Power quality and transient stability improvement of wind farm with fixed-speed induction generators using a STATCOM

This paper investigates the use of a static synchronous compensator (STATCOM) to mitigate the voltage fluctuations and improve fault ride-through capability of wind farm with fixed speed induction generators. In order to assure STATCOM of running safely and reliably in both normal and faulty conditions, a novel control strategy which combines negative-sequence voltage feed-forward control with conventional vector control is proposed to make the negative sequence current of STATCOM zero and effectively suppress STATCOM overcurrent. The positive-sequence and negative-sequence components of the voltage at point of common coupling (PCC) are obtained quickly and accurately by the specially designed double synchronous reference frame phase locked loop (DSRF PLL). The simulation results show that the STATCOM not only significantly improves the power quality, but also enhances fault ride-through capability of wind farm. It is also concluded from the simulation results that the proposed control strategy can effectively suppress STATCOM overcurrent and guarantee that STATCOM can operate safely even in abnormal conditions.