Simplified analytical modeling and experimental validation of diode bridge rectifier operation during rail-to-rail short-circuit faults in synchronous generator-fed DC distribution systems

Advancements in power electronics are making it feasible to build high power DC distribution systems. Their power level could reach significant peaks (tens of MW), as in shipboard DC power systems. Such a high power requires high voltage levels to be delivered, which in turn leads to high short-circuits currents. As a result, the design of system protections needs to be carefully performed. Moreover, DC microgrids often include island operation mode, which means lacking a connection to a constant-voltage point of delivery. In this case, the power supply can be provided by different sources, including rectified synchronous generators. In the latter case, it is necessary to consider the generator's internal dynamics during short-circuit transients in order to correctly design protections. In this paper, two simplified models to evaluate DC short-circuit currents are proposed. These are validated in a simplified case study, comparing both of them with the results of a SimPowerSystem® simulation, and finally validated through an experimental set up using a DC testbed built accordingly.