A multi-layer control scheme for microgrid energy management

Due to the widespread diffusion of renewables, the energy management and control of microgrids with non-dispatchable generation units, storage systems, and uncontrollable loads is becoming a topic of paramount interest. This problem is made complex by the need to consider both the continuous dynamics of generators and loads, and a number of logic constraints representing the feasible operating conditions of the devices, such as latency times or charge/discharge constraints. A promising solution, already proposed in various papers, is to resort to hybrid modeling and optimization; however, this leads to very large and intractable mixed integer optimization problems when the number of devices increases. For these reasons, in this paper a multilayer control scheme of microgrids is proposed: the higher layer defines the daily energy exchange with the main network based on a simplified model of the microgrid where dispatchable devices with similar characteristics are organized in clusters. The intermediate, or supervisory, layer allocates the energy requests among the units of each cluster. Finally, the lower layer is made by local controllers of the units. Simulation results are reported to witness the potentialities of this approach.