this paper investigates the impact of the contact rail on the distribution of traction current harmonics in running rails due to the specific arrangement of the contact rail in the Metro. The objective of this research is to establish a theoretical foundation and provide a quantitative evaluation of how the geometric configuration of the contact rail induces systematic asymmetry in traction currents within the rail threads, asymmetry that can reach approximately 40 % under certain conditions. To this end, a frequency-dependent mathematical model has been developed to determine the rail-line parameters, accounting for the skin effect, mutual nductance between conductors, and the influence of choke transformers. An analytical expression for the complex coefficient characterizing magnetic influence asymmetry has been has been obtained. The proposed model has been validated by simulation in the MATLAB/Simulink environment, was validated. The relationship between the traction-current asymmetry coefficient and rail length has been computed and demonstrated across a broad frequency range. A concept of a critical rail-line length is introduced, beyond which the traction-current asymmetry coefficient does not exceed the normative value of 6%. This result can inform and improve the design of rail traction circuits.
Andrey Gennadyevich Kabetskiy (Fri,) studied this question.