Small-Signal Impedance Modeling and Nodal Admittance Matrix Stability Analysis for Virtual Synchronous Generator Controlled Grid-Forming Converters

The accurate calculation of the node conductance matrix of power systems has important theoretical value for small-signal stability analysis. With the maturity of grid-forming converters (GFCs) technology and the weakening trend of power grid caused by new energy scale access, the static stability of the system is facing a serious challenge, which makes the study of the static stability discrimination method of GFCs-dominated power system of urgent engineering significance. In this study, the impedance analytical model of GFCs is firstly established based on the small-signal modeling method, and the accuracy of the model is verified by wide frequency sweeping experiments based on the MATLAB/Simulink time-domain simulation platform. On this basis, it is proposed that a systematic stability discriminant criterion is constructed by comparing the consistency of the spectral distribution of the eigenvalues of the aggregated impedance matrix of the system with that of the eigenvalues of the nodal conductance matrix. Further, the correspondence between the system oscillation frequency and the calculation results of the critical stability eigenvalues is verified by establishing a time-domain simulation model in MATLAB/Simulink.