Abstract: Static var generators (SVGs) are widely used in photovoltaic (PV) stations because of their fast response speed and wide regulation range, which can meet such needs of the system as dynamic reactive power compensation. However, the existing research lacks the analysis of the harmonic interaction between SVGs and PV stations and power grids, and it often ignores the impact of SVGs on the harmonic resonance of PV stations. To solve this problem, this paper builds a new SVG model in the form of harmonic coupling impedance on the basis of multi-frequency harmonic response. The model can fully reveal the frequency coupling effect in the system and can be used to quantitatively analyze the influence of SVGs on the harmonic resonance of PV stations. Finally, the time-domain simulations of an actual PV station verify the correctness of the proposed harmonic impedance model and the importance of frequency coupling in harmonic resonance analysis.