Accurate calculation of short-circuit currents in power systems is fundamental to the effective implementation of relay protection setting calculations. The integration of traction transformers introduces three-phase asymmetry into the power grid. To achieve a unified and efficient approach for short-circuit calculation in power systems containing various types of traction transformers

this paper proposes a general short-circuit fault model for power grids with traction transformers. By superimposing fault modified the nodal admittance matrix

the method can directly calculate the short-circuit voltages and currents throughout the entire network. First

the basic concept of power system fault analysis using a modified nodal admittance matrix is introduced. Then

the fault-modified nodal admittance matrices for low-voltage side faults of single-phase

V/V

V/X

Scott

and impedance-matched balanced traction transformers are derived in detail. Finally

the correctness of the proposed method is demonstrated by simulations based on the IEEE9-bus system and comparison with the existing calculation methods. The method has been applied in practical power grid fault analysis and relay protection setting calculation software

demonstrating good practicality and engineering value.