Distribution Power Loss Mitigation of Parallel-Connected Distributed Energy Resources in Low-Voltage DC Microgrids Using A Lagrange Multiplier-Based Adaptive Droop Control

This article presents a Lagrange multiplier-based adaptive droop control to mitigate distribution power loss of parallel-connected distributed energy resource (DER) systems in dc microgrids. The distribution power loss comprising line loss and converter loss can be modeled as a quadratic function of the output currents of the DER systems, which can be optimized by the tertiary-layer Lagrange multiplier method to obtain the optimal output current references for the secondary-layer adaptive droop control. The output currents are compensated by the adaptive droop control to provide output voltage references for the primary-layer local dual-loop control, which is a conventional local control scheme for the regulations of grid-connected dc-dc converters. Both simulation and experimental results validate that the proposed control strategy can reduce the distribution power loss of parallel-connected DER systems in 48 V dc microgrids as compared to the conventional control strategy by only optimizing the line loss in different cases.