A Novel DC Energy Dissipation Topology With Concentrated Dissipation Resistor and Control Method for Offshore Wind VSC-HVDC System

A DC-side energy dissipation device and control method for offshore wind power generation systems have been proposed, which effectively solves the energy imbalance caused by the AC voltage drop at the receiving end. The proposed circuit structure uses IGBT and metal oxide varistor(MOV) to form a switching module, effectively avoiding the overvoltage problem caused by the IGBT series structure during the turn-off process, while significantly reducing the overall equipment volume. The proposed structure connects the energy dissipation resistor with the main circuit through a coupling transformer, which reduces the voltage at both ends of the energy dissipation resistor, thus reducing the cost of high-voltage wall bushings in the system. The proposed DC voltage and energy dissipation resistor current dual-loop control method can flexibly adjust the dissipation power of the energy dissipation arm. When a single switch in the arm fails, the proposed multi-equipment coordinated control method can realize Fault Ride Through(FRT) at the AC side of the receiving end converter(REC). Simulation and experimental results confirm that the proposed hardware structure and control method can safely and stably handle the DC voltage increase caused by the AC voltage drop at the receiving end.