On-line Monitoring and Analysis of Urban Rail Transit Stray Current

Abstract

Objective To ensure the safe operation of underground gas pipeline network near URT (urban rail transit) and to mitigate the electrochemical corrosion on the gas pipeline network caused by URT stray current, it is necessary to conduct online monitoring and analysis of URT stray current. Method Real-time continuous pipe-ground potential data from four monitoring points set up on underground gas steel pipelines near a section of Tianjin URT are obtained. A combined time-frequency domain analysis is conducted on this data. A continuous wavelet transform model is established, and a wavelet power spectrum analysis is performed. Wavelet coherence analysis is utilized to study the coherence degree and phase relationship between pipe-ground potential signals. Result & Conclusion The pipe-ground potential signals under the interference of URT stray current are a typical non-stationary signal, with certain pattern of periodic fluctuations. The intensity of these periodic fluctuations increases non-linearly as the distance to the interference source decreases. The periodically changing pipe-ground potential presents an overall waveform of a mountain-shape parabolic curve, peaking most noticeably within the 64-128 minute range. During URT operation, the coherence intensity between signals shows significant variability, with strong coherence only appearing at some intervals. Additionally, the leading or lagging angles of the inter-signal phase correspond to the operation intervals of URT trains.

Keywords

• urban rail transit
• stray current
• on-line monitoring