A Robustness-Improved Control Method Based on ST-SMC for Cascaded Brushless Doubly Fed Induction Generator

This article presents a robustness-improved control method combining super-twisting sliding mode control (ST-SMC) based control winding (CW) current controller and PI-based power regulator for cascaded brushless doubly fed induction generator (CBDFIG). To reduce the computation burden of the controller, the strong robustness and the fast dynamic response of the ST-SMC is extremely suitable for the inner CW current loop whose control period is smaller than that in the outer power loop. Therefore, the state-space model of CBDFIG is derived and a robust CW current controller is designed based on the ST-SMC with the stability analyzed. In addition, according to the relationship among the electrical variables of CBDFIG deduced, a PI-based power regulator is designed with the stability analyzed and the parameters selected to achieve a satisfying steady-state performance. Finally, the simulation and experimental results based on a 5-kW prototype CBDFIG demonstrate the effectiveness of the proposed control method.