Dual-Objective Control Using an SMC-Based CW Current Controller for Cascaded Brushless Doubly Fed Induction Generator

Abstract

This article proposes a dual-objective control method using a sliding-mode control (SMC)-based control winding (CW) current controller for cascaded brushless doubly fed induction generator (CBDFIG), where the smooth grid synchronization and flexible grid-connected power regulation are achieved with the same CW current controller. A so-called virtual grid flux method is introduced to obtain the CW current reference value for the grid synchronization. In addition, according to the relationship between the power winding (PW) power and CW current, a novel direct power control method is proposed for CBDFIG. Furthermore, a unified form of the CW current references is investigated to achieve the dual-objective control for CBDFIG, where no mode switching operation is required and constant switching frequency can be achieved in both the control processes with space vector pulsewidth modulation. The proposed control method shows a strong robustness against the grid voltage disturbances, which is necessarily required in both the grid synchronization and grid-connected power regulation. The simulation and experiments are conducted to validate the effectiveness of the proposed control method.