Power cable is an important part of railway power engineering construction. In order to meet the design and construction standards, all aspects of railway power engineering construction should be done well to ensure the quality of railway power engineering construction. This paper introduces the power supply lines and construction of high-speed railway power system, analyzes the problems existing in railway power engineering construction, and puts forward corresponding solutions, hoping to play a certain guiding role in railway power engineering construction.
Key words: railway power engineering; Power cable; Engineering construction; Construction quality; railroading
In recent years, China's investment in railway construction has increased rapidly, which has greatly promoted the development of railway power engineering construction technology and the improvement of engineering quality. However, in the actual construction process of railway power engineering, there are also some unsatisfactory places, especially some outstanding technical and management problems, which have a very adverse impact on the construction quality of railway power engineering and the safe power supply of power supply system. In this case, it is necessary to know the power supply principle of railway power system and the construction of railway power engineering in detail, find out the fundamental problems, put forward reasonable solutions, completely solve the problems existing in railway power engineering construction, improve the construction quality of railway power engineering, and ensure the safe and normal power supply of power supply system. As the proportion of cable lines is gradually increasing, the following will focus on the construction of power cables and related issues.
1 brief introduction of railway power supply line system
The electric energy obtained by the railway system is transmitted from the power plant to the substation of the railway power supply system through boosting, and the substation reduces the voltage or current to a range suitable for the operation of the railway train, and then transmits it to the train through overhead lines or power cables. Therefore, overhead lines and cable lines are the core parts of railway power supply line system. Here is a brief introduction to the characteristics of these two power supply lines:
1. 1 overhead line
Overhead lines are transmission lines that use insulators to fix wires on vertical poles to transmit power. Overhead lines are mainly composed of transmission lines, insulators, poles and grounding devices. Compared with cable lines, it has the advantages of low cost, short erection time and convenient maintenance. However, overhead lines also have obvious shortcomings. Due to exposure to the external environment, they will be affected by various meteorological conditions, such as temperature changes, rainstorm attacks, hail, lightning, etc., which will cause serious damage to the protective layer of overhead lines and even power failure in severe cases.
1.2 cable
Cables usually consist of wires, insulation layers and protective layers. Cable lines are generally used in areas where overhead lines are difficult to set up, such as special areas such as cities and tunnels. Compared with overhead lines, cable lines have the advantages of high power supply reliability, no need to occupy ground space, no need to erect poles, and saving wood and cement. In addition, due to the high reliability of the cable line, its operation, maintenance and overhaul are very simple. However, cable also has obvious shortcomings. First of all, cables are expensive. In addition, the cable joint construction technology is complex and prone to failure. After laying, it is very difficult to repair the cable.
2 Brief introduction of railway power engineering construction technology
In power transmission, the proportion of power cable is gradually increasing. With the sustained and rapid development of domestic economy, the power cable industry is developing rapidly, especially the railway power supply system. Therefore, in the railway power engineering construction, the utilization rate of power cables is increasing year by year. The following mainly introduces the construction technology of power cables in the railway power engineering construction.
2. 1 Construction and laying methods of railway power cables
2. 1. 1 subgrade section. In ordinary subgrade areas, power cables should be laid along the reserved grooves on both sides of the track, and when crossing the track, the cables should be protected by steel pipes. In addition, the transition zone between subgrade section, bridge section and tunnel section should be provided with transition sections, which should also meet the requirements of cable bending radius.
2. 1.2 Bridge section. In the bridge area, power cables should be laid along the reserved grooves on both sides of the bridge rail, and serrated notches should be reserved for the power cables to be led up or down on the bridge. When the cable is led out from the cable trough or under the bridge, the led-out cable shall be laid on the cable tray on the pier.
2. 1.3 tunnel section. In the tunnel section, the power cable should be laid along the reserved grooves on both sides of the tunnel track, and the tunnel lighting room should be provided with an ultra-long cavity that meets the requirements of the complete radius of the cable. In addition, a set of rail-crossing steel pipes should be set near the entrance and exit of the tunnel and the cavern in the tunnel to ensure that the cable is not damaged.
2. 1.4 station section. In stations and sections, power cables are used for high and low voltage lines, which should generally be laid in ditches along the way, and some sections can be directly buried with steel pipes for protection.
2.2 Railway power cable laying construction technology
2.2. 1 Directly Buried Laying Construction Technology. Directly buried laying construction can be divided into three parts, namely trench excavation, directly buried cable laying and filling. Dig a ditch. Main requirements: First, the depth of the trench from the ground shall be at least 0.7m, and the trench shall be deepened to 1m when crossing roads, at least 1.2m when crossing agricultural land, and at least1m when the cable power supply voltage exceeds 35kV; Second, when crossing urban rail transit, cables should be installed in accordance with the specifications and corresponding protective measures should be taken; Thirdly, the turning radius of the groove should meet the requirements of the bending radius of cable laying; Fourthly, when the trench is dug in the hillside area, it should be dug into a cycloidal curve to facilitate the laying of cables and reduce the possibility of cables being washed away by floods. Directly buried cable laying. Before laying directly buried cables, the construction site and cables shall be inspected to avoid damaging cables. When laying, the cables shall be placed neatly without crossing, and the cables shall be covered with cable protection plates. Corresponding protective measures should be taken for the cable lead-out section, and the cable joint should be marked. After laying, the cable end must be sealed to prevent the cable from being damp. Backfill the soil. The soil used for backfilling should not corrode the outer layer of cable and contain no hard impurities such as pebbles. After filling, it should be compacted, and corresponding warning signs should be set above the soil layer of directly buried cables.
2.2.2 Cable and pipeline laying construction technology. Before laying the cable, it should be checked that the core wire of the cable should meet the requirements of non-magnetic materials, and there should be no sundries in the pipeline used for laying. When the cable passes through the pipeline, it will not cause cable damage. When laying cables, the traction force and lateral pressure on cables should meet the requirements of different cable qualities, and the bending radius of cables should meet the requirements of cable bending radius. Corresponding protection measures should be taken at cable joints, bends and other places that are easy to cause cable damage. When the cable voltage exceeds 1 10kV, the lateral pressure at the bend should not exceed 3kN/m (unless otherwise specified by the cable manufacturer). After cable laying, the cable shall be fixed on the cable bracket according to regulations, and the cable in the pipeline shall be sealed and marked at the cable joint.
3 problems existing in the construction of railway power engineering
3. 1 Pipeline and cable laying problem
Pipeline cable laying mainly includes unqualified selection of pipeline raw materials, unqualified pipeline protective layer, unqualified cable bending and line layout. Among them, the problem of unqualified selection of piping raw materials is that there is no zinc plating where zinc plating is needed, and no metal tube is selected where metal tube is selected; The problem of unqualified management protective layer is that the lack of supervision in the process of burying will lead to pipeline cracking due to insufficient protective layer, and even block the pipeline in serious cases; The problem of cable bending is that the minimum bending radius of the cable is not considered when designing the groove, which leads to inductance phenomenon when large current passes through the cable and may damage the circuit system. The problem of line layout is that the sundries falling into the pipeline cannot be removed when buried, which may cause the cable to block or scratch the outer layer when entering the pipeline.
3.2 Railway Cable Erection Problems
The main problem of railway cable erection is that some construction units use inferior products for personal gain when erecting cables, and the related cables are used at will regardless of the system. In addition, when connecting cables, the cables at both ends are connected at will, which will make the cables difficult to meet the use needs, cause chaos in the power system, and even lead to paralysis of the whole power system due to cable quality problems, resulting in serious consequences. 3.3 Other problems In the construction of railway power engineering, due to the lack of professional quality and safety awareness of some construction personnel, some construction problems are prone to occur during the construction of railway power engineering, such as: the construction personnel did not set the distribution box and junction box according to the correct coordinates of the drawings; The deviation between lamp position and ceiling fan hook box is large; The boxes in the column are not neatly placed, and the boxes are not firmly placed. When there is vibration, their positions move easily.
4. Suggestions on the problems existing in railway power engineering construction.
4. 1 Suggestions for laying pipelines and cables
Before construction, we must strictly review the construction drawings, carefully check possible mistakes and omissions, and correct unreasonable places in time, especially the bending radius of cables, paying special attention. In addition, the design concept should be fully integrated with related disciplines, and the construction difficulties caused by professional problems should be reflected to relevant departments in time. In the process of construction, it is necessary to supervise and guide key construction links to prevent construction personnel from cutting corners. In addition, pay attention to the selection of pipes and cables to ensure that the selected materials can meet the requirements of the whole construction. The purchased materials should be counted in detail to prevent inferior materials from entering the construction site.
4.2 Suggestions on Railway Cable Erection Construction
When laying cables, the cables shall be arranged neatly and shall not cross. In addition, corresponding protective measures should be taken in the cable lead-out section, and the cable joints should be marked. Finally, after the laying is completed, the end of the cable needs to be sealed to prevent the cable from being damp. After the phased construction is completed, a special quality inspection team should be arranged to inspect and evaluate the construction quality, check whether the cables are connected, and prevent errors in the construction process, especially the wrong connection of cable joints and cable disconnection. 4.3 Other construction suggestions In order to avoid problems caused by the lack of professional skills of construction workers, enterprises should pay attention to the management of construction. Construction enterprises should systematically train construction workers, improve the quality of on-site construction workers, require construction workers to carry out construction operations in accordance with relevant rules and regulations, establish a reasonable system in which old employees lead new employees to carry out construction operations, and integrate theory with practice, so that all construction workers can develop good construction habits. In addition, the corresponding punishment system should be formulated to punish employees who violate the construction specifications. The appointment of technical managers must be strict and cautious, and technical managers must have sufficient experience in construction management. Finally, when the project is delivered, we must do a good job in quality and safety inspection to ensure the monitoring during the construction process and the control after the project is completed.
5 conclusion
In a word, railway power engineering construction is an important part of the whole railway construction, and we must attach great importance to possible problems in construction projects. Preventing and solving these problems is of great practical significance to the construction of the whole railway power engineering.
References:
[1] Xue Kaijun. Problems and Suggestions in Railway Power Engineering Construction [J]. Technology and Market, 20 14, (6).
[2] Snow White. Discussion on construction technology of high-speed railway power engineering [J]. Theoretical research on urban construction (electronic version), 20 12, (14).
Pang Jiuzong. Analysis on construction technology of high-speed railway power cable [J]. Chengtie Science and Technology, 20 16, (2).
[4] Jiang Baohua. Analysis on the Problems and Countermeasures in Railway Power Engineering Construction [J]. China Science and Technology, 20 16, (18).
[5] Cory Lee. On the problems and suggestions in railway power engineering construction [J]. Engineering Technology (full text), 20 16, (5).
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