Large Disturbance Stability Analysis of System with Paralleled Grid Following-Voltage Source Converter and Grid Forming-Voltage Source Converter

The grid following-voltage source converter (GFLVSC) and grid forming-voltage source converter (GFM-VSC) are connected to the grid in parallel to maximize the tracking of the new energy output as well as to provide frequency and voltage support in the paralleled system. However, paralleled system also has the risk of instability under the working conditions with large disturbances. In this paper, based on the TS fuzzy model and the Lyapunov direct method, the stability region of paralleled system is estimated by solving the linear matrix inequalities, which is used to analyze the influence of system parameters on the stability under large disturbances. Firstly, the mean value model of paralleled system of GFL-VSC and GFM-VSC is established and converted into a TS fuzzy model. Then, the Lyapunov stability criterion of paralleled system is solved using linear matrix inequality to estimate the domain of attraction (DA) of paralleled system. Based on the DA, the effects of system parameters and control parameters on the stability of the system with large disturbances are analyzed. Finally, the correctness of the estimated DA and the validity of the conclusion of the analysis of the influence of system parameters on the large disturbance stability are verified by MATLAB/Simulink simulation.