Development and Testing of EHV Mechanical DC Circuit Breaker

The paper presents recent development progress of a mechanical EHV DC circuit breaker with current injection scheme. An EHV level DC circuit breaker composes of multi-break HV vacuum interrupters, a current injection circuit and a metal oxide surge arrester (MOSA) energy absorption unit. The interrupting and energy dissipating performance of HVDC circuit breakers based on current injection scheme were demonstrated at DNV-GL/KEMA laboratory supported by the PROMOTioN projects, funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 691714. A test circuit of DC current interruption uses AC short-circuit generators operated at reduced power frequency, which is capable of providing the stresses evaluated from various DC fault conditions with a simple multi-terminal HVDC grid [1]-[6]. Moreover, a prototype of mechanical HVDC circuit-breaker using a couple of 100 kV vacuum interrupter units was tested in our high power laboratory to demonstrate DC current interruption performance at different current magnitudes ranging from 2 kA to 16 kA with both directions of positive and negative DC currents by creating a current zero immediately after contact separation. The MOSA energy absorption units also showed successfully energy dissipation performance up to 4 MJ with a parallel column arrangement. It will also be demonstrated in PROMOTioN project. The paper will describe the performance and recent development progress in detail.