CN111289919B - Multi-range contact net leakage current detection device - Google Patents
Multi-range contact net leakage current detection device Download PDFInfo
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- CN111289919B CN111289919B CN202010261096.2A CN202010261096A CN111289919B CN 111289919 B CN111289919 B CN 111289919B CN 202010261096 A CN202010261096 A CN 202010261096A CN 111289919 B CN111289919 B CN 111289919B
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Abstract
The invention discloses a multi-range contact net leakage current detection device, which comprises a C-shaped magnetic core, wherein a power supply cable of a tested contact net penetrates through the center position of the C-shaped magnetic core, a Hall sensor is arranged at an air gap of the C-shaped magnetic core, a compensation coil is wound on the C-shaped magnetic core, a current loop is arranged between the compensation coil and the Hall sensor, and a closed loop driving circuit module and a compensation coil selection module are sequentially arranged on the current loop; the closed-loop driving circuit module is also provided with an analog/digital processing module and a CPU processing module respectively, the analog/digital processing module is connected with the CPU processing module, and the CPU processing module is connected with the output module. The three-range automatic switching can overcome the defects of insufficient range or insufficient measurement precision in most existing schemes, and has wider applicability.
Description
Technical Field
The invention relates to the technical field of rail transit, in particular to a multi-range contact net leakage current detection device.
Background
In a rail transit system, a contact network is a special-form power transmission line which is erected above a subway line and supplies power to a locomotive, and the contact network is an important task of directly transmitting electric energy obtained from traction power transformation to the locomotive for use, so that the quality and the working state of the contact network are extremely important. The contact net structure is complicated, and operational environment is abominable, and constantly vibrates the surrounding environment at the operation in-process of locomotive and easily causes the contact net dirty, and contact net equipment easily takes place insulation breakdown etc. and causes phenomenons such as ground connection short circuit tripping operation.
The fault judgment of the contact network in the rail transit system is realized through the protection devices in the direct current switch cabinets supplied with power from two sides of the contact network, but if the leakage current value does not reach the tripping protection fixed value at the moment, the three-phase current of the alternating current part of the traction power supply system does not change, the voltage capable of contacting the contact network is reduced by a certain amplitude, and the current slightly leaks. When the small current leakage of the contact net exceeds a certain threshold, the insulator, the cable and the like can be burnt out.
If the situation happens, the reason needs to be manually found, and because no relevant leakage current value data is taken as a basis, the inspection can be only carried out on all sections of the whole line of the contact network, so that the normal operation of the subway can not be ensured, a large amount of workload can be brought to subway maintenance personnel, the subway maintenance cost is increased, and even direct current and alternating current traction power supply system equipment can be seriously damaged or even personal safety accidents can be caused in serious cases.
At present, the detection technology for the leakage current generally adopts an open loop mode, and the magnetic flux change caused by the leakage current is measured by using the principle of the hall effect so as to estimate the size of the leakage current. However, the reliability of the measurement result is not ideal, because the current value of the leakage current varies indefinitely, the fluctuation span is large, the sampling element with a single range is easy to have primary current over-range and magnetic core saturation, and further output voltage is full-biased, and the leakage current value cannot be accurately measured, and if the sampling element with a wide range (1A-100A) is selected, the small leakage current cannot be detected in time.
Disclosure of Invention
Aiming at the problems, the invention provides a multi-range contact net leakage current detection device and a multi-range contact net leakage current detection method, which mainly solve the problems in the background technology.
The invention provides a multi-range contact net leakage current detection device, which comprises a C-shaped magnetic core, wherein a power supply cable of a detected contact net penetrates through the center position of the C-shaped magnetic core, a Hall sensor is arranged at an air gap of the C-shaped magnetic core, a compensation coil is wound on the C-shaped magnetic core, a current loop is arranged between the compensation coil and the Hall sensor, and a closed loop driving circuit module and a compensation coil selection module are sequentially arranged on the current loop;
The closed loop driving circuit module is also provided with an analog/digital processing module and a CPU processing module respectively, the analog/digital processing module is connected with the CPU processing module, and the CPU processing module is connected with the output module.
The further improvement is that the number of the compensation coils is at least 3, the compensation coils are respectively a first compensation coil, a second compensation coil and a third compensation coil, the current range of the first compensation coil is 0-10 mA, the current range of the second compensation coil is 10-1A, and the current range of the third compensation coil is 1-100A.
The further improvement is that the compensation coil selection modules are used for connecting/disconnecting a current loop between the compensation coils and the Hall sensor, and the number of the compensation coil selection modules corresponds to the number of the compensation coils one by one.
The further improvement is that the number of the closed-loop driving circuit modules corresponds to the number of the compensation coils one by one, and a plurality of the closed-loop driving circuit modules are connected with the wiring terminals of the Hall sensor in parallel.
The further improvement is that an automatic early warning module is arranged in the closed-loop driving circuit module, and when the circuit passing through the closed-loop driving circuit module exceeds the range, the automatic early warning module transmits alarm information to the CPU processing module.
In a further improvement, the output module at least comprises an Ethernet interface and a fiber interface.
The further improvement is that the Hall sensor is a magnetic balance type current sensor.
The closed-loop driving circuit module comprises a conditioning circuit module, a coil driving module and a sampling amplification module, wherein the input end of the conditioning circuit module is connected with the wiring end of the Hall sensor, the output end of the conditioning circuit module is connected with the input end of the coil driving module, and the output end of the coil driving module is connected with the compensation coil selection module.
The further improvement lies in that a resistor Rs is arranged on a connecting circuit of the coil driving module and the compensation coil selection module, and the sampling amplification module is connected with the resistor Rs in parallel.
In a further refinement, the sampling amplification module is adapted to measure and amplify the differential pressure V at Rs and to pass the differential pressure V information to the analog/digital processing module.
Compared with the prior art, the invention has the beneficial effects that:
the invention adopts a closed-loop control mode, utilizes the compensating coil to provide driving current to counteract magnetic flux change caused by leakage current, and finishes the sampling of the leakage current by measuring the voltage at two ends of the resistor Rs. Considering the amplitude change of the leakage current in reality, aiming at ensuring the measurement precision and accuracy, the invention designs a compensation sampling circuit with three current measurement ranges (0-10 mA, 10 mA-1A and 1A-100A), and switches to a proper measurement channel according to the actual leakage current numerical value to finish the measurement of the leakage current. The acquired measured value is transmitted to a CPU processing module through an analog/digital processing module and is transmitted to an external upper computer or other monitoring platforms in a digital quantity form through an Ethernet port and an optical fiber interface, so that the conversion of leakage current from analog quantity to digital quantity is realized; the invention can not only accurately measure the value of the leakage current, but also ensure the reliability of the measurement result by transmitting in a digital quantity form, provide favorable assistance for the rail maintenance work, improve the working efficiency of subway maintenance personnel and save the cost. The three-range automatic switching can overcome the defects of insufficient range or insufficient measurement precision in most existing schemes, and has wider applicability.
Drawings
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the present embodiments, certain elements of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
FIG. 1 is a schematic overall structure diagram of an embodiment of the present invention;
wherein: 1. a compensation coil selection module; 2. a first compensation coil; 3. a power supply cable; 4. a C-shaped magnetic core; 5. a closed loop drive circuit module; 6. an analog/digital processing module; 7. a CPU processing module; 8. an Ethernet interface; 9. an optical fiber interface; 10. a Hall sensor; 11. a second compensation coil; 12. a third compensation coil; 13. an automatic early warning module; 14. a conditioning circuit module; 15. a coil driving module; 16. and a sampling amplification module.
Detailed Description
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, so to speak, as communicating between the two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art. The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Referring to fig. 1, the multi-range contact network leakage current detection device comprises a C-shaped magnetic core 4, a power supply cable 3 of a detected contact network penetrates through the center position of the C-shaped magnetic core 4, a hall sensor 10 is arranged at an air gap of the C-shaped magnetic core 4, a compensation coil is wound on the C-shaped magnetic core 4, a current loop is arranged between the compensation coil and the hall sensor 10, and a closed loop driving circuit module 5 and a compensation coil selection module 1 are sequentially arranged on the current loop;
the closed loop driving circuit module 5 is further provided with an analog/digital processing module 6 and a CPU processing module 7, the analog/digital processing module 6 is connected with the CPU processing module 7, and the CPU processing module 7 is connected with the output module.
In a preferred embodiment of the present invention, the number of the compensation coils is at least 3, and the compensation coils are respectively a first compensation coil 2, a second compensation coil 11 and a third compensation coil 12, the current range of the first compensation coil 2 is 0 to 10mA, the current range of the second compensation coil 11 is 10mA to 1A, and the current range of the third compensation coil 12 is 1A to 100A.
As a preferred embodiment of the present invention, the compensation coil selection modules 1 are used to connect/disconnect a current loop between the compensation coil and the hall sensor 10, and the number of the compensation coil selection modules 1 corresponds to the number of the compensation coils one to one.
As a preferred embodiment of the present invention, the number of the closed loop driving circuit modules 5 corresponds to the number of the compensation coils, and a plurality of the closed loop driving circuit modules 5 are connected in parallel with the terminals of the hall sensor 10.
As a preferred embodiment of the present invention, an automatic early warning module 13 is further disposed in the closed-loop driving circuit module 5, and when a circuit passing through the closed-loop driving circuit module 5 exceeds a measurement range, the automatic early warning module 13 transmits alarm information to the CPU processing module 7.
As a preferred embodiment of the present invention, the output module at least includes an Ethernet interface 8 and a fiber interface 9, and the Ethernet (Ethernet) refers to a baseband lan specification created by Xerox corporation and jointly developed by Xerox, Intel and DEC corporation, which is the most common communication protocol standard adopted by the existing lan today. Ethernet networks use CSMA/CD (carrier sense multiple access and collision detection) technology and operate on multiple types of cables at a rate of 10M/S. Ethernet is similar to the IEEE802.3 family of standards; including standard ethernet (10Mbit/s), fast ethernet (100Mbit/s) and 10G (10Gbit/s) ethernet. They are both IEEE802.3 compliant; the optical fiber is a short word of an optical fiber, is a fiber made of glass or plastic and can be used as a light transmission tool. The principle of transmission is 'total reflection of light'; both of the above two types are data transmission ports which transmit faster data at the present time.
As a preferred embodiment of the present invention, the hall sensor 10 is a magnetic balance type current sensor, specifically, the magnetic balance type current sensor is also called a hall closed loop current sensor, also called a compensation type sensor, that is, a magnetic field generated by the current Ip of the main loop at the magnetic flux gathering ring passes through a secondary coil, and the magnetic field generated by the current compensates, so that the hall device is in a working state of detecting zero magnetic flux.
As a preferred embodiment of the present invention, the closed-loop driving circuit module 5 includes a conditioning circuit module 14, a coil driving module 15 and a sampling amplifying module 16, an input end of the conditioning circuit module 14 is connected to a terminal of the hall sensor 10, an output end of the conditioning circuit module 14 is connected to an input end of the coil driving module 15, and an output end of the coil driving module 15 is connected to the compensation coil selecting module 1.
As a preferred embodiment of the present invention, a resistor Rs is disposed on a connection circuit between the coil driving module 15 and the compensation coil selection module 1, and the sampling amplification module 16 is connected in parallel with the resistor Rs.
As a preferred embodiment of the present invention, the sampling amplification module 16 is used to measure and amplify the differential pressure V at Rs and to transfer the differential pressure V information to the analog/digital processing module 6.
Specifically, the magnetic core selects C-shaped magnetic core 4, which not only reflects the magnetic field generated by the power supply cable 3 when the power supply cable is powered on, but also facilitates the setting of hall sensor 10 at the air gap of C-shaped magnetic core 4, a plurality of compensation coils with a certain turn ratio are wound on C-shaped magnetic core 4, a current loop is arranged between the compensation coils and hall sensor 10, and the current loop mainly plays two roles: 1. measuring the current generated by the Hall sensor 10, and when the current exceeds the maximum range of the current closed-loop driving circuit module 5, the automatic early warning module 13 transmits warning information to the CPU processing module 7, and when the current does not exceed the maximum range, the closed-loop driving circuit does not respond, if more than 2 non-responsive closed-loop driving circuits exist at the same time, the closed-loop driving circuit with the minimum range is selected to connect the compensating coil selection module 1 of the corresponding circuit, the compensating coil selection modules 1 of other circuits are kept disconnected, the 2 nd function can be started, so that the compensating coil is electrified to generate a magnetic field opposite to the magnetic field generated by the power supply cable 3, and the magnetic field are mutually counteracted, until the magnetic flux of the hall sensor 10 is 0, at this time, a differential pressure V is formed at the resistor Rs, the sampling amplification module measures and amplifies the differential pressure V and transmits the differential pressure V to the analog/digital processing module 6, the analog/digital processing module 6 is an AD conversion circuit, a corresponding compensation current value can be obtained by using an ohm law and is transmitted to the CPU processing unit, and the CPU processing unit calculates a current value of the leakage current in the power supply cable 3 according to a certain proportional relation and transmits the current value to an upper computer or other monitoring platform through the output module.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts a closed-loop control mode, utilizes the compensating coil to provide driving current to counteract magnetic flux change caused by leakage current, and finishes the sampling of the leakage current by measuring the voltage at two ends of the resistor Rs. In consideration of the amplitude change of leakage current in reality, aiming at ensuring the measurement precision and accuracy, the invention designs a compensation sampling circuit with three current measurement ranges (0-10 mA, 10 mA-1A and 1A-100A), and switches to a proper measurement channel according to the actual value of the leakage current to finish the measurement of the leakage current. The acquired measured value is transmitted to a CPU processing module 7 through an analog/digital processing module 6 and is transmitted to an external upper computer or other monitoring platforms in a digital quantity form through an Ethernet port and an optical fiber interface 9, so that the conversion of leakage current from analog quantity to digital quantity is realized; the invention can not only accurately measure the value of the leakage current, but also ensure the reliability of the measurement result by transmitting in a digital quantity form, provide favorable assistance for the rail maintenance work, improve the working efficiency of subway maintenance personnel and save the cost. The three-range automatic switching can overcome the defects of insufficient range or insufficient measurement precision in most existing schemes, and has wider applicability.
Example 1:
in the embodiment of the invention, the number of the compensation coils is 3, the compensation coils are respectively a first compensation coil 2, a second compensation coil 11 and a third compensation coil 12, the current range of the first compensation coil 2 is 0-10 mA, the current range of the second compensation coil 11 is 10-1A, the current range of the third compensation coil 12 is 1-100A, and the three compensation coils comprise ports 1A and 1 b; 2a, 2 b; 3a and 3b, the ports are arranged at one end of the compensation coil selection module 1, the make-and-break of the ports is controlled by the compensation coil selection module 1, and the other end of the compensation coil selection module 1 is provided with three closed-loop driving circuit modules 5 corresponding to the ports one to one.
When the multi-range contact net leakage current detection device works, the power supply cable 3 needs to penetrate through the center position of the C-shaped magnetic core 4, if leakage current passes through the power supply cable 3, a magnetic field is formed in the C-shaped magnetic core 4, the Hall sensor 10 at the air gap position outputs induced current under the action of the magnetic field, and the current flows into the conditioning circuits in the three closed-loop driving circuit modules 5. If the current exceeds the range of the channel, the automatic early warning module 13 will send an alarm signal to the CPU processing module 7, and if more than 2 closed-loop driving circuit modules 5 do not display an alarm, the closed-loop driving circuit module 5 with the smallest range is preferentially selected. And the compensation coil selection module 1 is communicated with a switch of a corresponding channel to ensure that the corresponding compensation coil and a closed loop driving circuit form a loop, and the remaining four compensation coil terminals are kept in a disconnected state. The coil compensation current generated after modulation and amplification enters the compensation coil through a compensation coil terminal (1a/1b or 2a/2b or 3a/3c) after passing through a resistor Rs. When a compensation current passes through the compensation coil, a magnetic field is generated on the C-shaped magnetic core 4, and the magnitude of the compensation current is adjusted to make the magnetic field equal to and opposite to the magnetic field generated by the leakage current in the power supply cable 3, that is, the magnetic flux passing through the hall sensor 10 is zero. At this time, the magnitude of the compensation current can be reflected by measuring the voltage at the two ends of Rs, and the magnitude of the leakage current in the power supply cable 3 can be calculated according to a certain proportion. The current accurately uploads the leakage current value to an upper computer or other monitoring platforms through an Ethernet interface and/or an optical fiber interface 9.
In the drawings, the positional relationships are depicted for illustrative purposes only and are not to be construed as limiting the present patent; it should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (5)
1. The multi-range contact net leakage current detection device is characterized by comprising a C-shaped magnetic core (4), wherein a power supply cable (3) of a detected contact net penetrates through the center position of the C-shaped magnetic core (4), a Hall sensor (10) is arranged at an air gap of the C-shaped magnetic core (4), a compensation coil is wound on the C-shaped magnetic core (4), a current loop is arranged between the compensation coil and the Hall sensor (10), and a closed-loop driving circuit module (5) and a compensation coil selection module (1) are sequentially arranged on the current loop;
The closed loop driving circuit module (5) is also respectively provided with an analog/digital processing module (6) and a CPU processing module (7), the analog/digital processing module (6) is connected with the CPU processing module (7), and the CPU processing module (7) is connected with the output module;
the closed-loop driving circuit module (5) comprises a conditioning circuit module (14), a coil driving module (15) and a sampling amplification module (16), wherein the input end of the conditioning circuit module (14) is connected with the wiring terminal of the Hall sensor (10), the output end of the conditioning circuit module (14) is connected with the input end of the coil driving module (15), and the output end of the coil driving module (15) is connected with the compensation coil selection module (1);
a resistor Rs is arranged on a connecting circuit of the coil driving module (15) and the compensation coil selection module (1), and the sampling amplification module (16) is connected with the resistor Rs in parallel;
the number of the compensation coils is at least 3, the current measuring ranges of a plurality of compensation coils are different, the compensation coil selection module (1) is used for connecting/disconnecting a current loop between the compensation coils and the Hall sensor (10), the number of the compensation coil selection module (1) corresponds to the number of the compensation coils one by one, the number of the closed loop driving circuit modules (5) corresponds to the number of the compensation coils one by one, and the closed loop driving circuit modules (5) are connected with the wiring terminals of the Hall sensor (10) in parallel;
An automatic early warning module (13) is further arranged in the closed-loop driving circuit module (5), the Hall sensor (10) at the air gap position can output induced current under the action of a magnetic field, and the induced current flows into a plurality of conditioning circuits in the closed-loop driving circuit module (5); when the induced current exceeds the measuring range through the circuit of the closed loop driving circuit module (5), the automatic early warning module (13) transmits alarm information to the CPU processing module (7);
if more than 2 closed loop driving circuit modules (5) do not display the alarm, the closed loop driving circuit module (5) with the minimum range is preferentially selected.
2. The multi-range catenary leakage current detection device according to claim 1, wherein the compensation coils are respectively a first compensation coil (2), a second compensation coil (11) and a third compensation coil (12), the current range of the first compensation coil (2) is 0-10 mA, the current range of the second compensation coil (11) is 10-1A, and the current range of the third compensation coil (12) is 1-100A.
3. The multi-range catenary leakage current detection device according to claim 1, wherein the output module at least comprises an ethernet interface (8) and an optical fiber interface (9).
4. The multirange catenary leakage current detection device of claim 1, wherein the hall sensor (10) is a magnetic balance type current sensor.
5. A multirange catenary leakage current detection device according to claim 1, characterized in that the sampling and amplifying module (16) is used to measure and amplify the differential pressure V at Rs and to transfer the differential pressure V information to the analog/digital processing module (6).
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