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Installations of renewable energies, which were promoted in order to solve energy and environmental problems, have been gaining in importance and accelerating. On the other hand, renewable energies have large output fluctuations and it is concerned about negative influences on voltage and frequency control of the utility grid. One of the possible solutions for the situation, new concepts of distribution network, such as "smart grid", which control generations, energy storages and load facilities connected by communication networks in the whole system, are proposed and verification researches are being executed both domestically and abroad. Power electronics (PE) technology is one of the key technologies for such advanced distribution networks. Under such circumstances, functions expected for PE to solve forecasted problems on distribution networks, technical trends of both PE equipment and elemental technology to realize those functions, functional analysis and design methods for PE equipment in distribution networks have been investigated. Investigation results are sorted and described in this technical report from viewpoints below: (1) elemental technologies and practical application, (2) problems on distribution networks with massive renewable energies, (3) design and analysis technologies, (4) PE equipment applied to distribution networks, (5) energy storage system, and (6) renewable energy system. |