Method Of Defect Diagnosis In Integrated Grounding System Of High-Speed Railway

With the increasing of the traction power and the density of train, the new requirements include the rail potential rising, the safety of devices and person along the rail line are put forward in the operation and maintenance in high-speed rail way. And it also brings the higher request to integrated grounding system. Integrated grounding system mainly contains the grounding grid in transformer substation and integrated grounding line (IGL) along the railway. IGL, which is the core of integrated grounding system, not only connects the electrical equipment along the railway to provide grounding potential to different kind of protections, but also absorbs traction return currents to realize closed loop and lower the rail potential. It’s an important guarantee for the safe and stable operation of the high-speed railway. IGL is copper conductor, and easily be stolen by criminals. Besides, lashed by different traction current, fault current and lighting current, and buried underground with the influence of water, air and the salts, IGL is vulnerable to corrode even fracture. Once the integrated grounding system goes fault, would cause the rail potential goes higher, lightning current drainage issue, and cause serious interference to communication facilities along the railway, would influence the normal operation of the line and even threaten the safety of person. Detecting directly need a large number of complex processes such as excavation and buried back and can easily result in a secondary damage. So, how to detect the fault area of the integrated grounding system without digging and not influence the normal operation of the line, is a problem to research.To solve the problem above, this paper based on the features of the high-speed railway integrated grounding system, use the method of electric field and circuit, analyze the normal and fault state’s surface potential and surface magnetic field distribution of the IGL. When current is injected to subgrade integrated grounding system. And build a reflux model of an AT section by electromagnetic grounding simulation software CDEGS, simulate the surface potential and magnetic field distribution of IGL in normal and fault state, the simulation results show that both two electrical quantity could response the fault accurately. Compare the two method’s advantages respectively from error, applicability and feasibility, then, summarize a method to locate the fault area of IGL in high-speed railway; to verify the applicability in different rail conditions, build the model of the bridge integrated grounding system, complete the simulation under the normal and fault conditions; add catenary mast to simulation model, research the interruption of lightning current and short-circuit current and improve the method.