Study on the mechanism of transient voltage stability of wind power with power electronic interface

Voltage stability is an important issue to be considered in power system with large scale wind power integration. The mechanism of transient voltage instability induced by wind power is studied. A variable speed wind turbine can control the power rapidly and flexibly with power electronic convertors. The fast dynamics related to power electronic control transients can be neglected, and the wind power is simplified to static power injection model in electromechanical transients. The wind power is modelled with power balance algebraic equations, and the system dynamic equations are differential algebraic equations. The trajectory encountering a singular point corresponds to transient voltage instability of the system, and at this point the power balance equations of wind power become insoluble. Simulation results validate the mechanism, and reveal the variation of instability mode of a wind-thermal-bundled sending system. As the proportion of wind power increases, the instability mode of the system changes from rotor angle instability dominated by synchronous generator to voltage instability dominated by wind power.