NOTICE DATE: September 11, 2024
NOTICE TYPE: M-A091124-01 Operations
SHORT DESCRIPTION: Potential Price Correction – Usage of incorrect Resource telemetry MW values when QSE sends suspect quality telemetry, for SCED Mathematical limit computations for active constraints.
INTENDED AUDIENCE: All Market Participants
DAYS AFFECTED: September 5, 2024
LONG DESCRIPTION: On September 5, 2024 at approximately 8:35 AM, Multiple Resources represented by a single Qualified Scheduling Entity (QSE) telemetered suspect quality measurement on their MW telemetry. When this occurs, the Energy Management System (EMS) should use the last known good telemetered value and send it to Security-Constrained Economic Dispatch (SCED) for SCED Mathematical limit computation for active constraints. Instead, due to a software defect in EMS, if a Resource's MW telemetry became suspect quality, EMS sent much older Resource MW values as telemetered Resource MW values to SCED. When SCED ran at 08:35:10, the incorrect Resource telemetry MW values impacted the optimization and resulted in System Lambda spiking from $20.99/MWh to $199.17/MWh. System Lambda returned to $27.88/MWh following the 08:40:09 SCED run after the telemetered values were no longer suspect.
After an initial investigation, it was found that the software defect was introduced into the EMS in November 2023. A fix for the defect was implemented on September 11, 2024 at 11:40 AM to address this issue and keep the last good telemetered Resource MW for SCED Mathematical limit computation for active constraints when Resource MW telemetry goes suspect.
If ERCOT determines that Real-Time Market (RTM) prices qualify for a correction and seeks review of such prices by the ERCOT Board of Directors (ERCOT Board), ERCOT must notify Market Participants no later than 30 days following the Operating Day (OD); see ERCOT Protocol Section 6.3(7)(a).
While ERCOT continues to investigate the impact on RTM prices, this Market Notice is being issued to preserve the eligibility of the ERCOT Board to review prices for the affected ODs that are within 30 days of this notice. ERCOT will provide Market Participants with a follow-up Market Notice with more information concerning pricing impacts and whether ERCOT will be seeking ERCOT Board review.
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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