Cyber-physical aspects of hierarchical control for co-multi-microgrids in the energy Internet

In this paper, the problem of hierarchical control for coordinating multiple ac microgrids (MG) in the Energy Internet is studied. The proposed hierarchical cooperative control (HCC) scheme consists of distributed tertiary control (DTC), distributed secondary control (DSC) and distributed primary control (DPC). Specially, the DTC level controllers are in charge to achieve the active and reactive powers autonomously sharing among ac co-multi-microgrids (CMMG) for minimizing power fluctuations. The DSC and DPC level controllers are responsible for managing the voltage/frequency and power sharing of distributed energy resources (DERs) within an ac microgrid. Two fully distributed communication networks are employed by DTC level and DSC level controllers to achieve information exchanges among microgrids and DERs, respectively. Each microgrid and DER unit only requires the local voltage and current measurement from its own and some nearest neighbors (but not all) for the tertiary control and secondary control using low-bandwidth communication links, respectively. The time-scale property of communication networks for DTC and DSC is induced, which is vital important and precondition for the stability of the whole system. The effectiveness of the proposed control methodology is verified by the simulation of an ac co-multi-microgrids in MATLAB/SimPowerSystems.