Fast acting DC circuit breaker for HVDC transmission line based on DC/DC chopper

In this paper, two fast acting dc circuit breakers are investigated to interrupt the short-circuit faults in HVDC transmission lines. These circuit breakers are realized using dc/dc choppers which can also perform step-up and/or step-down functions. Compared to the existing topologies, the number of active switches in the proposed configurations are minimized to achieve lower initial cost and higher conversion efficiency. A double closed-loop controller based on PI regulators is designed to regulate the inductor current and output voltage of the converters. An auxiliary controller is also proposed to ensure proper shut-down of the chopper in the event of short-circuit faults. The simulation and experimental results are presented to validate the proposed converter topologies and control scheme.