Natural Gas Disruption Task Force Findings January 15, 2020 Doug Tucker Tyler Butikofer
Study Purpose ▪ Outage of the southern line of the El Paso Natural Gas Pipeline in the Desert Southwest • Identify transmission constraints and potential unserved load using the PCM • Identify potential voltage and stability risks in the Southern California and Arizona areas using a power flow and dynamic program • Identify the threshold for unavailable gas-fired capacity before experiencing unserved load, and voltage or dynamic stability constraints 2
Work Flow PCM Work PF Work WECC Gas-Electric Interface Study Model generation Run 2028 ADS Export August 24, unavailable and PCM with 7:00 to 8:00 PM Unavailable identify the threshold Northern from 2028 ADS Generation List PCM Phase 1 V2.2 for having unserved California units in from Gas- in PSLF format load service Electric Interface Study Solve the Starting at the export hour Eastern Arizona Apply Generation In PSLF border and moving List to 2028 ADS toward California, PCM Phase 1 V2.2 model generators and run case unavailable Starting at the No Eastern Arizona border and moving toward California, Identify Worst hour for model generators Is there Unserved Load unavailable unserved load? No Yes Has a voltage/ Unserved load dynamic stability threshold identified issue occurred? Yes Voltage/dynamic stability limit identified 3
Load and Loss Differences ▪ Power flow took PCM output on August 24, 7:00 p.m. to 8:00 p.m. • Set generation and loads in power flow • System losses are different between PCM and power flow models Model Generation Load System Losses PCM 153,964 150,796 3,167 Power Flow 153,963 149,990 3,941 4
Path Comparisons for Stating Case Path Number and Name Power Flow PCM Flows Path Limits Flows (MW) (MW) (MW) -2,083 -3,150 3 Northwest – Canada -1,792 861 2,000 15 Midway – Los Banos 838 22 Southwest of Four Corners 7,098 7,279 2,325 27 IPP DC Line 883 881 2,400 7,279 11,200 46 West of Colorado River (WOR) 7,098 3,332 10,100 49 East of Colorado River (EOR) 3,200 50 Cholla – Pinnacle Peak 529 567 1,200 51 Southern Navajo 70 62 2,800 913 913 3,220 65 Pacific DC Intertie (PDCI) 731 1,033 4,800 66 California Oregon Intertie For Path 15, the transfer limit ranges from 2,000-3,265 MW for north-to-south direction. For the purpose of this study, the limit was set at 2,000 MW. 5
PCM Study Assumptions ▪ Generation taken out was indicated by the WECC Gas-Electric Interface study ▪ Generation was removed from the New Mexico/Arizona boarder moving west 6
Unavailable Capacity and Unserved Load of Threshold PCM Case ▪ Once 10,688 MW of gas-fired capacity was lost in Arizona, 264 of unserved load was observed in Arizona Path Number and Name Flow (MW) Limit (MW) 1 Alberta – British Columbia 1,000 1,000 15 Midway – Los Banos 2,000 2,000 2,325 22 Southwest of Four Corners 1,512 2,400 27 IPP DC Line 1,307 30 TOT 1A 650 650 46 West of Colorado River (WOR) 1,496 11,200 -10,100 49 East of Colorado River (EOR) -3,339 17 52 Silver Peak – Control 17 65 Pacific DC Intertie (PDCI) 2,457 3,220 66 COI 549 4,800 325 83 Montana Alberta Tie Line 325 For Path 15, the transfer limit ranges from 2,000-3,265 MW for north-to-south direction. For the purpose of this study, the limit was set at 2,000 MW. 7
Power Flow Assumptions ▪ Generation taken out was indicated by the WECC Gas-Electric Interface study ▪ Generation was removed from the New Mexico/Arizona boarder moving west ▪ Post Transit Simulation was used in power flow simulations • PSLF was used to study the snapshot and is unable to run a simulation of this magnitude • Allowed some of the equipment to switch on or off • Generation lost was re-dispatched through the system 8
~6800 MW of Generation Lost ▪ Path 3 Northwest - Canada, has exceeded (-3153 MW) its path rating of -3150 MW ▪ Path 83 MATL, is 29 MW over its limit • Because this is a phase shifter, the operators would control this flow. The 29 MW would flow down Path 3. ▪ Voltage at a 345-kV bus in Colorado dropped to 0.937 from 1.41 pu (10%) ▪ Observed 467 buses with at least a 5% change or greater 9
~8513 MW of Generation Lost ▪ Path 3 and Path 15 have exceeded the max ratings of -3150 and 2000 MW ▪ The system has lost 77 Generation units ▪ Voltage at a 345-kV bus in Colorado dropped by 17.6% ▪ Observed 1724 buses with at least a 5% or greater change • 362 bus are over 10% change 10
Path Flow with ~8513 MW of Generation lost Path Number and Name Pre-Flow Post-Flow Path Limit 3 Northwest – Canada -1,792 -3,572 -3,150 838 2,350 2,000 15 Midway – Los Banos 1,038 1,288 2,325 22 Southwest of Four Corners 27 IPP DC Line 883 883 2400 46 West of Colorado River (WOR) 7,098 2,226 11,200 3,200 -2,436 10,100 49 East of Colorado River (EOR) 50 Cholla – Pinnacle Peak 529 485 1,200 51 Southern Navajo 70 1,718 2,800 65 Pacific DC Intertie (PDCI) 913 3,100 3,220 731 2,327 4,800 66 COI For Path 15, the transfer limit ranges from 2,000-3,265 MW for north-to-south direction. For the purpose of this study, the limit was set at 2,000 MW. 11
Contingencies Runs ▪ Started with the case that has lost ~5315 MW of generation. ▪ Created a dynamics file to run the following Contingencies • Single Palo Verde outage • Loss of the Bi-Pole PDCI 12
Palo Verde Contingency Results ▪ No TPL-001 dynamic Voltage Criteria was violated in either contingency ▪ Frequency dropped to 59.905 for the loss of the single Palo Verde Unit ▪ Path 3 Northwest – Canada: increases to ~- 3130 MW with a limit of -3150 MW ▪ Path 15 Midway – Los Banos: increases to ~1800 MW with a limit of 2000 MW 13
Bi-Pole PDCI Contingency Results ▪ No TPL-001 dynamic Voltage Criteria was violated in either contingency. ▪ Not a Frequency Event. ▪ Loss 44 MW of load in the New Mexico area ▪ Path 3 Northwest – Canada: increases to ~-3130 MW with a limit of -3150 MW ▪ Path 15 Midway – Los Banos: increases to ~2700 MW which has exceeded the limit of 2000 MW ▪ Path 26 Northern to S California: increases to ~4000 MW which has a limit of 4000 MW 14
Summary ▪ Before the total loss of 24,000 MW • Transmission constraints were observed • The PF analysis shows at approximately 8,300 MW, the Western Interconnection is potentially at risk of low voltages • The PCM shows at approximately 10,600 MW, potential risk of unserved energy 15
Recommendations ▪ Natural gas, and fuel availability, should be considered when planning the bulk power system as illustrated by this extreme scenario 16
Report Approval Request for approval of the 2019 NGDTF Reliability Assessment Report 17
Contact: Doug Tucker dtucker@wecc.org Tyler Butikofer tbutikofer@wecc.org 18
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