Technical scheme for grounding of single-core cable especially for high-speed railway

Abstract

The invention relates to a technical scheme for grounding of a single-core cable especially for a high-speed railway, wherein the technical scheme is mainly suitable for a 27.5-kV single-core cable. According to the technical scheme, on the basis of characteristics of the high-speed railway traction power supply system, a 27.5-kV cable is divided into a plurality of units by combining a simulation result of a system model established by using a PSCAD / EMTDC, structural characteristics of a cable, and practical engineering information; and one end of the 27.5-kV cable in each unit is grounded directly and the other end is grounded by a protection layer voltage limiting device. The length of the cable of each grounding unit does not exceed 600m and a metal protection layer of an intermediate connector of each two grounding units is removed, thereby realizing independence of the grounding units. The cable grounding requirement at the two ends of the intermediate connector between each two grounding unit and the grounding requirement of the protection layer voltage limiting device match the grounding requirement of the 27.5-kV cable power supply loop.

Description

technical field [0001] The invention belongs to the technical field of cable grounding, and relates to the use technology of 27.5kV single-core cables, in particular to a special single-core cable grounding technical solution for high-speed railways. Background technique [0002] In recent years, high-speed, passenger-dedicated lines and intercity electrified railways have been rapidly constructed as links between important domestic cities. By the end of 2015, my country had completed 19,000 kilometers of high-speed railways that were officially in operation. In order to improve the safe and reliable power supply of high-speed trains, significantly save the land resources of traction power supply facilities, and significantly coordinate the urban landscape effect, 27.5kV single-core cables, as one of the core equipment and key technology platforms of traction power supply systems, have been widely used by my country's high-speed railways, especially High-speed railways with a...

AI Technical Summary

Problems solved by technology

Therefore, in order to ensure the personal safety of operation and maintenance personnel, the laying distance of single-circuit cable lines is very short, generally no more than 100 meters, which cannot meet the actual needs of the project in many cases

[0008] 3. In addition, for the solution where one end of the metal layer of the cable is grounded and the other end is suspended, if a short-circuit fault occurs in the cable line, an operating overvoltage or lightning strike occurs, a high induced voltage will appear at the suspended end of the metal layer, and the outer sheath of the cable insulation cannot withstand When this voltage is damaged, it will lead to multi-point grounding faults, so that the metal layer needs to carry a very large short-circuit current or circulating current. Once the current exceeds the current carrying capacity of the metal layer, it will also cause a large-area burning accident of the cable

Most of the existing engineering methods solve this problem by increasing the cross section of the metal layer of the 27.5kV cable, but it brings new problems, such as large cable diameter, difficulty in on-site construction, and high investment.

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