Insulator leakage current acquisition and measurement device and method based on skin effect

Abstract

The invention relates to the technical field of insulator leakage current measurement, and provides an insulator leakage current acquisition and measurement device and method based on a skin effect, a self-tapping sensing screw is directly nailed into an insulator steel cap to acquire a leakage current signal, the installation process is simplified, and high adaptability is achieved. On the basis that power frequency current in actual use is used as calibration current, the shunt ratio can be accurately calibrated, actual leakage current signals can be accurately measured through current signals collected by an embedded shunt current sensor by means of the skin effect, the sensitivity and accuracy of measurement are ensured, and the reliability of the device is improved. And potential faults can be effectively warned.

Description

Technical Field

[0001] The invention relates to the technical field of insulator leakage current measurement, and in particular to an insulator leakage current acquisition and measurement device and method based on skin effect. Background Art

[0002] With the continuous development of power systems, the issue of safe and stable operation has received more and more attention. Insulators are important components that play a role in mechanical connection support and electrical insulation for electrical equipment and are an indispensable part of the power system. The insulation performance of insulators directly affects whether the power system can maintain stable operation.

[0003] When the insulation state of the insulator decreases, corresponding phenomena will occur, among which the most common concern is the change in the leakage current flowing through the surface of the insulator, such as the increase in its amplitude and the appearance of high-frequency pulses in the waveform. Therefore, inferring the insulator performance state and discharge risk by monitoring the insulator leakage current is a feasible technical path for insulator state monitoring.

[0004] At present, there are many methods and equipment for monitoring the surface leakage current of insulators in the industry, but they often have defects such as inconvenient installation and insufficient functions, and cannot fully meet the needs of online monitoring of insulator leakage current.

[0005] In summary, the present invention aims at the problems of sensor installation, data processing and transmission for online monitoring of insulator surface leakage current, and provides an insulator leakage current acquisition and measurement device and method based on the skin effect. Summary of the invention

[0006] The purpose of the present invention is to solve the deficiencies of the prior art and to provide an insulator leakage current acquisition and measurement device and method based on the skin effect.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] An insulator leakage current acquisition and measurement device based on skin effect, comprising a leakage current detection sensor device, a data processing device and a calibration device;

[0009] The leakage current detection sensor device comprises a self-tapping sensor screw and a shielded wire, wherein the self-tapping sensor screw is driven into the surface of the steel cap of the insulator sheet, and one end of the shielded wire is electrically connected to the self-tapping sensor screw and the other end is electrically connected to the input end of the data processing device;

[0010] The data processing device includes a current conversion module, a microprocessor, a wireless communication module and a power supply module. The current conversion module performs I / V conversion on the leakage current signal input by the shielded wire. The microprocessor is used to process the converted voltage signal. The microprocessor performs analog-to-digital conversion and storage packaging compression on the voltage signal, and transmits the compressed data packet to the remote platform through the wireless communication module.

[0011] The calibration device comprises a current source module and two connecting leads, wherein the two leads form a current loop between the current source module and the insulator, and the current source module applies a power frequency current to the insulator.

[0012] Preferably, the industrial frequency alternating current applied by the current source module of the calibration device is an alternating current of 50 Hz and 1 mA.

[0013] Preferably, the self-tapping sensor screw is embedded with a shunt current sensor, and an output end of the shunt current sensor is electrically connected to the shielded wire.

[0014] Preferably, the shielded conductor is made of copper or aluminum non-magnetic material.

[0015] Preferably, the power supply module is powered by a battery solar module.

[0016] Preferably, the current conversion module, microprocessor and wireless communication module of the data processing device are integrated on the same PCB circuit board, the microprocessor adopts an STM32 processor, and the wireless communication module supports dual-mode communication and has two communication modes: 4G and NB-IoT.

[0017] Preferably, the data processing device is installed inside a chassis, and the chassis is installed on a tower pole.

[0018] Another object of the present invention is to provide a method for collecting and measuring insulator leakage current based on skin effect, comprising the following steps:

[0019] S1. Calibrate the shunt ratio. After the leakage current detection sensor device and the data processing device are initially installed, apply the power frequency current to the insulator through the calibration device, and use the ratio of the applied power frequency current value to the current value output by the data processing device to obtain the shunt ratio n. After the shunt ratio is obtained, input the shunt ratio information into the data processing device, and finally remove the calibration device.

[0020] S2. Leakage current measurement:

[0021] S2.1. Obtain leakage current signal. When AC leakage current flows through the steel cap of the insulator, due to the skin effect of AC current in the metal, the shunt current sensor in the self-tapping sensor screw nailed into the surface of the steel cap can measure the leakage current signal flowing through.

[0022] S2.2, leakage current signal conversion, the leakage current signal measured by the shunt current sensor is transmitted to the current conversion module of the data processing device through the shielded wire, and the current conversion module converts the signal into a voltage signal that can be read by the microprocessor and then transmits it to the microprocessor;

[0023] S2.3, get the real current value. After the microprocessor receives the leakage current signal, the microprocessor sets the shunt ratio to 1 by default. After calibration, the actual shunt ratio is used to overwrite the original shunt ratio. The calibrated shunt ratio n and the measured current value I 测 Calculate the actual leakage current value I 真实 , through formula I 真实 =n×I 测 Get the real leakage current value and store it temporarily;

[0024] S2.4, data transmission, the microprocessor controls the wireless communication module to send the temporarily stored real leakage current value to the remote platform current value through the wireless communication module.

[0025] Preferably, the split ratio calibration comprises the following steps:

[0026] S1.1. Ensure that the line conductor suspended by the insulator is de-energized, and install the leakage current detection sensor device and data processing device on the tower;

[0027] S1.2, prepare to calibrate the split ratio n;

[0028] S1.3. Pull out the two leads of the current source module from the device and connect them to the steel cap of the top piece and the steel foot of the bottom piece of the insulator string respectively;

[0029] S1.4. After connecting the leads, turn on the current source module and input a 50Hz power frequency alternating current with an amplitude of 1mA into the insulator string;

[0030] S1.5, at this time the current value I is measured 测 , and according to the formula

[0031]

[0032] Calculate the split ratio n, where I 真 =1mA; after obtaining the split ratio, input the split ratio information into the microprocessor;

[0033] S1.6. Turn off the current source, remove the two leads of the current source module from the insulator string, and retract the calibration device.

[0034] The present invention discloses an insulator leakage current acquisition and measurement device based on skin effect, which has the following beneficial effects.

[0035] The present invention uses self-tapping sensor screws to directly drive into the insulator steel cap, which simplifies the installation process and has strong adaptability. Based on the actual power frequency current used as the calibration current, the shunt ratio can be accurately calibrated. By using the skin effect, the current signal collected by the shunt current sensor can be used to accurately measure the actual leakage current signal through the embedded shunt current sensor, ensuring the sensitivity and accuracy of the measurement and effectively warning of potential faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is an overall schematic diagram of the insulator leakage current collection and measurement device based on the skin effect of the present invention.

[0037] Figure 2 The figure is a schematic diagram of the principle of the insulator leakage current collection and measurement device based on the skin effect of the present invention.

[0038] Figure 3 The figure is a flow chart of the split ratio calibration method of the present invention.

[0039] Figure 4 It is a connection diagram of the calibration device of the present invention.

[0040] Figure 5 This is a schematic diagram of the installation of the self-tapping sensor screw of the present invention.

[0041] Figure 6 The present invention is a flow chart of the insulator leakage current collection and measurement method based on the skin effect.

[0042] In the attached drawings: 1. leakage current detection sensor device; 11. self-tapping sensor screw; 12. shielded wire; 2. data processing device; 21. current conversion module; 22. microprocessor; 23. wireless communication module; 24. power supply module; 241. battery; 242. solar module power supply; 3. insulator; 4. remote platform; 5. calibration device; 51. lead wire. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0044] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0045] Example 1

[0046] Please refer to Figure 1 and Figure 2 , an insulator 3 leakage current measuring device based on skin effect, comprising a leakage current detection sensor device 1, a data processing device 2 and a calibration device 5;

[0047] The leakage current detection sensor device 1 includes a self-tapping sensor screw 11 and a shielded wire 12. Figure 5 As shown, the self-tapping sensor screw 11 is driven into the steel cap surface of the insulator 3, and the leakage current signal after shunting can be obtained by using the skin effect of the AC leakage current. One end of the shielded wire 12 is electrically connected to the self-tapping sensor screw 11 and the other end is electrically connected to the input end of the data processing device 2, and the leakage current signal is transmitted to the data processing device 2; preferably, the self-tapping sensor screw 11 is embedded with a shunt current sensor, and the output end of the shunt current sensor is electrically connected to the shielded wire 12. The shielded wire 12 is made of copper and aluminum non-magnetic materials. The shunt current sensor model is Taiwan Boji 7550A high-precision shunt.

[0048] The data processing device 2 includes a current conversion module 21, a microprocessor 22, a wireless communication module 23 and a power supply module 24. The current conversion module 21 converts the current signal detected by the leakage current detection sensor part into a voltage signal that can be read and processed by the microprocessor 22, that is, the leakage current signal input by the shielded wire 12 is converted into I / V. The microprocessor 22 is used to process the converted voltage signal. The microprocessor 22 performs analog-to-digital conversion and storage packaging compression on the voltage signal, reads and stores the data, and transmits the data to the remote platform through the wireless communication module 23;

[0049] The calibration device 5 includes a current source module and two connecting leads 51, such as Figure 4 As shown, two leads 51 form a current loop between the current source module and the insulator 3, and the current source module applies a power frequency current to the insulator 3. The power frequency alternating current applied by the current source module of the calibration device 5 is an alternating current of 50Hz and 1mA. The power frequency alternating current is used to provide a known reference current so that the data processing device 2 can calculate the shunt ratio of the leakage current detection device by measuring the output current signal of the leakage current detection device.

[0050] The power supply module 24 uses a solar module 242 in combination with a battery 241. The solar module receives sunlight to generate electricity, and the excess electrical energy is stored in the battery 241, thereby achieving all-weather continuous power supply to the equipment.

[0051] The current conversion module 21, microprocessor 22, and wireless communication module 23 of the data processing device 2 are integrated on the same PCB circuit board. The data processing device 2 is installed inside the chassis, and the chassis is installed on the tower through clamps and bolts. The chassis is used to isolate dirt and precipitation. The microprocessor 22 uses an STM32 processor, and the wireless communication module 23 supports dual-mode communication. It is an Ankerui AWT100 wireless communication terminal with two communication modes: 4G and NB-IoT.

[0052] Example 2

[0053] Based on Example 1, this embodiment provides a method for measuring leakage current of an insulator 3 based on skin effect. Please refer to Figure 6 , a method for measuring leakage current of an insulator 3 based on skin effect, comprising the following steps:

[0054] S1, calibrate the shunt ratio; after the leakage current detection sensor device 1 and the data processing device 2 are initially installed, apply the power frequency current to the insulator 3 through the calibration device 5, and use the ratio of the applied power frequency current value to the current value output by the data processing device 2 to obtain the shunt ratio n; after obtaining the shunt ratio, input the shunt ratio information into the data processing device 2, and finally remove the calibration device 5;

[0055] It is worth mentioning that the steel cap and the steel foot are both metal conductors, and there is a skin effect in high-frequency currents in metal conductors, that is, when there is alternating current or alternating electromagnetic field in the conductor, the current distribution inside the conductor is uneven, and the current is concentrated in the "skin" part of the conductor, that is, the current is concentrated in the thin layer on the surface of the conductor. The closer to the surface of the conductor, the greater the current density, and the actual current inside the conductor is smaller. Therefore, you only need to use a screwdriver to rotate the self-tapping sensor screw into a certain place on the surface of the steel cap of any insulator 3 in the insulator 3 string, and there is no need to drill too deep, such as Figure 5 shown. Figure 5 In the figure, the arrow indicates the path of the alternating current flowing from the high-voltage conductor to the tower (ground potential). The alternating current will only flow on the surface of the insulator 3 and inside the steel cap, so the self-tapping sensor screw can be installed in this way to collect the leakage current waveform data after the shunt. Since the self-tapping screw sensor can only collect the leakage current component flowing through the screw position instead of the entire leakage current after being nailed into the steel cap of the insulator 3, the structure is actually a current shunt. There is a proportional relationship between the sensor and the measured current and the total current value, so the proportional relationship needs to be measured through calibration, and the shunt ratio is related to the shape of the insulator 3 string, the installation position of the self-tapping screw, the drilling depth, etc. After the equipment is installed, the shunt ratio n will not change as long as the installation position of the self-tapping screw sensor is not changed.

[0056] S2. Leakage current measurement:

[0057] S2.1. Obtaining leakage current signal. When AC leakage current flows through the steel cap of the insulator 3, due to the skin effect of AC current in the metal, the shunt current sensor nailed into the self-tapping sensor screw 11 on the surface of the steel cap can measure the leakage current signal flowing through;

[0058] S2.2, leakage current signal conversion, the leakage current signal measured by the shunt current sensor is transmitted to the current conversion module 21 of the data processing device 2 through the shielded wire 12, and the current conversion module 21 converts the signal into a voltage signal that can be read by the microprocessor 22 and then transmits it to the microprocessor 22;

[0059] S2.3, obtaining the real current value. After the microprocessor 22 receives the leakage current signal, the microprocessor 22 sets the shunt ratio to 1 by default. After calibration, the actual shunt ratio is used to overwrite the original shunt ratio. The calibrated shunt ratio n and the measured current value I 测 Calculate the actual leakage current value I 真实 , through formula I 真实 =n×I 测 Get the real leakage current value and store it temporarily;

[0060] S2.4, data transmission, the microprocessor 22 controls the wireless communication module 23 to send the temporarily stored real leakage current value to the remote platform 4 current value through the wireless communication module 23;

[0061] Please refer to Figure 3 , the split ratio calibration includes the following steps:

[0062] S1.1. Ensure that the line conductor suspended by the insulator 3 is de-energized, and install the leakage current detection sensor device 1 and the data processing device 2 on the tower;

[0063] S1.2, prepare to calibrate the split ratio n;

[0064] S1.3, pull out the two leads 51 of the current source module from the device and connect them to the steel cap of the top piece and the steel foot of the bottom piece of the three strings of insulators respectively;

[0065] S1.4. After connecting the lead 51, turn on the current source module to input a 50 Hz power frequency alternating current with an amplitude of 1 mA to the three strings of insulators;

[0066] S1.5. At this time, the current value I is measured, and according to the formula

[0067]

[0068] Calculate the split ratio n, where I 真 =1mA; after obtaining the split ratio, input the split ratio information into the microprocessor;

[0069] S1.6. Turn off the current source, remove the two leads 51 of the current source module from the string of insulators 3, and retract the calibration device 5.

[0070] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The substitution may be a substitution of a part of the structure, device, method step, or a complete technical solution. The equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. An insulator leakage current acquisition and measurement device based on skin effect, characterized in that: include: Leakage current detection sensor device, data processing device and calibration device; The leakage current detection sensor device comprises a self-tapping sensor screw and a shielded wire, wherein the self-tapping sensor screw is driven into the surface of the steel cap of the insulator sheet, and one end of the shielded wire is electrically connected to the self-tapping sensor screw and the other end is electrically connected to the input end of the data processing device; The data processing device includes a current conversion module, a microprocessor, a wireless communication module and a power supply module. The current conversion module performs I / V conversion on the leakage current signal input by the shielded wire. The microprocessor is used to process the converted voltage signal. The microprocessor performs analog-to-digital conversion and storage packaging compression on the voltage signal, and transmits the compressed data packet to the remote platform through the wireless communication module. The calibration device comprises a current source module and two connecting leads, wherein the two leads form a current loop between the current source module and the insulator, and the current source module applies a power frequency current to the insulator.

2. The insulator leakage current acquisition and measurement device based on skin effect according to claim 1, characterized in that: The industrial frequency alternating current applied by the current source module of the calibration device is an alternating current of 50 Hz and 1 mA.

3. The insulator leakage current acquisition and measurement device based on skin effect according to claim 1, characterized in that: The self-tapping sensing screw is embedded with a shunt current sensor, and an output end of the shunt current sensor is electrically connected to the shielded wire.

4. The insulator leakage current acquisition and measurement device based on skin effect according to claim 3, characterized in that: The shielded conductor is made of copper or aluminum non-magnetic materials.

5. The insulator leakage current acquisition and measurement device based on skin effect according to claim 1, characterized in that: The power supply module is powered by a battery-solar module.

6. The insulator leakage current acquisition and measurement device based on skin effect according to claim 1, characterized in that: The current conversion module, microprocessor and wireless communication module of the data processing device are integrated on the same PCB circuit board. The microprocessor adopts an STM32 processor, and the wireless communication module supports dual-mode communication and has two communication modes: 4G and NB-IoT.

7. The insulator leakage current acquisition and measurement device based on skin effect according to claim 1, characterized in that: The data processing device is installed inside a chassis, and the chassis is installed on a tower pole.

8. A measuring method for collecting and measuring insulator leakage current based on skin effect according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, calibrate the split ratio; After the leakage current detection sensor device and the data processing device are initially installed, the power frequency current is applied to the insulator through the calibration device, and the shunt ratio n is obtained by using the ratio of the applied power frequency current value to the current value output by the data processing device; after the shunt ratio is obtained, the shunt ratio information is input into the data processing device, and finally the calibration device is removed; S2. Leakage current measurement: S2.

1. Obtain leakage current signal. When AC leakage current flows through the steel cap of the insulator, due to the skin effect of AC current in the metal, the shunt current sensor in the self-tapping sensor screw nailed into the surface of the steel cap can measure the leakage current signal flowing through. S2.2, leakage current signal conversion, the leakage current signal measured by the shunt current sensor is transmitted to the current conversion module of the data processing device through the shielded wire, and the current conversion module converts the signal into a voltage signal that can be read by the microprocessor and then transmits it to the microprocessor; S2.3, get the real current value. After the microprocessor receives the leakage current signal, the microprocessor sets the shunt ratio to 1 by default. After calibration, the actual shunt ratio is used to overwrite the original shunt ratio. The calibrated shunt ratio n and the measured current value I 测 Calculate the actual leakage current value I 真实 , through formula I 真实 =n×I 测 Get the real leakage current value and store it temporarily; S2.4, data transmission, the microprocessor controls the wireless communication module to send the temporarily stored real leakage current value to the remote platform current value through the wireless communication module.

9. The insulator leakage current collection and measurement method according to claim 8, characterized in that: The split ratio calibration comprises the following steps: S1.

1. Ensure that the line conductor suspended by the insulator is de-energized, and install the leakage current detection sensor device and data processing device on the tower; S1.2, prepare to calibrate the split ratio n; S1.

3. Pull out the two leads of the current source module from the device and connect them to the steel cap of the top piece and the steel foot of the bottom piece of the insulator string respectively; S1.

4. After connecting the leads, turn on the current source module and input a 50Hz power frequency alternating current with an amplitude of 1mA into the insulator string; S1.5, at this time the current value I is measured 测 , and according to the formula Calculate the split ratio n, where I 真 =1mA; after obtaining the split ratio, input the split ratio information into the microprocessor; S1.

6. Turn off the current source, remove the two leads of the current source module from the insulator string, and retract the calibration device.

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