Consensus based distributed secondary control for current sharing and voltage restoration considering local loads and constant power loads in dc microgrids

Abstract

ABSTRACT Ensuring accurate current sharing and regulating output voltage is challenging in DC microgrids. Conventional droop control has limitations in achieving voltage regulation and accurate current sharing. Unequal transmission line resistances, local loads, and constant power load (CPL) add to the complexity. To tackle this issue, this paper presents a novel consensus based distributed secondary control that determines the resistance of transmission lines by injecting an external pulse to the reference voltage of each converter, and then measuring the resulting changes in output voltage and current. The proposed secondary control signal, denoted as ψi , enables simultaneous proportional current sharing and voltage restoration in the DC microgrid. To guarantee the stability of the proposed method, a comprehensive stability analysis of the system is performed. In contrast to similar methods, the proposed method enables achieving precise proportional current sharing and voltage restoration, even when faced with varying resistive loads and CPLs. Furthermore, the proposed method exhibits remarkable features including, high convergence speed, the capability to determine transmission line resistances instead of assuming them to be known, and robustness in plug-and-play scenarios and communication system failures. The proposed method is validated through simulations in MATLAB and experimental tests, affirming its effectiveness.