Alternative droop control method using a modified lag compensator for paralleled converters in DC microgrids

Abstract

Droop control is used to obtain load sharing between paralleled converters within a standalone/islanded DC microgrid. There are two main types of droop control methods used in DC microgrids; the impedance (V-I) droop and the admittance (I-V) droop. This paper presents an alternative droop control system built on the I-V droop method. The proposed alternative droop control system uses a modified Lag compensator to obtain voltage control, as well as load sharing between the paralleled converters within the DC microgrid. The control system consists of two nested controllers, an inner Proportional-Integral (PI) controller to control the current, and an outer modified Lag compensator to control the voltage and the droop. The proposed control system was modelled in Simulink, and the operation was tested by simulating two paralleled buck converters operated in the continuous current mode while sharing a common resistive load.