CN110794331B - A rail transit traction transformer inter-turn short circuit detection and protection device - Google Patents
A rail transit traction transformer inter-turn short circuit detection and protection device Download PDFInfo
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- CN110794331B CN110794331B CN201911098406.7A CN201911098406A CN110794331B CN 110794331 B CN110794331 B CN 110794331B CN 201911098406 A CN201911098406 A CN 201911098406A CN 110794331 B CN110794331 B CN 110794331B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/02—Measuring effective values, i.e. root-mean-square values
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
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Abstract
本发明公开了一种轨道交通牵引变压器匝间短路检测及保护装置，变压器各一次侧绕组靠近地端的交汇处延长至变压器外，并分别通过开关继电器串联到电流传感器，电流传感器的输出端连接到低通滤波电路的输入端，低通滤波电路的输出端连接到单片机的输入端；单片机通过积分求解得出各个绕组电流的有效值，并通过比较有效值的大小，来判断各绕组是否发生匝间短路或绕组与变压器外壳短路；当某个绕组电流过大时，单片机向放大电路输出信号，信号经放大电路放大后发送给继电器驱动电路，继电器驱动电路驱动开关继电器切断对应绕组。本发明提高了高铁供电的可靠性以及防止设备损坏等功能，对于检测和预防变压器匝间短路有很高的使用价值。
The invention discloses an inter-turn short-circuit detection and protection device for a rail transit traction transformer. The intersection of each primary side winding of the transformer close to the ground end is extended to the outside of the transformer, and is connected to a current sensor in series through switch relays respectively, and the output end of the current sensor is connected to The input terminal of the low-pass filter circuit and the output terminal of the low-pass filter circuit are connected to the input terminal of the single-chip microcomputer; the single-chip microcomputer obtains the effective value of each winding current through integration, and judges whether each winding has a turn by comparing the size of the effective value. When the current of a certain winding is too large, the single-chip microcomputer outputs a signal to the amplifier circuit, and the signal is amplified by the amplifier circuit and sent to the relay drive circuit, which drives the switch relay to cut off the corresponding winding. The invention improves the reliability of high-speed rail power supply, prevents equipment damage and other functions, and has high use value for detecting and preventing inter-turn short circuits of transformers.
Description
Technical Field
The invention relates to the technical field of rail transit electric energy transmission, in particular to a rail transit traction transformer turn-to-turn short circuit detection and protection device.
Background
The high-speed railway has become a popular main transportation mode in all countries in the world due to the characteristics of rapidness, environmental protection, comfort, safety and the like. In the last decade, with the rapid development of the high-speed rail technology in China, the comprehensive electrification of domestic rail transit lines is basically realized. The running speed of the high-speed rail is continuously improved, the running frequency is stably improved, and stable and continuous electric energy supply and transmission are the basis for safe and reliable running of the train; and the traction transformer is used as the core of the electric energy transmission of the high-speed rail pantograph system, and whether the transformer can work stably and efficiently determines whether the motor car can run safely and normally. When the primary side winding of the transformer is subjected to turn-to-turn short circuit, the current of a fault winding at the primary side of the transformer is increased, so that the heating is increased, and if the fault winding is not processed in time, the transformer can be damaged; in addition, if a certain winding and the transformer shell are short-circuited, large current can be generated, and the transformer shell can be burnt in severe cases.
A transformer is a device for alternating voltage conversion and electric energy transmission by using the principle of electromagnetic induction. Because the high-speed rail traction power transmission line is longer, the line loss is larger when the transmission voltage grade of the long line is lower from the perspective of the electric energy transmission loss of the power system; meanwhile, from the perspective of safety of the electric traction locomotive, if the voltage level is too high, the requirement on the insulation level of the train is higher, so that the voltage level of the high-speed rail contact network in China is generally 27.5 KV. When the high-speed rail pantograph net current collection system transmits electric energy to an electric traction locomotive from a contact net, the electric traction locomotive can be powered only after the voltage of the transformer is reduced, so that whether the transformer can normally work plays an important role in the reliability and safety of the high-speed rail.
Different from the traditional transformer, the vehicle-mounted traction transformer has four windings with the same number of turns on the primary side of the transformer which are connected in parallel and wound on the same iron core in order to improve the reliability of power supply, and the magnetic flux generated by the windings with the same number of turns, namely the main magnetic flux (phi)m=φ1=φ2=φ3=φ4) Are commonly coupled to the secondary side as the secondary sideThe windings provide electric energy, when a certain primary side winding generates turn-to-turn short circuit, the current of the corresponding winding can be increased, and the other three windings can still provide required electric energy for the secondary side of the transformer, so that the normal operation of the motor car equipment is ensured, but if the winding with the turn-to-turn short circuit is not cut off, serious faults such as local temperature surge of the transformer and even transformer burnout can be caused.
When the turn-to-turn short circuit occurs in the conventional vehicle-mounted transformer, the differential protection of the transformer acts to cut off the transformer, so that the power cannot be continuously supplied to the train, a part of power is lost instantly for the train, and the safety and the stability of the train are influenced.
There are two main types of protection against turn-to-turn short in the prior art: differential protection and gas protection. The gas protection is the main protection of the internal faults of the transformer, can reflect all faults in the oil tank, but is easy to act under the interference of some external factors, and is easy to malfunction particularly under the condition that a high-speed rail motor car turns or shakes; the differential protection is also the main protection of the transformer, but because the primary side winding of the vehicle-mounted traction transformer is specially designed, when a certain winding fails, the other three windings can still drive the load to work normally, and the differential protection cannot cut off the failed winding independently, but cut off the transformer from the power supply system, so that the train cannot continue to operate, and the specially designed primary side winding of the vehicle-mounted traction transformer loses the special advantages.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a detection and protection device for inter-turn short circuit of a track traffic traction transformer, which can solve the problems of power loss and equipment burnout of a high-speed rail due to inter-turn short circuit of the transformer or short circuit between a winding and a transformer case, has high power supply reliability, and can effectively detect the inter-turn short circuit of a vehicle-mounted transformer. The technical scheme is as follows:
a track traffic traction transformer turn-to-turn short circuit detection and protection device is characterized in that the junctions of primary windings of a transformer close to the ground end are extended out of the transformer and are respectively connected in series to a current sensor through a switch relay, the output end of the current sensor is connected to the input end of a low-pass filter circuit, the output end of the low-pass filter circuit is connected to the input end of a single chip microcomputer, and the currents of the windings after being filtered are connected to the single chip microcomputer; the single chip microcomputer obtains an effective value of current of each winding through integral solution, and judges whether turn-to-turn short circuit occurs to each winding or the winding and the transformer shell are in short circuit or not through comparison of the effective values; when the current of a certain winding is overlarge, the single chip microcomputer outputs a signal to the amplifying circuit, the signal is amplified by the amplifying circuit and then is sent to the relay driving circuit, and the relay driving circuit drives the switch relay to cut off the corresponding winding.
Furthermore, the output end of the low-pass filter circuit is connected with a voltage follower for isolation.
Furthermore, a voltage stabilizing diode is connected in parallel between the output end of the current sensor and the input end of the singlechip.
Furthermore, the core of the amplifying circuit is an amplifier chip LM324, a positive phase input end of the amplifier chip LM324 is connected to the output end of the single chip microcomputer, a negative phase input end is grounded through a resistor R2, and is connected to the output end of the amplifier chip LM324 through a resistor R1.
Further, the current sensor is a hall element current sensor.
Furthermore, the switch relay is a vacuum high-voltage circuit breaker.
The invention has the beneficial effects that:
1) the differential protection is matched with the specially designed primary side winding of the vehicle-mounted traction transformer, so that the reliability of high-speed rail power supply is ensured, and the power supply efficiency is greatly improved;
2) the invention selects a singlechip to monitor the current of the four branch windings in real time, and is matched with an intelligent program, and when the current change is larger, the corresponding winding is directly cut off; when the current change is not too large, a corresponding warning signal is sent to the cab, and a worker corresponding to the high-speed rail judges whether to select to cut off the winding under the condition;
3) the protection equipment is arranged close to the grounding end, so that the adverse effect and interference of high voltage on the equipment are prevented, and the effect of backflow on weak-current electronic equipment is reduced;
4) the vehicle-mounted traction transformer matched with the specially designed winding can achieve good complementary effect, improves the reliability of high-speed rail power supply, prevents equipment from being damaged and the like, has remarkable progress compared with the prior art, and has high use value for detecting and preventing turn-to-turn short circuit of the transformer.
Drawings
Fig. 1 is a circuit equivalent diagram of the detection and protection device for the turn-to-turn short circuit of the rail transit traction transformer.
Fig. 2 is a diagram of a simple transformer model.
Fig. 3 is a filter circuit diagram.
Fig. 4 is an amplifying circuit diagram of the LM324 chip.
In the figure: 1. 2, 3, 4-primary winding of transformer; 5. 6, 7, 8-current sensors; 9-a low-pass filter circuit; 10-a singlechip central processing unit; 11-an amplifying circuit; 12-a relay drive circuit; 13. 14, 15, 16-switching relays; 17-transformer core; 18-a transformer secondary winding; 19-a voltage follower; 20-a zener diode; 21-transformer housing; 22-filter resistance; 23-a filter capacitance; 24-resistance R1; 25-resistance R2; 26-common grounding (connecting to the vehicle body) of the weak current equipment; 27-primary side working ground (rail); 28-a weak current electronic equipment power supply; and 29-a primary side power supply (contact network) of the transformer.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments. As shown in fig. 1, in the turn-to-turn short circuit detection and protection device for a rail transit traction transformer of the present invention, the junctions of the primary windings 1, 2, 3, 4 of the transformer near the ground end are extended to the outside of the transformer, and are respectively connected in series to the current sensors 5, 6, 7, 8 through the switch relays 13, 14, 15, 16, as shown in fig. 2; the output ends of the current sensors 5, 6, 7 and 8 are connected to the input end of a low-pass filter circuit 9, the output end of the low-pass filter circuit 9 is connected to the input end of a single chip microcomputer 10, and the filtered current of each winding is connected to the single chip microcomputer 10; the single chip microcomputer 10 obtains effective values of currents of all windings through integral solution, and judges whether turn-to-turn short circuit occurs to all the windings or whether the windings are in short circuit with a transformer shell 21 or not through comparison of the effective values; when the current of a certain winding is overlarge, the single chip microcomputer 10 outputs a signal to the amplifying circuit 11, the signal is amplified by the amplifying circuit 11 and then is sent to the relay driving circuit 12, and the relay driving circuit 12 drives the switching relays 13, 14, 15 and 16 to cut off the corresponding winding.
When a winding of the transformer is subjected to turn-to-turn short circuit, the magnetic flux generated by the other three windings is increased, so that the main magnetic flux (phi) is increasedm) The magnetic flux of the fault winding is basically the same as the main magnetic flux generated before the fault, the magnetic flux of the fault winding is basically unchanged, the effective turn number of the fault winding is reduced, and therefore the magnetic induction intensity generated by the fault winding is increased. In order to solve the problems, four relays and four current sensors are arranged on four parallel winding branches, so that whether the winding has a turn-to-turn short circuit fault can be found, the implementation check of the primary detection winding working state of the transformer is realized, and the protection device acts when the winding has a serious turn-to-turn short circuit.
The working mode of the detection device of the invention is as follows: the junction of the primary windings 1-4 close to the ground end is extended to the outside of the transformer, the switch relays 13-16 are connected in series to each primary winding 1-4 close to the ground end, and the current sensors 5-8 are installed at proper positions, so that in order to prevent protection misoperation caused by damage of detection equipment, each winding can be provided with a plurality of current sensors 5-8, and the action accuracy is improved.
The current sensors 5-8 can be selected from Hall element current sensors, the Hall element sensors detect the magnitude of current by using a magnetic field generated by the current, and as the transformer is an element for transmitting energy by using the magnetic field, a shielding device must be added to the current sensors to shield the influence of leakage flux of the transformer. When a turn-to-turn short circuit, a lifting bow and a closed high-voltage vacuum circuit breaker occur, the current may be relatively large, and therefore, the range of the current sensor 5-8 should be left with a proper margin.
The filter circuit is a low pass filter circuit 9 which, although it provides a means of shielding the current sensors 5-8 from interference, will interfere with the sensors or data transmission lines because it is located around the transformer. Since the interference is mostly high frequency waves, the frequency of which is much higher than the frequency of the waveform of the signal to be measured, a suitable low pass filter circuit 9 should be used to obtain a better signal and prevent the influence of the high frequency waves. Meanwhile, in order to prevent the influence of the single chip microcomputer 10 on the filtering signal, a voltage follower 19 needs to be added after the output end of the low-pass filtering circuit 9 for isolation, as shown in fig. 3. Meanwhile, when the pantograph is raised and lowered and the VCB is closed, the current sensor 5-8 can output a high voltage, if a high voltage signal is directly input into the singlechip 10, a chip can be burnt out, and therefore, a voltage stabilizing diode 20 needs to be connected in parallel between the output end of the current sensor 5-8 and the input end of the singlechip 10.
The program in the single chip microcomputer 10 processes the current signals of the four windings 1 to 4 received from the filter circuit 9, and if the current phases of the four windings 1 to 4 may have slight deviation or the phase deviation is too large when turn-to-turn short circuit occurs, not only the real-time signals are meaningless, but also the resources of the processor are occupied. In order to solve the problem, the effective values of the currents of the windings can be solved through integration, the effective values are compared, whether turn-to-turn short circuit occurs to the four windings 1-4 or whether the windings are short-circuited with the transformer shell 21 is judged, and when the current of one winding is too large, and the currents of the other three windings are relatively small and are basically equal in size, the single chip microcomputer 10 sends out a warning signal and a cutting instruction.
When the singlechip 10 sends a cutting-off instruction, the switch relays 13-16 are required to be switched off so as to cut off the fault winding. However, the output signal voltage of the single chip microcomputer 10 is too low to drive the switching relays 13-16, and the output signal needs to pass through the amplifying circuit 11 and then be added to the driving circuit 12 of the relay. Considering that if the amplifying circuit is built by itself, the amplified signal has the problem of noise and the like, in order to improve the reliability, the amplifier chip LM324 is directly selected as the core of the amplifying circuit 11. As shown in fig. 4, the positive phase input terminal of the amplifier chip LM324 is connected to the output terminal of the single chip microcomputer 10, and the negative phase input terminal is grounded through a resistor R2 and connected to the output terminal of the amplifier chip LM324 through a resistor R1.
When a large current is detected, because the circuit breakers 13-16 are in a high-voltage circuit, if the common switch circuit breakers 13-16 are adopted and the switch circuit breakers 13-16 are directly cut off, an arc discharge phenomenon can be generated, and other windings can be burnt out, so that a vacuum high-voltage circuit breaker capable of extinguishing the arc can be selected.
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| CN111460736B (en) * | 2020-04-08 | 2023-11-21 | 天津凯发电气股份有限公司 | Modeling method of traction transformer movable mould test system |
| CN111596225A (en) * | 2020-06-30 | 2020-08-28 | 中车青岛四方机车车辆股份有限公司 | Power supply equipment and detection method for short-circuit fault of traction transformer |
| CN113608147B (en) * | 2021-08-18 | 2024-06-11 | 安徽兆晟新能源科技有限公司 | Transformer short circuit resistance detection device |
| CN114740405A (en) * | 2022-03-10 | 2022-07-12 | 华能铜川照金煤电有限公司 | A system and method for monitoring inter-turn short circuit of motor rotor windings |
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| CN102435903B (en) * | 2011-11-14 | 2013-11-13 | 国网电力科学研究院 | Online monitoring device for turn-to-turn short circuit of voltage transformer |
| CN102570390A (en) * | 2012-03-07 | 2012-07-11 | 华北电网有限公司唐山供电公司 | On-line monitoring and protecting device for series reactor |
| CN106291084B (en) * | 2012-03-15 | 2019-03-15 | 江苏省电力公司常州供电公司 | A method for monitoring short circuit in the near area of a power transformer |
| CN104237727B (en) * | 2014-09-09 | 2017-01-11 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Transformer near-region short circuit signal monitoring device and short circuit recording analysis method |
| US9726706B1 (en) * | 2016-02-10 | 2017-08-08 | General Electric Company | Systems and methods for detecting turn-to-turn faults in windings |
| CN208588789U (en) * | 2018-08-06 | 2019-03-08 | 三峡大学 | On-line monitoring system for inter-turn short-circuit faults of distribution network transformers |
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