Third-Order Energy Function Modelling Approach for Grid-Forming Converters

The grid-forming (GFM) controlled converters are used to enhance the voltage support capacity of the power system. However, in the GFM control, the power-coupling between the active and reactive loops can greatly affect the synchronization process between the converter and the AC grid. In this paper, the influence of power-coupling on the transient stability of converters is studied. Firstly, the third-order nonlinear model of the GFM converter is established. Compared with the spring-plane pendulum physical model, the energy function model of the GFM converter can be obtained. Then, based on the proposed energy function, the influence of power coupling on the transient stability of the converter is analyzed. Finally, the correctness of the above theoretical analysis is verified in the MATLAB/Simulink platform.