Coordination between supply power converters and contactors for fault protection in multi-terminal MVDC distribution systems

We present a fast and effective method for detecting and isolating faults in multi-terminal medium voltage dc shipboard power distribution systems. This new detection method permits coordination between the power supply converters and a set of bus segmentizing contactors without requiring fast communication between the elements. The power converters go into current-limiting mode as soon they recognize a fault condition and the segmentizing contactors autonomously decide whether or not to open based on local interpretation of time-to-trip curves as functions of apparent circuit resistance. This method allows converters and contactors to use only local measurements when deciding whether or not to trip in order to isolate the faulted section (later fine tuning can rely on communications). Simulation and experimental results show that faults can be isolated within 10 to 20 ms and the system can be re-energized within 40 to 60 ms.