Meeting Summary - 05/20/2025 RPG Meeting

▶️1 - Antitrust Admonition - 9:30 a.m.

▶️2 - Miscellaneous Updates

• No updates were presented during this agenda item.
• No participants raised their hands or made comments in the queue.

▶️3 - EIR Status Update – Baytown Area Load Addition Project

EIR-CNP-Baytown_Area_Load_Addition_Project_May_RPG.pdf

• Ben Richardson from ERCOT presented the status update on the CenterPoint Baytown area load addition project.
• The project is a $141 million, tier one project due to a 500 MVA load addition in the Baytown area.
• Previous meetings addressed the project scope, and the current meeting focused on additional findings.
• Options 2 and 2A involve addressing overloads discovered in initial assessments and maintenance evaluations.
• Option 3 considers bringing in 345-kV lines from Sheldon to Baytown for substation benefits.
• A finalized recommendation is aimed for Q2 2025, following the completion of option two a.
• Discussion on load scaling was raised regarding the inclusion of new flexible loads and how historical data is used.
• The necessity of studying load clusters versus individual loads was addressed, with project submissions often determining clustering.
• Procedures were discussed on the financial responsibilities of load customers, including securitization versus rate basing of upgrades.

4 - EIR Status Update – Texas A&M University System RELLIS Campus Reliability Project

• Not Discussed

▶️5 - EIR Status Update – Roscoe Area Upgrades Project

EIR-Oncor-Roscoe-Area-Upgrades-Project-StatusUpdate-May_2025_RPG.pdf

• Presenter: Abishek Penti provided a status update on the Oncor Roscoe area upgrades project.
• Project Overview: Oncor submitted the Roscoe area upgrades for RPG review in December 2024, a tier two project with an estimated cost of around $83 million, requiring a CCN with an expected service date of June 2028.
• Project Purpose: Address voltage violations as identified by Oncor.
• Project Scope: Involves construction and upgrade activities, including a new Oak Spring station, auto transformers, line upgrades, and decommissioning and rebuilding of certain lines.
• Study Overview: Used 2024 RTP data and updated loads for the study base case.
• Preliminary Results: ERCOT identified voltage violations and power flow violations and assessed four different options, deeming options one and four for further evaluation.
• Maintenance Outage Evaluation: Shortlisted options did not show voltage, thermal, or power flow violations.
• Load Serving Capability: Both options improved operational flexibility with option four slightly better.
• Cost Estimates: Option one estimated at $84.3 million and option four at $133.4 million, both requiring CCN.
• Preferred Option: Option one selected due to addressing project needs, meeting reliability criteria, being cost-effective, and improving long-term load capacity.
• Congestion Analysis: No new congestion identified within the study area for the preferred option.
• Next Steps: EIR report to be posted in the MIS by May.
• Q&A: Discussed assumptions regarding flexible loads and transfer capability.

▶️6 - Muscovy and Voss Lake 345/138-kV Project Overview

Oncor_Muscovy_Voss-Lake_RPG_05202025.pdf

• Overview of the Muscovy and Voss Lake 345/138-kV project presented.
• Joint project with Oncor and LCRA TSC.
• Tier one project located in Williamson and Milam Counties.
• Project aims to resolve thermal violations, provide additional 345-kV sources, further network transmission facilities, and enhance system reliability.
• Total combined cost for Oncor and LCRA TSC is just under $382,000,000.
• Project includes installation of three new 345/138-kV autotransformers, one 10.4 Mvar capacitor bank, and new transmission lines.
• 29 miles of new 345-kV double circuit transmission lines and 2 miles of new 345-kV transmission lines to be installed.
• Highlight of existing configuration reveals thermal violations mainly at Hutto and Sandow switches due to significant load growth.
• Oncor to establish a new Muscovy 345/138-kV switch east of Limmer and Teal Switch, with breaker and a half arrangement.
• Construction of Voss Lake 345/138-kV switch north of Sandow with one auto transformer.
• Construct 25-mile 345-kV double circuit line from Muscovy to Voss Lake rated 5,000 amps.
• Construct 2-mile 345-kV line from Voss Lake to Walleye Creek as a single circuit on double circuit capable structures.
• Coordinate construction of a 4-mile 345-kV double circuit line from Limmer to Muscovy rated 5,000 amps.
• No questions were raised after the presentation.

▶️7 - ERCOT Independent Review Scope: Muscovy and Voss Lake 345/138-kV Project

EIR-Oncor-and-LCRA-TSC-Muscovy-Voss-_SCOPE_May2025_RPG.pdf

• Presenter Abishek Penti gave an overview of the project's scope for Oncor and LCRA TSC's Muscovy and Voss Lake 345/138-kV project.
• Project classified as tier one with an estimated cost of $381,830,000 and an estimated in-service date of December 2028.
• The project's main purpose is to address reliability violations identified by Oncor and LCRA.
• Independent review is underway with the use of 2024 RTP 2029 summer peak case as a seed for the study base case.
• Consideration of transmission projects with in-service dates on or before December 1, 2028. Other placeholder projects from RTP 2024 will be removed.
• Evaluation criteria include thermal ratings, voltage limits, and contingencies P0 to P6 and G-1 and X-1 evaluations on specified generators and autotransformers.
• Study procedure involves need analysis, project alternatives testing, planned maintenance outage, and long-term load serving capability assessments.
• Congestion analysis and potential sensitivity analyses might be performed as per relevant sections of the planning guide.
• Final recommendations are expected by the end of Q3 2025.
• Discussion addressed questions on potential inclusion of 765-kV import lines in independent reviews; deemed unlikely due to timelines.

▶️8 - 2026 Long-Term System Assessment (LTSA) Planning

2026_LTSA_20250520.pdf

Presenter: Pengwei Du from ERCOT

• Evaluating potential needs of ERCOT's high voltage system (345-kv and 765-kv) for 10-15 years out.
• Strategic guidance for the six-year planning process.
• Utilization of multiple scenarios to explore future outcomes based on different sensitivities and key factors.

Key Planning Aspects

• Stakeholder engagement process initiated for feedback on key assumptions and scenarios.
• Current trend scenario as a baseline, with additional scenarios to represent different load growth trajectories.
• Biannual process with report completion expected by December 31, 2026.

Key Assumptions

• Adjusted load forecast reflecting adjustments applied to TSP provider larger load addition.
• Moderate growth assumptions for rooftop PV and electric vehicles (EV).
• Carbon price assumed at $0 per ton with no EPA rules impact for coal and gas units.
• Economic retirement is considered instead of fixed age retirement.

Large Flexible Load (LFL) Assumptions

• 60% of LFL has a strike price at $100/MWh.
• 30% of LFL responds at $200/MWh.
• 10% of LFL has a strike price at $1,000/MWh.

Capacity Expansion Analysis

• Built upon starting generation portfolio including existing and planned resources that meet Planning Guide Section 6.9(1) requirements.
• Determination of additions of new resources and economic retirement of existing generation fleet.

Questions and Discussions

John Snyder: Study years for LTSA include ten and fifteen years out, focusing on transmission needs for years 2036 and 2041.

Prabhu Gnanam: Transmission modeling based on RTP findings; base cases include approved projects by the commission.

Xuan Wu: Transverse stability will not be studied in LTSA but will be examined in annual planning assessments.

Shuye Teng:

• Regarding Generation Retirement: Fixed age retirement removed due to inconsistencies; open to discussing adjustments.
• Regarding Large Flexible Load: Assumptions based on actual responses and 2010 feedback from large load owners.
• Environmental Policy Assumptions: Scenarios in the past may vary; intention to capture policy variations in future scenarios.

▶️9 - Weather Year Selection Methodology Updates for 2025 Regional Transmission Plan (RTP) Economic Study

Weather_Year_Selection_Update_Final.pdf

• Nelson Avila presented updates to the weather year selection methodology for the 2025 RTP economic study.
• The weather year selection is crucial as it determines renewable and load profiles for production cost simulation.
• Prior to 2017, ERCOT used a single weather year representing the average of 16 available years.
• In 2017, ERCOT developed a methodology to include sensitivity weather years to address weather uncertainties.
• The updated methodology now incorporates peak net load and net load demand variables, improving risk capture during peak net load hours.
• New metrics now include correlation with location of wind and solar units.
• Weather years are now ranked with different scores separating load and renewables compared to the previous single-scoring method.
• Flexibility is introduced to select weather years specific to constraints related to renewable generation patterns.
• Stakeholder feedback is sought on the new methodology.
• Variables used in the new methodology include peak load, demand load, peak net load, and demand of net load.
• Renewable generation variables include correlated metrics for wind and solar capacity factors.
• A final score is created by averaging renewable and load scores, helping to rank weather years on a heat map.
• A difference with the previous methodology is the ranking order of load variables (descending) versus renewable variables (ascending).
• Sensitivity weather years are selected to focus on known constraints like Panhandle and West Texas exports.
• Question and answer session included queries about distinctions between peak and net load, the methodology's applicability to reliability studies, and adjustments based on DER growth.
• ERCOT confirms the 2025 RTP methodology targets economic rather than reliability studies.
• Discussion continues on the application of the new methodology to other constraints and potential timeline for implementation.
• ERCOT emphasizes that stakeholder feedback will be considered before finalizing the methodology.

▶️10 - Adjourn