Logarithmic droop-based decentralized control of parallel converters for accurate current sharing in islanded DC microgrid applications

Abstract

Remarkable progress in distributed power generation invigorated research into DC microgrids using a controllable DC–DC converter contingent to the functionalities therein. The study explores the circulating current issue in a parallel-connected DC–DC converter and its associated current-sharing capability. Despite, the conventional droop being a promising solution with less control complexity, the current sharing is achieved at an expense of voltage drop. The prime objective of this research work is to design a control strategy that guarantees a minimized circulating current with proper current sharing for a parallel-operated DC–DC converter. This paper puts forth a dual reference-based control to alleviate the droop and load effects of the system. The primary reference is generated by considering the effect of a marginal change in the input power of the converters. The virtual resistance-based droop technique utilizes the prime reference for secondary droop reference generation. A current sharing algorithm is designed to assimilate adaptability to the scheme running under a variable line and load parameters. The comprehensive approach to the proposed control strategy has the advantages of improved current sharing and voltage regulation. A parallel DC–DC converter with the proposed control mechanism was investigated using MATLAB/Simulink and validated experimentally.