Fundamental characteristics of DC microgrid for residential houses with cogeneration system in each house

DC microgrid is a novel power system using dc distribution in order to provide a super high quality power. This system is suitable for dc output type distributed generations and energy storages. The dc power can be converted to the proper ac or dc voltages for the consumers by converters placed near loads, and these converters do not require transformers. This distributed scheme of load side converters also contributes to provide the high quality power supplying. In this research, we assumed a dc microgrid applied for residential houses. All houses have a cogeneration system such as gas engine or fuel cell. The outputs of those distributed generations are connected to the dc distribution line, and the power from the generations can be shared among the houses. The hot water from distributed generations are used in each house. We constructed a small scale experimental in our laboratory, and examined the fundamental characteristics of the dc microgrid by the experimental system when it was connected to the bulk power system. Experimental results demonstrated that the system could supply high quality power to the loads stably against sudden load variations, voltage sags of the bulk power system and short circuits of the load.