A New Power Flow Control Method for Energy Storage Systems in Microgrids (MGs)

This paper introduces a new power flow control method for the energy storage systems used in DC microgrids (MGs). The proposed control method is an adaptive droop control-based method that keeps the DC-bus voltage in a predefined and desired range. In the islanded mode of operation, tightly regulating the bus voltage is very challenging. The proposed control technique utilizes a nonlinear droop profile with four adaptive parameters, which are able to tightly regulate the bus voltage during various changes in loads/sources within a DC MG. In addition, determination of the adaptive parameters are performed by using a nonlinear optimization method. The sequential quadratic programming (SQP) optimization considers both the state of charge (SOC) of the battery and the DC MG voltage to make the control system more reliable and efficient. Simulation and experimental results verify the feasibility of the proposed approach and demonstrate its superior performance in comparison with the conventional controllers.