Coordinated control of DC voltage magnitudes and state of charges in a cluster of DC microgrids

This paper presents a modified approach for the control of DC voltages and State of Charges (SOC) of batteries in an interconnected cluster of DC microgrids. First, the model of a DC microgrid is reviewed, and then the proposed control method is presented. This method is composed of two compensation terms that are introduced in the secondary control level in the hierarchical control framework of the microgrids. These compensation terms are used to control the voltage throughout the cluster, and also to equalize the SOCs over the cluster. Even though this method is proposed as a centralized controller, it is shown that it is possible to implement it in a decentralized manner, using a consensus algorithm to estimate the average state of charge locally. Moreover, a modification is proposed that gets the reference SOCs from the tertiary control level, and tries to control storage units based on these references. Simulations ae carried out and the results are provided. These results show the effectiveness of the proposed methods and modifications.