Abstract
“DC Micro-grid" is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc distribution line and converted to required ac or dc voltage by converters placed near loads. The load side converters do not need transformers by choosing proper distributed dc voltage. The spread scheme of converters contributes to provide a high quality power supplying. Even if a short circuit occurs at one load side, it does not effect other loads. In this paper, we propose a configuration of DC micro-grid and control methods of converters for generations and energy storages. Computer simulation results demonstrated the seamless operation during turn-on and turn-off of a distributed generation, the transient of connecting and disconnecting operation with bulk power system, and the stability against a sudden large load variation.
