2017-2018 TRANSMISSION PLAN March 14, 2018 REVISED DRAFT Foreword to Revised Draft 2017-2018 Transmission Plan This revised draft transmission plan reflects a number of changes from the draft plan released on February 1, 2018. To assist our stakeholders following the transmission plan cycle, we have summarized a number of those changes, with particular emphasis on a number of projects where the recommendations have progressed since the release on February 1 and the subsequent stakeholder meeting on February 8: • The model estimating the impact of the transmission plan on the ISO’s High Voltage TAC has been updated and the results added to the model. • The Oakland Clean Energy Initiative project is recommended for approval • The Phasor Measurement Unit project has been added and is recommended for approval • The Bridgerville-Garberville #2 115 kV line project is recommended to remain on hold. • The Kearney-Caruthers 70 kV Line Reonductor project is recommended to proceed with the original scope. • The recommended revised scope for the Kern 115 kV Area Reinfoement has been updated as presented at the February 8 stakeholder meeting. • Section 2.10 addressing the need for phasor measurement units to be installed on all ISO balancing authority area interties has been added. • Several projects approved in the 2016-2017 transmission planning cycle have been added to Table 7.1-1: Status of Previously-approved Projects Costing Less than $50M, that had been omitted from the table in the Draft 2017-2018 Transmission Plan. • The in-service date for a number of previously approved projects have been updated. A number of clarifications and edits have also been added throughout the plan to address other stakeholder comments. 2017-2018 ISO Transmission Plan March 14, 2018 Table of Contents Executive Summary ..................................................................................................... 1 The Transmission Planning Process ................................................................ 3 Planning Assumptions and State Agency Coordination .................................... 4 Key Reliability Study Findings .......................................................................... 5 Renewables Portfolio Standard Policy-driven Transmission Assessment ......... 7 Key Economic Study Findings .......................................................................... 8 Non-Transmission Alternatives and Preferred Resources............................... 10 Informational Studies ...................................................................................... 10 Conclusions and Recommendations .............................................................. 11 Chapter 1 ................................................................................................................... 13 1 Overview of the Transmission Planning Process ............................................ 13 1.1 Purpose ........................................................................................ 13 1.2 Impacts of the Industry Transformation ......................................... 16 1.2.1 Load Forecasting and Distributed Energy Resources Growth Scenarios .................................................................... 17 1.2.2 Resource Planning .................................................................. 19 1.2.3 System Modeling, Performance, and Assessments ................. 29 1.3 Structure of the Transmission Planning Process ........................... 31 1.3.1 Phase 1 ................................................................................... 31 1.3.2 Phase 2 ................................................................................... 33 1.3.3 Phase 3 ................................................................................... 35 1.4 Interregional Transmission Coordination per FERC Order No. 1000 ............................................................................. 37 1.5 ISO Processes coordinated with the Transmission Plan ................ 39 Chapter 2 ................................................................................................................... 43 2 Reliability Assessment – Study Assumptions, Methodology and Results ........ 43 2.1 Overview of the ISO Reliability Assessment .................................. 43 2.1.1 Backbone (500 kV and selected 230 kV) System Assessment ............................................................................. 43 2.1.3 Regional Area Assessments .................................................... 44 2.1.4 Peak Demand ......................................................................... 44 2.2 Reliability Standards Compliance Criteria...................................... 45 2.2.1 NERC Reliability Standards ..................................................... 45 2.2.2 WECC Regional Criteria .......................................................... 45 2.2.3 California ISO Planning Standards .......................................... 45 California ISO/MID i 2017-2018 ISO Transmission Plan March 14, 2018 2.3 Study Assumptions and Methodology ........................................... 46 2.3.1 Study Horizon and Years ......................................................... 46 2.3.2 Transmission Assumptions ...................................................... 46 2.3.3 Load Forecast Assumptions .................................................... 47 2.3.4 Generation Assumptions ......................................................... 50 2.3.5 Preferred Resources ............................................................... 58 2.3.6 Firm Transfers ......................................................................... 64 2.3.7 Operating Procedures ............................................................. 65 2.3.8 Study Scenarios ...................................................................... 65 2.3.9 Contingencies ......................................................................... 70 2.3.10 Study Methodology .................................................................. 72 2.4 PG&E Bulk Transmission System Assessment ............................. 75 2.4.1. PG&E Bulk Transmission System Description ......................... 75 2.4.2. Study Assumptions and System Conditions .......................................... 76 2.4.3. Assessment and Recommendations ....................................... 81 2.5 PG&E Local Areas ........................................................................ 90 2.5.1 Humboldt Area ........................................................................ 90 2.5.2 North Coast and North Bay Areas ........................................... 95 2.5.3 North Valley Area .................................................................. 105 2.5.4 Central Valley Area ............................................................... 111 2.5.5 Greater Bay Area .................................................................. 121 2.5.6 Greater Fresno Area ............................................................. 133 2.5.7 Kern Area .............................................................................. 146 2.5.8 Central Coast and Los Padres Areas .................................... 153 2.5.9 California High Speed Train Project Load Interconnection ..... 162 2.6 Southern California Bulk Transmission System Assessment ....... 167 2.6.1 Area Description .................................................................... 167 2.6.2 Area-Specific Assumptions and System Conditions .............. 169 2.6.3 Assessment Summary ........................................................... 171 2.6.4 Request Window Project Submissions .................................. 172 2.6.5 Consideration of Preferred Resources and Energy Storage .. 172 2.6.6 Recommendation .................................................................. 172 2.7 SCE Local Areas Assessment ..................................................... 173 2.7.1 SCE Tehachapi and Big Creek Area ..................................... 173 2.7.2 North of Lugo Area ................................................................ 177 2.7.3 SCE East of Lugo Area ......................................................... 181 2.7.4 SCE Eastern Area ................................................................. 184 2.7.5 SCE Metro Area .................................................................... 188 2.8 Valley Electric Association Area .................................................. 197 2.8.1 Area Description .................................................................... 197 2.8.2 Area-Specific Assumptions and System Conditions .............. 197 2.8.3 Assessment Summary ........................................................... 199 2.8.4 Request Window Project Submissions .................................. 199 2.8.5 Consideration of Preferred Resources and Energy Storage .. 200 2.8.6 Recommendation .................................................................. 200 2.9 SDG&E Area ............................................................................... 201 2.9.1 San Diego Local Area Description ......................................... 201 2.9.2 Area-Specific Assumptions and System Conditions .............. 201 California ISO/MID ii 2017-2018 ISO Transmission Plan March 14, 2018 2.9.3 Assessment Summary ........................................................... 204 2.9.4 Request Window Project Submissions .................................. 204 2.9.5 Operational Modification and RAS Mitigations ......................