NOTICE DATE: July 16, 2024

NOTICE TYPE: M-A071624-01 Operations

SHORT DESCRIPTION: Investigation of Incorrect Ancillary Service Failed Quantity Calculations

INTENDED AUDIENCE: All Market Participants

DAYS AFFECTED: June 28, 2024 to present

LONG DESCRIPTION: ERCOT has identified an issue in the logic being used in the calculation of Ancillary Service Failed Quantity Calculations.  A telemetry snapshot is taken with each run of Security Constrained Economic Dispatch (SCED) to determine if a Qualified Scheduling Entity's (QSE's) Ancillary Service Supply Responsibility is being met by resources in their portfolio.  The first SCED run for an Operating Hour usually occurs several seconds after the top of the hour, however the telemetry snapshot being used for the first several seconds is from the last SCED run in the previous Operating Hour.  This may create relatively small but regular discrepancies in the comparison of Ancillary Service Resource Responsibilities with Ancillary Service Supply Responsibilities, and in turn lead to small, incorrect Ancillary Service Failed Quantities when a time-weighted average telemetered Resource Responsibility for each Ancillary Service over the Operating Hour is calculated. 

ERCOT is investigating a solution to this issue and will update the Market as the solution and associated timeline for implementation is determined.

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 ClientServices@ercot.com.

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