Advanced Circulating Current Suppression and Voltage Regulation Schemes for Different Architectures of DC Microgrid

In this paper, an innovative control strategy to address circulating currents for different structure of DC microgrids is proposed. The strategy suggests a circulating current suppression (CCS) controller that estimates effective resistances to optimize current sharing among multiple sources. To counteract minor voltage drops caused by this suppression, a voltage-spread compensation (VSC) controller is implemented which dynamically adjusts the voltages based on the voltage-spread of the source converters. The results confirm that this control strategy not only effectively suppresses circulating currents but also significantly enhances voltage regulation, thereby improving the stability and performance of DC microgrid systems. The effectiveness of these controllers is validated through experiments on a 5-bus, 70V hardware prototype, demonstrating that the proposed controllers can achieve over 99.5% accuracy in reducing circulating currents and maintain voltage deviations within a 5% tolerance. The controllers are also tested across various scenarios, including energy storage system (ESS) charging and discharging, different system topologies, and varying droop resistances.