NOTICE DATE: January 31, 2026

NOTICE TYPE: M-A013126-01 Operations

SHORT DESCRIPTION: Optional, Final Ad Hoc Interim Voltage Ride-Through Assessment for Large Loads Requesting Initial Energization Before July 1, 2026

INTENDED AUDIENCE: Interconnecting Large Load Entities (ILLEs) and ERCOT Market Participants

DAYS AFFECTED: February 27, 2026

LONG DESCRIPTION: ERCOT will conduct an optional, final ad hoc interim voltage ride-through (VRT) assessment, in lieu of a Quarterly Stability Assessment (QSA), for any Large Loads that, as of January 28, 2026, have met all requirements of Sections 9.4 and 9.5 of the ERCOT Planning Guide, have requested Initial Energization dates on or before June 30, 2026, and have not yet been evaluated through either ad hoc interim VRT assessment performed in 2025.  ERCOT provides this option to ensure that VRT performance and the impact on system reliability of interconnecting these Large Loads can be evaluated while maintaining their requested Initial Energization dates.  ERCOT has determined that Large Loads with requested Initial Energization dates on or before June 30, 2026 should not reasonably be subject to the new Quarterly Stability Assessment (QSA) requirement for Large Loads in Sections 5.3.5 and 9.6 of the ERCOT Planning Guide because that would require them to comply with the QSA prerequisites by the deadlines established in Section 5.3.5(2) of the ERCOT Planning Guide, and those prerequisites did not exist when those deadlines (August 1, 2025 and November 1, 2025) passed, making it impossible for these projects to qualify for the QSAs that would align with their requested Initial Energization dates.  The Large Load QSA requirement and the QSA prerequisites for Large Loads both came into effect when PGRR115 was implemented on December 15, 2025. 

This final ad hoc interim VRT assessment will serve as the culmination of the process that was announced in Market Notice M-B062325-01.  As explained in that notice and in Market Notice M-B100825-01, each Large Electronic Load (LEL) project energizing after June 23, 2025 has been required to participate in an interim VRT assessment as a condition for energization.  As a condition for being included in an interim VRT assessment, LELs have been required to complete the Dynamics Working Group (DWG) Large Load Survey and submit to the interconnecting TDSP and ERCOT dynamic models reflecting the LEL's ride-through performance.  ERCOT has conducted two ad hoc interim VRT assessments for LELs to date.  Going forward, ERCOT will continue assessing VRT impacts as part of the Quarterly Stability Assessment (QSA).  No further ad hoc interim VRT assessments will be offered.

This final, ad hoc interim VRT assessment will be available for Large Loads that, as of January 28, 2026, have completed all requirements in Sections 9.4 and 9.5 of the Planning Guide, have a requested Initial Energization date of June 30, 2026 or before, and have not yet been evaluated through either ad hoc interim VRT assessment performed in 2025.  Large Loads that wish to be evaluated as part of this final ad hoc interim VRT assessment must complete the DWG Large Load Survey and also submit to the interconnecting TDSP and ERCOT dynamic models reflecting the Large Load's ride-through performance no later than February 27, 2026.  The ILLE must submit the DWG survey and dynamic model to its interconnecting TDSP and to ERCOT via email to largeloadinterconnection@ercot.com along with a request to be included in this final ad hoc interim VRT assessment.  The survey and all model information must be acceptable and in good quality by this date or the Large Load will not be included in this assessment. If an ILLE that wishes to be included in this assessment is uncertain about the quality of its survey and model information, it should reach out to ERCOT as soon as possible to avoid any concern with meeting this firm deadline.

ERCOT anticipates completing the assessment by the end of April 2026.  Large Loads that have planned energization dates in April 2026 or before that have not been evaluated in an interim VRT assessment will likely need to change their scheduled energization dates to May or June 2026. 

Large Loads participating in the interim VRT assessment will also need to meet all other conditions for energization, including completion of a Subsynchronous Oscillation (SSO) study and implementation of any required SSO Mitigation.  Inclusion in this final interim VRT assessment does not guarantee energization by June 30, 2026.  If the interim VRT assessment identifies a stability concern with the energization of the Large Load, energization will be conditioned on implementation of an appropriate System Operating Limit (SOL) or Interconnection Reliability Operating Limit (IROL).

Large Loads that are not included in this VRT assessment will be required to go through the QSA process prior to requesting Initial Energization, as described in Sections 5.3.5 and 9.6 of the ERCOT Planning Guide.  The first such QSA will apply to Large Loads with requested Initial Energization dates in July, August, and September 2026.  As provided in Section 5.3.5 of the ERCOT Planning Guide, the deadline for meeting the conditions to be included in this QSA is February 1, 2026. 

ACTION REQUIRED: Any ILLE that wishes to include its eligible Large Load in this final ad hoc interim VRT assessment must complete the DWG Large Load Survey and submit it to the interconnecting TDSP and ERCOT along with dynamic models reflecting the Large Load's ride-through performance and a request to be included in this final ad hoc interim VRT assessment.  The information must be submitted to ERCOT at largeloadinterconnection@ercot.com no later than February 27, 2026.  

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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