Distributed-based Reactive Power Sharing in Islanded Microgrid

This paper proposed an adaptive impedance control method in multi-bus distributed islanded tnicrigrid to share reactive power accurately and suppress circulating current. The multi-bus distributed microgrid is more complicated than one-bus because of its different bus voltages and variable structure. To deal with the power sharing problem in multi-bus distributed islanded tnicrigrid, two methods have been applied: a distributed based adaptive virtual impedance control method has been proposed, in this method only local and neighbors' reactive power information are utilized to calculate reactive power mismatch, with this reactive power mismatch, virtual impedance correction is generated through a proportional integral (PI) controller, and the virtual impedance is updated in real time. Moreover, a droop controller has been improved to make the system more stable in multi-bus situation. Compared to traditional control method, the proposed method do not have to know global information and it is to adjust the output impedance of each DG to regulate output reactive power indirectly which is more stable and more flexible. Finally, simulation has been verified the effectiveness of the proposed control method.