Distributed Secondary Control for Voltage Regulation and Optimal Power Sharing in DC Microgrids

In this article, a novel distributed secondary control scheme is proposed to solve the voltage regulation and power sharing problems of an islanded direct current (DC) microgrid. It not only eliminates the voltage deviation caused by droop control but also minimizes the total generation cost of the DC microgrid. The proposed secondary control of distributed generators (DGs) does not require global information, but only current information of neighbors and the DC bus voltage. Different from the existing secondary frequency control, the corresponding closed-loop system of the DC microgrid under the proposed scheme is a nonlinear networked system. With the help of the properties of cascade systems and the input-to-state stability theory, it is found that the DC microgrid under the proposed scheme can achieve voltage regulation and minimization of the total generation cost if the corresponding communication graph of DGs is connected. A simulation model is established to verify the proposed scheme. Finally, a DC microgrid platform with two DGs in parallel is used for the experimental verification.