Droop Control Based Battery Management System for Automated DC Microgrid

Abstract

This paper presents a method to control the charging and discharging rate and supply of power from the batteries in a DC microgrid by employing adaptive droop control utilizing State of Charge (SoC) as a parameter for droop coefficient. In a DC Microgrid it is essential to maintain uninterrupted power supply to the load, this is readily achieved by utilizing Energy Storage Unit (ESU) consisting of multiple batteries. In such a system it is while essential to maintain a constant power at the load end and ensure that the batteries provide power to the load and not to themselves due to the flow of circulating current however, the State of Charge (SoC) of different batteries is not always the same so the droop control is employed to attain pro-rata power sharing in them. In this study a SoC balancing method with an inherent circulating current blocking system is proposed. The battery which has greater SoC will supply greater power as compared to the one with lower SoC and vice versa as a result proportional discharging and charging rates shall be obtained which ensures that the batteries will always supply constant power. This shall be attained by using adaptive droop control wherein droop coefficients are related to the SoC.