Fault ride through of DFIG wind turbines during symmetrical voltage dip with crowbar or stator current feedback solution

Low Voltage Ride Through is an important feature for wind turbine systems to fulfill grid code requirements. In case of wind turbine technologies using doubly fed induction generators the reaction to grid voltage disturbances is sensitive. Hardware or software protection must be implemented to protect the converter from tripping during severe grid voltage faults. In this paper two methods for low voltage ride through of symmetrical grid voltage dips are investigated. As a basis, an analysis of the rotor voltages during grid fault is given. First, the conventional hardware method using a crowbar is introduced. Then the stator current reference feedback solution is presented. Both methods are investigated and compared by simulation results using 2 MW wind turbine system parameters. Measurement results on a 22 kW laboratory DFIG test bench show the effectiveness of the proposed control technique.