Analysis of Variable-Parameter Sequence Impedance of Grid-Forming Inverters Under Variable Power Conditions

With the establishment of China’s “dual carbon” goals, renewable energy sources such as wind power and photovoltaics, interfaced with the grid through power electronic converters, have developed rapidly. The large-scale integration of these energy sources introduces uncertainties and fluctuations into the power grid. Grid-forming inverters outperform grid-following inverters in weak grid conditions. This paper first develops a grid-forming impedance model that accounts for frequency coupling effects and analyzes impedance characteristic variations due to control parameter changes at different operating points. Finally, Matlab simulation experiments verify the accuracy of the analysis presented in this paper.