Power Management for Islanded Hybrid AC/DC Microgrid With Low-bandwidth Communication

Poor power management of bidirectional interlinking converter (BIC) and sub-grids in a hybrid AC/DC microgrid can lead to a heavy or light load state of some distributed energy resources (DERs), and large deviations of AC bus voltage/frequency and DC bus voltage. This study proposes a distributed power management strategy based on the concept of coordination factors for hybrid microgrids to achieve accurate active power sharing among all AC/DC DERs (instead of the same within one sub-grid), reactive power sharing among AC DERs, and AC voltage/frequency and DC voltage restorations. Power management within a sub-grid is achieved by following the leader DER with the maximum coordination factor. Meanwhile, the BIC can establish a dynamic connection among all DERs by tracking the leaders of each sub-grid to realize power management between sub-grids. Compared to conventional methods, the proposed method can achieve accurate power sharing and voltage/frequency restorations simultaneously. Additionally, communication data and bandwidth can be significantly reduced. Finally, hardware-in-loop experiments are also performed to prove the feasibility of the proposed strategy, even during communication latency or failure.