Application of interphase inductors for parallel generator-side converters in direct-drive wind turbine system

To improve the power rating of direct-drive wind turbine system, this paper proposes the parallel operation of two generator-side converters with interphase inductors. In the paper, the decoupling equivalent circuit and the zero-sequence circulating-current (ZSCC) models are derived. The fundamental mechanism of ZSCC suppression with interphase inductors is illustrated. Then the control strategy of the system is designed in the synchronous rotating coordinates. The ZSCCs are suppressed well and the discrepancy and distortion of currents are overcome. Therefore, the reliability and efficiency of the system are improved. Finally, the parallel generator-side converters with the power rating of 1.5 MW are simulated, which verifies the validity of the above analysis.