General distributed secondary control for multi-microgrids with both PQ-controlled and droop-controlled distributed generators

A novel general distributed secondary control (DSC) scheme is proposed to implement coordination control for both droop-controlled and active power and reactive power (PQ)-controlled distributed generator (DG)-clusters in multimicrogrids (MMGs), using cluster concept. It not only reduces the steady-state derivation caused by primary droop control, but also brings the whole MMG into a new optimised operation state in the secondary control. The implementation of the DSC is accomplished based on the protocol combining pinning control and in-group and intergroup information exchange of multi-agent system. Accordingly, the DSC of the MMG is converted to the distributed multiple DG-clusters control, and the control process is tuned to tracking group synchronisation to pinning-based anticipative consensus in DG-clusters. In this way, the implementation of many MMG functions, such as global coordination among MGs, local autonomy in an MG, reliability, scalability, and self-healing are all simplified. Meanwhile, the dimensions of control and the number of controllers are dramatically reduced by pinning control. In addition, the requirements for a central controller and complex communication topologies are obviated. Simulation results are presented and discussed to illustrate the effectiveness, adaptability and advantages of the proposed control.