Emergency Control Practices

The Emergency Control Task Force was formed in February 1982. In order to clarify and focus its efforts, the Task Force, as its first order of business and after considerable discussion, adopted the following definitions as a basis for its deliberations: Power System Emergency: A condition or state of system operation characterized by one or more violations of "hard" inequality constraints (e.g., short or long term emergency ratings) on the bulk power system. An emergency generally is an indication of a viability crisis and/or a stability crisis. A viability crisis results from an imbalance between generation, loads, and transmission, whether local or system-wide. A stability crisis results from energy accumulated at sufficient level in swings of the system to disrupt its integrity. Power System Failure: A condition or state of system operation characterized by loss of system integrity involving uncontrolled islanding (fragmentation) of the system and/or uncontrolled loss of large blocks of load.