Dual Synchronous Rotating Frame Current Control of Brushless Doubly Fed Induction Generator Under Unbalanced Network

摘要

This article investigates the modeling and control of brushless doubly fed induction generator (BDFIG) under an unbalanced network. The system behavior of BDFIG under the unbalanced grid voltage is analyzed. The control strategies and different control targets of BDFIG in balanced and unbalanced networks are discussed. In order to achieve control targets, a current control strategy consisting of a primary controller and a secondary controller for the control winding is proposed. The primary controller is implemented in the positive-sequence synchronous rotating frame (SRF) to ensure the dynamic response of the system without sequence components separation, whereas the secondary controller is implemented in the negative-sequence SRF to control the negative-sequence current component only. A feedforward compensation for the negative-sequence current control is used to mitigate the sequence components separation influence on the dynamic response of the secondary controller. Experimental results demonstrate the effectiveness of the control strategy in suppressing the power and current oscillation of a BDFIG system under the unbalanced network.