Equal Load Sharing in DC Microgrid Using Line Resistance Estimation

The objective of this work is to achieve equal load sharing among parallel-connected converters by estimating the line resistance. Difference in line resistance leads to unequal power sharing in parallel-connected converters. Unequal load sharing is eliminated by droop control method. However, voltage regulation at the DC bus puts a limit on value of droop constant. To eliminate unequal power sharing estimation of the value of resistance of interconnecting cable is done by local voltage and current values of a converter. The estimated value is used to adjust the voltage reference so as to compensate the voltage drop on the connecting cable. This improves voltage at the DC bus and also leads to equal load sharing among converters. The proposed method has been validated through simulation of three parallel-connected boost converters.