Decentralized Cluster-Based Distributed Secondary Control of Large-Scale DC Microgrid Cluster System

With the high integration of distributed renewable energies, microgrid (MG) cluster system, consisting of complex physical structures and complicated networked control structure, has emerged as a growing trend. Currently, several secondary control strategies including centralized, decentralized and distributed control have been proposed to solve the secondary voltage restoration and power sharing problem in single DC MG systems. However, few efforts have been made on the secondary control of MG cluster system. In this paper, a first attempt on designing a decentralized cluster-based distributed secondary control strategy is made towards the goal of accurate voltage restoration and power sharing in the DC MG cluster system. Specifically, for the DGs within the same cluster, a distributed finite-time control approach is proposed, while no information exchange is involved among different clusters. As a consequence, all the distributed controllers of different clusters are totally decentralized. If each cluster has only one DG, our proposed control strategy reduces to the existing decentralized ones, while the case of one cluster boils down to distributed control. Rigorous theoretical analysis is provided for such control strategy. Compared to existing methods, our proposed strategy has better transient and steady-state performance than purely decentralized and better robustness than distributed ones. The proposed method is validated in an experimental test system built in OPAL-RT.