Power Decoupling Control for Wind Turbine Converter Based on Series-Connected Modular Multilevel Converter

A power decoupling control for wind turbine converter based on series-connected modular multilevel converter (SCMMC) and open-winding permanent magnetic synchronous generator (OW-PMSG) is proposed in this paper. The phase dc links of the SCMMC are series connected and the windings of the OW-PMSG are independent, which is different from conventional MMC. To improve the robustness of the system under imbalanced power disturbance, an ac power decoupling control is proposed with perfect power independent control of the three phase power and phase dc-link voltages. Besides, multi-frequency-bandwidth proportional-resonant (MFBPR) controller in the abc stationary frame without coordinates transformation is presented, which simplifies the control of the SCMMC. The accurate current control is based on the MFBPR controller and it is easy to improve the quality of the current with this controller. The proposed power decoupling control is verified through simulation and a 3 kW laboratory prototype.