Small-Signal Stability Analysis of Grid-Connected Converter under Different Grid Strength Cases

Nowadays, the need for a more sustainable power system is leading to the utilization of power-electronic converter technology (eg. in wind and PV applications); however, stability issues in converter-based power systems have been under discussion for a while. In this paper, a small-signal model is developed to analyze the control dynamics of grid-connected power converters and investigate the impact of control gains on the system stability. The dynamics are expressed using a nonlinear state-space modeling system and the sensitivity level of this model is studied in details. Linearization is implemented around the equilibrium points of the system and stability is assessed through its eigenvalue analysis. Time-domain simulations are performed to verify the accuracy of the model and corresponding FFT analysis are obtained when instability occurs in order to validate the small-signal analysis model.