2021 & 2025 Final LCR Study Results Sierra Area Ebrahim Rahimi - PowerPoint PPT Presentation

2021 & 2025 Final LCR Study Results Sierra Area Ebrahim Rahimi Lead Regional Transmission Engineer Stakeholder Call April 13, 2020 ISO Public ISO Public

Sierra Area Transmission System & LCR Sub-areas Legend: Table Mountain Sierra Overall 230 kV 230 kV 115 kV Table Mountain 60 kV 60 kV Caribou 115 kV Palermo 230 kV Drum 115 kV Sierra Area Colgate Summit Palermo 230 kV 115 kV 115 kV Placer Spaulding 115 kV Pease 60 kV Summit 60 kV Pease E. Marysville 60 kV Bogue 115 kV Subarea 115 kV Placer Pease E. Nicolaus Subarea 115 kV 115 kV Rio Oso 115 kV Gold Hill Drum – Rio Oso – Drum Subarea Subarea Rio Oso 230 kV South of South of Rio Oso Atlantic Subarea Palermo Brighton 230 kV 230 kV Gold Hill Subarea 230 kV Lodi Lake 230 kV 230 kV Lockeford 230 kV Eight Mile Rd 230 kV Bellota 230 kV Slide 2 ISO Public

New major transmission projects Project Name Expected ISD Year 2021 Pease 115/60 kV Transformer Addition Mar-20 South of Palermo 115 kV Reinforcement Project Apr-20 (Pease to Palermo Line) Year 2025 Rio Oso 230/115 kV Transformer Upgrades Jun-22 Rio Oso Area 230 kV Voltage Support Jun-22 South of Palermo 115 kV Reinforcement Project Nov-22 (Pease to Rio Oso Line) East Marysville 115/60 kV Dec-22 Gold Hill 230/115 kV Transformer Addition Dec-24 Slide 3 ISO Public

Power plant changes Additions: • No new resource addition Retirements: • Greenleaf 1 Slide 4 ISO Public

Sierra Area Overall: Load and Resources Load (MW) 2025 Generation (MW) 2025 2021 2021 Gross Load 1,789 1,849 Market/ Net Seller/ Battery 920 920 AAEE -7 -16 Solar 5 5 Behind the meter DG 0 0 Wind 0 0 Net Load 1,782 1,833 Muni 1,142 1,142 Transmission Losses 84 84 QF 41 41 Future preferred resource Pumps 0 0 0 0 and energy storage Load + Losses + 1,865 1,918 Total Qualifying Capacity 2,108 2,108 Pumps Slide 5 ISO Public

Pease Sub-Area: Requirements Year 2021 LCR (MW) Year Category Limiting Facility Contingency (Deficiency) Overload Table Mountain 60 kV Palermo 115 kV Table Mountain – Pease Palermo – Pease 115 kV and 2021 P6, P7 83 Pease – Rio Oso 115 kV 60 kV line Pease Pease 115 kV 60 kV X X No requirements due to implementation of East Marysville 115/60 kV 2025 All East Marysville project 115 kV Contingency Marysville 60 kV Table Mountain 60 kV Palermo 115 kV Ease Nicolaus 115 kV Pease Pease 115 kV Rio Oso 60 kV 115 kV Year 2025 East Marysville 115 kV Marysville 60 kV Ease Nicolaus 115 kV Rio Oso ISO Public Slide 6 115 kV

Pease Sub-area: Load Profiles Pease Sub-area will be eliminated due to the East Marysville 115/60 kV transmission project expected to be in service in Dec. 2022 ISO Public Slide 7

Placer Sub-Area: Requirements Placer Higgins Bell Drum Gold Hill – Placer #2 Drum – Higgins Gold Hill – Placer #1 Overload Flint Newcastle Horseshoe XX LCR (MW) Year Category Limiting Facility Contingency (Deficiency) Gold Hill Drum – Higgins 115 Gold Hill – Placer #1 and 2021 P6, P7 93 kV line #2 115 kV lines Contingency Drum – Higgins 115 Gold Hill – Placer #1 and 2025 P6, P7 93 kV line #2 115 kV lines ISO Public Slide 8

Placer Sub-area: Load Profiles ISO Public Slide 9

Drum – Rio Oso Sub-Area: Requirements Palermo 230 kV Drum X 115 kV Colgate Palermo 230 kV Pease LCR (MW) 115 kV Year Category Limiting Facility Contingency 60 kV (Deficiency) E. Marysville Bogue Placer 115 kV 115 kV 115 kV Rio Oso 230/115 kV #2 700 Pease E. Nicolaus Rio Oso 230/115 kV 2021 P6 and Palermo 230/115 kV (60 at peak) 115 kV 115 kV #1 Transformer #2 Transformers (55 NQC) Rio Oso 115 kV X Rio Oso 230 kV No requirement due to Rio Oso 230/115 kV Transformer 2025 All West Upgrade project Sacramento Atlantic 115 kV Brighton 230 kV Gold Hill 230 kV 230 kV Lockeford Lodi 230 kV 230 kV Eight Mile Rd Bellota Overload 230 kV 230 kV Contingency ISO Public Slide 10

Gold Hill - Drum Sub-Area: Requirements LCR (MW) Year Category Limiting Facility Contingency (Deficiency) Gold Hill 230/115 kV #1 Drum – Higgins 115 2021 P6 and Gold Hill 230/115 kV 416 (289) kV #2 Transformers Bus-tie-breaker (P2-4) at Drum – Higgins 115 2025 P2 Gold Hill 115 kV 142 (45) kV substation Higgins Placer Drum Bell Gold Hill – Placer #2 Drum – Higgins Gold Hill – Placer #1 Flint Overload Newcastle Clarksville Horseshoe Placerville Missouri Flat – Gold Hill #1 Eldorado PH Missouri Flat – Gold Hill #2 X Contingency X Shingle Diamond Apple Hill Gold Hill Springs Springs ISO Public Slide 11

Gold Hill - Drum Sub-area: Load Profiles MWh ISO Public Slide 12

South of Rio Oso Sub-Area: Requirements Rio Oso LCR (MW) 230 kV Year Category Limiting Facility Contingency (Deficiency) Atlantic Brighton Gold 230 kV 230 kV Rio Oso – Atlantic Rio Oso – Gold Hill 230 kV Hill 230 2021 P6 665 kV Rio Oso – Brighton 230 kV 230 kV Lockeford 230 kV Lodi 230 kV Rio Oso – Atlantic Rio Oso – Gold Hill 230 kV 2025 P6 223 Rio Oso – Brighton 230 kV 230 kV Eight Mile Rd Bellota 230 kV 230 kV ISO Public Slide 13

South of Palermo Sub-Area: Requirements Caribou 115 kV Table Mountain 230 kV Table Mountain LCR (MW) 60 kV Year Category Limiting Facility Contingency (Deficiency) Palermo 1,587 DCTL of Table Mt. – Rio Oso 230 kV Pease - Rio Oso (169 at peak) 2021 P6, P7 and Colgate-Rio Oso 230 kV 115 kV line (164 NQC) Colgate lines Palermo 230 kV Pease 115 kV 60 kV E. Marysville Bogue 2025 All No requirements due to implementation of South of Palermo project. 115 kV 115 kV Pease E. Nicolaus 115 kV 115 kV X X Rio Oso 115 kV Rio Oso 230 kV Overload Contingency ISO Public Slide 14

South of Table Mountain Sub-Area: Requirements Contingency Overload Caribou 115 kV Table Mountain 230 kV Table Mountain X 60 kV X Palermo Catego LCR (MW) Year Limiting Facility Contingency 230 kV (Deficiency) ry Colgate Palermo 230 kV Pease DCTL of Table Mtn. – 115 kV 60 kV Table Mountain – 2021 P6, P7 Palermo and Table Mtn. 1,821 E. Pease 60 kV Rio Oso 230 kV lines Marysville Bogue 115 kV 115 kV Pease E. Nicolaus DCTL of Table Mtn. – Table Mountain – 115 kV 115 kV 2025 P6, P7 Palermo and Table Mtn. 1,367 Pease 60 kV Rio Oso Rio Oso 230 kV lines 115 kV Rio Oso 230 kV ISO Public Slide 15

Changes from 2020 to 2021 2020 2021 Sub-area Load LCR Load LCR Pease 159 88 155 83 Placer 178 1 93 178 93 734 700 Drum - Rio Oso N/A N/A Not a sub-area 416 Gold Hill - Drum 508 831 665 South of Rio Oso N/A N/A South of Palermo N/A 1,569 N/A 1,587 South of Table Mountain N/A 1,764 N/A 1,821 Total 1,862 2,068 1,865 2,110 Gold Hill – Drum sub-area is added to cover P2 contingencies in the area. N/A=Flow-through area. No defined load pocket. 1 This value is updated from last year studies to make it consistent with other areas that include losses Slide 16 ISO Public

Changes from 2024 to 2025 2024 2025 Sub-area Load LCR Load LCR Pease 157 95 161 0 Placer 176 1 89 179 93 Gold Hill - Drum Not a sub-area 512 142 South of Rio Oso N/A 185 N/A 223 South of Table Mountain N/A 1,304 N/A 1,367 Total 1,863 1,304 1,918 1,412 The East Marysville 115/60 kV project eliminates the LCR in Pease sub-area, however due to addition of Gold Hill – Drum sub-area to cover the P2 contingencies in the area, and the higher load forecast, the overall LCR requirement is higher in 2025 as compared to 2024. N/A=Flow-through area. No defined load pocket. 1 This value is updated from last year studies to make it consistent with other areas that include losses Slide 17 ISO Public

Sierra Area Total LCR Need Existing Generation Capacity Needed (MW) Deficiency (MW) Total MW Need Study Year 2021 1,821 289 2,110 2025 1,367 45 1,412 Slide 18 ISO Public