Fast acting load shedding

The fast acting load shedding (FALS) function was developed to fulfil a need for a statewide relay that detects a system disturbance that is stable but results in lines operating beyond their ratings, low system voltages, and heavy reactive demand on generating units. The FALS function then sheds enough customer load in a short amount of time to prevent a cascading loss of a line or generator with the possibility of a blackout. The FALS function uses the System Control Center computers and statewide supervisory control and data acquisition (SCADA) communications to act as a really that detects this specific type of disturbance and initiates a controlled load shed. The authors describe the system conditions necessitating the development of the FALS function, the design criteria, its computer implementation, operating experience, and known deficiencies