An Improved Droop Control Method for Energy Storage Module of DC Microgrid

Abstract

This paper proposes an improved droop control method with state of charge (SOC) balance function for energy storage module of DC microgrid. The average SOC of all energy storage modules is obtained by low bandwidth network. The SOC balance controller calculates the difference between each module’s SOC and average SOC and then adjust the droop coefficients according to the difference. As the coefficient changes, the output power of module is allocated according to its SOC and eventually achieve balance. Besides, secondary voltage controller is employed to compensate DC bus voltage drop. Also, the stability of the proposed method is studied by small-signal analysis. The effectiveness of the proposed method is finally verified by MATLAB/Simulink simulation.