Recently, various voltage-source or current-source inverter based FACTS devices have been used for flexible power flow control, secure loading, damping of power system oscillation, and even for stabilizing the wind generator. In this chapter, we propose the static synchronous compensator (STATCOM) based on a voltage source converter (VSC) PWM technique to stabilize a grid connected wind turbine generator system (WTGS). The three-level STATCOM topology is considered instead of the two-level STATCOM, as it is suitable for high-voltage application. The well-known cascade control scheme is used as the control strategy of the VSC based STATCOM. A multi-mass shaft model of a wind turbine generator system is also considered because shaft modeling has a big influence on the transient performance of a WTGS. Moreover, it is reported that a STATCOM can reduce the voltage fluctuation significantly in steady state operation under randomly varying wind speed conditions.