Droop control of a bipolar dc microgrid for load sharing and voltage balancing

摘要

A bipolar dc microgrid features three voltage levels and is capable of transmitting power more efficiently than a unipolar system. This paper proposes a droop control to achieve load sharing and voltage balancing in such a microgrid system. Droop control is adopted to ensure that autonomous sharing of load power can be realized without communication. Moreover, the positive and negative pole voltages in the bipolar dc microgrid can be well regulated regardless of load changes and input voltage mismatch. Two battery energy storage systems are incorporated for balancing load and generation, and the lifetime of batteries can be improved through proper coordination control. Simulation results in the PLECS environment and experimental results obtained from an OPAL-RT system are presented to verify the effectiveness of load sharing and voltage balancing of droop control.