NOTICE DATE: September 20, 2021

NOTICE TYPE: M-B092021-01 Operations

SHORT DESCRIPTION: Disabling of contingency in Day-Ahead Market (DAM) to address identified performance issue

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: Operating Day (OD) September 20, 2021, until further notice

LONG DESCRIPTION: On September 19, 2021, the posting of the DAM solution for OD September 20, 2021, was delayed due to erroneous transmission violations being discovered during the DAM validation process.  Upon investigation, it was determined that the interaction of contingency SOKLRI25 with outages that began on OD September 20, 2021, resulted in a split Hub Bus that caused the erroneous transmission violations.  In order to correct this error, ERCOT employed a mitigation strategy that required disabling contingency SOKLRI25 and rerunning the DAM for OD September 20, 2021, before publishing the final DAM solution.  Please note this error does not impact clearing in Real-Time.

ERCOT will continue employing this mitigation strategy—that is, ERCOT will continue disabling contingency SOKLRI25 in the DAM—for all Operating Days going forward, until a software patch can be deployed to correct for the identified error.  ERCOT will provide further updates via another Market Notice when this software patch is implemented.

CONTACT: If you have any questions, please contact 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 [log in to unmask].

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