Impedance Model Based Dynamic Analysis Applied to VSG-Controlled Converters in AC Microgrids

Abstract

The virtual synchronous generator (VSG) control technique has proven to be an attractive solution to power flow control of distributed generation (DG) systems integrated in AC microgrid by using power converters. Thus, this paper presents the influence of Thevenin impedance seen by each DG unit on the dynamic performance of grid-connected converters controlled by using VSG concept. The dynamic analysis is based on a small-signal model suitable for describing the power flow transient characteristics of DG units operating in medium and high voltage networks. Based on this model, the Thevenin impedance parameters influence on the VSG controllers dynamic performance are discussed. The VSG technique performance in different operating scenarios is assessed by means of simulation results. The obtained results reveal the effectiveness of the theoretical analysis performed.