An overview on consensus-based distributed secondary control schemes in DC microgrids

Secondary control (SC) is the middle layer of the well-known hierarchical control structure, which plays an essential role in maintaining the desired operation of microgrids (MGs). Generally, SC layer is divided into three categories of decentralized, distributed, and centralized control schemes. Among them, distributed control strategy is superior to the decentralized and centralized ones in terms of effectiveness, reliability, and scalability. Accordingly, this paper presents a comprehensive overview on distributed secondary control (DSC) schemes in DC MGs, specifically focusing on consensus-based cooperative DSC schemes. In this overview, the consensusbased DSC methods are classified into five groups of dynamic consensus, leader-follower consensus, finitetime consensus, PI consensus, and event-triggered consensus. These consensus-based DSC strategies are investigated, reviewed, and assessed in detail. Furthermore, different case studies are provided to compare the performance and merits of different consensus-based cooperative DSC structures using time-domain simulations in MATLAB/Simulink environment. Key findings are provided, and finally, challenges ahead of future research are highlighted.