MVA 69KV # MVA 69KV # MVA 69KV PINNACLE PEAK SOUTH PP2S r ' #1 188MVA~ 69KV #6 167 MVA 69KV 937 TO BRANDON SRP TO 900~ KYRENE TO LIBERTY tvyy\ fy'(f' 1~ 2100 ~ LINCOLN STREET LS # MVA 69KV OCOTILLO OC en TO RUDD 500KV # MVA 69KV it Dynamic Rating ** No forced cooling on GT-CC, Cooling both ends LS-CC Forced cooling on GT-CC, Cooling one end LS-CC

71 #8 100 MVA 69KV Attachment A Page 71 of 149 GILA BEND GB WADDELL WAX 100 #12 MVA ~ 6 69KV METRO 230KV EMERGENCY RATINGS ] #8 188 MVA 69KV # MVA 500KV TO 1800~ LIBERTY DEER VALLEY PINJ.l'CLE' DV PEAK 2000~ SRP ;=== 1126 ~,=~=---==-..J # MVA 69KV 750#~VA T0 500KV PP WAPA~ # MVA t' 69KV TO ALEXANDER AXR 2000 #3 188 MVA T r-.l...--i~ PALM VALLEY PV 3000 TO SRP WTX L 500 MVA ~~ TO GILA RIVER 1233 LIBERTY, LBX 3000 ' 1367 I : WAPA ~ #4 ' 188 MVA 69KV 2000 # :J~~ 1 ~89~~A #1 SUNNYSLOPE 188 MVAy S 69KV EL SOL I #3 I ES ~ ~A ~ AGUA FRIA : AFX L - #5 t-.---:j~~186~~~a #8 L..----:J~~ 188 MVA 69KV 2164 #1 188 MVA 69KV #9 ~~G~~~~L_E _, 1740, MEADOWBROOK _ 1875~ _ ME I I #6 187 MVA 69KV COUNTRY CLUB CC #7 188 MVA 69KV J--L ~ 205 MVA 69KV # MVA 69KV # MVA 69KV PINNACLE PEAK SOUTH ' #1 188 MV A I 69KV PP2S ' #6 167 MVA 69KV 1034 TO BRANDON SRP TO LIBERTY # MVA 69KV OCOTILLO OC... TO RUDD 500KV # MVA 69KV

72 Page 72 of 149 TO PEACOCK." lsi I 112 ~J-- NELSON SUB FORT ROCK FT JUNIPER MTN JM SELIGMAN COMPRESSOR ; 8 RV CT RV CT RV CT XFMR SCE NORTHERN 230KV ~ 841 ROUND VALLEY RV # MVA 69KV VERDE VE LEUPP h LW #3,---, ' MVA <" I I M-.lM KV M #2 1--->~ 100 MVA 69KV 673 #1 83MVA 841 GAVILAN PEAK GV # MVA-+-L-l 69KV 188~VA~ 69KV r-----~l2j 770 WILLOW LAKE WL TO WAPA PPK 1255t #1 336 MVA 500KV 800 '------r-----il.!.l YAVAPAI YP #10 100MVA 69KV #3 336 MVA 500KV #4 167 MVA 69KV COCONINO CQ # MVA 69KV #7 203 MVA 345KV CHOLLA CH co #2 83 MVA 430 WL BUS COND~ TO BAGDAD 700 WILLOW LAKE 115KV # MVA 69KV

73 Page 73 of 149 TO PEACOCK NELSON SUB FORT ROCK. FT JUNIPER MTN JM I NORTHERN 230KV EMERGENCY RATINGS ~ APS [81 I 112~ ~ SELIGMAN COMPRESSOR ~ SCE 929 ROUND VALLEY RV # MVA 69KV LEUPP h LW PRESCOTT VERDE PRX VE M #3 (DOE) ' MVA... III(IE--H M~ M KV #2 1--"':~~ 100 MVA 69KV 930 #6 188MVA~ 69KV r ~----~ ) L:J 890 WILLOW LAKE WL #1 395 MVA 500KV 939 #10 100MVA 69KV #4 167 MVA 69KV COCONINO CQ # MVA 69KV #7 243 MVA 345KV CHOLLA CH #1 50 MVA 69KV 673 #1 83MVA GAVILAN PEAK GV #11 188MVA~ 69KV TO WAPA PPK J ' Il.!J YAVAPAI YP #3 ~ 395MVA 500KV CD #2 83MVA 570~ TO BAGDAD WILLOW LAKE 115KV # MVA 69KV

74 Page 74 of 149 I, SOUTHERN 230KV ~ SRP KNOX l1li( ~ 69KV ; SANTA ROSA SR. 'I TO > WAPA TEST TRACK ~ 2000, SWITCH ---~ J7l--l MARICOPA ~ MAX 900 ~ I 2986 KYRENE KYX ~ OCOTILLO OC 720. LAKESHORE r-- 900~ I LSX ~ ~ TAT MOMOLI ~ TL 720 ASA~1? PIT I 900 ~ ~ 658 TOLTEC TLT 1----' #2 100 MVA 69KV 900 SR EO-3 ~ 69KV 2000 SWITCH 2280 ~ ~ DESERT BASIN DBN CASA GRANDE CG r #~VAI 12KV I I 12KV... o L j E---f 115KV SAGUARO SG

75 ~ Attachment A Page 75 of 149 SRP KNOX -c ~>------~----~ 69KV SANTA ROSA SR TO I---~>~ WAPA TEST TRACK SOUTHERN 230KV EMERGENCY RATINGS J 69KV r , 967 ~ OCOTILLO OC ~ I 2986 KYRENE KYX LAKESHORE L-.900 LSX I 720 ~ + TAT MOMOLI ~ TL 720 ASA~1? PIT I r-r J7l--l MARICOPA ~ MAX. SR i f+, ~ ~ 2000 ~ E~ 69KV ~ ~ 658 TOLTEC TLT I I #2 100 MVA 69KV i131 i 1367 T 50#~VAI 12KV KV 4 ---' L...J L.. DESERT BASIN DBN CASA GRANDE CG L L..I-10 I OlE----! 115KV SAGUARO SG ~

76 Page 76 of 149 DUGAS ~1DGS25 r CHILDS v CZ I N.O. r ROCK SPRINGS RS TABLE MESA TM 225 I ' WILD BURRO H WBR I-,) 1600 # MVA 230kV # MVA 230kV r , DOVE VALLEY. DVY YORKSHIRE YK DEER VALLEY DV #7 188 MVA 230kV ~-L I I, METRO EAST 1 ~ LONEPEAK LP 900 ~ PARADISE ""7""'" Page ME ~ BUFFALO Page ME-2 #1 188 MVA 230kV , ~ MOON VALLEY AQUEDUCT 3 900~ ML AQ LOOKOUT 1 3 SUNNYSLOPE LK Page MC-1 PINNACLE PEAK PP W 1600 JOMAX JX I6U CAVE I ~ ICREEK 658 CA STAGECOACH STG NORTH VALLEY MONTE CRISTO NY MCR ~ Page MC I---SUB DISC -flomavista H # MVA kV 1600 # ~~8r,~ TURF ADOBE STT ~ 3 26 LA~IDE 1000~~~~~~ ~ TOUT TU AD RACEWAY 1000 I ~ v ~ HUMBUG 1600~ L4- TO G #8 ~ESTWING 188 MVA CALDERWOOD L PYRAMID kV CLW Page W ~ TO PYRAMID PEAK 9~0 3 A ~' ~900 7 DEADMAN PIONEER BISCUIT FLATS WASH PNR BCT DM 900 CIELO GRANDE CIG EAST END Page ME 2 ~ THOMPSON PEAK PageME-2 ~ RAWHIDE ~ 1600 PageME-2~ l '---'-L.'---' PINN PK PP 1640 t PINN PK Page ME-2 I I I I I I I

77 Page 77 of 149 PARADISE PD #4 r ~~~ 188MVA 230kV t :» 188~VA kV DIXILETA Page ME-1 t JOMAX 1600 JX [, METRO EAST - 2 n UNION HILLS page ME-1 BOULEVARD BV Page ME-2 ~ J LONE PEAK LP BUFFALO BF AQUEDUCT page ME-1 RoADRUNNER RR 900~ PINNACLE PK 5 PP DESERT RIDGE DG ~196:: -I ~900 DESERT SPRINGS DS ~ PINN PK Page ME-1 #3 188 MVA 230kV , ~16' '''''' TO.,.C, lbs oo, Page ME RAWHIDE RH ACOMA AA ' HGRANITE REEF 900 GRF W-- CENTURY CE ~ 3 INDIAN BEND L IB I k:d POLK DOUBLETREE SUNN~~lOPE To,-w~T'OO~ DT ~ t.) ~ ~900 40TH PLACE FP HOHOKAM HKM ~ / ~ TEMPE TP #1 187 MVA "'<~---i 230kV OCOTILLO OC I' 1600 BUTTE BU CAMELBACK CB 1600~ PINN PK Page ME CHAPARRAL CPL N.O. # il~~ 167 MVA 230kV # il~~ 167 MVA 230kV #14 i~1~~~~a J MCCORMICK 658 MC ~ ORANGEWOOD 7 OR I101-J MUMMY MTN. L.:.:.I I MM

78 Page 78 of 149 [ I METRO CENTRAL - 1 ~ BELL ~ 1000 BLL SKUNK CREEK SKC f-----1ooo------c:d1-&-9oo ~ ~ r ~ GREENWAY GW 13 1 MONTE CRISTO 1200 MCR 15L-MCR ~ 1530 DISC~ DEER VALLEY 3 DV. ~ ~... 01:>0 HONEYWELL HW r ~ 900 ~-- r I #0 188 MVA 230kV LOMAVISTA LV ~ ~~ CHERYL CRL 18rMVA~10 f kV 8 MUMMY MTN #1 1 ~~Jt~ A... rt 9?0 SHAW SH MM MEADOWBROOK ~ >- -' 658- ME 7 CAMELBACK page ME G1--l AGUA FRIA ~ AF ARROYO AY SUNNYSLOPE SS MOON VALLEY ML ~ "'--- LOOKOUT ~ pageme-2 3 li(r----t 1000 ROADRUNNER RR , #3 167 MVA 230kV ORANGEWOOD OR 900 ~ GRISWOLD GRW

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83 Page 83 of 149 I, WESTERN -4 ~ OBERLIN 0t BT PATTON PTN M i 900- V WICKENBURG WB MARTINEZ STANTON YARNELL MZW Nf SN YA KIRKLAND JCT. ~160~ IBC RELAY T ~ 37 r M ~~KJ M M--187~ ~ 187 RI J ON FLORES. WILHOIT WHITE SPAR RNC FLR POPLAR WASH WQ WSP 326 POP MCM 900 I 5 MORRISTOWN MQ BEARDSLEY BE FLYING E FE AGUILA AG 400 T CT L..-., BUCKEYE BK -,- M N.O. J I ~~ 14 LIBERTY LBX (DOE) ~I-----! 230kV SURPRISE SC BLACK PEAK BP L N.O. V-----,---L "> HA~~SU VICKSBURG VB ~ I :& 1 9 #4 50 MVA PARKER PAX (DOE) COPPERSTONE < WELLS CSW I QUARTZSITE QZ... (Q

84 N o MILLER WASH MLW CATARACT CREEK CK Attachment A Page 84 of 149 GRAND CANYON GC TUSAYAN TY RED BUTTE RD f----i WILAHA WX SAGE VALLEY SGV ~ VALLE VA --'----II NA~~SY I-----l RAMON ASO RA I l HOWARD MESA HM I l RED LAKE RL """"- CQ #1 ~ pagenw -1 TUBA CITY TC NAVAJO TONALEA HAMBLIN GAP COPPER LECHE BEAR SPRINGS BS CAMERON CM TQ HL, M G5 FOUR CORNERS 1-1 _M.1...!_----J NTUA N3 L5 I, NORTHEAST -1 ] POWELL PWX I N.O. ~ M 21 APS : PAGE GRAY MOUNTAIN WAUNETA SPIDER WEB ~~----s I G~ w~ s~ 532 BLACK MESA BM NAVAJO DEPOT ~ NAD I-----~- 532 WILLIAMS ~ M MC OODY MTN (EPNG) PARKS WMT WIX PK DAVENPORT DA J # MVA... <~-----t 230kV KACHINA I KA SEDONAL...rst-400- M MT -Y NEWMAN PARK DRK-WM ~ 490 SE ~ NP page NW-1 #4 M ~, i 167 MVA ) 532 IGARLAND GA PRARIE ~ 230kV WILLIAMS WM MUNDS PARK MP. WUPATKI WU OSBORNE TANK OT GLEN CANYON GCX HANKS HK FISH SAWMILL I ~~ I I FS 532 COCONINO CQ 90 0~ ELDEN 900~ WINSLOW page NE ,tm-,,:Of ELN SWITZER CANYON SZ SANDVIG SV 532

85 Page 85 of 149 I JEDITTO NTUA JDX il LEUPP.JCT. LJ WHITE CONE WCX INDIAN WELLS IWX TESIHAN TX h '------L---...L ,r-- DRYLAKE DK I, NORTHEAST- 2 ~ KEAMS CANYON 532--M I LEROUX KC LX HASHKNIFE CHOLLA HKF CH ~ ~ 1--_--11 DIABLO DB f il SUN~~INE I------il PADRE PE t------il WI~~NA 78 XFMR l BLUE RIDGE BR WINSLOW WS PIN~~~IFFS f----.l.- #2 100 MVA... <E:----i 230kV CT ~ 900 ABITIBI ACX HEBER #1 270 MVA ~<~ kV BCT-----' #1 50 MVA 230kV #8 143 MVA 345kV N.O. M I WOODRUFF WR T T I. I PIGLET PX CONLEY CLY I L...J IREIDHEAD RHD ~ ~ I 532 I. 532 X SHM N.O. 532 SHUMWAY SHOWLOW SL WAGON 450 WHEEL! 1 BCT'---+I--"I WGX 532 PINETOP LAKES PTX ST. JOHNS NEC N ~ 900 ~ COCONINO CQ DRU~E~EAT~I ~

86 Page 86 of PINE SPRINGS PS W~<fH M i ASHFORK M TOCK~ 252 AS WILLIAMS WM CHINO WELLS PF r~ NORTHWEST - 1 n WHITEHORSE LEBARRON WH LB ~ T T. M N.O. GREY to- 166 BEARS 7 XFMR , GBS 900 CROOKTON JCT. ~oo -----l CJT CHINO 5 ~3~ VALLEY 1 CV 500 CT M ~'84 : 5~,, EIGHT POLLOCK PAULDEN MILE PQ PU CREEK EMC I--r- CT - M,-M. 490~ COCONINO. I M N.O. l ~ CQ X N.O. 49' 0 ROGERS LAKE RG OLD HOME MANOR OHM 490=:r 1 9 DEWEY page NW-2 M t STURM RUGER SRG ' ANTELOPE AN 532 LONESOME --,--'---.-V ALLEY LY YAVAPAI YP #11 ~ 1 00MVA 230kV CHILDS pagtw N.O. I MINGUS 1 CEMENT CMX 532 x N.O. TAPCO TA WILLOW LAKE N.O. WL j GLASSFORD HILL GHT M-'---+-t #6 900 _:-- N.O. M~ M-LM ~ SUNDDG _~. '...~ 532~... BM 188 MVA N"~ 230kV 900 L SDG PRESCOTT 500 '----CT 532 ' ~ X --..I #10 I DELANO CITY 188 MVA. "".v DE '-----l4l-1- PC 3 I. ~9001 ~ WICKENBURG POPLAR WASH MORRISTOWN WB MARTINEZ STANTON YARNELL POP MQ ~9 I Y ~oo 1 MZW Njp. SN YA KIRKLAND JCT. X N.O. ~ 160~ ' KJ IBCRELAY C ~ C M M r M PC SWITCH 900 FLYING E X 187 RI J ON FLORES ~ WILHOIT WHITES PAR FE. N.O. RNC - FLR WQ WSP VERDE VE 600 PC SWITCH 900 N N

87 N W #3 100 MVA 230kV # MVA 230kV Attachment A Page 87 of 149 VERDE VE CEMENT CMX ~532 k:d--l YAVAPAI YP WILLOW LAKE WL cr I GLASSFORD HILL GHT POLAND JUNCTION PJ ::: ~~ N.O. X X N.O ~ COTTONWOOD ~ 11 OK 532 M I I I IOAK CREE~T ~~. 532 N.O. X 400 r M- CT. MUNDS PARK 532 MP MINGUS MS CAPITAL I 3 BUTTE CP SEDONA SE 532 BALD MOUNTAIN BMT ~532~ SOG ~ page NW-1 ---ll..-r...l..- DEWEY DW CORDES 532 CDS I C 5f 2 #2 270 MVA 500kV HAYFIELD HD 532~- 532 ORMES OM SYCAMORE SY QUAIL SPRINGS QS 900 3i CHILDS C NORTHWEST- 2 CORNVILLE CN MCGUIREVILLE MG STRAWBERRY STR T 500~ CT 3 CZ M M~ M- 326 r L CT 532 MAZATZAL MZT Y I ROCK SPRINGS -, RS #1 50MVA 345kV #6 100 MVA 345kV PREACHER CANYON PR n TONTO TT 800 BCT---...J 900

88 Page 88 of 149 SADDLE BROOKE RANCH SBK FARRELL HIDDEN VALLEY WINGFIELD CAYWOOD FR HV 69KV WF CWO ~ ~ ~ X N.O. SEXTON L ~ ~ SX r--- TOLTEC~ 658 TLT SAN MANUEL SM ARICA~ XVMR ARC ~ 900 TO t CASAGRANDE I, SOUTHEAST - 1 n 500 BCT 900 MARICOPA (DOE) MAX VISTA VS ~ 900 ASARCO PIT AX 326~ PAPAGO ~ PG ~TTX 1600~ FR 1600~ TALX 1600~ SDNX 730 MINE 800 BCT #4 725 MVA '-;:"""- I 500kV 3 L;J~ 300~ SR 230KV ~ CASAGRANDE ED-4 (DOE)CGX N ~ 14 L...I DEL BAC DBX TUCSON I r.l. (DOE) ~815 TUX 600 SWITCH ORACLE VALLEY FARMS 798 JUNCTION ;ro VF OJX kV H t ~502 J: COOLIDGE ADAMS CLX RAWLE AM r-1 BOOTHILL SNAKE BCT 395 BH MD O M M ~ 115kV APACHE NOGALES APX NOX #7 725 MVA 500kV ED-2 M M I TO TATMOMLI I ED-5 ELOY (DOE) ELX HAYES lr"3t-326 GULCH~ HC 5 L...I PINAL SRP PZX SAN 200 MURAL DON LUIS PEDRO M- BCT--{D1 McNEAL MU DL SPD 550 NO MN 251 ~184~ PALOMINAS FAIRVIEW ' XFMR 400 PAL FA BCT , # MVA 69kV 69kV 12.47kV

89 Page 89 of 149 PARKER DOE PAX HAVASU CAP L --.-_'--_ 240 (DOE) I MECO COLORADO CR BILL PLANET PN WILLIAMS BWX WELLFIELD WFX APS OLD BAGDAD TOWNSITE 12kV i ; SOUTHWEST - 1 ~ BAGDAD ----r r r- -i WILLOW LAKE ~... ~ WL BAX r7l Inl 2 11SkV II I I \V BIA1APS BLUEWATER. ~ BW ' APS I SCE 34.SkV T N 0 I WHIPPLE! ' - x. "> PEDDLER : 1 I. I LINE 25 MVA I CROSSROADS CRS I-----r-->~ POSTON 532 I N.O r 161kV PARKER~ X ~ N.O. HAVASU HU QUARTZSITE QZ 61kV DO:1 APS #3 BLACK PEAK 35 MVA BP COPPERSTONE WELLS CSW 184~ V N:r 'O. Vi ' j EAGLE, EYE EE UTTING UT VICKSBURG VB SALOME SA COPPERSTONE MINE CSM N UI

90 Page 90 of 149 YCAX ~ 900 [H, - SOUTHWEST - 2 n YUCCA YU RIVERSIDE RVS 900 YUMA PALMS NORTH GILA QUECHAN YMT NG p..!J ~ 900 T 1000 rs--r KINDER MORGAN ~ KM MITTRY 1600 MT #4 I----.;~~ 240 MVA 500kV 900 #4 APS I... I.. #2 lid 7S.6MVA5 7SMVA 161kV ~ 161kV 800 ~ 1200 CT 1600 N.OJ PILOT KNOB M i PKX J ND ST. TH BAJA. LA~gNA, I ~ SWITCH 1600 I I SANGUINETTI SGT 1600 ~ FOOTHILLS REDONDO RE I N.O. MARINE AIR BASE MA 900 FH SWITCH ARABY AR EJ-t SENATOR WASH SWX 900 II GILA GIX #1 > 240MVA 500kV 1200 N 0) u5: 5:2 SAN LUIS SNL 20 MVA SONORA I,..., "r' ~.5kV SRX CFE 1-t- 326~ 400 MtIM----EijHB WAPA _ 25MVA APS 34.5kV 34.SkV YCWU MEXICO LOAD.

91 Page 91 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN TECHNICAL STUDY REPORT FOR THE ARIZONA CORPORATION COMMISSION JANUARY 2012 Bl

92 Page 92 of 149 Executive Summary Pursuant to North American Electric Reliability Corporation ("NERC") Standard TPL-001 "System Performance Under Normal (No Contingency) Conditions (Category A)", Arizona Public Service Company ("APS") performs annually a Category A analysis. The Category A analysis is performed for system conditions listed in Table I of the NERC/WECC Planning standards. Results of the study indicate that, with the projects identified in APS's Ten-Year smission System Plan, APS is fully compliant with NERC Standard TPL-OO 1. Pursuant to NERC Standard TPL-002 "System Performance Following Loss of a Single Bulk Electric System Element (Category B)", APS performs annually a Category B contingency analysis. In Table I of the NERC/WECC planning standards, there are a total of four different Category B events that are to be studied each year to meet NERC Standard TPL-002. A comprehensive list of contingencies was developed for the Category B contingency analysis and performed for the system conditions listed in Table I of the NERC/WECC Planning standards based on engineering judgment. APS believes that the selection of contingencies for inclusion in these studies, which is based on Category B of Table I of the NERC/WECC Planning standards, is acceptable to WECC. If requested by WECC, APS will implement measures to correct any deficiencies that have been identified by WECC. Results of the study indicate that, with the projects identified in APS's Ten-Year smission System Plan, APS is fully compliant with NERC Standard TPL-002.

93 Page 93 of 149 Table of Contents I. Introduction... 1 II. Base Case Development... 1 III. Power Flow Analyses IV. Stability Analyses... 6 V. Category A & B Contingency Study Results... 6 Appendices A. Representative Contingency List A1-A12 B. Power Flow Maps... B1-B9 C Stability Plots C1-C12 D Stability Plots... D1-D13 11

94 Page 94 of 149 ARIZONA PUBLIC SERVICE COMPANY TEN-YEAR TRANSMISSION SYSTEM PLAN TECHNICAL STUDY REPORT I. Introduction This technical study report is performed and filed annually with the Arizona Corporation Commission ("Commission") pursuant to ARS and Decision No (July 25,2001). This report summarizes the results of power flow analyses and stability analyses for the Arizona Public Service Company ("APS") transmission system. Power flow analyses were conducted for every year within the ten year planning window ( ) and performed for two scenarios: (i) assumption that all transmission system elements are in service and within continuous ratings (Category A); and (ii) assumption of an outage on a single element, with all remaining system elements remaining within emergency ratings (Category B). Voltage deviations for these scenarios must also be within established guidelines. These voltage deviation guidelines closely approximate post-transient Volt Ampere Reactive ("VAR") margin requirements of the Western Electricity Coordinating Council ("WECC"). More detail is provided in APS's smission Planning Process and Guidelines, which is also included in the annual APS Ten-Year smission System Plan ("Ten-Year Plan") filing. The stability analyses were performed to simulate electrical disturbances on the transmission system and evaluate the system response. The desired result is that all generators will remain on line, no additional lines will open, and the system oscillations will damp out. Results of the power flow and stability analyses aid in determining when and where new electrical facilities are needed because of reliability or security reasons. Additionally, some facilities are planned to address adequacy concerns. These include the interconnection of generation to the transmission system or efforts to increase import capability and/or export/scheduling capability to load-constrained or other areas. II. Base Case Development Power flow cases were created for each year of the study time frame. These cases were developed from the latest available WECC heavy summer power flow cases. The 2014 CATS heavy summer case was chosen as the first bulk seed case. This case was developed from a 2014 WECC heavy summer base case. The CATS case was then updated in a coordinated effort between Arizona utilities to include the subtransmission and distribution models. This case was used as the seed case in the creation of the power flow cases used for the power flow analyses performed for the Ten-Year plan. Each intermediate case developed was updated with the forecasted loads and any system additions/upgrades that are planned in the respective

95 Page 95 of 149 year. The forecasted loads modeled within the cases utilized inherently include the effects of distributed renewable generation as well as energy efficiency programs. The second and final seed case chosen was the 2021 Heavy summer power flow case that was developed through the CATS sub-committee of SWAT. In a collaborative effort, the Arizona utilities used the jointly developed 2021 CATS case to develop a 2021 summer case that included the sub-transmission and distribution systems of the Arizona utilities. This seed case was used to develop the power flow cases. Each intermediate case developed was updated with the forecasted loads and any system additions/upgrades that are planned in the respective year. The forecasted loads modeled within the cases utilized inherently include the effects of distributed renewable generation as well as energy efficiency programs. These cases represent the latest transmission and sub-transmission plans, load projections, and resource plans of utilities and independent power producers. By utilizing WECC base cases, all loads, resources, firm power transfers, and planned projects within the WECC system are represented. By using jointly developed seed cases the most accurate Arizona system is represented. 2

96 Page 96 of 149 III. Power Flow Analyses Base case and single contingency conditions are evaluated to determine system needs and timing. Various iterations of possible solutions lead to the final plans for transmission additions. The contingency analysis involves simulations for every nonradial 115kV or above line that APS owns, partially owns, or operates. sformer as well as generator outages are also evaluated. The APS system includes several reactive power resources that are used to maintain bus voltages within the limits defined by The smission Planning Process & Guidelines. These reactive power resources include shunt devices, series compensation, and tap changing transformers. The reactive power resources are adequate and meet the system performance. APS does not have any existing or planned control devices. These devices exist outside the APS control area; however, they are not utilized or their operation is not necessary as a result of the contingencies in this study. No planned outage of bulk electric equipment at APS occurs during the heavy summer peak time. Therefore it is not necessary to study planned outages since this Ten Year Plan study focuses on the heavy summer peak time. Results of the power flow studies are tabulated in a Security Needs Table and an Adequacy Needs Table, below. These tables identify 14 transmission projects that are included in this Ten-Year Plan filing. Some of the projects were classified as Adequacy Needs because of the uncertainty of generation location, project size, and transmission availability in the later years. As projects near the five-year planning time frame, they may be redefined as Security Needs projects. For the projects included in the Security Needs Table, selected maps of the power flow simulations are contained in Appendix B showing the pre-project scenario (outage and resulting violation) and the post-project scenario (outage and no criteria violations). 3

97 Page 97 of 149 smission Project Youngs Canyon (Flagstaff) 345/69kV interconnection Mazatzal 345kV substation Trilby Wash (TS1) 230kV substation In Service Year Table 1: Security Needs Table Critical Outage Limiting Element/Condition Map 230/69kV Voltage deviations on the sub- B5-B6 transformers at transmission system in the area Coconino resulting in load shedding Preacher Canyon - Voltage deviations on the sub- B7 Tonto 69kV line transmission system in the area resulting in load shedding Preacher Canyon - Voltage deviations on the sub- B8-B9 Owens 69kV line transmission system in the area resulting in load shedding Westwing 230/69kV Overloads remaining Westwing B1-B2 sformer 230/69kV sformer McMicken-Westwing Overloads McMicken-Surprise 69kV B3-B4 69kV line. line 4

98 Page 98 of 149 smission Project Palo Verde-Delany Desert Basin-Pinal Central 230kV line and Pinal Central- Sundance 230kV line Palo Verde Hub to North Gila 500kV #2 line. North Gila-TS8 230kV line. Delany-Sun Valley 500kV line & Sun Valley-Trilby Wash 230kV line Palm Valley-TS2- Trilby Wash 230kV line Sun Valley-Morgan 500kV line. Saguaro (TS 12): Relocate the 230kV yard and install a 230/69kV sformer T a bi e 2. Ad equacy N ee d s T a bi e In Service System Benefits Year 2013 Increases the export scheduling capability from the Palo Verde ("PV") area to provide access to both solar and gas resources. The project is also to provide for the interconnection of 3 solar generation projects into the Delany switchyard Increases the reliability of the Sundance generating facility and provides an APS transmission path for delivery of the full output of the Sundance generating facility. Provides another transmission path in the regional system, thereby increasing the system reliability and capacity in order to continue to serve the growing electrical demand in an economical and reliable manner Increases import capability for the Yuma area and export/scheduling capability from the PV area to provide access to both solar and gas resources. Increases transmission system reliability and ability to deliver power from these resources. Increases transmission system reliability Increases transmission system reliability and ability to distribute and deliver power within the Yuma area Increases the import capability for the Phoenix Metropolitan area and export/scheduling capability from the PV area to provide access to both solar and gas resources. Increases the system reliability by providing a new transmission source to help serve the growing areas in the western portions of the Phoenix Metropolitan area Provides a second 230kV source for Trilby Wash so that it is not served as a radial substation, thereby increasing the local system reliability. Also, connecting the Sun Valley-Trilby Wash 230kV line to Palm Valley also increases the reliability of the high voltage transmission system on the western side of the Phoenix Metropolitan area Increases import capability for the Phoenix Metropolitan area and export/scheduling capability from the PV area which includes both solar and gas resources. Increases transmission system reliability and ability to deliver power from these resources. Provides a second 500kV source for the Sun Valley substation. Provides support for multiple Category C and D transmission contingencies This project is needed to provide electric energy in the northern portions of the Phoenix Metropolitan area as well as increase the reliability and continuity of service for these areas. 5

99 Page 99 of 149 IV. Stability Analyses A stability simulation for simulated three-phase faults was performed for 2014 and 2021 for every non-radial 115kV, 230kV, 345kV or 500kV line that APS owns (totally or partially) or operates. It has been APS's experience that stability concerns do not manifest on the sub-transmission system, which is primarily designed to deliver power to load. Therefore, no simulations were performed at voltage levels less than 115kV, except at generator substation. Additionally, every new proposed generation plant will be required to perform stability evaluations prior to receiving permission to interconnect to the transmission system. Existing and planned protection systems are utilized in the study, including any backup or redundant system, and represent fault clearing times, the operation of the protection system, andthe resulting removal of the facility that would occur as a result of the simulated event. Each simulation modeled a 3-phase bus fault, appropriate series capacitor flashing and reinsertion, fault removal, and transmission line removal. System performance was evaluated by monitoring representative generator rotor angles, bus voltages and system frequency. Plots of these system parameters are included in Appendices C and D. The stability simulations performed to date indicate that no stability problems limit the transmission system V. Category A & B Contingency Study Results A high level overview of the results for the Category A and Category B contingences is shown in Table 3. From this table, it is shown that each of the Category A and Category B contingencies meets the NERCIWECC Planning Standards.. T a bl e 3 : 0 vervlew 0 fc a t egory A &B St an d ar d R esu It s 1-5 year Time Frame 6-10 year Time Frame Standards Case Years Standards NERC Planning Standards Category A Case Years Studied Met? Studied Met? All Facilities in Service 2012 through 2016 Yes 2017 through 2021 Yes 1-5 year Time Frame 6-10 year Time Frame Standards Case Years Standards NERC Planning Standards Category B Case Years Studied Met? Studied Met? 3-Phase Fault with Normal Clearing- erator 2012 through 2016 Yes 2017 through 2021 Yes 3-Phase Fault with Normal Clearing - smission Circuit 2012 through 2016 Yes 2017 through 2021 Yes 3-Phase Fault with Normal Clearing - sformer 2012 through 2016 Yes 2017 through 2021 Yes Loss of an Element Without a Fault 2012 through 2016 Yes 2017 through 2021 Yes Table 3 is a high level summary that shows, with the projects listed in Tables I & 2, the APS system meets the criteria listed in NERC Standards TPL-OOI and TPL-002. The transient stability plots are detailed in Appendices C & D. Due to the size of the power flow thermal and voltage steady state analysis the detailed results are not included. However, they are available upon request by WECC or any other authorized stakeholder. 6