The Rail Potential And Surface Potential Of Integrated Grounding System In High-Speed Railway

The high-speed railway integrated grounding system, which not only provides the reference potential to the traction power supply system to ensure the safety of rail potential in a certain range, but also absorbs traction return current to realize traction power closed loop and considers the unity of strong and weak electronic, is an important guarantee for the safe and stable operation of the high-speed railway. With the increasing of the traction power and the density of train, traction return current brings new challenges of distribution in integrated grounding system and rail potential rise. Integrated grounding line and contact network are the backbone of integrated grounding system. The laying of integrated grounding line and contact network is hidden work and they are buried under ground all year round which are prone to corrosion, breakage and other defects. Detection directly need a large number of complex processes such as excavation and buried back and can easily result in a secondary damage of integrated grounding line and contact network. Once integrated grounding system defects or damages, rail potential and the reference potential across the board will rise, which is a risk of site personnel and causes great interference to communication systems.To solve the problems, this paper analyses the rail potential, grounding grid surface potential and integrated grounding line surface potential deeply and obtains distribution law and the influencing factors of them, providing foundation to solve the high rail potential and fault diagnosis of comprehensive grounding system. Firstly, according to the characteristics of return current in AT short circuit, the process of return can be divided into divergence process in line and collection process at substation. The distribution relationship in different path of integrated grounding system was analyzed and the divergence coefficient and collection coefficient was defined. Then, based on the analysis of the divergence coefficient, the rail potential influence with different factors was analyzed with the method of circuit analysis, and the rail potential influence with locomotive location and quantity was simulated. And then, according to the field-circuit theory the formation mechanism of surface potential was analyzed. Based on the simulation software CDEGS, the grounding grad module of integrated grounding system was built, and the influence factors of grounding grid’s surface potential was studied, and the distribution characteristics of grounding grid’s surface potential when it happened deletion or corrosion was researched. Finally, integrated grounding line’s surface potential was analyzed according to the theory of field-circuit. The effects of different factors to integrated grounding line was simulated and it is explicated that the defect location and the degree of defect can be judged with the integrated grounding line’s surface potential, which provided a reference for repair and maintenance.According to the above research, the important sorting of rail potential influencing factors is obtained. Rail potential distribution law of the locomotive in complete transversal connecting point, incomplete transversal connecting point and non-complete transversal connecting point and rail potential distribution law in different position combinations of two locomotive are summarized, providing the reference for the implementation of reducing rail potential measures. In addition, according to the characteristics of the surface potential distribution of contact network and integrated grounding line, the method of the judgment of the defect area with the surface potential and the diagnosis of the defect degree is summarized, providing foundation for the health diagnosis of integrated grounding system and the formulation of maintenance strategy.