Study on Distribution Characteristics of Metro Stray Current and Evaluation of Cumulative Corrosion Effect

Abstract

Stray current directly affects the regular operation of electrical equipment and facilities in the subway DC traction power supply system. Therefore, it is worthwhile to study the stray current distribution characteristics during train operation and the quantitative corrosion of buried pipelines. This paper introduces the traction characteristics of power carriages and power wheelsets of subway vehicles into the DC traction process. A finite element model considering the dynamic distribution of stray current under the actual operation of subway vehicles is established. The interference characteristics of stray current and the contribution of power sources under the multiparticle model are analyzed. The rail insulation damage caused by long service time and the quantitative calculation of rail and buried pipeline corrosion is considered. The model results show that the stray current in the buried pipeline under the multiparticle model is more accurate and more suitable for the protection in the actual subway. The quantitative corrosion of the buried pipeline is stronger than the partial insulation damage environment when the rail is not insulated. The rail and buried pipeline corrosion at both ends of the insulation damage position is relatively severe. The stray current distribution model established in this paper gives full play to the solution advantages of the finite element method and provides a new idea for the quantitative calculation of buried pipeline corrosion.

Analysis and ranking of corrosion causes for water pipelines: a critical review

“…To reduce stray current, one or more of the following can be done: a) Lowering the rail-return resistance; b) Increasing the leakage path to ground resistance; c) Increasing the resistance between ground and underground metallic pipelines; d) Increasing the metallic pipelines resistance 66 . In brief, the stray current can be alleviated by controlling rail return mode, blocking current leakage, and protecting affected pipelines 67 .…”

“…This occurs when a stray current enters the pipeline where the electrical voltage shifts to a large negative side, generating electrochemical reactions such as oxygen reduction and hydrogen evolution causing cathodic or coating disbandment 64 . Apart from that, hydrogen embrittlement occurs and the pipe material become brittle due to the entrance and diffusion of hydrogen into it 67 . Corrosion can also cause graphitization in cast-iron pipes, in which the iron dissolves and only the graphite remains.…”

Study on the Interference of the HVDC Transmission Grounding Electrode to the Pipeline Cathodic Protection System

“…In a DC transmission system, the steady-state electrostatic field is independent of the magnetic field. Therefore, the electric field can be described by the formula true{ .25ex2ex normal∇ · D = q normal∇ × E = 0 where q is the distribution of free charges in space and E is the electric field strength.…”

“…Therefore, the electric field can be described by the formula. 23 where q is the distribution of free charges in space and E is the electric field strength. Considering the soil as a uniform isotropic medium, we have …”

Influence of Stray Current on Fastening System Components in Urban Railway Tracks

“…Because the type and properties of fastening systems are selected depending on the required elasticity of the track, planned traffic load, and type of rail [48], the electrical resistance of the fastening system is not defined in the specifications. According to [36,42], even perfect rail insulation lasts only a few years if the tracks are not properly maintained; therefore, rail-to-ground resistance depends on the electrical resistance of the concrete base layer and the soil, which can vary greatly depending on the location of the tracks. Consequently, the rail-to-ground resistance values provided in the guidelines vary across countries for the same type of track construction, as shown in [49,50].…”