A Consensus-based Droop Control with Adaptive Virtual Impedance of Grid-Forming Converters

Abstract

This article presents a consensus-based droop control to achieve accurate active and reactive power sharing among distributed grid-forming (GFM) converters. Regardless of the mismatched distribution lines, this method is realized through the adaptive modification of the line impedance based on the virtual impedance concept. Different from common methods that use reactive power mismatch to generate consensus signals, the proposed method takes account of both active and reactive power errors to correct the value of virtual resistance and reactance for the coordination of the power-sharing performance of distributed GFM converters. To demonstrate the usefulness of the proposed control method, a microgrid consisting of four GFM converters and two resistive-inductive loads is built in MATLAB/Simulink. Several case studies including the steady-state operation of four paralleled GFM converters, sudden load changes, the disconnection of one GFM converter, and the communication failure, are conducted to test the performance of the proposal consensus-based droop control. Results show that the proposed method can ensure the good maintenance of voltage and frequency stability through accurate proportional sharing of active/reactive power.