Collaborative Control of DFIG System During Network Unbalance Using Reduced-Order Generalized Integrators

The paper presents a collaborate control for the rotor-side converter (RSC) and grid-side converter (GSC) of a doubly fed induction generator (DFIG) generation system during network unbalance. In this study, the RSC is controlled to reduce the torque ripples, and three selectable control targets for the GSC, i.e., balanced total currents, and constant total active or reactive power into the grid from the overall system are identified to reduce the impacts of the negative-sequence voltage on the DFIG system performance. A reduced-order generalized integrator is employed, which is implemented in the positive synchronous reference frame. Based on the math model, the impacts of the limited dc voltage, as well as the rejection capability on negative-sequence voltage of the proposed control strategy, have been investigated. Finally, the simulation and experimental results are provided to demonstrate the effectiveness of the proposed collaborative control strategy.