计及宽频带多耦合特性的并网逆变器统一阻抗建模与宽频带稳定性分析

During the interaction between inverters and the power grid or other devices, the wide-band dynamic characteristics and multi-frequency coupling properties of inverters may induce wide-band oscillations within the system, or even simultaneous oscillations across multiple frequency ranges. To investigate this complex oscillation problem, which has received little existing attention, the method of multi-harmonic linearization is adopted to investigate the impedance modeling of inverters considering multi-frequency couplings. This approach aims to establish a theoretical impedance model that comprehensively and accurately reflects the wide-band impedance characteristics of inverters. Based on the generalized Nyquist stability criterion, the wide-band stability analysis is carried out for single-inverter and two-inverter grid-connected systems, and the accuracy of the theoretical analysis results is verified through time-domain simulations. On this basis, the influences of system parameters on wide-band oscillations are analyzed. The research findings indicate that system parameters exert different influences on oscillations within different frequency ranges. Finally, a comparison of the proposed impedance model with other commonly used impedance models is carried out and validated by a hardware experimental platform that is closer to reality, illustrating the accuracy of the research work in this paper.