An Improved Cooperative Control Method of DC Microgrids Based on Finite Gain Controller

DC microgrids have gained a lot of consideration over its AC counterpart due to its increased efficiency, reduced volume, greater flexibility and capital cost. The control objectives in the literature for secondary/primary control of DC microgrid are voltage regulation and proportional load sharing, which requires the proper voltage set-point for the particular converter. In conventional approach, primary controller voltage point is adjusted conferring to average value of voltage and current of the whole system. In this paper considering the objective of secondary/primary control of a DC microgrid, an improved technique is proposed. A finite gain voltage controller is introduced to achieve droop like performance with one P controller in current loop, and finite gain controller in the voltage loop of buck converter. To reduce the communication delay effect, a different method is implemented to measure the average voltage and current difference. Key advantages of the proposed technique are simple design, flexible communication structure, better stability and higher scalability. Based on this new structure of individual converter, a four-node DC microgrid setup with ring communication structure is examined in MATLAB/Simulink environment and simulation results verify the efficiency of the improved proposed technique.