Investigation of small signal dynamics of inverter-based Distributed Generation in grid-connected and autonomous modes of operation

A Distributed Generation (DG) unit can be operated either in grid-connected mode or in autonomous mode and has to possess the essential dynamic stability in both cases. This paper presents a systematic approach to small-signal modeling of an inverter based DG unit in grid-connected, autonomous and transient from grid-connected to autonomous modes of operation. A first order eigenvalue sensitivity analysis is done to investigate the effect of changing different parameters on eigenvalues and system dynamics both in the low and high frequency ranges. Simulation results show an acceptable agreement with the loci of eigenvalues.