TransCanyon Cross-Tie Transmission Project

Transcription

1 TransCanyon Cross-Tie Transmission Project WECC Path Rating Studies and Comprehensive Progress Report (Phase 1) Final Report Revision 1.0 July

2 Table of Contents Page Executive Summary Introduction and Project Description Study Overview Power Flow Case Description Power Flow Case Modifications PacifiCorp Generation Queue PacificCorp Generation Queue Dynamics Data Contingency Lists Study Methodology and Assumptions Cross-Tie Project Non-Simultaneous Study Results Summary of the Cross-Tie Non-Simultaneous Study Path Flows Summary of the Cross-Tie Non-Simultaneous Study Case Data Contingency List for the Cross-Tie Non-Simultaneous Analysis Diverged Cases for the Cross-Tie Non-Simultaneous Analysis Thermal Overloads for the Cross-Tie Non-Simultaneous Analysis Voltage Violations for the Cross-Tie Non-Simultaneous Analysis Transient Stability Results for the Cross-Tie Non-Simultaneous Analysis Reactive Margin Results for the Cross-Tie Non-Simultaneous Analysis % Flow Test for the Cross-Tie Project Path Independence Test for the Cross-Tie Project Conclusions for the Cross-Tie Non-Simultaneous Analysis Appendix 1 - Power Flow Plots Appendix 2 - Stability Plots 2

3 Executive Summary The Cross-Tie Transmission Project (Cross-Tie) is an EHV transmission intertie that is proposed to be constructed between the future Clover 500 kv substation (PacifiCorp) near Mona, UT and the Robinson Summit 500 kv substation (NV Energy) near Ely, NV. The anticipated in-service date for Cross-Tie is the fourth quarter of Cross-Tie is comprised of the following major transmission elements: a 213 mile, ACSR conductor, 500 kv transmission line, 50% total series compensation on the 500 kv line, and 2x90 MVAr shunt reactors at each end of the line. Three WECC power flow cases that represent three different seasonal operating conditions were selected for these Studies. These three cases are: 2026 Heavy Summer (26hs1a.sav) - approved , Heavy Winter (26HW1a.sav) - approved , and 2026 Light Spring (26LSP1Sa.sav) - approved The selected power flow cases were modified to include the Cross-Tie 500 kv Transmission Project, the 345 kv, 600 MVA Phase shifting transformers at Robinson Summit. About 4,400 MW of renewable generation in southeastern Wyoming (Aeolus area) and 5,500 MW of renewable generation in the Utah area were also added to the cases and are off-line unless needed to stress the Cross-Tie Project. For this analysis, Cross-Tie was primarily stressed by the generation in southeastern Wyoming (via the Aeolus South Path). The cases were also modified to model the Gateway West Project only including the new Aeolus-Anticline 500 kv section of Gateway West (Aeolus West) and the 230 kv system upgrades in the area. All 500 kv sections of the Gateway West Project west of Anticline Substation were removed from the case and the system model was changed to reflect the existing transmission system along this path. This Gateway West model represents what is included in the latest Pacificorp IRP (April 4, 2017) and is the same Gateway West model currently being used by CAISO to study the benefits of the submitted Interregional Transmission Projects (ITPs) in enabling imports of Wyoming renewable generation into California. The WECC Path Rating Catalog and engineering judgment was utilized to select contingencies that may impact the rating of the Cross-Tie Project. About 35 contingencies were selected to be run. 3

4 Conclusion The Cross-Tie Project will require an Accepted Rating. The studies show that the Cross- Tie Project can meet the NERC Reliability Standards/WECC Criteria and that the 1,500 MW Proposed Rating for the Cross-Tie Project is achievable. 4

5 1. Introduction and Project Description The Cross-Tie Transmission Project is an EHV transmission intertie that is proposed to be constructed between the future PacifiCorp-East (PACE) Clover 500 kv substation, expansion of the existing Clover 345kV substation, and NV Energy s Robinson Summit 500 kv substation. The anticipated in-service date for Cross-Tie is the fourth quarter of Figure 1-1 (following pages) provides a conceptual single line diagram of the Cross-Tie Transmission Project. Figure 1-2 is a map indicating the proposed route of the Project. Figure 1-3 is a map showing high voltage Transmission lines, adjacent Balancing Authority boundaries, and some of the WECC Rated Paths near the Cross-Tie Project. Cross-Tie is comprised of following transmission elements: A 500 kv line (213 miles, ACSR conductor) between the Clover and Robinson Summit substations, 50% total series compensation on the 500 kv line (29 ohms at each end), and 2x90 MVAr shunt reactors at each end of the line. It is anticipated that the maximum loading capability of Cross-Tie would be 1,500 MW. This value is dependent upon the complete build-out of the Robinson Summit-Harry Allen 500 kv Transmission Project (One Nevada Line). Commonly referred as SWIP- South, the complete build-out includes the following electric transmission facilities which do not exist today: Two phase-shifting transformers (345/345 kv, +/-48, 600MVA each) at NV Energy s Robinson Summit 345 kv bus: one connected to the Falcon-Robinson Summit 345 kv line, and one connected to the Gonder-Robinson Summit 345 kv line. 70% series compensation added to the Robinson Summit-Harry Allen 500 kv Line (35%/45 Ohms at each end of the line). The Harry Allen-Eldorado 500 kv Line (HAE, alternately known as the Southern Nevada Intertie Project or SNIP) will also need to be in-service. The HAE 500 kv Line is expected to be about 60 miles long, with one segment of 70% series-compensation at Harry Allen. The objective of this analysis is to determine a Proposed Rating for the Cross-Tie Project and identify potential transmission system impacts. 5

6 Figure 1-1: Cross-Tie Transmission Project Single Line Diagram 6

7 Figure 1-2: Proposed Cross-Tie Transmission Project Route 7

8 Figure 1-3: Cross-Tie Transmission Project High Voltage Transmission Lines Anticline Substation 8

9 2. Study Overview This section of the report describes the data sets and assumptions that were utilized in this analysis. All power flow and transient stability work complies with the NERC Reliability Standards and WECC Criteria. The General Electric Positive Sequence Load Flow (GEPSLF) program (version 19.0_02) was used for the analysis. 2.1 Power Flow Case Description Three recently approved base cases were selected for this analysis. The cases used are listed as follows: 2026 Heavy Summer (26hs1a.sav) - approved Heavy Winter (26HW1a.sav) - approved Light Spring (26LSP1Sa.sav) - approved The 2026 Heavy Summer case is a general 10-year case with typical flows throughout the WECC system. The case models expected peak load for the months of June-August. The case has median/high hydro conditions in the Pacific Northwest and a high thermal generation output in Southern California, Arizona, New Mexico, and Southern Nevada. Some of the significant path flows in this case are C0I 4525 MW, PDCI 2240 MW, IPP DC 620 MW, West of River 6415 MW, and East of River 2621 MW. The 2026 Heavy Winter case is a general 10-year case with typical flows throughout the WECC system. The case models expected peak load for winter conditions. The case has high hydro conditions in the Pacific Northwest and a high thermal generation output in the Pacific Northwest, Idaho, Montana, Colorado, and Wyoming. It has a medium level of thermal generation output in California, Arizona, New Mexico, and Southern Nevada. Some of the significant path flows in this are C0I 1620 MW, PDCI 1185 MW, IPP DC 590 MW, West of River 6825 MW, and East of River 3690 MW. The 2026 Light Spring case is a 10-year case with high wind generation dispatch. The case models expected minimum load for the months of March-May. The case has 30% wind output represented in all areas. Some of the significant path flows in this case are C0I 2800 MW, PDCI 2145 MW, IPP DC 320 MW, West of River 6035 MW, and East of River 3365 MW. 9

10 2.2 Power Flow Case Modifications The WECC power flow cases selected for this analysis had moderate to low flows on COI, PDCI, and the IPP DC line. Each seasonal power flow case was adjusted to stress these Paths to values near their respective Path limits. The final values for the power flow path flows and area data are listed in Sections 3.1 and 3.2. In addition, the cases all modeled the full build out of the Gateway West Project. The cases were modified to include only the following components associated with Gateway West and the underlying 230 kv system: Aeolus-Anticline 500 kv Line (including series capacitors), Three 500/230 kv, 1575/1764 MVA transformers at Aeolus, One 500/345 kv, 1000/1120 MVA transformer at Anticline, Two 345 kv, 700/784 MVA Phase shifters on the Bridger-Anticline 345 kv line, 500 kv reactive support at Aeolus and Anticline, TOT 4A Voltage Support Project, Standpipe 230 kv substation, One new 230 kv transmission line from Windstar to Aeolus and, Rebuild of the Dave Johnston-Difficulty-Shirley Basin-Aeolus 230 kv line All lines and equipment on the 500 kv system associated with the Gateway West Project that is west of Anticline Substation was removed from the case. The system model was changed to reflect the existing transmission system along this path. This Project scenario is currently being used by CAISO to study importing Wyoming renewable generation into California. The model for Gateway South was not changed. It was assumed that the Cross-Tie Project would primarily be loaded via flows on Gateway South by the generation in the Aeolus area. The WECC base case generation changes required to load up the Cross-Tie Project are described in later sections. 2.3 PacifiCorp Generation Queue The original WECC base cases that were selected for the analysis included about 1,440 MW of PacifiCorp queue generation in the area near Aeolus Substation. This generation is indicated in Table This generation was not changed and was left at the output specified in the original WECC cases. Table shows an additional 4,340 MW of new generation. This generation was added to the power flow case and is initially off-line. This generation is brought on-line as necessary to stress the Gateway West (Aeolus West) and Gateway South (Aeolus 10

11 South) Paths. A range of 2,200 to 2,700 MW of generation near Aeolus Substation is brought on-line to load up Aeolus South in each of the seasonal cases studied. Table shows about 1,000 MW of queue generation that has been suspended or deactivated. Some of this generation was included in previous studies that determined the 230 kv reinforcements required as part of the Gateway West Project. The power flow cases were checked to ensure that this generation was not modeled. Table shows about 5,500 MW of queue generation that was added to the Utah area. This generation was only used in cases where Cross-Tie and Aeolus South could not be stressed simultaneously by the Aeolus area generation. This situation occurred for the heavy summer case where Aeolus West and Aeolus South was heavily loaded and additional generation was required to stress Cross-Tie to the 1,500 MW limit. In this case, about a 160 MW reduction in Jim Bridger generation was required to eliminate violations on the Bridger West Path (Path 19). About 400 MW of renewable generation in the Utah area 1 was utilized to replace the Jim Bridger generation and maintain the area swing bus while maintaining flow of near 1,700 MW on Aeolus South and 1,500 MW on the Cross-Tie Project. In summary, the Aeolus area generation was primarily used to stress the Cross-Tie project. Some of the new generation added in the Utah area was used if there were limitations caused by using the Aeolus area generation alone. Power flow plots of the cases used for this CPR study are provided in Appendix 1. 1 New generation modeled at Sigurd and Emery was brought on-line. 11

12 Table Wyoming Area Queue Generation Modeled in the Original WECC Base Cases Q# Request Date Request Status Company Name Service Type Application Rules MW County ST Region Point of Interconnection Type 7 3/7/2001 In Service Rock River I, LLC ER LGI 50.0 Carbon WY PACE Foote Creek substation, 34.5 kv circuit Wind 8 3/8/2001 In Service Exxon Mobil Production Company NR LGI Lincoln WY PACE Monument Switching Station Natural Gas 12 8/27/2001 In Service FPL Energy Wyoming, LLC ER LGI Uinta WY PACE Longhollow Switching Station Wind 90 6/22/2006 In Service Mountain Wind Power, LLC NR LGI 60.0 Uinta WY PACE Muddy Creek substation Wind 96 10/9/2006 In Service Mountain Wind Power II, LLC NR LGI 79.5 Uinta WY PACE Muddy Creek substation Wind 117 1/18/2007 In Service PacifiCorp Commercial & Trading ER LGI 99.0 Carbon WY PACE Freezeout substation Wind 118 1/18/2007 In Service PacifiCorp Commercial & Trading ER LGI 19.5 Carbon WY PACE Freezeout substation Wind 126 3/5/2007 In Service PacifiCorp Commercial & Trading ER LGI Converse WY PACE Windstar substation near Dave Johnston Plant Wind 153 8/8/2007 In Service Top of the World Wind Energy, LLC ER LGI Converse WY PACE Dave Johnston-Yellowcake Line Wind /8/2007 In Service Chevron Global Generation NR SGI 19.5 Natrona WY PACE Sand Hills Line between Casper & Platte Junction Wind 119-A 1/29/2007 In Service PacifiCorp Commercial & Trading ER LGI Carbon WY PACE Foote Creek substation Wind 203 2/26/2008 In Service PacifiCorp Commercial & Trading ER LGI Carbon WY PACE Shirley-Basin substation on the Miners - Difficulty Line Wind 220 5/12/2008 In Service Three Buttes Windpower ER LGI 99.0 Converse WY PACE Latigo substation between Casper and Windstar line Wind 335 6/1/2010 In Service Pioneer Wind Park I, LLC NR LGI 40.0 Converse WY PACE Amassa substation, (DJ - Difficulty) Wind 306-A 12/3/2009 In Service Pioneer Wind Park I, LLC NR LGI 40.0 Converse WY PACE Amassa substation, (DJ - Difficulty) Wind Total

13 Table New Wyoming Area Queue Generation Added to the Base Cases Q# Request Date Request Status Company Name Service Type Application Rules MW County ST Region Point of Interconnection Type 272 5/14/2009 In Service PacifiCorp Commercial & Trading ER LGI Carbon WY PACE Proposed new substation on the Miners-Difficulty Line Wind 375 3/4/2011 In Progress Eurus Dry Creek Wind LLC ER LGI Carbon WY PACE Proposed Heward substation Wind 706 9/4/2015 In Progress N/A NR/ER LGI Carbon WY PACE Freezeout substation Wind 707 9/4/2015 In Progress N/A NR/ER LGI Carbon WY PACE Shirley Basin-Freezeout transmission line Wind 708 9/4/2015 In Progress N/A NR/ER LGI Carbon WY PACE Shirley Basin substation Wind /9/2015 In Progress N/A NR/ER LGI Converse WY PACE Windstar substation Wind /12/2015 In Progress N/A NR/ER LGI Converse WY PACE Yellowcake Antelope Mine transmission line Wind /29/2015 In Progress N/A NR/ER LGI Uinta WY PACE Canyon Compression-Railroad transmission line Wind /11/2015 In Progress N/A NR/ER LGI Albany WY PACE Freezeout substation Wind /13/2015 In Progress N/A NR LGI 80.0 Sweetwater WY PACE Raven substation Solar 783 8/3/2016 In Progress N/A NR/ER LGI 30.0 Natrona WY PACE Bar Nunn substation or Casper substation Solar 784 8/4/2016 In Progress N/A NR/ER LGI 80.0 Natrona WY PACE Casper substation Solar 785 8/4/2016 In Progress N/A NR/ER LGI Natrona WY PACE Casper substation Wind 789 8/8/2016 In Progress N/A NR LGI 74.9 Fremont WY PACE Thermopolis-Riverton transmission line Solar 801 9/20/2016 In Progress N/A NR LGI 80.0 Natrona WY PACE Bar Nunn substation Solar 802 9/20/2016 In Progress N/A NR/ER LGI 80.0 Natrona WY PACE Bar Nunn substation Solar 807 9/30/2016 In Progress N/A NR LGI 75.9 Carbon WY PACE Standpipe substation Wind /20/2016 In Progress N/A NR/ER LGI Uinta WY PACE Canyon Compression-Railroad transmission line Wind /5/2016 In Progress NR/ER LGI Carbon WY PACE High Plains - Foote Creek transmission line OR Foote Creek substation Wind /5/2016 In Progress NR/ER LGI Carbon WY PACE Aeolus substation Wind 409-A 1/26/2012 In Progress Intermountain Wind, LLC NR LGI 80.0 Albany WY PACE Freezeout substation Wind 409-B 1/26/2012 In Progress N/A NR LGI 80.0 Albany WY PACE Freezeout substation Wind 409-C 1/26/2012 In Progress N/A NR LGI 80.0 Albany WY PACE Freezeout substation Wind 409-D 1/26/2012 In Progress N/A NR LGI 80.0 Albany WY PACE Freezeout substation Wind Total

14 Table Wyoming Area Queue Generation that has Been Suspended or Deactivated Q# Request Date Request Status Company Name Service Type Application Rules MW County ST Region Point of Interconnection Type 199 2/20/2008 Suspended Simpson Ridge Wind Farm, LLC ER LGI 200 Carbon WY PACE Miners-Freezeout transmission line Wind 200 2/20/2008 Suspended Simpson Ridge Wind Farm, LLC ER LGI 100 Carbon WY PACE Miners-Freezeout transmission line Wind 201 2/20/2008 Suspended Simpson Ridge Wind Farm, LLC ER LGI 100 Carbon WY PACE Miners-Freezeout transmission line Wind 290-A 9/22/2009 Suspended Sweeney Park Wind Farm ER LGI Sweetwater WY PACE Rock Springs-Point of Rocks transmission line Wind 290-B 9/22/2009 Suspended Sweeney Park Wind Farm ER LGI Sweetwater WY PACE Rock Springs-Point of Rocks transmission line Wind 290-C 9/22/2009 Suspended Sweeney Park Wind Farm ER LGI 50.4 Sweetwater WY PACE Rock Springs-Point of Rocks transmission line Wind 306-B 12/3/2009 Deactivated N/A NR LGI 50.4 Converse WY PACE Amassa substation, (DJ - Difficulty) Wind 306-C 12/3/2009 Deactivated N/A NR LGI Converse WY PACE Amassa substation, (DJ - Difficulty) Wind Total Table.3-4 New Utah Area Queue Generation Added to the Base Case Q# Request Date Request Status Company Name Service Type Application Rules MW County ST Region Point of Interconnection Type 3 1/23/2001 In Service Utah Municipal Power Agency ER LGI 200 Salt Lake UT PACE West Valley substation, 138 kv Natural Gas 20 4/30/2003 In Service PacifiCorp Commercial & Trading ER LGI 280 Juab UT PACE Mona substation Natural Gas 21 4/30/2003 In Service PacifiCorp Commercial & Trading ER LGI 245 Juab UT PACE Mona substation Natural Gas 44 6/3/2004 In Service PacifiCorp Commercial & Trading ER LGI 535 Utah UT PACE Timp - Tri-City Line Natural Gas /27/2009 In Service PacifiCorp Energy ER LGI 625 Utah UT PACE New Steel Mill substation Natural Gas /25/2011 In Progress Sevier Power Company, LLC ER LGI 525 Sevier UT PACE Sigurd substation Natural Gas 710 9/17/2015 In Progress N/A NR/ER LGI 204 Kane UT PACE Sigurd-Glen Canyon Solar 763 6/22/2016 In Progress N/A NR/ER LGI 200 Iron UT PACE Three Peaks substation Solar 771 7/11/2016 In Progress N/A NR/ER LGI 525 Iron UT PACE Sigurd-Three Peaks transmission line Solar 774 7/11/2016 In Progress N/A NR/ER LGI Iron UT PACE Hickory Red Butte (Sigurd #2) transmission line Solar 777 7/13/2016 In Progress N/A NR/ER LGI 200 Emery UT PACE Emery substation Solar 787 8/8/2016 In Progress N/A NR/ER LGI 200 Emery UT PACE Emery-Sigurd #2 345 kv line OR Huntington-Sigurd 345 kv line Solar 788 8/8/2016 In Progress N/A NR/ER LGI 200 Emery UT PACE Emery-Sigurd #2 345 kv line OR Huntington-Sigurd 345 kv line Solar 805 9/30/2016 In Progress N/A NR LGI 136 Kane UT PACE Sigurd-Glen Canyon transmission line Solar /11/2016 In Progress N/A NR LGI 240 San Juan UT PACE Pinto substation Solar /8/2016 In Progress NR/ER LGI 525 Tooele UT PACE Clover-Oquirrh transmission line Solar /8/2016 In Progress NR/ER LGI 525 Utah UT PACE Camp Wiilliams-Mona Transmission Line Solar Total

15 2.4 PacificCorp Generation Queue Dynamics Data The WECC dynamics data associated with each of the WECC power flow cases was used as a starting point for this analysis. Type 3 generic wind turbine models and the newer generator/converter models for solar plants were used to represent the PacificCorp Queue generation additions in Wyoming and Utah. The same basic models were used for each plant with the MVA values changed to reflect the size of the plant modeled. Both wind and solar generation plants were assumed to have an MVA rating equal to MVA for each 2 MW of plant output. Figure shows the generic dynamic data used for wind generation. Figure shows the generic dynamic data used for solar generation. 15

16 Figure Generic Dynamic Data Assumptions for the Aeolus Area Wind Generation # # No repc_a model is included because the response of the plant controller is such that no response will be visible during the transient time frame. # Change mva=xxxx to a integer multiple of MVA. Each individual wind turbine has an MVA base of MVA. # regc_a "GNRIC WND G1" "1 " : #9 mva=xxxx "lvplsw" 1.0 "rrpwr" 0.65 "brkpt" 0.9 "zerox" 0.4 "lvpl1" 1.22 / "vtmax" 1.2 "lvpnt1" 0.2 "lvpnt0" 0.1 "qmin" -1.3 "accel" 0.5 "tg" "tfltr" 1 "iqrmax" 49.0 "iqrmin" "xe" 0 reec_a "GNRIC WND G1" "1 ": #9 "mvab" 0.0 "vdip" 0.9 "vup" 1.25 "trv" 0.02 "dbd1" "dbd2" 0.12 "kqv" 2.4 / "iqh1" 1.0 "iql1" -1.0 "vref0" 1.05 "iqfrz" 0.15 "thld" 0.0 "thld2" 0.0 "tp" 0.05 "qmax" "qmin" "vmax" 1.1 "vmin" 0.9 / "kqp" 5.0 "kqi" 5.0 "kvp" 5.0 "kvi" 5.0 "vref1" 0.0 "tiq" 0.01 "dpmax" 99.0 "dpmin" "pmax" "pmin" 0.0 "imax" 1.2 / "tpord" 0.01 "pfflag" 0 "vflag" 0 "qflag" 1 "pflag" 0 "pqflag" 0 "vq1" 0.0 "iq1" 0.0 "vq2" 0.20 "iq2" 1.0 "vq3" 0.50 "iq3" 1.0 / "vq4" "iq4" 1.0 "vp1" 0.0 "ip1" 0.0 "vp2" 0.20 "ip2" 0.50 "vp3" "ip3" 0.50 "vp4" "ip4" wtgq_a "GNRIC WND G1" "1 " : #9 "mvab" 0.0 "kip" 0.5 "kpp" 2.5 "tp" 0.4 "twref" 60.0 "temax" 1.1 "temin" 0 / "p1" 0.2 "spd1" 0.58 "p2" 0.4 "spd2" 0.72 "p3" 0.6 "spd3" 0.86 "P4" 0.8 "spd4" 1.0 "tflag" 0 wtgt_a "GNRIC WND G1" "1 " : #9 "mvab" 0.0 "ht" 6.7 "hg" 5.7 "dshaft" 1.5 "kshaft" 0.2 "wo" 1 wtga_a "GNRIC WND G1" "1 " : #9 "mvab" 0.0 "Ka" "Theta0" 0 wtgp_a "GNRIC WND G1" "1 " : #9 "mvab" 0.0 "kiw" 25.0 "kpw" "kic" 10 "kpc" 1 "kcc" 0.7 "tpi" 0.3 / "pimax" 27.0 "pimin" 0 "piratmx" 10.0 "piratmn"

17 Figure Generic Dynamic Data Assumptions for Solar Generation # # No repc_a model is included because the response of the plant controller is such that no response will be visible during the transient time frame. # Change mvab=xxxx to an integer multiple of MVA. Each individual solar inverter has an MVA base of MVA. The qmax, qmin, # pmax, and pmin variables of the reec_b model were changed to reflect PU output characteristics in respect to mvab of the regc_a model. # regc_a " GNRIC SLR G1" 0.48 "1 " : #9 mvab=xxxx "lvplsw" 1. "rrpwr" 10.0 "brkpt" 0.9 "zerox" 0.4 "lvpl1" 1.22 / "vtmax" 1.2 "lvpnt1" 0.8 "lvpnt0" 0.4 "qmin" -1.3 "accel" 0.7 "tg" 0.02 "tfltr" 0.02 "iqrmax" 999. "iqrmin" "xe" 0. reec_b " GNRIC SLR G1" 0.48 "1 " : #9 "mvab" 0. "vdip" -99. "vup" 99. "trv" 0.02 "dbd1" -0.5 "dbd2" 0.5 "kqv" 0. / "iqh1" 1.5 "iql1" -1.5 "vref0" 0. "tp" 0.5 "qmax" XXXX "qmin" XXXX "vmax" 1.1 "vmin" 0.9 "kqp" 0.0 "kqi" 0.1 "kvp" 0.1 / "kvi" 40. "tiq" 0.2 "dpmax" 999. "dpmin" "pmax" XXXX "pmin" 0. "imax" 1.3 "tpord" 0.4 "pfflag" 1. "vflag" 1. "qflag" 0. / "pqflag" 1. 17

18 2.5 Contingency Lists This Comprehensive Progress Report utilized the WECC Path Rating Catalog to select a few limiting contingencies for selected Paths that may be impacted by the Cross-Tie Project. Engineering judgment was utilized to select other contingencies that may impact the rating of the Cross-Tie Project. About 35 contingencies were selected. Some variations of several contingencies were also evaluated as part of this analysis. The contingency list is shown in Section Study Methodology and Assumptions Power flow analysis was used to evaluate thermal and voltage performance of the transmission system under NERC Category P0 (normal conditions with all elements inservice), and selected NERC Category P1 (emergency conditions with one element out of service), and selected NERC Category P2 (emergency conditions with multiple elements out of service). Contingencies were selected based on the limiting contingencies listed in the WECC Path Rating Catalog or by using engineering judgment. Normal thermal loading was typically reported when a transmission component was loaded above 95% of the appropriate Amp/MVA rating. Emergency thermal loading was typically reported when a transmission component was loaded over 95% of its appropriate emergency Amp/MVA rating and if there is a change in flow greater than 0.5% from the pre-contingency flow. For brevity, the report tables show data that exceed 99% of the applicable rating. In addition, selected transmission lines were recorded for every base and contingency case regardless of flow. Monitored normal voltage violations were limited to the conditions where per unit (PU) voltages were less than 0.95 or greater than Monitored emergency voltage violations were limited to the conditions where per unit voltages were less than 0.90 or greater than Voltage deviations less than or equal to -8% between the pre- and post-contingency states were listed in the report tables. The latest WECC Regional Criterion defined in TPL-001-WECC-CRT3 was used in evaluating the system performance for the dynamics analysis results. The elements of this criterion are: Dynamics results shall be stable and damped. Following fault clearing, the voltage shall recover to 80% of the pre-contingency voltage within 20 seconds of the initiating event for all P1 through P7 events, for each applicable BES bus serving load. 18

19 Following fault clearing and voltage recovery above 80%, voltage at each applicable BES bus serving load shall neither dip below 70% of precontingency voltage for more than 30 cycles nor remain below 80% of pre-contingency voltage for more than two seconds, for all P1 through P7 events. For Contingencies without a fault (P2.1 category event), voltage dips at each applicable BES bus serving load shall neither dip below 70% of pre-contingency voltage for more than 30 cycles nor remain below 80% of pre-contingency voltage for more than two seconds. All power flow and dynamics analysis was conducted with version 19.0_02 of General Electric s PSLF/PSDS/SCSC software. 3. Cross-Tie Project Non-Simultaneous Study Results The objective of this analysis was to determine if the Cross-Tie Project can achieve a Proposed Rating of 1,500 MW. The three seasonal WECC base cases discussed in previous sections were modified such that Cross-Tie flows were at the proposed rated value. Cross-Tie was primarily loaded via Aeolus South and the Aeolus area renewable generation. 3.1 Summary of the Cross-Tie Non-Simultaneous Study Path Flows Table shows selected path flows for each of the seasonal cases evaluated. The Cross-Tie, Aeolus South, and Aeolus West flows and some of the other heavily loaded Paths are indicated in the shaded sections of the tables. The MW loading and percent loading are also provided for other selected Paths 2. 2 Rating 1 typically refers to the Path rating for the direction that the flow is usually a concern. Rating 2 refers to the Path rating in the opposite direction. The applicable path rating is automatically selected based on the flow direction and the percent loading is calculated based on that flow direction. If no rating is indicated, the percent loading is calculated using the change in flow and original flow from the base case. 19

20 Table Selected Path Flows 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring Path No Path Name Rating 1 Rating 2 MW Flow % Rating MW Flow % Rating MW Flow % Rating 3 NORTHWEST - CANADA MONTANA - NORTHWEST IDAHO - NORTHWEST MIDWAY - LOS BANOS IDAHO - SIERRA BORAH WEST MONTANA - IDAHO BRIDGER WEST SOUTHWEST OF FOUR CORNERS FOUR CORNERS 345/ PG&E - SPP NORTHERN - SOUTHERN CALIFORNIA IPP DC LINE INTERMOUNTAIN - MONA 345 KV INTERMOUNTAIN - GONDER 230 KV TOT 1A TOT 2A PAVANT; INTRMTN - GONDER 230 KV BONANZA WEST TOT 2C TOT 4B TOT TOT SDG&E - CFE NORTHERN NEW MEXICO (NM2) EAST OF COLORADO RIVER (EOR) BROWNLEE EAST ELDORADO - MEAD 230 KV LINES ELDORADO - MCCULLOUGH 500 KV PACIFIC DC INTERTIE (PDCI) COI NORTH OF JOHN DAY MIDPOINT - SUMMER LAKE ALTURAS PROJECT TOT 2B TOT 2B MONTANA SOUTHEAST Southern CA Imports Cross Tie Aeolus South Aeolus West SWIP South Harry Allen-Eldorado (SNIP) Path C (Post-Gateway) TOT 3 (Wayne Child) TOT 4A (Post-Gateway)

21 3.2 Summary of the Cross-Tie Non-Simultaneous Study Case Data Table shows the case area data for each of the seasonal case flows evaluated. The original plan for this analysis was to stress the Cross-Tie Project by increasing generation in the Aeolus area and decreasing generation in Southern California. However, the selected WECC base cases were moderately/lightly loaded on some Paths into California that were desired to be stressed during the studies. Adjustments made to stress these Paths resulted in low generation levels in Southern California 3. Since generation levels were high in Arizona, Cross-Tie was stressed to 1,500 MW by increasing Aeolus area generation in Southeastern Wyoming (Area 65 PACE) and decreasing generation in the Arizona area (while maintaining COI flow). The Light Spring case model initially had low generation levels in California. Obtaining high imports on COI/PDCI and the IPP DC line required even more of a reduction of the California area generation. To accommodate the flows desired to stress these paths and the Cross-Tie Project, the load in California and across the Desert Southwest was increased by around 5%. 3 COI (Path 66) and PDCI (Path 65) were stressed primarily by increasing generation in the Northwest (Area 40) and decreasing Southern California (Areas 22, 24, 26) generation. The IPP DC (Path 27) was stressed primarily by increasing generation at Intermountain or in the Utah area (PACE), and decreasing generation in the immediate LADWP area. 21

22 Table Summary of Case Data 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring AREA AREA NAME P Gen P Load P Loss P Intchg P Gen P Load P Loss P Intchg P Gen P Load P Loss P Intchg 10 NEW MEXICO 3,432 3, ,141 2, ,214 2, EL PASO 1,576 2, ,004 1, , ARIZONA 24,265 23, ,330 16, ,141 12,326 10, , NEVADA 6,540 6, ,425 3, ,511 2, MEXICO-CFE 3,295 3, ,917 1, ,289 1, IMPERIALCA 2,484 1, ,029 1, SANDIEGO 4,865 5, ,108 3, ,450 2,085 2, SOCALIF 18,858 23, ,844 5,774 16, ,785 2,970 11, , LADWP 6,254 7, ,952 4,179 4, ,314 2,603 2, PG AND E 25,790 28, ,380 17,711 19, ,886 12,145 13, , NORTHWEST 33,752 27,674 1,226 4,853 41,239 32,711 1,452 7,156 24,493 17, , B.C.HYDRO 11,993 8, ,948 13,112 11, ,529 6, FORTISBC , ALBERTA 14,447 14, ,479 15, ,599 7, IDAHO 2,339 4, ,125 1,834 2, ,171 1,111 1, MONTANA 3,134 2, ,109 2, ,322 1, , WAPA U.M SIERRA 2,553 2, ,925 2, ,432 1, PACE 14,339 9, ,820 12,019 8, ,577 10,717 7, , PSCOLORADO 8,695 8, ,629 6, ,873 4, WAPA R.M. 6,850 6, ,321 5, ,317 3, , Contingency List for the Cross-Tie Non-Simultaneous Analysis The contingencies selected for the non-simultaneous analysis were compiled from a previous preliminary Cross-Tie analysis and the WECC Path Rating catalog. The previous analysis addressed contingencies near the Cross-Tie interconnection points. Limiting contingencies listed in the WECC Path Rating catalog were also selected for Paths that were anticipated to have a simultaneous relationship with the Cross-Tie Project. The contingency list for the Cross-Tie non-simultaneous analysis is provided in Table

23 Table Contingency List NERC No Contingency Description P0 0 Base Case - Normal Conditions P Trip Cross-Tie 500 kv Transmission Line 20 Trip Robinson Summit-Falcon 345 kv Transmission Line 30 Trip Robinson Summit-Gonder 345 kv Transmission Line 60 Trip Aeolus South 500 kv Transmission Line (No RAS) 60.1 Trip Aeolus South 500 kv Transmission Line (600 MW Gen Tripping) 70 Trip SWIP South 500 kv Transmission Line 80 Trip Aeolus-Anticline #1 500 kv Transmission Line (No RAS) 80.1 Trip Aeolus-Anticline #1 500 kv Transmission Line (Trip 600 MW Gen) 100 Trip Intermountain-Gonder #1 230 kv Transmission Line 110 Trip Intermountain-Mona #1 345 kv Transmission Line 120 Trip Intermountain-Mona #2 345 kv Transmission Line 140 Trip Oseola-Black Rock 230 kv Transmission Line 150 Trip Sigurd-Three Peaks #1 345 kv Transmission Line 160 Trip Three Peaks-Red Butte #1 345 kv Transmission Line 170 Trip Huntington-Pinto #1 345 kv Transmission Line 180 Trip Pinto-Four Corners #1 345 kv Transmission Line 190 Trip Red Butte-Harry Allen 345 kv Transmission Line 250 Populus-Borah #1 345 kv line 260 Populus-Borah #2 345 kv line 270 Populus-Kinport #1 345 kv line 290 Populus-Bridger #1 345 kv line 300 Populus-Bridger #2 345 kv line P Trip Robinson Summit 500/345 kv Transformer 50 Trip Clover 500/345 kv Transformer 50.1 Trip Clover 500/345 kv Transformer (Reactive Support) P Intermountain-Adelanto DC Outage 230 PDCI Bi-Pole Outage P Palo Verde Double Generator Outage P Trip Intermountain-Mona 1 & kv Transmission Lines (With RAS) 210 Table Mountain-Tesla & Table Mountain-Vaca Dixon 500kV Lines 280 Populus-Borah 1&2 345 kv lines (Bridger RAS) 310 Populus-Bridger 1&2 345 kv lines (Bridger RAS) 23

24 3.4 Diverged Cases for the Cross-Tie Non-Simultaneous Analysis Table indicates contingency cases that have numerical divergence issues for the non-simultaneous cases with Cross-Tie loaded to 1,500 MW. The diverged case indicated in the table consists of a variation of the contingency where the associated Remedial Action Scheme (RAS) is not implemented. The loss of Aeolus South or Aeolus West 500 kv lines requires a scheme to trip 600 MW of generation in the Aeolus area. The cases where this scheme is implemented solve without issue. Table Summary of Diverged Cases NERC No Contingency Description 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring P Trip Aeolus South 500 kv Transmission Line (No RAS) Diverged Diverged Solved 3.5 Thermal Overloads for the Cross-Tie Non-Simultaneous Analysis Table indicates thermal overload issues for the contingencies selected to analyze the non-simultaneous 1,500 MW loading for the Cross-Tie Project. As indicated in Table for the 2026 Heavy Summer case, The Kinport-Populus 345 kv line is loaded to 99% of its emergency rating for the N-2 loss of the Populus-Borah 345 kv lines (contingency trips two Bridger units). Note that Bridger generation was reduced by about 160 MW from the maximum plant output to accommodate the new Aeolus area generation and maintain limits on the Bridger/Anticline West and the Aeolus South Paths. Another contingency that can limit Bridger generation and/or the Aeolus area generation in the transmission configuration studied is the N-2 loss of the Bridger- Populus 345 kv lines. Both of these contingencies can give similar results and the limiting contingency could vary based on the system conditions. In addition, the SWIP South contingency caused overloads on the Summit Intertie (Path 24) for some of the cases studied. These issues were mitigated in this study by adjusting the California Substation phase shifter. The loading on the Summit Intertie is impacted by the SWIP South Project and should be studied in greater detail in later studies. It should also be noted that emergency or seasonal ratings in this area are not provided for the overloaded equipment in the WECC cases selected for the analysis. If higher ratings can be acquired, it is possible that these issues could be mitigated. 24

25 3.6 Voltage Violations for the Cross-Tie Non-Simultaneous Analysis Table indicates that there are no voltage violation issues for the contingencies selected to analyze 1,500 MW of non-simultaneous flow on the Cross-Tie Project. The loss of the Aeolus South 500 kv line without tripping 600 MW of Aeolus area generation resulted in diverged cases for the 2026 Heavy Summer and Heavy Winter cases. These cases likely diverged due to very low voltages in the Aeolus area without this generation tripping scheme implemented. 25

26 Table Summary of Thermal Overloads MVA 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring NERC No Contingency Description Monitored Branch Section Rating P Dir Area % Rating % Rating % Rating P Populus-Borah 1&2 345 kv lines (Bridger RAS) KINPORT POPULUS Ckt # ( Table Summary of Voltage Violations 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring NERC No ContingenBus Name Area Base VPU Cont VPU % Dev Base VPU Cont VPU % Dev Base VPU Cont VPU % Dev No Voltage Violations 26

27 3.7 Transient Stability Results for the Cross-Tie Non-Simultaneous Analysis Dynamics analysis was performed for a few selected contingencies. The selected contingencies include the loss of the Cross-Tie Project and a few other contingencies identified when performing the power flow studies. The selected contingencies are listed in Table Table Transient Stability Contingencies NERC No Contingency Description P Clover 500 kv 3PH Flt - Trip Cross-Tie 500 kv Line (Flash Capacitors) P Aeolus 3 PH Fault - Trip Aeolus South 500 kv Transmission Line (No RAS) P Aeolus 3 PH Fault - Trip Aeolus South 500 kv Line (600 MW Gen Trip) P Robinson 500 kv 3PH Flt - Trip SWIP South 500 kv Line P Aeolus 3 PH Fault - Trip Aeolus-Anticline 500 kv Transmission Line (No RAS) P Aeolus 3 PH Fault - Trip Aeolus-Anticline 500 kv Line (600 MW Gen Trip) P Table Mountain-Tesla & Table Mountain-Vaca Dixon 500kV Lines P PDCI Bi-Pole Outage P Palo Verde Double Generator Outage Stability plots are included in Appendix 2. The analysis concluded that there were no stability issues. All cases were stable and sufficiently damped and there were no voltage deviation or frequency violations. Note that the voltage and frequency relay models were disabled for the new Aeolus area generation that was added to the case. These models tripped this generation due to high voltage or frequency immediately when a fault at Aeolus is cleared. This may be due to numerical issues with the models, or in the case of the voltage, may require different relay settings or the addition of reactive support. This issue is not an issue related to the Cross-Tie Project and should be resolved as part of the Aeolus West and Aeolus South Projects. 3.8 Reactive Margin Results for the Cross-Tie Non-Simultaneous Analysis The reactive margin was determined for several buses for the same contingencies identified in Section 3.7. The buses where margin is monitored were selected by evaluating the largest voltage deviations while performing the studies. The reactive margin for these buses and contingencies is indicated in Table The reactive margin 27

28 criteria for each of the selected buses is currently unknown 4 a value of -400 MVAR was used to highlight the buses with the lowest reactive margin. There do not appear to be any reactive margin issues for the cases studied. 4 The determination of margin criteria would require developing load sensitivity cases of 2.5% and 5% in the various areas where the voltage was impacted. Determining these criteria is outside of the current study scope. 28

29 Table Reactive Margin Analysis 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring NERC NO CONTINGENCY DESCRIPTION QV BUS V PU MVAR V PU MVAR V PU MVAR P0 0 Base Case - Normal Conditions GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER P Trip Cross-Tie 500 kv Transmission Line GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER Trip Aeolus South 500 kv Transmission Line (No RAS) GONDER Diverged 1.00 Diverged HA PS Diverged 1.01 Diverged INTERMT Diverged 1.00 Diverged MONTROSE Diverged 0.93 Diverged OSCEOLA Diverged 1.00 Diverged PINTO Diverged 1.03 Diverged ROBINSON Diverged 0.99 Diverged SIGURDPS Diverged 1.04 Diverged BIG EDDY Diverged 1.07 Diverged MALIN Diverged 1.09 Diverged CAPTJACK Diverged 1.09 Diverged TABLE MT Diverged 1.07 Diverged TESLA Diverged 1.06 Diverged RINALDI Diverged 1.07 Diverged SYLMARLA Diverged 1.03 Diverged TOLUCA Diverged 1.06 Diverged LATHAM Diverged 1.01 Diverged AEOLUS Diverged 1.05 Diverged CLOVER Diverged 1.07 Diverged Trip Aeolus South 500 kv Transmission Line (600 MW Gen Tripping) GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER

30 Table Reactive Margin Analysis (Continued) 2026 Heavy Summer 2026 Heavy Winter 2026 Light Spring NERC NO CONTINGENCY DESCRIPTION QV BUS V PU MVAR V PU MVAR V PU MVAR P Trip SWIP South 500 kv Transmission Line GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER Trip Aeolus-Anticline #1 500 kv Transmission Line (No RAS) GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER Trip Aeolus-Anticline #1 500 kv Transmission Line (Trip 600 MW Gen) GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER P PDCI Bi-Pole Outage GONDER HA PS INTERMT MONTROSE OSCEOLA PINTO ROBINSON SIGURDPS BIG EDDY MALIN CAPTJACK TABLE MT TESLA RINALDI SYLMARLA TOLUCA LATHAM AEOLUS CLOVER