New Wide-Area Algorithms for Detection and Mitigation of Angle Instability using Synchrophasors

Electric power system is undergoing major technological advances with many new installations of synchrophasors across the North American grid as well in power systems all over the world. Wide-area monitoring system (WAMS) in the Pacific Northwest and the Eastern Interconnection Phasor Project (EIPP) in the eastern grid are examples of such installations. Synchrophasors together with modern communication technology facilitate the monitoring of the current state of the power system including the phase angles of the bus voltages at critical buses in a time-synchronized fashion. The algorithms and the controller proposed in this paper detect the fast separation of phase angles among the critical areas automatically by using the synchrophasors, and proceed to mitigate the emerging angle instability by triggering suitable control action. Briefly, the algorithms initiate tripping of critical generators in the accelerating part of the system when necessary, and also initiate load shedding in the decelerating part of the system whenever necessary. The novelty of the algorithms is in the fact that all the decisions are made in real-time purely based on the wide-area synchrophasor measurements without any knowledge of the details of relay actions that may have resulted in the angle instability phenomenon.