The railway power supply system is divided into two parts: ① providing railway traffic? Provide? Power supply of traction power supply system; (2) To undertake the power supply tasks of all railway loads except traction power supply (hereinafter referred to as railway power supply system), including railway power loads such as signal system, production, station, water supply system and life. Its power supply reliability not only directly affects the normal and safe operation of the railway transportation system, but also relates to the normal work of many railway functional departments. Based on the implementation and application of the distribution dispatching automation system of Jiayuguan Hydropower Station in lanzhou railway administration, the functional requirements of railway power supply system for distribution automation are discussed, and the practical application scheme is put forward.

1 What are the characteristics of railway power supply system?

Due to the particularity of application, the railway power supply system has some characteristics different from the power system in system composition and function, which are mainly reflected in three aspects:?

(1) The voltage level is low, and the transformer (distribution) substation has a single structure. From the perspective of power system, the railway load belongs to the terminal load and directly faces the end users, so the vast majority of railway power supply systems are 10? KV substation and 35? KV substation, which depends on the power supply situation of local power supply system and the requirements of local railway load, exists only in a few places, including 1 10? KV substations, but few in number.

Because the functional requirements and application scope are basically the same, the composition of transformers (distribution) in railway power supply system is basically the same, and the power supply configuration has not changed much. According to the characteristics of standardization of structure and function of railway substation, the function of substation can be considered as a standard realization method when designing distribution automation of railway power supply system. ?

(2) The wiring form of the system is simple. The wiring of railway power supply system, like the railway, is a single radiation network laid along the railway, and transformers (distribution stations) are basically evenly distributed along the railway and connected with each other to form a hand-in-hand power supply mode. There are two kinds of connecting lines: one is self-closing line and the other is through line. In the actual system, there may be two kinds of connecting wires or only one kind. The connecting line not only realizes the electrical connection between adjacent stations, but also provides power for the most important load (automatic block signal) of railway power supply, and its wiring form is shown in figure 1. ?

Figure 1 Railway Power Supply System Diagram?

(3) High power supply reliability. Although the railway power supply system has low voltage level and simple wiring mode, it requires high reliability of power supply. Theoretically, the power supply interruption time of its load (automatic block signal) cannot exceed 150? Ms, otherwise the automatic blocking signal lights in all power supply sections will turn red, which will affect the normal railway transportation. ?

Because of the importance of the above power supply, before the application of distribution automation technology, the railway power supply system has adopted various methods to ensure the reliability of power supply.

Double power supply is adopted, and automatic switching-in device of standby power supply is installed to ensure the reliability of power supply. As far as possible, the connecting lines between adjacent distribution stations are connected by self-closing lines and through lines, so as to improve the reliability of the connection from the perspective of primary equipment. The through line protection device and self-closing line protection device of adjacent distribution stations have added the function of automatic closing under voltage loss. When the connecting line is cut off because the main power supply station cannot supply power, it will automatically close the line switch of the adjacent standby station to quickly restore power supply. ?

Although many measures have been taken in the railway power supply system to ensure the reliability of power supply, because these measures are limited to the scope of distribution stations, when the most important through-lines or self-closing lines have permanent faults, they are not isolated, located and restored, which will inevitably lead to the power loss of the through-lines or self-closing lines and affect the reliability of the system. At the same time, the characteristics of railway power supply system determine that it is far from the city, and maintenance is time-consuming and laborious, and it is also very difficult to locate the fault accurately. Distribution automation technology fundamentally solves the above problems.

2. How to realize distribution automation?

2. 1 distributed control mode?

Distributed control means that FTU has the ability of automatic fault judgment and isolation, and also has the ability of network reconfiguration through mutual cooperation, and the whole process does not need the participation of the main station. There are mainly voltage time type and current counting type, both of which are segmented devices with coincidence function composed of FTU combined with switches.

Due to the limitation of principle, this method inevitably has the following defects:?

(1) The speed of fault handling and power supply recovery is slow, which has a great impact on the system and users.

(2) It is necessary to change the setting value of substation outlet protection and the action mode of reclosing. ?

(3) The more segments, the more difficult it is to cooperate with each other, and the action lacks selectivity. ?

Therefore, this mode should not be selected in the railway power supply system, which requires high power supply reliability. ?

2.2 Centralized control mode?

In centralized control mode, the field FTU sends the collected fault information to the master station, and the master station application module calculates the fault isolation and recovery scheme, and then sends it to FTU for execution. Generally, it is divided into three levels: ① the distribution terminal layer completes fault detection and information transmission; (2) Using electronic station to complete the fault handling and control in this area; ③ The master station completes the management and optimization of the whole network. ?

This method requires high reliability and speed of communication system, because fault information and control instructions need to be transmitted at high speed during fault handling. The centralized control mode is established and realized around the powerful master station system, and the specialized advanced application module can deal with complex network structure and fault situations (such as multiple faults). Railway power supply system is based on hydropower station, so distribution automation system should also be established and implemented on hydropower station. Because the railway power supply system has a fixed structure and unified mode, and the operation and management are completely completed by the dispatching room of hydropower station, a simplified centralized control distribution automation system can be established from the aspects of perfect function and investment saving. In the simplified system, the function of distribution electronic station is omitted, and the main station directly completes the application function of distribution automation in the whole network. ?

3 Jiayuguan hydropower station distribution dispatching automation system design and composition

As a pilot project in lanzhou railway administration, the distribution dispatching automation system of Jiayuguan Hydropower Station has been built, which consists of Jiayuguan dispatching main station, two 35kV substations in Qingshui and Jiuquan, and two intelligent integrated load switches in Hongshanbao and Shangheqing. ?

3. 1 system design and composition?

The hardware system of dispatching and distribution master station consists of server/dispatcher workstation, front-end computer and communication cabinet. Considering the initial system scale, the server and dispatcher workstation use one machine, but it is set as a dual-machine redundant system, and the two machines operate in hot standby mode. The software is CSDA2000 distribution automation system, which is an open and extensible cross-operating system platform and integrates all the functions of traditional SCADA system. At the same time, SCADA/DMS/GIS is designed in a unified way, with a unified data model and real-time database platform, which truly realizes integration and implements the idea of hierarchical architecture and functions. The FA function of distribution automation is completed by the distribution network advanced application software (PAS) module in CSDA2000 system. PAS is composed of several modular application software, which respectively completes three functions: network operation control, security analysis and economic analysis. According to the characteristics of railway power supply system, the functions of PAS are simplified appropriately in this project, and functional modules such as network topology, fault analysis, fault detection, isolation and recovery are actually applied. ?

In this project, Qingshui Substation has undergone comprehensive automation transformation, and Jiuquan Substation has installed centralized RTU. According to the power distribution function requirements of the whole system, the basic unit of RTU is composed of distribution measurement and control terminal CSF 102, and all protection information is sent to the main station through the telecontrol system. ?

Intelligent integrated switch consists of switch body and intelligent controller CSF 100. With the intelligent controller as the core, it mainly realizes the traditional functions of fault information collection and processing, communication, on-line monitoring of switches and so on. As the basic equipment of distribution automation system, intelligent integrated switch can quickly and accurately monitor the fault information and report it to the main station, accept the command of the main station to perform the opening and closing operation of the switch, isolate the fault and restore power supply. ?

3.2 communication system design?

The railway power supply system itself has no communication facilities, so it needs to use the public communication system of the railway system to transmit data. Because this kind of communication network serves the railway departments and is greatly restricted by the field environment, sometimes the communication conditions may not be ideal, so flexible measures must be taken. ?

In this project, the data of intelligent integrated switch must be sent to the main station through Jiuquan substation. Due to other equipment, the communication protocol between the main station and Jiuquan substation can only adopt ministerial CDT protocol. In order to solve the problem of data transmission and protocol conversion at the same time, Jiuquan Substation has set up a powerful communication processor CSE200, which realizes the collection of uplink data, the diversion of downlink data and the bidirectional conversion from IEC870-5- 10 1 to CDT protocol.

This is only a part of the communication problems encountered by the railway local power supply system. Because the automation technology of railway power supply system lags far behind the power system, the construction of automation part of power supply system in communication system is still not perfect. On the premise of ensuring the perfect function of distribution automation system, the distribution automation system applied to railway power supply needs perfect communication system design and flexible configuration to better meet the application of railway power supply system. ?

3.3 failed test?

In order to verify the function of the whole distribution automation system, this project has carried out a complete fault test, and the test scheme is shown in Figure 2. The test results show that when the system fails, the through-line protection moves quickly and the reclosing fails. The protection information is reported to the master station, and the fault handling module (SRS) is started. The main station immediately calls FTU fault information, judges that the fault occurs between F2 and F3 according to the fault information, and immediately handles the fault, skipping F2 and F3, and combining C 1 and C4 to accurately complete the fault handling. The whole process is in 3? It will be completed in minutes, which is self-evident compared with the restoration of power supply in the past few hours.

Figure 2 Fault isolation recovery test?

4 conclusion?

Railway power supply system can be regarded as a simplified form of power supply system. Except for some special protection functions, other requirements are completely consistent, so the mature and advanced technology in the power system can be applied to the railway power supply system. At present, the automation level of railway power supply system lags far behind that of electric power system. Adopting the mature experience and technology of power system and accelerating the automation transformation of railway power supply system can not only greatly improve the operation and management level of railway power supply system itself, but also improve labor productivity, which is of great benefit to the operation of the whole railway system.

Railway electric power telecontrol terminal interference

【 Abstract 】 The reasons, characteristics and effects of electromagnetic interference on electric power telecontrol system are studied, and the anti-interference analysis and research on railway electric power telecontrol monitoring system are carried out from the design point of view.

Anti-interference design is an important part of the safe operation of power telecontrol monitoring system. In the process of developing integrated automation system, if the reliability problem is not fully considered, it is easy to make mistakes under the interference of strong electric field, which will make the whole electrical telecontrol monitoring system unable to operate normally or make mistakes (false trip accidents, etc.). ), unable to supply power to stations and sections, affecting railway traffic safety.

First, the causes and characteristics of electromagnetic interference

(a) Conducted transients and high-frequency interference

1. Surge and high-frequency transient voltage or current caused by lightning strike, circuit breaker operation and short circuit fault enter the remote terminal equipment through the secondary side of transformer (distribution station), which will interfere with the normal operation of the equipment and seriously damage the circuit. 2. The transient interference voltage caused by electromagnetic relay is high in amplitude, short in time and high in repetition rate, which is equivalent to a series of pulse groups. 3. In the railway power supply, especially the modern high-speed railway, the demand for electricity is relatively high. Generally, it is powered by several power sources, with frequent bus switching and more oscillation waves.

(2) On-site interference

1. There are two kinds of static magnetic field under normal conditions and transient magnetic field during short circuit accident, especially the magnetic field during short circuit accident has great influence on the display. 2. Pulse magnetic field caused by circuit breaker operation or short circuit accident, lightning strike, etc. 3. The transient process of damping oscillation caused by isolating switch and high-voltage cabinet handcart in substation also produces a certain magnetic field. 4. The electromagnetic fields radiated by radio communication and walkie-talkie will cause certain interference to the telecontrol terminal. Railway relay stations are usually located in the same place as communication stations, and communication towers have great interference to the power telecontrol terminal equipment of relay stations.

(3) Interference with communication lines

1. The data of the railway substation telecontrol terminal enters the station communication station through twisted-pair serial communication, and then is converted into optical signals, which are sent to the electric power telecontrol dispatching center along the special communication optical cable of Tietong. In the process from substation to communication station, telecommunication and remote control data are in the form of electrical signals. Because there are many high and low voltage cables entering and leaving the substation, it has great interference to the telecontrol terminal. 2. The relay station is generally close to the railway, and the vibration when the train passes has certain interference to the telecontrol terminal equipment.

(d) the relay itself

The relay itself may not be in place at one time for some reason, resulting in interference vibration signals, or the secondary side such as load switch, circuit breaker and disconnector may produce vibration signals.

Second, the influence of interference on power telecontrol system

Whether AC power supply or DC power supply, there are relatively many coupling channels between power supply and interference sources, which are easy to affect telecontrol terminal equipment, including key CPU；; The interference of analog input may cause errors in sampling data, affect the accuracy of precision and measurement, and may also cause misoperation of microcomputer protection, damaging telecontrol terminal equipment and some components of microcomputer protection; The interference of switch input and output channels may lead to misjudgment of microcomputer and telecontrol terminal, and data error of telecontrol debugging terminal. The interference of remote terminal CPU may lead to the abnormal operation of CPU, and may also lead to the damage of remote terminal program.

Third, anti-interference design analysis

Shielding measures

1. The input and output of high-voltage equipment and telecontrol terminal adopt cables with armor (shielding layer), and both ends of the steel armor of the cable are grounded, which can greatly reduce the coupling induced voltage. 2. When selecting power supply equipment for substations and relay stations, try to choose transformers with special shielding layers, which is also beneficial to prevent high-frequency interference from entering telecontrol terminal equipment. 3. Connecting a small capacitor with high voltage resistance to ground at the input end of the telecontrol terminal equipment can effectively suppress external high-frequency interference.

2) System grounding design

1. Primary system grounding is mainly used for lightning protection, neutral grounding and equipment protection. Proper grounding system can effectively ensure the safe operation of equipment. For the grounding position of circuit breaker cabinet, the number of grounding flat iron and grounding electrode should be increased, and the interconnection lines of grounding network should be increased to reduce the transient potential difference in grounding network, improve the electromagnetic compatibility of secondary equipment and reduce the interference to remote terminals. 2. The grounding of the secondary system is divided into safety grounding and working grounding. Safety grounding is mainly to avoid the risk of electric shock when the insulation of the equipment is damaged or reduced, and to ensure the safety of the equipment. The equipment shell is grounded, and the grounding wire adopts multi-strand copper flexible wire, which has good conductivity and reliable grounding. The safety grounding grid can be connected with the grounding grid of primary equipment; The purpose of working grounding is to provide a potential reference for electronic equipment, microcomputer control system and protection device, so as to ensure their reliable operation and prevent the interference of earth circulation. 3. Because the high and low voltage cabinets themselves are mostly galvanized steel plates, they also have shielding effect, and the high and low voltage cabinets are reliably grounded. 4. The power ground and digital ground of the telecontrol terminal microcomputer are not connected with the shell, which can reduce the distributed capacitance between the power line and the shell, improve the anti-interference ability of * * * mode, and obviously improve the safety and reliability of the electric telecontrol monitoring system.

(3) Take good isolation measures.

1. In order to avoid the power interference of the telecontrol terminal itself, an isolation transformer is adopted. The high-frequency noise of the power supply is mainly coupled by the primary and secondary parasitic capacitances of the transformer, and the primary and secondary of the isolation transformer are isolated by the shielding layer, so the distributed capacitance is small, which can improve the ability of resisting * * * mode interference. 2. The switch input of power telecontrol monitoring system is mainly the position of auxiliary contact of circuit breaker, disconnector, load switch and tap of power regulator. , and the output of the switch is mainly to control the tap of the circuit breaker, load switch and power regulator. 3. The signal cable should avoid the power cable as far as possible, and pay attention to avoid mutual inductance when wiring the telecontrol terminal circuit board. 4. Using photoelectric coupling isolation, the input impedance of photoelectric coupler is very small, but the internal resistance of interference source is very large, and the distributed capacitance between input/output circuits is very small and the insulation resistance is very large, so it is difficult for interference from one side of the circuit to be sent to the other side through optical coupling, which can effectively prevent interference from entering the main CPU from the process channel.

(4) Design of filter

1. Use low-pass filtering to remove higher harmonics. 2. Double-ended symmetrical input is used to suppress the interference of * * mode, and the software adopts discrete acquisition mode and corresponding digital filtering technology.

(5) Power is supplied by independent functional blocks, and each functional block has a separate voltage overload protection, so that the whole system will not be damaged due to the failure of the regulated power supply, and the mutual coupling between the public impedance and the public power supply is also reduced, which greatly improves the reliability of power supply.

(6) Anti-interference design of data acquisition

1. When collecting information, cancel the special transmitter cabinet, encapsulate the transmitter part in RTU, and reduce intermediate links, which can reduce the length of weak current loop output by the transmitter part. 2. Telecommunication is a false telecommunication interference signal caused by primary closing failure or secondary side vibration, which will also produce sharp pulse signals and may also interfere with telecommunication circuits.

(7) Anti-interference design of process channel

(8) Design of printed circuit board. In the design of printed circuit board, digital circuit grounding and analog circuit grounding should be separated as far as possible; The input end of the power supply is connected across the electrolytic capacitor of10 ~100μ f.

(9) Interference design of control status bits

Anti-interference design of (10) abnormal program operation

Anti-interference design of (1 1) single chip microcomputer software

(12) When the digital communication cable from the terminal to the communication station passes through the steel pipe, especially when it crosses other power cables, it should be avoided to be laid in the same trench with other power cables and keep a certain crossing distance.

(thirteen) special substation (distribution station) or interval signal station environment.

(14) Improve the reliability of telecontrol information transmission, and establish error retransmission technology between the power dispatching center and the telecontrol terminal until the confirmation information remains.