Multi-Energy Storage Control Based on SOC for DC-Microgrid

In order to control and use the highly random distributed renewable energy and the load with high demand fluctuation better, the energy storage system must be equipped in the microgrid. In DC microgrids, due to differences between battery energy storage system units, the same charge and discharge rate is likely to cause overcharge or overdischarge of the energy storage battery. In order to extend the life of the energy storage battery, the improved droop control strategy should be used to balance the output of each energy storage unit according to the respective state of charge of the distributed energy storage. Regarding the issue above, this paper introduces a new droop control reference voltage and coordinates the energy storage unit output by adjusting the droop control reference voltage. According to the respective state of charge and output power of distributed energy storage, over-charging of energy storage units can be avoided with low SOC(State-of-Charge) energy storage unit over discharge or high SOC energy storage unit over charge. Finally, the effectiveness of the proposed strategy is verified by Matlab/Simulink simulation.