| In the wake of the increase in operating speed of high-speed railway,the traction load has been enhanced and the current is continuously consumed during high-speed operation.The electromagnetic interference in parallel cables along the railway line that originates from the traction power supply system in high-speed railway has been increasingly apparent.This study aims to study the electromagnetic interference mechanism of high-speed railway traction power supply system on parallel cables,to analyze the influencing factors and working patterns in different sections,and to access the protective measures to reduce the electromagnetic interference to parallel cables.The power cables parallel to high-speed railway as research objects.The research was conducted from the theory of electromagnetic coupling,the factors and characteristics of electromagnetic interference in different sections,and the engineering protection methods.The work has been summarized as follows:First,the research status of electromagnetic coupling theory in power system and traction power supply system was summarized,the research background and significance of this subject were expounded,and the structure and the characteristics of high-speed railway traction power supply system were introduced.Second,the mechanism of electromagnetic coupling between high-speed railway traction power supply system and parallel cables including capacitive coupling,inductive coupling and resistive coupling was analyzed.Based on the theory of rail current distribution and the ground potential near the point electrode,a formula for calculating the induced voltage of parallel cables considering rail leakage current was derived,and then simplified by the shielding factor.A formula for calculating ground potential along the traction power supply system of highspeed railway was also derived.The results showed that the electromagnetic interference of parallel cables was related to the traction load,the spatial position of parallel cables and highspeed rail,the parameters of parallel cables and the parameters of soil structure.Third,the CDEGS software was used to establish electromagnetic coupling models of high-speed railway traction power supply systems to parallel cables in different sections,and the validity of the model was verified at the aspects of current distribution and coupling relationship.The factors and characteristics of electromagnetic interference from high-speed railway traction power supply systems to parallel cables concerning traction load,parallel cable parameters,soil structure parameters,short circuit faults,viaducts and tunnel structures,have been studied.The results showed that the aforementioned factors all influenced the degree of electromagnetic interference on the parallel cables,which should be considered in engineering design and operation.The electromagnetic interference shielding effect of highspeed railway in viaduct section and tunnel section is better than that in subgrade section.Finally,the induced voltage of the parallel cables in different grounding modes was analyzed,including grounding at both ends,grounding at one end,grounding at the midpoint,and cross-bonding grounding.The grounding methods of parallel cables at different lengths were proposed.The distance between high-speed railway and normal speed railway was studied,and the engineering protection methods in design,construction and operation were proposed.The results showed that with the length of the parallel cable increases,the grounding methods should be conducted in sequence of grounding at both ends,grounding at one end,grounding at midpoint,and cross-bonding grounding.And in engineering design,the protection distance between high-speed railway and normal speed railway should be set according to different cable lengths. |
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