EL PASO ELECTRIC COMPANY (EPE) FACILITIES STUDY FOR PROPOSED HVDC TERMINAL INTERCONNECTION AT NEW ARTESIA 345 KV BUS

Transcription

1 EL PASO ELECTRIC COMPANY (EPE) FACILITIES STUDY FOR PROPOSED HVDC TERMINAL INTERCONNECTION AT NEW ARTESIA 345 KV BUS El Paso Electric Company System Operations Department System Planning Section May 2004

2 TABLE OF CONTENTS 1.0 Executive Summary...Page Introduction...Page Performance Criteria...Page Voltage Violation Criteria...Page Loading Violation Criteria...Page Methodology...Page Assumptions...Page Procedure...Page Base Case Development and Description of Cases...Page Powerflow Analysis...Page Delta Analysis...Page Q-V Analysis...Page Transient Stability Analysis...Page Powerflow Analysis Results...Page Delta V Analysis Results...Page Q-V Analysis Results...Page Case 1...Page Case 2...Page Case 3...Page Case 4...Page Case 1...Page Case 2...Page Case 3...Page Case 4...Page Transient Stability Analysis Results...Page Case 1...Page Case 2...Page Case 3...Page Case 4...Page Case 1...Page Case 2...Page Case 3...Page Case 4...Page 32 Facilities Study For Proposed HVDC Terminal i El Paso Electric Company

3 TABLE OF CONTENTS 8.0 Cost Estimates...Page Disclaimer...Page Certification...Page 35 Facilities Study For Proposed HVDC Terminal ii El Paso Electric Company

4 APPENDICIES EPE s FERC Form 715 Filing...Appendix 1 Powerflow Maps One-Line Diagrams...Appendix 2 List of Contingencies...Appendix 3 Contingency Powerflow Analyses Table Results...Appendix 4 Delta V Table Results...Appendix 5 Q-V Plots...Appendix 6 Stability Plots...Appendix 7 Facilities Study For Proposed HVDC Terminal iii El Paso Electric Company

5 1.0 EXECUTIVE SUMMARY El Paso Electric Company s Generation Division (EPEGD) submitted a request to System Planning for a Facilities Study of a proposed new project for native load service. The purpose of this Facility Study is to determine all impacts on the El Paso Electric (EPE) system due to the interconnection of a new HVDC terminal with Southwestern Public Service Company (SPS) at Artesia, New Mexico. The proposed HVDC terminal will provide up to 200 MW of additional native load service for EPE and will be located near the existing SPS HVDC terminal located in Artesia, New Mexico. The Study analyzed the HVDC configuration as being paralleled with the existing HVDC terminal. System Planning analyzed the proposed increase in interconnection capacity assuming that a second Artesia to El Paso 345 kv transmission line, in addition to the existing Artesia-Amrad 345 kv line, will be needed to accommodate the new HVDC terminal. Two options were considered, a second line from then new Artesia HVDC terminal to Amrad 345 kv Substation, or a new line from the new Artesia terminal to Caliente 345 kv Substation. Based on lower costs and greater system reliability, the Artesia-Caliente 345 kv line option was selected as the option to analyze in this study. System modifications to correct impacts to the EPE transmission system and estimated costs of these modifications were recommended in this Study. As requested by EPEGD, the proposed HVDC terminal will deliver up to 200 MW of power into the EPE system in addition to the power already being delivered by the existing HVDC terminal at Artesia Substation. The proposed HVDC terminal was modeled as a resource for serving native load. This study analyzed 2008 and 2013 Heavy Summer (HS) and Light Winter (LW) base case scenarios. In the 2013 scenarios, the Rio Grande (RG) 6 and 7 generating units were modeled as having been retired and replaced by a new EPE owned Newman 5 generation unit. Each case was studied using the reliability criteria and methodologies described in subsequent sections of this report. This Study included power flow, Q-V reactive margin, delta-v, and transient stability analyses. Four cases representing the 2008 and 2013 HS and LW seasons were modeled. Descriptions of these cases are listed below: Case 1: Case 2: Case 3: Case 4: Case with the proposed HVDC terminal modeled to provide 50 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 100 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 150 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 200 MW of power into EPE s system. Facilities Study For Proposed HVDC Terminal 1 El Paso Electric Company

6 Sensitivity powerflow analyses were performed on the 2008 HS cases described above. These sensitivities analyzed single contingency conditions under two different HVDC terminal interconnection configurations, one with the new HVDC terminal operating separately to the existing HVDC terminal and the other with the new HVDC terminal tied to the existing HVDC terminal. These analyses were performed to determine whether the two HVDC terminals (new and existing) should be tied together or operated independently of each other for system reliability reasons. The concern of tying the two terminals together was whether the EPE underlying transmission system could handle up to 400 MW of power flow in the event that either of the two lines coming out of Artesia (Amrad-Artesia 345 kv line or the new Artesia-Caliente 345 kv line) and their interconnections to the EPE system were lost due to a single contingency situation. These analyses determined that the underlying transmission system can handle the increased power flow in the event of an outage of either of the 345kv lines with no criteria violations. It was determined that tying the two terminals together will provide the best scenario for providing the greatest reliability to the system. Therefore, all subsequent cases were analyzed using the configuration with the two HVDC terminals tied together. System Impact Estimated Costs Utilizing study results and engineering judgment, proposed system modifications to correct the criteria violations found in the analyses and estimated costs for those proposed modifications are included in this Study. Further analyses of the system with the recommended modifications installed were performed to insure that these modifications will relieve all reliability criteria violations found in the analyses. Results of the analyses show that two criteria violations occur on the existing EPE system when the proposed HVDC terminal is interconnected into the EPE system. Power flow analyses revealed overloading violations of the Arroyo and Caliente 345/115 kv transformers due to the interconnection of the proposed project. The Caliente autotransformer overload occurs during single contingency outage conditions in all cases modeling the proposed project in the 2008 HS scenarios. The Arroyo autotransformer overload occurs in all cases where the proposed project is delivering 100 MW or more (Cases 2-4) to the EPE system in the 2008 HS scenarios. The estimated costs of these two system modifications are shown below: SYSTEM MODIFICATIONS AND ESTIMATED COSTS FOR PROPOSED HVDC TERMINAL ESTIMATED SYSTEM MODIFICATION * YEAR COST (2004$) Add 2 nd Arroyo 200 MVA 115/345 kv autotransformer $2,710,050 Add 3 rd Caliente 200 MVA 115/345 kv autotransformer $2,710,050 TOTAL COSTS $5,420,100 * Estimates include all material (i.e. breakers, switchgear, relays, etc.) necessary for the installation as well as labor required for installation. Facilities Study For Proposed HVDC Terminal 2 El Paso Electric Company

7 Caliente-Artesia2 345 kv Line Estimated Costs In addition to the cost estimates shown above, the cost to build the new 345 kv transmission line from the new HVDC terminal (Artesia2) to Caliente 345 kv Substation, the cost to install the 50 MVAR line reactors on each end of the new line required for line switching, and the cost for any associated substation work needed to connect the line are also included in this Study. The cost for these system improvements are estimated to be as follows: Caliente Substation In order to connect the new line from the proposed Artesia2 Sub, it will be necessary to build a new 345kV bay, and connect it to the 345 kv ring bus. To do this, one 345kV breaker and one 345kV disconnect switch into the ring bus will be needed. This will create a new position for connecting the new line. A 345 kv 50 MVAR reactor will be connected to the line in parallel through a 345 kv circuit breaker and a 345 kv disconnect switch. Since there is no room available in the existing control house, it will be necessary to expand the control house at least 18 ft, to accommodate seven relay racks, and an additional RTU. Land acquisition, right of way and permits costs are not included. These substation costs at Caliente are in addition to the estimated costs to install the third 345/115 kv autotransformer recommended above. TOTAL $2,772,000 * * Includes 50 MVAR reactor, bus work, breaker, disconnect switch, control house expansion, relays, RTU, and labor necessary to connect the new line into Caliente Substation Artesia2 Substation The configuration to connect the new line from Caliente sub will have three 345 kv breakers; one connecting the line to the new DC Tie, another will be the reactor breaker and the third will be part of the partial ring bus. Each breaker will have two sets of disconnect switches except the reactor breaker which will only have one set. The line will have a 345 kv 50 MVAR reactor connected for line switching. It is assumed that the relay racks will be in the control house where the new DC Tie will be located. The cost for the DC Tie and its control house as well as land acquisition, right of way and permits costs are not included in this estimate. TOTAL $2,897,000 * * Includes 50 MVAR reactor, bus work, breakers, disconnect switches, relays, and labor necessary to connect the new line into the new Artesia2 Substation. Facilities Study For Proposed HVDC Terminal 3 El Paso Electric Company

8 170 mile 345 kv Transmission Line from Caliente-Artesia2 This estimate includes material (structures and conductor), labor, engineering, surveying, inspection and permitting. Right of way and land acquisition are not included. TOTAL $104,550,000 Therefore, the total estimated cost to construct the line (including modifications to the substations to connect the line) is $110,219,000. The total estimated costs of the project are show below: System Impacts Cost $5,420,100 Caliente-Artesia2 345 kv line Cost $110,219,000 Estimated Total Project Cost $115,639,100. This study also assumes that the proposed HVDC terminal will be designed to include a Static Var Compensating (SVC) device that regulates voltage levels in the area and provides a 100% load factor correction at the new HVDC terminal (Artesia2). Delta-V, Q-V, and Transient Stability analyses indicate that the transmission system will require this SVC device to have a range of at least 50 capacitive (MVAC) and 130 reactive (MVAR) to maintain voltage stability during single contingency or fault conditions. More detailed studies will need to be performed in order to determine the exact size of this device. Costs for the design and construction of the proposed terminal (including the SVC) have not been included in this Study. However, a previous study performed in April 1999 estimated costs to construct an HVDC terminal similar to the one being studied here to be between $45 million and $50 million. Facilities Study For Proposed HVDC Terminal 4 El Paso Electric Company

9 2.0 INTRODUCTION This study was performed in response to a request for a Transmission and Facilities Study by El Paso Electric Company s Generation Division (EPEGD) to determine any impacts on the El Paso Electric (EPE) system due to the interconnection of a new HVDC terminal power resource to the EPE system. The proposed HVDC terminal will provide up to 200 MW of power to EPE and will be located next to the existing SPS HVDC terminal located in Artesia, New Mexico. EPEGD has requested that EPE T&D analyze the proposed interconnection assuming that a new 345 kv transmission line from the proposed HVDC terminal to EPE s Caliente Substation will be built to import the power into the EPE system. Modifications needed to correct impacts to the EPE system along with estimated costs are provided in this Study. As requested by EPEGD, the proposed HVDC terminal will deliver up to 200 MW of power into the EPE system in addition to the power that is already being delivered by the existing HVDC terminal at Artesia Substation. The proposed project was modeled as a source for serving native load only. This Study analyzed power flow, Q-V reactive margin, delta-v, and transient stability analyses. Four cases, representing 2008 and 2013 Heavy Summer (HS) and Light Winter (LW) seasons were modeled. Descriptions of the cases studied are listed below: Case 1: Case 2: Case 3: Case 4: Case with the proposed HVDC terminal modeled to provide 50 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 100 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 150 MW of power into EPE s system. Case with the proposed HVDC terminal modeled to provide 200 MW of power into EPE s system. Sensitivity powerflow analyses were performed on the 2008 HS cases described above. These sensitivities analyzed single contingency conditions under two different HVDC terminal interconnection configurations, one with the new HVDC terminal operating separately to the existing HVDC terminal and the other with the new HVDC terminal tied to the existing HVDC terminal. These analyses were performed to determine whether the two HVDC terminals (new and existing) should be tied together or operated independently of each other for system reliability reasons. The concern of tying the two terminals together was whether either of the two lines coming out of Artesia (Amrad- Artesia 345 kv line or the new Artesia-Caliente 345 kv line) could handle up to 400 MW of power flow in the event of the loss of the other 345 kv line. These analyses determined that both lines could handle the increased power flow in the event that the other line was lost with no criteria violations and that tying the two terminals together will provide the best scenario for providing the greatest reliability to the system. This Facilities Study For Proposed HVDC Terminal 5 El Paso Electric Company

10 configuration also improves system reliability in the event of a Caliente-Amrad 345 kv line outage. Therefore, all subsequent cases were analyzed using the configuration with the two HVDC terminals tied together. Given that the power imported from the proposed project will be modeled to serve EPE s native load, only impacts to EPE s system were noted in this study. The evaluation process in studying these impacts included powerflow, Delta V, Q-V reactive margin, and transient stability analyses. All recommended modifications needed to correct the impacts on the EPE system due to the proposed project and their corresponding estimated costs were noted in this report. It must also be noted that this study was not meant to analyze every scenario that may occur on the EPE system. This study analyzed the boundaries around which the EPE system can operate, under the scenarios agreed to by EPEGD and EPE T&D. Results of the analyses indicate that two criteria violations will occur to the existing EPE system when the proposed project is interconnected to the EPE transmission system. Overload criteria violations were found on the Caliente and Arroyo 345/115 kv autotransformers during single contingency conditions. Utilizing study results and engineering judgment, proposed system modifications and estimated costs for these modifications were made to correct these criteria violations. Further evaluation of the system with the recommended modifications installed was performed to insure that the recommended modifications will relieve all impacts observed in the scenarios analyzed. 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 1). This analysis was performed using the GE PSLF program. For pre-contingency solutions, transformer tap phase-shifting transformer angle movement, static Var device switching and area interchange control were allowed. For each contingency studied, all regulating equipment (transformer controls and switched shunts) were fixed at precontingency positions. All buses, lines, and transformers in the El Paso control area with base voltages of 69 kv and above were monitored. Pre-contingency flows on EPE s network elements must remain at or below the normal rating of the element, and post-contingency flows on network elements must remain at or below the emergency rating. Flows above 100% of an element s rating are considered overload criteria violations. The minimum and maximum allowed voltages are specified in EPE s latest FERC Form 715. Any voltage which did not meet criteria in the benchmark cases (without the proposed HVDC terminal interconnection) was considered an exception to the criteria for that specific bus and did not have a penalizing effect when evaluating the interconnection. Facilities Study For Proposed HVDC Terminal 6 El Paso Electric Company

11 The criteria used in monitoring the EPE bus voltages are shown in Table 2-1. Area EPE Table 2.1: Voltage Performance Criteria. Conditions Normal Contingency Loading Limit < Normal Rating < Emergency Rating Voltage (p.u.) Maximum Volt. Drop () Comments kV and above Artesia 345 kv Arroyo 345 kv PS source side Alamo, Sierra Blanca and Van Horn 69kV kv to 115 kv % Artesia 345kV % Arroyo 345kV PS source side Alamo, Sierra Blanca and Van Horn 69kV % Hidalgo, Luna, or other 345 kv buses It should be noted that the voltage drop criteria is specified as a percentage of the precontingency voltage. For example, if the pre-contingency voltage at a specific 345kV bus is pu, and the voltage drops to pu during the contingency, the voltage drop would be 7%, calculated as: = ((Vpre-Vpost) Vpre) x 100% = (( ) 1.030) x 100% = ( ) x 100% = 7.0% Voltage Violation Criteria The voltage criteria used in this study are shown in Table 2.1 above. In general, all bus voltages 69 kv and above during All Lines In Service (ALIS) conditions must have per unit voltages between 0.95 and 1.05 pu and between and 1.05 pu during single contingency (N-1) conditions. There are some exceptions to these criteria and are noted in Table Loading Violation Criteria The loading criteria used in this Study are based on WECC loading criteria. An element (transmission line, transformer) cannot be loaded to over 100% of its continuous/normal rating for an ALIS condition. During N-1 contingency conditions, the element many not exceed 100 % of its emergency rating. Facilities Study For Proposed HVDC Terminal 7 El Paso Electric Company

12 3.0 METHODOLOGY 3.1 Assumptions The following assumptions are consistent for all study scenarios unless otherwise noted. Project dollar amounts shown are in 2004 U.S. dollars. The cost of the proposed project and associated equipment (i.e. HVDC terminal and associated SVC) is separate and not included in this study. This study assumes that EPE substation space is available for the system recommended modifications. The cost estimates provided here include material, labor, and overhead costs for installing new equipment. This study does not analyze any transmission service from the interconnection point to any point on the grid. The study only determined modifications needed to deliver the proposed HVDC terminal output to the interconnection point (Caliente 345 kv Substation) for the purpose of serving native load. 3.2 Procedure As previously mentioned, the analyses performed in this study include Powerflow, Delta V, Q-V, and Transient Stability Analyses. Detailed discussions for each topic have been included in this report (for quick reference of any topic, refer to the Table of Contents). The following is a description of the procedures used to complete the analyses Base Case Development and Description of Cases Four cases, each representing the 2008 and 2013 Heavy Summer (HS) and Light Winter (LW) seasons were modeled in these analyses. Descriptions of the cases analyzed are listed below: Case 1: Case with the proposed HVDC terminal modeled to provide 50 MW of power into EPE s system. Case 2: Case with the proposed HVDC terminal modeled to provide 100 MW of power into EPE s system. Case 3: Case with the proposed HVDC terminal modeled to provide 150 MW of power into EPE s system. Case 4: Case with the proposed HVDC terminal modeled to provide 200 MW of power into EPE s system. Facilities Study For Proposed HVDC Terminal 8 El Paso Electric Company

13 Each of the cases described above was analyzed in the 2008 HS and 2013 HS and LW seasons. In order to determine which impacts resulted from the proposed HVDC terminal interconnection, each case was analyzed both with and without the HVDC terminal representation. Power output levels of between 50 MW and 200 MW were modeled for the HVDC terminal as described in the description of cases above. Base cases were developed for each case (Cases 1-4), simulating the system with all lines in service and without the proposed HVDC terminal. Single contingency powerflow analyses were then performed on these cases to identify any existing system impacts without the proposed project. Voltage and/or loading criteria violations in the EPE area were noted and corrected in these cases. The four Base Cases without the proposed HVDC terminal were then used to develop cases which included the HVDC terminal at various power output levels ranging from 50 Mw to 200 MW. Single contingency powerflow analyses were then performed on these cases. The cases with the new HVDC terminal were then compared against the cases without the new HVDC terminal to determine the impacts due to the proposed interconnection project Powerflow Analysis Once the base cases were developed for each of the 2008 and 2013 HS and LW seasons, powerflow single contingency analyses were performed. The same contingencies were evaluated for all cases and are identified in Appendix 3. Based on engineering judgment, these contingencies were selected because they are the ones most likely to stress the EPE system. Contingencies in the areas of neighboring utilities were not analyzed because the proposed generation will be used to serve native load and thus should only affect the EPE area. Contingency powerflow analyses table results can be found in Appendix Delta V Analysis Delta V () studies were performed with the proposed HVDC terminal interconnection modeled. Pre-contingency and post-contingency voltages were measured at various EPE 345 kv buses to determine if the voltage drop or from a pre contingency to a post-contingency condition did not violate the EPE voltage criteria as described in Table 2.1 shown in Section 2.1 of this report. The is calculated using the following equation: = (Vpre-Vpost) / Vpre x 100% Tables listing the analyses for all the cases can be found in Appendix 5. Facilities Study For Proposed HVDC Terminal 9 El Paso Electric Company

14 3.2.4 Q-V Analysis Q-V analyses were performed on the 2008 and 2013 HS and LW cases to verify that the WSCC 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, EPE s 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 WSCC 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. However, for this study, three other contingencies were analyzed in the area of the proposed project to determine the worst contingency. Q-V analyses were performed for the 2008 HS and 2008 LW Case 1 scenarios for outages of the Caliente-Artesia2 (proposed line), Artesia-Amrad, and Amrad-Artesia 345 kv lines. These analyses determined that the Caliente2-Artesia 345 kv line contingency was the worst contingency. Therefore, this contingency was used to evaluate reactive power margins for all the remaining cases. Q-V plots were created showing the margins available at the Arroyo 345 kv, Caliente 345 kv, Diablo 345 kv, Luna 345 kv, and Newman 345 kv buses. Plots showing the results of the Q-V analyses can be found in Appendix Transient Stability Analysis The stability data representation for the EPEGD proposed HVDC terminal and corresponding SVC device were based on data found in the WECC stability data base. The SPS Blackwater HVDC terminal data was used as an approximation to simulate the proposed HVDC terminal and the SVC device. EPE used these generic equivalent models for the HVDC terminal and SVC device components. Since the specific devices that will be used for this proposed HVDC terminal have not been determined yet, these generic models were used as the best data available to complete the study. The models were then represented in the WECC master stability file (dated 3/16/04) for use in the GE Transient Stability Program. Transient stability analyses were conducted on all 2008 and 2013 HS and LW cases. Plots showing the results of the Transient Stability analyses can be found in Appendix 7. Facilities Study For Proposed HVDC Terminal 10 El Paso Electric Company

15 4.0 POWER FLOW ANALYSIS RESULTS The four cases described in section of this report were developed for use in this analysis. Each of the four cases was developed to represent the 2008 and 2013 Heavy Summer (HS) and Light Winter (LW) seasons. These cases represent four scenarios in which the EPE system may operate with the interconnection of the proposed HVDC terminal at various output levels. The table below shows transmission loadings with the proposed HVDC terminal interconnection for the 2008 HS cases. Once the overloads were corrected in the 2008 HS cases, no other overloads were found in the 2008 LW, 2013 HS, or 2013 LW cases HS TRANSMISSION FACILITY OVERLOADS CASE # CONTINGENCY OVERLOADED ELEMENT PERCENT LOADING * 1 Caliente 115/345 kv transformer #1 Caliente 115/345 kv transformer # Caliente 115/345 kv transformer #1 Caliente 115/345 kv transformer # Luna-Diablo 345 kv line Arroyo 115/345 kv transformer Anthony-Newman 115 kv line Arroyo 115/345 kv transformer Amrad 115/345 kv transformer Arroyo 115/345 kv transformer Caliente 115/345 kv transformer #1 Caliente 115/345 kv transformer # Luna-Diablo 345 kv line Arroyo 115/345 kv transformer Anthony-Newman 115 kv line Arroyo 115/345 kv transformer Amrad 115/345 kv transformer Arroyo 115/345 kv transformer Caliente 115/345 kv transformer #1 Caliente 115/345 kv transformer # Luna-Diablo 345 kv line Arroyo 115/345 kv transformer Anthony-Newman 115 kv line Arroyo 115/345 kv transformer Amrad 115/345 kv transformer Arroyo 115/345 kv transformer Notes: * Percent loadings are based on the element s emergency rating. As can be seen from the tables above, one of the Caliente autotransformers experiences a criteria violation during an outage of the second Caliente autotransformer and the Arroyo autotransformer experiences criteria violations during each of three single contingency conditions. Therefore, the following system modifications are recommended in order to eliminate these criteria violations: 1. Add 2 nd Arroyo 115/345 kv auto transformer in Add 3 rd Caliente 115/345 kv auto transformer in 2008 Facilities Study For Proposed HVDC Terminal 11 El Paso Electric Company

16 Making these system improvements eliminates the criteria violations shown above for all other cases (2008 LW, 2013 HS, and 2013 LW) in this study. No other criteria violations were found in any of the other cases after these modifications were made. Please note that these analyses assume that the proposed HVDC terminal will be interconnected to the EPE system through a new 345 kv line from the new HVDC terminal at Artesia to EPE s Caliente 345 kv Substation. As such, the new line, the associated modifications needed to connect this line to the substations (Caliente and Artesia2), and the line reactors required for line switching, must be included as part of the system improvements to allow the interconnection of the proposed HVDC terminal and the importation of up to 200 MW of additional power into the EPE transmission system. These analyses also assume that the proposed HVDC terminal is tied together with the existing HVDC terminal as described in Section 2.0 above. Below are tables which show the flows and percent loadings of elements in the Amrad- Artesia area during single contingency outages of the new Caliente-Artesia and the existing Caliente-Amrad 345 kv lines in the 2008 HS and 2013HS Case 4 scenarios with the above system modifications included HS CASE 4 ELEMENT LOADINGS DURING CALIENTE-ARTESIA 345 KV LINE OUTAGE ELEMENT FLOW (MVA) % LOADING Amrad-Artesia 345 kv line Amrad 345/115 kv autotransformer Caliente-Amrad 345 kv line Caliente 345/115 kv autotransformer(s) HS CASE 4 ELEMENT LOADINGS DURING AMRAD-ARTESIA 345 KV LINE OUTAGE ELEMENT FLOW (MVA) % LOADING Caliente-Artesia2 345 kv line Amrad 345/115 kv autotransformer Caliente-Amrad 345 kv line Caliente 345/115 kv autotransformer(s) HS CASE 4 ELEMENT LOADINGS DURING CALIENTE-ARTESIA 345 KV LINE OUTAGE ELEMENT FLOW (MVA) % LOADING Amrad-Artesia 345 kv line Amrad 345/115 kv autotransformer Caliente-Amrad 345 kv line Caliente 345/115 kv autotransformer(s) Facilities Study For Proposed HVDC Terminal 12 El Paso Electric Company

17 2013 HS CASE 4 ELEMENT LOADINGS DURING AMRAD-ARTESIA 345 KV LINE OUTAGE ELEMENT FLOW (MVA) % LOADING Caliente-Artesia2 345 kv line Amrad 345/115 kv autotransformer Caliente-Amrad 345 kv line Caliente 345/115 kv autotransformer(s) As can be seen from the tables above, there are no additional criteria violations during outages of the new Caliente-Artesia 345 kv line or the Amrad-Artesia 345 kv line when the system improvements recommended above are made. Additionally, no voltage criteria violations were found during these contingencies because the Static Var Compensating (SVC) device located at the proposed HVDC terminal provides adequate VAR support during the contingencies. Therefore, the EPE system can handle an outage of the proposed Caliente-Artesia 345 kv line without the need for any additional system improvements other than the ones listed above. It should be noted that the costs associated with the design and construction of the new HVDC terminal have not been included in this study. The study assumes that the proposed HVDC terminal will be designed to include an SVC device to regulate voltage levels in the area. Delta-V, Q-V, and Transient Stability analyses indicate that the transmission system will require this SVC device to have a range of at least 50 capacitive (MVAC) and 130 reactive (MVAR) to maintain voltage stability during single contingency conditions. However, more detailed analyses will need to be performed in order to determine the exact size of this device. The study also assumes that the new terminal will be designed to provide 100% load factor correction. Please refer to Appendix 2 for the powerflow maps of these analyses and to Appendix 4 for the tables showing the criteria violations found during these contingency analyses. Facilities Study For Proposed HVDC Terminal 13 El Paso Electric Company

18 5.0 DELTA V ANALYSIS RESULTS A delta V () analysis was performed on all 2008 and 2013 HS and LW cases with the proposed HVDC terminal interconnection modeled. Pre-contingency and postcontingency voltages were measured at various EPE 345 kv buses to determine if the voltage drop or from a pre contingency to a post-contingency condition does not violate the EPE voltage criteria as described in Table 2.1 shown in Section 2.1 of this report. The is calculated using the following equation: = (Vpre-Vpost) / Vpre analyses were performed for single contingencies of the three 345 kv lines that will cause the greatest impact with the proposed project on the EPE system. The analyses were performed on the Caliente-Artesia2, Caliente-Amrad, and Amrad-Artesia 345 kv lines. The tables below show the results of the analyses with the greatest for some of the 345 kv and 115 kv buses in the area. BASE VOLT 2008 HS CASE 1 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2008 HS CASE 2 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2008 HS CASE 3 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN Facilities Study For Proposed HVDC Terminal 14 El Paso Electric Company

19 BASE VOLT 2008 HS CASE 4 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2008 LW CASE 1 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2008 LW CASE 2 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE V OUTAGE V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2008 LW CASE 3 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V * BUS AMRAD CALIENTE * AMRAD ALAMOTAP HOLLOMAN * The at the Caliente 345 kv bus was above the 7% limit. This was corrected by increasing the range on the capacitive side of the proposed SVC at the HVDC terminal from 0 MVAC to 25 MVAC. Facilities Study For Proposed HVDC Terminal 15 El Paso Electric Company

20 BASE VOLT 2008 LW CASE 4 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE * OUTAGE V V AMRAD-ART OUTAGE V * * BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN * The analysis of the for this case assumes the same SVC range used in the 2008 LW Case 3 scenario. BASE VOLT 2013 HS CASE 1 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2013 HS CASE 2 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2013 HS CASE 3 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN Facilities Study For Proposed HVDC Terminal 16 El Paso Electric Company

21 BASE VOLT 2013 HS CASE 4 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2013 LW CASE 1 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2013 LW CASE 2 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE OUTAGE V V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN BASE VOLT 2013 LW CASE 3 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE V OUTAGE V AMRAD-ART OUTAGE V BUS AMRAD CALIENTE * AMRAD ALAMOTAP HOLLOMAN * The at the Caliente 345 kv bus was above the 7% limit. This was corrected by increasing the range on the capacitive side of the proposed SVC at the HVDC terminal from 0 MVAC to 50 MVAC. Facilities Study For Proposed HVDC Terminal 17 El Paso Electric Company

22 BASE VOLT 2013 LW CASE 4 ANALYSIS CAL-ART2 CAL-AMRAD OUTAGE V * OUTAGE V AMRAD-ART OUTAGE V * * BUS AMRAD CALIENTE AMRAD ALAMOTAP HOLLOMAN * The analysis of the for this case assumes the same SVC range used in the LW Case 3 scenario. As stated in EPE s FERC Form 715 Transmission Planning Reliability Criteria, (Appendix 1) EPE s post disturbance post-transient voltage drop () must not exceed 7% at the Hidalgo 345 kv, Luna 345 kv, or any EPE 345 kv buses. Results of these analyses indicate that the criteria violations experienced in the 2008 and 2013 LW Case 3 and Case 4 scenarios can be corrected by increasing the capacitive range of the SVC device. These analyses determined that the SVC device required as part of the HVDC terminal design will need to have a range of at least 25 MVAC to 130 MVAR in 2008 and 50 MVAC to 130 MVAR in Again, more detailed analyses will have to be performed in order to determine the exact size of this SVC device. Please refer to Appendix 5 for the tables showing the results of the analyses. Facilities Study For Proposed HVDC Terminal 18 El Paso Electric Company

23 6.0 Q-V ANALYSIS RESULTS Q-V analyses are conducted in order to verify that the scenarios, which include the interconnection of the proposed HVDC terminal, comply with the WECC Voltage Stability Criteria. Q-V analysis provides a way to investigate the potential for voltage collapse during the post-transient period within 3 minutes after the disturbance. Q-V analyses were performed for all cases in this Study. A procedure developed by WECC is used to determine the reactive power margin. As outlined in this 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 the Luna-Diablo (LD) 345 kv line. However, for this study, three additional contingencies were analyzed in the vicinity of the proposed project to determine if any of them would cause more of an impact than the LD outage. Q-V analyses were performed on the 2008 HS and 2008 LW Case 1 scenarios for an outage of the Caliente-Artesia2 (proposed line), Artesia-Amrad, and Amrad-Artesia 345 kv lines. These analyses determined that the Caliente2-Artesia 345 kv line contingency was the worst contingency which impacted the reactive power margin. Therefore, this contingency was used to evaluate reactive power margins for all the remaining cases to verify that EPE reactive power margins are in compliance with the WECC criteria. Q-V analyses were conducted for the 2008 and 2013 HS and LW system load configurations. EPE 345 kv buses monitored included Arroyo, Caliente, Diablo, Luna, and Newman 345 kv buses. EPE 115 kv buses monitored included the Amrad, Holloman, White Sands, Caliente, and Alamogordo 115 kv buses. Resulting plots and reactive power margins of the analyses can be found in Appendix 6. Following are the results of the Q-V analysis. The tables that follow show the reactive power margins available and the most critical bus in each case. Please note that a negative number indicates that there is sufficient reactive power to meet WSCC criteria and a positive number indicates that the system is deficient in reactive power and does not meet the criteria Case 1 The 2008 HS and LW Case 1 scenarios simulated the existing EPE system with the proposed HVDC terminal interconnection. As outlined in the WECC procedure for determining reactive power margin, EPE s load was increased by 5% and the worst contingency was analyzed. The margin was determined by identifying the critical Facilities Study For Proposed HVDC Terminal 19 El Paso Electric Company

24 (weakest) bus on the system during the worst contingency. This case was modeled with the HVDC terminal output at 50 MW. The following table shows the results of the 2008 HS and LW Case 1 analyses. Available reactive margins for the critical buses on both the 345 kv and 115 kv systems during a Caliente-Artesia2 (CA) 345 kv line contingency are shown below Case 1 Available Reactive Margin during CA 345 kv Outage System Condition MVAR Margin Critical Bus 2008 HS 345 kv Caliente 345 kv 2008 HS 115 kv Holloman 115 kv 2008 LW 345 kv Caliente 345 kv 2008 LW 115 kv Amrad 115 kv As can be seen in the above table, there were no reactive power margin deficiencies in either of the two 2008 Case 1 scenarios analyzed. The 345 kv Q-V reactive power margin plots for the 2008 HS and LW Case 1 scenarios can be found on pages 1-2 and the 115 kv Q-V reactive power margin plots for these scenarios can be found on pages of Appendix Case 2 The 2008 HS and LW Case 2 scenarios simulated the existing EPE system with the proposed HVDC terminal interconnection. As outlined in the WECC procedure for determining reactive power margin, load was increased by 5% and the worst contingency was analyzed. The margin was determined by identifying the critical (weakest) bus on the system during the worst contingency. This case was modeled with the HVDC terminal output at 100 MW. The following table shows the results of the 2008 HS and LW Case 2 analyses. Available reactive margins for the critical buses on both the 345 kv and 115 kv systems during a CA 345 kv line contingency are shown below Case 2 Available Reactive Margin during CA 345 kv Outage System Condition MVAR Margin Critical Bus 2008 HS 345 kv Caliente 345 kv 2008 HS 115 kv Holloman 115 kv 2008 LW 345 kv Caliente 345 kv 2008 LW 115 kv Holloman 115 kv As can be seen in the above table, there were no reactive power margin deficiencies in either of the two 2008 Case 2 scenarios analyzed. The 345 kv Q-V reactive power margin plots for 2008 HS and LW Case 2 scenarios can be found on pages 3-4 and the 115 kv Q-V reactive power margin plots for these scenarios can be found on pages of Appendix 6. Facilities Study For Proposed HVDC Terminal 20 El Paso Electric Company

25 Case 3 The 2008 HS and LW Case 3 scenarios simulated the existing EPE system with the proposed HVDC terminal interconnection. As outlined in the WECC procedure for determining reactive power margin, load was increased by 5% and the worst contingency was analyzed. The margin was determined by identifying the critical (weakest) bus on the system during the worst contingency. This case was modeled with the HVDC terminal output at 150 MW. The following table shows the results of the 2008 HS and LW Case 3 analyses. Available reactive margins for the critical buses on both the 345 kv and 115 kv systems during a CA 345 kv line contingency are shown below Case 3 Available Reactive Margin during CA 345 kv Outage System Condition MVAR Margin Critical Bus 2008 HS 345 kv Caliente 345 kv 2008 HS 115 kv Holloman 115 kv 2008 LW 345 kv Caliente 345 kv 2008 LW 115 kv Holloman 115 kv As can be seen in the above table, there were no reactive power margin deficiencies in either of the two 2008 Case 3 scenarios analyzed. The 345 kv Q-V reactive power margin plots for 2008 HS and LW Case 2 scenarios can be found on pages 5-6 and the 115 kv Q-V reactive power margin plots for these scenarios can be found on pages of Appendix Case 4 The 2008 HS and LW Case 4 scenarios simulated the existing EPE system with the proposed HVDC terminal interconnection. As outlined in the WECC procedure for determining reactive power margin, load was increased by 5% and the worst contingency was analyzed. The margin was determined by identifying the critical (weakest) bus on the system during the worst contingency. This case was modeled with the HVDC terminal output at 200 MW. The following table shows the results of the 2008 HS and LW Case 4 analyses. Available reactive margins for the critical buses on both the 345 kv and 115 kv systems during a CA 345 kv line contingency are shown below Case 4 Available Reactive Margin during CA 345 kv Outage System Condition MVAR Margin Critical Bus 2008 HS 345 kv Caliente 345 kv 2008 HS 115 kv Holloman 115 kv 2008 LW 345 kv Caliente 345 kv 2008 LW 115 kv Holloman 115 kv Facilities Study For Proposed HVDC Terminal 21 El Paso Electric Company

26 As can be seen in the above table, there were no reactive power margin deficiencies in either of the two 2008 Case 4 scenarios analyzed. The Q-V margin determined in the 2008 LW Case 4 scenario assumed that the SVC device at the proposed HVDC terminal will have a range of 25 MVAC to 130 MVAR. The 2008 HS Case 4 scenario margin was determined based on an SVC range of 0 MVAC to 130 MVAR. As stated previously, more detailed studies will be needed in order to determine the exact size of the SVC device. The 345 kv Q-V reactive power margin plots for 2008 HS and LW Case 2 scenarios can be found on pages 7-8 and the 115 kv Q-V reactive power margin plots for these scenarios can be found on pages of Appendix Case 1 The 2013 HS and LW Case 1 scenarios simulated the existing EPE system with the proposed HVDC terminal interconnection. As outlined in the WECC procedure for determining reactive power margin, load was increased by 5% and the worst contingency was analyzed. The margin was determined by identifying the critical (weakest) bus on the system during the worst contingency. This case modeled a 2013 load pattern and the HVDC terminal output at 50 MW. The following table shows the results of the 2013 HS and LW Case 1 analyses. Available reactive margins for the critical buses on both the 345 kv and 115 kv systems during a CA 345 kv line contingency are shown below Case 1 Available Reactive Margin during CA 345 kv Outage System Condition MVAR Margin Critical Bus 2013 HS 345 kv Caliente 345 kv 2013 HS 115 kv Holloman 115 kv 2013 LW 345 kv Caliente 345 kv 2013 LW 115 kv Holloman 115 kv As can be seen in the above table, there were no reactive power margin deficiencies in either of the two 2013 Case 1 scenarios analyzed. The Q-V margin determined in the 2013 LW Case 1 scenario assumed that the SVC device at the proposed HVDC terminal would have a range of 50MVAC to 130 MVAR. The 2013 HS Case 1 scenario margin was determined based on an SVC range of 0 MVAC to 130 MVAR. As stated previously, more detailed studies will be needed in order to determine the exact size of the SVC device. The 345 kv Q-V reactive power margin plots for 2008 HS and LW Case 2 scenarios can be found on pages 9-10 and the 115 kv Q-V reactive power margin plots for these scenarios can be found on pages of Appendix 6. Facilities Study For Proposed HVDC Terminal 22 El Paso Electric Company