Adaptive protection as preventive and emergency control

Recent advances suggest expanding the concept of power system protection to “adaptive protection.” It is important to recognize that both “demand pull” and “technology push” drive this trend. A literature survey from 1988 to 1999 shows adaptive relaying ideas have advanced from early concepts to experiments in wide-area emergency control. A wide-area control system contains three hierarchical levels of protection and control-local, substation and interconnected wide area. At least two operating scenarios are conceivable. Under the first scenario, one anticipates vulnerabilities and positions the system to be more robust in the event of a threat or hidden failures. The second scenario calls for the system to respond to failure events by, for example, modifying the protection system to defend against future events in case of a component failure. To complete this concept of adaptive protection as a preventive and emergency controller, it remains to identify the important issues. This paper identifies, for each level, the control action necessary and the system required to implement that control