Study On Measurement Technique Of High-Speed Railway Integrated Grounding

By laying the run-through ground wire along the two sides of railway, high-speed railway integrated grounding system fuses traction power supply return system, power service system, communication signal system, buildings, road bed, platform, bridges, tunnels, sound barrier and other electrical and electronic information system together, forming a huge-scale long-distance horizontal grounding system, which is an important guarantee of safe and stable operation of high-speed railway. There is little research information on the characteristic of high-speed railway integrated grounding system and no previous relevant standards which make the explicit regulation for the measurement method of high-speed railway integrated grounding system. It is important to carry out a study about high-speed railway integrated grounding measurement technology for the design, construction, acceptance, operation and maintenance of high-speed railway.This paper showed a field test work of high-speed railway integrated grounding system grounding resistance. It got adaptive measurement results of different wiring length in Wuhan-Guangzhou high-speed railway embankment section under 0.618 three-pole compensation method, reverse away method and angle method, and laid an experimental basis for the formation of independent high-speed railway integrated grounding measurement method. This paper established a numerical model of high-speed railway integrated grounding system, and got the relationship between the grounding impedance of high-speed railway integrated grounding system and various soil resistivity, run-through ground wire radius, run-through ground wire depth, run-through ground wire spacing, etc. This paper firstly proposed several key concepts such as influence scope, diffuser length, effective measurement spacing of high-speed railway integrated grounding system, obtained quantitative values of railway integrated grounding system properties and initially clarified the function mechanism of high-speed railway integrated grounding system.On the basis of Wenner four-pole soil resistivity measurement, this paper established a numerical model of the impact of high-speed railway integrated grounding system on soil resistivity measurement, studied the impact of parallel spacing between the measuring electrode line and the railway on the accuracy of measurement of soil resistivity under uniform soil and two-layer soil, and proposed parallel spacing between the measuring electrode line and the railway should not be less than the current electrode spacing in situ measurement of soil resistivity of high-speed railway.For the high-speed railway integrated grounding system measurement problem that the current electrode can not be arranged to several times the diagonal distance and voltage electrode arrangement is affected by the current field distribution, this paper established the grounding impedance numerical computation model of high-speed railway integrated grounding system under long current electrode and short current electrode, respectively studied the current field distribution and measurement error of high-speed railway integrated grounding system using the potential fall method, compensation method and reverse away method, calculated the quantitative impact of current electrode wiring length, soil condition and measurement method on the railway integrated grounding system grounding impedance measurement, proposed the reverse away method suitable for grounding impedance measurement of the railway integrated grounding system, including the electrode arrangement requirement and correction coefficient under different soil resistivity and current electrode wiring length. The measured results in the field test have good agreement with the analytical simulation results.For long-distance high-speed railway integrated grounding system and overhead ground wire influencing adjacent traction substation grounding measurement, this paper established a measurement and calculation model of a traction substation ground grid being not connected to the high-speed railway integrated grounding system, systematically calculated measurement error of substation grounding grid ground impedance using angle method under different electrode arrangement, different traction substation grounding grid size, different distance between integrated grounding system and grounding grid, different current electrode distance, different resistivity of uniform soil and two-layer soil, and proposed technical requirement for substation grounding grid ground impedance measurement using angle method when there was a high-speed railway integrated grounding system. This paper established a numerical model of grounding impedance of traction substation ground grid, and took two steps to achieve the calculation of grounding impedance of traction substation grounding grid with lightning shield line and integrated railway grounding system. A numerical example verified the accuracy of method and the correctness of the calculation model, and these can provide guidance for grounding impedance measurement of traction substation grounding grid.