Autonomous control of interlinking converters in hybrid AC-DC microgrids with energy storages

Abstract

Coexistence of both ac and dc sub-grids in a hybrid microgrid is likely given that modern distributed sources can either be ac or dc. Linking these sub-grids are power converters, whose topological configuration should preferably be not too unconventional to avoid unnecessary compromises in reliability. The desired operating features should therefore be introduced to the interlinking converters through control design with overall system simplicity still preserved for industry relevance. This concern is now addressed here through the development of an appropriate scheme for controlling the interlinking converters, so as to achieve autonomous control for the overall hybrid microgrid. Features achieved include proportional active power sharing among the distributed sources based on their ratings and not placements within the hybrid microgrid, and proper reactive power sharing within the ac sub-grid. These findings are not previously achieved by other existing schemes, which almost always consider only an ac microgrid. The scheme can also be extended to include energy storages within the interlinking converters, as demonstrated through simulation and experiment.