| AC traction power supply system for urban rail transit has become a hot research topic due to its advantages such as strong power supply capacity,low construction costs,large carrying capacity,and environmental protection and energy conservation.However,due to its unbalanced single-phase power frequency AC power supply system,strong electric and magnetic fields will be generated during operation,causing serious AC interference to nearby buried pipelines,resulting in corrosion of the pipeline surface,which poses a threat to the operational safety of buried pipelines.Therefore,conducting research on the potential distribution of buried pipelines under AC interference from urban rail transit has important significance for pipeline corrosion protection and ensuring pipeline safety.This thesis comprehensively utilizes analytical model derivation,numerical model simulation,monitoring system design,and simulation experiment verification methods to conduct research on the potential distribution of buried pipelines under AC interference of urban rail transit.The main research contents are as follows:(1)This thesis introduces the principle of single-phase power frequency traction power supply system and segmented power supply technology for urban rail transit,as well as the voltage level and current distribution of AC traction power supply system.The main interference modes of AC traction power supply system on buried pipelines are discussed.The corrosion mechanism and harm of buried pipelines under AC interference of urban rail transit are summarized.(2)Based on the electromagnetic coupling theory,the equivalent circuit model of the pipeline to the earth circuit is established.According to the relative position of the locomotive and the pipeline,the research is divided into two working conditions: single and double sides.The analytical models of potential distribution of buried pipelines under two AC interference conditions are established respectively.The general law of potential distribution of buried pipelines under AC interference of urban rail transit is analyzed through Matlab simulation software.The analytical model is used to analyze the potential distribution of buried pipelines under different working conditions.(3)Based on CDEGS simulation software,a numerical simulation model of electromagnetic coupling between urban rail AC traction power supply system and buried pipeline is established.By changing the position of current injection points,simulation is conducted for both single and bilateral working conditions.The numerical simulation results are compared with theoretical calculation results to verify the correctness of the mathematical analysis model.The numerical simulation model is used to analyze the influence of different factors on the potential distribution of buried pipelines.Based on the numerical simulation model,reasonable suggestions for pipeline laying are proposed.(4)A potential distribution monitoring system for buried pipelines under AC interference has been established based on the law of AC interference.The software and hardware design of the modules in the monitoring system acquisition device has been carried out,and the monitoring system host computer has been programmed based on QT software.Real-time collection of potential distribution of buried pipelines during locomotive operation,historical query,and layout optimization during pipeline construction have been achieved.(5)Establish a simulation experimental platform for potential distribution of buried pipelines under AC interference.Through simulation experiments,the general rules of potential distribution of buried pipelines under unilateral and bilateral AC interference are obtained,and the correctness of the analytical model and mathematical simulation model is verified.The influence of different factors on the potential distribution of buried pipelines was verified through an experimental platform.This thesis has 60 pictures,13 tables and 90 references. |
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