Fault Current Limiting Power Converters for Protection of DC Microgrids

This paper presents a review of different topologies of power converters that are suitable for interfacing power sources to the dc distribution bus of a microgrid. Despite the high controllability of electronic power converters, not all converter topologies behave the same during a bus fault condition. Some topologies are able to limit fault currents, can participate in the protection scheme and can decrease the risk of catastrophic damage. Other topologies lose controllability in a situation of fault on the distribution bus and need to be protected against permanent damage by fast fuses, circuit breaker and fault current limiters. Power converters, such as back-to-back VSCs, buck-type isolated converters, Full Bridge MMCs and similar, can be controlled to limit the fault currents, coordinated with protection devices, minimize the risk of catastrophic damage of the distribution system and increase the resilience and survivability of the microgrid.