Impedance Modeling Method for Improving the Grid Stability of Grid-Forming Inverters

In the context of new energy generation, the application proportion of power electronic converters in the power system is constantly increasing, and the inertia and damping of the system are reduced, which leads to stability issues. This article focuses on the control strategy and stability analysis of grid-forming inverters, exploring different modeling and stability analysis methods. On this basis, this article adopts a virtual synchronous generator control strategy to determine the system topology structure of the grid-forming inverter. Then, a sequence impedance model of grid structured inverters based on virtual synchronous generators was established under three different inner loop control schemes, and the model was simplified. Furthermore, based on the established impedance model, stability analysis was conducted on the three-phase inverter grid-connected system.