A robust damping controller for DFIG based on variable-gain sliding mode and Kalman filter disturbance observer

This paper proposes a sliding mode based inter-area oscillation damping control strategy for the Doubly Fed Induction Generator (DFIG) to enhance the stability of interconnected power systems. The synthesized damping controller is designed based on the variable-gain super-twisting algorithm to deal with the inherent nonlinear behavior in the DFIG and the power system. A Derivative-free nonlinear Kalman Filter is also developed as a disturbance estimator to accurately estimate the disturbance terms in the represented system. Such estimated results make the gains of super-twisting algorithm more efficient. The proposed controller is insensitive to the presence of unmolded system dynamics and the external disturbances acting on the system, and has a fast response speed and robustness with respect to the power system uncertainties. The stability property of the proposed damping controller is proved via the Lyapunov method, and its performance has been verified through numerical simulations considering detailed system model, external disturbances and operation point uncertainty.