1, station power supply. Large stations have power plants or special power supply lines for high-voltage transmission, and the high and low voltages of various electrical equipment in the station are supplied by power supply transformers, which is as easy to understand as the power supply bureau supplying power to urban areas, so I won't say much here.
? It should be noted that the stations along the railway supply power to each station through the through power supply line of the whole railway.
2, ordinary train power supply. The power supply of electric traction locomotive is provided by power supply stations along the way through catenary, which is described in detail in the high-speed rail part. Due to the rapid development of railway modernization in China, passenger trains have been basically replaced by new air-conditioned passenger trains. The air conditioning system, lighting system and heating system of trains and vehicles consume a lot of electricity. So how to supply power? Passenger trains are powered by power supply trains.
What is train power supply? At present, passenger trains consume a lot of electricity, and some of them are drawn by diesel locomotives instead of electrified railway lines. In order to solve this problem, a power supply car was added to the passenger train. Electric power is generated by the generator driven by the internal combustion engine, and the electric power is supplied to each car through cables, so the passenger train uses the electric power provided by the power supply train.
3. Passenger dedicated line and high-speed rail power supply system. High-speed trains on passenger dedicated lines are bullet trains with a speed of 300 to 350 kilometers per hour; The passenger speed is 200 to 250 kilometers per hour. What is the essential difference between the two? High-speed rail uses each wheel as the driving wheel, while passenger dedicated line trains use the front wheel set, middle wheel set and rear wheel set as the driving wheels. Because each set of power wheels needs to synchronize each job and put forward higher technical requirements, it is also called EMU.
? We know that the high-speed rail has no special headstock, that is, a group of bullet trains has a power supply system, so the power supply system of each train supplies power to each train through the railway catenary along the way.
? The electrified power supply principle of high-speed rail is the same as that of ordinary rail, but the requirements of high-speed rail are more stringent. Due to the increase of train speed, the pantograph on the upper part of the train and the catenary on the upper part of the locomotive need reliable contact to obtain electricity normally. The faster the speed, the greater the impact, just like a small insect sitting on a truck will hurt when it hits its face. Therefore, the catenary of high-speed rail is straight and requires high ride comfort.
? We know that alternating current is three-phase electricity, so there is only one line on the overhead catenary of electrified railway. What's the matter? Please take a look at the structure and working drawing of the electric locomotive as a simple understanding:
? Electric locomotive: I see. Briefly describe the catenary first. Catenary consists of supporting parts, namely, pillars and wrist arms. The structural part of catenary is the suspension part between the lower part of the wrist arm base of carrier cable and the contact line, including carrier cable and contact line. Catenary is divided into various anchor sections, whether in the station or in the driving section. In order to prevent the contact line from being affected by temperature, it is tight in winter and loose in summer, and heavy objects are hung on both sides of each anchor section. In order to prevent the contact line from moving, an intermediate anchor is assumed. In order to prevent the contact wire from grinding the pantograph out of the groove, the contact wire is pulled out left and right to form a sawtooth shape, which is also the positioning pull-out value.
? In order to isolate the whole power supply network from each power supply station and each phase of alternating current, subsection and phase isolation insulators are installed at the parts that need isolation. So when you take the high-speed train, the lighting of the train will be interrupted for a period of time, which is caused by the contact between the pantograph and the insulator. Therefore, there will be a warning sign "No Double Bows" in this section to prevent short circuit caused by the separation of each phase of each power supply from alternating current.
Electrified railways have many forms of power supply. Let's talk about the power supply process in the form of autotransformer (AT) power supply:
Power supply mode of autotransformer in electrified railway
When the AT power supply mode is adopted, the output voltage of the main transformer of the traction substation is 55kV, and the power is supplied to the catenary through AT (autotransformer, transformation ratio is 2: 1), and one end of AT is connected to the catenary, and the other end is connected to the positive feeder (referred to as AF line for short, also on the field side, with the same height as the contact suspension), and the tap is connected to the 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.
What is a switching station?
The so-called switching station refers to the distribution station that uses switching equipment to open and close the circuit without voltage conversion. Generally, there are two incoming lines, and then they are fed out in multiple ways to supply power to each section of the catenary of the hub station. Both the incoming line and the outgoing line pass through the circuit breaker, so as to realize the flexible operation of each section of the catenary when the power supply is stopped. Due to the short circuit fault of the contact line of the circuit breaker protection, the scope of accidental power failure can be reduced.
2. What is a partition pavilion?
The booth is located in the middle of two traction substations, which can make adjacent catenary power supply sections (the upper and lower power supply arms of the same power supply arm or the two power supply arms of two adjacent substations) work in parallel or independently.
If a section of catenary on both sides of the substation has a short circuit fault, the feeder circuit breaker of the traction substation and the circuit breaker of the substation can automatically trip under the action of relay protection, and the catenary of the fault section will be cut off, but the catenary of the non-fault section will still work as usual. In this way,
The scope of the accident was reduced by half.
3. What's in the college?
When the traction network adopts AT power supply mode, an autotransformer AT is set every 10km along the railway, which is called AT station.
The autotransformer is connected between the catenary (T) and the positive feed conductor (AF), and its point is connected with the rail (R) and the protective wire (PW) erected on the same pole of the catenary line.
3. What's in the college?
When the traction network adopts AT power supply mode, an autotransformer AT is set every 10km along the railway, which is called AT station.
The autotransformer is connected between the catenary (T) and the positive feed conductor (AF), and its point is connected with the rail (R) and the protective wire (PW) erected on the same pole of the catenary line.
I hope I can help you.