NOTICE DATE: October 29, 2025

NOTICE TYPE: M-A100925-02 Operations

SHORT DESCRIPTION: Live production two-hour test for RTC+B closed-loop frequency control on October 30, 2025 between 10:00 am-13:00 pm

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: October 30, 2025 for two hours between 10:00 am -1:00 pm 

LONG DESCRIPTION:  This notice is to confirm that the live production two-hour closed-loop test of Real-Time Co-optimization Plus Batteries (RTC+B) is planned for October 30, 2025 to occur between 10:00 am-1:00 pm.  

As previously communicated, ERCOT has been working with Qualified Scheduling Entities (QSEs) with Resources to implement and test new telemetry and market submissions into the RTC+B systems.  This production test will be based on QSE RTC+B telemetry, market submissions, and the ability of Resources to follow ERCOT Dispatch Instructions from RTC+B's Security-Constrained Economic Dispatch (SCED) every five minutes and Load Frequency Control (LFC) every four seconds to manage the ERCOT dispatch and frequency.

On October 30, 2025, the ERCOT Control Room will issue hotline calls to coordinate the test and QSEs should be adequately staffed and prepared to support the testing in accordance with the prescribed activities in the RTC+B LFC Handbook in terms of:

• Control room operations;
• Accurate telemetry support, including support of any submissions affecting telemetry (e.g., Current Operating Plans (COP));  
• Resource control for Generation Resources, Load Resources, and Energy Storage Resources; and
• Market submissions in alignment with the prescribed offer requirements in the RTC+B LFC Handbook.

During the duration of the test, data on the ERCOT dashboards and reports will not be correct because those will reflect the non-RTC system data.

ACTION REQUIRED: For QSEs with Resources, below is the high-level summary of ERCOT's expectations and timeline for support as discussed at the Monday, October 27 Workshop for RTC+B LFC Closed-Loop LFC Testing :

• On October 29, 2025:
  • By 3:00 pm, QSE should have updated RTC+B systems with parallel production data for each Resource in their October 30, 2025 portfolio:
    • COP;
    • Ancillary Service Offers (ensure they are not set to expire before test and are in alignment with $0/$2,000 offer guardrail requirements, as specified in the RTC+B LFC Handbook ); and
    • Energy Offer/Bid Curves (ensure energy offer/bid are the same as production price and quantity)
  • ERCOT is targeting initial outreach at 4:00 pm to QSEs on any observed issues
  • ERCOT is targeting next outreach at 7:00 pm to QSEs on any observed issues
• On October 30, 2025:
  • ERCOT starts the secure WebEx with QSEs to establish direct communication from 7:00 am - 1:00 pm:
    • 7:00 am - 9:00 am: ERCOT and QSEs work to resolve any market submission issues and/or telemetry issues; and
    • 9:00 am - 1:00 pm: Coordination of real-time cutover and cutback

Lastly, a reminder that if the QSE has a Resource that cannot comply with RTC+B dispatch, the QSE can submit an exception request prior to the LFC test to the ERCOT Control Room using the NDCRC application (more details on slide 9 from Monday Workshop for RTC+B LFC Closed-Loop LFC Testing).

CONTACT: If you have any questions, please contact RTCB@ercot.com and/or your ERCOT Account Manager. You may also call the general ERCOT Client Services phone number at (512) 248-3900 or contact ERCOT Client Services via email at ClientServices@ercot.com.

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dg