NOTICE DATE: October 29, 2021

NOTICE TYPE: W-C102921-01 Operations

SHORT DESCRIPTION: Potential Price Correction - Generic Transmission Constraint (GTC) Modeling Error Impacting the Day-Ahead Market (DAM)

INTENDED AUDIENCE: All Market Participants (MPs)

DAYS AFFECTED: Operating Days (ODs) September 30 to October 12, 2021

LONG DESCRIPTION: On October 13, 2021, ERCOT became aware of a data input error related to the modeling of the North Edinburg to Lobo (NE_LOBO) GTC in the DAM. ERCOT determined that the GTC was incorrectly defined in the DAM for ODs September 30 to October 13, 2021, and that this error may have impacted prices on those ODs. ERCOT corrected the GTC definition in the DAM effective for OD October 14, 2021. This issue did not impact Real-Time Market prices.

Pursuant to Protocol Section 4.5.3(5), ERCOT corrected prices for OD October 13, 2021, before prices became final, and issued a public notice on October 14, 2021, informing Market Participants of this correction.  Further, pursuant to Protocol Section 4.5.3(3), ERCOT issued public notices on October 15 and 22, 2021, stating that prices for the remaining ODs impacted by the incorrectly defined GTC—i.e., September 30 to October 12, 2021—were under investigation.

ERCOT has now determined that the data error described above impacted DAM prices for certain ODs to a degree that qualifies the ODs for review by the ERCOT Board of Directors (ERCOT Board) pursuant to the criteria set forth in Protocol Section 4.5.3(6)(b), as detailed in the table below.  When ERCOT determines there is a need for a DAM 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 OD. See ERCOT Protocol Section 4.5.3(6)(a).

ERCOT intends to seek ERCOT Board review of DAM prices for the following ODs at the December 9 or 10, 2021, ERCOT Board meeting: September 30, 2021, and October 6 to 12, 2021.  ERCOT also intends to discuss this issue at the November 17, 2021, meeting of the Technical Advisory Committee.     

Operating Day (OD)	CPs meeting criteria in Protocol Section 4.5.3(6)(b)(i)*	CPs meeting criteria in Protocol Section 4.5.3(6)(b) (ii)*
09/30/2021	2	10
10/06/2021	0	1
10/07/2021	0	4
10/08/2021	1	1
10/09/2021	1	9
10/10/2021	14	26
10/11/2021	1	7
10/12/2021	9	14

 

* Per Protocol Section 4.5.3 (6)(b), ERCOT must seek Board correction of DAM prices for an OD if the absolute value impact of the price correction on any single Counter-Party (CP) -- based on the sum of all original DAM Settlement Statement amounts of MPs assigned to the CP for the OD -- is greater than either: (i) 2% and also greater than $20,000; or (ii) 20% and also greater than $2,000.

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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