A Unified DC Link Current Control Scheme for Grid Fault Ride-Through in Current Source Converter Based Wind Energy Conversion Systems

The increased penetration of wind power into utility grid brings challenges to power converter design in wind energy conversion systems (WECS). Among all, low-voltage ride-through has been enforced in the field, which is a major challenge for WECS. It is necessary to provide an integrated controller to protect the converter from over-voltage/over-current and to support the grid voltage during fault and recovery. In this paper, a unified dc link current control scheme for current source converter (CSC) based WECS is proposed. The controllers for generator-side and grid-side converters are coordinated to provide grid fault ride-through capability. In normal operation, the proposed control scheme can also smooth the real power flow while keeping the fast dynamic performance of the dc link current control. Simulation waveforms and experimental results are provided to verify the proposed control scheme.