Stability Analysis of Grid-forming and Grid-following VSCs in Parallel Connected to Weak Grid

Generally, grid-following converters have current source characteristics, while grid-forming converters have voltage source characteristics. The parallel connection of the two to the AC power grid has more complex control characteristics, which can cause new stability issues. This article focuses on the stability issues of hybrid grid-forming and grid-following converters connected to weak current networks. The following work is carried out: Firstly, a stability analysis model for the hybrid converter system connected to weak current networks is established. Then, the influence of system operating points and control loops on the stability of the hybrid converter system is studied through modal analysis method. Finally, the experimental verification of the above analysis results was carried out through the integration of a grid type and a grid following hybrid converter system into a weak current network.