Unveiling Stability Insights of Model Predictive Current Control in Voltage Source Converter through Impedance Analysis

Model-predictive current control of Voltage Source Converters has demonstrated superior performance over conventional Proportional-Integral control in terms of total harmonic distortion and dynamic response. However, the small-signal stability properties of the Model Predictive Control (MPC) remain insufficiently explored in the literature. This paper investigates the stability characteristics of the MPC using Impedance-based Stability Analysis. An impedance model of the MPC controlled converter is developed and validated through simulation-based measurements. Furthermore, the effect of model mismatch, switching frequency, and sampling time on the impedance of the MPC-based converter is analysed. A simulation study is conducted, demonstrating that MPC achieves a higher stability margin compared to PI control under weak grid conditions.