Equal power sharing in islanded AC/DC hybrid microgrids

AC/DC hybrid microgrid is a promising architecture that allows for hosting energy resources and modern loads from AC and DC types; and in turn, it reduces the number of conversion stages among other technical and economical benefits. Consequently, power distribution planners started to investigate the possibility of hybridizing the existing AC grids and designing new AC/DC hybrid clusters referred to as microgrids as a step towards the envisioned smart grid with AC/DC technologies and 'plug-and-play' feature. Nevertheless, while being islanded, AC/DC hybrid microgrids bring operational challenges to the system operation such as coordination among the distributed resources in both AC/DC subgrids, control and management of the power transfer through the interlinking converters, droop control of inverter-based distributed energy resources, and accurate power sharing. This paper looks closely at the problem of active and reactive power sharing in islanded droop-based AC/DC hybrid microgrids and proposes a unified power sharing scheme that is able to simultaneously ensure precise power sharing in both AC and DC subgrids. Test results demonstrate the capability of the proposed scheme in achieving exact power sharing not only among the energy resources in proportion to their ratings but also among the interlinking converters.