A Single Machine Equivalent-Based Approach for Online Tracking of Power System Transient Stability

This paper presents a systematic single machine equivalent system based scheme for fast and accurate prediction of impending angular stability using measurements from generator terminals only. In a post-fault scenario, Kalman filter is designed to estimate rotor positions in real-time, based on damper winding observer with measurements gathered from generator terminals. To identify critical machines, short time-ahead prediction of rotor position is made by designing another Kalman filter. A general method is suggested to differentiate between critical and non-critical machines. To further enhance the accuracy of predicted time to instability, an extrapolation algorithm is developed, based on the knowledge of estimated rotor angles and short time-ahead predicted rotor angles. The proposed methods are successfully implemented on WSCC 9-bus, IEEE 39-bus, and NRPG 246-bus test systems.