Distributed Hierarchical Control for Voltage Stability and Proportional Current Sharing in Island-Mode DC Microgrids

This paper presents a novel distributed hierarchical control method for ensuring voltage stability at the common connection point and achieving proportional current sharing among power converter elements in island mode DC microgrids. The proposed control method operates in two levels, namely primary and secondary control. The primary control employs droop control to achieve proportional current sharing, but it introduces bus voltage deviation. To address this, the secondary control incorporates a voltage regulation term to correct the voltage deviation, while also preventing current distortions through a current regulation term. Furthermore, a dynamic consensus algorithm is employed to estimate the energy parameters of the entire microgrid using data from neighboring controllers, reducing the communication burden and distance compared to central hierarchical control. The LORA communication modules are employed to facilitate communication, enabling the establishment of widely spread microgrids. Experimental validation of the designed distributed hierarchical control is conducted on a laboratory microgrid, and the obtained results are presented.