NOTICE DATE: June 23, 2025 

NOTICE TYPE: M-B062325-01 Operations 

SHORT DESCRIPTION:  Large Load Survey and Request for Information of Voltage Ride-Through Capabilities to Ensure Reliable Interconnection and Operation of Large Electronic Loads

INTENDED AUDIENCE: All Market Participants and all Customers seeking interconnection of data center and crypto-mining Large Loads (75 MW or greater) 

LONG DESCRIPTION:  As discussed at ERCOT's June 13, 2025 Large Load Workshop and at the June 25, 2025 PUC Open Meeting, ERCOT is requesting information related to voltage ride-through capabilities to ensure the reliable interconnection and operation of data center and crypto-mining loads 75 MW or greater in size ("Large Electronic Loads" or "LELs"). The goal of this process is to continue facilitating the growth of LELs while protecting the reliability of the ERCOT System.

BACKGROUND

As previously noted in several presentations to the Large Flexible Load Task Force beginning in 2022, ERCOT has identified a risk to system reliability associated with the failure of certain LELs to ride through significant voltage disturbances.  During these events, the loss of load contributes to a sudden increase in the local voltage and to the system frequency, which could cause generators and other loads to trip offline, potentially resulting in cascading outages across the ERCOT System.   

With the growing number and size of LELs interconnecting to the ERCOT System, the possibility that many of these new LELs may lack the capability to ride through transmission fault conditions presents an increasing risk to system reliability.  Because ERCOT is required by the Public Utility Regulatory Act (PURA) to "ensure the reliability and adequacy of the regional electrical network," PURA section 39.151(a)(2), ERCOT must take action to mitigate these potential risks.

ERCOT's recent studies have concluded that, under certain operating conditions, the maximum amount of load loss that can be sustained on a system-wide basis without exceeding the post-contingency frequency limit is approximately 2,600 MW.  It is therefore essential for ERCOT to have accurate models of LELs so that it can assess grid stability risks.  ERCOT's observation from recent operational events demonstrates that the dynamic models currently representing many of these LELs do not reflect their actual dynamic performance.   

LARGE LOAD SURVEY AND INTERIM RIDE-THROUGH ASSESSMENT

ERCOT is requesting Customers with LELs to complete the ERCOT Dynamic Working Group (DWG) Large Load Survey, which was posted to the DWG meeting page on May 19, 2025.  The response to this survey will be used by ERCOT, in coordination with the interconnecting Transmission and/or Distribution Service Provider (TDSP), to determine whether any changes to the LEL's dynamic model information are needed.  Customers will be required to submit updated models if their survey results indicate such an update is needed.

SUBMISSION PROCESS FOR LARGE ELECTRONIC LOADS ALREADY ENERGIZED

For any LEL that, as of June 13, 2025, is energized or has already been approved by ERCOT to energize, ERCOT will seek the survey information through a Request for Information (RFI) sent to the interconnecting TDSP for the LEL.  For those cases in which the LEL has additional load that was evaluated in its interconnection studies that was not approved to energize as of June 13, 2025, the RFI will apply only to the portion of the load that has already received approval to energize.  ERCOT will send the RFI by June 30, 2025, and TDSPs will be requested to respond to the RFI by August 31, 2025.  Customers should cooperate with the TDSP to ensure the TDSP's response to the RFI is accurate, complete, and timely provided.  Failure to timely submit the information may require ERCOT to use conservative assumptions for the ride-through capability of the LEL.

SUBMISSION PROCESS FOR OTHER LARGE ELECTRONIC LOADS

For LELs that have not yet been approved to energize--including any additional portions of a Customer's LEL load that have not yet been approved to energize pending the completion of one or more transmission system upgrades, any LEL that has been studied through the LLIS process but that has not yet been approved to energize, and any LEL whose LLIS studies are not yet complete--the Customer or the Interconnecting Large Load Entity (ILLE), as appropriate, must provide the survey information for the load (or portion thereof that has not yet been authorized to energize) to ERCOT and the interconnecting TDSP (and lead TDSP, if different) and update its dynamic model to align with the survey information before requesting energization.    

Following the submission of any updated dynamic model information, the lead TDSP responsible for the LLIS should include the new information in the LEL's stability study.  If that study has already begun or has been completed, the TDSP must determine whether a new stability study using the updated information may be needed. If a new stability study is needed, that study must be submitted to and approved by ERCOT as a condition for energization. 

ERCOT will also conduct an interim assessment of each LEL's ride-through capability as a condition for energization.  ERCOT may require the ILLE or Customer to provide information that confirms the LEL's dynamic model accurately reflects the LEL's dynamic characteristics.  If the LEL's dynamic model information is different from the information that was studied in the LEL's LLIS stability study, the TDSP will need to evaluate whether a new stability study is needed.  

ACTION REQUIRED:  For Customers with LELs that are already energized or that have been approved to energize:  ERCOT will formally request responses to the survey and model updates in an RFI sent no later than June 30, 2025.  Once the RFI has been issued, the Customer should coordinate with its interconnecting TDSP to complete the ERCOT DWG Large Load Survey and provide any necessary dynamic model updates to ERCOT by August 31, 2025.  Directions for responding to the survey will be included in the RFI. 

For Customers or ILLEs with LELs that have not yet been approved to energize (in part or in whole, as further described in this Notice):  The Customer or ILLE should complete the ERCOT DWG Large Load Survey and, if necessary, update its dynamic model and provide that information to ERCOT, the interconnecting TDSP, and the lead TDSP.  ERCOT will not issue an RFI to these Customers or ILLEs but will instead require this information to be provided as a condition for energization.  Survey responses should be sent to LargeLoadInterconnection@ercot.com.  

All Customers with LELs and all ILLEs with LELs should continue to provide updates to their survey responses and dynamic models on an ongoing basis.  

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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