A novel real-time transient stability prediction method based on post-disturbance voltage trajectories

With the wide application of phasor measurement units (PMU) and wide area measurement system (WAMS) in power system, the real time detection and emergency control of power system transient instability based on the wide-area measurements has brought wide attention. This paper presents a novel technique for predicting transient stability status of a power system following a large disturbance. The synchronously measured samples of the fundamental frequency voltage magnitudes are used to detect the stability. A stability criterion based on the volt-second integration of post-disturbance voltage trajectory is proposed for detecting the transient instability. The drop rate of voltage magnitude after clearing the fault is embedded into the proposed criterion since it indicates the severity of disturbance in some extent. There are two integration termination criteria for fast prediction. Compare with traditional transient stability prediction methods, in which the post-fault rotor angle and angular velocity samples are used to produce the instability criteria, the proposed method improves the reliability and rapidity of transient stability detection especially for the multiple swing instability cases. Studies with both IEEE 39 test system and China Sothern Power Grid indicates that the proposed method is effective.