NOTICE DATE: April 4, 2022
NOTICE TYPE: M-A040422-01 Operations
SHORT DESCRIPTION: Issue with the Three-Part Supply Offers used in the Reliability Unit Commitment (RUC) Optimization
INTENDED AUDIENCE: All Market Participants
DAYS AFFECTED: June 22, 2016, through March 30, 2022
LONG DESCRIPTION: ERCOT staff has identified an error in the RUC process. The issue stems from a parameter setting that caused the RUC optimization to consider incorrect startup and minimum energy costs for some Resources. It has been determined that the setting error was most likely introduced with the implementation of Nodal Protocol Revision Request (NPRR) 617, Energy Offer Flexibility, implemented in 2016. For the RUC process, this error incrementally reduced the amount of Resource commitment recommended by the optimization in some cases. It has been confirmed that this issue impacted only the RUC optimization and did not feed into RUC settlement. Consequently, this also would not have directly impacted Day-Ahead Market (DAM) or Real-Time Market (RTM) pricing outcomes or any associated Settlement.
The identified issue impacted the calculation of certain Resources’ startup and minimum energy costs in the process of DRUC/HRUC in the following two ways:
System functionality before correction
If Three-Part Supply Offer not available, create the startup and minimum energy costs using:
225% of verifiable costs, if verifiable costs available; or
150% of generic costs, if verifiable costs not available
Correct system functionality
If Three-Part Supply Offer not available, create the startup and minimum energy costs using:
150% of verifiable costs, if verifiable costs available; or
150% of generic costs, if verifiable costs not available
System functionality before correction
If Three-Part Supply Offer available, cap the minimum energy and startup costs to:
Min (Offer, Max(150% of verifiable costs, 100% of generic costs))
Correct system functionality
If Three-Part Supply Offer available, cap the minimum energy and startup costs to:
Min (Offer, Max(100% of verifiable costs, 100% of generic costs))
ADDITIONAL INFORMATION: This error was corrected in production systems on Operating Day March 31, 2022. Given that this issue did not affect RUC settlement or DAM and RTM pricing more generally, ERCOT will not be correcting any prices or performing any Market resettlement.
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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