Breakerless Protection for Voltage Source Converter-Based Marine DC Power Supply Systems

DC power supply systems utilising voltage source converters offer several advantages compared with their counterparts in marine low-voltage DC power distribution networks. In case of a two-level voltage source converter fed by a synchronous generator which is widely employed, a solid-state circuit breaker or a high-speed fuse is necessary for the converter protection due to its no fault-handling function and low fault withstand capability. However, the use of the solid-state circuit breaker and the high-speed fuse makes such a DC solution expensive and less reliable, respectively. Hence, this paper proposes a breakerless protection method for the voltage source converter-based marine DC power supply systems. The proposed method consists of an artificial short circuit on AC side (between the generator and the converter) and generator deexcitation. By employing the proposed method, the fault energy passing through the converter can be mitigated by the artificially generated short circuit between them and the current from the generator finally becomes zero by the deexcitation. This method allows for managing the fault energy under the converter and generator withstand capabilities without relying on the conventional breaking devices.