XXXXXXXXXXXXXXXX Transmission Interconnection Feasibility Study

Transcription

1 XXXXXXXXXXXXXXXX Transmission Interconnection Feasibility Study System Operations Department System Planning Section March 2002

2 Table of Contents: 1.0 EXECUTIVE SUMMARY COST ESTIMATES Cost estimate for Scenario #1 & #2 (sale From SPS to WSCC) Cost estimate for Scenario #3 & #4 (sale From WSCC to SPS) Cost estimate for Scenario #5 (sale From EPE to SPS) INTRODUCTION ASSUMPTIONS CRITERIA PROCEDURE Benchmark and Base Case Development List of Contingencies Taken in Each Scenario QV Reactive Margin Analysis MODELING HVCS TERMINAL POWERFLOW and QV ANALYSES Results Scenario # Benchmark analysis Power Flow analysis: QV analysis: Comparison analysis Power Flow analysis: QV analysis: Final Analysis for Scenario # Scenario # Benchmark analysis Power Flow analysis: QV analysis: Comparison analysis Power Flow analysis: QV analysis: Final Analysis for Scenario # Scenario # Benchmark analysis Power Flow analysis: QV analysis: Comparison analysis Power Flow analysis: QV analysis: Final Analysis for Scenario # Scenario # Benchmark analysis Power Flow analysis: QV analysis: 30 Feasibility Study - Page 2 - El Paso Electric Company

3 Comparison analysis Power Flow analysis: QV analysis: Final Analysis for Scenario # Scenario # Benchmark analysis Comparison analysis Power Flow analysis: QV analysis: Final Analysis for Scenario # DISCLAIMER CERTIFICATION APPENDICES: 38 Appendix 1: Feasibility Study: Study Scope 39 Appendix 2: EPE FERC Form Appendix 3: Powerflow Maps One-Line Diagrams 41 Appendix 4: Contingencies List 42 Appendix 5: Base Case, Contingencies & QV, Reactive Margin Study Results 43 Feasibility Study - Page 3 - El Paso Electric Company

4 1.0 EXECUTIVE SUMMARY In accordance with the Request for Study dated April 27, 2001, El Paso Electric Company (EPE) and XXXXXXXXXXXXXXXXXXXXXXXXXXXX (XXX) signed an Agreement for a Feasibility Transmission/Generation Interconnection Study on June 20, On January 7, 2002, XXX and EPE signed the Feasibility High Voltage Converter Station Study: STUDY SCOPE (Scope) (Appendix 1). In this Study, XXX requested EPE perform a preliminary analysis that evaluates XXX s proposed construction and interconnection of a 200 MW High Voltage Converter Station (HVCS) located at the existing High Voltage Direct Current (HVDC) terminal at Artesia 345 kv substation in Artesia, New Mexico. The main goal of this analysis was to investigate the potential problems that may arise from the construction and operation of a 200 MW HVCS terminal in parallel with the existing 220 MW HVDC terminal and to evaluate the magnitude of the EPE transmission system modification and costs that may arise from this project. The proposed HVCS station consists of two 100 MW units in parallel with the existing 220 MW HVDC terminal. These units were analyzed for the study year of 2003 only, at the request of XXX. Also, it was requested by XXX that the preliminary analysis would include only the power flow and QV (reactive margin) evaluations. Additionally, this study was not meant to analyze every operating scenario. This study analyzes only the primary boundaries around which the EPE system operates under the transmission scenarios agreed to between EPE and XXX. It will, therefore, give the parameters in which the system, with the XXX terminals included, will operate and most of the required EPE system modifications that will allow operation at those boundaries. However, this study is not meant to investigate all of the potential impacts that may be caused by the HVCS terminal installation and therefore can t guaranty that the list of the required modifications is complete. Additional studies will be required should XXX decide to proceed to the next step. The verbal communications with XXX and the Study Scope were used as guides by EPE to perform the system studies, which included power flow and Q-V reactive margin analysis only. No transient analysis, short circuit or any other types of switching and/or harmonics analysis were performed at this time. Additionally, no evaluation of the impacts to the existing HVDC terminal with the proposed HVCS was performed. It should be noted that the original Study Scope for this study included several scenarios with 80 MW of generation located at the Artesia 345 kv Bus. This generation was anticipated to be located in close proximity to the proposed HVCS terminal. However, since the signing of the Study Scope, the construction of this plant was canceled. Hence, all cases that included the proposed 80 MW generator were omitted from this study report. Results of this analysis indicate that the addition of the proposed 200 MW HVCS terminal has severe impacts on the EPE transmission system and as a result required Feasibility Study - Page 4 - El Paso Electric Company

5 extensive transmission upgrades. It should be noted, however, that not all of the upgrades and additions that are proposed in this feasibility analysis report may be necessary. This is due to the fact that since some of the proposed upgrades are quite significant and will therefore change system power flows, these upgrades may eliminate the need for some of the other called for upgrade. This evaluation was not made since, pursuant to the feasibility scope, the modifications were not tested for validity.. Therefore, a very careful consideration of these impacts is required in a future facilities study. The future facilities study will investigate these issues in a step by step procedure. As stated above, that the nature of this feasibility study doesn t provide for a detailed analysis of all available modification options. Engineering judgement and common sense were used to select the proposed modifications. For instance the additional new Amrad-Caliente 345 kv transmission line was thought as a better alternative in comparison to the upgrade of Amrad-Newman 115 kv path for the reason of total cost (proposed new 345 kv line versus upgrade of four 115 kv transmission lines and new Amrad 345/115 autotransformer). Another consideration was that some of the 115 kv lines in the Amrad-Newman path are situated on military land and right of way issues may be very difficult to resolve. Future studies may, also, introduce alternative projects that may eliminate the need in the projects proposed in this analysis. For instance the second Newman-Caliente 345 kv transmission line may be thought as a better alternative to numerous upgrades in the 115/69 kv systems proposed in scenarios #3, #4 & #5. The other possibility is a new 345 kv transmission line from Amrad to Newman. This study shows that the largest impacts result from the scenarios modeling the contingency of Amrad-Caliente or Newman-Caliente 345 kv transmission lines. EPE s Diablo, Arroyo, Caliente and Luna 345/115 kv autotransformers were loaded above their emergency ratings during various transmission system contingencies. The overloading of EPE autotransformers can be attributed to the shift in the power flows caused by the addition of the proposed HVCS terminal. For the study year 2003, necessary upgrades include upgrades and construction of several transmission lines. The final choice of the transmission lines that need to be built and/or upgraded will be determined in the facilities analysis. This report includes rough cost estimates for the upgrades and additions proposed in this study. Scenarios modeling sales from EPE/WSCC to SPS show the worst EPE system impacts. This is due to the fact that the EPE transmission system was not designed for large power flow transfers in the eastern direction (from WSCC/EPE to SPS). Normally power flow is scheduled in the western direction (from SPS to WSCC/EPE). At the present time the EPE and SPS transmission systems are connected through a single Artesia-Amrad- Caliente-Newman 345 kv link and, in case of contingency of Amrad-Caliente or Newman-Caliente 345 kv transmission lines, all of the flow through this link find its way through the existing 115 kv system. The current power flow distribution from EPE generation and import from WSCC counter-flows the power flowing from SPS. This Feasibility Study - Page 5 - El Paso Electric Company

6 results in a stable and uniformly loaded EPE transmission system. With the reversal of flows to the eastern (to SPS) direction, power flow distribution changes resulting in a number of overloads. Many of the overloads found as a result of addition of the proposed HVCS terminal are in excess of the emergency rating of the element and therefore require an upgrade of the overloaded element. A list of the transmission lines that need to be built or upgraded is dependent on the scenario in consideration. The complete list of transmission line upgrades proposed in this study is presented below: New, second Amrad-Caliente 345 kv transmission line Upgrade of Mesa-Rio Grande 115 kv transmission line Upgrade of Sunset North-Rio Grande 115 kv transmission line Upgrade of Ascarate-Cooper 115 kv transmission line Upgrade of Austin North-Chevron SO 115 kv transmission line Upgrade of Ascarate-Chevron 115 kv transmission line Upgrade of Chevron-Chevron SO 115 kv transmission line Upgrade of Lane-Cooper 115 kv transmission line Upgrade of Newman-Vista 69 kv transmission line Upgrade of Dyer-Austin 69 kv transmission line Upgrade of Santa Fe-Subset 69 kv transmission line Additionally, as mentioned above, 200 MVA 345/115 kv autotransformers need to be added at Diablo, Arroyo, Luna and Caliente substations. Some extensive bus work and substation modifications will be required in order to complete these additions. Undervoltages that may be caused by the addition of HVCS terminal may need to be investigated in more details in the facilities study. This is due to a fact that the voltage situation in the Amrad 345 kv substation area becomes more complicated with the addition of the proposed HVCS terminal. In order to study voltages in this area, a better representation of HVCS terminal is required. Coincidentally, a power flow model of the proposed HVCS terminal will be available with the PSLF release 13 in February/March At that time XXX will be required to provide the necessary data for the HVCS terminal. Feasibility Study - Page 6 - El Paso Electric Company

7 Results of this study show that for EPE to continue to operate reliably and meet required WSCC criteria under the scenarios studied, system modifications would be required for it s the EPE system. The list of EPE system modifications, with estimated costs is dependent on the scenario in consideration. The range of scenario/cost varies between $17,642,000 for Scenarios #5 and $32,875,000 for scenario #3 & #4. These cost estimates may change upon completion of a facilities analysis. Please note that the impacts of the XXX s HVCS terminal on the neighboring utilities was not covered in this analysis. The loading and voltage problems for these utilities were monitored and are available in the Appendices to this study. The costs of the upgrades that may be necessary in order to ensure the reliability of these systems were not considered however in this analysis. Also, this analysis does not include any of the XXX s costs associated with design and construction of the HVCS terminal, required 345 kv Substation, and tap into the existing EPE 345 kv system at Artesia. Feasibility Study - Page 7 - El Paso Electric Company

8 2.0 COST ESTIMATES The following rough capital cost estimates are for various modifications to the EPE system required for XXX to interconnect 200 MW HVCS terminal in 2003 time frame. These rough costs are estimates only at this time using as a basis the information about the XXX Project as supplied by XXX. Project dollar amounts shown are in year 2002 U.S. dollars. 2.1 Cost estimate for Scenario #1 & #2 (sale From SPS to WSCC) FACILITY MODIFICATIONS COST * 1a. Additional auto transformer (200 MVA) at Arroyo $1.800 million 1b. 345 kv & 115 kv breakers w/structures, switches, bus work at Arroyo $1.700 million Subtotal: $3.500 million 2a. Additional (200 MVA) auto transformer at Caliente $1.800 million 2b. 345 kv & 115 kv breakers w/structures, switches, bus work at Caliente $2.212 million Subtotal: $4.012 million 3. A new Amrad-Caliente 345 kv transmission line $ million Subtotal: $ million Totals: $ million * - Labor and benefits costs normally estimated at 25% of capital costs have not been included. 2.2 Cost estimate for Scenario #3 & #4 (sale From WSCC to SPS) FACILITY MODIFICATIONS COST * 1a. Additional auto transformer (200 MVA) at Arroyo $1.800 million 1b. 345 kv & 115 kv breakers w/structures, switches, bus work at Arroyo $1.700 million Subtotal: $3.500 million 2a. Additional (200 MVA) auto transformer at Diablo $1.800 million 2b. 345 kv & 115 kv breakers w/structures, switches, Feasibility Study - Page 8 - El Paso Electric Company

9 bus work at Diablo Subtotal: $1.650 million $3.450 million 3a. Additional (200 MVA) auto transformer at Luna $1.800 million 3b. 345 kv & 115 kv breakers w/structures, switches, bus work at Luna $2.700 million Subtotal: $4.500 million 4. A new Amrad-Caliente 345 kv transmission line $ million Subtotal: $ million 5. Mesa-Rio Grande 115 kv line upgrade $0.440 million 6. Sunset N-Rio Grande 115 kv line upgrade $1.020 million 7. Austin North-Chevron So 115 kv line upgrade $0.384 million 3. Newman-Vista 115 kv line upgrade $4.996 million 4. Ascarate-Copper 115 kv line upgrade $0.424 million 5. Ascarate-Chevron 115 kv line upgrade $0.110 million 6. Chevron-Chevron So 115 kv line upgrade $0.242 million 7. Lane-Cooper 115 kv line upgrade $1.122 million 8. Santa Fe-Sunset 69 kv line upgrade $0.304 million 9. Austin-Dyer 69 kv line upgrade $0.473 million Subtotal: $9.515 million Total: $ million * - Labor and benefits costs normally estimated at 25% of capital costs have not been included. 2.3 Cost estimate for Scenario #5 (sale From EPE to SPS) FACILITY MODIFICATIONS COST * 1a. Additional auto transformer (200 MVA) at Diablo $1.800 million 1b. 345 kv & 115 kv breakers w/structures, switches, Feasibility Study - Page 9 - El Paso Electric Company

10 bus work at Diablo Subtotal: $1.650 million $3.450 million 2. A new Amrad-Caliente 345 kv transmission line $ million Subtotal: $ million 3. Austin North-Chev So 115 kv line upgrade $0.384 million 4. Ascarate-Copper 115 kv line upgrade $0.424 million 5. Ascarate-Chevron 115 kv line upgrade $0.110 million 6. Chevron-Chevron So 115 kv line upgrade $0.242 million 7. Lane-Cooper 115 kv line upgrade $1.122 million Subtotal: $2.282 million Total: $ million - Labor and benefits costs normally estimated at 25% of capital costs have not been included. Note: The above costs do not include costs associated with design and construction of the HVCS terminal, required 345 kv Substation to tap into the existing EPE 345 kv system at Artesia. Feasibility Study - Page 10 - El Paso Electric Company

11 3.0 INTRODUCTION This Feasibility Transmission Interconnection Study has been performed in response to a request made by the XXXXXXXXXXXXXXXXXXXXXXXX (XXX). The objective of this study was to identify potential major impacts associated with the construction and operation of a proposed High Voltage Converter Station (HVCS) located at El Paso Electric Company s (EPE) Artesia HVDC Terminal and to provide XXX with a preliminary view of the efforts, magnitude of potential required modifications, and estimate of the rough costs that would be needed to achieve a successful integration of the HVCS terminal with the EPE system. Based on these preliminary indications of potential project impacts and costs, XXX can then make an informed decision whether to go forward with a more detailed engineering analysis and design effort. Results of the performance simulations have been evaluated against EPE and WSCC planning criteria. In this study, EPE is evaluating the parallel installation of two (2) 100MW High Voltage Converter Station (HVCS) terminals connected parallel to the existing 345 kv Eddy County back-to-back HVDC Terminal. Two power flow base cases, developed by EPE to represent the 2003 Heavy Summer (HS) and 2003 Light Winter (LW) systems, were used in this analysis. The final analyses showed that EPE will require certain system modifications (see cost estimate list in previous Section) to maintain adequate system reliability after HVCS terminals are installed in It should be noted that due to the preliminary character of this analysis, power flow base case representations were not developed with the consensus of all transmission owners, dependent utilities, and users of the New Mexico transmission system. Therefore, study results for the cases may or may not meet all criteria of those utilities. Additionally, Texas-New Mexico Power Company (TNMP), a co-owner in the Artesia HVDC Terminal, the Artesia-Amrad 345 kv line and the Amrad 220 MVA autotransformer, was not consulted during these studies. Therefore, an additional analysis, with TNMP as a participant, will be necessary should XXX decide to proceed with the implementation of this project. Also, at that point the XXX Project may ultimately have to go through the evaluation process of the Western Systems Coordinating Council (WSCC) Procedures for Regional Planning and Project Review and Rating Facilities. It must also be noted that this study is preliminary in nature. It does not use the detailed model of the HVCS terminal and does not model the future (beyond 2003) EPE and/or WSCC system. Additionally, it does not analyze the potential for transient, switching, and harmonic problems as well as potential interactions with the existing HVDC terminal. This study is not meant to analyze every scenario that could occur on the EPE system. The XXX representative insisted upon these limitations. XXX has indicated that at this time it is only interested in learning the magnitude of the potential modifications required to incorporate the proposed HVCS terminal into the EPE transmission system. Feasibility Study - Page 11 - El Paso Electric Company

12 The full analysis would take too much time and incur additional costs in a project that may not materialize should the preliminary analysis show an extensive impact on the EPE transmission system. This study analyzes the primary boundaries around which the EPE system operates under the transmission scenarios agreed to between EPE and XXX. It provides the rough parameters in which the system, with the XXX terminals included, will operate and the required EPE system modifications that will allow operation at those boundaries. It should be noted that the original Study Scope for this study included several scenarios with 80 MW of generation located at the Artesia 345 kv Bus. This generation was anticipated to be located in close proximity to the proposed HVCS terminal. However, since the signing of the Study Scope, the construction of this plant was canceled. Hence, all cases that included the proposed 80 MW generator were omitted from this study report. Feasibility Study - Page 12 - El Paso Electric Company

13 3.1 ASSUMPTIONS The following assumptions are consistent for all study scenarios unless otherwise noted. Project dollar amounts shown are in year 2002 U.S. dollars The cost of the XXX terminal and associated equipment is separate and is not included in this study Transmission costs associated with interconnection of XXX terminal are not included in this study This study assumes that EPE substation space is available for the required system modifications The cost estimates do not include labor costs. Additionally, there was no accounting for spare equipment, but it should be strongly considered. 3.2 CRITERIA The reliability criteria standards used by EPE in the performance of this study are the readily acceptable WSCC and EPE standards and have been included in Appendix 1 (Transmission and Facilities Study: Study Scope) and in Appendix 2 (EPE FERC Form 715). 3.3 PROCEDURE As previously mentioned, the feasibility study analyses conducted by EPE included powerflow and Q-V reactive margin analysis. Detailed discussions for each topic have been included in this report and may be quickly referenced through the Table of Contents. The following procedural considerations were employed: Benchmark and Base Case Development The 2003 Heavy Summer and Light Winter base cases with and without the XXX proposed 200 MW HVCS terminal were developed in order to examine the impact of HVCS terminal on EPE s transmission system. The Benchmark 2003 cases were established by integrating the latest available EPE and New Mexico system representations with the existing WSCC 2003 Heavy Summer and Light Winter cases. Criteria violations in the New Mexico utilities and EPE were flagged for these cases. Consequently, if criteria violations also existed in the With HVCS terminal powerflow cases, no action or modification was taken that would penalize the proposed HVCS terminal. Feasibility Study - Page 13 - El Paso Electric Company

14 EPE powerflow base case one-line diagrams are located in Appendix List of Contingencies Taken in Each Scenario Powerflow analyses was performed for both with and without the HVCS terminal cases. These analyses determined whether any line/transformer loading conditions and/or voltage conditions violated criteria. First the system was modeled based on the scenario under consideration and all lines in service. Contingencies were then taken. The same contingencies were taken on all scenarios and are identified in Appendix 4. Known worst case contingencies were selected using engineering judgement to determine the most likely outages to stress the EPE system QV Reactive Margin Analysis As outlineed in the Study Scope, EPE performed Q-V reactive margin analyses for the 2003 Heavy Summer and Light Winter cases. QV analyses were conducted in order to verify that the WSCC Voltage Stability Criteria is met and EPE reactive power margin is within an acceptable limits under the worst system contingencies. This Q-V analysis was based on WSCC methodology, which called for an increase of EPE area load by 5% above the base case, and verifying whether the positive reactive margin still existed under the worst contingency scenario. Prior experience has shown that the worst single contingencies impacting reactive margin are the Springerville-Luna 345 kv line, the Luna-Diablo 345 kv line, and the Greenlee-Hidalgo 345 kv line. The buses most impacted are the 345 kv buses at Luna, Diablo, Arroyo, Caliente, and Newman. Future facility studies will address VAR margins in the Amrad substation area during an Amrad-Caliente 345 kv line contingency. This contingency appeared to be non-convergent due to the weakness of this part of the transmission system after installation of the proposed HVCS terminal. An improved model of the HVCS terminal should be available at a later date which will allow for more accurate modeling. At the present time, this study has found that the worst system contingency with the proposed HVCS terminal in operation is the Luna-Diablo 345 kv line contingency. Hence, this contingency was used in the analysis to evaluate reactive margins for all the scenarios in consideration. Q-V plots were created for all critical buses, and identify the reactive margins available at these key 345 kv buses. Feasibility Study - Page 14 - El Paso Electric Company

15 3.4 MODELING HVCS TERMINAL As per the XXX request, the proposed 200 MW HVCS was modeled as a generator for cases of sale from SPS to WSCC and, as a load on the SPS side with an SVG for cases of sale from WSCC/EPE to SPS. It should be noted that a better model of the HVCS terminal should be available with the release of GE PSLF program, version 13 in February All scenarios that included the HVCS terminal modeled the terminal as connected at a new 345 kv bus. This new bus was modeled as connected to the existing Artesia 345 kv bus through a bus tie. Feasibility Study - Page 15 - El Paso Electric Company

16 4.0 POWERFLOW and QV ANALYSES In determining the modifications required for an interconnection of the proposed 200 MW HVCS terminal, a number of scenarios representing several scheduling possibilities were investigated. These scenarios were not meant to analyze every scenario that could occur with incorporation of the HVCS terminal into the EPE system since that approach would take too much time. This study was divided into two Tasks, with Task One evaluating scenarios before the installation of the proposed HVCS terminal and Task Two evaluating the same scenarios as Task One except the 200 MW HVCS terminal was modeled. The description of all case scenarios for Task One and Task Two cases is presented below: Task One: The Task One study cases represented the study year 2003 Heavy Summer and Light Winter system, for pre-project scenarios. None of the scenarios considered in Task One have the HVCS modeled. All scenarios in Task One will be marked as Benchmark scenarios and will be used for comparison with Task Two scenarios that model the proposed HVCS terminal. Scenario 1 (Benchmark): Scenario 2 (Benchmark): Scenario 3 (Benchmark): Scenario 4 (Benchmark): Scenario 5 (Benchmark): 2003 Heavy Summer Base case with no HVCS terminal. Eddy County terminal operating in Western (from SPS to EPE) direction at a maximum of 220 MW Light Winter Base case with no HVCS terminal. Eddy County terminal operating in Western (from SPS to EPE) direction at a maximum of 220 MW Heavy Summer Base case with no HVCS terminal. Eddy County terminal operating in Eastern (from EPE to SPS). The amount of transfer in this direction will be determined based on the maximum power transfer that wouldn t require any EPE system modifications Light Winter Base case with no HVCS terminal. Eddy County terminal operating in Eastern (from EPE to SPS) direction at a maximum of 220 MW. The amount of transfer in this direction will be determined based on the maximum power transfer that wouldn t require any EPE system modifications Light Winter Base case with no HVCS terminal. Eddy County terminal operating in Eastern (from EPE to Feasibility Study - Page 16 - El Paso Electric Company

17 SPS). The amount of transfer in this direction will be determined based on the maximum power transfer that wouldn t require any EPE system modifications. This Scenario is identical to scenario 4. Task Two: As discussed earlier the scenarios in Task Two are the same as scenarios in Task One except the proposed HVCS terminal was modeled for all scenarios. These scenarios will be marked as a Comparison scenarios. Scenario 1 (Comparison): Scenario 2 (Comparison): Scenario 3 (Comparison): Scenario 4 (Comparison): Scenario 5 (Comparison): 2003 Heavy Summer Base case with HVCS terminal. Eddy County terminal operating in Western (from SPS to EPE) direction at a maximum of 220 MW. The proposed HVCS terminal will add 200 MW to these transfers Light Winter Base case with HVCS terminal. Eddy County terminal operating in Western (from SPS to EPE) direction at a maximum of 220 MW. The proposed HVCS terminal will add 200 MW to these transfers Heavy Summer Base case with HVCS terminal. Eddy County terminal operating in Eastern (from EPE to SPS) direction. This scenario depicts sale to SPS from WSCC. The proposed HVCS terminal will add 200 MW to these transfers Light Winter Base case with HVCS terminal. Eddy County terminal operating in Eastern (from EPE to SPS) direction at a maximum of 220 MW. This scenario depicts sale to SPS from WSCC. The proposed HVCS terminal will add 200 MW to these transfers Light Winter Base case with HVCS terminal. Eddy County terminal operating in Eastern (from EPE to SPS) direction at a maximum of 220 MW. This scenario depicts sale to SPS from EPE. The proposed HVCS terminal will add 200 MW to these transfers. Powerflow analyses were performed for Scenarios 1 through 5 in both Tasks. A base case was first developed for each scenario, showing the system with all lines in service. Voltage and/or loading criteria violations in the All Lines in Service (ALIS) cases were noted for the EPE system as well as for other New Mexico utilities. These violations are shown in the Base Case Tables listed in Appendix 5. Feasibility Study - Page 17 - El Paso Electric Company

18 Contingency powerflow analyses were also performed for all of the scenarios in both Tasks. A list of the contingencies analyzed is shown in Appendix 4. For these contingencies, only criteria violations that affect EPE elements are discussed in detail. Bus voltage deviations between the base case and all contingency conditions were investigated and discussed both with and without HVCS terminal. Please note that although impacts to other utilities were recorded in the result tables, in Appendix 5, they were not considered for upgrades in this analysis. Arrangements with other New Mexico utilities should be made to verify that the proposed HVCD terminal has no adverse effect on their systems. Also, please note that in the power flow overload tables in this report, the MVA Flow and the Overload in %, may not exactly correspond in all cases. The reason for this is that percentage overload is always determined based on the flow at the elements from bus, whereas the MVA Flow is based on the elements first bus. Also, the actual bus voltage impacts these calculations because a transmission line rating is based on current flow not MVA flow and may vary a few percentage points with the variations in the transmission system voltages. Feasibility Study - Page 18 - El Paso Electric Company

19 4.1 Results In this study, a relative approach was used to determine the impact of the proposed 200 MW HVCS terminal on the performance of the power system. First, performance of the existing system was determined in order to establish the baseline (results of Task one analysis). Then system performance with the new 200 MW HVCS terminal was determined (results of Task two analyses) and compared to the baseline. This relative approach removes any ambiguities as to the actual impact of the proposed HVCS terminal since existing criteria violations were identified. The power flow analysis evaluated the impact of the proposed HVCS terminal with respect to existing system performance and specific system loading and bus voltage criteria. Criteria violations that occurred in the post-project system, but did not occur in the existing system, are considered attributable to the proposed HVCS terminal. The scenarios listed above in this study were used to determine whether modifications were required on the EPE system to allow the proposed HVCS terminal operation. These scenarios represent various ways in which the HVCS terminal output may be scheduled to both EPE and other WSCC entities. Also, these scenarios attempted to represent the maximum stress that can be placed on the EPE system with the proposed HVCS terminal Scenario # Benchmark analysis Power Flow analysis: The EPE system was represented in this Benchmark case with heavy summer EPE and New Mexico loads but without HVCS terminal. No transmission system problems were found during power flow analysis for this Benchmark case. No transmission lines or transformers were loaded above their normal ratings for the base case or emergency ratings during contingencies. All voltages were within acceptable limits. Several transmission elements exceeded their normal rating but not their emergency ratings for five different contingencies (see table below). Feasibility Study - Page 19 - El Paso Electric Company

20 EPE system overloads above normal rating. Scenario #1 (Benchmark) no HVCS (2003HS) From To Loading MVA Amps Rate Used Contingency ARROYO 115 ARROYO LUNA 345/115 ARROYO 115 ARROYO CAL-NEWMAN 345 ARROYO 115 ARROYO AMRAD 115/345 AUSTIN_N 115 CHEVSO SUNSET-RIO G 115 CALIENTE 115 CALIENTE CAL 115/345 LAS_CRUC 115 ARROYO LUNA 345/ QV analysis: The QV analysis examined the reactive margins for the pre-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna- Diablo 345kV line in the EPE control area. This analysis shows sufficient reactive margins. These VAR margins provided in the table below Reactive Margins. Scenario #1 (Benchmark) no HVCS (2003HS) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Comparison analysis Power Flow analysis: The HVCS terminal was modeled in this scenario and 200 MW were scheduled for delivery to WSCC through EPE transmission system. The addition of HVCS caused significant changes in EPE system flows and resulted in the loadings above emergency rating during contingencies of Luna and Caliente 345/115 kv autotransformers. Arroyo and second Caliente 345/115 kv autotransformers were loaded above their respected emergency ratings. EPE system overloads for this scenario can be found in the table below. The overloads above emergency rating are shown in bold italic. Feasibility Study - Page 20 - El Paso Electric Company

21 EPE system overloads above normal and emergency rating. Scenario #1 (Comparison) with HVCS (2003HS) From To Loading MVA Amps Rate Contingency ANTHONY 115 NEWMAN ARR 115/345 ARR PS 345 ARROYO AMRAD-ARTESIA345 ARROYO 115 ARROYO LUNA 345/115 ARROYO 115 ARROYO AMRAD 115/345 ARROYO 115 ARROYO LUNA-DIABLO CALIENTE 115 CALIENTE CAL 115/345 LAS_CRUC 115 ARROYO LUNA 345/115 LUNA 345 LUNA LUNA-HID 345 Additionally, the contingency of Amrad-Caliente 345 kv transmission line resulted in non-convergence caused by a significant overloading of Amrad-Newman 115 kv system. An attempt to solve this contingency for line flows by switching various reactive devices in the post contingency didn t succeed. The DC flow solution showed significant solution mismatches. The DC flow map, however, can be useful to visualize an approximate power flow distribution after Amrad-Caliente 345 kv line contingency. No voltage criteria violations were found in this scenario QV analysis: The QV analysis examined the reactive margins for the post-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna- Diablo 345kV line in the EPE control area. This analysis shows sufficient reactive margins. These VAR margins provided in the table below. Please note that the QV analyses for Amrad-Caliente 345 kv transmission line could not be performed because the case was divergent due to the voltage collapse in the Amrad substation area. The future facilities study will address this problem. Reactive Margins. Scenario #1 (Comparison) with HVCS (2003HS) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Final Analysis for Scenario #1 Feasibility Study - Page 21 - El Paso Electric Company

22 Scenario #1 show significant power flow impacts from the installation of the proposed HVCS terminal. Several transmission elements were loaded above their emergency ratings. Because of a non-convergence of the Amrad-Caliente 345 kv transmission line contingency the direct assessment of the impact of the proposed HVCS during this contingency is not possible from the results of the power flow analysis. However it is clear from the system topology that the installation of the proposed HVCS caused significant overloads in the Amrad-Newman 115 kv transmission area. For example, for the outage of the Caliente-Amrad 345 kv line, the power delivered to Artesia by the proposed HVCS and the existing HVDC terminal must flow through the Amrad 345/115 kv transformer. In the benchmark system, the maximum of 220 MW delivered by the HVDC terminal will not overload the Amrad 345/115 kv transformer, which has an emergency rating of 261 MVA. In the Comparison scenario, however, with the proposed HVCS at 200 MW, the outage of the Caliente-Amrad 345 kv line will cause the Amrad 345/115 kv transformer to carry the power transferred by the new HVCS terminal, in addition to the power delivered by the HVDC terminal. With the new HVCS terminal in service, therefore, a total of 420 MW must be carried through the Amrad transformer, which is clearly in violation of the transformer's emergency rating. Similarly, the whole Amrad-Newman 115 kv link, as well as the Alamogordo Tap-Alamogordo 115 kv line, will be overloaded with the new HVCS terminal in service. The following System additions are recommended in order to mitigate transmission overloads caused by the installation of the proposed HVCS terminal: Additional 345/115 kv autotransformer at Arroyo 345 kv Substation Additional 345/115 kv autotransformer at Caliente 345 kv Substation Second Amrad-Caliente 345 kv transmission line Additionally, the condition of Amrad-Artesia 345 kv transmission line and its ability to transmit 420 MW need to be investigated. Please note that due to the non-convergence of Amrad-Caliente 345 kv transmission line the voltage situation in the Amrad transmission area during this contingency remains uncertain. Additional system improvements may be required in order to mitigate any potential undervoltage problems. These issues will be addressed during future a facilities studies Scenario # Benchmark analysis Feasibility Study - Page 22 - El Paso Electric Company

23 Power Flow analysis: The EPE system was represented in this Benchmark case with Light Winter EPE and New Mexico loads but without HVCS terminal. No transmission system problems were found during power flow analysis for the Benchmark case. No transmission lines or transformers were loaded above their normal ratings for the base case or emergency ratings during contingencies. All voltages were within acceptable limits. Additionally, no voltage problems were found for this Benchmark scenario QV analysis: The QV analysis examined the reactive margins for the pre-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna- Diablo 345 kv line in the EPE control area. This analysis shows sufficient reactive margins. These VAR margins provided in the table below Reactive Margins. Scenario #2 (Benchmark) no HVCS (2003LW) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Comparison analysis Power Flow analysis: The HVCS terminal was modeled in this scenario and 200 MW was scheduled for delivery to WSCC through EPE transmission system. The addition of HVCS did not cause loadings above emergency rating during any of the contingencies with exception of Amrad-Caliente 345 kv transmission line contingency that didn t solve. The Arroyo Phase Shifter was loaded slightly above its normal rating during the contingency of Amrad-Artesia 345 kv transmission line. As stated above, the contingency of Amrad-Caliente 345 kv transmission line resulted in a non-convergence powerflow case. This non-convergence was caused by a significant overloading of Amrad-Newman 115 kv system. Feasibility Study - Page 23 - El Paso Electric Company

24 No voltage criteria violations were found in this scenario QV analysis: The QV analysis examined the reactive margins for the post-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna- Diablo 345 kv line in the EPE control area. This analysis shows sufficient reactive margins. These VAR margins provided in the table below. Please note that the QV analyses for Amrad-Caliente 345 kv transmission line can t be performed because the case is divergent due to the voltage collapse in the Amrad substation area. The future facilities study will address this problem. Reactive Margins. Scenario #2 (Comparison) with HVCS (2003LW) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Final Analysis for Scenario #2 Scenario #2 show significant power flow impacts from the installation of the proposed 200 MW HVCS terminal. These impacts show in the Amrad-Newman 115 kv system during contingency of Amrad-Caliente 345 kv transmission line. Because of a non-convergence of the Amrad-Caliente 345 kv transmission line contingency the direct assessment of the impact of the proposed 200 MW HVCS during this contingency is not possible from the results of the power flow analysis. However, as it was discussed earlier in this study (Scenario #1; Final Analysis) the proposed HVCS terminal caused overloads in the Amrad-Newman transmission area and will require following mitigation measures: Second Amrad-Caliente 345 kv transmission line As discussed in Scenario #1, the condition of Amrad-Artesia 345 kv transmission line and its ability to transmit 420 MW need to be investigated. Please note that due to the non-convergence of Amrad-Caliente 345 kv transmission line the voltage situation in the Amrad transmission area during this contingency remain uncertain. Additional system improvements may be required in order to mitigate any Feasibility Study - Page 24 - El Paso Electric Company

25 potential undervoltage problems. These issues will be addressed during future a facilities studies Scenario # Benchmark analysis Power Flow analysis: The EPE system was represented in this Benchmark case with heavy summer EPE and New Mexico loads. The HVCS terminal was not included. In this Scenario, EPE was modeled to sell power to SPS. As agreed in the Study Scope, the amount of this sale was determined at a level where no major transmission upgrades of the EPE transmission system were necessary. The analysis for this scenario found that during 2003 Heavy Summer system condition, no more than 30 MW can be sold to SPS without major transmission system upgrades. Therefore, this scenario models 30 MW of sale from EPE to SPS and as a result the existing HVDC converter is modeled transmitting 30 MW in the eastern (to SPS) direction. EPE system overloads above normal rating. Scenario #3 (Benchmark) no HVCS (2003HS) From To Loading MVA Amps Rate Used Contingency AMRAD 115 ALAMOTAP ARR 115/345 ARROYO 115 ARROYO CAL-NEWMAN 345 ASCARATE 115 COPPER CAL-NEWMAN 345 AUSTIN_N 115 CHEVSO CAL-NEWMAN 345 CHEVRON 115 ASCARATE CAL-NEWMAN 345 CHEVSO 115 CHEVRON CAL-NEWMAN 345 COPPER 115 LANE # CAL-NEWMAN 345 DYER 69 AUSTIN CAL-NEWMAN 345 MESA # 115 RIO_GRAN CAL-NEWMAN 345 NEWMAN 115 VISTA # CAL-NEWMAN 345 SUNSET_N 115 RIO_GRAN CAL-NEWMAN 345 ARROYO 115 ARROYO LUNA 345/115 SUNSET_N 115 RIO_GRAN MESA-RIO G 115 ARR PS 345 ARROYO NEWMAN-AFTON 345 DIABLO 115 DIABLO NEWMAN-AFTON 345 LUNA 345 LUNA NEWMAN-AFTON 345 MESA # 115 RIO_GRAN NEWMAN-AFTON 345 SUNSET_N 115 RIO_GRAN NEWMAN-AFTON 345 AUSTIN_N 115 CHEVSO SUNSET-RIO G 115 MESA # 115 RIO_GRAN SUNSET-RIO G 115 Feasibility Study - Page 25 - El Paso Electric Company

26 No transmission system problems were found during power flow analysis for this Benchmark case. No transmission lines or transformers were loaded above their normal ratings for the base case or emergency ratings during contingencies. Several transmission elements exceeded their normal rating but not their emergency ratings for six different contingencies (see table above). All voltages were found to be within acceptable limits QV analysis: The QV analysis examined the reactive margins for one pre-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna- Diablo 345 kv line in the EPE control area. This analysis shows sufficient reactive margins. These VAR margins provided in the table below Reactive Margins. Scenario #3 (Benchmark) no HVCS (2003HS) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Comparison analysis Power Flow analysis: The HVCS terminal was modeled in this scenario and 200 MW were scheduled for delivery to SPS. The source of this 200 MW was chosen outside the EPE transmission system area. The addition of HVCS caused significant changes in EPE system flows and resulted in the loadings above emergency rating during contingencies of four transmission lines and autotransformers. Several EPE transmission lines and autotransformers were loaded above their respected emergency ratings. EPE system overloads for this scenario can be found in the table below. The overloads above emergency rating are shown in bold italic. The contingency of Amrad-Caliente 345 kv transmission line resulted in nonconvergence caused by a significant overloading of Amrad-Newman 115 kv system. Feasibility Study - Page 26 - El Paso Electric Company

27 No voltage criteria violations were found in this scenario for any of the converged cases. EPE system overloads above normal and emergency rating. Scenario #3 (Comparison) with HVCS (2003HS) From To Loading MVA Amps Rate Used Contingency ARR PS 345 ARROYO NEWMAN-AFTON 345 ARR PS 345 ARROYO LUNA-AFTON 345 ARROYO 115 ARROYO CAL-NEWMAN 345 ASCARATE 115 COPPER CAL-NEWMAN 345 AUSTIN_N 115 CHEVSO CAL-NEWMAN 345 AUSTIN_N 115 CHEVSO SUNSET-RIO G 115 AUSTIN_N 115 CHEVSO SUNSET-ASC 115 CHAPARAL 115 ORO_GRAN CAL-NEWMAN 345 CHEVRON 115 ASCARATE CAL-NEWMAN 345 CHEVSO 115 CHEVRON CAL-NEWMAN 345 CHEVSO 115 CHEVRON SUNSET-RIO G 115 COPPER 115 LANE # CAL-NEWMAN 345 COPPER 115 LANE # NEWMAN-AFTON 345 DIABLO 115 DIABLO NEWMAN-AFTON 345 DIABLO 115 DIABLO DIA 115/345 DIABLO 115 DIABLO LUNA-AFTON 345 DYER 69 AUSTIN CAL-NEWMAN 345 LUNA 345 LUNA NEWMAN-AFTON 345 LUNA 345 LUNA LUNA-AFTON 345 MESA # 115 RIO_GRAN NEWMAN-AFTON 345 MESA # 115 RIO_GRAN CAL-NEWMAN 345 MESA # 115 RIO_GRAN LUNA-AFTON 345 MESA # 115 AUSTIN_N NEWMAN-AFTON 345 MESA # 115 RIO_GRAN SUNSET-RIO G 115 MESA # 115 AUSTIN_N CAL-NEWMAN 345 MESA # 115 RIO_GRAN SUNSET-ASC 115 MESA # 115 AUSTIN_N LUNA-AFTON 345 NEWMAN 115 VISTA # CAL-NEWMAN 345 NEWMAN 115 CHAPARAL CAL-NEWMAN 345 SANTA_FE 69 DALLAS CAL-NEWMAN 345 SANTA_FE 69 SUNSET CAL-NEWMAN 345 SANTA_FE 69 SUNSET NEWMAN-AFTON 345 SANTA_FE 69 DALLAS NEWMAN-AFTON 345 SUNSET_N 115 RIO_GRAN CAL-NEWMAN 345 SUNSET_N 115 RIO_GRAN NEWMAN-AFTON 345 SUNSET_N 115 RIO_GRAN MESA-RIO G 115 SUNSET_N 115 RIO_GRAN LUNA-AFTON 345 SUNSET_N 115 ASCARATE CAL-NEWMAN 345 SUNSET_N 115 ASCARATE NEWMAN-AFTON 345 Feasibility Study - Page 27 - El Paso Electric Company

28 QV analysis: This QV analysis examined the available reactive margins for one post-project scenario. Reactive margin curves were developed for five buses in the EPE area, for the outage of Luna-Diablo 345 kv line in the EPE control area. The following table shows adequate reactive margins for all critical buses in EPE transmission area. Please note that the QV analyses for Amrad-Caliente 345 kv transmission line could not be performed because the case is divergent due to the voltage collapse in the Amrad substation area. The future facilities study will address this problem. Reactive Margins. Scenario #3 (Comparison) with HVCS (2003HS) QV Bus VAR Margin Contingency Arroyo Luna - Diablo 345 KV line Luna Luna - Diablo 345 KV line Diablo Luna - Diablo 345 KV line Newman Luna - Diablo 345 KV line Caliente Luna - Diablo 345 KV line Final Analysis for Scenario #3 Scenario #3 show significant power flow impacts from the installation of the proposed 200 MW HVCS terminal. Several transmission elements were loaded above their emergency ratings. Because of the non-convergence powerflow solution for the Amrad-Caliente 345 kv transmission line contingency, the direct assessment of the impact of the proposed HVCS during this contingency is not possible from the results of the power flow analysis. As it was previously discussed (see Scenario #1, Final Analysis) it is clear from the system topology that the installation of the proposed 200 MW HVCS caused significant overloads in the Amrad-Newman 115 kv transmission path. The following System additions and modifications are recommended in order to mitigate transmission overloads caused by the installation of the proposed HVCS terminal: Additional 345/115 kv autotransformer at Arroyo 345 kv Substation Additional 345/115 kv autotransformer at Diablo 345 kv Substation Additional 345/115 kv autotransformer at Luna 345 kv Substation Second Amrad-Caliente 345 kv transmission line Upgrade of Mesa-Rio Grande 115 kv transmission line Feasibility Study - Page 28 - El Paso Electric Company