Development of a Thyristor-Assisted Hybrid DC Circuit Breaker for Reduced Cost and Size

The hybrid dc circuit breaker (HCB) is an important piece of equipment for clearing dc faults and maintaining the safe operation of dc grids. The current transition from a mechanical switch to a power electronic switch has always been a crucial issue in HCB, and the existing HCBs generally require dedicated auxiliary commutation devices, which bring additional cost and size. To address the key issue, this letter proposes an improved thyristor-assisted hybrid dc circuit breaker (TA-HCB) solution. A novel thyristor commutation module integrated into the transfer branch not only enables current commutation but also can assist the power electronic switch in withstanding a portion of the static dc voltage during interruption, greatly reducing the volume and cost of the HCB. After a detailed illustration of the operation process and the voltage distribution process, a 3 kV/6 kA prototype experiment was conducted to verify the feasibility of this TA-HCB.