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NOTICE DATE:  February 19, 2021

NOTICE TYPE:  W-B021921-02 Operations

SHORT DESCRIPTION:  Re-evaluation of maximum Shadow Price for an irresolvable constraint in SCED


DAY AFFECTED:  February 20, 2021

LONG DESCRIPTION:  On February 19, 2021, ERCOT re-evaluated the maximum Shadow Price for an irresolvable constraint that had accumulated a net margin larger than $95,000/MW, per the criteria defined in in Section 3.6.2 of the Other Binding Document (OBD), Methodology for Setting Maximum Shadow Prices for Network and Power Balance Constraints.

Per the calculations described in the OBD, the maximum Shadow Price was re-determined as $2,000, in accordance with Section 3.6.2 of the same OBD. The update to the maximum Shadow Price will be implemented between 10:00AM and 11:00AM Central Prevailing Time (CPT) on February 20, 2021. The contingency/constraint pair and maximum Shadow Price are as follows:

Contingency Name

Constraint Name

From Station/kV


Maximum Shadow Price




Loss of the JOHNSON SWITCH (ONCOR) to CONCORD 345kV Single Circuit overloads the 138kV Line from DECORDOVA DAM to CARMICHAEL BEND SWITCH

2,000 $/MWh


This new maximum Shadow Price will be used for all constraints in Security Constrained Economic Dispatch (SCED) which share the same monitored element (i.e. constraint name) and direction.

ADDITIONAL INFORMATION:  The ERCOT business practice document, Setting the Shadow Price Caps and Power Balance Penalties in Security Constrained Economic Dispatch, can be found in the Methodology for Setting Maximum Shadow Prices for Network and Power Balance Constraints under Key Documents on the Real-Time Market webpage, and under the Other Binding Documents List, both of which are on the ERCOT website.

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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