ERCOT Reports Internal Data Error May Have Impacted Real-Time Prices For Several Days In March (Includes Higher, Incorrect Offer Cap & Power Balance Penalty Curve Value)
ERCOT Won't Seek To Correct Prices; Says It Cannot Determine Accurate Prices Because Recalculation Would Require ERCOT To Make Significant Assumptions Concerning Operating Behavior Of Market Participants
April 20, 2021 Email This Story Copyright 2010-21 EnergyChoiceMatters.com
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ERCOT issued a market notice today stating, "On March 24, 2021, an internal data error occurred during a routine database load, which caused several Market Management System (MMS) parameters to be replaced with incorrect values. ERCOT discovered that this error may have impacted Real-Time Market (RTM) prices, due to the impact of the error on Security-Constrained Economic Dispatch (SCED)."
"More specifically, this error resulted in SCED executions between 00:35 on March 24, 2021, and 20:45 on March 26, 2021, using incorrect values for certain SCED parameters in some, but not all, SCED intervals," ERCOT said in the market notice
The notice included a table describing each of the impacted SCED parameters, its correct and incorrect values for the time period at issue, the time period during which incorrect values occurred, and a brief description of the potential impact on SCED. The table can be found here
As an example of the errors, an incorrect value of $2,250/MWh for the System-wide Offer Cap, rather than the correct $2,000/MWh, was applied for the intervals 3/24/2021 00:35 to 3/24/2021 00:55. This may have impacted proxy Energy Offer Curves (EOCs)
Another error was that the value for the Power Balance Penalty Curve was either $3,001/MWh or $5,000/MWh for the period 3/24/2021 00:35 to 3/26/2021 20:35, rather the correct values which should have ranged from $250/MWh to $2,001/MWh. This may have impacted SCED intervals when System Lambda exceeded the lowest price on the Power Balance Penalty Curve of $250/MWh
ERCOT said in the market notice that Proxy Energy Offer Curves impacted by this error will be reflected in the 60-day SCED disclosure reports for the relevant Operating Days.
"Because the error impacted SCED, RTM prices may have been impacted. ERCOT Protocol Section 6.3(4) requires ERCOT to correct RTM prices when, among other reasons, (i) a Market solution is determined to be invalid, (ii) invalid prices are identified in an otherwise valid Market solution, or (iii) the Base Points received by Market Participants are inconsistent with the Base Points of a valid Market solution, unless accurate prices cannot be determined," ERCOT said in the market notice
"Although the error may have affected prices during the impacted SCED intervals, ERCOT cannot determine accurate prices because any effort to recalculate prices would require ERCOT to make significant assumptions concerning the operating behavior of individual Resources over extended periods of time. Therefore, ERCOT will not seek review of RTM prices for the impacted Operating Days by the ERCOT Board of Directors," ERCOT said in the market notice
"Incorrect parameters were also put in the Day-Ahead Market (DAM) and Reliability Unit Commitment (RUC) applications as part of the routine database load process. However, these parameters were corrected before impacting results for either the DAM or RUC," ERCOT said in the market notice
"ERCOT has made changes to its database load processes to address similar concerns moving forward. Changes from the vendor are also being pursued to further mitigate future concerns," ERCOT said in the market notice