In order to simulate the transient dynamics of a power system with large wind farms， various mathematic models of the wind turbines are proposed in literatures. In this work， the overall structure for the constant speed constant frequency wind turbines， doubly-fed wind turbines and direct-driven wind turbines is presented. The transient models for the aero dynamics， drive train， generators， electronic converters， and the control and protection system of wind turbines are reviewed. The prospective applications of these models to the grid integrations of wind farms are also discussed.