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November 8, 2024
Meeting Summary - 10/11/2024 IBRWG Meeting
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
- Meeting paused for a 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
Related controls: NOGRR245 – NOGRR255 – PGRR109