Distributed unified control for global economic operation and resilience reinforcement of hybrid AC-DC microgrids

Abstract

The paralleled BILCs of the HMG provide a flexible and reliable power interaction way between ac and dc subgrids with high power density. A DUC is proposed for BILCs to achieve both resilience reinforcement and global economic operation of the HMG. For DGs, the fac-λac and vdc-λdc economic droop controls are employed for ac DGs and dc DGs to decrease the individual subgrid's generation expense by equaling DGs' incremental expenses. For BILCs, the normalized ac subgrid's frequency and dc subgrid's voltage are coordinated to achieve the economic power interaction, which further decreases the total generation expense. Besides economic operation, the proposed DUC is capable of adopting different microgrid operation modes into a unified control structure without any mode switching. Paralleled BILCs are managed to reinforce the system resilience by supporting the dc voltage or ac voltage once all dc or ac DGs fail. In addition, the proposed DUC enables BILCs with plug-and-play characteristics, resistance to the maximum acceptable communication delay, and the communication disruption robustness. The corresponding hardware-in-the-loop results verify the effectiveness of the proposed control strategy.