Adaptive droop control of unbalanced voltage in the multi-node bipolar DC microgrid based on fuzzy control

Multi-node bipolar DC microgrid can provide more voltage level interfaces and has higher security and reliability than the unipolar DC microgrid. However, in the multi-node bipolar DC microgrid, the operation of load and line resistance will lead to the deviation of DC bus voltage and increase the circuit power consumption which will affect the stable operation of the whole microgrid. In order to control the unbalanced voltage, an adaptive droop controller based on the fuzzy algorithm is innovatively applied in the design of a multi-node bipolar DC microgrid. This research mainly analyzes the influence of unbalanced load and line resistance on droop control in the multi-node bipolar DC microgrid. According to the analysis, an adaptive droop controller based on the fuzzy algorithm with the voltage deviation, voltage unbalance coefficient, and state of charge (SOC) as inputs is designed to obtain the correction of the droop coefficient. The model of a multi-node bipolar DC microgrid is established in MATLAB/Simulink platform and the effectiveness of the proposed adaptive droop control based on the fuzzy algorithm is verified through the simulation results.