Robust Nonlinear Controller Design for Damping of Sub-Synchronous Control Interaction in DFIG-Based Wind Farms

A robust controller taking advantage of feedback linearization control (FLC) and sliding mode control (SMC) is proposed with an objective of mitigating the sub-synchronous control interaction (SSCI) in series-compensated doubly fed induction generator (DFIG)-based wind farms (WFs). FLC method is employed to obtain the reduced-order model of the studied system and, hence, smaller computation burden to controller design. Moreover, unlike linear control methods, FLC enables the controlled system to be independent of the pre-specified operations, which is suitable for highly nonlinear DFIG-based WFs. Considering that the FLC can be sensitive to parameter uncertainties, SMC is combined with the FLC to improve the robustness of the system. To evaluate the performance of the proposed feedback-linearized sliding mode controller (FLSMC) as compared to the conventional sub-synchronous resonance damping controller, the electromagnetic transient simulation and small-signal stability analysis are carried out. The designed FLSMC is observed to demonstrate the effectiveness in SSCI mitigation and robustness against the parameter perturbation at varied operating conditions. The experimental tests are performed to validate the veracity of the simulation results.