Insulator leakage current detection device and method based on quantum weak magnetic field sensing

Abstract

The invention discloses an insulator leakage current detection device and method based on quantum weak magnetic field sensing, and the device comprises a semiconductor laser, a dichroscope, an optical fiber collimator, a quantum sensor, a photomultiplier, a data collection card, and a computer, and the quantum sensor comprises a PCB, and a microwave source, a microwave antenna, and a diamond NV color center which are disposed on the PCB. The diamond NV color center is located in the excitation range of the microwave antenna, pulse laser emitted by the semiconductor laser passes through the dichroscope and then enters the optical fiber collimator, the optical fiber collimator is connected with the diamond NV color center through an optical fiber, the photomultiplier is located on a reflection light path of the dichroscope, and the photomultiplier is connected with the computer through the data acquisition card. According to the insulator leakage current detection device and detection method based on quantum weak magnetic field sensing, the detection sensitivity is high, the deterioration condition of the insulator can be timely and effectively found, and the situation that the normal operation of a power system is affected by major accidents is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of insulator fault detection, and in particular to an insulator leakage current detection device based on quantum weak magnetic field sensing. Background Art

[0002] The detection of the insulation status of insulators is of great significance in overhead transmission lines, equipment support and insulation in substations, contact network systems, and communication line tower supports. Due to long-term accumulation of dirt, moisture, condensation, and mechanical stress, the insulation performance is reduced, resulting in insulator degradation, which is manifested macroscopically as an increase in leakage current. When an insulator deteriorates, it may cause a chain reaction through electromagnetic coupling, overvoltage transmission, etc. If the staff accidentally touches the live part, it will cause an electric shock accident. Therefore, it is crucial to detect insulator degradation in a timely manner and prevent the damage caused by insulator degradation from gradually expanding, which is crucial to protecting the safe operation of the power system.

[0003] At present, the main methods for detecting insulator degradation in power systems include electrical measurement methods such as insulation resistance measurement, distributed voltage measurement, and AC withstand voltage test, as well as non-electrical measurement methods such as ultrasonic detection and laser Doppler vibration. Although these methods can detect defects and faults inside insulators to a certain extent, some of the above methods require contact measurement after power failure, and the sensitivity of online measurement technology is difficult to detect early insulation degradation. Comprehensive analysis shows that the existing insulator degradation detection methods have problems such as difficulty in real-time online monitoring, low measurement accuracy, and poor detection effect.

[0004] When the insulator insulation deteriorates, it is often accompanied by changes in leakage current. If the insulator leakage current data can be monitored in real time, potential faults can be discovered immediately before the insulator disintegrates and countermeasures can be taken to avoid power outages and reduce economic losses. The basic principle of the method of directly detecting the leakage current to determine the insulation state of the insulator is that the leakage current in the insulation will change after the insulator deteriorates. According to the Ampere loop theorem, the current change causes the magnetic field to change, and we have:

[0005]

[0006] Furthermore, according to the Biot-Savart law:

[0007]

[0008] Where L is any closed curve; I is the total current passing through the so-called surface; μ 0is the vacuum magnetic permeability; r is the distance from the measuring point to the inferior insulator; θ is the angle between the current element and the vector pointing to the measuring point. Therefore, by measuring the magnetic field strength, the insulator leakage current can be detected, and the insulation performance of the insulator can be further judged. This method is indeed a feasible method that can truly realize insulator degradation monitoring, but because the insulation leakage current is generally a weak magnetic field signal at the microampere level, the existing sensing technology is not sensitive enough to the microampere current magnetic field, and early insulation latency is difficult to detect, which cannot fully meet the needs of insulator fault monitoring. Summary of the invention

[0009] The purpose of the present invention is to provide an insulator leakage current detection device and detection method based on quantum weak magnetic field sensing, which has high detection sensitivity and can timely and effectively detect the occurrence of insulator degradation, thereby avoiding major accidents that affect the normal operation of the power system.

[0010] To achieve the above-mentioned purpose, the present invention provides an insulator leakage current detection device based on quantum weak magnetic field sensing, comprising a semiconductor laser, a dichroic mirror, an optical fiber collimator, a quantum sensor, a photomultiplier tube, a data acquisition card, and a computer. The quantum sensor comprises a PCB board and a microwave source, a microwave antenna, and a diamond NV color center arranged on the PCB board. The diamond NV color center is located within the excitation range of the microwave antenna. The pulse laser emitted by the semiconductor laser passes through the dichroic mirror and then enters the optical fiber collimator. The optical fiber collimator is connected to the diamond NV color center through an optical fiber. The photomultiplier tube is located on the reflected light path of the dichroic mirror. The photomultiplier tube is connected to the computer through the data acquisition card.

[0011] Preferably, the microwave source is connected to the radio frequency source, the microwaves emitted by the microwave source cover the microwave antenna, and the microwave source generates microwaves with a frequency scanning accuracy of 1kHz, an output power of 2-8dBm, and a frequency range of 2.0-3.5GHz.

[0012] Preferably, the power of the semiconductor laser is 10 mW, the wavelength is 532 nm, and the modulation mode of the laser pulse is TTL modulation.

[0013] Preferably, a short-wavelength dichroic mirror made of fused quartz is used, the cutoff wavelength of the dichroic mirror is in the range of 550nm-605nm, and the transmittance and reflectivity of light with a wavelength shorter than 550nm or longer than 605nm are both greater than 90%.

[0014] Preferably, the optical fiber collimator is composed of a single-core multimode optical fiber pigtail with a central wavelength of 780 nm and an ultraviolet fused silica lens with a lens diameter of 5 mm, a focal length of 5-10 mm, and a wavelength of 185-2500 nm.

[0015] Preferably, the optical fiber is a multimode optical fiber with a diameter of 125 μm, and the end of the optical fiber is fixedly connected to the diamond NV color center by epoxy glue.

[0016] Preferably, the radius of the diamond NV color center is between 10 nm and 20 μm.

[0017] Preferably, the output form of the photomultiplier tube is voltage, the detection range of the photomultiplier tube is 300-850nm weak light, and the sensitivity is greater than 3.4×10 7 V / lm.

[0018] Preferably, the data acquisition card adopts a USB2.0 interface acquisition card with 24-bit precision.

[0019] The detection method of the insulator leakage current detection device based on quantum weak magnetic field sensing, the steps are as follows:

[0020] S1. Place the quantum sensor near the insulator to be measured, turn on the laser to generate pulsed laser, and the pulsed laser enters the fiber collimator after passing through the dichroic mirror. The fiber collimator converts the incident pulsed laser into collimated light, which is then emitted through the optical fiber to the diamond NV color center. The NV color center undergoes energy level transition under the excitation of 532nm green light and emits red fluorescence. The stimulated red fluorescence is reflected back to the dichroic mirror along the optical fiber and then enters the photomultiplier tube. The photomultiplier tube receives photons and converts them into voltage amplitude output;

[0021] S2. At the same time, the microwave source on the PCB generates a microwave signal driven by the radio frequency source, and the diamond NV color center is regulated by the microwave antenna. The red fluorescence intensity generated by the excited NV color center changes with the microwave frequency. The microwave frequency is adjusted to quickly sweep in the range of 2.0-3.5 GHz to obtain a spectrum with the horizontal axis being the microwave frequency and the vertical axis being the NV color center fluorescence intensity.

[0022] S3, using a data acquisition card to quickly collect the voltage signal of the photomultiplier tube, and obtaining a light detection magnetic resonance spectrum through computer processing, wherein the light detection resonance spectrum is a splitting spectrum with two troughs, and the highest light intensity point between the two troughs is defined as the central frequency of the spectrum line;

[0023] S4. Select the initial splitting spectrum center frequency in the optical detection magnetic resonance spectrum as the zero starting point. When an external magnetic field acts on the color center, the fluorescence spectrum of the NV color center will shift with the magnetic field strength. By calculating the shift value of the center frequency point of the splitting spectrum, the magnitude of the magnetic field strength can be immediately inferred through a linear relationship.

[0024] S5. The quantum sensor placed near the insulator calculates the magnetic field change at the test position based on the relationship between the magnetic field strength and the zero-field splitting center frequency, and compares whether the magnetic field strength exceeds the safety threshold. If the magnetic field strength exceeds the safety threshold, the leakage current is greater than the safety threshold, indicating that the insulator has deteriorated.

[0025] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] The diamond NV color center quantum sensor senses the change of weak magnetic field around the insulator, collects the light signal through the photomultiplier tube, and expresses the change of current in the form of optical detection magnetic resonance spectrum. After testing, it has a sensitivity of 0.3-0.5μA, which is enough to detect the early insulation latency of insulator degradation.

[0027] The components are simple, the cost is low, and the test is convenient. When the parameters are determined in advance, the measurement results can be quickly obtained through the computer, which is convenient for timely detection of the current leakage of the insulator.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 It is a structural schematic diagram of an embodiment of an insulator leakage current detection device based on quantum weak magnetic field sensing of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of a quantum sensor according to an embodiment of the present invention;

[0032] Figure 3 This is a flow chart of an insulator leakage current detection method based on quantum weak magnetic field sensing according to an embodiment of the present invention;

[0033] Figure 4 The optical detection magnetic resonance spectra measured at different operation times of the embodiments of the present invention;

[0034] Figure 5 This is a diagram of the leakage current detection results of the diamond NV color center quantum sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Reference numerals

[0038] 1. PCB board; 2. Microwave antenna; 3. Diamond NV color center; 4. Connector.

[0039] Example

[0040] like Figure 1 As shown, an insulator leakage current detection device based on quantum weak magnetic field sensing includes a semiconductor laser, a dichroic mirror, a fiber collimator, a quantum sensor, a photomultiplier tube, a data acquisition card, and a computer. The pulse laser emitted by the semiconductor laser passes through the dichroic mirror and then enters the fiber collimator. The fiber collimator is connected to the diamond NV color center 3 on the quantum sensor through an optical fiber, and the change of the weak magnetic field intensity around the quantum sensor can be sensitively monitored by measuring the optical detection magnetic resonance (ODMR) spectrum.

[0041] The power of the semiconductor laser is 10mW, the wavelength is 532nm, and the modulation mode of the laser pulse is TTL modulation. A short-wave dichroic mirror made of fused quartz is used, and the reflection surface of the dichroic mirror faces the photomultiplier tube and the fiber collimator. The cut-off wavelength of the dichroic mirror is in the range of 550nm-605nm, and the transmittance and reflectivity of light with a wavelength shorter than 550nm or longer than 605nm are both greater than 90%.

[0042] The fiber collimator consists of a single-core multimode fiber pigtail with a central wavelength of 780nm and a UV fused silica lens with a lens diameter of 5mm, a focal length of 5-10mm, and a wavelength of 185-2500nm. The optical fiber uses a multimode fiber with a diameter of 125μm, and the end of the optical fiber is fixedly connected to the diamond NV color center 3 by epoxy glue.

[0043] The photomultiplier tube is located in the reflected light path of the dichroic mirror. The photomultiplier tube receives the photon signal and amplifies it. Its output is in the form of voltage. The detection range of the photomultiplier tube is 300-850nm weak light, and the sensitivity is greater than 3.4×10 7V / lm. The data acquisition card connected to the photomultiplier tube uses a 24-bit precision USB2.0 interface acquisition card. The photomultiplier tube is connected to the computer through the data acquisition card, and the computer is used to analyze the data and display the detected weak magnetic field strength.

[0044] like Figure 2 As shown, the quantum sensor includes a PCB board 1 and a microwave source, a microwave antenna 2, and a diamond NV color center 3 arranged on the PCB board 1. The radius of the diamond NV color center 3 is between 10nm and 20μm. The diamond NV color center 3 is located within the excitation range of the microwave antenna 2. The microwave source is connected to the radio frequency source through a connector 4, and the microwaves emitted by the microwave source are enveloped on the microwave antenna 2. The microwave source generates microwaves with a frequency scanning accuracy of 1kHz, an output power of 2-8dBm, and a frequency range of 2.0-3.5GHz. The microwave antenna 2 is composed of a 50Ω resistor and a circular copper coil with a diameter of 1-5mm.

[0045] like Figure 3 As shown, the steps of the insulator leakage current detection method based on quantum weak magnetic field sensing are as follows:

[0046] S1. Place the quantum sensor near an insulator in good condition and fix the quantum sensor with an insulating support. Set the laser intensity to 10mW, the laser pulse to a square wave, the single pulse time to 10us, and the duty cycle to 0.5. After turning on the laser, the green light irradiates the NV color center of 15um along the optical fiber. The NV color core undergoes energy level transition under the excitation of 532nm green light and emits red fluorescence. The stimulated red fluorescence is reflected back to the dichroic mirror along the optical fiber and then enters the photomultiplier tube. The photomultiplier tube receives photons and converts them into voltage amplitude output.

[0047] S2. Adjust the microwave source power to 5dBm to transmit microwave signals. The microwave signals are applied to the microwave antenna 2 of the PCB board 1. The diamond NV color center 3 is regulated by the microwave antenna 2. The intensity of the red light generated by the excited NV color center changes with the microwave frequency. The microwave frequency is adjusted to quickly sweep within the range of 2.0-3.5GHz to obtain a spectrum with the microwave frequency as the horizontal axis and the fluorescence intensity of the NV color center as the vertical axis.

[0048] S3. Use a data acquisition card to quickly collect the voltage signal of the photomultiplier tube, and obtain the light detection magnetic resonance spectrum after computer processing. The drawn light detection magnetic resonance spectrum is a split spectrum with two troughs, and the highest light intensity point between the two troughs is defined as the central frequency of the spectrum line.

[0049] S4. Select the initial splitting center frequency in the optical detection magnetic resonance spectrum as the zero starting point, apply an external magnetic field to the color center, and the fluorescence spectrum of the NV color center will shift with the magnetic field strength. By calculating the shift value of the center frequency point of the splitting spectrum, the magnitude of the magnetic field strength can be immediately inferred through a linear relationship. Knowing that a 1-10μA leakage current can generate a 10-100nT magnetic field strength, based on the relationship between the splitting center microwave frequency and the leakage current, it is concluded that the linear relationship is approximately 10KHz / nT. The optical magnetic resonance spectra obtained at different running times are as follows: Figure 4 As shown, the microwave frequency corresponding to the splitting center is obtained according to the optical magnetic resonance spectrum, and the change of the central microwave frequency is calculated to be 353kHz. According to the calibration slope of 10kHz / nT, the change of the magnetic field intensity can be obtained to be 35.3nT, and then the change of the leakage current can be obtained to be 3.53μA.

[0050] S5. The NV color center weak magnetic detection unit placed near the insulator can calculate the magnetic field change at the test position based on the relationship between the magnetic field strength and the zero-field splitting center frequency, and compare whether the magnetic field strength exceeds the safety threshold. If the magnetic field strength exceeds the safety threshold, the leakage current is greater than the safety threshold, indicating that the insulator has deteriorated.

[0051] When detecting weak magnetic fields generated by insulator degradation, NV color center quantum sensors usually show good linearity within a certain range of magnetic field strength. Figure 5 After a lot of experimental tests and data fitting analysis, it is found that when the detected weak magnetic field strength is in the range of 0-100nT, the signal output by the sensor shows a good linear relationship with the actual magnetic field strength. In the above 0-100nT range, the correlation coefficient R 2 It can reach above 0.98, which shows that within this magnetic field strength range, there is a high linear correlation between the sensor output signal and the actual magnetic field strength, and the actual magnetic field strength can be inferred relatively accurately by measuring the output signal, thus providing a reliable basis for accurately judging the degree of insulator degradation. Through previous experimental calibration and theoretical calculations, it was determined that for every 1nT change in magnetic field strength, the corresponding insulator leakage current change is about 0.1μA. Then the magnetic field sensitivity of the NV color center quantum sensor of about 3-5nT can be indirectly deduced that its sensitivity to leakage current is roughly around 0.3-0.5μA.

[0052] The remaining technical features in the above embodiments can be flexibly selected by those skilled in the art according to actual conditions to meet different specific practical needs. However, it is obvious to those skilled in the art that it is not necessary to adopt these specific details to implement the present invention. In other examples, in order to avoid confusing the present invention, the well-known components, structures or parts are not specifically described, which are all within the technical protection scope defined by the technical solution claimed for protection in the claims of the present invention.

[0053] Modifications and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the scope of protection of the claims attached to the present invention. In the above description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details are not necessary to practice the present invention. In other examples, in order to avoid confusing the present invention, well-known technologies, such as specific construction details, operating conditions and other technical conditions, are not specifically described.

[0054] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An insulator leakage current detection device based on quantum weak magnetic field sensing, characterized in that: It includes a semiconductor laser, a dichroic mirror, a fiber collimator, a quantum sensor, a photomultiplier tube, a data acquisition card, and a computer. The quantum sensor includes a PCB board and a microwave source, a microwave antenna, and a diamond NV color center arranged on the PCB board. The diamond NV color center is located within the excitation range of the microwave antenna. The pulse laser emitted by the semiconductor laser passes through the dichroic mirror and then enters the fiber collimator. The fiber collimator is connected to the diamond NV color center through an optical fiber. The photomultiplier tube is located on the reflected light path of the dichroic mirror. The photomultiplier tube is connected to the computer through a data acquisition card.

2. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The microwave source is connected to the radio frequency source. The microwaves emitted by the microwave source cover the microwave antenna. The microwave source generates microwaves with a frequency scanning accuracy of 1kHz, an output power of 2-8dBm, and a frequency range of 2.0-3.5GHz.

3. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The power of the semiconductor laser is 10 mW, the wavelength is 532 nm, and the modulation mode of the laser pulse is TTL modulation.

4. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: A short-wave dichroic mirror made of fused quartz is used, the cut-off wavelength of which is within the range of 550nm-605nm, and the transmittance and reflectivity of light with a wavelength shorter than 550nm or longer than 605nm are both greater than 90%.

5. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The optical fiber collimator is composed of a single-core multimode optical fiber pigtail with a central wavelength of 780nm and an ultraviolet fused silica lens with a lens diameter of 5mm, a focal length of 5-10mm and a wavelength of 185-2500nm.

6. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The optical fiber adopts a multimode optical fiber with a diameter of 125 μm, and the end of the optical fiber is fixedly connected to the diamond NV color center through epoxy glue.

7. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The radius of the diamond NV color center is between 10nm and 20μm.

8. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The output form of the photomultiplier tube is voltage. The detection range of the photomultiplier tube is 300-850nm weak light, and the sensitivity is greater than 3.4×10 7 V / lm.

9. The insulator leakage current detection device based on quantum weak magnetic field sensing according to claim 1 is characterized in that: The data acquisition card adopts a USB2.0 interface acquisition card with 24-bit accuracy.

10. A detection method using the insulator leakage current detection device based on quantum weak magnetic field sensing according to any one of claims 1 to 9, characterized in that: Here are the steps: S1. Place the quantum sensor near the insulator to be measured, turn on the laser to generate pulsed laser, and the pulsed laser enters the fiber collimator after passing through the dichroic mirror. The fiber collimator converts the incident pulsed laser into collimated light, which is then emitted through the optical fiber to the diamond NV color center. The NV color center undergoes energy level transition under the excitation of 532nm green light and emits red fluorescence. The stimulated red fluorescence is reflected back to the dichroic mirror along the optical fiber and then enters the photomultiplier tube. The photomultiplier tube receives photons and converts them into voltage amplitude output; S2. At the same time, the microwave source on the PCB generates a microwave signal driven by the radio frequency source, and the diamond NV color center is regulated by the microwave antenna. The red fluorescence intensity generated by the excited NV color center changes with the microwave frequency. The microwave frequency is adjusted to quickly sweep in the range of 2.0-3.5 GHz to obtain a spectrum with the horizontal axis being the microwave frequency and the vertical axis being the NV color center fluorescence intensity. S3, using a data acquisition card to quickly collect the voltage signal of the photomultiplier tube, and obtaining a light detection magnetic resonance spectrum through computer processing, wherein the light detection resonance spectrum is a splitting spectrum with two troughs, and the highest light intensity point between the two troughs is defined as the central frequency of the spectrum line; S4. Select the initial splitting spectrum center frequency in the optical detection magnetic resonance spectrum as the zero starting point. When an external magnetic field acts on the color center, the fluorescence spectrum of the NV color center will shift with the magnetic field strength. By calculating the shift value of the center frequency point of the splitting spectrum, the magnitude of the magnetic field strength can be immediately inferred through a linear relationship. S5. The quantum sensor placed near the insulator calculates the magnetic field change at the test position based on the relationship between the magnetic field strength and the zero-field splitting center frequency, and compares whether the magnetic field strength exceeds the safety threshold. If the magnetic field strength exceeds the safety threshold, the leakage current is greater than the safety threshold, indicating that the insulator has deteriorated.

Images