For the transient stability issue of grid-forming voltage source converters (GFM-VSC)

most existing studies have assumed constant DC-side voltage

neglecting the influence of DC-side dynamics on the transient stability of GFM-VSCs

leading to overly optimistic analysis results. Therefore

this paper investigates a GFM-VSC grid-connected system considering DC-side dynamics

revealing a novel transient instability mechanism dominated by DC voltage dynamics and proposing corresponding stabilization methods. Firstly

a large-disturbance analysis model of the GFM-VSC grid-connected system

incorporating energy storage batteries and DC capacitor dynamics

is developed. Then

using equal-area criterion and phase-plane analysis

the transient stability mechanisms of the GFM-VSC under both unconstrained and constrained DC-side energy conditions are revealed. Subsequently

the impact of key factors such as energy storage battery capacity

DC bus capacitance

and current limiting components on the system’s transient stability is analyzed

with corresponding stabilization methods proposed. Finally

electromagnetic transient simulations are conducted to verify the correctness and effectiveness of the proposed mechanism analysis and stabilization methods.