Unbalanced voltage control of bipolar DC microgrid based on distributed cooperative control

The change of positive and negative DC load of bipolar DC microgrid will cause the voltage of dc-bus to deviate from the rated value, causing the positive and negative voltage to be unbalanced, and will increase the network loss. In order to coordinate the participation of different distributed power sources in the unbalanced voltage control of DC microgrid, this paper adopts the distributed cooperative control combined with primary control and secondary control. The droop control is taken as the primary control link of the bipolar DC microgrid, and an unbalanced voltage observer and an unbalance factor controller are established based on the consensus algorithm as a secondary control link to integrate the average dc-bus voltage and the voltage unbalance factor control. In this way, the voltage unbalances between poles and the average dc-bus voltage will reach consensus and maintain at the rated value. The simulation platform of bipolar DC microgrid is built in MATLAB/Simulink, and the effectiveness of the control strategy is verified.