Comparison of Multiphase Active and Passive Rectifiers in Wind Turbine

This study proposes a comparison of the operation of active and passive multiphase rectifiers in an all-DC wind generation system. The all-DC system includes a hybrid generator interfaced to the medium voltage DC grid (MVDC) via a rectifier stage whose output is connected to a DC-DC converter that steps up the voltage to a fixed high voltage DC (HVDC) for transmission. System operation is discussed by considering an active or passive rectifier as an AC-DC converter. Using a passive rectifier, control of the field current of the hybrid generator and DC-DC controller allows wind turbines to maintain their desired power via MPPT while enabling a variable voltage MVDC grid operation, however, by adjusting an active rectifier, the power control is shifted to the converter and the DC-DC converter will maintain a fixed MVDC voltage without a need to variable MVDC voltage. Simulation results are presented to confirm the proposed control strategy for each system.