The Post-fault DC Chopper Activation in VSC-HVDC Systems for Offshore Wind Transmission

In this paper, two kinds of post-fault DC Chopper activation in VSC-HVDC systems for offshore wind transmission are reported. This activation is unexpected in DC Chopper designing and it can be explained by the lack of rapidity of VSC inverter's control performance. To avoid this post-fault activation, the technical solutions such as faster protection, greater gains of controller and better var compensation are also put forward in this paper. Finally, this unexpected DC Chopper activation and countermeasures are demonstrated and verified in numerical illustrations.