Multiple Line-to-Ground Fault Characterization and Mitigation in MVDC Shipboard Electrical Systems

Future shipboard electrical systems utilizing zonal Medium Voltage dc (MVdc) distribution, face conflicting design objectives. The system must be simultaneously power dense, cost effective, and survivable. DC zonal distribution with multiple generation sources offers survivability advantages. Shipboard electrical distribution systems can utilize a floating ground design to increase survivability in single line-to-ground (SLG) fault scenarios. However, this could decrease the survivability upon the incidence of a second line-to-ground (LG) fault or during multiple line-to-ground fault (MLG) scenarios. Particularly when it comes to critical loads that are cross-fed from opposite sides of the ship and MLG faults on opposite polarity buses or between ac and dc buses occurring in different zones. This work characterizes the most problematic MLG fault scenarios and analyzes mitigation anpproaches.