Optimal Decision on Current Sharing and Voltage Balancing in DC Microgrids With Feedforward Input

Abstract

This article is concerned with the issue how to achieve proportional current sharing while realizing bus voltage balancing in DC microgrids, or vice versa. In order to address this issue, proportional current sharing is realized first and then the optimal bus voltage is obtained by using the least square method; Second, assuming that the bus voltage balancing is realized, the optimal current sharing is solved by using Lagrange multiplier method. It can be seen that the results of the two cases are identical. Then a global performance index relating to the generation capacities is presented to make an optimal decision on voltage balancing and current sharing. In order to decrease the communication burden, the distributed control schemes are proposed to replace centralized control strategies. It can be proved that the equilibrium points of distributed schemes are completely identical to the optimal solutions without significantly increasing system complexity. Finally, the effectiveness of the proposed distributed schemes is shown via a simulation example.