WECC Path Updates to 2030 Topology

November 20, 2019

Tyler Butikofer Staff Engineer Process

▪ Compare the 2028 ADS PCM path branch definition to the 30HS1a1 PF path branch definition, looking for: • Change in branch topology • Difference in defined branch direction ▪ Compare the 2028 ADS PCM path ratings to the 30HS1a1 PF path ratings ▪ Used the 2019 Path Rating Catalog to verify branches and ratings

2 Branch Changes/Inconsistencies

▪ Path 1. Alberta - British Columbia • Midpoint bus removed from Bennett-Cranbrook ▪ Path 3. Northwest to British Columbia • Midpoint buses added to all four branches ▪ Path 5. West of Cascades-South • Midpoint bus added to Big Eddy-McLoughlin • N. Bonneville-Midway branch is not in 30 HS1a1 ◦ 2028 PCM branch is between N. Bonneville-Little Buck ▪ Path 8. Montana to Northwest • Broadview-Garrison #2 branch ID changed from 1 to 2

3 Branch Changes/Inconsistencies

▪ Path 17. Borah West Upgrade (Gateway West) • Kinport-Midpoint in removed due to upgrade and two other included branches added ◦ Branch still in 30HS1 ▪ Path 33. Bonanza West • 30HS1 removed a bus in between Upalco-Carbon ▪ Path 39. TOT 5 • Incorrect branch in 30HS1 for North Park-Terry Ranch Rd • Incorrect branch for Hayden-Gore Pass 230 kV branch in both 30HS1 and 2028 PCM • Incorrect branch in 30HS1 for Hopkins-Malta

4 Branch Changes/Inconsistencies

▪ Path 40. TOT 7 • Bus number changed in 30HS1, direction incorrect also ▪ Path 46. West of • Midpoint buses added to three branches ▪ Path 47. Southern New Mexico (NM1) • Two bus numbers changed ▪ Path 48. Northern New Mexico (NM2) • 345/115 kV transformers’ bus numbers changed • Walsenburg-Gladstone has another bus in between

5 Branch Changes/Inconsistencies

▪ Path 49. East of the Colorado River • Midpoint bus added to Palo Verde-Colorado River ▪ Path 71. South of Allston • Lewis & Clark-Astoria Tap branch is incorrect in both 30HS1 and 2028 PCM • Rivergate-Trojan bus number changed, branch doesn’t go between Rivergate and Trojan • Horizon-St. Marys-Trojan doesn’t have a branch in 30HS1 • Multiple branches do not seem to be the correct branches

6 Branch Changes/Inconsistencies

▪ Path 76. Alturas Project • Midpoint bus added for three winding transformer ▪ Path 77. Crystal-Harry Allen • Midpoint bus added for three winding transformer ▪ Path 78. TOT 2B1 • Sigurd-Glen Canyon is missing in the path definition in both 30HS1 and 2028 PCM

7 Branch Direction Corrections

▪ . Midway-Los Banos • 30HS1 – Two 500 kV Gates-Mustang ▪ Path 33. Bonanza West • 30HS1 – 345 kV Bonanza to Mona ▪ Path 39. TOT 5 • 30HS1 – 138 kV Gorepass to Hayden ▪ Path 81. Southern Transmission Interface • 30HS1 – Two 230 kV branches, one 138 kV Branch • 230 kV McCullough to • 230 kV Northwest to Desert View • 138 kV Indian Springs to Mercury

8 Path Ratings

30HS1 2028 ADS PCM 2019 Path Rating Catalog Summer Summer Winter Winter Forward Backward Forward Backward Forward Backward Forward Backward Path Limit Limit Limit Limit Limit Limit Limit Limit P05 West of Cascades-South 7,200 -7,200 5,738 -5,738 5,930 -5,930 7,600 -7,600 P17 Borah West 4,450 -1,600 4,450 -4,450 2,557 -1,600 2,557 -1,600 P17 Borah West (w/ Gateway) 4,450 N/A 4,450 N/A P19 Bridger West 2,400 -600 4,100 -2,300 2,400 -1,250 2,400 -1,250 P19 Bridger West (w/ Gateway) 4,100 N/A 4,100 N/A P20 Path C 1,600 -1,250 2,250 -2,250 1,600 -1,250 1,600 1,250 P20 Path C (w/ Gateway) 2,250 -2,250 2,250 -2,250 P37 TOT 4A 810 0 1,025 -1,025 1,025 N/A 1,025 N/A P37 TOT 4A (w/ Gateway) 2,175 N/A 2,175 N/A P38 TOT 4B 680 0 880 -880 880 N/A 880 N/A P65 Pacific DC Intertie (PDCI) 3,100 -3,100 3,220 -3,100 3,220 -3,100 3,220 -3,100 P71 South of Allston 3,980 -1,115 3,100 -1,480 2,725 1,170 3,100 1,480 P73 North of John Day 7,700 -7,700 7,800 -7,800 7,800 -7,800 7,700 -7,700 P78 TOT 2B1 600 -600 647 -700 647 -700 647 -700

9 Path Ratings Next Steps

▪ Reach out to owners for months to assign to summer, winter, and spring ratings ▪ What should we do for ratings for direction not rated? • PF leaves it unrated

10 Contact: Tyler Butikofer Staff Engineer [email protected]

11