Minimization of Circulating Currents in Parallel DC-DC Boost Converter Using Non-Linear Droop Control for Battery Energy Storage System

Abstract

Battery is considered the most dominant energy storage device for renewable energy-based DC microgrid systems (RE-DCMG) because of its ability to store energy for a longer duration. Here the power electronic converter plays a vital role, which acts as a bridge between the energy storage system and DC microgrid. One of the main reasons for the failure of battery systems due to the failure of the power electronic converters. To improve the redundancy and converter failure issues of battery energy storage systems (BESS), parallel operation of multiple converters are required. However, the parallel operation faces an issue of voltage imbalance between the converters which gives rise to an input circulating current. To address these issues, in this paper, we propose a nonlinear droop control based parallel DC-DC boost converter for battery energy storage system. The nonlinear droop control strategy ensures the equal battery current sharing between the parallel converters and good output voltage regulation. Moreover, SOC based controller avoids over-charging and over-discharging of the battery and the parallel converters ensure the redundancy in operation. The proposed system is designed and implemented in the MATLAB/Simulink and compared with the existing linear droop control.