Topology and performance analysis of hybrid DC circuit breaker Based on Cascaded Insulated Gate Bipolar Translator full bridge submodules

Voltage Source Converter based High Voltage Direct Current (VSC-HVDC) transmission system is an important equipment for building smart power grid, as well as an important support for offshore wind power, isolated island power supply and grid integration of photovoltaic power generation. As a key equipment in VSC-HVDC, DC circuit breaker has attracted more and more attention. With the analysis of existing current DC circuit breaker, this paper proposed a technical solution of the hybrid DC circuit breaker based on cascaded Insulated Gate Bipolar Translator (IGBT) full bridge sub modules, introduced the topology of breaking principle, deduced the parameter design method of each component of circuit breaker, and analyzed the influence of several factors such as the number of cascaded modules of IGBT full bridge on the breaking performance of circuit breaker. In this solution, in normal flow state, the main branch with low on-state loss is composed of fast mechanical switch and fewer semiconductor devices. When the current is broken off, the current is transferred to the transfer branch through the cooperation of the main branch and the transfer branch semiconductor device. Then the capacitor is charged by the system voltage in order to achieve second transfer. Finally, the system energy is absorbed and dissipated by the energy dissipation branch. The technical solution achieved the fast break ability with short-circuit current peak value of 15kA under DC voltage of 10kV, and the breaking time is less than 3ms. The DC circuit breaker solution: 1) Adopt modular cascade design with good expansibility. 2) Adopt Bridge structure which can realize two-way breaking, and there is no need to adjust trigger time and device parameters for different short-circuit current. 3) Low on-state loss, externally manifested as low impedance. In summary, the proposed breaking solution of hybrid DC circuit breaker can quickly break off short-circuit current. It is one of the effective solutions for the future development of networking VSC-HVDC distribution system.