Research on a Multiport Parallel Type Hybrid Circuit Breaker for HVDC Grids: Modeling and Design

This paper proposes a star type multiport hybrid circuit breaker (Star-HCB) topology for protection of multi-terminal DC transmission. Reliability and stability of high voltage DC (HVDC) grids are determined by their capabilities to withstand DC-side faults. In order to maintain reliability of HVDC grids, both ends of each line should be equipped with hybrid circuit breakers (HCB). This method will increase expenditure of the HVDC, especially the meshed topology. The n-port Star-HCB consists of ultra-fast mechanical disconnectors, load current switch and only one transferring branch which is formed by improved half-bridge sub-module. Compared with existing traditional hybrid circuit breakers and other multi-port hybrid circuit breakers, the proposed topology can realize the same short-circuit blocking goal using fewer components. Detailed mathematical transient process calculation and time-domain simulation of the proposed Star-HCB are given to verify its superiority.