Distributed Secondary Control for DC Microgrid with Virtual Voltage Compensation

DC microgrids are increasingly being applied in current power systems while droop control is often used for its control. Adding droop control to the voltage and current dual closed-loop control can achieve primary current sharing, but it will cause voltage deviation of the DC bus. To achieve current sharing while restoring bus voltage, secondary control is applied in control systems. This paper proposes a new secondary control scheme that utilizes the concept of 'virtual voltage drop', realizing accurate current sharing and voltage restore. Through the information exchange between neighboring distribute generators (DG) the local average value of virtual voltage drop is equal to the overall average value. In addition, the proposed secondary control scheme has no load limitations and can handle resistive and constant power loads. Ultimately, the simulation verification is conducted in MATLAB Simulink.