Power Issues and Trouble Shooting

CSU Emergency Load Shedding Procedure During an ERCOT Involuntary Load Shedding Event

As required by Texas Senate Bill 3 (SB3) and the Public Utility Commission of Texas (PUCT) Utilities Code Section 17.005, the following is a synopsis of the process designated by the Electric Reliability Council of Texas (ERCOT) for involuntary load shedding events.  CSU and all other electric utilities must follow this process in order to ensure the stability of the electric grid.  Failure to follow this process can result in failure of the ERCOT electric grid and massive fines to the utility. Typically, before calling for controlled customer outages, ERCOT takes steps to reduce the demand on the electric grid by asking customers to reduce electric usage. The Public Utility Commission of Texas website  (https://www.puc.texas.gov/consumer/facts/Save.aspx)  provides examples for customers to reduce electricity use at times when involuntary load shedding events may be implemented.

1. 25% of the system load is dedicated to Underfrequency Load Shed (UFLS) feeders.These are divided into three categories:
   • 5% at a set points of 59.3 Hz
   • 10% additional at a set point of 58.9 Hz
   • 10% additional at a set point of 58.5 Hz

   This load will shed automatically should the frequency hit the designated set point to try to stabilize the frequency on the ERCOT grid.

2. Feeders containing critical load are designated.This load will not be shed intentionally during a load shed emergency.Critical load is as follows:
   • Police Station (911)
   • Sewer lift station / treatment plant
   • Hospitals / Nursing Homes
   • Water facility pump station
     
     
3. All other feeders are designated for rolling outages.The goal is to keep rolling outages to a 15-to-30-minute duration but may be extended depending upon the situation.The length of time and magnitude of load to be shed (which affects the time between outages) during a rolling outage event is designated by ERCOT.