Multiport Current Injection Hybrid DC Circuit Breaker With Simple Bridge Arm Circuit

Abstract

Multiport hybrid DC circuit breakers (M-HCBs) have been recognized as suitable devices for protecting DC grids. Most M-HCB topologies include load current switch (LCS), leads to inevitable conduction losses as load current may flow through LCS under no-fault conditions. Only a few multiport current-injection HCB (M-C-HCB) topologies have been proposed in previous articles to remove LCS from load current branch, however, additional power supply or complex additional circuit for repetitive capacitor pre-charging is required, resulting in increased system cost and reduced reliability. To overcome the main shortcomings mentioned above, this article proposes a novel M-C-HCB topology, only one capacitor configured with a simple bridge arm (BA) circuit is used to realize the fault current communication process from load current branch to main breaker branch, and external pre-charging solution is required for only once. The load current switches (LCSs) composed of semiconductor devices is removed from the load current branch (LCB) to achieve minimizing the conduction losses. The working principle is introduced in detail and the parameter designs are discussed. A comparison with some traditional M-HCBs and other M-C-HCB solutions is presented to show the efficiency and economic advantage. Finally, the proposed topology is validated with three-terminal HVDC grid simulations and a scale-down experimental prototype.