Electrified railway A railway that uses electric traction. Also known as electrified railway. Electric trains (trains and multiple units drawn by electric locomotives) run on electrified railways, and power supply system of electric traction (see power supply system of electric traction) which supplies power for electric locomotives and electric vehicles (hereinafter referred to as electric locomotives) is set along the railway. Railway with electric locomotive as the basic traction. It consists of two main parts: electric locomotive and power supply system. The power supply for electrified railways comes from the State Grid. The high-voltage alternating current of the State Grid was sent to the traction substation of the railway for the first time and sent to the catenary through the track. After the locomotive obtains the current from the catenary, it reduces the voltage for the second time in the locomotive and rectifies it into DC (or rectifies it in the traction substation) to drive the DC motor. The motor drives the locomotive axle to rotate, and the locomotive can tow the carriage forward. The electrified railway has developed rapidly and has become the most modern railway today. Its main features are: (1) high efficiency of electric locomotive. The efficiency of thermal power generation is four times that of steam locomotive; If hydropower is used to generate electricity, the efficiency is 10 times that of steam locomotive. (2) High power. At the end of the 20th century, the maximum power of electric locomotives can reach more than 10000 horsepower (the power of Shaoshan electric locomotive used in China is 5700 horsepower), which is four times that of steam locomotives and incomparable to diesel locomotives. Because of its strong traction ability, it can be used on railways with busy transportation, which can alleviate the tight transportation situation. (3) Fast acceleration and strong climbing ability, especially suitable for mountain railways. In addition, electric locomotives do not pollute the environment, drivers have good working conditions, and passengers can be free from the troubles of smoke and waste gas during the journey. Technical and economic advantages The electric locomotive motor car itself has no prime mover and fuel, and its specific power (power per unit weight) is higher. Compared with diesel locomotives and diesel motor cars, under the same or similar continuous traction (calculated by single axle), its continuous speed is more than doubled, and the trains with the same weight can reach higher rated maximum speed (or maximum running speed), and the constant power speed range is large, and the electric braking power is large, so its starting, braking, acceleration and deceleration performance is also high. The characteristics of electric traction, such as fast running and multi-pulling, can fully meet the comprehensive requirements of railway transportation to improve the running speed, increase the weight of trains and increase the running density, which is more conducive to: greatly improving the travel speed of passengers and the delivery speed of high value-added goods transportation; Organize efficient and fast heavy-haul direct transportation of bulk goods such as coal, building materials and grain; Give full play to the speed advantage, constantly introduce new transportation products, broaden the marketing scope of railway transportation, and enhance the competitive strength in the transportation market. In particular, the coordinated development of rail transit, expressway and air transport has attracted a large number of passengers in large and medium-sized cities and suburbs to change to high-speed and fast electric trains, which can obviously improve people's travel conditions, alleviate traffic congestion, reduce air pollution and save limited resources such as oil and land. This huge national economic and social benefit beyond the above-mentioned enterprise benefits has played an important role in awakening the governments and society of developed countries to re-understand the railway public welfare and obtain funds and support for railway development. Although the electrified railway has a large one-time investment, the electrified railway has a large traffic volume, high transportation income and low transportation cost, and the required investment can be recovered in a short time (depending on the traffic volume, it usually takes 5 to 10 years, and some only take 2 to 3 years). The reduction of transportation cost is mainly due to the direct use of external power supply, simple structure, few friction parts, low purchase cost and long service life, so the maintenance cost including energy cost, maintenance cost and depreciation cost is low; Rolling stock turnover is fast and equipment utilization rate is high; Passenger electric locomotives have few moving axles and light axle load, and the public works expenses increased by speeding up are also less; Air-conditioned passenger cars and refrigerated trucks will be connected to the grid for power supply day by day, which will save cost and capacity than adding power generation vehicles. The composition of modern electrified railway Electrified urban roads should include not only the power supply system of electric traction and electric locomotive, but also the telecontrol system for centralized monitoring of power supply facilities. Traction power supply facilities are distributed along the railway, and the operation and management are complicated. As early as the late 1950s and early 1960s, remote control devices were developed and adopted internationally. With the rapid development of electronic technology, especially the introduction of computer technology, the telecontrol device has gradually formed an increasingly perfect system (power supply system of electric traction subsystem). The functions of telecontrol system can be summarized as "four telecontrol", that is, remote control, remote communication, telemetry and remote adjustment. Using microcomputer telecontrol system can grasp the running state of power supply facilities in time, save manpower, realize unmanned operation, prevent false alarm of instructions and misoperation, improve the reliability of traction power supply and ensure transportation safety. The maintenance facilities of electrified railways should have a EMU operation and maintenance base that integrates locomotives and vehicles, in addition to the electric locomotive depot in the usual sense. The development of train operation control system is to adopt the combination of on-board and ground signals, with on-board signals as the main control mode. This requires the locomotive and EMU maintenance base to adapt to this situation of electromechanical integration, equip with corresponding maintenance equipment and technical force, and strengthen cooperation with the electric department. Since China Electrified Railway ABC was registered as this website on June 5438+ 10, 2003, it has been in contact with "Traction Power Supply Technology Forum", and made some replies to the topics of interest, learning a lot and benefiting a lot. I accidentally saw the "posting ranking" a few days ago, but I didn't expect to rank second. I also changed from a "beginner" to a "VIP". Thank you for your concern. These days, I sorted out the information and found a handout, which was the manuscript of a lecture on the safety management knowledge training course for leading cadres invited by Jinan Railway Bureau last summer. I wonder if anyone is interested. Sending a post today is a thank you to the webmaster. At the same time, I also take this opportunity to express my heartfelt thanks to my colleagues in Jinan Bureau for their warm hospitality! The content of the speech is divided into three parts: the basic knowledge of electrified railway, the relationship between traction power supply system and other departments and personal safety. Post the first part today. Please feel free to correct the fallacy. China Electrified Railway A B C Zhengzhou Railway Bureau L C W The first electrified railway in China was built in Baoji-Fengzhou section of Baocheng Line, with a total length of 9 1km. 196/kloc-0 was officially opened to traffic in August, and it has been more than 40 years. By the end of 2002, the mileage of electrified railway in China has reached 18336 km. Covering Zhengzhou, Beijing, Chengdu 1 1 Railway Bureau. With the construction of electrification project from Zhengzhou to Xuzhou, Jinan Railway Bureau will soon enter the operation of electrified railway and become a new member of electrified railway. China's electrified railways adopt power frequency single-phase AC traction system with rated voltage of 25kV. Traction power is electric energy. Traction power supply equipment converts the electric energy transmitted by the national power system into a form suitable for electric locomotives, and the electric locomotives complete the traction task. Therefore, traction power supply equipment and electric locomotive are the two main equipment of electrified railway, and other railway equipment and infrastructure should also adapt to it. I. Basic knowledge of electrified railway (I) Traction power supply system The electrified railway power supply system, also known as traction power supply system, mainly consists of traction substation and catenary. The traction substation reduces the transmission line voltage of the power system from 1 10kV (or 220kV) to 27.5kV, and sends the electric energy to the catenary through the feeder; Overhead catenary is erected along the railway, and the electric locomotive can obtain electricity from it after lifting the bow to traction the train. The catenary where the traction substation is located is equipped with a phase separation insulation device, and there is a booth between two adjacent traction substations, and the catenary is also equipped with a phase separation insulation device accordingly. The catenary (including feeder) between the traction substation and the sub-district pavilion is called the power supply arm. Traction power supply loop is a closed loop composed of traction substation, feeder, catenary, electric locomotive, track, return connection and grounding grid (traction substation), in which the current circulating is called traction current. Closing or disconnecting the traction power supply circuit will produce strong arc, which will cause serious consequences if it is not handled properly. Catenary, track loop (including earth), feeder and return line are collectively called traction network. The maintenance and operation of traction power supply equipment is the responsibility of power supply section, and the operation and scheduling of traction power supply system is the responsibility of power supply scheduling. Power supply dispatching is usually located in sub-bureaus and dispatching stations of railway bureaus. 1. The task of traction substation is to reduce the three-phase voltage of power system and feed it out in single-phase mode. The step-down is realized by traction transformer, and the transformation from three-phase to single-phase is realized by substation electrical wiring. Traction transformer (main transformer) is a kind of power transformer with special voltage class, which should meet the requirements of drastic changes in traction load and frequent external short circuits, and is the "heart" of traction substation. There are three types of traction transformers in China: three-phase, three-phase-two-phase and single-phase, so traction substations are also divided into three types: three-phase, three-phase-two-phase and single-phase. With the improvement of technical level, centralized monitoring telecontrol system has been popularized in electrified railways in China, and traction substations will gradually be unattended, and remote operation will be directly carried out by power supply dispatching. 2. OCS OCS is a special power line erected along the railway. The pantograph of electric locomotive receives current through sliding friction contact with it and obtains electric energy. Therefore, both of them should be kept in good working condition. The movement state of pantograph is very complicated and there are many influencing factors. In order to ensure good power supply, the catenary structure itself should be as follows: (1) The height of the catenary from the rail surface should be as equal as possible, and the relative positions of the anchor point and the mid-span and the center of the pantograph should meet the requirements; (2) Contact suspension should have relatively uniform elasticity and good stability; (3) Good insulation performance; (4) adapt to the change of meteorological conditions, keep the above characteristics, and there should be no major changes; (5) The catenary structure should be light, simple and standardized, which is convenient for construction, operation and maintenance; (6) standardized parts, easy to carry, corrosion resistant and high reliability; (7) The contact wire should have enough wear resistance; (8) The main circuit is unobstructed. (II) Catenary suspension mode Overhead catenary is mainly composed of contact suspension, supporting device, positioning device and pillar foundation. The first three parts are electrified and separated from the grounding body of the pillar (or other buildings) by insulators. 1, contact suspension Usually, contact suspension consists of carrier cable, hanging string, contact wire and compensation device, that is, chain suspension. The function of the compensation device is to keep the tension of the contact wire and the carrier cable unchanged when the ambient temperature changes. The anchorage mode of carrier cable and contact wire adopts compensation device called full compensation, and only contact wire adopts compensation called half compensation. The hanging string at the column adopts simple hanging string or elastic hanging string, which are simple chain hanging or elastic chain hanging respectively. At present, the main line of electrified railways in China mostly adopts fully compensated simple chain suspension, and the station line mostly adopts semi-compensated simple chain suspension. Suspension with only contact lines is called simple suspension, which is generally compensated, and is only used in a few occasions such as locomotive depot lines and special lines for factories and mines. The catenary is erected along the line, which is divided into single anchor sections to meet the mechanical stress requirements. The transition structure between anchor segments is called anchor segment joints, which are usually divided into insulated (four-span) anchor segment joints and uninsulated (three-span) anchor segment joints. The former is also called electric segmented anchor joint, and the latter is called mechanical segmented anchor joint. The electrical connection between anchor segments is completed by wires (three spans) or disconnectors (four spans). 2. Support device Support device is used to support contact suspension and transfer its load to pillars or other buildings, and its structure changes with line conditions. The interval is mainly wrist-arm structure; According to the number of tracks, line conditions, pillar positions and other factors, the station chooses soft-span, hard-span or wrist-arm structure, mainly soft-span, and the high-speed railway adopts hard beam; Large buildings such as tunnels and bridges (through bridges) should be designed according to specific conditions, and special structures should be adopted when necessary. 3. Positioning device The positioning device includes a positioner and a positioning tube, and its function is to ensure that the relative position of the contact wire and the pantograph is within the specified range and transmit the horizontal tension of the contact wire to the pillar. 4. Pillar Foundation Pillars are used to bear the load of contact suspension and supporting devices and fix the contact suspension at a specified height. There are two kinds of columns: steel columns and reinforced concrete columns. The former is built on reinforced concrete foundation, and the foundation is buried in subgrade; The latter is directly buried in the subgrade. Bridges (deck bridges) usually use steel columns, and their foundations are reserved on piers. The column is also equipped with a grounding device, which is connected with the track loop and plays a protective role. The lower anchor column is also provided with a compensation device and a cable device. (3) catenary power supply section In order to ensure safe power supply and flexible use, the catenary is structurally provided with a power supply section. As mentioned above, the phase-separated insulation device installed on the catenary where the traction substation and the sub-district pavilion are located is a phase-separated electrical section; The electrical sections set in the same power supply arm are in-phase electrical sections, such as between sections and stations (vertically), freight lines, loading and unloading lines and section pipelines in stations (horizontally). In-phase electrical subsection structure is a four-stage anchor section joint, or a subsection insulator+three-stage anchor section joint structure is adopted. The structure of split-phase electrical sectioning was originally an eight-span (two four-span overlapping) anchor section joint, and later it was changed to a split-phase insulator and a three-span anchor section joint. In recent years, with the continuous improvement of train speed, the articulated split-phase structure of anchor section has been gradually adopted in speed-up section and high-speed section because of its advantages such as good elasticity, small hard points and smooth pantograph transition. It must be pointed out that when the electric locomotive passes through the phase-separated insulation device, there must be no power supply, that is, the main circuit breaker is disconnected before passing, and then closed after slipping, otherwise it will cause strong arc, short circuit between phases and even burn the catenary clue. (IV) OCS power supply mode All electrified railways in China adopt unilateral power supply mode, that is, when the traction substation supplies power to the OCS, the OCS of each power supply arm only obtains power from one end of the traction substation (the power supply on both sides is bilateral, which can increase the network voltage at the end of the OCS, but it is not adopted because of its large fault range and complex relay protection device). The double-track section can be connected to the upstream and downstream catenary through the partition pavilion to realize "parallel power supply", which can appropriately increase the terminal network voltage. When the traction substation fails, the adjacent substations realize "cross-regional power supply" through the partition pavilion. At this time, the power supply range is expanded and the network voltage is reduced. Usually, it is necessary to reduce the number of trains or traction times to maintain operation. 1, direct power supply mode As mentioned above, electrified railway adopts power frequency single-phase AC electric traction system, and single-phase AC load generates alternating electromagnetic field in the space around catenary, thus causing certain electromagnetic interference to nearby communication facilities and radio equipment. When the early electrified railways in China (such as Baocheng Line and Yang 'an Line) were built, they were located in mountainous areas and the local communication technology was underdeveloped. Coaxial cable with high shielding performance is used in railway communication, and the electromagnetic interference generated by catenary is very small, so special protective measures are not needed. Therefore, the above-mentioned unilateral power supply mode is also called direct power supply mode (TR power supply mode for short). With the development of electrified railways to plains and big cities, the contradiction of electromagnetic interference is becoming increasingly prominent. Therefore, different protective measures are taken in the power supply mode of catenary, resulting in different power supply modes. AT present, there are so-called BT, AT and DN power supply modes. As can be seen from the following introduction, these power supply methods all have the same feature, that is, an additional conductor with the same height as the contact suspension is suspended on the field side of the catenary pillar. In electric traction, the current passing through the additional conductor and the traction current passing through the catenary are theoretically (or ideally) equal in magnitude and opposite in direction, so that the electromagnetic interference generated by them cancels each other out. But it is actually impossible, so different power supply methods have different protection effects. 2. Power supply mode of current absorption transformer (BT) In this power supply mode, a current absorption transformer (variable ratio 1: 1) is installed on the catenary at regular intervals, and its primary side is connected in series with the catenary, and its secondary side is connected in series with the return line (referred to as NF line for short, installed on the field side of the catenary pillar, with the same height as the contact suspension). Between every two current absorption transformers, Due to the earth backflow and the so-called "half-level effect", the protective effect of BT power supply mode is not ideal, the catenary structure is complex, and the current collection conditions of locomotives are deteriorating, while the "suction-back" device has been rarely used in recent years. 3. When the power supply mode of autotransformer (AT) adopts AT power supply mode, the output voltage of the main transformer of traction substation is 55kV, which supplies power to catenary via AT (autotransformer, the transformation ratio is 2: 1), one end of which is connected to catenary, and the other end is connected to positive feeder (referred to as AF line for short, which is also on the field side, with the same height as contact suspension), and the tap is connected to rail. AF line and NF line have the same function in BT power supply mode, which plays an anti-interference role, but the effect is better than the former. In addition, there is a protection (PW) line under the AF line, which plays the role of protection tripping when the catenary insulation is damaged, and also has the functions of anti-interference and lightning protection. Obviously, the catenary structure of AT power supply mode is also complicated. There are two groups of additional wires hanging on the field side, the voltage of AF line is equal to that of catenary, and the PW line also has a certain potential (about several hundred volts), which increases the fault probability. When the catenary fails, especially when the pole is broken, it is even more troublesome, and it is difficult to repair and restore, which greatly interferes with transportation. However, due to the high feedback voltage of traction substation, the distance can be doubled and the terminal network voltage can be appropriately increased, which has its advantages in areas with weak power system network. 4. Direct supply+reflux (DN) power supply mode This power supply mode is actually a streamlined direct supply mode. NF line is connected to the rail at regular intervals, which not only plays an anti-interference role, but also has the characteristics of PW line. Because there is no current absorption transformer, the network voltage is increased and the catenary structure is simple and reliable. It has been widely used in recent years. To sum up, the early electrified railways all used direct power supply. In order to avoid and reduce the electromagnetic interference to the external environment, BT, AT and DN power supply modes are developed. From the perspective of protection effect, AT mode is superior to BT and DN mode, and DN mode is the simplest and most reliable from the perspective of the structural performance of catenary. With the rapid development of communication technology and the wide application of optical cables, the anti-interference performance of communication facilities and radio equipment has been greatly enhanced. Considering that the operation reliability of catenary is very important to the safe operation of electrified railway, DN power supply mode is generally considered as the first choice. In areas with weak power system, after economic and technical comparison, AT power supply mode can be adopted, and BT power supply mode should be used as little as possible or not. In my opinion, this is a general view summed up in the practice of the development and application of electrified railway power supply mode in China in the past 30 years, and it should also be tested in the future practice, constantly summarized and improved. (V) Introduction of electric locomotives Most of the electric locomotives used in electrified railways in China are SCR electric locomotives, which are widely used because of their simple structure, good traction performance, reliable operation, convenient maintenance and high economic and technical indicators. When the electric locomotive is working, the pantograph obtains high-voltage single-phase alternating current energy from the catenary, which is converted into low-voltage direct current for the traction motor after being stepped down by the transformer and rectified by the rectifier. At present, domestic electric locomotives are mainly SS (Shaoshan) type, and SS 1, 3, 4, 6, 6B, 7 and 7B types are both passenger and freight. In recent years, with the speed-up of trains and the development of high-speed railways, SS7C, 7D, 7E, SS8 and SS9 passenger electric locomotives and DJ passenger transport have been developed. In addition, China has introduced electric locomotives from France (6Y, 6G, 8K), Japan (6K), Germany (DJ 1) and the former Soviet Union (8G). Here is a brief introduction to the basic knowledge of electrified railways. According to the Reply of the Ministry of Railways on the Preliminary Design of Zhengzhou-Xuzhou Electrification Reconstruction Project, the traction power supply system of Zhengzhou-Xuzhou electrified railway managed by Zhengzhou and Jinan Railway Bureau adopts telecontrol devices; The traction substation of Wenzhuang in Jinan Bureau adopts single-phase substation, and the main transformer is 220kV single-phase traction transformer. Putian traction substation of Zhengzhou Bureau adopts three-phase substation, and the main transformer is 1 10kV three-phase Y/δ connected with traction transformer; Other traction substations between Zhengzhou and Xuzhou adopt three-phase and two-phase substations, and the main transformer is a newly developed 1 10kV three-phase V/V traction transformer. The catenary adopts fully compensated simple chain suspension (main line) and semi-compensated simple chain suspension (station line), and the split-phase insulation device is anchored; The station yard between Liu Zhuang and Beidongzha of Jinan Railway Bureau and Shangqiu West and xinglong village of Zhengzhou Railway Bureau adopts the hard beam scheme to meet the requirement of the maximum train speed of 200km/h; The power supply mode is DN mode; The passenger locomotive is SS9 and the freight locomotive is SS4. Main courses: electrical and electronic technology, mechanical drawing, mechanical foundation, C language programming, microcomputer principle, motor driving foundation, converter technology, mechanical vehicles, traction motors and electrical appliances, locomotive electronic circuits, brakes, locomotive control and wiring, locomotive traction and application, three types of equipment, urban rail transit and subway, railway power supply system. Employment orientation: After graduation, graduates can engage in technical and production work in the operation, management and construction departments of electrified railways, urban rail transit, electric locomotive production enterprises and general factories and mines. Employment group: 1. Engaged in electric power dispatching of electrified railway enterprises. 2. Engaged in the production, operation, maintenance and management of power distribution stations, catenary and other departments. 3. Engaged in the production and operation management of urban rail transit traction power supply specialty. 4. Engaged in the construction and management of railway and urban rail transit traction power supply projects. 5. Engaged in the overhaul and maintenance of electrified railway power supply equipment. 6 senior management and technical personnel engaged in construction, operation and maintenance in various power enterprises.