PMU based voltage stability analysis for transmission corridors

A new equivalent model based on phaser measurement unit (PMU) is proposed to analyze and predict the voltage stability of a transmission corridor. This equivalent model retains all transmission lines in a transmission corridor, which is more detailed and accurate than traditional Thevenin equivalent model widely used. To estimate parameters of the proposed model, Newton method or the least square estimation method is adopted by using multiple continuous samples of PMU measurements. Based on the new model, an actual load increase direction is estimated real-time with PMU measurements, along which the load margin is calculated. The load margin is equal to the available transfer capacity (ATC) of the transmission corridor, and is used as a voltage stability index. The proposed model and algorithm have been tested on the IEEE 9-bus system. Compared with traditional Thevenin equivalent method, the proposed algorithm is more accurate and effective, and with acceptable computation burden.