A distributed control strategy based on droop control and low-bandwidth communication in DC microgrids with increased accuracy of load sharing

Abstract

A microgrid is obtained from the integration of several distributed energy resources such as fuel cells and storages. Droop control is a method for load sharing between sources or storages in a microgrid. In the conventional droop control method, one can only achieve one of the low voltage drops and accurate load sharing requirements by considering the line resistances. This paper proposes a new non-centralized control approach based on low-bandwidth communication (LBC) and the droop control method for the DC microgrid (DC-MG). The droop gain is calculated with respect to the output currents of the distributed generation (DG) units. Factors like different line resistances, different DG capacities, and the presence of local loads do not affect the controller performance. All calculations and control operations are performed locally and the LBC is used solely for transferring current information—this ensures high reliability. Simulations and experimental results show that the use of the proposed control method decreases voltage deviations and the effects of constant power loads (CPLs), while it increases system efficiency and the accuracy of load sharing.