Short-term voltage instability detections of wind generators using synchrophasors

The short-term voltage instability of induction generators (IGs) is the phenomenon of the unstable high slip when the output power exceeds its maximum power transfer. As the penetration of renewable energy distributed source is increasing, the voltage stability issue of large-scale power system with the intermittent source will become increasing important. As severe voltage sags due to a fault in the network, reactive support is greatly reduced and the IG tends to over-accelerate. After voltage recovery, the rotor speed of the IG may be so high that it does not return to the pre-fault equilibrium point. In this paper, the short-term voltage instability of a bulk power grid connected with IGs will be detected by synchrophasor measurement approaches. First, by extending modified coupled single-port models derived from Thevenin equivalent circuits of the bulk power grid with multiple IGs, a synchrophasors-based voltage stability indicator is developed for fast detecting the instability of IGs. Simulation experiments on the IEEE 14-bus system have been conducted to validate the feasibility and the accuracy of the proposed method.