Fault Ride Through for a DC Ring Bus Microgrid

DC microgrid is gaining more prominence due to the development of renewable resources that generate DC output and also due to the increasing use of DC in end-user equipments. Also with DC system, connection of backup energy storage and small size generation is easier to realize. For any system, disconnecting a part of the system during temporary faults is uneconomical and might lead to network instabilities. To overcome this, the system must possess Fault Ride Through (FRT) capability. FRT is the ability of the system to remain connected during faults. In this paper, FRT for DC ring bus micro-grid system is achieved for temporary faults. After the occurrence of a fault, the system will ride through the fault until a predefined time period is exceeded. When the predefined time period is exceeded, the system classifies the fault as a permanent fault and the system is isolated. The FRT is achieved by supplying a limited amount of current to the fault using Fault Current Limiters (FCL) working with the proposed algorithm.