Grid-forming control technology

due to its active support capabilities

is increasingly applied in modern power systems. However

grid-forming inverters are prone to overcurrent phenomena during grid short-circuit faults. To address this issue

virtual admittance is commonly employed to limit short-circuit currents

yet the equivalent modeling of virtual admittance in fault current analytical calculations remains a critical challenge. This paper proposes an equivalent impedance-based short-circuit current calculation method for virtual synchronous generator (VSG) grid-connected systems utilizing virtual admittance current limiting

under three-phase symmetrical short-circuit fault scenarios. First

based on traditional short-circuit current calculation principles

the expression for short-circuit current calculation using equivalent impedance is derived. Second

the equivalent impedance is solved under the current inner-loop stabilization time scale

and a fault equivalent model for VSG inverter power sources is established

and an analytical expression for short-circuit current that takes account of variations in virtual internal potential is deduced. Subsequently

the influence of different control parameters and fault severity levels on the VSG short-circuit current is analyzed by using the derived expression. Finally

the correctness of the proposed equivalent impedance-based VSG short-circuit current calculation method and the related influencing factors analysis is validated through simulations on the MATLAB/Simulink platform.