Unified DC-Link Current Control for Low-Voltage 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 (WECSs). Among all, low-voltage ride-through has been enforced in the field, which is one of the major challenges for WECS. It is necessary to design an integrated controller to protect the converter from overvoltage/overcurrent and to support the grid voltage during faults and recoveries. In this paper, a unified dc-link current control scheme for current-source-converter-based WECS is proposed. The controllers for generator- and grid-side converters are coordinated to provide fault ride-through capability. In normal operations, the proposed control scheme can also smooth the real power flow while keeping the fast dynamic performance of the dc-link current control. Simulation and experimental results are provided to verify the proposed control scheme.