Suppression of Circulating Current in Islanded dc Microgrid Using a Decentralized Adaptive Line Resistance Approach with Secondary Leaky Integration Control

This paper presents a fully decentralized Islanded DC Microgrid for circulating current suppression, current sharing and voltage restoration using a communication-free leaky integral control with localized adaptive droop line resistance estimation. Circulating current is produced when parallel-connected converters in a DC Microgrid exhibit mismatched output voltages which makes converters output current rating higher than the rated values. To suppress this current and implement a fully decentralized islanded Microgrid, rather than an arbitrary allocation of line resistance value in the droop and leaky control, an adaptive line resistance approach aimed at realizing a completely decentralized Islanded Microgrid is implemented. The adaptive droop line resistance calculated from converters’ local parameters failed to restore DC bus voltage and the circulating current could not be suppressed in islanded solution, contrary to grid-tied system in literature. To rectify this in an Islanded Microgrid, a secondary leaky integral controller with adaptive line resistance term is used to suppress this circulating current with a minimal deviation in bus voltage regulation of 380Vdc. Both current sharing, suppression of circulating current and voltage restoration is realized.