Adaptive Corrective Control Strategies for Preventing Power System Blackouts

In order to investigate power system security and design appropriate control strategies, power systems can be conceptually classified into five operational states: Normal, Alert, Emergency, In Extremis, and Restorative. Various preventive and corrective control strategies have been studied to cope with power systems in the different operational states. Our approach primarily focuses on the corrective control strategies for power systems under emergency and in extremis states. In this paper, two corrective control approaches (transmission system reconfiguration and controlled system islanding) have been investigated and new algorithms have been developed. When the system is in the emergency state, two reconfiguration strategies, line switching and bus-bar switching, have been presented to solve the problems of overloads or voltage violations. Furthermore, to prevent a total system black out, a slow coher-ency grouping based adaptive power system islanding approach using minimal cutsets has been presented to deal with catastrophic events when power system vulnerability analysis indicates that the system is approaching the in extremis state. A controlled under frequency load shedding scheme with the rate of frequency decline is also proposed to balance the real power within each island and aid restoration. The verification of our approach is proven with simulations on a 179-bus, 29generator WECC system.