State Dependent Riccati Equation Based Rotor-Side Converter Control for Doubly Fed Wind Generator

This paper proposes a rotor-side converter (RSC) control of doubly fed induction generator (DFIG) through state-dependent Riccati equation (SDRE) approach to enhance the low voltage ride through (LVRT) ability. In order to guarantee the stability of the DFIG-based wind farm under external disturbances, a robust input-to-state stability (ISS)-based controller is presented in cooperation with the SDRE approach. The robust ISS controller is proved to be able to stabilize the wind generation system, while the system dynamics are not guaranteed to be of high performance. By parameterizing the robust ISS controller, the SDRE approach is used to provide guidance for the selection of ISS control parameters. Due to design flexibility, the SDRE control has the ability to enhance dynamic performances of wind generation system through optimizing the state-dependent coefficients. Time-domain simulations are carried out to verify the effectiveness of the proposed control approach. Compared with the conventional PI controller, exact linearization-based nonlinear controller, and robust ISS controller, the proposed SDRE-based RSC control has the ability to optimize the dynamics of the wind generation system during and after faults, and has better LVRT performance.