XXXXXXXXXXXXXX 99 MW WIND PARK GENERATOR INTERCONNECTION FEASIBILITY STUDY. September 2008 Prepared by: EL PASO ELECTRIC COMPANY

Transcription

1 XXXXXXXXXXXXXX 99 MW WIND PARK GENERATOR INTERCONNECTION FEASIBILITY STUDY September 2008 Prepared by: EL PASO ELECTRIC COMPANY

2 Foreword This report was prepared for XXXXXXXXXXXXX (XXX) of XXXXXXXX by System Planning at. Any correspondence concerning this document, including technical and commercial questions should be referred to: Dennis Malone Manager System Planning Department P.O. Box 982 El Paso, Texas Phone: (915) Fax: (915) Study Performed by: Joaquin Aguilar Principal Engineer Generator Interconnection i September 2008

3 TABLE OF CONTENTS 1.0 Executive Summary...Page Introduction...Page Performance Criteria...Page Methodology...Page Assumptions...Page Procedure...Page Development and Description of Cases...Page List of Contingencies...Page Q-V Analysis...Page Short-Circuit Analysis...Page Powerflow Analysis Results...Page Sensitivity Studies...Page A PNM to EPE Control Area Firm Schedule at West Mesa of 201 MW...Page B PNM to EPE Control Area Firm Schedule at West Mesa of -50 MW...Page Voltage Analysis Results...Page Q-V Analysis Results...Page Short-Circuit Analysis Results...Page Cost Estimates...Page Energy Resource Interconnection Service...Page Disclaimer...Page Certification...Page 26 Generator Interconnection ii September 2008

4 APPENDICIES Generation Interconnection Scope...Appendix 1 EPE s FERC Form 715 Filing...Appendix 2 List of Contingencies...Appendix 3 Q-V Plots...Appendix 4 XXXXXXXXXXXX Modeling Data...Appendix 5 One-Line Maps...Appendix 6 Discretionary Change to System Scope...Appendix 7 Generator Interconnection iii September 2008

5 1.0 EXECUTIVE SUMMARY XXXXXXXXXXXXXXX (XXX) of XXXXXXXXXXXXXXXsubmitted a request for a generator interconnection to the (EPE) system on January 10, This Generator Interconnection request was for a 99 MW wind generation project located approximately 30 miles northeast from Luna 345 kv Substation and interconnected to El Paso Electric Company s (EPE) Springerville-Luna 345 kv line with an in-service date of March 1, A Scoping Meeting was held on February 12, 2008 with the Interconnection Feasibility Study Agreement being signed on February 12, A Scope (Appendix 1) was developed and signed by the parties on May 1, In September 2008, EPE completed the Generator Interconnection (GIFS) for XXX which determined all impacts to the EPE system and southern New Mexico area and to a lesser degree the Arizona area. A 2011powerflow case was developed for powerflow analysis that included three generation interconnection projects senior to the XXXXXXXXXXXX Project. One of those generation interconnection projects was in the System Impact Study Phase (500 MW) and the others were in the Phase (990 MW and 120 MW). The three generation interconnection projects in the EPE Interconnection queue senior to the XXXXXXXXXXXX Project as well as the XXXXXXXXXXXX Project have been modeled in this study such that the generation from these projects is delivered to all entities (and no specific one) in the Western Electricity Coordinating Council (WECC) system. Consequently, no specific transmission path for energy sales has been defined nor does this study guarantee a transmission path will be available when the generator is constructed. A six mile, 115 kv line is to be built between the generation site (XXXXXXXXXXXX Wind Park) and a new 115/345 kv substation to be located on the Springerville-Luna 345 kv line approximately 30 miles from Luna 345 kv Substation ( the Generator Interconnection ). Generator Interconnection 1 September 2008

6 Powerflow results showed that some overload and voltage criteria violations occur in the southern New Mexico and Arizona systems without the addition of the XXXXXXXXXXXX Project. These overload and voltage criteria violations are expected to be corrected by the appropriate generator interconnector senior in the study queue of the XXXXXXXXXXXX interconnection. The primary powerflow analysis in this study was conducted with 141 MW of Afton generation scheduled at West Mesa and a PNM to EPE control area firm schedule of 60 MW. Under this schedule and with all but three contingency scenarios studied, the addition of the XXXXXXXXXXXX Project aggravates slightly those overload and voltage criteria violations previously attributed to those projects senior to the XXXXXXXXXXXX Project. However, the addition of the XXXXXXXXXXXX Project in the southern New Mexico system is directly responsible for three overload criteria violations. The contingency overload criteria violations occur on two transmission lines belonging to Public Service Company of New Mexico (PNM) and one belonging to Tri-State Generation & Transmission Association, Inc. (Tri-State) and include: Central-Hurley 115 kv Luna-Hurley 115 kv El Butte-SocorroP 115 kv PNM s Central-Hurley 115 kv line and Luna-Hurley 115 kv line both overload under the Luna-Hidalgo 345 kv line contingency and Tri-State s El Butte-SocorroP 115 kv line overloads under the Greenlee-Hidalgo 345 kv line contingency. It is important to note that the overloads noted for the transmission lines in the PNM and Tri-State systems were based on ratings shown for the facilities in the base case. These overloaded lines use the same rating value for emergency as they do for normal. At full XXXXXXXXXXXX generation and under the contingencies described above, the Central-Hurley 115 kv line overloads to 101.6% of its normal/emergency rating (4.7% increase compared against the case with no XXXXXXXXXXXX generation), the Luna-Hurley 115 kv line overloads to 103.5% of its normal/emergency rating (4.8% increase compared against the case with no XXXXXXXXXXXX generation) and the Tri-State s El Butte-SocorroP 115 kv line Generator Interconnection 2 September 2008

7 overloads to 102.2% of its normal/emergency rating (4.1% increase compared against the case with no XXXXXXXXXXXX generation). Since these criteria violations are on transmission lines owned by other utilities, this report only identifies the violations and does not provide an indication of the specific facility overloaded (conductor, substation equipment, etc.) or a recommendation for mitigating them. PNM and Tri-State will be informed of these violations and asked to participate in the System Impact Study phase of this project to determine the appropriate mitigation (if required). Other overloaded elements in the southern New Mexico system have also been identified but are attributed to those interconnection projects senior to the XXXXXXXXXXXX project. If any of these interconnection projects should drop out, a re-study at XXX s expense would be required and more Network Upgrades may potentially be attributable to the XXXXXXXXXXXX Project. Fault study results showed that several substation circuit breakers exceeded their capabilities without the XXXXXXXXXXXX Project in service. The XXXXXXXXXXXX Project adds a minimal contribution to the regional fault currents but is not the cause for exceeding the short circuit capabilities of the breakers. For those circuit breakers that exceeded their capabilities, Network Upgrades are expected to be supplied by one of the generation interconnection projects senior to the XXXXXXXXXXXX Project. The powerflow system improvements used in the study case for the 990 MW generation interconnection project included significant VAR support. As such, the XXXXXXXXXXXX Project may benefit from the additional VAR support. Q-V VAR margin study results showed that even with the XXXXXXXXXXXX Project in service there is more than adequate VAR margin on all buses monitored under all lines in service and contingency conditions. If the 990 MW project should drop out, a re-study will be needed to determine if there are any VAR margin deficiencies caused by the XXXXXXXXXXXX Project. Generator Interconnection 3 September 2008

8 The overall study results for this Phase showed that the only EPE system improvements that the XXXXXXXXXXXX Project will be responsible for (other than their generation site, step-up transformers, and transmission line) is the interconnection switching station on the Springerville-Luna 345 kv line and the relocating of the series compensation and line reactors (with breakers) at Luna Substation to the switching station as shown in Section 8.0. This is based on the assumption that the three generation interconnection projects senior to the XXXXXXXXXXXX Project will be implemented and projected system expansions by all utilities in the 2011 powerflow case are implemented as planned. (The overloads on the two PNM lines and the one Tri- State line will need to be addressed with the individual utilities in the System Impact Study if this XXXXXXXXXXXX Project should progress to the next study stage). This study satisfied the request for the Energy Resource Interconnection Service (ERIS) and the Network Resource Interconnection Service. Results of the ERIS can be found in Section 9.0 of this report. EPE agreed through a Discretionary Change to the System Scope (Appendix 7), dated February 12, 2008, that XXX could have their own engineering consultants prepare a good faith cost estimate and construction schedule for interconnecting into the EPE system and any required Network Upgrades. Consequently neither EPE nor its engineering consultant has provided any of this information to be included in this at this time. However, EPE does not warrant the accuracy of the non-epe supplied information. 2.0 INTRODUCTION XXXXXXXXXXXXXXX (XXX) of XXXXXXXXX is proposing to construct 99 MW of wind generation (66 wind turbines at 1.5 MW each) that will interconnect to the southern New Mexico transmission system on EPE s Springerville-Luna 345 kv line. A six mile, 115 kv line is to be built between the generation site (XXXXXXXXXXXX Wind Park) and a new 115/345 kv substation to be located on the Springerville-Luna 345 Generator Interconnection 4 September 2008

9 kv line approximately 30 miles from Luna 345 kv Substation. Proposed in-service date is March 1, As per the requirements of the Federal Energy Regulatory Commission (FERC) Large Generator Interconnection Procedures (LGIP), EPE initiated a Generator Interconnection (GIFS) to study the impact of the interconnection. EPE conducted powerflow, VAR margin and short-circuit analyses. In September 2008, EPE completed the GIFS for XXX which determined all impacts to the EPE system and southern New Mexico area and to a lesser degree the Arizona area. A 2011 powerflow case was developed for powerflow analysis that included three generation interconnection projects senior to the XXXXXXXXXXXX Project. One of those generation interconnection projects was in the System Impact Study Phase (500 MW) and the other two were in the Phase (990 MW and 120 MW). The proposed 345 kv transmission configuration for the 990 MW generation interconnection project is preliminary and will be re-evaluated in the System Impact Study Phase in consultation with PNM if the project continues to the next phase. Also, as previously noted, a re-study of this XXXXXXXXXXXX would need to be conducted if any of the generation interconnection projects senior to the XXXXXXXXXXXX Project decide not to pursue their projects any further. 2.1 PERFORMANCE CRITERIA The reliability criteria standards used by EPE in performing this Study are readily acceptable standards and are listed in Section 4 of EPE s FERC Form 715 (Appendix 2). The powerflow analysis was performed using the GE PSLF program. For precontingency solutions, transformer tap phase-shifting transformer angle movement and static VAR device switching was allowed. For each contingency studied, all regulating equipment (transformer controls and switched shunts) was fixed at pre-contingency positions. All buses, lines, and transformers in the El Paso and surrounding New Mexico control areas with base voltages of 69 kv and above were monitored. Pre-contingency flows on lines and transformers must remain at or below the normal rating of the element, and post-contingency flows on network elements must remain at or Generator Interconnection 5 September 2008

10 below the emergency rating. Flows above 100% of an element s rating are considered violations. The minimum and maximum voltages are specified in EPE s FERC Form 715. Voltages that did not meet criteria in the benchmark cases were considered an exception to the criteria for that specific bus and did not have a penalizing effect when evaluating the XXXXXXXXXXXX generation interconnection. The performance criteria utilized in monitoring the EPE and New Mexico areas are shown below in Table 2-1. Table 2.1: Performance Criteria Area EPEC PNM Tri- State Conditions Normal Contingency Normal ALIS Contingency N-1 Contingency N-2 Normal ALIS Contingency N-1 Contingency N-2 Loading Limits < Normal Rating < Emergency Rating Voltage Voltage (p.u.) Drop Application kV and above Artesia 345 kv Arroyo 345 kv PST source side Alamo, Sierra Blanca and Van Horn 69kV % 60 kv to 115 kv % Artesia 345kV % Arroyo 345kV PST source side Alamo, Sierra Blanca and Van Horn 69kV % Hidalgo, Luna, or other 345 kv buses kv and above* < Normal Rating < Emergency %** 46 kv to 115 kv Rating %** 230 kv and above < Emergency Rating % 46 kv and above* < Normal Rating All buses < Emergency Rating < Emergency Rating %** %** % Tri-State buses served from the PNM System (46 kv to 115 kv) Tri-State buses served from the PNM System (230 kv and above) Tri-State buses served from the Tri- State system % All buses * Taiban Mesa and Guadalupe 345 kv bus voltage must be between 0.95 and 1.1 p.u. under normal and contingency conditions. Generator Interconnection 6 September 2008

11 ** For PNM buses in southern New Mexico and Tri-State buses in southern New Mexico served from the PNM system, the allowable N-1 voltage drop is 7%. Generator Interconnection 7 September 2008

12 3.0 METHODOLOGY 3.1 Assumptions The following assumptions are consistent for all study scenarios unless otherwise noted. System improvement good faith estimated costs and construction schedule for the XXXXXXXXXXXX generation interconnection were to be developed by XXX s consultants. EPE does not warrant the accuracy of this information. This study assumes that all system expansion projects as planned by area utilities by the year under analysis are completed and that any system improvements required by the three generator interconnections senior to the XXXXXXXXXXXX project are implemented. This study did not analyze any transmission service from the interconnection point to any specific point on the grid. It determined Network Upgrades necessary to deliver the proposed XXXXXXXXXXXX generation output uniformly into the entire WECC transmission grid. 3.2 Procedure The analyses in this study included Powerflow, Q-V, and Short-Circuit. Detailed discussions for each topic are included in this report. A description of the procedures used to complete the analyses is shown below Development and Description of Cases A heavy summer load 2011 WECC powerflow case was used with the below modifications to establish a benchmark case without the XXXXXXXXXXXX Project. Benchmark Case: The 2011 benchmark case included the following third party generation: MW of generation (Luna Energy Facility) interconnected at the Luna 345 kv bus and scheduled to the WECC grid. Generator Interconnection 8 September 2008

13 MW of generation (Afton CT) interconnected at the Afton 345 kv Substation and scheduled to PNM through the EPE/PNM control area at the West Mesa 345 kv bus MW of generation (Pyramid) interconnected at PNM s Hidalgo 115 kv Substation and scheduled to the WECC grid MW of generation (Lordsburg) interconnected at PNM s Lordsburg 115 kv Substation and scheduled to the WECC grid MW of generation (Afton ST) interconnected at the Afton 345 kv Substation and scheduled to PNM MW of generation interconnected at EPE s Artesia-Amrad 345 kv line MW of generation interconnected to the EPE and PNM systems in southern New Mexico MW of generation interconnected at the Luna 345 kv Substation in southern New Mexico. Generation Interconnection Case: The XXXXXXXXXXXX Generation Interconnection case modeled the benchmark case described above with the proposed XXXXXXXXXXXX generation in service. The XXXXXXXXXXXX generation output was modeled at a total of 99 MW delivered to WECC List of Contingencies The list of contingencies has been included in Appendix 3. Based on engineering judgment, these contingencies were selected because they represent a good cross section of potential contingencies that would stress the EPE system and PNM s southern New Mexico system. Double contingencies were also analyzed but only for informational purposes to identify potential problem areas. Generator Interconnection 9 September 2008

14 3.2.3 QV Analysis Q-V analyses were performed to verify that the WECC criteria for reactive power margin will be met under the worst contingencies on the EPE system. A procedure developed by WECC was used to determine the reactive power margin. As outlined in this procedure, load was increased by 5% and the worst contingency was analyzed to determine the reactive margin on the system. The margin is determined by identifying the critical (weakest) bus on the system during the worst contingency. The critical bus is the most reactive deficient bus. Q-V curves are developed and the minimum point on the curve is defined as the critical point. If the critical point of the Q-V curve is positive, the system is reactive power deficient. If it is negative, then the system has sufficient reactive power margin and meets the WECC criteria. Prior experience has shown that the worst contingencies impacting reactive power margin are the Springerville-Luna, Luna-Diablo, and Greenlee-Hidalgo 345 kv lines and the buses most impacted are the 345 kv buses at Arroyo, Newman, Caliente, Diablo, Luna, and Hidalgo. All these contingencies and more were analyzed for Q-V margin. The Q-V results are shown on page 20 and the plots for these analyses can be seen in Appendix Short-Circuit Analysis Short-circuit analyses were performed with and without the XXXXXXXXXXXX generation interconnected into the EPE control area. These consisted of substation three phase to ground, two phase to ground, phase to ground, and phase to phase faults. Fault simulations were conducted at several 345 kv and 115 kv buses as shown in the short-circuit analysis table on page 21. The objective of these analyses was to determine the incremental fault current contribution from the XXXXXXXXXXXX generation interconnection and determine if the existing substation breakers in the surrounding area will safely accommodate this additional fault current without exceeding their interruption ratings. The Short-Circuit Analysis report can be found on page 20. Generator Interconnection 10 September 2008

15 4.0 POWER FLOW ANALYSIS RESULTS Powerflow study results for the EPE and PNM load areas showed that no overloads exist in the all lines in service scenarios with or without the XXXXXXXXXXXX Project. However, in the Arizona load area several overloaded elements exist under an all lines in service scenario prior to the addition of the XXXXXXXXXXXX Project. These overloads appear to be caused as a result of the planned 990 MW generation interconnection project, the planned 500 MW generation interconnection project or as existing in the 2011 WECC beginning powerflow case. The Arizona area overloads occur without the XXXXXXXXXXXX Project in service and are slightly aggravated when the XXXXXXXXXXXX Project is added in the powerflow case. A summary of these impacts is shown in the table below that compares the benchmark case (no XXXXXXXXXXXX Project) with the case that includes the XXXXXXXXXXXX Project. ARIZONA AREA - ALL LINES IN SERVICE OVERLOADS 2011 BENCHMARK CASE ( NO XXXXXXXXXXXX) 2011 CASE WITH XXXXXXXXXXXX % OF % OF % FROM TO NORMAL FROM TO NORMAL OVERLOADS BUS KV BUS KV RATING BUS KV BUS KV RATING DELTA BLYTHE 161 BUCKBLVD BLYTHE 161 BUCKBLVD LAGUNATP 69 YUCCA W LAGUNATP 69 YUCCA W SHIPROCK 230 SHIPROCK SHIPROCK 230 SHIPROCK If the Arizona area data modeling is more properly represented in the 2011 WECC case and/or the generation interconnection projects senior to the XXXXXXXXXXXX Project provide for system improvements to relieve the overloading with enough capacity to absorb the delta overloads shown in the above table, XXX will not be expected to provide additional system improvements. However, if the Arizona area data updates and/or Generator Interconnection 11 September 2008

16 system improvements the interconnection projects senior to the XXXXXXXXXXXX Project will be required to make are not enough to correct the overloads caused by the XXXXXXXXXXXX Project, XXX will be responsible for any necessary additional improvements. If this should happen, the issue of overloads in the Arizona system will have to be addressed by XXX directly with the appropriate Arizona entity if the project should move forward to the next study phase. No cost figures for any remedies in the Arizona system have been provided in this study. Powerflow results for contingency scenarios in the New Mexico/EPE areas (see Appendix 3 for list of contingencies) show that in many of the scenarios, overloads existed prior to the addition of the XXXXXXXXXXXX Project. However, as can be seen in the following table, results show that three overloaded transmission lines are identified due to the addition of the XXXXXXXXXXXX project and include: Central-Hurley 115 kv Luna-Hurley 115 kv El Butte-SocorroP 115 kv The numbers in the table shown under the Without XXXXXXXXXXXX and the With XXXXXXXXXXXX columns represent the % of emergency rating for the element shown. The overloads due to the XXXXXXXXXXXX project are highlighted in yellow. It is important to note that the overloads noted for this analysis of the transmission lines in the PNM and Tri-State systems were based on ratings shown for the facilities in the base case. These overloaded lines use the same rating value for emergency as they do for normal. Generator Interconnection 12 September 2008

17 2011 SINGLE CONTINGENCIES From Bus kv To Bus kv Without XXXXXXXXXXXX With XXXXXXXXXXXX Delta Owner Contingency AVILA_T 115 NO_BERN NM B-A- RIOPUERC1345 B-A 115 B-A NM B-A- RIOPUERC1345 B-A 115 ENCHNTED NM B-A- RIOPUERC1345 B-A 115 NO_BERN NM B-A- RIOPUERC1345 BLYTHE 161 BUCKBLVD AZ MANY CENTRAL 69 CENTRAL NM HID-LORSBRG115 CENTRAL 115 HURLEY_# NM LUNA -HID 345 CENTRAL 69 LORDSBRG NM HID-LORSBRG115 CENTRAL 69 SILVER_C NM TURQUOIS 69/115 CHOLLA 345 CHOLLA AZ SPRGR-VAIL 345 GREEN- COPPERVR 345 COPPERVR AZ WINCH345 EAST_TAP 115 EMBUDO NM WM-SANDIA 345 CAB-MIMBRES EL_BUTTE 115 PICACHO NM 115 EL_BUTTE 115 SOCORROP NM GRN-HID345 ENCHNTED 115 CHAYOTE NM B-A- RIOPUERC1345 GREEN-AE 230 GREEN-AE AZ GREEN- WINCH345 LAGUNATP 69 YUCCA W AZ MANY LORDSBRG 69 LORDSBRG NM HID-LORSBRG115 LUNA 115 HURLEY_# NM LUNA -HID 345 LUNA 115 LUNA NM LUNA -HID 345 RIOPUERCO- PANORAMT 115 VERANDAT NM WM1345 PERSON 115 PROSPER NM WM-SANDIA 345 SHIPROCK 230 SHIPROCK AZ MANY Notes: 1. The numbers shown under the Without XXXXXXXXXXXX and the With XXXXXXXXXXXX columns represent the % of emergency rating for the element shown. 2. Owner: NM=New Mexico, AZ=Arizona 3. Impact of adding XXXXXXXXXXXX Project - New Mexico overloaded transmission elements owners & ratings: a. Central-Hurley 115 KV PNM (normal rating = 131 MVA, eme rgency rating = 131 MVA) b. El_Butte-SocorroP 115 KV Tri-State (normal rating = 60 MVA, emergency rating = 60 MVA) c. Luna-Hurley_# 115 KV PNM (normal rating =131 MVA, emergency rating = 131 MVA) Generator Interconnection 13 September 2008

18 The following table identifies potential problems under double contingency conditions and is presented here for informational purposes only. No mitigations to these overloads were studied for this. From Bus kv To Bus kv 2011 DOUBLE CONTINGENCIES Without XXXXXXXXXXXX With XXXXXXXXXXXX Delta Area Contingencies BLK MESA 230 BMA.3WP AZ MANY BLK MESA 230 BMA.3WP AZ MANY BLYTHE 161 BUCKBLVD AZ MANY CENTRAL 115 HURLEY_# NM LUN-HID,LUNA -DIA CENTRAL 115 TURQUOIS NM 2 HIDALGO AUTOS DONA_ANA 115 LAS_CRUC NM LUN-HID,LUNAUTO DONA_ANA 115 PICACHO NM LUN-HID,LUNAUTO EL_BUTTE 115 PICACHO NM LUN-AFT,LUNAUTO EL_BUTTE 115 PICACHO NM LUN-HID,LUNAUTO EL_BUTTE 115 SOCORROP NM HID-GR,HIDAUTO2 HIDALGO 115 TURQUOIS NM 2 HIDALGO AUTOS LAGUNATP 69 YUCCA W AZ MANY LORDSBRG 69 LORDSBRG NM TUR-H,TUR-PD115 LORDSBRG 69 LORDSBRG NM 2 HIDALGO AUTOS LUNA 115 HURLEY_# NM LUN-HID,LUNA -DIA LUNA 115 LUNA NM LUN-HID,LUNA -DIA SHIPROCK 230 SHIPROCK AZ MANY EPE System One-Line Diagrams with all lines in service and with and without the XXXXXXXXXXXX project can be found in Appendix Sensitivity Studies 4.1A PNM to EPE Control Area Firm Schedule at West Mesa of 201 MW - The powerflow studies discussed above were based on a PNM to EPE Control Area Firm Schedule at the West Mesa 345 kv bus of 60 MW and with Afton generation of 141 MW scheduled to PNM through this control area. This scenario is a very likely operating scenario but in the event that the maximum north to south (PNM to EPE) contract firm Generator Interconnection 14 September 2008

19 schedule of 201 MW is exercised (no Afton generation), a sensitivity analysis on transmission loading was conducted using contingency set #1. The tables below compares the loading of area in the majority of scenarios, the most stressful case is when the PNM to EPE control area firm schedule at West Mesa is at 60 MW. WITHOUT XXXXXXXXXXXX % of Emergency Rating FROM BUS KV AREA TO BUS KV 60* 201* CONTINGENCY DELTA CENTRAL 69 NM SILVER_C TURQUOIS 69/ EL_BUTTE 115 NM PICACHO CAB-MIMBRES LUNA 115 NM LUNA LUNA -HID BLYTHE 161 AZ BUCKBLVD MANY 0 COPPERVR 345 AZ COPPERVR GREEN-WINCH GREEN-AE 230 AZ GREEN-AE GREEN-WINCH LAGUNATP 69 AZ YUCCA W MANY 0 SHIPROCK 230 AZ SHIPROCK MANY 2.3 WITH XXXXXXXXXXXX % of Emergency Rating FROM BUS KV AREA TO BUS KV 60* 201* CONTINGENCY DELTA CENTRAL 69 NM SILVER_C TURQUOIS 69/ CENTRAL 115 NM HURLEY_# LUNA -HID EL_BUTTE 115 NM PICACHO CAB-HOTSPRGS EL_BUTTE 115 NM PICACHO CAB-MIMBRES EL_BUTTE 115 NM PICACHO HOTSPRG-CUCH EL_BUTTE 115 NM PICACHO LUNA -MIMBRES EL_BUTTE 115 NM SOCORROP GRN-HID LUNA 115 NM LUNA LUNA -HID LUNA 115 NM HURLEY_# LUNA -HID BLYTHE 161 AZ BUCKBLVD MANY 0 COPPERVR 345 AZ COPPERVR GREEN-WINCH GREEN-AE 230 AZ GREEN-AE GREEN-WINCH345-3 LAGUNATP 69 AZ YUCCA W MANY 0 SHIPROCK 230 AZ SHIPROCK MANY 2.2 * PNM to EPE control area firm schedule at West Mesa 345 kv bus Generator Interconnection 15 September 2008

20 4.1B PNM to EPE Control Area Firm Schedule at West Mesa of -50 MW Under the EPE/PNM Settlement Agreement, a 50 MW south to north schedule at West Mesa 345 kv should be accommodated with Afton generation on. Results of this sensitivity analysis showed that this schedule was able to be maintained. Note: The PNM to EPE Control Area Firm Schedule at the West Mesa 345 kv is based on firm contract schedules within the range of -50 to 201 MW. The sensitivity studies above show that some overloads occur within this schedule range. EPE does not allow rescheduling over this control area interchange point as a matter of course for alleviating overloads identified in the above tables. Generator Interconnection 16 September 2008

21 5.0 VOLTAGE ANALYSIS RESULTS Transmission bus voltage profiles were monitored in the EPE, southern New Mexico and Arizona areas for the powerflow cases with and without the XXXXXXXXXXXX Project. Bus voltage comparison tables were created for all lines in service (ALIS) and select worst contingency conditions to evaluate the impact of bus voltages due to the XXXXXXXXXXXX generation interconnection. The reason this was done was because it was noted that in the case without the XXXXXXXXXXXX Project there were some bus voltages (especially in Arizona) that were not meeting voltage criteria. After further review of the Arizona system it was concluded that the low bus voltage profiles in Arizona were primarily due to inadequate system modeling by Arizona utilities in the beginning powerflow case. As can be seen in the tables below, the impact of the XXXXXXXXXXXX generation interconnection is minimal on area voltage profiles. Area bus voltage deltas greater than per unit are shown below. ALL LINES IN SERVICE VOLTAGE COMPARISON WITHOUT XXXXXXXXXXXX WITH XXXXXXXXXXXX PER UNIT PER UNIT BUS KV VOLTAGE AREA BUS KV VOLTAGE DELTA AMISTAD NM AMISTAD WESTMESA NM WESTMESA SILVER_C NM SILVER_C TYRONE NM TYRONE DEMINGTS NM DEMINGTS VANBUREN NM VANBUREN SANDIA NM SANDIA IVANHOE NM IVANHOE CUCHILLO NM CUCHILLO ELBUT_US NM ELBUT_US EL_BUTTE NM EL_BUTTE HOT_SPRG NM HOT_SPRG WESTMESA NM WESTMESA Generator Interconnection 17 September 2008

22 VOLTAGE COMPARISON FROM WORST CONTINGENCY LIST #1 WITHOUT XXXXXXXXXXXX WITH XXXXXXXXXXXX PER UNIT PER UNIT BUS KV VOLTAGE AREA BUS KV VOLTAGE DELTA SILVER_C NM SILVER_C TYRONE NM TYRONE IVANHOE NM IVANHOE CENTRAL NM CENTRAL CENTRAL NM CENTRAL HURLEY_# NM HURLEY_# CHINO NM CHINO Generator Interconnection 18 September 2008

23 6.0 Q-V ANALYSIS RESULTS Q-V analyses were conducted in order to verify that the scenarios modeled in this Study comply with the WECC Voltage Stability Criteria. The analysis provides a way to investigate the potential for voltage collapse during the post-transient period within 3 minutes after the disturbance. Analyses were performed on the benchmark and XXXXXXXXXXXX powerflow cases. A procedure developed by WECC was used to determine the reactive power margin. As outlined in the procedure, load is increased by 5% and the worst contingency is analyzed to determine the reactive margin on the system. The margin is determined by identifying the critical (weakest) bus on the system during the worst contingency. The critical bus is the most reactive deficient bus. Q-V curves are developed and the minimum point on the curve is the critical point. If the minimum point of the Q-V curve is positive, i.e., above the x-axis, the system is reactive power deficient. If it is negative, i.e., below the x-axis, then the system has some reactive power margin and meets the WECC criteria. From experience, it has been established that the worst contingency impacting reactive power margin on the EPE system is an outage of the Luna-Diablo 345 kv line. This single contingency along with single contingencies of the Springerville-VLTap 345 kv, VLTap-Luna 345 kv, Westmesa-Ft. Craig PST 345 kv, Greenlee-Hidalgo 345 kv, Ft. Craig-VLTap 345 kv, Ft. Craig-Arroyo 345 kv, and Newman-Afton 345 kv lines were simulated and analyzed for Q-V margin. The Arroyo, Luna, Caliente, Newman, and Diablo 345 kv buses were monitored for Q-V margins (as shown in the tables below) to verify that EPE reactive power margins are in compliance with the WECC criteria. As can be seen, there is more than enough VAR margin to meet criteria. Resulting plots can be found in Appendix 4. Note that a negative number indicates that there is sufficient reactive power to meet WECC criteria and a positive number indicates that the system is deficient in reactive power and does not meet the criteria. Generator Interconnection 19 September 2008

24 2011 Heavy Summer Load Case Q-V Margin (MVAR) Springerville-VLTap 345 kv Line Outage Greenlee-Hidalgo 345 kv Line Outage Without With Without With XXXX XXXX XXXX XXXX Bus XXXX XXXX Bus XXXX XXXX Arroyo 345 kv Arroyo 345 kv Luna 345 kv Luna 345 kv Caliente 345 kv Caliente 345 kv Newman 345 kv Newman 345 kv Diablo 345 kv Diablo 345 kv Luna-Diablo 345 kv Line Outage Ft. Craig-VLTap 345 kv Line Outage Without With Without With XXXX XXXX XXXX XXXX Bus XXXX XXXX Bus XXXX XXXX Arroyo 345 kv Arroyo 345 kv Luna 345 kv Luna 345 kv Caliente 345 kv Caliente 345 kv Newman 345 kv Newman 345 kv Diablo 345 kv Diablo 345 kv VLTap-Luna 345 kv Line Outage without XXXXXXXXXXXX VLTap-SLPOI kv Line Outage with XXXXXXXXXXXX Ft. Craig-Arroyo 345 kv Line Outage Without With Without With XXXX XXXX XXXX XXXX Bus XXXX XXXX Bus XXXX XXXX Arroyo 345 kv Arroyo 345 kv Luna 345 kv Luna 345 kv Caliente 345 kv Caliente 345 kv Newman 345 kv Newman 345 kv Diablo 345 kv Diablo 345 kv Westmesa-Ft. Cr aig PST 345 kv Line Outage Newman-Afton 345 kv Line Outage Without With Without With XXXX XXXX XXXX XXXX Bus XXXX XXXX Bus XXXX XXXX Arroyo 345 kv Arroyo 345 kv Luna 345 kv Luna 345 kv Caliente 345 kv Caliente 345 kv Newman 345 kv Newman 345 kv Diablo 345 kv Diablo 345 kv Generator Interconnection 20 September 2008

25 7.0 SHORT-CIRCUIT RESULTS Short-circuit (fault) analyses were performed with and without the XXXXXXXXXXXX generation interconnected into the EPE system. The objective of this analysis was to determine the incremental fault current contribution from the XXXXXXXXXXXX generation interconnection and determine if the existing substation circuit breakers can safely accommodate this additional fault current without exceeding their interruption ratings. Study results are shown in the tables below and show that in the benchmark case that already certain circuit breaker short-circuit capabilities are exceeded and are further aggravated when the XXXXXXXXXXXX Project is added to the system. Consequently, XXX will not be assigned circuit breaker upgrade responsibilities but are expected to be resolved by one of the generation interconnection projects that are senior to the XXXXXXXXXXXX Project in the study queue. The powerflow and short-circuit modeling data supplied by XXX and used in the modeling of the XXXXXXXXXXXX Project are shown in Appendix 5. The short-circuit data was enhanced with GE shortcircuit data from a previous study using similar wind generators. Generator Interconnection 21 September 2008

26 Fault Current (Amps) Fault Current (Amps) Fault Current (Amps) Without XXXX With XXXX Increase Due to XXXX Generation XXXX Generation XXXXXXXXXXXX Generation Substation Amps (1) 3Ø-g 2Ø-g 1Ø-g L-L 3Ø-g 2Ø-g 1Ø-g L-L 3Ø-g 2Ø-g 1Ø-g L-L Amrad 345 kv 40, Amrad 115 kv 40, Caliente 345 kv 40, Caliente 115 kv 40, Afton 345 kv 50, Arroyo 345 kv 25, Arroyo 115 kv 22, Diablo 345 kv 40, Diablo 115 kv 32, LEF 345 kv 40, Luna 345 kv 40, Luna 115 kv 20, Newman 345 kv 40, Newman 115 kv 40, Ascarate 115 kv 19, Ft. Craig 345 kv (2) VLTap 345 kv (2) Z345 kv (2) SLPOI 345 kv (2) n/a n/a n/a n/a n/a n/a n/a n/a SLPOI 115 kv (2) n/a n/a n/a n/a n/a n/a n/a n/a SL 115 kv (2) n/a n/a n/a n/a n/a n/a n/a n/a Lunasol 345 kv (2) B-A 345 kv 40, Springerville 345 kv 40, Westmesa 345 kv 40, Picante 345 kv (2) Picante 115 kv (2) Rio Grande 115 kv 20, Rio Grande 69 kv 25, (1) Lowest rating in amperes of any breaker at substation bus (2) To be engineered Generator Interconnection 22 September 2008

27 8.0 COST ESTIMATES Through a Discretionary Change to the System Facility Study Scope (Appendix 7), EPE agreed to allow XXX to have their consultants prepare a good faith cost estimate and construction schedule for interconnecting into the EPE system and for any required Network Upgrades. Consequently no cost or timing information in this has been provided by EPE or its cost estimate consultant. Additionally, EPE does not warrant any cost information developed by XXX or its consultant. The diagram below shows the point of interconnection on the Springerville-Luna 345 kv line of the XXXXXXXXXXXX generation. To Springerville Substation thru VL-Tap Substation Series capacitors, reactors & their breakers relocated from Luna XXXXXXXXXXXX Wind Farm 99 MW Total Generation 345/115 kv 200/224 MVA 6 miles 115/34.5 kv SLPOI 345 kv Substation 200/224 MVA 30 miles to Luna Substation A list of cost estimates to be addressed by XXX s consultants should include at least the following: 1. Sixty-six wind generators (1.5 MW each) and associated wind generation park facilities. 2. A 115/34.5 kv, 200/224 MVA step-up transformer (as per original.epc file submitted by XXX). The latest information from XXX is that the new MVA size will be 100/133/ Six miles of 954 ACSR, 115 kv transmission line. Generator Interconnection 23 September 2008

28 4. A 345/115 kv, 200/224 MVA interconnection transformer (as per original.epc file submitted by XXX). The latest information from XXX is that the new MVA size will be 100/133/ SLPOI 345 kv Substation with three 345 kv breakers and associated facilities. 6. Relocation of the series capacitors and reactors (with breakers) from the Luna end of the Springerville-Luna 345 kv line to SLPOI Substation as shown above. Additional Network Upgrades needed on third party systems include: 1. Determine Tri-State s El Butte-SocorroP 115 kv line (4/0 ACSR conductor, miles, rated 60 MVA normal & emergency) facility limitation. Any appropriate mitigation will be developed in the System Impact Study after consultation with Tri- State. 2. Determine PNM s Central-Hurley 115 kv line (477 ACSR conductor, 6.6 miles, rated 131 MVA normal & 131 MVA emergency) facility limitation. Any appropriate mitigation will be developed in the System Impact Study after consultation with PNM. 3. Determine PNM s Luna-Hurley 115 kv line (477 ACSR conductor, 36.4 miles, rated 131 MVA normal & emergency) facility limitation. Any appropriate mitigation will be developed in the System Impact Study after consultation with PNM. More detailed mitigation for the conductor overloads shown in this study on neighboring utilities (if required) as well as more specific facility requirements and specifications will be developed as a component of the System Impact Study if the study should continue to the next phase. Generator Interconnection 24 September 2008

29 9.0 ENERGY RESOURCE INTERCONNECTION SERVICE As requested by XXX and as per part of EPE s Open Access Transmission Tariff, this includes an analysis of the Energy Resource Interconnection Service. This service is meant to identify the maximum allowable output of the interconnecting XXXXXXXXXXXX generation that would require no additional Network Upgrades under all lines in service (ALIS) and single contingency conditions. This analysis was conducted by increasing the XXXXXXXXXXXX generation output until transmission element overloads start to occur under ALIS and contingency conditions. Results showed that overloads start to occur when the XXXXXXXXXXXX generation is at 49 MW. As previously mentioned, some transmission elements in the powerflow database are rated the same value for both the normal and emergency rating. These results were based on analysis of the powerflow case when loads were at peak value. In the System Impact Study, the powerflow case will be analyzed at peak load as well as some lower load level and may change the results due to the change in counter flows at lower load levels. Note: If those generation interconnection projects senior to XXXXXXXXXXXX in the EPE study queue should change or drop out, a restudy of the XXXXXXXXXXXX interconnection would be required and may change these results. Generator Interconnection 25 September 2008

30 10.0 DISCLAIMER This study assumes that transmission service has not been obtained by XXX to deliver its XXXXXXXXXXXX generation output. Therefore, this Study modeled the XXXXXXXXXXXX power output as being distributed evenly across the entire WECC electrical grid. Whenever XXX determines where it will deliver its generation output to, XXX will have to purchase the required transmission service from the appropriate entity and a Transmission Service Study will be performed to determine the impacts of the XXXXXXXXXXXX transmission path on the EPE and surrounding transmission systems. This study makes no warranties as to the existence or availability of any transmission service XXX will need in order to deliver its XXXXXXXXXXXXXXX generation output. Also, the transfer capacities of certain transmission lines and paths within the southern New Mexico transmission system are limited by contracts between the New Mexico transmission owners and any use of the transfer capacities above the contractual limits will require approval by the contractual parties and renegotiation of the applicable contract(s). If any of the project data used in this study and provided by XXX varies significantly from the actual data once the XXXXXXXXXXXX equipment is installed, the results from this study will need to be verified with the actual data at the Project developer's expense. Additionally, any change in the generation in EPE s Interconnection Queue that is senior to the XXXXXXXXXXXX Project will require a re-evaluation of this Study. Generator Interconnection 26 September 2008

31 11.0 CERTIFICATION (EPE) performed a Generation Interconnection Feasibility Study (GIFS) for XXXXXXXXXXXXX (XXX) pursuant to XXX s letter requesting to interconnect its XXXXXXXXXXXX wind powered generating plant to EPE s Springerville-Luna 345 kv line. The Study determined the impacts to the EPE and surrounding transmission systems due to the interconnection planned for March 1, This recommends Network Upgrades required for mitigating potential impacts due to the addition of the XXXXXXXXXXXX generation. Cost estimates and construction schedules at the generation site and for the transmission interconnection were not provided in this Phase as requested by XXX. XXX s engineering consultants were to provide those items. The powerflow and short-circuit data used to model the XXXXXXXXXXXX generation was supplied by XXX and enhanced with GE short-circuit data from a previous study using similar wind generators. EPE performed power flow, Q-V reactive margin, and short-circuit analyses in this study. Name: Dennis H. Malone Title: Manager, System Planning Signature: Date: Investigating Engineer: Joaquin Aguilar Generator Interconnection 27 September 2008