Reduced-order Modeling of Grid-forming Inverters Based on Frequency Domain Perturbation Operator

Compared to the grid-following (GFL) control, grid-forming (GFM) inverters have a more intricate control structure, increasing the computational burden in stability analysis. Drawing inspiration from singular perturbation ideas, a frequency domain perturbation operator is proposed for model order reduction in this paper. The shift from state variable perturbation to state matrix perturbation standardizes the expression of reduction models across different frequency bands. On this basis, adjusted cosine similarity and difference vector are introduced to determine the transition points of the reduced-order models. Ultimately, a reduced-order model for GFM inverters under various parameter conditions is constructed. The correctness of the reduction method has been verified through amplitude and phase response characteristics. In the low, mid, and high-frequency ranges, the model order can be reduced to 54.5%, 72.7%, and 18.2% of the original, respectively. The influence of parameters on the transition point is analyzed, revealing the primary influencing parameters for each time-scale model.

Recommended citation: Yanhui Xu and Yundan Cheng, "Reduced-order Modeling of Grid-forming Inverters Based on Frequency Domain Perturbation Operator," 2024 IEEE Power & Energy Society General Meeting (PESGM), Seattle, WA, USA, 2024, pp. 1-5.