Impedance Transfer Functions Fitting Methods of Grid-connected Inverters: Comparison and Application

This paper presents a detailed comparison and practical application among Vector Fitting, Complex Curve Fitting, and Matrix Pencil for the impedance transfer functions fitting of grid-connected inverters. Firstly, the theoretical principles of each method are briefly introduced. Secondly, all methods’ computational performances and fitting accuracy are compared through a grid-connected inverter model built in hardware in the loop real-time simulation platform. Finally, the results of fitting are applied in the analysis of harmonic stability, the effectiveness and practicability of fitting methods are further verified and expanded.