Distributed control with local and wide-area measurements for mitigation of cascading outages

Modern electric power systems are extremely reliable but occasionally suffer from cascading failures initiated by localized asset removal. As lines and transformers overload and are taken out of service by protective relays, the system can progressively weaken. Network interconnections then enable regional instability to expand into a wide area. Protective relays have unique information about initial outage causes and local behavior. This includes identifying whether the actions of the protective relays are related to fault conditions or overloads. Meanwhile, synchrophasor technology now provides wide-area information in real time. The combination of local and wide-area information that is time-synchronized provides the ability to stabilize electric power systems in ways that minimize necessary control actions. This paper describes the development of a control system that applies local information in coordination with synchrophasor measurements to assess the complete state of the power system and differentiate a local phenomenon from the possibility of an overload-related cascade. The system executes a set of actions to contain and minimize the event. This paper verifies the efficacy of the proposed control system algorithms against cascading line outage scenarios applied to an IEEE standard test system. Keywords—wide-area control, synchrophasors, cascading outage, phasor measurement unit, protective relay, intelligent electronic device, system integrity protection scheme