Feasibility Study. Customer Kingman Area Photovoltaic Generation Project Interconnection

Transcription

1 Feasibility Study Customer Kingman Area Photovoltaic Generation Project Interconnection October, 2009 October 2009 i

2 EXECUTIVE SUMMARY CONCLUSION Customer has requested network resource interconnection service from UNS Electric (UNSE) to integrate its proposed Kingman area photovoltaic generation project (KAPVGP or Project) to the UNSE 69 kv transmission system located in the vicinity of Kingman and Golden Valley in Mohave County, Arizona. The project would provide up to 150 MW of photovoltaic resource generation with in-service date of May The project would consist of one to three units of 50 MW each. The Customer and the UNSE have discussed three options of interconnecting the project. These interconnecting options are via: A 69 kv radial line to the UNSE s Industrial 69 kv Substation, $885k. A 69 kv radial line to the UNSE s Boriana Junction 69 kv Substation, $8,755k. A 69 kv radial line to the UNSE s West Golden Valley 69 kv Substation, $9,055k. All three of the above, $10,405k Estimates provided by UNSE/TEP Substation Engineering include all representative direct costs and overheads, but do not include any income tax gross-up that may be required to be collected. Any tax gross-ups will be calculated, collected and refunded in accordance with UNS Electric s Rules & Regulations.. The cost estimates are nonbinding and do not include mitigation of issues on other affected systems. The study evaluated a single 50 MW plant operating alone and all three plants operating concurrently at each of the three locations. Based on the feasibility analysis which evaluated the steady-state response of the UNSE transmission system to the proposed project subject to normal (N-0), single (N-1) as well as multiple (N-2) contingencies, each of the three interconnection options were found to be technically capable of interconnecting the proposed generation additions to the UNSE 69 kv system with appropriate interconnection and mitigation facilities in-place. From the short circuit analysis, performed by UNSE/TEP Protection group, there appear to be no post-project conditions that appreciably increase fault duty beyond the interrupting capability of existing fault interrupting devices on the 69 kv systems out of Griffith or Hilltop substations. The Industrial 69 kv interconnection option was found to be the lowest cost among the alternatives studied. No transmission facility overload was identified under normal as well as contingency conditions following the interconnection of the proposed 50 MW generating plant at Industrial 69 kv substation. The other alternatives however would require an additional 230/69 kv transformer at Griffith station and addition of approximately six miles of new 69 kv circuit between Griffith and the vicinity of Boriana Junction. In the case of plants at Boriana Junction, West Golden Valley or both, a 69 kv switching station near Boriana Junction would also be required to provide adequate protection coordination with the Black Mountain Generating Station. October 2009 ii

3 BACKGROUND UNSE elected a third party contractor, PDS Consulting, PLC (PDS) to perform the interconnection feasibility study for the KAPVGP project. The analysis was performed using WECC approved 2012 heavy summer and 2013 light winter base cases provided by the UNSE. The scope of the analysis was to: Identify the feasibility of interconnecting the KAPVGP project as individual points of interconnection for 50 MW generating plants in the Kingman and Golden Valley area at each of the three locations and as a three 50 MW plants operating concurrently at the three locations. Identify the transmission system impacts caused solely by the addition of the KAPVGP project for normal operating conditions (N-0) as well as single (N-1) and multiple (N-2) contingencies. Studies performed included power flow and short circuit analysis. Transient stability analysis will be conducted in the System Impact Study phase if the Customer elects to continue the interconnection process. The studies described in this report demonstrated the feasibility of interconnecting each of the three 50 MW plants in the KAPVGP to the UNSE transmission system via: A 69 kv radial line to the UNSE s Industrial 69 kv Substation. A 69 kv radial line to the UNSE s Boriana Junction 69 kv Substation. A 69 kv radial line to the UNSE s West Golden Valley 69 kv Substation. The study indicates that the addition of the KAPVGP and the subsequent schedule of its output to the Palo Verde generation hub will not cause any new transmission facility overloads under normal or contingency operating conditions if the project is connected to the UNSE s Industrial 69 kv substation. However, if the project is connected to the UNSE Boriana Junction 69 kv substation, a second 80 MVA 230/69 kv transformer would be required at Griffith. Additionally, a new 69 kv circuit would have to be built to reduce the complexity of relay coordination involving other generation on the existing 69 kv system out of Griffith substation. Interconnection to the UNSE s West Golden Valley or Boriana Junction 69 kv substations would also trigger the need for an additional 80 MVA 230/69 kv transformer at Griffith. Interconnection of the proposed project at Boriana Junction, West Golden Valley or both, would also require the installation of a 69 kv switching station in the vicinity of Boriana Junction to further improve reliability and relay coordination out of Griffith substation to accommodate the Black Mountain Generating Station. The study also indicated that the addition of the KAPVGP caused up to three 230 kv transmission line to overload following multiple outages. There were also several existing transmission facility overloads exacerbated by the addition of the project. To mitigate the identified overloads under multiple outages the project may be required to participate in existing operational procedures or may be included in a new operational procedure. Detailed analysis of impacts to the overlying HV and EHV October 2009 iii

4 transmission system will involve Western Area Power Administration and will be dealt with in the System Impact Study phase. The power flow analysis prior to the interconnection of the KAPVGP did not indicate any transmission facility overloads under normal operating conditions. The study however found six transmission facility overloads under single element outages and two 230 kv transmission line overloads following multiple outages. October 2009 iv

5 CONTENTS Introduction... 1 Project and Interconnection Information... 1 Study Base Case Description and Assumptions... 3 Study Methodology and Evaluation Criteria...4 Study Results....5 Mitigation Plan Cost Estimating Appendix A: Power Flow Maps...18 Appendix B: Summary of Power Flow Study Results Appendix C: Power Flow Contingency List...43 Appendix D: Single-line Diagrams...51 Appendix E: Cost Estimating...55 October 2009 v

6 INTRODUCTION Customer has requested network resource interconnection service from UNS Electric (UNSE) to integrate its proposed Kingman area photovoltaic generation project (KAPVGP or Project) to the UNSE 69 kv transmission system located in the vicinity of Kingman and Golden Valley in Mohave County, Arizona. The project would provide up to 150 MW of photovoltaic resource generation with in-service date of May The project would consist of up to three units of 50 MW each. The Customer and the UNSE have discussed three options of interconnecting the project. These interconnecting options are via: A 69 kv radial line to the UNSE s Industrial 69 kv Substation. A 69 kv radial line to the UNSE s Boriana Junction 69 kv Substation. A 69 kv radial line to the UNSE s West Golden Valley 69 kv Substation. This study evaluated a single 50 MW plant operating alone and all three plants operating concurrently at each of the three locations. UNSE elected a third party contractor, PDS Consulting, PLC (PDS) to perform the interconnection feasibility study for the KAPVGP project. Only power flow analysis was performed. The analysis was performed using WECC approved 2012 heavy summer and 2013 light winter base cases provided by the UNSE. The scope of the analysis was to: Identify the feasibility of interconnecting the KAPVGP project as a single 50 MW plant in the Kingman area at each of the three locations and as three 50 MW plants operating concurrently at the three locations. Identify the transmission system impacts caused solely by the addition of the KAPVGP project for normal operating conditions (N-0) as well as single (N-1) and multiple (N-2) contingencies. PROJECT AND INTERCONNECTION INFORMATION Table 1 provides the general project and interconnection information about the KAPVGP. Project Location Mohave County, Arizona Type of Generation Resource Photovoltaic generating plant Maximum Generator Output 50 MW per plant, 150 MW net project size Power Factor Unity Step-up Transformer (s) Three (3), 30/40/50 MVA, 35/69 kv transformer, Z=7.5% Interconnection Configuration See Figure 1 & 2. Interconnection Voltage 69 kv Table 1: The KAPVGP Project General Information October

7 Figure 1 depicts the KAPVGP Project interconnection options and the existing transmission system at the interconnection vicinity. A one-line diagram of the basic KAPVGP layout is shown in Figure 2. to WATERFIELD 50 MW PV W GOLDEN VALLEY to JAGERSON 50 MW PV INDUSTRIAL to ARCO BREAKER (NO) to CASSON EASTERN NO to BOUNDARY CONE 50 MW PV BORIANA JCT 352 HILLTOP 69 kv GRIFFITH 69 kv SACRAMENTO BLACK MOUNTAIN YUCCA Figure 1: The KAPVGP Project Interconnection Options 69 kv Bus 34.5 kv Bus 480 V Bus 500 kw PV Sub-array 480 V Bus Distribution Bus kw PV Sub-array Figure 2: Typical One-Line Diagram of the KAPVGP 50 MW Plant October

8 STUDY BASE CASE DESCRIPTION AND ASSUMPTIONS This analysis was conducted using two power flow base cases: Western Electricity Coordination Council (WECC) approved 2012 heavy summer (12hs2a.sav) and 2013 light winter (13lw1s.sav) base cases. The 2012 heavy summer base case was adjusted to reflect 2011 heavy summer forecasted operating conditions in the study area. The 2013 light winter case was modified to reflect forecasted UNSE s lowest daytime peak conditions in winter of Generation dispatch modeled in the WECC base cases was not modified. The benchmark (pre-project) base cases were tested to ensure that all transmission facilities in the study area are within their normal operating limits. While it is impossible to study all combinations of system load and generation levels during all seasons, these two pre-project base cases represent extreme loading and generation conditions for the study area. However, UNSE cannot guarantee that the KAPVGP can operate at maximum rated output year round without impacting the transmission system during times and seasons not studied. Four post-project base cases were developed from each of the pre-project cases. The post-project base cases modeled the proposed KAPVGP for the interconnections depicted in Figure 1. The output of KAPVGP project was dispatched to replace merchant generators at Palo Verde/Hassayampa generation hub for this study. Table 2 provides descriptions of all the pre- and post-project base cases developed for the feasibility study. Pre- /Post- Base Case Description Base Cases Pre-project Case A Approved WECC 2012 Heavy summer pre-project base case. Models 2011 forecasted load in the study area. Pre-project Case B Approved WECC 2013 light winter pre-project base case. Models 2011 forecasted load in the study area. Post-project Case A1 Developed from Pre-project Case A and models the 50 MW KAPVGP project connected to UNSE s Industrial 69 kv substation. Post-project Case A2 Developed from Pre-project Case A and models the 50 MW KAPVGP project connected to UNSE s Boriana 69 kv substation. Developed from Pre-project Case A and models the 50 MW KAPVGP project Post-project Case A3 connected to UNSE s W. Golden Valley 69 kv substation. Developed from Pre-project Case A and models the 150 MW KAPVGP project Post-project Case A4 distributed equally at UNSE s Industrial, Boriana and W. Golden Valley 69 kv substations. Developed from Pre-project Case B and models the 50 MW KAPVGP project Post-project Case B1 connected to UNSE s Industrial 69 kv substation. Developed from Pre-project Case B and models the 50 MW KAPVGP project Post-project Case B2 connected to UNSE s Boriana 69 kv substation. Post-project Case B3 Developed from Pre-project Case B and models the 50 MW KAPVGP project Post-project Case B4 connected to UNSE s W. Golden Valley 69 kv substation. Developed from Pre-project Case B and models the 150 MW KAPVGP project distributed equally at UNSE s Industrial, Boriana and W. Golden Valley 69 kv substations. Table 2: Pre-/Post-project Base Cases October

9 STUDY METHODOLOGY AND EVALUATION CRITERIA Power flow analysis was performed on both the pre-project and post-project cases to determine the impact of the KAPVGP Project on the UNSE sub-transmission system and the interconnected facilities within the study area. Specific studies conducted and their evaluation criteria are outlined below: Power Flow Analysis Power flow analysis was performed on both the pre-project and post-project base cases detailed in Table 2. The base cases were used to simulate the impact of the Project during normal operating conditions (N-0) as well as single (N-1) and multiple contingency conditions. The contingencies simulated included: All single sub-transmission and transmission circuit outages within the study area (N-1). All single transformer outages within the study, excluding transformers serving only distribution load (N-1). All Tie Lines to adjacent connecting immediately outside the study area (N-1). All pairs of the above single outages (N-2) The WECC/NERC and UNSE planning standards will be used to assess the adequacy of the study results. The power flow analysis related evaluation criteria that will be used are summarized below: Pre-contingency bus voltage outside the study area must be between 0.95 per unit and 1.05 per unit. Post-contingency 69 kv voltages must be between 0.95 and 1.05 per unit. Study area transmission voltages >1.00 pu. Fictitious buses to model transformer terminated lines are not subject to this criterion. Pre-contingency UNSE 69 kv bus voltages between 0.95 and pu Maximum voltage deviation allowed at all buses under contingency conditions will be 5% for all contingencies. Pre-disturbance loading to remain within continuous ratings of all equipment and line conductors Post-disturbance loading to remain within emergency ratings of all equipment and line conductors. Post-project representation of the KAPVGP maintained unity power factor at the plant's point of interconnection to the UNSE system October

10 Short Circuit Analysis Short circuit studies were performed to evaluate the impact of the addition of the KAPVGP on selected UNSE-Mohave substation breaker duties. STUDY RESULTS Pre-Project Power Flow Analysis Results Power flow analysis was performed on both the 2012 heavy summer and 2013 light winter base cases. Power flow maps for both base cases can be found in Appendix A. Key findings from the power flow analysis using both the heavy summer and light winter pre-project base cases are: No transmission facility overload was identified under normal operating conditions prior to the addition of KAPVGP. Six (6) transmission facility overloads were identified following selected single element (N-1) outages. Two (2) 230 kv transmission lines were found to be overloaded under multiple outages during the summer operating condition. (See Appendix B, Table B1 for the identified overloads) No bus voltage deviation violation was identified. Industrial 69 kv Interconnection Power Flow Analysis Results a) 2012 Heavy Summer Base Case Power flow Maps for 2012 heavy summer post-project base case A1 developed for the Industrial 69 kv interconnection can be found at Appendix A. Difference power flow maps between the pre- and post-project base case A1 can also be found at Appendix A. Power flow solutions were achieved for all the outages simulated. Appendix B, Table B1 provides a summary of the results of the power flow analysis. Key findings from the power flow studies using the 2012 heavy summer base cases are: No transmission facility overload was identified under normal operating condition following the interconnection of the KAPVGP to the Industrial 69 kv substation. No transmission facility overload attributable to the project was identified under N-1 contingency conditions. No transmission facility overload solely due the proposed project following multiple outages. However, two existing 230 kv transmission line contingency overloads were exacerbated following the addition of the KAPVGP. (See Appendix B, Table B1 for the identified overloads) No bus voltage deviation violation was identified. October

11 b) 2013 Light Winter Base Case Summary of the results of the pre- project base and post-project base case A1 can be found at Appendix B, Table B2. Power flow Maps for 2012 light winter pre- and postproject base cases can also be found at Appendix A. Key findings from the power flow studies are: No transmission facility overload was identified under normal operating condition following the interconnection of the KAPVGP to the Industrial 69 kv substation. No transmission facility overload solely due to the project under N-1 or N-2 contingency conditions. No bus voltage deviation violation was identified. Boriana Junction 69 kv Interconnection Power Flow Analysis Results a) 2012 Heavy Summer Base Case Power flow Maps for both 2012 heavy summer pre- and post-project base case A2 can be found at Appendix A. Difference power flow maps can also be found at Appendix A. Power flow solutions were achieved for all the outages simulated. Appendix B, Table B3 provides a summary of the results of the power flow analysis. Key findings from the power flow studies are: Two (2) new transmission facility overloads attributable to the KAPVGP project were identified under normal (N-0) operating condition. The GRIFFITH 230/69 kv transformer loaded up to 122% of the transformer s normal rating following the interconnection of the project to Boriana 69 kv substation. Also the BORIANA-BORIANA TAP 69 kv line loaded up to 103% of the line s normal rating. Two (2) new transmission facility overloads identified following selected N-1 outages. See Table 5 for the identified transmission facility overloads. Two (2) new 230 kv transmission lines were overloaded following multiple outages. Also two existing 230 kv transmission line contingency overloads were exacerbated following the addition of the KAPVGP. (See Appendix B, Table B3 for the identified overloads) No bus voltage deviation violation was identified. b) 2013 Light Winter Base Case Summary of the results of the pre- project base and post-project base case A2 can be found at Appendix B, Table B4. Power flow Maps for 2012 light winter pre- and postproject base cases can also be found at Appendix A. Key findings from the power flow studies are: October

12 Two (2) new transmission facility overloads attributable to the KAPVGP project were identified under normal operating condition. The GRIFFITH 230/69 kv transformer loaded up to 163% of the transformer s normal rating following the interconnection of the project to Boriana 69 kv substation. Also the BORIANA- BORIANA TAP 69 kv line loaded up to 105% of the line s normal rating. Two (2) new transmission facility overloads identified following selected N-1 outages. See Table 5 for the identified transmission facility overloads. No bus voltage deviation violation was identified. W. Golden Valley 69 kv Interconnection Power Flow Analysis Results a) 2012 Heavy Summer Base Case Power flow Maps for both 2012 heavy summer pre- and post-project base case A3 developed for the W. Golden Valley 69 kv interconnection can be found at Appendix A. Difference power flow maps can also be found at Appendix A. Power flow solutions were achieved for all the outages simulated. Appendix B, Table B5 provides a summary of the results of the power flow analysis. Key findings from the power flow studies are: One (1) new transmission facility overload was identified under normal operating condition. The GRIFFITH 230/69 kv transformer loaded up to 121% of the transformer s normal rating following the interconnection of the project to W. Golden Valley 69 kv substation. Two (2) new transmission facility overloads were identified under N-1 contingency conditions. See Table 5 for the identified transmission facility overloads. Two (2) new 230 kv transmission line was overloaded following multiple outages. Two existing 230 kv transmission line contingency overloads were exacerbated following the addition of the KAPVGP. (See Appendix B, Table B5 for the identified overloads) No bus voltage deviation violation was identified. b) 2013 Light Winter Base Case The power flow results using 2013 light winter base cases were similar to the results obtained during heavy summer operating conditions. The results are summarized in Table B6, Appendix B. Power flow Maps are provided in Appendix A. Key findings from the power flow studies are: One (1) new transmission facility overload was identified under normal operating condition. The GRIFFITH 230/69 kv transformer loaded up to 162% of the transformer s normal rating following the interconnection of the project to W. Golden Valley 69 kv substation. Two (2) new transmission facility overloads were identified under N-1 contingency conditions. See Table 5 for the identified transmission facility October

13 overloads. No bus voltage deviation violation was identified. All 3 69 kv Substation Locations Power Flow Analysis Results a) 2012 Heavy Summer Base Case Key findings from the power flow studies provided in Appendix B, Table B7 are: Two (2) new transmission facility overloads attributable to the KAPVGP project were identified under normal operating condition. The GRIFFITH 230/69 kv transformer loaded up to 185% of the transformer s normal rating and the BORIANA-BORIANA TAP 69 kv line loaded up to 105% of the line s normal rating. Two (2) new transmission facility overloads identified following selected N-1 outages. See Table 5 for the identified transmission facility overloads. Three (2) new 230 kv transmission line was overloaded following multiple outages. Two existing 230 kv transmission line contingency overloads were exacerbated following the addition of the KAPVGP. (See Appendix B, Table B7 for the identified overloads) No bus voltage deviation violation was identified. b) 2013 Light Winter Base Case Summary of the results of the pre- project base and post-project base case A4 can be found at Appendix B, Table B8. Power flow Maps for 2012 light winter pre- and postproject base cases can also be found at Appendix A. Key findings from the power flow studies are: Two (2) new transmission facility overloads attributable to the KAPVGP project were identified under normal operating condition. The GRIFFITH 230/69 kv transformer loaded up to 227% of the transformer s normal rating and the BORIANA-BORIANA TAP 69 kv line loaded up to 107% of the line s normal rating. Two (2) new transmission facility overloads identified following selected N-1 outages. See Table 5 for the identified transmission facility overloads. No bus voltage deviation violation was identified. October

14 Short Circuit Analysis To perform the short circuit study, the 50 MW photovoltaic generation additions were modeled in the TEP short circuit base case using the ASPEN One-Liner software. This case originated from the post-project for the proposed Bowie Power Station project. The following data was used to prepare the short circuit case: 1. ASSUMED PV INVERTERS ARE A CONSTANT SOURCE = LOAD CURRENT 2. ASSUME 50 PAD MOUNT TRANSFORMERS FOR TOTAL GEN= 50MW PV EQ 0.265kV 0.0P P-90 50MWPV INVERTER X''d= 1.0 ( EQUIV. SUBTRANSIENT REACTANCE) S= 50MVA PV MV PV HV 50 TRANSFORMERS-- 35.kV 69.kV PAD MOUNT TRANSFORMER 0.0P P-75 EQUIVALENT 50 MVA Z EQ= 7.5%/50 = 0.15%, X/R= 5.48 INTERTIE TRANSFORMER S= 50 MVA Z= 7 % ASSUME X/R= P P P P P-90 BORIANA, INDUSTRIAL 3- PHASE FAULT WEST GOLDEN VALLEY INTERCONNETS Table 3 summarizes the short circuit magnitude for three-phase and single-line-toground faults for the pre-project and post-project conditions. Fault duty data in Table 3 is sorted from the highest incremental three-phase current at the Point of Interconnection (POI) to the lowest in order of magnitude for the regional buses. There appear to be no post-project conditions that appreciably increase fault duty beyond the pre-project values. Mitigation of any fault duty in excess of circuit breaker interrupting capability pre-project may cover mitigation of these issues post-project. The available margin at the regional buses was not available at the time of this report; however, it is expected that due to the magnitude of the incremental fault duty and the relatively new age of the breakers with higher interrupting capability in this region that the interconnection of the BPGS CSP may not require mitigation of any breakers. October

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19 MITIGATION PLANS Provided in Table 5 below are the recommended corrective mitigation plans for the identified transmission facility overload solely due to the addition of the KAPVGP. For any existing overloads exacerbated with the addition of the KAPVGP, the project could be included in the existing mitigation plan or be made to participate in any new mitigation plan designed for such an overload. Outage Overloaded Facility Rating Overload Recommended Mitigation Industrial 69 kv Interconnection N-0 ALL LINES IN SERVICE None N/A N/A None N-1 None None N/A N/A None Boriana Junction 69 kv Interconnection N-0 80 MVA 163% Add second 80 MW, 230/69 kv transformer ALL LINES IN SERVICE GRIFFITH 230/69 kv transformer BORIANA BORIANATP 69 KV LINE 368 A 105% Bypass overloaded segment by constructing new 69 kv circuit between Griffith and a 69 kv switching station in the vicinity of Boriana Junction (see Appendix D1 & D2) N-1 BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE 912 A 119% Bypass overloaded segment by GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A 118% constructing new 69 kv circuit between Griffith and a 69 kv switching station in the vicinity of Boriana Junction (see Appendix D1 & D2) Table 5: Overloaded transmission facilities and associated recommended mitigation plans October

20 Outage Overloaded Facility Rating Overload (%) Recommended Mitigation W. Golden Valley 69 kv Interconnection N-0 ALL LINES IN SERVICE GRIFFITH 230/69 kv transformer 80 MVA 162% Add second 80 MW, 230/69 kv transformer N-1 BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A 912 A 119% 118% Bypass overloaded segment by constructing new 69 kv circuit between Griffith and a 69 kv switching station in the vicinity of Boriana Junction (see Appendix D1 & D2) All 3 69 kv Substation Interconnection N-0 ALL LINES IN SERVICE GRIFFITH 230/69 kv transformer 80 MVA 227% Add second and third 80 MW, 230/69 kv transformers BORIANA BORIANATP 69 KV LINE 368 A 107% Bypass overloaded segment by constructing new 69 kv circuit between Griffith and a 69 kv switching station in the vicinity of Boriana Junction (see Appendix D1 & D2) N-1 BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A 912 A 153% 152% Bypass overloaded segment by constructing new 69 kv circuit between Griffith and a 69 kv switching station in the vicinity of Boriana Junction (see Appendix D1 & D2) Table 5: Overloaded transmission facilities and associated recommended mitigation plans (Continued) October

21 COST ESTIMATES (see Appendices D & E for details) The following cost estimates are non-binding and do not include mitigation of issues on other affected systems. These costs include direct costs and UNSE overheads, but do not include any income tax gross-up required to be collected by UNSE to the receipt of a taxable contribution in aid of construction. Pursuant to its Rules & Regulations, UNSE is required to collect an income tax gross-up on any taxable contribution in aid of construction in excess of $500,000. UNS Electric s current gross-up factor is 65.37%. A portion of the income tax gross-up is refunded annually based on the federal income tax depreciation tables applicable to the plant assets received by UNSE. At the end of the fifth year in service, the remaining gross-up will be refunded at a discounted amount using UNS Electric s authorized rate of return over the remaining tax life. The estimating is broken into the connection cost and the mitigation cost for each option. For the Feasibility Study it includes only construction costs associated with the 69 kv system and does not include 69 kv right-of-way costs. This estimating does not include any of the costs to mitigate impacts to the overlying Western Area Power Administration HV and EHV transmission system, as Western has said that they will provide these costs once the study moves to the System Impact Study phase. As such, the costs for each interconnection option are as follows: Industrial: $885k Connection Cost: $825k Includes a 69 kv circuit breaker, switches and protection and an estimated 1 mile of line extension with fiber optic ground wire (OPGW) from the 69 kv point of interconnection on the Transmission Provider s 69 kv system to a high-side disconnect switch at the Interconnection Customers Interconnection Facilities. Protection and communications over new OPGW from Hilltop to Industrial for direct transfer trip to isolate the PV generating plant for faults external to the lateral line extension. A conceptual single-line diagram for the interconnection to Industrial substation is included in Appendix D1 and D2. Mitigation Cost: $60k Includes upgrades to the Hilltop 652 breaker bay to accommodate updating to SEL relaying, addition of direct transfer trip to Industrial and addition of power quality metering. Boriana Junction: $8,755k Connection Cost: $825k Includes a 69 kv circuit breaker, switches and protection at a new five position 69 kv ring bus at Boriana Junction and an estimated 1 mile of line extension with fiber optic October

22 ground wire (OPGW) from the 69 kv point of interconnection on the Transmission Provider s 69 kv system to a high-side disconnect switch at the Interconnection Customers Interconnection Facilities, and protection at Boriana Junction to isolate the PV generating plant for faults external to the lateral line extension. A conceptual singleline diagram for the interconnection to Boriana Junction substation is included in Appendix D1. Mitigation Cost: $7,930k Mitigation includes a new 69 kv breaker bay breaker at Griffith, a 6 mile long 69 kv circuit out of Griffith substation to the vicinity of Boriana Junction, a new five position 69 kv ring bus at Boriana Junction and addition of an 80 MVA, 230/69 kv transformer at Griffith. West Golden Valley: $9055k Connection Cost: $825k Includes a 69 kv circuit breaker, switches and protection and an estimated 1 mile of line extension with fiber optic ground wire (OPGW) from the 69 kv point of interconnection on the Transmission Provider s 69 kv system to a high-side disconnect switch at the Interconnection Customers Interconnection Facilities.. Protection and communications over new OPGW from a ring bus at Boriana Junction to West Golden Valley for direct transfer trip to isolate the PV generating plant for faults external to the lateral line extension. A conceptual single-line diagram for the interconnection to West Golden Valley substation is included in Appendix D1. Mitigation Cost: $8230k Mitigation includes a new 69 kv breaker bay breaker at Griffith, a 6 mile long 69 kv circuit out of Griffith substation to the vicinity of Boriana Junction, a new five position 69 kv ring bus at Boriana Junction and addition of an 80 MVA, 230/69 kv transformer at Griffith. All Projects: $10,405k Connection Cost: $2,475k Includes 1 mile of line extension with fiber optic ground wire (OPGW) to each of the three projects, a 69 kv circuit breaker, switches and protection from the existing 69 kv point of interconnection to a high-side disconnect switch at the point-of-interconnection for the W. Golden Valley and Industrial projects. Interconnection cost for the Boriana Junction project is imbedded in the cost for a five position 69 kv ring bus required as part of mitigation if all three projects are constructed. Protection and communications over new OPGW from Griffith to Boriana Junction and West Golden Valley for direct transfer trip to isolate the PV generating plant for faults external to the lateral line October

23 extension. Mitigation Cost: $7,930k Mitigation includes a new 69 kv breaker bay breaker at Griffith, a 6 mile long 69 kv circuit out of Griffith substation to the vicinity of Boriana Junction, a new five position 69 kv ring bus at Boriana Junction and addition of an 80 MVA, 230/69 kv transformer at Griffith. A conceptual single-line diagram for the interconnection of al the projects is included in Appendix D1. October

24 Appendix A Power Flow Maps October

25 Section 1: Heavy Summer Pre-Project Base Case-Power Flow Map (All Lines in Service) October

26 Section 2: Heavy Summer Post-Project Base Case A1 (Industrial 69 kv) - Power Flow Map (All Lines in Service) October

27 Section 3: Difference Power Flow Map B/N Heavy Summer Pre- & Post-Project Base Case A1 (Industrial 69 kv) October

28 Section 4: Heavy Summer Post-Project Base Case A2 (Boriana 69 kv)-power Flow Map (All Lines in Service) October

29 Section 5: Difference Power Flow Map B/N Heavy Summer Pre- & Post- Project Base Case A2 (Boriana 69 kv) October

30 Section 6: Heavy Summer Post-Project Base Case A3 (Golden Vly 69 kv)-power Flow Map (All Lines in Service) October

31 Section 7: Difference Power Flow Map B/N Heavy Summer Pre- & Post- Project Base Case A3 (Golden Vly 69 kv) October

32 Section 8: Heavy Summer Post-Project Base Case A4 (All 3 Locations)-Power Flow Map (All Lines in Service) October

33 Section 9: Difference Power Flow Map B/N Heavy Summer Pre- & Post- Project Base Case A4 (All 3 Locations) October

34 Section 10: Light Winter Pre-Project Base Case -Power Flow Map (All Lines in Service) October

35 Section 11: Light Winter Post-Project Base Case A1 (Industrial 69 kv) - Power Flow Map (All Lines in Service) October

36 Section 12: Light Winter Post-Project Base Case A2 (Boriana 69 kv) - Power Flow Map (All Lines in Service) October

37 Section 13: Light Winter Post-Project Base Case A3 (Golden Vly 69 kv) - Power Flow Map (All Lines in Service) October

38 Section 14: Light Winter Post-Project Base Case A4 (All 3 Locations) - Power Flow Map (All Lines in Service) October

39 Appendix B Summary of Power Flow Analysis Results October

40 Table B1: Summary of Power Flow Study Results for Heavy Summer Base Case A1 (Industrial 69 kv) Worst Outage Overloaded Facility Applicable Rating Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A1 Comments ALL LINES IN SERVICE NONE N/A N/A N/A None Category B Contingencies BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE 661 A BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE YUCCATAP BKMTNTP1 69 KV LINE 661 A BLK MESA #1 230/69 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER MCCONICO-DAVIS 230 KV LINE & PEACOCK 345/230 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER BLK MESA #1 230/69 KV TRANSFORMER Category C/D Contingencies 45 MVA MVA Overload not attributable to the addition of the proposed project PRSCOTWA RNDVLYTP 230 KV LINE 897 A Overload exacerbated by PEACOCK-RNDVLYTP 230 KV LINE 897 A the addition of proposed project October

41 Table B2: Summary of Power Flow Study Results for Light Winter Base Case A1 (Industrial 69 kv) Worst Outage Overloaded Facility Applicable Rating Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A1 Loading (%) Comments ALL LINES IN SERVICE NONE N/A N/A N/A None Category B Contingencies BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE 661 A BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A YUCCATAP BKMTNTP1 69 KV LINE 661 A Category C/D Contingencies Overload not due to the addition of proposed project NONE NONE N/A N/A N/A Same facility overloads as recorded under category B contingencies October

42 Table B3: Summary of Power Flow Study Results for Heavy Summer Base Case A2 (Boriana 69 kv) Worst Outage Overloaded Facility Applicable Rating ALL LINES IN SERVICE Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A2 Comments GRIFFITH 230/69 KV TRANSFORMER 80 MVA Replace transformer with a 150 MVA rated one BORIANA BORIANATP 69 KV LINE 368 A Rebuild line Category B Contingencies GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A Overload due to GRIFFITH GRIFTAP3 69 KV LINE 912 A KAPVGP.Rebuild the overloaded lines BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE 661 A Overload exacerbated by GRIFFITH GRIFTAP3 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A the addition of proposed project GRIFFITH GRIFTAP3 69 KV LINE YUCCATAP BKMTMTP1 69 KV LINE 661 A BLK MESA #1 230/69 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER GRIFFITH PEACOCK & HILLTOP- MCCONICO 230 KV LINES GRIFFITH PEACOCK & DAVIS- MCCONICO 230 KV LINES MCCONICO-DAVIS 230 KV LINE & PEACOCK 345/230 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER BLK MESA #1 230/69 KV TRANSFORMER Category C/D Contingencies 45 MVA MVA Overload not attributable to the addition of the proposed project MCCONICO DAVIS 230 KV LINE 1336 A Overload due to the addition of proposed project HILLTOP-MCCONICO 230 KV LINE 1336 A PRSCOTWA RNDVLYTP 230 KV LINE 897 A Overload exacerbated by PEACOCK-RNDVLYTP 230 KV LINE 897 A the addition of proposed project October

43 Table B4: Summary of Power Flow Study Results for Light Winter Base Case A2 (Boriana 69 kv) Worst Outage Overloaded Facility Applicable Rating ALL LINES IN SERVICE Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A2 Comments GRIFFITH 230/69 KV TRANSFORMER 80 MVA Overload due to addition of KAPVGP. Replace transformer with a 150 MVA rated one BORIANA BORIANATP 69 KV LINE 368 A Overload due to KAPVGP. Rebuild line Category B Contingencies BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE 912 A Overload due to KAPVGP. GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A Rebuild overloaded lines BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE 661 A BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A YUCCATAP BKMTNTP1 69 KV LINE 661 A Category C/D Contingencies Overload exacerbated by the addition of proposed project None None N/A N/A N/A Same facility overloads as recorded under category B contingencies October

44 Table B5: Summary of Power Flow Study Results for Heavy Summer Base Case A3 (W. Golden Vly 69 kv) Worst Outage Overloaded Facility Applicable Rating Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A3 Comments ALL LINES IN SERVICE GRIFFITH 230/69 KV TRANSFORMER 80 MVA Overload due to addition of KAPVGP. Replace transformer with a 150 MVA rated one Category B Contingencies GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A Overload due to KAPVGP. GRIFFITH GRIFTAP3 69 KV LINE 912 A Rebuild the overloaded lines BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A Overload exacerbated by SACROSUB BKMTNTP2 69 KV LINE 661 A the addition of proposed project BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE YUCCATAP BKMTNTP1 69 KV LINE 661 A BLK MESA #1 230/69 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER PEACOCK-RNDVLYTP 230 KV LINE & PEACOCK 345/230 KV TRANSFORMER GRIFFITH PEACOCK & DAVIS- MCCONICO 230 KV LINES MCCONICO-DAVIS 230 KV LINE & PEACOCK 345/230 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER BLK MESA #1 230/69 KV TRANSFORMER Category C/D Contingencies 45 MVA Overload not attributable to the addition of the proposed 45 MVA project MCCONICO DAVIS 230 KV LINE 1336 A Overload due to the addition of the proposed project HILLTOP-MCCONICO 230 KV LINE 1336 A PRSCOTWA RNDVLYTP 230 KV LINE 897 A Overload exacerbated by the addition of proposed project PEACOCK-RNDVLYTP 230 KV LINE 897 A October

45 Table B6: Summary of Power Flow Study Results for Light Winter Base Case A3 (W. Golden Vly 69 kv) Worst Outage Overloaded Facility Applicable Rating Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A2 Comments ALL LINES IN SERVICE GRIFFITH 230/69 KV TRANSFORMER 80 MVA Overload due to addition of KAPVGP. Replace transformer with a 150 MVA rated one Category B Contingencies BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE 912 A Overload due to addition of GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A KAPVGP. Rebuild overloaded lines BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A Overload exacerbated by SACROSUB BKMTNTP2 69 KV LINE 661 A the addition of proposed project BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A YUCCATAP BKMTNTP1 69 KV LINE 661 A Category C/D Contingencies None None N/A N/A N/A Same facility overloads as recorded under category B contingencies October

46 Table B7: Summary of Power Flow Study Results for Heavy Summer Base Case A4 (All 3 Locations) Worst Outage Overloaded Facility Applicable Rating ALL LINES IN SERVICE Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A4 Comments GRIFFITH 230/69 KV TRANSFORMER 80 MVA Overload due to KAPVGP. Additional transformer required BORIANA BORIANATP 69 KV LINE 368 A Overload due to KAPVGP. Rebuild line Category B Contingencies GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A Overload due to KAPVGP. BKMTNTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE 912 A Rebuild the overloaded lines SACROSUB - GRIFTAP3 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE 661 A BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A SACROSUB BKMTNTP2 69 KV LINE YUCCATAP BKMTNTP1 69 KV LINE 661 A BLK MESA #1 230/69 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER BLK MESA #2 230/69 KV TRANSFORMER BLK MESA #1 230/69 KV TRANSFORMER 45 MVA MVA Overload exacerbated by the addition of proposed project Overload not attributable to the addition of the proposed project October

47 Table B7: Summary of Power Flow Study Results for Heavy Summer Base Case A4 (All 3 Locations) Continued Worst Outage Overloaded Facility Applicable Rating GRIFFITH PEACOCK & HILLTOP- MCCONICO 230 KV LINES GRIFFITH PEACOCK & DAVIS- MCCONICO 230 KV LINES MCCONICO-DAVIS 230 KV LINE & PEACOCK 345/230 KV TRANSFORMER Category C/D Contingencies Pre- Project Case A Loading (%) Post- Project Case A4 MCCONICO DAVIS 230 KV LINE 1336 A HILLTOP-MCCONICO 230 KV LINE 1336 A PEACOCK HILLTOP 230 KV LINE 1336 A Comments Overload due to the addition of proposed project PRSCOTWA RNDVLYTP 230 KV LINE 897 A Overload exacerbated by the addition of proposed project PEACOCK-RNDVLYTP 230 KV LINE 897 A Overload attributable to the addition of the proposed project October

48 Table B8: Summary of Power Flow Study Results for Light Winter Base Case A4 (All 3 Locations) Worst Outage Overloaded Facility Applicable Rating ALL LINES IN SERVICE Category A Normal Overloads Pre- Project Case A Loading (%) Post- Project Case A4 Comments GRIFFITH 230/69 KV TRANSFORMER 80 MVA Overload due to KAPVGP. Additional transformer required BORIANA BORIANATP 69 KV LINE 368 A Overload due to KAPVGP. Rebuild line Category B Contingencies BKMTMTP1 BLK_MTN 69 KV LINE GRIFFITH GRIFTAP3 69 KV LINE 912 A Overload due to addition of GRIFFITH GRIFTAP3 69 KV LINE BKMTMTP1 BLK_MTN 69 KV LINE 912 A KAPVGP. Rebuild overloaded lines BKMTNTP1 BLK_MTN 69 KV LINE SACROSUB - GRIFTAP3 69 KV LINE 661 A Overload exacerbated by SACROSUB BKMTNTP2 69 KV LINE 661 A the addition of proposed project BKMTNTP2 BLK_MTN 69 KV LINE GRIFFITH YUCCATAP 69 KV LINE 661 A YUCCATAP BKMTNTP1 69 KV LINE 661 A Category C/D Contingencies None None N/A N/A N/A Same facility overloads as recorded under category B contingencies October

49 Appendix C Power Flow Contingency List October

50 CATEGORY A RUN 0 CATEGORY BR LINE "LIBERTY " "PEACOCK " RUN 1 CATEGORY BR LINE "PEACOCK " "MEAD " RUN 2 LINE "DAVIS " "MCCULLGH" RUN 3 LINE "DAVIS " "MEAD N " RUN 4 LINE "DAVIS " "RIVIERA " RUN 5 LINE "DAVIS " "TOPOCK " RUN 6 LINE "DAVIS " "ZORB " RUN 7 LINE "GRIFFITH" "PEACOCK " RUN 8 LINE "HARRIS " "MERCATOR" RUN 9 LINE "HILLTOP " "MCCONICO" RUN 10 LINE "MCCONICO" "DAVIS " RUN 11 LINE "MCCONICO" "GRIFFITH" RUN 12 LINE "MCCONICO" "HARRIS " RUN 13 LINE "N.HAVASU" "PARKER " RUN 14 LINE "N.HAVASU" "TOPOCK " RUN 15 LINE "PARKER " "BLK MESA" RUN 16 October

51 LINE "PARKER " "EAGLEYE " RUN 17 LINE "PARKER " "GENE " RUN 18 LINE "PARKER " "HARCUVAR" RUN 19 LINE "PARKER " "HAVASU " RUN 20 LINE "PEACOCK " "HILLTOP " RUN 21 LINE "PRESCOTT" "RNDVLYTP" RUN 22 LINE "RNDVLYTP" "PEACOCK " RUN 23 LINE "TOPOCK " "BLK MESA" RUN 24 LINE "TOPOCK " "SOPOINT " RUN 25 LINE "ZORB " "TOPOCK " RUN 26 LINE "PARKER " "BLYTHE " RUN 27 LINE "PARKER " "BOUSE " RUN 28 LINE "PARKER " "HEADGATE" RUN 29 LINE "PARKER " "PARKERAZ" RUN 30 LINE "BKMTNTP1" "BLK_MTN " RUN 31 LINE "BKMTNTP2" "BLK_MTN " RUN 32 LINE "BORIANTP" "BDRYCONE" RUN 33 October

52 LINE "BORIANTP" "BORIANA " RUN 34 LINE "CANTEX " "AIRPORT " RUN 35 LINE "CANTEX " "IVY_WIRE" RUN 36 LINE "CASSON " "CASSONTP" RUN 37 LINE "CHLORJCT" "PIERFERR" RUN 38 LINE "DUVALBOS" "DUVALRCM" RUN 39 LINE "DUVALBOS" "DUVALTAP" RUN 40 LINE "GRIFFITH" "GRIFTAP1" RUN 41 LINE "GRIFFITH" "GRIFTAP3" RUN 42 LINE "GRIFFITH" "YUCCATAP" RUN 43 LINE "GRIFTAP1" "GRIFTAP2" RUN 44 LINE "GRIFTAP2" "SKINGTAP" RUN 45 LINE "GRIFTAP3" "BORIANTP" RUN 46 LINE "GUARDIAN" "EASTERN " RUN 47 LINE "GUARDIAN" "INDUSTRL" RUN 48 LINE "GVTAP " "GOLDVALL" RUN 49 LINE "GVTAP " "SOHI " RUN 50 October

53 LINE "HIGHWAY " "WILLBECH" RUN 51 LINE "HILLTOP1" "EASTERN " RUN 52 LINE "HILLTOP2" "CASSONTP" RUN 53 LINE "JAGERSON" "AIRPORT " RUN 54 LINE "NKINGTAP" "GVTAP " RUN 55 LINE "NORTKING" "CASSONTP" RUN 56 LINE "PIERFERR" "DOLSPRNG" RUN 57 LINE "PIERFERR" "HIGHWAY " RUN 58 LINE "S.WIRE " "AIRPORT " RUN 59 LINE "S.WIRE " "INDUSTRL" RUN 60 LINE "SACROSUB" "BKMTNTP2" RUN 61 LINE "SACROSUB" "GRIFTAP3" RUN 62 LINE "SKINGTAP" "NKINGTAP" RUN 63 LINE "SKINGTAP" "SOTHKING" RUN 64 LINE "SOHI " "CHLORJCT" RUN 65 LINE "W.GDNTAP" "BORIANTP" RUN 66 LINE "W.GDNTAP" "DUVALTAP" RUN 67 October

54 LINE "W.GDNTAP" "DUVALWTR" RUN 68 LINE "W.GDNTAP" "W.GDNVLY" RUN 69 LINE "WILLBECH" "GOLDSTRK" RUN 70 LINE "YUCCASUB" "YUCCATAP" RUN 71 LINE "YUCCATAP" "BKMTNTP1" RUN 72 CATEGORY BR XFMR "MEAD " "MEAD N " RUN 73 CATEGORY BR XFMR "MEAD " "MEAD N " RUN 74 CATEGORY BR XFMR "MEAD " "MEAD N " RUN 75 CATEGORY BR XFMR "PEACOCK " "PEACOCK " RUN 76 XFMR "BLK MESA" "BLK MESA" RUN 77 XFMR "GRIFFITH" "GRIFFTH1" RUN 79 XFMR "GRIFFITH" "GRIFFTH2" RUN 80 XFMR "GRIFFITH" "GRIFFTH3" RUN 81 XFMR "SOPOINT " "SOPOINT1" RUN 82 XFMR "SOPOINT " "SOPOINT2" RUN 83 XFMR "SOPOINT " "SOPOINT3" RUN 84 XFMR "PARKER " "PARKER " RUN 85 October