Nonlinear controller based on state feedback linearization for series-compensated DFIG-based wind power plants to mitigate sub-synchronous control interaction

This paper proposes a nonlinear controller based on state feedback linearization (SFL) method to mitigate sub-synchronous control interaction (SSCI) in series-compensated doubly fed induction generator (DFIG)-based wind power plants (WPPs). To make full use of the converter control of DFIG, the SFL controller is developed for both grid side converter (GSC) and rotor side converter (RSC) through four necessary steps, ie, assessment of the feedback linearizability, coordinate transformation, feedback linearization, and derivation of control laws. The stability of the internal dynamics, which is not transformed into linear autonomous subsystems in the design process of the RSC controller, is ensured by the application of zero-dynamic theory. A 100-MW DFIG-based WPP adapted from the IEEE first benchmark model is utilized to evaluate the effectiveness of the SFL damping controller at different wind speeds and compensation levels, and the capability of the proposed controller in mitigating SSCI is compared with a well-tuned proportional-integral controller and a conventional SSCI damping controller. The superior performance of the SFL controller is demonstrated at varied operating conditions through frequency scanning analysis, eigenvalue analysis, and electromagnetic transient simulation. Moreover, the robust stability of the proposed controller is guaranteed under parameter uncertainties using analysis.