Droop control of current-source converters in bipolar-type DC microgrid

To provide 2 types of DC voltage, a bipolar-type DC micro-grid is adopted in this paper. The I-U droop control is proposed to achieve parallel operation of three-level converters in DC micro-grid. To solve unbalance potential of converters, the neutral point potential control is added into the I-U droop control. To eliminate influence of line impedance and improve the accuracy of power distribution, a secondary regulation is applied. The design of the controller and adjustment ability of neutral point potential are analyzed theoretically, and the results of corresponding experiments on a hardware-in-loop platform are presented to verify its correctness and effectiveness.