Fuzzy PID Controller for Adaptive Current Sharing of Energy Storage System in DC Microgrid

Abstract

In DC microgrid, conventional droop control is widely used to perform current sharing of distributed energy storage system. Although, this method has distributed and reliable characteristic, it cannot achieve accurate current sharing due to mismatched line resistances. Moreover, thermal effect causes these line resistances to change over long-term operation, which makes unequal current sharing more seriously. To overcome this problem, adaptive virtual resistance is applied in order to achieve accurate current sharing among energy storage system in DC microgrid. The virtual resistance is regulated by means of a Fuzzy PID controller in this paper. Although Fuzzy controller is widely used in literature, it has not been realized for achieving accurate current sharing in DC MG. Thanks to Fuzzy PID controller, the dynamic response becomes faster and the stability of the microgrid system are improved in comparison with the conventional PID controller. The proposed method is validated through the simulation using Matlab and Simulink.