Dynamic Phasor Modeling, Stability Analysis, and Controller Design of Single-Phase Grid-Forming Converters

Grid-forming converters become the enabler of modern power systems. As distributed renewable energy sources gain popularity, the demand for single-phase grid-forming converters has risen as well. However, modeling such converters faces new challenges, which further hinder stability analyses and controller design. This article comprehensively investigates the single-phase grid-forming converter from the perspectives of modeling, analysis, and control. Regarding modeling, the nonlinear orthogonal signal generation unit, which is crucial for power measurement, currently lacks an accurate model. To address the problem, this article proposes an accurate dynamic phasor model, which can effectively capture critical dynamics. Furthermore, we analyze the small-signal stable boundaries of critical parameters. The analysis results demonstrate that the proposed dynamic phasor model can reliably predict instability phenomena caused by the phase lag arising from power measurement, achieving an accuracy improvement of over 65% compared with the common model. For stability enhancement, we propose a delay compensation power controller, which compensates the negative effect of the power measurement unit, improving the stability margin by over 40% compared with the conventional method. Finally, experimental results validate the improved accuracy of the proposed dynamic phasor model and the effectiveness of the proposed controller.