Research On Lightning Impulse Charactiristics On High-Speed Railway Integrated Grounding System

With the rapid development of high-speed railways in China, the total mileage of electrified railways has ranked the second place in the world. On the other hand, a lot of high-speed railways, which have been built or under construction or planned to be constructed, would have to go across the intensive lightning occurring areas. Lightning strikes have become a serious risk to the railway safe operation in our country. Yet researches on lightning grounding protection in the traction power supply system are only a few.Although many scholars at home and abroad are in the study of transient behavior of the power supply grounding system, the high-speed railway integrated grounding system is different from the grounding grid and grounding electrode in the electric power system. Firstly, the high-speed railway integrated grounding system is far more complicated, with the power supply system, traction power supply returning system, signaling system, communication and electronic information system, and the apparatus in buildings and stations needed to be grounded all connected together by the connecting ground wire. Secondly, the high-speed railway integrated grounding system is of great extensibility. The grounding connection wire stretches over several hundreds of kilometers, quite similar to an infinitely long conductor. Therefore, A more accurate and reasonable calculation model of high-speed railway grounding system based on electric field theory combined with circuit theory is required to be established. And the electromagnetic properties and leakage current law of the grounding conductor is required to be analyzed. All of the researches have great significance for fast and accurate high-speed railway integrated grounding system design, the safe operation of the existing grounding system as well as the personnel protection.In this thesis, firstly, the influencing factors in the impulse grounding of the high-speed railway integrated grounding system have been analyzed. And the effect of impulse grounding under different parameters has been obtained. Then, the key facility of the high-speed railway integrated grounding system---the connecting ground wire---has been studied with modeling. The improved circuit model of the connecting ground wire has been built by ATP-EMTP. Together with the spark discharge effect in the transient electric field, the features about current transmission and current leakage have been measured. And the earth potential around the connecting ground wire has been calculated by applying the electrical axis method. The safe distance between grounding terminals along the railway has been made clear. What’s more, the electromagnetic radiation from the lightening to the railway at different position and at different speed of the return stroke has been calculated. And the coupling model between two rails has also been established. Meanwhile, the impact coupling parameters as well as the railway Induced Voltage and Induced Current have been calculated by applying the transmission line theory and the Agrawal model. So the sphere of the influence that lightning has on the railway is found out. In the last part of the thesis, simulating calculations from whole to part of the leakage current characteristics and potential distribution, which occur in the catenary pillar terminals as well as in the integrated grounding system, have been carry out by using CDEGS and Ansoft software. The previous solution has been further validated by the results of the calculations, which also provides reference to the design and construction of railway integrated grounding system.