Supplementary Damping Control of STATCOM to Mitigate SSCI

In this paper, a supplementary damping control scheme for static synchronous compensator (STATCOM) is proposed to stabilize the oscillation caused by subsynchronous control interactions (SSCI) phenomenon in a series-compensated doubly fed induction generator (DFIG) based wind farm. Various system conditions determine the oscillation frequency, which is usually different for different SSCI events. Therefore, it is a great challenge to design an efficient and reliable damping controller to stabilize the SSCI. A damping controller based on combination of filters, gain, and phase-shifts is designed for STATCOM controller. With the proposed scheme, the STATCOM is able to provide positive damping for a wide range of system conditions, and thus covering a wide band of oscillation frequencies. The performance of the proposed scheme is validated on an aggregated model of an actual wind power system using Simulink environment. The time-domain simulations have demonstrated the effectiveness of the proposed scheme for mitigating the SSCI at various oscillation frequencies.