Protection of Dual-Active-Bridge Converters Against Underdamped Surge Current by Current Limiting Reactor

The dual-active-bridge (DAB) DC-DC converter is one of the key components in the medium-voltage DC (MVDC) power distribution system. However, the behavior of the DAB converter in DC fault conditions and the corresponding protection method still need to be investigated. This paper first analyses the influence of external short circuit faults on the stress of DAB components. Among all the investigated fault types, the pole-to-pole and pole-to-ground faults with underdamped system parameters are the critical situations regarding the underdamped surge current through DABs. Then, the effect of the DC reactors in mitigating the fault impact on DABs is analytically presented. The conclusions are validated with simulation results.