Distributed Control Strategy Based on Line Impedance Identification for Reactive Power Sharing in Microgrid

In microgrids (MGs), general distributed control schemes cannot achieve both accurate power sharing and voltage recovery under the unknown and difference of line impedances. To solve this problem, a new two-level scheme based on line impedance identifications and distributed communication is proposed for AC microgrids with any line impedances. Firstly, a distributed estimator is designed to identify the bus voltage and line impedance parameters. Secondly, a unified droop control based on line impedance estimation is proposed to achieve reactive power sharing without considering line impedances mismatching. Finally, a distributed compensation protocol based on bus voltage identification is presented, and accurate voltage recovery and reactive power sharing for AC microgrids are obtained. Small signal stability analysis and simulation results verify the effectiveness of the proposed strategy.