An Improved Control Method for Standalone Brushless Doubly Fed Induction Generator Under Unbalanced and Nonlinear Loads Using Dual-Resonant Controller

The brushless doubly fed induction generator in the standalone mode is sensitive to unusual working situations, particularly unbalanced and nonlinear loads. The unbalanced and nonlinear loads can cause significant unbalance and distortion for voltage and current of the power winding (PW). In PW voltage under nonlinear and unbalanced loads, the component of negative sequence represents the unbalance influence, and the fifth and seventh harmonics components represent the nonlinear influence. To address these issues, the dual-resonant controller is employed to reduce the unbalance and nonlinear influences of PW voltage via generating the reference command of control winding voltage, which compensate the negative-sequence component and fifth and seventh harmonic components of PW voltage through the machine-side converter. The experimental and simulation tests are applied to check the effectiveness of the proposed strategy.