SHORT DESCRIPTION: Potential Price Correction - Generic Transmission Constraint (GTC) Calculation Error Impacting Real-Time Market (RTM)

LONG DESCRIPTION: On February 7, 2023, ERCOT became aware of an error related to the calculation of the Valley Export GTC (VALEXP) in the RTM. The error caused the GTC to incorrectly bind during multiple Security-Constrained Economic Dispatch (SCED) intervals on February 5 and 6, 2023, and consequently impacted RTM prices on those Operating Days. During this time window, the limit on the constraint was lower than its usual value due to a transmission outage, and there were instances in which the flow on the constraint was changing direction rapidly. When the flow reversed direction, the data sent to SCED was incorrect and did not reflect the change in direction.

Pursuant to Protocol Section 6.3(3), ERCOT issued a public notice on February 7, 2023, that prices for the Operating Days impacted by the calculation error on the GTC were under investigation. Pursuant to Protocol Section 6.3(5), ERCOT corrected prices for Operating Day February 6, 2023, before prices became final and issued a public notice on Feb 8, 2023, informing Market Participants of this correction.

ERCOT has performed additional analysis and determined that the calculation error described above impacted RTM prices for February 5, 2023, and that these impacts meet the criteria of significance for review by the ERCOT Board of Directors (ERCOT Board) pursuant to Protocol Section 6.3(7)(b). Information on the number of Counter-Parties meeting the Protocol criteria is provided in the table below. When ERCOT determines there is a need for an RTM price correction after prices are final and intends to seek review of such prices by the ERCOT Board, ERCOT must notify Market Participants no later than 30 days following the relevant Operating Day under Protocol Section 6.3(7)(a).

ERCOT intends to seek ERCOT Board review of RTM prices for Operating Day February 5, 2023, at the Reliability and Markets Committee meeting on April 17, 2023, and the regular ERCOT Board meeting on April 18, 2023.

Operating Day	Counter-Parties meeting criteria in Protocol Section 6.3(7)(b)(i)*	Counter-Parties meeting criteria in Protocol Section 6.3(7)(b)(ii)*
02/05/2023	2	3

* Under Protocol Section 6.3(7)(b), ERCOT shall seek ERCOT Board review of prices if the change in RTM Settlement Statement(s) would result in the absolute value impact to any single Counter-Party (CP), based on the sum of all original RTM Settlement Statement amounts of Market Participants assigned to the CP, to be greater than either: (i) 2% and also greater than $20,000; or (ii) 20% and also greater than $2,000.

ADDITIONAL INFORMATION: Supporting documents and re-calculated prices will be included in materials for the Reliability and Markets Committee and ERCOT Board meetings in April.

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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