Event-Triggered robust control scheme for sub-synchronous resonance mitigation in DFIG-based WECS

Abstract

Series compensation is an economically feasible solution for facilitating the integration of high levels of wind energy sources into the grid. However, high levels of series compensation in transmission lines typically results in sub-synchronous resonance (SSR) in doubly-fed-induction-generator (DFIG)-based wind energy conversion systems (WECS). The introduction of negative equivalent resistance due to negative SSR slip results in self-sustaining oscillating instability and potentially loss of stability of the whole system. This paper proposes an event-triggered sliding mode control (ETSMC)-based control approach for the effective damping of sub-synchronous resonance. The ETSMC control is designed for the rotor side converter of the DFIG, and a phase compensator unit is augmented with the ETSMC control to enhance its efficacy in mitigating specific unstable mode. The proposed control approach is validated using a DFIG-based WECS in IEEE first benchmark model. The results prove the high efficacy of the control approach in mitigating SSR and ensuring system’s fast recovery. In addition to the attributes of the SMC approach, reliance on an event triggering mechanism leads to only seldom control updates, thereby solving the problem of requirement of high communication bandwidth and computational power.