Experimental validation of DC circuit-breakers for MTDC grid protection

Many High-Voltage Direct-Current (HVDC) circuit-breakers have been proposed for fault management in different HVDC applications e.g. Multi-Terminal HVDC (MTDC) grids. However, studies in the literature mainly focus on the topology design of DC Circuit Breakers (DCCBs). The application issues associated with DCCBs in DC grids need to be investigated. This paper examines the voltage and current characteristics of DCCBs using time-domain simulations and experimental platform. The factors affecting the fault current interrupting performance of the DCCBs are studied. Furthermore, a small-scaled DCCB prototype is designed and deployed in a three-terminal meshed voltage-source-converter based HVDC test-rig. A set of tests against specified dc-side faults in the test-rig are conducted to validate and verify the functions/performances of the DCCBs. Studies show that the parameters of DCCB's, current limiting reactor and surge arrestor will affect the performances of the DCCB. The DCCBs were successfully implemented and tested for dc fault current interruption and isolation in the test platform.