A Power Sharing Strategy for Islanded DC Microgrid with Unmatched Line Impedance and Local Load

The novel load power sharing control strategy is proposed for parallel-connected distributed generation units of islanded DC microgrid considering both unmatched line impedance and local load. Because the output voltage of DGs may be different, so the accurate load power sharing cannot be assured only by using conventional droop control method. Therefore, the improved droop control based on virtual voltage is designed to replace the actual output voltage, which can reduce the voltage deviation and achieve the accurate load power sharing among parallel-connected DGs in proportion to their rated power. Meanwhile, the droop coefficient setting principle is also designed to avoid large DC bus voltage drop. Furthermore, the stability analysis can be added to guarantee the stability operation of DC microgrid theoretically. The proposed control strategy may be realized locally, which need not to change the control scheme even when DGs and loads are increased or decreased. Finally, the effectiveness of the designed control scheme can be verified through Matlab/Simulink software, at the same time, the experimental results are carried out on real-time digital simulation platform.