Study on transient stability of grid-connected large scale wind power system

Since the penetration of wind power in electric power supply is increasing greatly, it is urgent to study the impact of wind power on the transient stability of electric power system. In this paper, a model for a simple electric power system with a large wind power plant is constructed, in which, a wind power plant which consists of 6 Doubly Fed Induction Generator (DFIG) transmits power to the system through two stages´ transformation. The studies include examining the transient stability of the power plant in serious system fault under two operation strategies, i.e. fixed power factor operation and fixed voltage operation. The transient stability studies illustrate the reactive power control of DFIG could help maintain the voltage at the wind power plant during system voltage sag. However, once the DC voltage of DFIG reaches its limit, it is impossible for wind power plant to produce reactive for maintaining the voltage since the plant has to disconnect with the grid for purpose of protecting the wind turbines.