El PASO ELECTRIC COMPANY 2014 BULK ELECTRIC SYSTEM TRANSMISSION ASSESSMENT FOR YEARS

El Paso Electric Company El PASO ELECTRIC COMPANY 2014 BULK ELECTRIC SYSTEM TRANSMISSION ASSESSMENT FOR YEARS 2015 2024 A Review on System Performance Following Extreme Bulk Electric System Events of the El Paso Electric (EPE) Company Transmission System to Demonstrate Compliance as Required By TPL-004 EPE System Planning 10/07/2014 1

El PASO ELECTRIC COMPANY 2014 BULK ELECTRIC SYSTEM TRANSMISSION ASSESSMENT FOR YEARS 2015-2024 A Review on System Performance Following Extreme Bulk Electric System Events of the El Paso Electric (EPE) Company Transmission System to Demonstrate Compliance As Required By TPL-004 Introduction This memo explains the methodology and the study results for compliance with the North American Electric Reliability Corporation (NERC) Standard TPL-004-0a - system performance following extreme bulk electric system events on El Paso Electric s (EPE) high voltage transmission system (System). EPE has determined the two most extreme events under TPL-004-0a Category D Table I (see table on next page for Category D definitions) that could jeopardize the normal operation of its System would be Event 8 (E8) and Event 10 (E10). This study evaluated E8, the loss of a substation (one voltage level plus transformers) with at least three transmission lines, or with two transmission lines and an autotransformer (N 3). Certain substations also included loss of generation due to electrical connections of those generators on the voltage level dropped (most critical event). The second extreme event, E10, evaluated the loss of all generating units at a station. EPE has judged these two events to be the most extreme under Category D. On the EPE System, any single fault having normal clearing is not an issue. The area of concern lies with the loss of multiple lines. That is, no single fault will endanger the loss of an entire substation or all generating units in EPE s System. The concern would be the loss of any line after fault clearing that could potentially trigger additional transmission line outages thus creating a cascading effect. This study however, did not model a cascading event but instead modeled the loss of three or more major elements at one voltage level or losing all generating units at a station simultaneously. These two events should capture a snapshot of the System under such conditions. The purpose of this assessment was to determine and identify potential thermal overloads and extreme low-voltage conditions due to severe system impacts such as the events mentioned above. This assessment does not include the development of new measures that could mitigate the impacts of the events. As stated in this Standard, system simulations and associated assessments are needed periodically to ensure that reliable systems are developed that meet specified performance requirements, with sufficient lead time and to continue to be modified or upgraded as necessary to meet present and future System needs. For such extreme N 3 events, EPE s under-voltage scheme monitors system conditions and sheds native load accordingly by using low-voltage relays. In modeling the events, EPE allowed existing system adjustments such as utilizing area capacitor banks (reactive resources), increasing local generation, and/or shedding native load to help improve voltage profiles and allow cases to converge. Table I below illustrates the extreme events under Reliability Standard TPL-004-0a Category D. EPE has judged Events #8 & #10 as most extreme and critical to its System. 2

Table I. Transmission System Standards Normal and Emergency Conditions Requirements As stated in NERC Reliability Standard TPL-004-0a_R1, the Planning Authority and Transmission Planner (EPE is both) shall each demonstrate through a valid assessment that its portion of the interconnected transmission system is evaluated for the risks and consequences of a number of each of the extreme contingencies that are listed in Category D of Table I. This may involve substantial loss of customer demand and generation in a widespread area. Portions or all of the interconnected systems may or may not achieve a new stable operating point. The risks and consequences of these contingencies should be reviewed by the entities responsible for the reliability of the interconnected transmission lines. Actions to mitigate or eliminate the risks and consequences are at the discretion of those entities. In modeling these events, EPE did strive to achieve new stable operating points in non-convergence cases by shedding native (EPE) and southern New Mexico (PNM and Tri-State) load to achieve convergence and new steady-state conditions. It did not however, analyze for transient or angular instability. This study was performed using powerflow analyses. EPE s System Planning has determined that the most severe contingencies impacting the EPE transmission system are not transient limited but rather limited by steady-state and reactive issues. For that reason, E8 and E10 were judged the most extreme events that would produce more severe system results or impacts. Substations with only two transmission lines or radial lines were not considered a severe threat. The study looked at two near-term EPE Transmission 3

System Plan (Plan) case, years 2015 and 2019, to perform these Category D events thus fulfilling and meeting requirements of this Reliability Standard. This study did not look at ways to mitigate or eliminate the overloaded facilities resulting from substation contingencies, but only to identify above emergency thermal overloads or extreme low-voltage conditions as stated earlier. Neither did this study consider the effects of EPE s under-voltage load shedding (UVLS) program that is meant to arrest voltage decay during system contingencies by shedding load. It also did not trip overloaded transmission lines to determine if other transmission lines overload under this condition. Engineering judgment indicates that if enough lines were to trip, the load served by those lines and load shed by undervoltage relays would be sufficient and thus avoid cascading outages within the electrical system. In performing this study, EPE, the Planning Authority (PA) and the Transmission Planner (TP), followed and made certain that requirements in Reliability Standard TPL-004-0a_R1 (R1.1 though R1.4) were in compliance. The results of this reliability assessment through system simulations were documented and included in this memo as described in Reliability Standard TPL-004-0a_R2 and upon request, will furnish supporting results and Plan Cases used in this evaluation. Measures EPE, serving as PA and as TP, through an assessment of its transmission system in the near-term years of 2015 and 2019, has performed a valid assessment of system responses under the conditions stated above as specified in Reliability Standard TPL-004-0a R1 and R2. The Standard (R1.2) requires near-term evaluation in years one through five. EPE asserts that by evaluating year one and year five in the near-term, most of its present and future expansion projects will be included in the assessment of its transmission system, thus portraying a realistic model of the present and near future system. This memo and the results herein, serve as evidence and documentation to the Western Electricity Coordinating Council (WECC), EPE s Compliance Monitor, of its reliability assessments per Reliability Standards TPL-004-0a_R1. Methodology for Category D, Event #8 Loss of a Substation Voltage Level Two heavy-summer cases, the 2015 and the 2019 Plan cases, were used to determine the impacts on the EPE transmission system under the substation outages (one voltage level plus transformers) as shown in the results section below. Criteria used to identify system violations included overloads at 130% or above of the emergency ampere ratings for transmission lines and emergency MVA rating for transformers. The logic behind using the 130% emergency rating is related to the average over-current relay settings at EPE. Cases that did not converge (due to extreme system conditions) were given an opportunity to converge by shedding some southern New Mexico and/or EPE native load, increasing local generation, and/or adding dynamic or static reactive support. This study did not focus on finding minimum load levels for compliance. The requirement does not specify the modeling of various generation dispatch scenarios; however, this study went beyond the scope of the requirement and modeled the effects of partial and/or full generation output from Rio Grande Power Plant and with Copper Power Plant either in or out of service during the loss of some local generation events. 4

Voltage performance under the N 3 scenario was also monitored, although Category D of the NERC/WECC Planning Standards does not list a minimum limit on voltage magnitudes for extreme contingencies. Nonetheless, voltage magnitudes falling below 90% (0.9 PU - per unit) of nominal were identified and reported. Before doing so however, an attempt to improve the lowvoltage magnitudes was done by adjusting shunt capacitors and re-running the powerflow. Substation bus voltages remaining at or below 0.90 PU are reported in the results section below. The study modeled the system in a post-fault state, i.e., after a fault is removed by opening breakers on the faulted facilities and dropping the required transmission facilities. It monitored the impact of losing an entire voltage level at substations within the EPE System served by three or more transmission facilities (N 3). For example, if a substation had N 3 transmission lines at one voltage level and two or less transmission lines at the other level, then only the voltage level with N 3 lines was dropped. If the substation had N 3 transmission lines at both voltage levels, then each level was dropped separately in a dedicated load flow and the results of each were documented. In addition, if the substation had generating units at the bus voltage level being evaluated, the bus and the units were dropped simultaneously (N 3 lines). For clarification, dropping a substation bus voltage level includes disabling high-voltage facilities attached to the substation bus. These facilities include transmission lines, autotransformers, capacitors, reactors, and/or generating units. Methodology on Category D, Event #10 Loss of All Generating Units in a Station The loss of all generating units at local and nearby power stations was also evaluated in this study. Powerflow cases were solved by importing more power (through Path 47) to balance any area generation deficiency (i.e. to correct for load-resource imbalance). In the 2015 Plan case, all Newman (NWM), Rio Grande (RG), and Luna (LEF) generating units were dropped in separate scenarios and the results documented. Similarly, in the 2019 Plan case, all Newman, Rio Grande, Montana (MPS), and Luna generating units were dropped for system evaluation. Although EPE does not own any part of Luna generation, its contribution to southern New Mexico and EPE s System make it important for maintaining normal operating conditions in the area. The methods for monitoring extreme conditions were similar to that done for Category D Event #8 as explained above. Results From Category D, Event #8-2015 Plan Case The results from Event #8 of the 2015 Plan case are shown show in Table II below. Four out of thirty-seven substation outages evaluated resulted in at least one transmission facility overloading above 130% of emergency rating and/or transmission voltage bus at 0.90 PU or below in EPE or PNM s area. One substation outage caused an overload on EPE s transmission system. The Arroyo 345 kv (No. 4 of Table II) bus outage (including both Arroyo 345/115 kv autotransformers) resulted in the Anthony-Newman 115 kv line overloading to 157.7% of its emergency rating. One substation outage caused PSLF Area 10 (New Mexico) transmission lines to experience extreme overloads and low voltages. The Luna 345 kv outage (No. 19) isolated all LEF 5

generating units and caused three of Tri-State Generation & Transmission Association s (TSGT) 115 kv transmission lines to have emergency overloads of over 130%. This outage also caused five New Mexico (Area 10) buses to have voltages below 0.90 per unit. These results included a load shed of 100 MW in Area 10 (in Zones 104, 123, 130, 131, and 132) and 200 MW in EPE s area (Zone 110). EPE generation was at maximum output and EPE imports were reduced to 425 MW to help the powerflow case converge. Under-voltage load shed schemes or other remedial action schemes will shed additional load lessening thermal overloads and voltage drop. Of the 37 substation outages evaluated, four cases (consisting of a total of six scenarios) did not converge without significant adjustments. The Luna 345 kv outage was the most difficult system to converge and required shedding load as detailed above. The Amrad 115 kv outage (No. 2) required a fictitious Static Var Generator (SVG) at the Alamogordo 115 kv bus with a capacitive output of 52 MVAR to converge. Note that the load and thus the under-voltage load shedding in the Alamogordo area is served and operated by PNM and Tri-State and was not modelled in this study. The other two cases were Newman 115 kv bus + all generation (No. 23 & 24) and Rio Grande 115 kv bus + generation (No. 28 & 29). Both of these cases included two scenarios all of which required increasing local EPE generation and EPE imports as detailed in Table II. After getting all cases to converge, five EPEs buses had voltage under 0.90 per unit. The low voltage buses appear in the two Newman 115 kv bus + generation scenarios (No. 23 & 24). Results From Category D, Event #10-2015 Plan Case None of the three loss of all generation at a station powerflow outages failed to converge at forecasted load. No overloads at or above 130% of emergency or low voltage conditions were identified. The results are shown show in Table III below. Results From Category D, Event #8-2019 Plan Case The results from Event #8 of the 2019 Plan case are shown show in Table IV below. Three out of thirty-eight substation outages evaluated resulted in transmission facilities loading above their 130% of emergency rating and/or transmission voltages at or below 0.90 PU. The Arroyo 345 kv (No. 4 of Table IV) bus outage (including both Arroyo 345/115 kv autotransformers) resulted in the Anthony-Newman 115 kv line overloading to 132.2% of its emergency rating. The Luna 345 kv outage (No. 19) isolated all LEF generating units and the powerflow would not converge unless 300 MW of load was shed and all of EPE s generation (except Copper) was turned on. This outage caused three TSGT (Area 10) 115 kv transmission lines to have emergency overloads of over 130%. In 2019, EPE will have all four Montana Power Station (MPS) Units (352 MW summer and 420 MW winter capacities) in service. The addition of the MPS generation helps eliminate the overloads and low voltage issues found for this same outage in the 2015 scenario. The 2019 Plan case resulted in no overload or low voltage issues when EPE generation was increased and because of the additional generation, El Paso Imports (EPI) was reduced to 412 MW. The two other scenarios that showed low voltage issues were the Newman 115 kv bus outages (No. 24 & 25 in Table IV). These two scenarios required increasing local EPE generation as 6

detailed in Table IV. After getting all cases to converge, there were a total of 8 EPE buses with voltages under 0.90 per unit as detailed in Table IV. The 2019 Plan case included a Montana Power Station (MPS) 115 kv generation outage which required maximum outputs in Rio Grande, Copper, and Newman generation. The Luna 345 kv outage was the most difficult case to converge and required shedding load as detailed above. However, with the addition of the final 2 MPS units, no low voltage or thermal overload issues were observed for this outage. The Amrad 115 kv outage (No. 2) required a fictitious SVG at the Alamogordo 115 kv bus (see note in Category D, Event #8, 2015) with a capacitive output of 35 MVAR to converge. Results From Category D, Event #10-2019 Plan Case None of the four loss of all generation at a station powerflow outage scenarios failed to converge at the forecasted load, nor were any overloads at or above 130% of emergency, nor were any low voltage conditions identified. The results are shown show in Table V below. This concludes the NERC Reliability Standard TPL-004-0a, Category D evaluation for El Paso Electric Company. The study follows all requirements of the Standard Detail documentation and plan cases used to perform this study may be obtained from System Planning. 7

No. SUBSTATION OUTAGE (kv) TABLE II: 2015 PLAN CASE NERC TPL-004, CATEGORY D # 8 LOSS OF A SUBSTATION (One Voltage Level plus Transformers) - 3 OR MORE FACILITIES OVERLOADED FACILITY (kv) 130% (1) RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU LOAD SHED (4) 1 AFTON 345 Afton Generation was OFF 2 AMRAD 115 Case required 52 MVAR from a fictitious SVG at ALAMOGCP 115 kv bus to converge. 3 ANTHONY 115 4 ARROYO 345 + Autos Anthony-Newman 115 157.7 Includes dropping both 345/115 kv autotransformers. 5 ARROYO 115 + Autos 6 ASCARATE 115 + Autos Includes dropping both 115/69 kv autotransformers. 7 ASCARATE 69 + Autos Includes dropping both 115/69 kv autotransformers. 8 AUSTIN NORTH 115 9 AUSTIN 69 10 BIGGS 115 11 CALIENTE 345 + Autos Includes dropping both 345/115 kv autotransformers 12 CALIENTE 115 + Autos Includes dropping both 345/115 kv autotransformers. 13 DIABLO 345 + Autos Includes dropping three 345/115 kv autotransformers. 14 DIABLO 115 + Autos Includes dropping three 345/115 kv autotransformers. 15 DYER 115 + Auto Includes dropping 115/69 kv autotransformer. 16 GLOBAL REACH 115 17 LANE 115 + Auto Includes dropping both 115/69 kv autotransformers. 18 LANE 69 + Auto Includes dropping both 115/69 kv autotransformers. AREA 10: EL_BUTTE- 19 LUNA 345 + Auto + GEN (3) SOCORROP 115 189.2 CUCHILLO 115 0.8889 To get this case to converge, load was reduce by 100 MW in BELEN_PG- southern New Mexico (Area 10) and 200 MW in EPE's system BERNARDO 115 176.9 HOT_SPRG 115 0.8887 300 MW (Area 11). EPE generation was at maximum output. EPI was BERNARDO- reduced from 812 to 425 MW. No attempt was made to raise SOCORROP 115 174.6 EL_BUTTE 115 0.8900 voltages in Area 10 by turning on shunt capacitors. ELBUT_US 115 0.8900 ELBUT_US 6.9 0.8900 NOTES 8

No. SUBSTATION OUTAGE (kv) 20 MONTOYA 115 21 MONTWOOD 115 22 NEWMAN 345 + Auto 23 NEWMAN 115 + Auto + ALL GEN (Case A) OVERLOADED FACILITY (kv) 130% (1) RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU LOAD SHED (4) NOTES Includes dropping the 345/115 kv autotransformer. Copper generation was OFF. ANTHONY2 23.9 0.8907 With Newman generation isolated (off), RG 6, 7, 8, & 9, Copper, & MPS Units 1&2 generation were at maximum output. No load was shed. To serve EPE load, EPI was raised from 812 to 1255 TRANSMTN_1 23.9 0.8914 MW in this case resulting in Path 47 imports of 929 MW. 24 NEWMAN 115 + Auto + ALL GEN (Case B) 25 ORO GRANDE 115 26 PICANTE 345 + Auto 27 PICANTE 115 + Auto 28 29 RIO GRANDE 115 + Autos + UNITS 8 & 9 RIO GRANDE 115 + ALL GEN 30 RIO GRANDE 69 + RG units 6 & 7 31 SALOPEK 115 LASCRUC1 23.9 0.8984 RG 7 off. With Newman generation isolated (off), RG 8 & 9, MESA_1 13.8 0.8841 Copper & MPS 1&2 generation were at maximum output. No load shed. To serve EPE load, EPI was raised from 812 to 1342 MILAGRO2 13.8 0.8902 MW in the case resulting in Path 47 imports of 916 MW. Both 115/69 kv autotransformers were dropped. With RG 8 & 9 generation off, RG 7, Copper, Newman, & MPS 1&2 generation were at maximum output. No load was shed. EPI was reduced from 812 to 760 MW. Both 115/69 kv autotransformers dropped. With all RG generation off including RG 6 & 7, all Newman, Copper, & MPS 1&2 generation were at maximum output. No load was shed. RG 8 & 9 generation was on. Both 115/69 kv autotransformers were dropped. 32 SCOTSDALE 69 + Auto Includes dropping the 115/69 kv autotransformer. 33 SPARKS 115 + Auto Includes dropping the 115/69 kv autotransformer. 34 SUNSET NORTH 115 + Auto Includes dropping the 115/69 kv autotransformer. 35 SUNSET 69 + Auto Includes dropping the 115/69 kv autotransformer. 36 VALLEY 69 37 VISTA 115 9

No. (1) Based on emergency Ampere or MVA ratings for transmission lines and transformers respectively. Used 130% of emergency rating as average overcurrent relay settings. (2) Any voltage below 0.90 per unit (PU) was improved with available area shunt capacitors. (3) Includes dropping LEF generation. This low-voltage scenario may cause load shedding at Luna and nearby areas from PNM's under-voltage load shed (UVLS) scheme to avoid voltage collapse at Luna. (4) MW load shed to allow powerflow case to converge. (5) El Paso Import (EPI) = 812 MW unless otherwise noted. (6) Afton Generation: OFF, PST: bypassed and Copper Generation: OFF -- unless otherwise noted. EPI - El Paso Imports, LEF - Luna Energy Facility, NWM - Newman, RG - Rio Grande Loss of local generation was normally replaced through Path 47 imports. GENERATING POWER STATION OUTAGE TABLE III: 2015 PLAN CASE NERC TPL-004, CATEGORY D # 10 OVERLOADED FACILITY (kv) 130% (1) LOSS OF ALL GENERATING UNITS AT A STATION RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU LOAD SHED (4) 1 NEWMAN (NWM) none none none 2 RIO GRANDE (RG) none none none 3 LUNA (LEF) none none none NOTES RG and Copper generation at maximum output. EPI increased from 812 to 1276 MW. Path 47 imports at 949 MW. Newman generation is at 90% of maximum output. Copper generation is off. EPI increased from 812 to 1142 MW. Path 47 imports at 797 MW. Newman generation at 90% of maximum output. RG generation at 52% of maximum output. Copper generation is off. (1) Based on emergency Ampere or MVA ratings for transmission lines and transformers respectively. Used 130% of emergency rating as average overcurrent relay settings. (2) Any voltage below 0.90 per unit (PU) was improved with available area shunt capacitors. (3) N/A (4) MW load shed to allow powerflow case to converge. (5) El Paso Import (EPI) = 812 MW unless otherwise noted. (6) Afton Generation: OFF, PST: bypassed, and Copper Generation: OFF -- unless otherwise noted. EPI - El Paso Imports, LEF - Luna Energy Facility, RG - Rio Grande Loss of local generation was normally replaced through Path 47 imports. 10

No. SUBSTATION OUTAGE (kv) 1 AFTON 345 2 AMRAD 115 3 ANTHONY 115 ARROYO 345 + 4 Autos ARROYO 115 + 5 Autos ASCARATE 115 + 6 Autos ASCARATE 69 + 7 Autos 8 AUSTIN NORTH 115 9 AUSTIN 69 TABLE IV: 2019 PLAN CASE NERC TPL-004, CATEGORY D # 8 LOSS OF A SUBSTATION (One Voltage Level plus Transformers) - 3 OR MORE FACILITIES OVERLOADED FACILITY (kv) 130% (1) Anthony-Newman 115 RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU LOAD SHED (4) NOTES Afton Generation was OFF. The future AFTON 345 kv design (AFTON_N 345 kv) precludes two lines from LUNA 345 kv by tying into the new AFTON_N 345 kv substation. The estimated in-service date for AFTON_N 345 kv is May 2016. Case required 35.4 MVAR from a fictitious SVG at ALAMOGCP 115 kv bus to converge. 132.2 Includes dropping both 345/115 kv autotransformers Includes dropping both 115/69 kv autotransformers. Includes dropping both 115/69 kv autotransformers. 10 BIGGS 115 11 CALIENTE 345 + Includes dropping both 345/115 kv Autos autotransformers. 12 CALIENTE 115 + Includes dropping both 345/115 kv Autos autotransformers. 13 DIABLO 345 + Autos Includes dropping three 345/115 kv autotransformers. 14 DIABLO 115 + Autos Includes dropping three 345/115 kv autotransformers. 15 DYER 115 + Auto Includes dropping both 115/69 kv autotransformers. 16 GLOBAL REACH 115 17 LANE 115 + Auto Includes dropping both 115/69 kv autotransformers. 18 LANE 69 + Auto Includes dropping both 115/69 kv autotransformers. 19 LUNA 345 + Auto + GEN (3) 11 300 MW To get the case to converge, load was reduce by 100 MW in southern New Mexico (Area 10) and 200 MW in EPE's system (Area 11). EPE generation was on at maximum output at Newman, RG 8 & 9, and MPS. EPI was reduced from 812 to 412 MW.

No. SUBSTATION OUTAGE (kv) MONTANA POWER 20 STATION 115 + ALL GEN 21 MONTOYA 115 22 MONTWOOD 115 23 NEWMAN 345 + Auto 24 25 NEWMAN 115 + Auto + ALL GEN (Case A) NEWMAN 115 + Auto + ALL GEN (Case B) 26 ORO GRANDE 115 27 PICANTE 345 + Auto 28 PICANTE 115 + Auto 29 RIO GRANDE 115 + Autos + UNITS 8 & 9 OVERLOADED FACILITY (kv) 130% (1) RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU CHAPARAL1 13.8 0.8860 CHAP_DIST_PV 13.8 0.8931 LOAD SHED (4) NOTES With MPS generation off, RG 7, 8, 9, Copper, and Newman generation were at maximum output. No load was shed. EPI was maintained at 812 MW. Includes dropping the 345/115 kv autotransformer. Copper generation was OFF. With Newman generation off, RG 7, 8, & 9, MPS Units 1-4, and Copper generation were at maximum output. No load was shed. To serve EPE load, EPI was raised from 812 to 1326 MW in this case resulting in an SNMI of 978 MW (exceeding its rating). CHAPARRAL 115 0.8788 RG 7 Off. With Newman generation off, RG 8 & 9, MPS CHAPARRAL1 13.8 0.8616 Units 1-4 and Copper generation were at maximum output. No load shed. To serve EPE load, EPI was raised from APOLLO 69 0.8968 812 to 1380 MW in the case resulting in an SNMI of 1032 PATRIOT1 13.8 0.8956 MW (exceeding its rating). Five NM buses were under 0.9 PU Gavilan 115-0.869, Ruidoso 115-0.869, C_Canyon CHAP_DIST_PV 13.8 0.8688 115-0.872, Blazer_T-0.884, C_Canyon 69-0.898 Both 115/69 kv autotransformers were dropped. With RG 8 & 9 generation off, RG 7, MPS, & Newman generation were at maximum output. Copper was off. No load was shed. 30 RIO GRANDE 115 + ALL GEN Both 115/69 kv autotransformers dropped. With all RG generation off, all Newman, MPS, and Copper generation were at maximum output. No load was shed. 31 RIO GRANDE 69 + UNIT 7 + AUTOS 32 SALOPEK 115 RG 8 & 9 were on. Both 115/69 kv autotransformers were dropped. 33 SCOTSDALE 69 + Auto Includes dropping the 115/69 kv autotransformer. 34 SPARKS 115 + Auto Includes dropping the 115/69 kv autotransformer. 35 SUNSET NORTH 115 + Auto Includes dropping the 115/69 kv autotransformer. 36 SUNSET 69 + Auto Includes dropping the 115/69 kv autotransformer. 37 VALLEY 69 38 VISTA 115 12

(1) Based on emergency Ampere or MVA ratings for transmission lines and transformers respectively. Used 130% of emergency rating as average overcurrent relay settings. (2) Any voltage below 0.90 per unit (PU) was improved with available area shunt capacitors. (3) Includes dropping LEF generation. This low-voltage scenario may cause load shedding at Luna and nearby areas from PNM's under-voltage load shed (UVLS) scheme to avoid voltage collapse at Luna. (4) MW load shed to help powerflow case converge. (5) El Paso Import (EPI) = 812 MW unless otherwise noted. (6) Afton Generation and Copper Generation OFF unless otherwise noted. No. GENERATING POWER STATION OUTAGE TABLE V: 2019 PLAN CASE NERC TPL-004, CATEGORY D # 10 OVERLOADED FACILITY (kv) 130% (1) LOSS OF ALL GENERATING UNITS AT A STATION RESULTS % EMERGENCY OVERLOAD VOLTAGE VIOLATION (2) PU LOAD SHED (4) NOTES 1 NEWMAN (NWM) none none none 2 RIO GRANDE (RG) none none none MPS, RG, and Copper generation at maximum output. To serve EPE load, EPI was raised from 812 to 1320 MW. Path 47 imports at 969 MW. MPS, Newman, & Copper generation at maximum output. 3 LUNA (LEF) none none none 4 MONTANA POWER STATION (MPS) none none none MPS generation at maximum output. Newman generation at 92% of maximum output. RG generation at 84% of maximum generation. Copper generation is off. Newman, RG, & Copper generation at maximum output. To serve EPE load, EPI was raised from 812 to 925 MW. Path 47 imports at 665 MW. (1) Based on emergency Ampere or MVA ratings for transmission lines and transformers respectively. Used 130% of emergency rating as average overcurrent relay settings. (2) Any voltage below 0.90 per unit (PU) was improved with available area shunt capacitors. (3) N/A (4) MW load shed to help powerflow case converge. (5) El Paso Import (EPI) = 812 MW unless otherwise noted. (6) Afton Generation and Copper Generation: OFF unless otherwise noted. EPI - El Paso Imports, LEF - Luna Energy Facility, RG - Rio Grande Loss of local generation was normally replaced through Path 47 imports. 13