Stability mechanism and emergency control of power system with wind power integration

In power system electromechanical transients, wind power (WP) with power electronic interfaces is more capable of controlling active power compared to synchronous generators (SGs), but less capable of controlling voltage. WP is beneficial to transient rotor angle stability because it improves the deceleration of SG, but it is detrimental to transient voltage stability. A mechanism of WP inducing voltage instability is studied. The fast dynamics related to power electronic control transients can be neglected, and the WP is simplified to static power injection model in electromechanical transients. The WP is modelled with power balance algebraic equations, and the system dynamic equations are differential algebraic equations (DAEs). The trajectory encountering a singular point of the DAE corresponds to transient voltage instability in the system. The power balance equation of the WP becomes unsolvable at the point. Simulation results validate the mechanism, and reveal the variation of instability mode of a wind-thermal-bundled sending system. When the proportion of WP in the system increases, the dominant stability problem changes from rotor angle stability to voltage stability, and the stability of the system first gets better then gets worse. An emergency control strategy against the transient voltage instability induced by WP is proposed. WP is shed to shift the singular surface and avoid encountering singular points. An approach to select the most effective locations for WP shedding is proposed.