Substation, partition office, AT Office

Open and closed locations

 

When a branch of the traction network is introduced at the sub-section post, a control place with protective jump case breaker and other facilities is set up to ensure safe and reliable power supply without affecting the Power traction. It is usually located at the hub station, the compilation site, the power Locomotive Depot, And the return section. In a multiline AT traction network with a large power supply area, sometimes in order to further reduce the range of power outages caused by the catenary accident and reduce the voltage loss and power loss of the traction network, it can also be added between the partition office and the traction substation, also known as the auxiliary partition Office (subsectioning post ).
The main device of the switch is circuit breaker. Generally, the power supply line is set to two times. When the power supply line is restored, the uplink and downlink traction networks can lead each time, and the outlets can be set as needed. When the number of outlets is large, you can also segment the bus. If the second power supply is not available in a single line, only one power supply can be introduced.

For the typical structure of the AT traction network auxiliary partition Institute (SSP), see. In the figure, T is the catenary, F is the positive feeder, PW is the protection wire in parallel with the rail, B is the circuit breaker, SD is the security grounding device, and La is the lightning arrester; ot is the control circuit power supply; Pt is the voltage transformer; at is the autocoupling transformer. The protection line is used to form a metal short circuit with the protection line when the catenary or positive feed insulator experiences transient grounding, facilitating power-off protection.

 Partition Kiosk

The partition Pavilion is located in the middle of two traction substations, so that the adjacent catenary Power Supply Section (the upper, downstream or two adjacent substations of the same power supply arm) can be used) achieve parallel or independent work.
If a short-circuit fault occurs in the catenary of a certain section on both sides of the partition Hall, the circuit breaker and the partition pavilion Circuit Breaker of the traction substation of the power supply can automatically trip under the protection of relays, remove the catenary of the fault section, but the catenary of the fault section still works as usual, so that the accident scope is reduced by half.

AtInstitute

When the traction network uses the at power supply mode, an auto-coupling Transformer at is set at about 10km along the railway line. The set premises are called.

 

Composition of the traction network:
1-Wire Feed
2. Catenary
3. Track loop and reflux system

(1) Traction Substation
The traction substation is the heart of the electrified railway. Its function is to deliver the 110kV or 220kV Power Frequency AC high voltage power from the power system, the traction transformer in a certain wiring form is converted into a single-phase power frequency ac of 27.5kV level suitable for Electric Locomotive use, and the electric energy is sent to the electrified railway (catenary) in the corresponding direction through different power feeds, to meet the power supply needs of electric locomotives in different directions. The traction substation is generally located at one end of the station, and is connected to the power supply arm of the other end at the boundary of the station and the other end at different phases through the phase divider or the electrical segment anchor joint. The high-voltage switch of the same direction feedback circuit has a backup switch, which can meet the uninterrupted and reliable power supply requirements and maintenance needs.

(2) Partition Institute

The partitioning system connects the upper and lower lines of the electrified railway through the partitioning system to improve the voltage level of the power supply arm's end contact network, balance the current of the upstream and downstream Power Supply arm, and reduce the power loss; the effect is more obvious when there is a large ramp in the direction and line of heavy vehicles. In the case of a fault in the traction substation, the adjacent traction substation can implement over-the-district power supply through the partitioning.

(3) closed office

The main function of the retreat is to achieve separate and segmented power supply in large marshalling stations and passenger stations, improve the reliability of power supply, reduce the scope of power outages, and reduce the impact of accidents on railway operation. If the shutdown is at the end of the power supply arm, it is usually combined with the partition. Similarly, high-voltage switches with different feed-out circuits have shared bypass backup switches, which can meet the uninterrupted and reliable power supply requirements and maintenance needs.

(4) Feed Wire

The feed wire is the connection line between the traction substation and the catenary. Its function is to supply power to the catenary from the traction substation. It is derived from the feed-out switch and connected to the contact network on both sides of the Electric Phase Separation Device to obtain the 27.5kV power supply.

(5) Catenary

The catenary is the main power supply device on the electrified railway. It passes through the reinforced concrete square column or an equal diameter circle pillar and soft cross, hard crossbar, establish the contact line directly above the railway line in a certain suspension form. Its function is to supply electric energy to electric locomotive (or electric vehicle group) by sliding in contact with the electric bow on the top of the electric locomotive ).

In terms of structure, the catenary consists of the contact suspension part, support device, positioning device, pillar and foundation.
1. Contact Suspension

The contact suspension includes the load cable, the overall suspension string, the contact line, the center anchor, various wire clips, and the full compensation anchor. The load cable bears the gravity of the contact line, transmits the gravity and tension (or pressure) of the entire contact suspension to the support device, and keeps the contact line at the specified height through the suspension of the suspension string, the electric rolling stock receives the electric energy required by the rolling stock from the contact line.

2. Support Device

The supporting devices include wrist arm, rod insulator, fixed base, wrist arm support, diagonal cable, and load cable seat. Used to support contact suspension and transmit its load to the pillar.

2. Positioning Device

The positioning device includes a positioning tube, a positioner, a positioning wire clip, and a positioning support. It is used to fix the horizontal position of the contact line. The positioner is in the pulling status, so that the contact line is evenly distributed along the railway line on both sides of the Locomotive Pantograph center running track, to ensure that the pantograph is not isolated from the contact line and a network-connected accident occurs, and transmit the horizontal load of the contact line to the support device.

4. pillars and foundations

The pillars and foundations include the reinforced concrete pillar, the equal diameter circle pillar, and the steel column, soft spanning, hard crossbar, cup-shaped Foundation, tension-Line Foundation, horizontal layout and bottom plate. It is used to bear all the loads of the catenary, including gravity of the upper structure, tension (or pressure) in the vertical line direction, and tension in the line direction. The quality of its construction directly affects the long-term stable operation of the catenary.

(6) Rail and suction launching

On the electrified railway, electric locomotive uses the traveling rail as the traction current loop, and most of the current goes directly back to the substation through the connected suction line (insulated cable. Because there is no insulation between the track and the earth, part of the traction current must flow through the earth and return to the transformer from the grounding network buried below the traction substation. At the same time, the rails and suction lines are not directly connected, but are added to the insulation section of the Rail circuit. The two are respectively connected to the transformer's wiring column and Neutral Point, in this way, the traction current loop and the track signal loop form an on-going loop and do not interfere with each other.

(7) reflux line

The reflux line is the connection line between the rail circuit and the traction substation. It serves to directly send the traction current flowing through the suction line to the Traction Transformer in the substation. On the one hand, it reduces power loss, on the other hand, it reduces the electromagnetic harmonic interference on the communication, signal lines and devices along the electrified railway. Normally, the reflux line is erected on the same pole as the catenary line, and connected to the rail through the suction line at a certain section.

 

 

(1) Power Supply Mode

AC electrified railway is a single-phase asymmetric power supply system with the catenary-rail-Earth as the loop. Therefore, the electric field and magnetic field generated by the traction power supply system will generate electromagnetic interference on the communication lines. In order to reduce the electromagnetic interference of electrified railways on communication lines, anti-interference measures must be taken during the transformation of electrified railways.

After years of efforts, China has already provided direct power supply, self-coupling transformer power supply (at power supply), suction transformer power supply (BT power supply), and direct power supply that brings back the streamline.

Direct Supply Mode: no special protection measures are added to the traction network, which is generally used only in mountainous areas with few communication lines. The at and Bt power supply modes are complex, therefore, the direct power supply mode that is brought back to the streamline is adopted in the electrification transformation of Shanghai-Hangzhou, Zhejiang-Jiangxi and Beijing-Shanghai Lines.

The direct power supply mode with the streamline is used to cancel the suction Transformer in the BT Power Supply Mode, retain the reflux line, and use the mutual inductance between the catenary and the reflux line, the backflow in the rails is switched back to the substation by the reflux line as much as possible. This partially offsets the interference of the catenary on adjacent communication lines. The anti-interference effect is inferior to that of the BT power supply mode, it is usually used in the area where the anti-interference requirement on the communication line is not high. This power supply method is simple, so the reliability of the power supply equipment has been improved. Because the suction transformer is canceled and only the reflux line is retained, the traction network impedance is lower than the direct supply method, power supply performance is better, and the cost is not high, so this power supply method has been widely used in China's electrified railway.

 

 

Auto-coupling transformer power supply mode (at Power Supply Mode)
Due to the function of the auto-coupling transformer, the current of the catenary and feeder are both I/2, which is in the opposite direction, effectively reducing the interference of the traction network on the communication line.
Because the neutral point of the Self-coupling transformer is connected to the rail, the power supply voltage of the traction network is 2x25 kV, and the voltage is doubled. Therefore, the distance between the traction substations is doubled theoretically. For example, if the distance between the direct supply and reflux lines is 20-30 km, the AT power supply mode is 40-60 km. The AT power supply mode is used for traction power supply systems with heavy loads and high speed and high current.
The feeder current is only half of the direct supply mode.
Traction Network Impedance-AT: 0.09 Ω/km; BT: 0.85 Ω/km; direct supply: 0.33 Ω/km; direct supply + reflux: 0.31 Ω/km

 

 

(2) wiring form of Traction Transformer

Power traction is a primary load, and the traction substation should be powered by two power supplies. When any one road fails, the other road should be powered normally. The traction substation introduces a two-way power supply from the power system. A traction transformer is installed in the traction substation to reduce the high voltage (110kV or 220kV) of the power system to 27.5kV and feed it to the catenary with single-phase electricity, then the catenary is used to supply electric locomotives. The single-phase traction load of the electrified railway is an asymmetric load, which generates negative-Sequence Current and negative-sequence voltage for the three-phase power system. To reduce the impact of negative-sequence current and voltage on the three-phase power system, different types of transformers are usually used to reduce this impact. The Traction Transformer wiring types of electrified railway include single-phase, V, v, three-phase and balanced transformer.

 

 

 

2. Control and Monitoring Devices

3. Relay Protection Device

(1) The main transformer is provided with protection such as differential, gas, overload, overheating, low-voltage startup overcurrent, etc.

(2) distance protection is set up for the substation feeder, and the electric flow rate is disconnected, and an automatic reclosing device is set up.

(3) The 27.5kV parallel Capacitor Compensation Device is protected by speed breaking, overcurrent, differential pressure, and pressure loss.

4. Self-Use Electric System

(1) AC system: the substation is equipped with a two-phase three-phase megav ac bus, which are powered by two self-used transformers connected to the 27.5kV bus and 10 kV line respectively. The two power supplies are mutually hot standby, an automatic input device is provided.

(2) DC system: the smart high-frequency switch DC system is used. The DC operating voltage is 110 V. When the DC power supply is normal, the DC load is provided by the rectifying power supply, and the rectifying power supply is charged and balanced, when the AC is out of pressure, the battery supplies DC load.

(4) Partition one or two devices

Shanghai-Hangzhou, Zhejiang-jiangxi, and Beijing-Shanghai are two-line zones under the Shanghai Railway Bureau. There is a partition center in the middle of the two traction substations. It supplies the uplink and downlink catenary through circuit breakers in parallel. The partition offices in the Shanghai Railway Bureau are designed to be unattended, and the high and low voltage equipment are arranged indoors. The 27.5kV Circuit Breaker adopts the vacuum indoor type, and the relay protection adopts the Integrated Automation System of centralized group-screen microcomputer, the two sections of the feeder are provided with quadrilateral distance protection and overcurrent protection and an automatic reclosing device. The self-use electrical system is the same as the equipment in the traction substation.

(5) shutdown the first and second Devices

There is a switch in the switch, which is a switch station capable of electric segmentation or changing the number of feeder lines. The switch-in-line switch in the Shanghai Railway Bureau introduces a two-way power supply. Normally, one master and one slave are provided, and the two return lines are equipped with a backup power supply self-casting device. In addition to the incoming line isolation switch and lightning arrester, the equipment, the rest are arranged at the indoor grid intervals. The design of the switch is based on unattended design. The 27.5kV Circuit Breaker adopts indoor Vacuum Circuit Breaker and the centralized group-screen microcomputer Integrated Automation System for relay protection, its Incoming Line is configured with over-current protection, the feeder is configured with an electric flow rate cut-off protection, and an automatic rec. The self-use electrical system is the same as the equipment in the traction substation.

(6) catenary Equipment

The catenary is the main power supply device in the traction power supply system of electrified railway. Its function is to continuously supply power to electric locomotives on the railway line. Because the catenary is set in open air, due to the influence of various bad meteorological conditions, the working conditions of the catenary are changed with the operation of the electric locomotive, and there is no backup. Therefore, the working conditions of the catenary are very complex.

In order to meet the requirement of reliable stream Retrieval for the catenary in various situations, the contact suspension of the catenary can be divided into two types: simple suspension chain suspension. Because of the different forms of the contact line and the load-bearing cable anchor, the chain suspension is divided into semi-compensated chain suspension and fully compensated chain suspension. The catenary of the Shanghai Railway Bureau adopts a fully compensated simple chain suspension (see Figure 2-1) with a structure height of 1400mm.

1. Contact Wire, load cable, and additional wire type

Main Line Contact Line using 120mm2 copper alloy wire (CTHA-120), bearing cable using 95mm2 copper alloy wire (THJ-95); Station Line Contact Line using 85mm2 copper alloy wire, bearing cable using 70mm2 copper alloy wire; the additional wire adopts the steel-core aluminum Stranded Wire, wherein the reflux wire adopts the 185mm2 steel-core aluminum Stranded Wire and the air-frame wire adopts the 70mm2 steel-core aluminum Stranded Wire.
2. Suspension type of the catenary Support Device

The catenary is erected along the longitudinal direction of the railway. Different types of structures supporting the contact suspension are supported along different lines. The main structures of the wrist arm are supported in the Section, the support device in the station has a pillar wrist arm, soft cross or hard cross structure, and these structures are in the form of the Shanghai Railway Bureau. The stations on the Beijing-Shanghai, Shanghai-Hangzhou, and Zhejiang-Jiangxi lines mainly adopt a hard cross-structure. Some stations, such as the marshalling stations with many stock roads, adopt a soft cross structure, an automatic Tension Compensation device is used in the soft cross transverse load cable to reduce the temperature impact.

Hard span consists of two columns and a group of steel beams. The steel beams and all the loads in contact suspension are vertically transmitted to the column. Therefore, the column is relatively soft and spans a small amount, so the column capacity is small, from the installation form, the column height requirement is relatively low, and the contact suspension on the hard span has little mutual interference. The adjustment is convenient and the stability is good, which is conducive to high-speed driving. The disadvantage of hard span is that the construction requirements are strict and difficult, and the cost is higher than that of soft span.

Choose the limit positioner for the Main Line positioner on the Beijing-Shanghai, Shanghai-Hangzhou, and Zhejiang-Jiangxi lines to restrict the height of the wire at the positioning point to avoid the occurrence of a network failure. All the hanging strings of the catenary use the overall lifting string, reducing the maintenance workload after operation. The layout of the catenary at the turnout is cross-line. The height of the catenary is designed to meet the requirements for double-layer containers. The requirements for large-scale road maintenance machinery should be considered for the pillar side restriction.

3. pillars and Basic Types

The pillar is used to bear the load of the contact suspension. According to the material, the pillar has a steel column and a prestressed concrete column, and the form has a horizontal abdominal bar, an Equal Diameter Circular Bar Concrete Pillar, an equal diameter round steel column, angle steel truss. In Shanghai-Hangzhou, Zhejiang-jiangxi, and Beijing-Shanghai wire, the contact net wrist arm column mainly adopts a transverse abdominal rod type Prestressed Reinforced Concrete Pillar, and uses a diameter of 400mm in the Shanghai-Nanjing line and other minority ranges (can be stressed in all directions, but a little more steel bars are used ). In some special sections, the circle rod steel pillar is used, and the station soft cross steel pillar is used angle steel truss pillar.

In addition to using cup-shaped Foundation in some soft soil areas, the pillar foundation mainly uses direct burial.

4. Support devices on large construction houses

When a large building, such as a bridge, uses the catenary to install suspension components or pillars for suspension or support. In the Shanghai-Hangzhou line project, there are no available buildings on the Qianjiang second bridge. Therefore, a hard crossbar with non-equal diameter is used to meet the requirements of the catenary suspension. For large passenger stations, such as Shanghai, Zhenjiang, Wuxi, and Suzhou, the catenary structure suitable for the surrounding environment is designed according to the actual situation, which not only meets the requirements for installation of the catenary, it is also very harmonious with the surrounding environment.

5. catenary insulation and power supply segmented form

The insulation of the electrified railway catenary is achieved through insulators, split-phase and segmented insulation devices. Insulator is an important part of the contact suspension to maintain electrical insulation for the pillar or other grounding bodies. The performance of the insulator has a great impact on the normal operation of the catenary, because it is subject to the working voltage and various voltages, along with the weight of the contact suspension and supporting device and the mechanical force such as ice and snow, wind pressure, and vibration, there are strict requirements on the Mechanical and Electrical Performances of insulators.

In order to improve the reliability and flexibility of the catenary power supply, it is required to set up a separate and independent segmented device on the contact network. The electric segmentation of the catenary is generally divided into two types: vertical and horizontal. Vertical electric segmentation refers to the segmentation of the catenary along the line; horizontal segmentation refers to the upper and lower lines of the Two-line section, or between independent parking lots of the station, and segments between stock channels. The power supply segments of the catenary are configured with different structures in different locations based on their functional needs, as shown in Figure 2-10. The power supply segmentation equipment mainly includes the insulation anchor joint, the segmentation insulation device and the phase separation insulation device.