Fault Ride-Through of DFIG-based Wind Farms connected to the Grid through VSC-based HVDC Link

This paper describes two new control ap- proaches for DFIG-based offshore wind farms connected through voltage source converter (VSC) based HVDC link with extended fault ride-through (FRT) capability. These control strategies establish a coordination between the HVDC terminals and the wind turbines, allow safe operation of the wind farm during grid faults and also fulfill the actual grid code requirements. Both introduced FRT methods uti- lize different means for a fast and reliable power reduction in the wind farm to protect the HVDC transmission against overvoltages, which may occur as a result of a power imbal- ance between sending and receiving end during grid faults. This way the costs for a high rated DC chopper can be saved. For evaluation of these approaches detailed simulation mod- els of the HVDC and the wind turbines are presented. The simulations are carried out in MATLAB/Simulink with Sim- PowerSystems Toolbox. The simulation results show an ex- ample of a severe three-phase grid fault, which proves the good performance of the proposed control strategies.