A Hierarchical Control Framework for Islanded Multi-Microgrid Systems

This paper proposes a hierarchical control framework for islanded multi-microgrid (MMG) systems. The proposed framework consists of four levels: 1) the microsource controller, which is droop-based and responsible for output voltage/current regulation and load demand sharing of distributed generators (DGs); 2) the microgrid central controller, which manages DGs within a microgrid to coordinate with each other to follow commands received from the upper level controller; 3) the microgrid interface controller, enabling a microgrid interfaced with others to share load power accurately in a decentralized manner; and 4) the multi-microgrid central controller, which restores the system frequency and the critical bus voltage to their nominal values. Control objectives under this framework are validated using a two-layer power flow model. Transient simulations using PSCAD/EMTDC are performed to validate the dynamic performance of the proposed method.