The railroad power supply system is divided into 2 parts: ① To provide railroad running? Provide? power traction power supply system; ② undertake traction power supply other than all the railroad load power supply task (this paper referred to as the railroad power supply system), including the signal system, production, station, water supply system and life and other railroad power loads, the reliability of its power supply not only has a direct impact on the normal and safe operation of the railroad transportation system, but also relates to the normal work of many railroad function departments. This paper combines the implementation and application of the distribution scheduling automation system of the Jiayuguan Water and Power Section of the Lanzhou Railway Bureau, discusses the functional requirements of the railroad power supply system for distribution automation, and proposes practical application solutions.
1 Characteristics of the railroad power supply system?
Railway power supply system due to the application of the specificity of the system composition and functionality are different from the characteristics of the power system, mainly reflected in three aspects:?
(1) low voltage level, variable (distribution) power structure is single. From the perspective of the power system, the railroad load belongs to the terminal load, directly facing the end user, so the vast majority of the railroad power supply system for the 10?kV distribution and 35?kV substation, which depends on the local power supply system power supply and the requirements of the railroad in situ load, only in very few places, the existence of a 110?kV substation, but the number of very few.
Because of the functional requirements, the scope of application is basically the same, so the railroad power supply system in the variable (distribution) power house composition is basically the same, the configuration of the function is not much change. According to the railroad substation (distribution) structure and function standardization characteristics, in the railroad power supply system distribution network automation design, the function of the substation (distribution) as a standard implementation of unified consideration.
(2) The system wiring form is simple. Railroad power supply system wiring is like the railroad, is a single radiation network along the railroad laying, each variable (distribution) along the line of the basic uniform distribution, and connected to each other, constituting a hand in hand power supply mode. Connection line has two kinds: one is self-closing line, there is a through the line, the actual system, may be two kinds of connection line have, may be only one of the two. In addition to the realization of the electrical connection between the neighboring offices, but also for the railroad power supply the most important load (automatic blocking signals) to provide power, and its wiring form shown in Figure 1.
Figure 1 railroad power supply system diagram?
(3) high reliability requirements for power supply. Railroad power supply system, although the voltage level is low, the wiring is simple, but the power supply reliability requirements are very high, from the theory, its load (automatic blocking signal) power supply interruption time can not be more than 150?ms, otherwise, it will lead to all the power supply intervals of the automatic blocking signal light into the red, affecting the normal transportation of the railroad.
Because of the importance of the power supply mentioned above, before the application of power distribution automation technology, the railroad power supply system has taken a variety of methods to ensure the reliability of power supply.
The reliability of power supply is ensured by adopting dual power supply and installing automatic input devices for backup power supply. The connection line between neighboring power distribution centers realizes the two connection methods of self-closing line and through line as far as possible, and improves the reliability of connection from the point of view of primary equipment. In the neighboring power distribution through the line protection device and self-closed line protection device to increase the loss of voltage self-injection protection function, in the connecting line because the main power supply can not supply power loss, automatically put into the adjacent standby line switch, quickly restore power supply.
Although the railroad power supply system has taken a number of measures to ensure the reliability of power supply, but because of these measures are limited to the scope of the distribution, so for its most important through the line or the closed line there is no permanent failure of any isolation, localization and restoration measures, which will inevitably lead to the through the line or the closed line of the loss of power, affecting the reliability of the system. At the same time, the characteristics of the railroad power supply system decided that it is far away from the city, overhaul time-consuming and laborious, no accurate fault location also brings great difficulties to the overhaul work. Distribution automation technology brings a fundamental solution to the above problems.
2 The realization of distribution automation?
2.1 Distributed control?
Distributed control mode means that the distribution automation terminal (FTU) has the ability of automatic fault judgment and isolation, and also has the ability of network reconfiguration through the cooperation between each other, and the whole process does not require the participation of the master station. There are mainly voltage time type and current counting type, both by FTU combined with the switch constitutes a sectionalizer with reclosing function.
Due to the limitations of the principle, this approach inevitably has the following defects:?
(1) Fault handling and power supply recovery is slow, and the impact on the system and users is large.
(1) Slow fault processing and power supply recovery, the impact on the system and users.
(2) The need to change the substation outgoing line protection value and reclosing action mode.
(3) The more segments there are, the more difficult it is to cooperate with each other, and the action lacks selectivity.
Therefore, in the railroad power supply system, the power supply mode that requires high reliability of power supply should not be selected.
2.2 Centralized control mode?
Under the centralized control mode, the on-site FTU sends the collected fault information to the master station, and the application module of the master station calculates the fault isolation and recovery plan, and then sends it to the FTU for execution. It is generally divided into three levels: ① the distribution terminal layer completes the detection of faults and the uploading of information; ② the distribution station completes the fault processing and control in the region; ③ the master station completes the management and optimization of the whole network.
This method requires high reliability and rate of communication system, because it needs to transmit fault information and control instructions at high speed during its fault processing. Centralized control mode is built and implemented with a powerful master system as the center, and dedicated advanced application modules can handle responding to complex network structures and fault situations (such as multiple faults). The railroad power supply system is operated on the basis of utility sections, so the distribution automation system should also be established and implemented on the basis of utility sections. Due to the railroad power supply system structure is fixed, the mode is unified, the operation and management is completely completed by the water and electricity section of the dispatching office, so from the completion of the function and saving investment considerations, you can establish a simplified centralized control distribution automation system, in the simplified system, omit the distribution of the electronic station function, by the main station to directly complete the whole network of the distribution of automation application functions.
3 Design and Composition of Distribution Scheduling Automation System of Jiayuguan Hydropower Section
As a pilot project of Lanzhou Railway Bureau, the distribution scheduling automation system of Jiayuguan Hydropower Section is completed, consisting of Jiayuguan Scheduling and Distribution Main Station, Qingshui and Jiuquan two 35kV transformer substations, and two intelligent integrated load switches of Hongshanbao and Shangheqing.?
3.1 System design and composition?
Dispatch distribution master hardware system consists of a server / dispatcher workstations, pre-machines, communication cabinets, taking into account the size of the initial system, the server and dispatcher workstations *** with a machine, but set up as a dual-machine redundancy system, the two machines run in hot standby mode. The software is CSDA2000 distribution automation system, which is an open and expandable cross-operating system platform, integrating all the functions of traditional SCADA system, meanwhile, SCADA/DMS/GIS is designed in a unified way, adopting a unified data model and real-time database platform, which really realizes the integration and carries out the idea of layering of system structure and function. The FA function of distribution automation is completed by the Distribution Network Advanced Application Software (PAS) module in CSDA2000 system, and PAS consists of a number of modularized application software, which completes the three major functions of network operation and control, safety analysis and economic analysis respectively. According to the characteristics of the railroad power supply system, the functions of the PAS are appropriately simplified in this project, and the network topology, fault analysis, fault detection, isolation and recovery and other functional modules are actually applied.
The Shimizu substation was transformed into a comprehensive automation in this project, and a centralized RTU was installed in the Jiuquan substation. According to the functional requirements of the whole system for power distribution, the base unit of the RTU consists of the distribution measurement and control terminal CSF102, while all the protection information is uploaded to the master station through the telecontrol system.?
The intelligent integrated switch consists of the switch body and intelligent controller CSF100. The intelligent controller, as the core, mainly realizes the functions of traditional "three-remote", fault information collection and processing of distribution network, communication, and on-line monitoring of the switch, etc. As the basic equipment of the power distribution automation system, the RTU is composed of the distribution measurement and control terminal CSF102. As the basic equipment of the distribution automation system, the intelligent integrated switch can quickly and accurately monitor fault information and report to the master station, and accept the master station's commands to execute the switch division and closure operations to isolate the fault and restore power supply.
3.2 Communication system design?
The railroad power supply system itself does not have any communication facilities, you must use the railroad system's public **** communication system to transmit data, because this communication network serves the departments used in the railroad, so by the site environment constraints are relatively large, and sometimes may be the communication conditions can not be achieved to achieve a more ideal situation, then it is necessary to take flexible measures.
In this project, the intelligent one switch data must be sent up to the main station through the Jiuquan substation, due to other equipment, the main station and the Jiuquan substation distribution communication protocol can only be used in the Ministry of CDT statute. In order to solve the problem of data ****similar transmission and statute conversion, a powerful communication processor CSE200 was set up in the Jiuquan substation, which realizes upstream data summarization, downstream data diversion, and bi-directional conversion from IEC870-5-101 to CDT statute.
This is only part of the communication problems encountered in the railroad local power supply system, due to the railroad power supply system automation technology lags far behind the electric power system, so the communication system on the power supply system automation part of the construction is not perfect, in order to ensure that the distribution automation system function is perfect under the premise of the distribution automation system applied to the railroad power supply system needs to have a perfect communication system design and flexible configuration In order to better meet the application of railroad power supply system.3.3 Fault test?
In order to verify the function of the entire distribution automation system, the project carried out a complete fault test, the test program shown in Figure 2. The test results show that: when the system fails, the through line protection fast break action, reclosing failure, protection information reported to the master station, start fault processing module (SRS), the master station immediately summoned the FTU fault information, according to the fault information to determine the fault occurs between the F2 and F3, and immediately carry out fault processing, jumping F2, F3, close C1, C4, and accurately complete the fault processing. The whole process was completed within 3?min, which is significant compared with the restoration of power supply in the past several hours.
Figure 2 Fault isolation recovery test?
4 Conclusion?
Railway power supply system can be regarded as a simplified form of electric power supply system, in addition to some special protection functions, other requirements are identical, so the power system in the mature, advanced technology can be fully applied in the railroad power supply system. The current level of automation of the railroad power supply system lags far behind the power system, to take the power system's mature experience and technology to speed up the automation of the railroad power supply system transformation, not only can greatly improve the railroad power supply system's own operation and management level, improve labor productivity, but also on the operation of the entire railroad system is very beneficial.
Railway electric power remote terminal interference
[Abstract] The study analyzes the reasons for electromagnetic interference, characteristics and interference on the electric power remote system, from the point of view of the design of the railroad electric power remote monitoring system for anti-interference analysis and research.
The anti-interference design is an important part of the safe operation of the power remote monitoring system, in the process of developing a comprehensive automation system, if you do not give full consideration to the reliability of the problem, in the strong electric field interference, it is easy to error, so that the whole power remote monitoring system can not operate normally or out of the error (false tripping accidents, etc.), can not be supplied to the station and the zone, affecting the safety of railroad traffic.
First, the causes and characteristics of electromagnetic interference
(a) Conducted transient and high-frequency interference
1. Due to lightning strikes, circuit breaker operations and short-circuit faults caused by surge and high-frequency transient voltages or currents through the transformer (distribution) of the secondary side of the power station to enter the telematics terminal equipment, interference with the normal operation of the equipment, and severe damage to the circuit. 2. Transient interference caused by electromagnetic relay, high voltage amplitude, short time, high repetition rate, equivalent to a series of pulse groups. 3. Railway power supply, especially the modern high-speed railroads on the power requirements are relatively high, generally several power supply, bus switching conversion is more frequent, the number of times the oscillation wave occurs more often.
(B) the field of interference
1. Under normal circumstances, the steady-state magnetic field and short-circuit accident transient magnetic field of two kinds, especially short-circuit accidents on the magnetic field of the monitor and other impact is relatively large. 2. Due to the operation of the circuit breaker or short-circuit accidents, lightning strikes and other impulses caused by the magnetic field. 3. Substation isolation switches and high-voltage cabinets handcart in the operation of the transient process of damping oscillation, but also generate a certain amount of magnetic field. 4. Generate a certain magnetic field. 4. wireless communications, walkie-talkies and other radiated electromagnetic fields on the remote terminal will produce a certain amount of interference, the railroad relay station will usually be and communication station in one place, communication towers on the relay station power remote terminal equipment interference is relatively large.
(C) on the communication line interference
1. Railway substation remote terminal data by the serial communication through the twisted pair into the station communication station, and then converted into optical signals along the special communication fiber optic cable of the Railway Communication sent to the power remote scheduling center, telecommunication and remote control data in the substation to the communication station in the course of the walk is a telecommunication signal, due to substation high and low-voltage in and out of the cable is a lot of remote terminals are subject to greater interference. 2. The relay station is generally closer to the railroad, the vibration of the train through the remote terminal equipment has a certain interference.
(4) Relay itself
Relay itself may be due to some reason a one-time not close in place and produce interference vibration signal, or load switch, circuit breaker, disconnecting switch and other secondary side of the vibration signal.
Second, the impact of interference on the power telematics system
Whether AC power supply or DC power supply, power supply and interference between the coupling channel are relatively more, it is easy to affect the telematics terminal equipment, including the vital CPU; analog input interference may cause sampling data errors, affecting the accuracy of the precision and metering accuracy, but also may cause the microcomputer protection misbehavior, Damage to remote terminal equipment and microcomputer protection part of the components; switching input and output channels are disturbed, may lead to microcomputer and remote terminal judgment error, remote debugging terminal data error remote terminal CPU interference will lead to CPU work is not normal, can not work properly, may also lead to the remote terminal program is damaged.
Third, anti-interference design analysis
(a) shielding measures
1. High-voltage equipment and remote terminal input, output using armored (shielding layer) of the cable, cable steel armor grounded at both ends, so that you can reduce the coupling of induced voltages to a large extent. 2. In the selection of substation and relay station power equipment as far as possible to choose the transformer with a special shielding, but also to prevent high-frequency interference into the remote terminal. Favorable to prevent high-frequency interference into the remote terminal equipment inside. 3 in the remote terminal equipment on the input terminals of a high voltage resistant small capacitors to ground, can effectively inhibit external high-frequency interference.
Two) system grounding design
1. primary system grounding is mainly for lightning protection, neutral grounding, protection equipment, the appropriate grounding system can effectively protect the safe operation of equipment, for the circuit breaker cabinet grounding to increase the number of grounding flat iron and grounding electrode, the grounding of equipment to increase the increase of grounding network interconnection line, reduce the transient potential difference in the grounding network, improve the secondary equipment, and improve the electromagnetic compatibility of the remote terminal equipment. Electromagnetic compatibility of the secondary system grounding is divided into safety grounding and work grounding, safety grounding is mainly to avoid the staff due to equipment insulation damage or insulation reduction, suffered electrocution hazards and to ensure the safety of the equipment, the equipment shell grounding, grounding wire using a multi-stranded copper wire, conductivity, grounding is firm and reliable, safety grounding network can be connected to the grounding network and the primary equipment; Work grounding is to give electronic equipment, microcomputer control systems and protection devices a potential reference to ensure its reliable operation, to prevent ground loop interference. 3. As the high and low voltage cabinets are more than galvanized sheet steel material, itself has a shielding effect, will be high and low cabinet are reliably grounded. 4. Remote terminal microprocessor power supply ground and digital ground is not connected to the enclosure shell, so that you can reduce the power line with the enclosure between the distributed capacitance, improve the resistance to **. Distributed capacitance, improve the ability to resist **** mode interference, can significantly improve the safety and reliability of the power remote monitoring system.
(C) take good isolation measures
1. In order to avoid remote terminal power supply interference to take the isolation transformer, power supply high-frequency noise is mainly through the transformer primary and secondary parasitic capacitance coupling, the isolation transformer primary and secondary by the shielding layer isolation, distribution capacitance is small, and can improve the resistance to ****-mode interference. 2. power remote monitoring system switching volume inputs The main circuit breaker, isolation switch, load switch auxiliary contacts and power regulator tap position, etc., the output of the switching quantity is mainly the control of the circuit breaker, load switch and power regulator tap.3. Signal cables try to avoid power cables as much as possible, and pay attention to avoiding mutual inductance in the printing of the circuit board wiring of the remote terminals.4. Adopt optoelectronic coupling isolation, the input impedance of the optoelectronic coupler is very small and the interference source has large resistance, and the input/output circuits are separated by shielding layer, which can improve the resistance to *** mode interference. The input impedance of the photocoupler is very small, while the internal resistance of the interference source is very large, and the distribution capacitance between the input/output circuits is very small, and the insulation resistance is very large, so it is difficult for the interference on one side of the circuit to be sent to the other side through the photocoupler, which effectively prevents the interference from entering into the main CPU from the process channel.
(D) Design of the filter
1) Low-pass filtering is used to remove the high harmonics.2) Dual symmetrical inputs are used to inhibit the interference of the ****mode. Discrete acquisition mode, and select the corresponding digital filtering technology.
(E) decentralized independent function block power supply, each function block is set up a separate voltage overload protection, will not be due to the failure of a regulated power supply and the destruction of the entire system, but also reduces the mutual coupling of the public **** impedance and the coupling of the public **** power supply, greatly improving the reliability of the power supply.
(F) data acquisition anti-interference design
1. In the information acquisition, the cancellation of the specialized transmitter screen cabinet, the transmitter part of the package in the RTU to reduce the intermediate links, so that you can reduce the transmitter part of the output of the length of the weak current circuits. 2. Remote signal due to the closing of the gate once out of place or due to the vibration of the secondary side of the erroneous remote signal interference signals and will also produce a sharp pulse signal, may also have a negative impact on the remote signal. Sharp pulse signal, may also produce interference to the telecommunication circuit false remote signal.
(G) Process channel anti-interference design
(H) Printed circuit board design. In the printed circuit board design as far as possible to separate the digital circuit ground and analog ground circuit ground; power input across the 10 ~ 100μF electrolytic capacitors.
(ix) control state bit interference design
(x) program malfunction anti-interference design
(xi) microcontroller software anti-interference design
(xii) for the terminal to the communication station of the digital communication cable plus through the steel pipe, especially when crossing other power cables, to avoid laying the same ditch as the other power cables and maintain a certain cross-distance. distance.
(xiii) For special variable (distribution) power station or interval signal station environment
(xiv) Improve the reliability of remote information transmission, in the power dispatch center and remote terminal to establish between the error retransmission technology until the residence to confirm the information.