A Distributed Cooperative Secondary Control Scheme for Obtaining Power and Voltage References of Distributed Generations in Islanded DC Microgrids

Due to the widespread adoption of DC source-based distributed energy resources (DERs) and loads, alongside advancements in power electronics technology, DC microgrids (DC MGs) have recently gained significant attention. To effectively implement DC MGs, it is crucial to employ a suitable control strategy that maintains the bus voltage at the desired level and ensures appropriate power sharing among the integrated DERs. To address these objectives, a two-layer control scheme is proposed in this paper. In the primary layer, a customized droop control scheme is introduced, which applies lower voltage drop in comparison to the conventional droop strategies. Simultaneously, in the secondary layer, a modified voltage controller  which is supplemented by a term to enhance power sharing in a distributed manner is employed,. The proposed control strategies are characterized by their simplicity and low communication infrastructure requirements. To assess the efficacy of the proposed control architecture, several case studies, including plug and play integration, load variations, and communication challenges, including link disconnection and noise effects, are conducted. Additionally, the performance of the proposed strategies is benchmarked against an architecture featuring conventional primary droop control and cooperative distributed secondary control approaches. The simulation studies conducted in MATLAB/SIMULINK software demonstrate that the proposed control methods outperform the alternative approaches, confirming their effectiveness in maintaining voltage regulation and power sharing objectives.

Keywords:

DC microgrids , Distributed secondary control , Droop control , Power sharing , Voltage Regulation