Meeting Summary - 05/16/2025 LLWG Meeting

▶️1 - Antitrust Admonition

▶️2 - Nominations for Chair/Vice Chair

• Martha Henson from Oncor nominated Bob Wititmeyer from Longhorn Power for the LLWG chair role.
• There were no other nominations for chair, leaving Bob Wititmeyer as the sole nominee.
• For vice chair, a nomination was made for Patrick Gravois from ERCOT.
• No other nominations were made for vice chair, confirming Patrick Gravois as the nominee.
• Discussion acknowledged appreciation and anticipation for confirmation at the TAC.
• Kevin Yung from Priority Power was introduced for a presentation.

▶️3 - Large Load Oscillation Event Part 2 – The Customer’s Perspective and Actions

• Acknowledgment of previous presentation by Patrick Gravois on March 4.
• Discussion on subsynchronous oscillation event observed last year involving a large load managed by Priority Power.
• Efforts made to reprogram relays and capture data to identify oscillations.
• Challenges faced due to the granularity and current rate of the data.
• Collaborative effort with ERCOT and Oncor to diagnose and resolve the issue.
• Identification of harmonic distortion and resonance conditions at the customer site.
• Immediate actions and changes made by the customer to rectify the issue, including consulting experts globally.
• Testing conducted under controlled load addition to identify specific load points triggering oscillations.
• Discovery of a software and firmware anomaly at the customer site contributing to the issue.
• Successful resolution of the problem after software adjustments, allowing maximum load without oscillations.
• Discussion on changes in relays, data gathering, and operator training for better management of future large loads.
• Proposal for direct communication between ERCOT and large load operators for improved coordination.
• Suggestion for higher resolution SCADA data to better detect and address oscillations.
• General agreement on improving protocols and establishing standard operating procedures for large loads.

▶️4 - ERCOT Large Load Loss Study for PGRR122

Large_Load_Loss_Analysis_051625_LLWG.pdf

• Jeff Billo emphasized the importance of studying large load tripping and its impact on system frequency and voltage stability.
• Luis Hinojosa presented a study focused on determining the megawatt level at which system stability is compromised due to large load losses.
• The study utilized a historical case from 03/12/2024 to analyze system frequency, inertia, generation mix, and footroom.
• Footroom is defined as the capacity available to respond to high frequency events, similar to headroom but in the downward direction.
• The investigation used dynamic simulations to determine load loss thresholds, ranging from 1,000 MW to 4,000 MW.
• The study identified 2,600 MW as a threshold limit, with over 60.4 Hz potentially causing operational issues.
• Voltage stability concerns were noted in West Texas, indicating a separate limit of 2,000 MW.
• Further monitoring and coordination with plant operators are recommended to prevent setting limits without proper studies.
• Participants discussed the absence of solar at test time and potential for batteries to help with frequency issues.
• Future projections indicate an increase in battery capacity, potentially altering current load loss thresholds.
• Discussions highlighted the need for a market product to manage battery storage state of charge effectively.
• The important consideration was whether location-based contingencies impact load tripping effects.
• ERCOT is monitoring the issue and is working on internal solutions to manage future potential load losses.
• The study led to proposals for implementing a 2,600 MW limit and monitoring a 2,000 MW limit in West Texas.
• Industry participants highlighted the importance of having rapid solutions due to ongoing infrastructure developments.

▶️5 - Preliminary Load Loss Assessment of Operational LLs in ERCOT

LoadLossPreliminaryAssessment_LLWG-05162025-.pdf

• Yunzhi Cheng shared preliminary results of a study assessing the risk of load loss exceeding 2.6 gigawatts under current conditions.
• The study is not completed; it currently analyzes scenarios with different tripping settings and makes use of scenarios based on summer peak and high renewal minimal cases.
• Different scenarios of load tripping settings were studied, and initial findings identified potential tripping from 1.5 gigawatt to 2.5 gigawatt depending on settings.
• Sensitivity analysis includes adding synchronous condensers to see their impact on system conditions and ride-through capability.
• It was concluded that the ITIC curve might not suffice for the long-term growth of large loads since an increase in large loads could breach the 2.6 gigawatt criteria.
• Future work will investigate different locations and engage with the research committee to understand large load behavior better.
• Questions raised by Sunil Dhakal from Lone Star Transmission regarding the modeling in the study of synchronous condensers approved last year were addressed.
• Clayton Greer raised concerns about defining 'electrically close' areas and its impact under various simulated scenarios.
• Discussion about future system changes, such as adding transmission lines, affecting current study assumptions and load tripping profiles.
• A suggestion was made for additional study of voltage ride-through to improve large load outage concerns.
• Conversation about reconnection timelines for large loads implied the need for better engagement between industry stakeholders.

▶️6 - PGRR122

• System operating limit identified: It's a new type of limit, a frequency stability limit, distinct from typical limits like thermal, voltage, and transient stability limits.
• Importance of system operating limit: Needs to be incorporated into planning as it isn't usually detected in standard studies.
• Implementation in large load interconnection studies: Intention to proceed with PGRR122 with a 2,600 MW limit for these studies.
• Operations analysis: Current studies suggest no immediate operational issues by May 2025, but ongoing analysis is needed to predict future constraints.
• Potential solutions for planning: Transmission upgrades, synchronous condensers, grid-forming technology, voltage ride-through requirements, and possibly introducing a fast frequency response down service.
• Voltage ride-through standards: Discussion on implementing such standards for loads to avoid system limitations.
• Discussion on large load interconnection: No current intention to restrict West Texas to a 2,600 MW limit; decisions will be based on further studies.
• Concerns about existing interconnects: Importance of presenting these issues to higher-level boards due to significant impacts on interconnects.
• Load ride through potential: Considerations for allowing load modifications if systems can mitigate issues.
• Ongoing studies: Need for data-backed decisions, especially regarding reconnections and the potential necessity of statcoms for voltage support.
• Request for data center-specific workgroups: Open workshops planned instead of closed subgroups.
• Load threshold discussions: No definitive conclusions yet; ongoing studies to determine impacts and technological constraints for ride-through capabilities.
• Further discussions and analysis required: To address the system's capability to handle initial disturbances and subsequent reconnections.

▶️7 - Data Center Ride-Through Next Steps

Data-Center-Operations-TF-LFLTF-051625.pdf

• Discussion centered around low voltage ride through issues impacting data centers, identified by three main opportunities for problems: three strikes control, UPS system switching configurations, and variable frequency drive motors.
• The problem with UPS inverter operations is discussed, particularly their disconnecting from the grid during perceived system problems, causing delays.
• A vendor solution was mentioned which might involve modifying the operations of UPS systems to draw additional power from the grid while an inverter is supplied to avoid disconnection.
• There is a need to move forward with solutions, considering the existing approved connections over four gigawatts and developing requirements for load commissioning by ERCOT.
• The importance of reprogramming UPS systems for immediate return with line voltage recovery was discussed.
• Questions were raised about the capacity and feasibility of running low voltage tests at data centers.
• The importance of ensuring solutions that do not risk blackouts in case of large failures or grid issues was emphasized.
• The need to understand the timing and flow of events during grid failures was noted, bringing up the idea of analyzing events on a cycle by cycle basis.
• A proposal for a double conversion medium voltage UPS BESS solution was made, involving a grid following and forming component.
• Discussion on enabling the connection of large loads as guaranteed reliability loads to expedite their integration utilizing flexibility agreements to mitigate risks associated with disconnecting from the grid during outages.
• Clarification was sought on manual versus automated handling of switches and the operational feasibility of implementing an automated system.
• Potential market disruptions and operational complexities were acknowledged, with a focus on managing these flexibly and clarifying the terms for load management.
• Potential need for ERCOT to develop further market mechanisms to support these integrations was mentioned.

▶️8 - Large Load Survey Form

ERCOT-Dynamics-Working-Group-Large-Load-Data-Survey_p9_20250515_DWG_Updated.pdf

• The form was developed by a subgroup of Subject Matter Experts (SMEs) from various DSPs in conjunction with ERCOT.
• The primary purpose is to assist DSPs and customers in gathering consistent information for large load interconnection processes.
• The form includes sections on facility design, basic load information, technical characteristics, equipment specifics, dynamic models, backup systems, and protection settings.
• Concerns were raised about the clarity of the form and whether it should change title to better reflect its audience, suggesting it's intended for TSPs rather than end customers.
• Floyd Trefny expressed concerns about sending the form directly to customers as they may not understand the technical details.
• Sun Wook from ERCOT explained that the form should serve as a standardized communication tool between TSPs and customers.
• Blake King raised issues about the confidentiality of information submitted by non-market participants, suggesting the need for further discussion on the protection of proprietary data.
• There was a discussion about when the form should be filled during the interconnection process, particularly about its role in the scoping meeting and stability studies.
• Evan Neel raised concerns about data availability during the early stages of load projects, emphasizing that stability studies might have to be updated if there are changes in the project.
• A suggestion was made to consider a staggered approach similar to the generation interconnection process, allowing for data collection in stages as the project develops.
• Patrick Gravois responded that the process aims to use the best available information for stability analyses.
• Concluded with an acknowledgment of the need for a balance between information gathering and project development.

▶️9 - Data Center Ride-Through Information Request

• ERCOT operations are seeking information on ride-through performance, backup generation, and UPS systems from existing loads.
• A market notice is being developed in collaboration with TSPs to evaluate data centers under development with a focus on ride-through capabilities.
• There is a need for more detailed information which will be gathered using a large load survey with additional questions regarding protection settings and backup generation.
• A new market notice will be issued for TSPs to gather data on large loads, both operational and planned, to integrate this information into future studies.
• Information gathered will guide a potential commissioning test process which is still undefined, and ensure accuracy in load model verification.
• Verification and testing of ride-through capabilities are essential, particularly due to potential issues identified in West Texas and the Panhandle.
• There is a need to set testing criteria to validate the information against expected performance outcomes during the commissioning process.
• A manual process may be needed to ensure load models are accurate, particularly for loads nearing operational status.
• Appreciation was expressed for the form to be used in the process which provides clarity on requirements before grid connection.

▶️10 - Splight NPRR - 12:00 p.m.

Splight-LLWG-Presentation-5.16.25.pdf

• Introduction by Helen Kemp from Splight, a technology company, discussing advanced transmission technology and its operations across North America, South America, and Europe.
• Presentation of draft PRR language to introduce the concept of Fast Responding Loads (FRL) that can quickly respond to grid emergencies, enhancing reliability and capacity allocation.
• Discussion of the integration with Guaranteed Reliability Load (GRL) and the potential for merging or treating it as a subcategory.
• Introduction to Splight’s technology as a mechanism for implementing the proposed NPRR, focusing on automatically responsive large loads.
• Bob King from Splight explained a real-world example involving a data center with energy management systems and the application of battery storage to ensure responsiveness.
• Emphasis on Splight’s ongoing operations in other regions and the capability of their system for real-time control and machine-to-machine communication.
• Splight’s proposal allows more full utilization of transmission line capacities, suggesting a pathway for existing data centers to grow.
• Feedback and questions from ERCOT members Freddy Garcia and Floyd Trefny regarding the proposal, addressing concerns related to data management and RAS (Remedial Action Scheme) classification.
• Acknowledgement of regulatory concerns about data access from transmission service providers (TSPs) and the need for offline discussions.
• Encouragement for further conversations with NERC about regulatory compliance and defining characteristics of the load.
• Final comments from ERCOT members about concerns and the potential positive impact on jobs and load management in Texas.

▶️11 - Battery/Data Center Use Case

11-Megapack-at-Data-Centers-_-ERCOT-LLWG_5.16.25_vShare.pdf

• Tesla presented on battery storage applications at data centers to provide technical solutions, focusing on load smoothing and low voltage ride-through support.
• The presentation was not intended as a sales pitch or policy recommendation, but focused on technical aspects.
• Tesla's battery units, called 'megapacks', offer two megawatts and four megawatt-hour capacity, scalable to approximately 200 megawatt and 400 megawatt-hour per acre.
• Key battery storage use cases include load smoothing for AI training with oscillation challenges, low voltage ride-through support, load shaping for flexible utility connection, and backup power.
• AI data centers face challenges with highly variable power consumption, leading to sub-second shifts and power demand fluctuations of up to 90%.
• Using Tesla's battery product can smooth out these fluctuations, reducing power load variability by more than 70%, without significantly impacting battery lifespan; Tesla offers a 15 to 20-year warranty.
• Real-world examples show significant improvements in power load stabilization, frequency regulation, and mechanical protection for on-site generators using the megapack system.
• Questions addressed included battery sizing related to peak data center power draw, inverter size for the load, and how long batteries can maintain optimal usage.
• A challenge discussed was low voltage ride-through which can be mitigated by using a megapack system to maintain consistent load during grid faults.
• Batteries can offer flexible load shaping for easier system integration, allowing data centers to connect faster and manage periods of overload.
• Examples of programs enabling faster interconnections include PG&E's FlexConnect, showing that battery use can potentially accommodate significant new load capacity.
• Batteries are also compared to diesel generators for backup power, with equivalency around 6 to 8 hours duration at similar cost but with considerations for business decisions regarding duration needs.
• Tesla presented use cases of existing megapack installations at sites including their Austin Gigafactory and xAI's Colossus data center.
• ERCOT expressed interest in the concept and potential of batteries for voltages ride-through issues, with some discussion on the scalability and regulatory perspective of co-locating battery systems with large loads.