Meeting Summary – 08/09/24 IBRWG Meeting

0 – Antitrust Admonition – Julia Matevosyan.

1 – Last Update Request – Fred Huang

• Two presentations were given last month on advanced grid support and grid forming capability.
• Presentations covered functional specification and test framework, and an assessment of potential impacts of reforming batteries on ERCOT grid stability and reliability.
• Fred mentioned they are working on a draft revision request and plan to post it at least a week before the September IBRWG meeting.
• The draft will be included on the agenda for the September meeting for review and discussion

2 – SPWG/IBRWG Coordination, Auto-reclosing close to IBR plants – Mark McChesney – Oncor, SPWG chair

• Action item from March ROS meeting: Develop guidance for adjusting transmission reclosing and sectionalizing schemes to improve IBR ride-through probability.
• Discussion on current practices: Oncor’s reclosing philosophy referenced IEEE standard c37.14.
• Typical scenario: Faults on tie line lead to a 20-second open interval before reclosing.
• Faults on adjacent lines: Typical 10-second open interval for remote terminal reclosing.
• Oncor’s sync check settings: Voltage > 75% of nominal, angle difference < 40 degrees, maximum slip frequency of 0.067 Hz.
• Open discussion solicited for feedback and concerns from IBRWG.
• Stephen Solis commented on the potential need to change reclosing parameters, considering IEEE 2800 requirements.
• Diverse reclose schemes among TSPs: From no reclose to multiple attempts within a ten-second period.
• Aim: Coordinate TSP’s reclose schemes with IBRs to avoid unnecessary trips, considering IEEE 2800 requirements.
• Oncor’s approach: Longer open intervals and limited recloses around generating units.
• Clarification on terminology: ‘Open interval’ as the time delay before a reclose attempt.
• Discussion on the overall goal: Ensuring TSP reclose strategies don’t trip IBRs.
• Consideration of IEEE 2800 table relevant to multiple excursions.
• Site-specific evaluation recommended for reclose schemes around IBR plants.
• Need to capture coordination guidelines between TSPs and IBRs in documentation.
• Potential requirement to discuss further and possibly introduce a rule change.
• Differences in reclose scheme considerations for wind turbines compared to solar PV or batteries.
• Importance of capturing and sharing the range of reclose schemes used by TSPs.
• Plan to summarize and poll SPWG group on typical schemes and considerations.
• Future coordination to discuss data and feedback in IBRWG meetings.

3 – ERCOT RFI to Support Single Model ESR – ERCOT, All

• Julia Matevosyan clarified a past miscommunication about single model representation of ESR within ERCOT systems. Will happen together with real time co optimization implementation.
• Joel Koepke, ERCOT’s grid coordination manager, provided an overview of the Request for Information (RFI).
• The RFI, initiated on August 6, targets resource entities of commissioned or near-commissioned ESRs.
• Purpose of the RFI is to collect information to avoid validation issues during future submissions in the RIOO application.
• Resources receiving the RFI include those commissioned, in commissioning process, or with approved production load date.
• RTC+B aims to transition from a combo model representation to a single model representation of ESRs by Q4 2025.
• RIOO will be the first application to make the transition, with downstream systems changing later.
• The new single model representation will streamline the submission process, reducing errors and consolidating the load and generation aspects of ESRs.
• Resource entities will receive an ERCOT-created ESR name to facilitate telemetry and testing for RTC to go live in Q4 2025.
• Details of information requested in the RFI include substation details, ESR configuration, and reactive capability during charging.
• Joel highlighted the setup for telemetry and system testing ahead of the RTC go-live date.
• There will be updates to the RIOO application and subsequent changes will depend on the resource stage in the submission process.
• Questions from participants addressed specifics about handling in-flight applications and interconnection procedures.

4 – NERC Standards Update PRC-029, PRC-028, PRC-30 – Julia Matevosyan – ESIG

• Julia presented updates on NERC standards PRC-029, PRC-028, PRC-030.
• Emphasized that her interpretation should be cross-checked with original documents.
• FERC Order 901 directed NERC to update or create new standards for inverter-based resources (IBRs).
• Standards PRC-028, PRC-029, and PRC-030 are up for balloting by August 12.
• PRC-028 focuses on disturbance monitoring and reporting for IBRs.
• PRC-029 outlines frequency and voltage ride-through requirements for IBRs.
• PRC-030 covers unexpected inverter-based event mitigation.
• Stressed the importance of these standards with IBRWG scope and focus. Relating PRC-029 to NOGRR245 and PRC-028 to NOGRR255
• There is a low approval rate for the current drafts; 66% approval needed.
• Requested participation in the balloting process as this is NERC’s last opportunity to ballot project with traditional mechanism.
• If not passed NERC will take requisite action during August Board of Trustees meeting to ensure requirements are completed and filed with FERC by 11/4/2024
• Implementation of PRC-029 includes applicability to IBRs of 20 MVA capacity connected to systems  greater or equal to 60 kV.
• Mentioned differences between PRC-029 and IEEE 2800 standards, notably that frequency ride-through requirements are wider in PCR-029.
• PRC-029 includes specific volts per hertz capability requirements.
• PRC-029 will be effective 12 months after NERC Board of Trustees adopts it; compliance for smaller IBRs by January 1, 2027.
• PRC-028 compliance is necessary for PRC-029 operations monitoring.
• Discussed PRC-029 exemptions for hardware limitations in meeting voltage ride-through requirements
• Frequency ride-through, RoCoF, phase jump, and volts per hertz requirements apply universally.
• Addressed questions regarding OEM involvement, limitations of type 3 wind turbines, and voltage ride-through criteria.
• Mark Henry of TRE clarified that for NERC standards, ECORT is FERC jurisdictional
• Voting on IBR definition glossary item by August 13.

5 – NOGRR245 Update – Stephen Solis – ERCOT

• A detailed presentation by Andy Gallo from ERCOT is available on the meeting page.
• Additional work has been done between ERCOT and joint commenters.
• Comments from this work are expected to be posted by next Monday.
• The R&M committee will review on the 19th and the board on the 20th.
• Stephen addressed a question regarding how MQT changes tie into NOGRR245.
• Further discussion on MQT changes will occur later in the meeting.

6 – RoCoF and Phase Jump Measurement Discussion – Stephen Solis – ERCOT, All

• A presentation by Stephen Solis initiated a discussion on RoCoF (Rate of Change of Frequency) and phase angle jump requirements, emphasizing the need for clarity and consistency in measurement methods.
• Referenced ongoing discussions within IBRWG and NOGRR245, aiming for rule changes in line with IEEE 2800 standards.
• Highlighted current IEEE 2800 guidelines on RoCoF, specifying that the averaging window must be at least 0.1 seconds, but not defining an upper limit.
• Reviewed key points from the latest guidance from the P2800-2 drafting team regarding RoCoF and fault-related measurements.
• Emphasized the need for consistent measurement methods and sufficient time delays to prevent erroneous triggers.
• Need for discussion to define averaging window and to verify that 5hz/s is sufficient for ERCOT interconnection
• Discussed recent event analysis (e.g., Odessa 2022) showing that the current 0.1-second window might not be adequate.
• Introduced that validating and properly modeling capabilities may be important to verify IBR’s ability to ride-through load rejection and UFLS/UVLS simulations.
• Explored the potential for using a half-second averaging window to improve the reliability of RoCoF measurements.
• Transitioned to discussing phase angle jumps, referencing specific sections of IEEE 2800-2022 guidelines and identifying measurement challenges.
• Shared insights from the P2800-2 drafting team on phase angle jumps, similar to RoCoF in terms of guidance but differing in specific application.
• Highlighted that phase angle measurement should exclude fault events and should focus on post-event performance.
• Emphasized the need for consensus and further discussions to draft appropriate rule changes for and to refine the measurement methods for both RoCoF and phase angle jumps.

7 – Draft DWG Procedure Manual Edits/ Comments ERCOT/ Southern Power/ Luminant/ All

• Sun Wook with ERCOT transmission planning gave the DWG presentation
• Since March, DWG, IBRG, and ERCOT have collaborated on developing testing methods as outlined in NOGRR245.
• Comments were received from Southern Power and Luminant after the July 20 workshop, leading to a one-month extension for review.
• The presentation covered responses to these comments and minor modifications made to the manual.
• Southern Power requested more time for review, with ERCOT agreeing but stressing the importance of timely ROS approval.
• Emphasis was placed on the generation owners’ responsibility to meet ERCOT rules and on the benefits of early testing with new IBR curves.
• Southern Power suggested aligning the effective date of the ride-through test with the NPRR245 deadlines, which ERCOT acknowledged.
• Clarification was given that the DWG manual is for technical guidance, not for defining deadlines or exemptions.
• Both legacy and new IBR units must undergo testing with both the legacy and the new voltage dip test curves.
• ERCOT added a new voltage dip in the test curve to improve efficiency and address operational feedback.
• The preferred ride-through curve was renamed the “voltage dip test curve” to better reflect its function.
• Southern Power raised concerns about maintaining accurate models, which ERCOT addressed by emphasizing the generation owner’s responsibility.
• Updates were made to the DWG manual based on Luminant’s suggestion to use actual IBR settings in modeling.
• ERCOT clarified that the piecewise testing for the prepared IBR curve is not a new concept and offered assistance in performing the tests.
• Stakeholders were asked to review the updated DWG manual and submit comments by August 16.
• The final step is the recommendation of the DWG manual for approval at the September ROS meeting.

Q&A

• Andrew Nigro, Invenergy, expressed confusion about the timeline for submitting capability reports and performing new tests. He asked when he could start testing with updated models, given that the manual is still in draft.
  • Sun Wook responded, clarifying that the timeline for submitting models and tests is defined in the planning guide and the DWG manual. If there are no changes or updates needed, there is no requirement to submit anything new.

• Katie Rich from Luminant raised a concern about the difference between preferred and legacy curves for high and low voltage and questioned why both tests are necessary, given the costs involved in running additional tests.
  • Sun Wook explained that both curves provide different valuable data. He mentioned that Jonathan would provide more detailed explanations in his presentation.

• Carol Chessmore, Oncor, asked if TSPs should encourage new generation facilities to implement new tests before NOGRR245 becomes effective, even though it’s not yet required.
  • Sun Wook agreed that it could be beneficial to start early testing, even if not required, as the requirements are mostly settled.

• Kristen Cook, Southern Power, followed up on Carol’s question, asking for clarification on when the procedure manual becomes effective relative to NOGRR245. She expressed concern about ongoing modeling work being disrupted by new requirements.
  • Sun Wook clarified that the DWG manual will be effective once NOGRR245 is effective, and there will be notes or watermarks in the manual to indicate this.

• Carol Chessmore, Oncor, asked whether there would be a section in the manual that indicates if a generator is exempt from certain requirements
  • Stephen Solis from ERCOT clarified that any exemptions granted would only apply to the portion that does not meet the requirements, not the entire requirement set.

• Miguel Costa, Vestas, raised concerns about the thermal and mechanical stress caused by consecutive testing of voltage dips, suggesting the need for more flexibility in testing intervals.
  • Jonathan Rose, ERCOT, responded that the DWG manual allows for spacing between disturbances to allow for recovery and that the intention is not to test multiple fault events but to test the profile effectively.

• Miguel Costa further discussed potential issues with reactive current injection and suggested more discussion might be needed to refine the testing approach.
  • Jonathan Rose acknowledged the concern and agreed to discuss it further, emphasizing the need for testing that benefits the grid while also accommodating the unique characteristics of different equipment.
• Jonathan Rose and the meeting facilitators thanked the participants for their feedback and contributions to the discussion.

8 – Other Industry Updates – Julia Matevosyan – ESIG

• Meeting on July 30 discussed OEM readiness for IEEE 2800 by three OEMs.
• Presentation recordings related to NOGRR245 and inverter capabilities are available.
• Links provided for recordings, a webinar on grid forming capabilities from SMA, and a session on interconnection and modeling requirements.