A dynamic droop control for a DC microgrid to enhance voltage profile and proportional current sharing

Equal load sharing among converters based on their rating and maintaining constant DC bus voltage are the main challenges in DC microgrids. The droop control method is the most effective solution to this problem. However, due to the fixed droop resistance used in traditional droop control method, accurate current sharing and voltage regulation are two opposing control goals. Because of unequal line resistance, the voltage deviation increases when the current sharing error decreases; when the voltage deviation improves, the proportional current sharing becomes unbalanced. The droop resistance value should be variable based on the load condition instead of a constant value to improve droop control. This paper proposes a new droop control algorithm that will update the droop resistance value based on the load demand. A new variable droop resistance is calculated for each variable load of the DC microgrid to maintain constant DC bus voltage and equal load sharing among converters based on their rating. The effect of local load and line resistance on current sharing and voltage regulation is considered in the control design. There is a load flow calculation and fitness function evaluation for every droop resistance change. The fitness function primarily assesses voltage deviation and proportional current-sharing errors. The effectiveness of this novel variable droop control method is evaluated using MATLAB/Simulink simulation and real-time simulator experimental studies.

Automated summary

Equal load sharing and maintaining constant DC bus voltage are the main challenges in DC microgrids. The droop control method is effective but has conflicting goals of accurate current sharing and voltage regulation. This paper proposes a new droop control algorithm that updates the droop resistance value based on load demand to improve sharing and regulation. The effectiveness of this method is evaluated using simulation and experimental studies.