Effect of Soil Salt Content on Stray Current Distribution in Urban Rail Transit

Abstract

In order to study the effect of soil salt content on the stray current distribution in the urban rail transit, a threelayer stray current resistance network distribution model of " rail -drainage net-ground" is established based on the method of resistance network. The mathematical model is established by using the equivalent circuit of micro-element, and the analytical expressions of voltage and current of each metal structure are derived. Then, the simulation model is established with MATLAB/Simulink software, and the simulation results are consistent with the analytical results. A small-scale experimental platform corresponding to the model is built, and the changes of leakage current and the stray current in soil samples with different NaCl content are measured. The experimental results show that the leakage current and stray current in soil samples increases with the increase of NaCl content. Finally, the experimental results are verified by the established simulation model and the simulation results are basically consistent with the experimental results, which proves the accuracy of the experimental results. The research results can provide a theoretical basis for the protection design of subway stray current.

Discrete modeling and calculation of traction return-current network for 400 km/h high-speed railway

“…To prevent stray DC from corroding underground pipes, drainage nets are commonly used to collect stray currents and return them to the traction substation. [24][25][26] Fortunately, the AC electrified railway adopts a different system configuration with the dedicated grounding wire which plays the role of collecting stray currents in the soil to provide a return path for the traction current through the physical channel. Besides, as a metal conductor laid on the sleepers and ballast bed, the current in steel rails will also leak into the earth.…”

Research on the Influence of Urban Subway on Neutral Current of High-Voltage Substations Along the Line Under Complex Environment

“…There will be current leaks from the rails into the ground during the running process of the subway train. This part of the current may return to the traction substation through the ground or buried metal structures, which is called stray current [1,2]. The stray current causes the change of the nearby ground potential, causing the potential difference between adjacent substations, which in turn affects the neutral point current of the substation.…”