Consensus-based state of charge dynamic equilibrium strategy in isolated DC microgrid with bus voltage regulation

Abstract

Due to the tremendous benefits of integrating sustainable energy, the use of DC microgrid is gradually expanding. This paper presents a novel consensus-based State of Charge (SoC) dynamic equilibrium strategy to solve the issues of unbalanced SoC, imprecise load power distribution, and unreasonable bus voltage regulation for the Battery Energy Storage System (BESS) in DC microgrids with Distributed Sustainable Energy Generation (DSEG). In the communication layer, an adjacent communication network is built, which applies the Dynamic Average Consensus Algorithm (DACA) to estimate relevant average values. In addition, the conventional droop control is applied to distribute the load power preliminarily in the main control layer. With the proposed scheme, the dynamic SoC equilibrium and accurate current distribution are realized by the consensus iteration of the designed coupling factor, and the bus voltage recovery is achieved by compensating for the average output voltage of energy storage units (ESUs) in the secondary control layer. Furthermore, the exponential function is introduced to modify DACA, thus accelerating the convergence of DACA. Finally, the simulation and experimental results show that the proposed scheme can realize the control objectives of rapid SoC equilibrium, accurate load power distribution, and reasonable bus voltage regulation.