NOTICE DATE: April 30, 2021
NOTICE TYPE: W-A042021-02 Operations
SHORT DESCRIPTION: Update: Shift Factors Record Size Limitation Impacting SCED
INTENDED AUDIENCE: All Market Participants
DAYS AFFECTED: April 1 to April 20, 2021
LONG DESCRIPTION: On April 20, 2021, ERCOT issued Market Notice W-A042021-01 to inform Market Participants of an issue in the Energy Management System (EMS) that impacted Security-Constrained Economic Dispatch (SCED) for Operating Days (ODs) April 1 to April 20, 2021. ERCOT implemented an emergency software update at 00:00 on April 21, 2021, and resolved this issue. As explained in the prior Market Notice, a small number of Resources were not dispatched correctly by SCED for any active constraints during the impacted ODs, because their Shift Factors were not passed from ERCOT’s Real-Time Contingency Analysis to SCED.
This update provides the list of Resources that were impacted by this issue, as well as the Operating Days (ODs) for which the Resources were impacted, as reflected in the table below.
| Station |
Resource |
Impacted ODs |
| WH_WIND |
UNIT1 |
Apr. 1 - Apr. 20 |
| WH_WIND |
UNIT2 |
Apr. 1 - Apr. 20 |
| WL_RANCH |
UNIT1 |
Apr. 1 - Apr. 20 |
| TRENT |
TRENT |
Apr. 7 - Apr. 20 |
| TRENT |
UNIT_2 |
Apr. 7 - Apr. 20 |
| TRENT |
UNIT_3A |
Apr. 7 - Apr. 20 |
| TRENT |
UNIT_3B |
Apr. 7 - Apr. 20 |
| TTWEC |
G1 |
Apr. 7 - Apr. 20 |
| TKWSW1 |
ROSCOE |
Apr. 14 - Apr. 20 |
| TRENT |
UNIT_1B |
Apr. 14 - Apr. 20 |
A small number of Electrical Buses and Loads were also impacted by this issue. Although SCED does not directly use Electrical Bus Shift Factors to dispatch any Resource, it does use Electrical Bus Shift Factors to calculate the Electrical Bus Locational Marginal Prices (LMP), which then are used in the downstream calculation for Real-Time Settlement Point Prices (RTSPPs) and Real-Time Prices for Energy Metered for Resources (RTRMPRs). Similarly, SCED uses Load Shift Factors to calculate the Load Zone LMPs, which then are used in the downstream calculation for RTSPPs for Load Zones. The list of Electrical Buses and Loads with missing Shift Factors during the impacted ODs can be found in the attachment to this Market Notice. As explained in the prior Market Notice, ERCOT is not seeking review of prices for the impacted ODs by the ERCOT Board of Directors, because any effort to recalculate prices would require ERCOT to make significant assumptions concerning the operating behavior of individual Resources, such that accurate prices cannot be determined.
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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