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NOTICE DATE:  May 1, 2019

NOTICE TYPE:  W-B050119-01 Operations

SHORT DESCRIPTION:  Real-Time Shift Factor calculation error for certain Combined Cycle Generation Resources

INTENDED AUDIENCE:  ERCOT Market Participants

DAYS AFFECTED:  August 8, 2018 through May 1, 2019

LONG DESCRIPTION:  An error has been identified in the calculation of Real-Time Market (RTM) Shift Factors for two Combined Cycle Generation Resources: Odessa Ector Combined Cycle 1 and Combined Cycle 2 (OECCS_CC1 and OECCS_CC2).  For these specific Resources, Shift Factors for certain gas turbines were double-counted when ERCOT aggregated values to determine the Shift Factors for the Combined Cycle Trains.

ERCOT has determined that the error was introduced during a software release on August 8, 2018, which included an enhancement to address an unrelated deficiency in ERCOT's Energy Management System (EMS).  The software release inadvertently created the double-counting error for the aforementioned Resources.  This error did not impact Shift Factors for any other Resources.

The impact to the Shift Factors varied; however, ERCOT has determined that the error impacted the Shift Factor values for at least one of the Resources for all Operating Days between August 8, 2018 and May 1, 2019.

Although this issue may have affected prices, and dispatch to some extent, ERCOT is unable to perform price corrections because it cannot determine accurate prices, as any effort to recalculate new prices would require ERCOT to make significant assumptions concerning the operating behavior of individual Resources.

ERCOT implemented a software fix to address this error on May 1, 2019.

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]<mailto:[log in to unmask]>.

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