Meeting Summary – 10/11/2024 IBRWG Meeting
Published: October 11, 2024
1 – Antitrust Admonition – Julia Matevosyan
Antitrust admonition was shared with meeting participants.
2 – SSR/SSFR Best Practices – Anuradha Dissanayaka, Andrew Isaacs – Electranix
Introduction of Anuradha Dissanayaka, Electranix engineer leading SSO studies. Overview of Sub-Synchronous Oscillations (SSO) including historical events and impacts: Mojave generator SSR event in the 1970s and south Texas SSCI event in 2009. Importance of detailed studies for IBR plants near series capacitors before commissioning to prevent issues. Explanation of various sub-synchronous phenomena: SSR, SSTI, SSCI, SSFR. Description of study processes: Screening (passive and dynamic frequency scanning) and detailed EMT simulations. Challenge of modeling accurate systems and the back-and-forth required with OEMs to complete studies. Importance of accurately modeling transformer saturation to prevent SSFR (Sub-Synchronous Ferro Resonance). Discussion on the problems of adding new series capacitors in areas with high IBR penetration. Sensitivity studies and control tuning as solutions for various sub-synchronous issues. Potential of grid-forming battery energy storage systems (BESS) to improve damping and minimize risks. Application of SSR and SSFR detection relays to manage certain phenomena. Recent findings about grid-forming BESS providing positive damping over a wide frequency range.
3 – PFR from IBRs under “Deep” Curtailment – Scott Karpiel – SMA, All
PV_Inverter_OEM_PFR_Capability_Under_Curtailment_20241011.pdf
Discussion on the ability of inverter-based resources (IBR) to provide primary frequency response (PFR) under deep curtailment. SMA inverters can respond in less than 150 milliseconds, but are limited by the accuracy of measurement devices and plant controller processing time. Photovoltaic (PV) resources operate at maximum power points and may not increase AC power to respond to frequency events if curtailed to zero. IBR units are not ideal for frequency response compared to hybrid systems with battery energy storage systems (BESS). A question was raised about SMA inverters’ ability to respond when curtailed to zero with adequate irradiance. Scott emphasized the role of the plant controller in ensuring the inverter can increase active power quickly during low-frequency events. Discussion on the use of weather stations and algorithms to estimate the available power for frequency response, acknowledging it as challenging. Questions regarding the accuracy, model performance under low dispatch, and potential discrepancies in model behavior were addressed. The discussion included how curtailment affects the high sustained limit (HSL) reported to ERCOT and the estimation of available capacity. Clarification that plant controllers can perform ongoing measurements crucial for frequency response, with the role of the PPC in providing grid frequency data.
4 – NOGRR245 and NOGRR255 Updates – Stephen Solis – ERCOT
NOGRR245_255_Update_IBRWG_10112024.pdf
NOGRR245 was recently approved, effective October 1, 2024; changes to guides and language in process details provided. Performance requirements from NOGRR245 become effective after entities enhance ride-through capabilities; coordination activities are ongoing. Model quality testing procedures updated in DWG procedure manual, approved by Reliability and Operations subcommittee. NOGRR245 includes specific steps for handling performance failures, such as investigation, reporting, and model validation. NOGRR255, effective August 1, 2024, aligns with PRC-028, focusing on disturbance monitoring equipment and data retention requirements. NOGRR255 introduces timelines for resource compliance and site selection for monitoring equipment installations. FAQs on NOGRR255 clarified language issues and requirements for disturbance monitoring at plant level versus individual inverters or turbines. Discussion on monitoring equipment emphasized root cause analysis importance and advisory on utilizing existing equipment. Future updates to NOGRR255 depend on outcomes from FERC directions and ongoing performance assessments.
5 – NERC Standards Update – PRC-029 – TRE
Rachel Coyne presented updates in place of Mark Henry. Activity around PRC-029 related to milestone two for FERC Order 901 was discussed. PRC-029 caused industry disagreements; NERC invoked rules of procedure, section 321. A technical conference was held in September to build consensus with OEM participation. Changes to PRC-029 include updating the ride-through definition and modifying requirements three and four. PRC-029 passed with 77.88% support; other standards in milestone two also passed. Standards to be filed with FERC by November 4. Update on regional standard bow one TRE version two project SAR-013 was given. Scope of SAR includes provisions on governor generator deadband, rules of GOBA and CEA roles, and PFR performance for battery energy storage. Project approved by Texas RE MRC on September 18, and standard drafting team solicitations concluded. Next step is for MRC to approve slate and start drafting the next revision of that standard Consensus reached, particularly on requirement three concerning the broad band of frequency operational range. Continued discussions on PFR response limitations, especially for IBR, beyond OEM capabilities.
6 – Other Industry Updates – Julia Matevosyan ESIG
ERCOT_IBRWG_NERC_and_Other_Updates_101024.pdf
Series of grid forming seminars will include six sessions with various presenters from ISOs, utilities, NERC. Registration for the seminars will be available on the IBR working group’s presentation. The I2X meeting is scheduled for October 24 in Providence and will be a hybrid meeting. The meeting is sponsored by the Department of Energy and involves the I2X Interconnection Innovation Change. The I2X meeting will be combined with a workshop with numerous presentations over two days. Registration will be available online for the seminar series and the webinar in mid-October on grid funding projects.
6.1 – Lunch Break
- 30-minute lunch break.
7 – AGS ESR Model Quality Tests and Discussion – Poria Astero, Sun Wook Kang – ERCOT
ERCOT AGS-ESR Oct-11-2024 IBRWG
Discussed ERCOT recommendations on advanced grid support inverter-based energy storage resource (AGS ESR) test requirements. Sun Wook Kang emphasized the importance of the effort due to the increasing presence of inverter-based resources (IBRs) and decreased availability of conventional units for maintaining grid reliability. Highlighted key efforts like synchronous condenser projects, PGRR109 improvement, and NOGRR245 approval for better IBR operating requirements. Electranix contracted in 2023 to support the development of functional specifications and test framework for AGS ESR. Presentation of interconnection requests showed a 93% IBR and 42% battery projects focus as of August 2024. Battery resources are seen as increasingly important for ERCOT and are capable of software updates for grid support (GFM capability). Expectation that AGS ESR will improve grid stability and system strengths, while reducing impact of disturbances. Plans to submit PGRR and NOGRR by year-end, involving stakeholder feedback on test requirements. Poria Astero outlined detailed AGS ESR test framework including site-specific model quality and unit model validation tests. Test Bench setups explained: Test Bench 1 with impedance to model grid stress, Test Bench 2 for islanded operation. Several test scenarios discussed involving stability under phase angle jumps, voltage disturbances, and frequency changes. Presentation emphasized reactive power following voltage changes, inertial response during frequency changes, and system SRF AGS ESR test requirements considered grid-following and grid-forming characteristics. Existing large voltage disturbance test and a modified loss of synchronous machine test to ensure parallel operation capability. Acknowledged further test suggestions from Electranix, with a focus on necessary tests for AGS ESR adoption. Focus on ongoing collaboration with stakeholders, manufacturers for test validation and feedback.
8 – Other Business
Not Discussed
Get this full Meeting Summary with Clips, transcript and much more
Start your free trial todayAll Blog Posts
- 12/10/2025 Member Representatives Committee Meeting Summary
- 12/10/2025 PRS Meeting Summary
- 12/10/2025 Texas RE Audit, Governance, Risk, & Finance Committee Meeting Summary
- 12/10/2025 Texas RE Board of Directors Meeting Summary
- 12/09/2025 TDTMS Meeting Summary
- Meeting Summary – 09/23/24 CMWG Meeting
- Meeting Summary – 09/19/24 TAC Meeting
- 09/19/2025 ERCOT LLWG Meeting Summary
- Meeting Summary – 09/16/24 IBRWG Meeting
- Meeting Summary – 10/11/2024 IBRWG Meeting
- Meeting Summary – 10/10/2024 Board of Directors Meeting
- Meeting Summary – 10/05/24 PUCT Workshop
- Meeting Summary – 09/24/24 PLWG Meeting
- State Affairs
- Meeting Summary – 10/09/24 Reliability & Markets Committee Meeting
- Meeting Summary – 09/24/24 WMWG Meeting
- 09/13/2024 RTCBTF Meeting Summary
- Meeting Summary - NOGRR245 - 08/08/24 Review of Current Status
- Meeting Summary - 12/03/24 Joint Legislative Oversight Committee On Grid Reliability