This paper takes a single virtual synchronous generator(VSG) as the research object and proposes an analytical calculation method for short-circuit current based on the VSG control architecture. Firstly

the differences in fault current calculation between grid-forming VSG-controlled and traditional grid-following systems are clarified

as well as the impact of control loops such as the virtual synchronous loop. Subsequently

the solution steps for the analytical expression of VSG short-circuit current are established through reasonable assumptions. For multi-machine stations or clusters

the feasibility of equivalent aggregation using a single-machine model is discussed. It is pointed out that analytical calculation will face the problem of dimensionality explosion when the scale expands

where numerical simulation is more advantageous. Therefore

the proposed analytical method is mainly suitable for single VSG or small-scale systems. The method has a simple calculation logic and provides an operable mathematical framework for analyzing VSG fault current characteristics. The simulation results have verified the correctness and effectiveness of the proposed analytical calculation method.