Flexible Control Strategy of Energy Router for Integration of Local Area Energy Networks with Diverse Services Provision Capability

As a promising solution to integrate increasing distributed energy resources (DERs), large-scale Microgrids (MGs) will be connected to the distribution system. The smart energy router (ER), which can interface the medium voltage (MV) utility grid and the low voltage (LV) ac and dc distribution grids composed of multiple MGs to form a hybrid AC/DC local area energy networks (E-LANs), can provide high flexible and efficient grid-connected integration, power management and ancillary services for both E-LANs and utility grid. In this study, a flexible control strategy is proposed for the ER to realize simultaneous power flow management, frequency/dc voltage regulation and inertia/damping support for the ER-fed system and the utility grid. The control strategy includes: 1) a modified virtual synchronization generator (VSG) control strategy for the MV and LV DC/AC converters; 2) a mode-adaptive differential droop control used for the LVAC grid side DC-AC converter; 3) a frequency-dc voltage droop control used for utility grid side DC-AC converter; 4) a ratio-based LV dc voltage control used for the DC-DC converter. The proposed method facilitates high penetration of DERs, efficient operation and diversified ancillary services of E-LANs. Simulation results are presented to verify the effectiveness of the proposed method.