A PMU-based monitoring scheme for rotor angle stability

Rotor angle instability, if not corrected in time, may cause cascaded load and generator tripping events which will lead to a major blackout. In recent years, the Phasor Measurement Units (PMUs) have been undergoing fast deployment toward a hierarchical Wide-Area Measurement System (WAMS). Wide-area early warning systems for rotor angle instability are being developed. This paper proposes an online monitoring scheme for rotor angle stability based on PMU data. A loss of synchronism is predicted by Lyapunov Exponents. The relationship between rotor angle stability and the Maximal Lyapunov Exponent (MLE) is established. A computationally efficient algorithm for MLE calculation is developed for on-line applications. Simulation results on a 200-bus model are used to validate the effectiveness of the proposed method.