Impedance Shaping Control for STATCOM to Improve the Stability of Wind Farm Systems

Static synchronous compensator (STATCOM) is able to mitigate the resonance in wind farms by optimizing the controller parameters in a way to shape its impedance. However, doing so may be not always effective due to the limitations in the STATCOM design. Therefore, this paper proposes a STATCOM impedance shaping control scheme to damp the system resonance by adding a voltage-feedforward-based active control path. As the basis, impedance models of the STATCOM considering a general voltage feedforward control are developed. Then, the effect of the STATCOM with the voltage feedforward control on the stability of wind farm systems is analyzed, which leads to the development of the voltage-feedforward-based impedance shaping control. The proposed method can mitigate system resonance, while maintaining the performance of the STATCOM. The effectiveness of the proposed method has been demonstrated on a representative wind farm by simulation.