Study on the Computational Model for Frequency‐Dependent Impedance of Rails Incorporating the Effects of Cross‐Sectional Geometry

In addressing the issue of electromagnetic interference in railway environments, research into the coupling pathways, amplitude distribution patterns, and attenuation characteristics of such interference is crucial for identifying practical solutions. Rails, a common channel for signaling and traction power supply systems, play a pivotal role in anti‐interference design. However, due to their ferromagnetic material properties and irregular H‐shaped cross‐section, accurately defining their frequency‐dependent impedance has been challenging, leading to inaccuracies in the electrical modeling of railway stations. This paper proposes a segmented modeling approach for rails, analyzing and deriving the internal impedance calculation formulas based on the distinct shapes of each rail segment. Taking the working mode of track circuits as an example, the influence of external circuit loop impedance is considered, culminating in the development of a computational model for the frequency‐dependent impedance of rails. Using the 60 kg/m rail as an example, the model’s impedance calculation accuracy at specific frequency points deviates by less than 6% from standard errors. Additionally, leveraging the ANSYS platform, the finite element simulation method was employed to simulate the frequency‐dependent internal impedance of rails below 100 kHz. The results showed a high degree of agreement with the internal impedance parameters derived from the model, thereby validating the model’s accuracy within the frequency range below 100 kHz under long rail conditions. This model enhances the precision of station modeling, particularly in improving the accuracy of interference amplitude distribution and attenuation characteristic calculations.