A Novel DC Chopper With MOV-Based Modular Solid-State Switch and Concentrated Dissipation Resistor for ±400 kV/1100 MW Offshore Wind VSC-HVDC System

A dc chopper (DCC) is one of the key equipment in voltage-sourced converter-based high-voltage dc transmission systems with offshore wind power access. Combining the complementary advantages of concentrated and modular DCCs, a novel DCC with modular solid-state switches and a concentrated resistor (MC-DCC) is proposed. The non-long-term work attribute of the DCC provides opportunities to apply metal oxide varistors in modularizing series solid-state switches, thereby removing the capacitors for voltage balance. A method of designing the MC-DCC is introduced on the basis of the analysis of system requirement. Finally, prototype experiments are conducted to verify the effectiveness of the MC-DCC.