Modeling and Transient Stability Analysis of Mixed-GFM-GFL-Based Power System

The transient stability mechanism of grid-following inverter (GFL-inverter) and grid-forming inverter (GFM-inverter) in the power system has been extensively studied respectively, whereas the integration of GFM-inverters and GFL-inverters into the grid unavoidably change the transient stability of the power system. This paper aims to analyze the transient stability for the mixed-GFM-GFL power system (MGGPS). The equilibrium point of the MGGPS system is analyzed. The large-signal model of the system is established. Based on this model, an analysis of the transient stability is carried out. It is revealed that the change of GFM-inverter terminal voltage will move the position of GFL-inverter equilibrium points, and the increase of GFL-inverter terminal current will enhance the transient stability of GFM-inverter. With the simulation of phase portraits, the aforementioned transient stability mechanism is proved.