A Novel Multiport Hybrid DCCB Employing an LC Resonant Circuit for Enhanced Functionality

Multiport hybrid DC circuit breakers (M-HCBs) are considered a suitable solution for protecting multiterminal direct current (MTDC) grids, as the expensive main breaker (MB) is shared among adjacent lines connected to a common bus. However, MBs in most M-HCBs still utilize expensive fully controlled semiconductor devices. In this paper, a novel thyristor-based multi-port HCB (T-MHCB) is proposed to solve this issue, and it has several other advantages. First, the fully controlled semiconductor devices in the MB are replaced with thyristors to inherit some advantages of thyristors. Second, an LC resonant circuit is employed in the proposed T-MHCB to turn OFF the thyristor in MB and avoid the overvoltage problem during the reverse recovery process (RRP). Third, through the LC resonant circuit, the capacitor can be restored to its initial state after the first current breaking process. As a result, the fast-reclosing protection function is provided with no need for additional power supply. Fourth, simple operation sequences reduce the control complexity and enhance its reliability. The topology introduction, operation principles, mathematical analysis, parameter design guidelines, simulation results, experimental results, and comparison study of the proposed T-MHCB are all presented.