Sequence Impedance Modeling and Stability Analysis of Single-Phase Converters

Abstract

The utilization of a large number of power electronic converters in power systems results in many kinds of stability problems, such as low-frequency oscillations and harmonic instability and so on. The impedance-based stability analysis method can be employed to effectively study the stability of converter systems, so it is important to establish the precise impedance model for stability analysis. Firstly, based on the application of single-phase converters in high-speed railway electric multiple units, a sequence impedance model based on harmonic linearization is established. Secondly, an approach of impedance measurement method based on the frequency-scanning method and impedance calculation method considering of positive and negative frequency signals are presented. The input impedance is respectively measured by Simulink offline simulations and experiments of hardware in the loop base on the frequency-scanning method and is compared with theoretical modeling impedance. The results prove the accuracy of sequence impedance modeling based on harmonic linearization. Finally, the stability of the simplified vehicle-grid coupling system is verified by generalized Nyquist stability criterion.