Power management for hybrid AC/DC microgrid with multi-mode subgrid based on incremental costs

Abstract

The hybrid AC/DC microgrid is attracting more and more attention, which can accommodate multiple subgrids. So, the flexible power interaction and economical operation in the hybrid AC/DC microgrid are complicated. A power management strategy for hybrid AC/DC microgrid considering multi-mode subgrid and generation cost is proposed in this paper. First, three operational modes for subgrids are defined, which include subgrid power autonomy (SPA), subgrid power sharing (SPS), and subgrid-ESU power coordination (SEPC). With the multi-mode subgrid, greater operating flexibility and less exchanged power can be facilitated among subgrids. Second, event-driven mode switching rules are established. The rules set thresholds for different events to meet different power quality requirements of subgrids. Besides, the virtual incremental costs are introduced for the designed events to avoid mode switching repeatedly. Third, the exchanged power is calculating by equalizing the nominal value of frequencies and voltages. In this way, the incremental costs of subgrids and ESUs can reach equality and reduce the total operating cost. Finally, simulations are carried out to demonstrate the effectiveness and superiority of the proposed power management strategy.