Hybrid Robust Adaptive Backstepping Sliding Mode Controller Design for Mitigating SSR in Series-Compensated DFIG-Based Wind Generation Systems

This paper proposes a hybrid control scheme where the concept of adaptive backstepping and sliding model control schemes is combined together to suppress the subsynchronous resonance (SSR) in series-compensated wind generation systems with doubly fed induction generators (DFIGs). The rotor- and grid-side converters (i.e., RSC and GSC) are controlled with the proposed control scheme to tackle nonlinearities with the model and provide robustness against external disturbances while eliminating the SSR in a quicker way. In the proposed control framework, the backstepping control scheme ensures the desired tracking of states by considering all nonlinearities in the dynamical model and the adaptation scheme is employed to estimate external disturbances while the sliding mode scheme based on a quick reaching law makes sure that the desired performance is achieved in a faster way. The proposed scheme effectively eliminates the SSR as it is designed by considering the effects of series compensator within the dynamical model. At the same time, the Lyapunov stability theory is used to analyze the overall stability of the series-compensated DFIG-based wind generation system with the proposed scheme. MATLAB/SIMULINK platform is used to simulate the performance of the proposed controller on a series-compensated wind generation system by considering different compensation levels demonstrating the worst case operation under varying wind speed conditions. Simulation results are compared with an existing hybrid controller designed using the feedback linearization and sliding mode control schemes where results under different operating conditions clearly demonstrate the superiority of the proposed scheme in terms of mitigating the SSR in a much faster way.