A Novel Dynamic Power Routing Scheme to Maximize Loadability of Islanded Hybrid AC/DC Microgrids Under Unbalanced AC Loading

This paper proposes a novel dynamic power routing (DPR) scheme for hybrid ac/dc microgrids operating in islanded mode, where unlike in grid-connected microgrids, local generation adequacy is crucial for proper system operation. The unbalanced nature of ac distribution networks limits the microgrid loadability in the sense that loads must be shed from heavily loaded phases, even if the connected distributed generators (DGs) have not reached their total three-phase capacity limits. The main challenge is to exploit the available resources by routing the power between the ac subgrid phases, thereby minimizing load shedding. The proposed method utilizes the interlinking converters between the ac and dc sides of hybrid ac/dc microgrids to provide this functionality. A supervisory controller implements a DPR-based optimal power flow (OPF) algorithm to allow full loadability of the islanded network. The formulated OPF problem is solved analytically using an interior point method that has proved to be computationally cost-effective. Many case studies are conducted to address the unbalance problem and to validate the effectiveness of the proposed strategy against conventional methods, which are based solely on optimal DG droop settings.