Bridge-Type Integrated Hybrid DC Circuit Breakers

The inclusion of a large number of controllable semiconductor devices in conventional hybrid dc circuit breakers (HCBs) may significantly increase the cost of an HVdc grid protection scheme. In an attempt to reduce this cost, this paper proposes the use of two novel topologies of bridge-type integrated HCBs (BT-ICBs). The two configurations are examined in detail, their operation sequences are established, and a detailed parametric analysis is conducted. The total number of controllable semiconductor devices in a BT-ICB is assessed with the aid of selectivity studies, and a comparison is made when conventional HCB and other ICB topologies are considered. It is shown that the proposed configurations employ 50% to more than 70% less controllable devices compared with conventional HCBs. The proposed BT-ICB topologies are tested in PSCAD/EMTDC using a four-terminal HVdc grid. The simulation results demonstrate the capability and effectiveness of the proposed solutions to isolate different types of dc faults at either a dc line, a converter terminal, or a dc bus.