Mitigating Subsynchronous Resonance in DFIG-Based Wind Farms Using a Robust Terminal Sliding Mode Controller

In this paper, a robust terminal sliding mode controller (TSMC) is proposed for doubly-fed induction generator (DFIG)-based wind farms to mitigate subsynchronous resonance (SSR) induced by series-compensated transmission lines. Here, the controller governs the rotor-side converter (RSC) of a DFIG, utilizing a new exponential reaching law that is specifically designed for damping the SSR. The controller's robustness against external disturbances is thoroughly evaluated by incorporating them within the dynamic model of the RSC, while considering the impacts of series compensations. The stability of the entire DFIG-based wind farm, including the series compensator, is rigorously analyzed using the Lyapunov stability theory. The performance assessment of the proposed approach in mitigating the SSR is conducted, and results are presented, along with comparisons against a fractional-order SMC (FOSMC).