Insulator accumulated dirt detection device and detection method based on piezoelectric effect

Abstract

The invention provides an insulator accumulated dirt detection device and detection method based on a piezoelectric effect, and relates to the technical field of insulator accumulated dirt detection, the insulator accumulated dirt detection device comprises a piezoelectric accumulated dirt sensor, a temperature sensor and a processor; the piezoelectric dirt deposition sensor outputs different frequencies according to the surface quality change of the sensor; the temperature sensor collects the environment temperature to obtain a temperature correction parameter; the processor is connected with the piezoelectric dirt deposition sensor and the temperature sensor, obtains a frequency difference value between the frequency output by the piezoelectric dirt deposition sensor and the initial frequency, corrects the frequency difference value to obtain a corrected frequency difference value, and determines the dirt deposition amount according to the corrected frequency difference value and the area of the piezoelectric dirt deposition sensor; the frequency difference value is corrected, temperature correction is carried out through the temperature correction parameter, and material correction is carried out through a material correction coefficient obtained according to the material of the insulator. According to the invention, high-precision, continuous and dynamic detection of surface dirt on the insulator surface can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of insulator contamination detection, and in particular to an insulator contamination detection device and a detection method based on piezoelectric effect. Background Art

[0002] The contamination on the surface of insulators will lead to the decrease of lightning resistance and insulation level of the line. In power system accidents, the number of flashovers caused by contamination is second only to lightning strikes, but the damage caused by accidents is several times that of lightning strikes. Therefore, accurately detecting the amount of contamination accumulated on insulators and accurately grasping the contamination state on the surface of insulators are of great significance to reducing contamination flashover accidents and ensuring the safe and stable operation of the power grid.

[0003] The traditional manual method for detecting the contamination on the surface of materials such as insulators is to place the insulator sample to be tested in the atmosphere, manually sample the sample surface regularly, and bring the sample back to the laboratory for analysis to obtain the contamination on the surface of the sample to be tested. However, this method takes a long time, obtains little data, and cannot dynamically monitor the contamination on the sample surface.

[0004] For insulator surface contamination detection, the Academic Committee of the International Conference on Large Electric Systems (CIGRE) recommends five contamination detection methods: equivalent salt density method, pollution layer conductivity method, pollution flashover voltage gradient method, pulse counting method and leakage current method. These methods use electrical parameters such as conductivity, voltage gradient, leakage current, etc. as characteristic quantities, which can reflect the overall contamination situation of insulators to a certain extent. However, they generally have problems such as low efficiency, complicated processes and high costs, and cannot accurately and efficiently detect the contamination level of insulators on large-scale lines.

[0005] Considering that the presence of contamination will affect the transmission path and flux of light, many online dynamic monitoring schemes for the contamination status of insulator surfaces based on optical methods have been proposed in the prior art. For example, the Chinese invention patent with publication number CN118758877A discloses a device and method for detecting the contamination level of insulators based on multi-spectral imaging technology, which can quickly and accurately detect the contamination level of insulators based on multi-spectral imaging. However, this patent requires the use of a prediction model to predict the contamination level of insulators, which has high implementation costs, requires a large amount of historical data for training, has a narrow scope of application, and cannot continuously and dynamically monitor the amount of contamination on the surface of insulators. A Chinese invention patent with publication number CN118408922A discloses an online monitoring device and installation method for insulator contamination based on LIBS. The method can realize online measurement of the contamination degree at multiple positions on the surface of the insulator, and the monitoring device is accurately positioned on the transmission tower to ensure the reliability of online monitoring of the contamination degree. However, the solution of the patent is based on a fiber optic LIBS sensor module, and the detection data of the fiber optic sensor is greatly affected by the environment and is easily affected by various factors such as temperature and humidity. The detection accuracy needs to be improved.

[0006] The contamination detection method based on the piezoelectric effect is to dynamically monitor the amount of contamination deposited on the surface of the material based on the principle that changes in the material surface mass cause frequency changes. This method can realize continuous and dynamic monitoring of changes in the amount of contamination on the sample surface, and can dynamically reflect the impact of changes in weather and environmental changes on the amount of contamination on the surface of the insulator, overcoming the deficiency of the existing technology that cannot dynamically and continuously monitor the contamination on the surface of the insulator. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide an insulator contamination detection device and a detection method based on the piezoelectric effect, so as to achieve high-precision continuous dynamic detection of contamination on the surface of the insulator.

[0008] To achieve the above object, according to some embodiments, a first aspect of the present invention provides an insulator contamination detection device based on piezoelectric effect, comprising: a piezoelectric contamination sensor, a temperature sensor, and a processor;

[0009] The piezoelectric dirt accumulation sensor is used to output different frequencies according to the change of the sensor surface quality;

[0010] The temperature sensor is used to collect the ambient temperature and obtain the temperature correction parameter;

[0011] The processor is connected to the piezoelectric contamination sensor and the temperature sensor, and is used to obtain a frequency difference between a frequency output by the piezoelectric contamination sensor and an initial frequency, correct the frequency difference to obtain a corrected frequency difference, and determine the amount of contamination based on the corrected frequency difference and the area of ​​the piezoelectric contamination sensor; wherein the frequency difference is corrected, including temperature correction through a temperature correction parameter, and material correction through a material correction coefficient obtained based on the material of the insulator.

[0012] In a possible implementation manner, the calculation formula for the amount of accumulated dirt is:

[0013] Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S;

[0014] Among them, Δm represents the amount of dirt accumulation, k1 is a constant coefficient, Δf 校 is the frequency difference after correction, K is the material correction coefficient, Δf is the frequency difference between the frequency output by the piezoelectric dirt sensor and the initial frequency, Δf T is the temperature correction parameter, S is the area of ​​the piezoelectric contamination sensor;

[0015] Preferably, the calculation formula for the amount of accumulated dirt is:

[0016] Δm=4.4×10 -5 ×Δf校 / S=4.4×10 -5 ×K×(Δf+Δf T ) / S.

[0017] In a possible implementation, the calculation formula of the temperature correction parameter is:

[0018] Δf T =a1-a2T+a3T 2 ;

[0019] Where T is the ambient temperature, a1, a2, and a3 are fitting coefficients;

[0020] Preferably, the calculation formula of the temperature correction parameter is:

[0021] Δf T =224.64-9.77T+0.058T 2 .

[0022] Preferably, the piezoelectric dirt accumulation sensor is a quartz crystal microbalance sensor.

[0023] In a possible implementation manner, a humidity sensor is further included, and the humidity sensor is connected to the processor and is used to obtain the ambient humidity so that the processor can determine whether the current ambient humidity meets the detection requirements.

[0024] A second aspect of the present invention provides a method for detecting insulator contamination based on a piezoelectric effect, comprising:

[0025] Get the output frequency of the piezoelectric contamination sensor;

[0026] Calculate the frequency difference according to the output frequency of the piezoelectric dirt accumulation sensor and the initial frequency;

[0027] Determine whether the frequency difference exceeds the frequency range of the sensor. If not, correct the frequency difference to obtain the corrected frequency difference.

[0028] The amount of dirt accumulation is obtained according to the pre-stored relationship between the frequency difference and the amount of dirt accumulation.

[0029] In a possible implementation manner, the method for acquiring the frequency range of the sensor includes:

[0030] Collecting samples of accumulated dirt;

[0031] Dispersing the contaminated sample into a solvent to form a dispersion;

[0032] Measure the initial frequency of the piezoelectric contamination sensor;

[0033] Apply the dispersion liquid to the surface of the piezoelectric contamination sensor, and measure the output frequency of the piezoelectric contamination sensor after the dispersion liquid dries;

[0034] Apply the dispersion liquid on the surface of the piezoelectric contamination sensor again, and measure the output frequency of the piezoelectric contamination sensor after drying;

[0035] Compare the two measured output frequencies of the piezoelectric contamination sensor. If the output frequency of the last measurement is greater than or equal to the output frequency of the previous measurement, calculate the sensor frequency range according to the difference between the output frequency of the previous measurement and the initial frequency. If the output frequency of the last measurement is less than the output frequency of the previous measurement, apply the dispersion again and re-measure the output frequency of the piezoelectric contamination sensor.

[0036] Preferably, the contamination sample is contamination that naturally settles outdoors on the surface of the insulator;

[0037] Preferably, the coating method includes spray coating and spin coating, and the solid content in the dispersion coated each time is consistent.

[0038] In a possible implementation, the frequency difference is corrected, including temperature correction and material correction of the frequency difference;

[0039] Preferably, the temperature correction includes obtaining a temperature correction parameter according to the ambient temperature of the piezoelectric contamination sensor; and performing temperature correction on the frequency difference according to the temperature correction parameter.

[0040] Preferably, the material correction includes determining material correction parameters according to the insulator material, and performing material correction on the frequency difference after temperature correction; further, the insulator material includes glass material, ceramic material and polymer material.

[0041] In a possible implementation, it further includes, before calculating the frequency difference, determining whether the ambient humidity exceeds a set threshold value; if not, calculating the frequency difference; if exceeded, stopping detection.

[0042] In a possible implementation manner, the calculation formula for the relationship between the pre-stored frequency difference and the amount of dirt accumulation is:

[0043] Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S;

[0044] Wherein, Δm represents the amount of dirt accumulation, k1 is a constant coefficient, preferably 4.4×10 -5 , Δf 校 is the frequency difference after correction, K is the material correction coefficient, Δf is the frequency difference between the frequency output by the piezoelectric dirt sensor and the initial frequency, Δf Tis the temperature correction parameter, and S is the area of ​​the piezoelectric contamination sensor.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The present invention provides an insulator contamination detection device and a detection method based on the piezoelectric effect, and proposes to detect the amount of contamination on the surface of the insulator based on the piezoelectric effect. The change of the surface quality of the sensor (the amount of contamination) can cause the frequency of the sensor to change. The corresponding relationship between the frequency change and the amount of contamination is obtained in advance, and the amount of contamination on the surface of the sensor can be quickly and accurately calculated according to the difference between the current output frequency of the sensor and the initial frequency, thereby realizing dynamic and continuous monitoring of the amount of contamination, and dynamically reflecting the influence of the changes in the weather and environment on the amount of contamination on the surface of the insulator. By introducing temperature correction, the influence of environmental factors on the detection results is reduced, and the detection accuracy is improved.

[0047] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0049] Figure 1 is a flow chart of the dirt accumulation detection process in the present invention;

[0050] Figure 2 It is a flow chart of the process of acquiring the frequency range of the sensor in the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0052] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0053] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0054] Embodiment 1

[0055] Embodiment 1 of the present invention provides an insulator contamination detection device based on piezoelectric effect, comprising: a piezoelectric contamination sensor, a temperature sensor, and a processor;

[0056] The piezoelectric dirt accumulation sensor is used to output different frequencies according to the change of the sensor surface quality;

[0057] The temperature sensor is used to collect the ambient temperature and obtain the temperature correction parameter;

[0058] The processor is connected to the piezoelectric contamination sensor and the temperature sensor, and is used to obtain a frequency difference between a frequency output by the piezoelectric contamination sensor and an initial frequency, correct the frequency difference to obtain a corrected frequency difference, and determine the amount of contamination based on the corrected frequency difference and the area of ​​the piezoelectric contamination sensor; wherein the frequency difference is corrected, including temperature correction through a temperature correction parameter, and material correction through a material correction coefficient obtained based on the material of the insulator.

[0059] In view of the problems of the prior art in which manual detection of insulator contamination is time-consuming, the amount of data obtained is small, and dynamic monitoring cannot be performed, and the optical method for detecting insulator contamination is complex in algorithm and easily affected by the environment, this embodiment proposes a new contamination detection scheme based on the piezoelectric effect, that is, based on the characteristic that the frequency change is caused by the surface mass of the sensor, the output frequency of the sensor is collected in real time, and the surface contamination amount is calculated, thereby realizing dynamic and continuous monitoring of the surface contamination amount of the insulator.

[0060] The piezoelectric dirt accumulation sensor preferably adopts a quartz crystal microbalance sensor with an initial frequency of 8 MHz. Based on the piezoelectric effect of the quartz crystal, it converts the surface mass change of the quartz crystal electrode into the frequency change of the output electrical signal of the quartz crystal oscillation circuit, and then obtains high-precision data through other auxiliary equipment such as computers.

[0061] Considering that the ambient temperature may affect the frequency of the piezoelectric dirt accumulation sensor, in this embodiment, a temperature sensor is provided next to the piezoelectric dirt accumulation sensor to collect the ambient temperature of the piezoelectric dirt accumulation sensor, and then perform temperature correction according to the collected ambient temperature.

[0062] The temperature correction is to calculate the temperature correction parameter according to the ambient temperature, add the temperature correction parameter to the output frequency of the piezoelectric contamination sensor, and compensate and correct the output frequency of the piezoelectric contamination sensor according to the temperature correction parameter. The calculation formula of the temperature correction parameter is obtained by fitting the experimental data. In this embodiment, a quadratic function is used for fitting, that is:

[0063] Δf T =a1-a2T+a3T2 ;

[0064] Where Δf T is the temperature correction parameter, T is the ambient temperature, and a1, a2, and a3 are fitting coefficients.

[0065] During the experiment, the piezoelectric contamination sensor and the temperature sensor are placed together in a drying oven, and the drying oven is controlled to gradually heat up with a set temperature gradient. After each heating, when the output values ​​of the piezoelectric contamination sensor and the temperature sensor are stable, the output frequency of the piezoelectric contamination sensor and the corresponding ambient temperature at this time are recorded. In order to meet the needs of insulator contamination detection, the experimental temperature range is determined according to the actual temperature range of the insulator environment. For example, the experiment can be carried out in a temperature range of -10°C-50°C, and the output frequency of the piezoelectric contamination sensor at different temperatures within the temperature range is recorded, and then the corresponding relationship between the output frequency of the piezoelectric contamination sensor and the ambient temperature is fitted to compensate for the output frequency of the piezoelectric contamination sensor in the calculation of the amount of contamination. In this embodiment, the calculation formula for the fitted temperature correction parameter is:

[0066] Δf T =224.64-9.77T+0.058T 2 .

[0067] Since the pollution accumulation effects of different surface materials under the same environment are different, it is also necessary to perform material correction on the insulator material. In this embodiment, the surface of the piezoelectric pollution sensor is made of gold, while the commonly used insulator materials are glass, ceramic and polymer materials, among which the polymer material is usually room temperature vulcanized silicone rubber (RTV). Under the same environmental conditions, the pollution accumulation experiment is carried out on the piezoelectric pollution sensor, glass insulator, ceramic insulator and polymer insulator at the same time, and the surface pollution accumulation amount of the piezoelectric pollution sensor, glass insulator, ceramic insulator and polymer insulator within a set time is weighed and measured, so as to obtain the corresponding relationship between the surface pollution conditions of different materials and determine the material correction coefficient. In actual detection, the calculated pollution accumulation amount of the piezoelectric pollution sensor is multiplied by the material correction coefficient of the corresponding insulator material to calculate the pollution accumulation amount of the insulator.

[0068] After a large number of experimental verifications, in this embodiment, the material correction coefficient of glass is 0.9, the material correction coefficient of ceramic is 0.96, and the material correction coefficient of room temperature vulcanized silicone rubber is 2.44.

[0069] The calculation formula for the amount of pollution Δm on the insulator surface is:

[0070] Δm=k1×Δf 校 / S;

[0071] Among them, k1 is a constant coefficient, obtained according to experimental fitting, Δf 校 =K×(Δf+Δf T ) is the corrected frequency difference, S is the area of ​​the piezoelectric fouling sensor. Δf 校 The frequency difference is obtained after temperature correction and material correction. After introducing the temperature correction parameter and material correction coefficient, the calculation formula of the accumulated dirt is further expressed as:

[0072] Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S;

[0073] Where K is the material correction coefficient, Δf T is the temperature correction parameter, and Δf is the frequency difference.

[0074] In this embodiment, after a large amount of experimental data fitting calculation, the constant coefficient k1 is 4.4×10 -5 , then the calculation formula for the amount of accumulated dirt used in this embodiment is:

[0075] Δm=4.4×10 -5 ×Δf 校 / S=4.4×10 -5 ×K×(Δf+Δf T ) / S.

[0076] Considering that the frequency of the piezoelectric dirt accumulation sensor is also affected by the ambient humidity, when the ambient humidity is too high, it will affect the accuracy of the output frequency. In this embodiment, a humidity sensor is also provided for real-time monitoring of the ambient humidity. When the ambient humidity is judged to be ≥99%, it is judged that it is high humidity weather such as rain or heavy fog, and the detection conditions are not met, and the detection is stopped.

[0077] The detection device provided in this embodiment preferably performs pollution detection on reference insulators. In some embodiments, pollution detection can be further implemented on charged insulators. At this time, considering the influence of factors such as electric field and voltage level, there are differences in the degree of pollution accumulation of insulators under different transmission forms (DC transmission, AC transmission) and different voltage levels. Therefore, the charged coefficient k0 can be further introduced into the calculation formula of the pollution amount. The value of k0 is also determined by experiments. At this time, the calculation formula of the pollution amount Δm1 considering the power environment is expressed as:

[0078] Δm1=k0×k1×Δf 校 / S=k0×k1×K×(Δf+Δf T ) / S;

[0079] Among them, k0 is the charging coefficient.

[0080] In some embodiments, the device further includes a communication module, which is connected to the processor and is used to send the calculated amount of accumulated pollution to the host computer via wireless communication to achieve remote real-time detection. The device can be powered by a nearby power grid or solar energy to avoid affecting the operation of the power grid.

[0081] The processor in this embodiment may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor may be implemented in at least one hardware form of DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), and LA (Programmable Logic Array). The processor may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a CPU (Central Processing Unit); the coprocessor is a low-power processor for processing data in the standby state.

[0082] The processor may be further connected to a memory, which may include one or more computer-readable media, which may be non-transitory. The memory may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In some embodiments, the non-transitory computer-readable medium in the memory is used to store at least one computer program, which is used to be executed by the processor to realize the calculation of the amount of accumulated dirt.

[0083] The present embodiment provides an insulator contamination detection device based on the piezoelectric effect, and proposes to detect the amount of contamination on the surface of the insulator based on the piezoelectric effect. The change of the surface quality of the sensor (the amount of contamination) can cause the frequency of the sensor to change. The corresponding relationship between the frequency change and the amount of contamination, that is, the calculation formula of the amount of contamination, is obtained in advance. The amount of contamination on the surface of the sensor can be quickly and accurately calculated according to the difference between the current output frequency of the sensor and the initial frequency, thereby realizing dynamic and continuous monitoring of the amount of contamination, and dynamically reflecting the influence of changes in weather and environment on the amount of contamination on the surface of the insulator.

[0084] Embodiment 2

[0085] This embodiment is based on the insulator contamination detection device based on the piezoelectric effect provided in the first embodiment, and further provides an insulator contamination detection method based on the piezoelectric effect, such as Figure 1-Figure 2 As shown, including:

[0086] S1, obtaining the output frequency f1 of the piezoelectric contamination sensor;

[0087] S2, calculating the frequency difference Δf according to the output frequency f1 and the initial frequency f0 of the piezoelectric dirt accumulation sensor;

[0088] S3, judging whether the frequency difference exceeds the frequency range L of the sensor, and if not, correcting the frequency difference to obtain the corrected frequency difference;

[0089] S4. Obtain the amount of accumulated dirt based on the pre-stored relationship between the frequency difference and the amount of accumulated dirt.

[0090] The method provided in this embodiment is implemented based on an insulator contamination detection device based on piezoelectric effect in Embodiment 1, and the insulator contamination detection device based on piezoelectric effect includes: a piezoelectric contamination sensor, a temperature sensor, and a processor;

[0091] The piezoelectric dirt accumulation sensor is used to output different frequencies according to the change of the sensor surface quality;

[0092] The temperature sensor is used to collect the ambient temperature and obtain the temperature correction parameter;

[0093] The processor is connected to the piezoelectric contamination sensor and the temperature sensor, and is used to obtain a frequency difference between a frequency output by the piezoelectric contamination sensor and an initial frequency, correct the frequency difference to obtain a corrected frequency difference, and determine the amount of contamination based on the corrected frequency difference and the area of ​​the piezoelectric contamination sensor; wherein the frequency difference is corrected, including temperature correction through a temperature correction parameter, and material correction through a material correction coefficient obtained based on the material of the insulator.

[0094] Considering that the frequency of the piezoelectric dirt accumulation sensor is also affected by the ambient humidity, when the ambient humidity is too high, it will affect the accuracy of the output frequency. In some embodiments, a humidity sensor is also provided for real-time monitoring of the ambient humidity. When it is determined that the ambient humidity does not meet the detection conditions, the detection is stopped. At this time, in step S1, when the output frequency of the piezoelectric dirt accumulation sensor is obtained, the ambient humidity H of the environment in which the piezoelectric dirt accumulation sensor is located is also obtained at the same time. Before calculating the frequency difference, first determine whether the ambient humidity exceeds the set threshold (the threshold is set to 99% in this embodiment, that is, determine whether the ambient humidity is greater than or equal to 99%). If it does not exceed, calculate the frequency difference. If it exceeds, stop the detection.

[0095] The initial frequency f0 of the piezoelectric dirt accumulation sensor is the output frequency of the piezoelectric dirt accumulation sensor when there is no dirt accumulation. In this embodiment, the piezoelectric dirt accumulation sensor uses a quartz crystal microbalance sensor with an initial frequency of 8 MHz.

[0096] In some embodiments, in step S3, the method for acquiring the sensor frequency range of the piezoelectric contamination sensor includes:

[0097] S301, collecting pollutant samples;

[0098] S302, dispersing the contaminated sample into a solvent to form a dispersion;

[0099] S303, measuring the initial frequency f0 of the piezoelectric contamination sensor;

[0100] S304, applying the dispersion liquid to the surface of the piezoelectric dirt accumulation sensor, and measuring the output frequency f11 of the piezoelectric dirt accumulation sensor after the dispersion liquid is dried;

[0101] S305, repeating step S304 once, that is, applying the dispersion liquid on the surface of the piezoelectric dirt accumulation sensor again, and measuring the output frequency f12 of the piezoelectric dirt accumulation sensor after drying;

[0102] S306, compare the output frequency f12 of the piezoelectric dirt sensor in step S305 with the output frequency f11 of the piezoelectric dirt sensor measured in step S304. If the output frequency f12 of the piezoelectric dirt sensor in step S305 is greater than or equal to the output frequency f11 of the piezoelectric dirt sensor measured in step S304, obtain the sensor frequency range L according to the difference between the output frequency f11 of step S304 and the initial frequency f0; if the output frequency f12 of the piezoelectric dirt sensor in step S305 is less than the output frequency f11 of the piezoelectric dirt sensor measured in step S304, repeat step S305, apply the dispersion again and re-measure the output frequency f13 of the piezoelectric dirt sensor, and compare the output frequency f13 measured this time with the output frequency f12 measured last time. For ease of expression, as Figure 2 As shown, assuming that in the nth measurement, the output frequency of this measurement is f1n, and the output frequency of the previous measurement is f1(n-1), calculate the difference Δf1 between f1n and f1(n-1), if Δf1<0, apply the dispersion again, if Δf1≥0, calculate the sensor frequency range L based on the difference between the output frequency f1(n-1) of the previous measurement and the initial frequency f0.

[0103] In step S301, the pollution sample is pollution that naturally settles outdoors, and preferably, pollution that naturally settles on the surface of an insulator.

[0104] In step S302, the solvent is selected from volatile organic solvents, preferably ethanol, acetone or a mixture of the two. The solids (i.e., dirt) in the formed dispersion should be as evenly dispersed as possible, and the solid concentration should not be too low or too high. If the concentration is too low, the dispersion will not be easy to dry after being applied to the surface of the piezoelectric dirt sensor, and there will be problems of uneven drying during drying, which will cause the solids in the dispersion to aggregate, thereby affecting the uniformity of dirt accumulation on the surface of the piezoelectric dirt sensor; and if the concentration is too high, there is a risk of clogging the nozzle when applying the dispersion. In this embodiment, it is preferred to disperse 1.0 mg of the dirt sample in 10 mL of solvent to form a dispersion, and the solids in the dispersion applied each time do not exceed 150 μg.

[0105] In step S304, the coating method includes spraying and spin coating, and the solid content in the dispersion applied each time is controlled to be consistent during coating. Since the contaminated sample has been evenly dispersed in the solvent in step S302, it is sufficient to control the quality of the dispersion applied each time during coating. The dispersion can be dried by natural air drying or heating and drying. When heating and drying, it is preferred to set the heating and drying temperature not to exceed 40°C, and use a temperature slightly higher than room temperature for heating and drying to simulate the natural air drying conditions in the outdoor environment, so as to avoid the volatilization of high-temperature volatile substances that may exist in the contamination due to excessively high temperature, thereby causing errors.

[0106] In step S3, the frequency difference is corrected, including temperature correction and material correction. The temperature correction includes obtaining a temperature correction parameter according to the ambient temperature of the piezoelectric contamination sensor; and performing temperature correction on the frequency difference according to the temperature correction parameter.

[0107] Considering that the ambient temperature may affect the frequency of the piezoelectric dirt accumulation sensor, in this embodiment, a temperature sensor is provided next to the piezoelectric dirt accumulation sensor to collect the ambient temperature of the piezoelectric dirt accumulation sensor, and then perform temperature correction according to the collected ambient temperature.

[0108] The temperature correction is to calculate the temperature correction parameter according to the ambient temperature, add the temperature correction parameter to the output frequency of the piezoelectric contamination sensor, and compensate and correct the output frequency of the piezoelectric contamination sensor according to the temperature correction parameter. The calculation formula of the temperature correction parameter is obtained by fitting the experimental data. In this embodiment, a quadratic function is used for fitting, that is:

[0109] Δf T =a1-a2T+a3T 2 ;

[0110] Where Δf T is the temperature correction parameter, T is the ambient temperature, and a1, a2, and a3 are fitting coefficients.

[0111] During the experiment, the piezoelectric contamination sensor and the temperature sensor are placed together in a drying oven, and the drying oven is controlled to gradually heat up with a set temperature gradient. After each heating, when the output values ​​of the piezoelectric contamination sensor and the temperature sensor are stable, the output frequency of the piezoelectric contamination sensor and the corresponding ambient temperature at this time are recorded. In order to meet the needs of insulator contamination detection, the experimental temperature range is determined according to the actual temperature range of the insulator environment. For example, the experiment can be carried out in a temperature range of -10°C-50°C, and the output frequency of the piezoelectric contamination sensor at different temperatures within the temperature range is recorded, and then the corresponding relationship between the output frequency of the piezoelectric contamination sensor and the ambient temperature is fitted to compensate for the output frequency of the piezoelectric contamination sensor in the calculation of the amount of contamination. In this embodiment, the calculation formula for the fitted temperature correction parameter is:

[0112] Δf T =224.64-9.77T+0.058T 2 .

[0113] Material correction includes determining material correction parameters according to the insulator material and performing material correction on the frequency difference after temperature correction.

[0114] Since the pollution accumulation effects of different surface materials under the same conditions are different, it is also necessary to perform material correction on the insulator material. In this embodiment, the surface of the piezoelectric pollution accumulation sensor is made of gold, while the commonly used insulator materials are glass, ceramic and polymer materials, among which the polymer material is usually room temperature vulcanized silicone rubber (RTV). Under the same environmental conditions, the pollution accumulation experiment is carried out on the piezoelectric pollution accumulation sensor, glass insulator, ceramic insulator and polymer insulator at the same time, and the surface pollution accumulation amount of the piezoelectric pollution accumulation sensor, glass insulator, ceramic insulator and polymer insulator within a set time is weighed and measured, so as to obtain the corresponding relationship between the surface pollution conditions of different materials and determine the material correction coefficient. In actual detection, the calculated pollution accumulation amount of the piezoelectric pollution accumulation sensor is multiplied by the material correction coefficient of the corresponding insulator material to calculate the pollution accumulation amount of the insulator.

[0115] After a large number of experimental verifications, in this embodiment, the material correction coefficient of glass is 0.9, the material correction coefficient of ceramic is 0.96, and the material correction coefficient of room temperature vulcanized silicone rubber is 2.44.

[0116] In step S4, the relationship between the pre-stored frequency difference and the amount of dirt accumulation is the calculation formula for the amount of dirt accumulation. The calculation formula for the amount of dirt accumulation Δm is:

[0117] Δm=k1×Δf 校 / S;

[0118] Among them, k1 is a constant coefficient, obtained according to experimental fitting, Δf 校 is the corrected frequency difference, S is the area of ​​the piezoelectric fouling sensor, and is the response area of ​​the sensor. 校 The frequency difference is obtained after temperature correction and material correction. After introducing the temperature correction parameter and material correction coefficient, the calculation formula of the accumulated dirt is further expressed as:

[0119] Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S;

[0120] Where K is the material correction coefficient, Δf T is the temperature correction parameter, and Δf is the frequency difference.

[0121] This embodiment further provides an insulator contamination detection method based on the piezoelectric effect. Through the output frequency of the piezoelectric contamination sensor, the current ambient temperature and ambient humidity, combined with the pre-stored initial frequency of the piezoelectric contamination sensor, the material correction coefficient of the insulator to be tested, and the relationship between the frequency difference and the contamination amount, the amount of contamination on the surface of the insulator can be quickly and accurately calculated, thereby realizing dynamic detection of insulator contamination.

[0122] Embodiment 3

[0123] A sample of dirt accumulated on the surface of an in-service glass insulator of a transmission line X1 was collected, 1.0 mg of the sample was weighed and dispersed in 10 mL of ethanol to obtain a dispersion A1.

[0124] The measured initial frequency f0 of the piezoelectric dirt sensor is 7985362Hz.

[0125] Spray the dispersion A1 on the surface of the piezoelectric dirt sensor, and measure the frequency f11 of the piezoelectric dirt sensor after dirt accumulation after natural air drying to be 7983424Hz. Spray the dispersion A1 on the surface of the piezoelectric dirt sensor again, and measure the frequency f12 of the piezoelectric dirt sensor after dirt accumulation after drying to be 7980738Hz. Calculate the difference between f12 and f11 Δf11=7980738-7983424=-2686Hz<0, and repeat the spraying of the dispersion, drying, and measuring the frequency of the piezoelectric sensor. When spraying for the 16th time, the frequency f116 of the piezoelectric dirt sensor after drying is 7957741Hz. When spraying for the 17th time, the frequency f117 of the piezoelectric dirt sensor after drying is 7961419Hz. The difference between f117 and f116 is calculated as Δf16=7961419-7957741=3678Hz>0, and the frequency range of the sensor is obtained as L=f0-f116=7985362-7957741=27621Hz.

[0126] The detection device equipped with a piezoelectric contamination sensor was placed near the glass insulator of the transmission line. Before placement, the initial frequency f01 of the piezoelectric contamination sensor was measured to be 7974938 Hz, and the surface area of ​​the piezoelectric sensor was 4.9 cm 2 . Collect the data of the piezoelectric dirt sensor, the ambient temperature, the ambient humidity and the frequency of the piezoelectric dirt sensor after dirt accumulation every 60 minutes. After 5 months of placement, measure the ambient humidity and find that the ambient humidity is 63% < 99%, and continue to test. Measure the frequency f1 of the piezoelectric dirt sensor after dirt accumulation to be 7960902Hz, and the ambient temperature T is 24.5℃. Calculate the frequency difference of the piezoelectric dirt sensor before and after dirt accumulation Δf = f01-f1 =

[0127] 7974938-7960902=14036Hz<27621Hz, which does not exceed the frequency range of the sensor. Substitute the temperature 24.5℃ and the material correction coefficient K=0.9 of the glass material to correct Δf.

[0128] Substitute the temperature correction parameters into the calculation formula:

[0129] Δf T =224.64-9.77T+0.058T 2 ;

[0130] Get Δf T is 20.09Hz;

[0131] Substitute Δf 校 =K×(Δf+Δf T ), and we get Δf 校 is 12650.48Hz;

[0132] Further substitute into the calculation formula of the accumulated pollution:

[0133] Δm=4.4×10 -5 ×Δf 校 / S=4.4×10 -5 ×K×(Δf+Δf T ) / S;

[0134] The calculated surface contamination of the insulator is 0.113 mg / cm 2 .

[0135] Embodiment 4

[0136] This embodiment is a comparative example of the third embodiment.

[0137] The surface dirt samples of the glass insulators of the transmission line X1 placed at the same time were collected by wiping method. After filtering and drying the solution, the mass of the dirt on the surface of the glass insulator was weighed to 105.34 mg. According to the surface area of ​​the insulator of this model, 825 cm 2 The calculated surface contamination of the glass insulator is 0.128 mg / cm 2 Therefore, it can be obtained that the error between the detection result of the insulator contamination amount by the method provided by the present invention and the actual measured value is (0.128-0.113) / 0.128*100%=11.7%, which verifies the effectiveness of the method provided by the present invention.

[0138] Embodiment 5

[0139] Different from the third embodiment, in this embodiment, samples of surface contamination on in-service ceramic insulators of a certain transmission line X2 were collected, dispersed with acetone, and the dispersion A2 was sprayed on the surface of the piezoelectric contamination sensor, and then dried in an oven, and the oven temperature was set to 40°C. The initial frequency of the piezoelectric contamination sensor was measured to be 7983733Hz. When sprayed for the 16th time, the frequency of the piezoelectric contamination sensor after contamination after drying was 7962749Hz. When sprayed for the 17th time, the frequency of the piezoelectric contamination sensor after contamination after drying was 7963128Hz. The difference between the two values ​​Δf16=7963128-7962749=379Hz>0 is calculated, and the frequency range of the sensor is L=7983733-7962749=20984Hz.

[0140] The detection device equipped with a piezoelectric pollution sensor was placed near the ceramic insulator and the room temperature vulcanized silicone rubber composite insulator of the transmission line. Before placement, the initial frequency f0 of the piezoelectric pollution sensor was measured to be 7987426Hz, and the surface area of ​​the piezoelectric sensor was 4.9cm 2 . The piezoelectric dirt sensor data, ambient temperature, ambient humidity and the frequency of the piezoelectric dirt sensor after dirt accumulation are collected every 60 minutes. After 5 months of placement, the ambient humidity H is measured and the ambient humidity is 30% < 99%, so the detection can continue. The frequency f1 of the piezoelectric dirt sensor after dirt accumulation is measured to be 7970884Hz, and the ambient temperature T is 20.2℃. The frequency difference Δf of the piezoelectric dirt sensor before and after dirt accumulation is calculated to be 16542Hz < 20984Hz, which does not exceed the sensor frequency range.

[0141] Substituting the temperature 20.2℃ and the ceramic material coefficient K=0.96 to correct Δf, we get Δf T is 50.95Hz, Δf 校 The frequency is 15929.23 Hz, and the amount of dirt on the surface of the ceramic insulator is calculated to be 0.143 mg / cm 2 .

[0142] Substituting the temperature of 20.2°C and the material coefficient of room temperature vulcanized silicone rubber K = 2.44 to correct Δf, we get Δf T is 50.95Hz, Δf 校 The frequency is 40486.80Hz, and the amount of dirt on the surface of the ceramic insulator is calculated to be 0.364mg / cm 2 .

[0143] Embodiment 6

[0144] This embodiment is a comparative example of the fifth embodiment.

[0145] The wiping method was used to collect surface dirt samples of X2 ceramic insulators and room temperature vulcanized silicone rubber insulators of the transmission line placed at the same time.

[0146] After filtering and drying the solution, the surface dirt mass of the ceramic insulator was weighed to 192.59 mg. According to the data obtained, the surface area of ​​the insulator of this model is 1480 cm 2 The calculated surface contamination of the glass insulator is 0.130 mg / cm 2 Compared with the fifth embodiment, the error between the detection result of the amount of dirt deposited on the ceramic insulators in the present embodiment and the actual measured value is 10.0%.

[0147] After the solution was filtered and dried, the surface dirt mass of the room temperature vulcanized silicone rubber composite insulator was weighed to 601.47 mg. According to the surface area of ​​this model of insulator, it was found to be 1530 cm 2 The surface dirt accumulation of room temperature vulcanized silicone rubber composite insulator is calculated to be 0.393 mg / cm 2 Compared with the fifth embodiment, the error between the detection result of the amount of dirt accumulation of the room temperature vulcanized silicone rubber composite insulator in the present embodiment and the actual measured value is -7.4%.

[0148] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An insulator contamination detection device based on piezoelectric effect, characterized in that: include: Piezoelectric contamination sensor, temperature sensor, processor; The piezoelectric dirt accumulation sensor is used to output different frequencies according to the change of the sensor surface quality; The temperature sensor is used to collect the ambient temperature and obtain the temperature correction parameter; The processor is connected to the piezoelectric contamination sensor and the temperature sensor, and is used to obtain a frequency difference between a frequency output by the piezoelectric contamination sensor and an initial frequency, correct the frequency difference to obtain a corrected frequency difference, and determine the amount of contamination based on the corrected frequency difference and the area of ​​the piezoelectric contamination sensor; wherein the frequency difference is corrected, including temperature correction through a temperature correction parameter, and material correction through a material correction coefficient obtained based on the material of the insulator.

2. The insulator contamination detection device based on piezoelectric effect according to claim 1, characterized in that: The calculation formula of the accumulated dirt is: Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S; Among them, Δm represents the amount of dirt accumulation, k1 is a constant coefficient, Δf 校 is the frequency difference after correction, K is the material correction coefficient, Δf is the frequency difference between the frequency output by the piezoelectric dirt sensor and the initial frequency, Δf T is the temperature correction parameter, S is the area of ​​the piezoelectric contamination sensor; Preferably, the calculation formula for the amount of accumulated dirt is: Δm=4.4×10 -5 ×Δf 校 / S=4.4×10 -5 ×K×(Δf+Δf T ) / S。 3. The insulator contamination detection device based on piezoelectric effect as claimed in claim 2, characterized in that: The calculation formula of the temperature correction parameter is: Δf T =a1-a2T+a3T 2 ; Where T is the ambient temperature, a1, a2, and a3 are fitting coefficients; Preferably, the calculation formula of the temperature correction parameter is: Δf T =224.64-9.77T+0.058T 2 。 4. The insulator contamination detection device based on piezoelectric effect as claimed in claim 1, characterized in that: The piezoelectric dirt accumulation sensor is a quartz crystal microbalance sensor.

5. The insulator contamination detection device based on piezoelectric effect according to claim 1, characterized in that: It also includes a humidity sensor, which is connected to the processor and is used to obtain the ambient humidity so that the processor can determine whether the current ambient humidity meets the detection requirements.

6. A method for detecting insulator contamination based on piezoelectric effect, characterized in that: include: Get the output frequency of the piezoelectric contamination sensor; Calculate the frequency difference according to the output frequency of the piezoelectric dirt accumulation sensor and the initial frequency; Determine whether the frequency difference exceeds the frequency range of the sensor. If not, correct the frequency difference to obtain the corrected frequency difference. The amount of dirt accumulation is obtained according to the pre-stored relationship between the frequency difference and the amount of dirt accumulation.

7. The insulator contamination detection method based on piezoelectric effect as claimed in claim 6, characterized in that: The method for acquiring the frequency range of the sensor includes: Collecting samples of accumulated dirt; Dispersing the contaminated sample into a solvent to form a dispersion; Measure the initial frequency of the piezoelectric contamination sensor; Apply the dispersion liquid to the surface of the piezoelectric contamination sensor, and measure the output frequency of the piezoelectric contamination sensor after the dispersion liquid dries; Apply the dispersion liquid on the surface of the piezoelectric contamination sensor again, and measure the output frequency of the piezoelectric contamination sensor after drying; Compare the two measured output frequencies of the piezoelectric contamination sensor. If the output frequency of the last measurement is greater than or equal to the output frequency of the previous measurement, calculate the sensor frequency range according to the difference between the output frequency of the previous measurement and the initial frequency. If the output frequency of the last measurement is less than the output frequency of the previous measurement, apply the dispersion again and re-measure the output frequency of the piezoelectric contamination sensor. Preferably, the contamination sample is contamination that naturally settles outdoors on the surface of the insulator; Preferably, the coating method includes spray coating and spin coating, and the solid content in the dispersion coated each time is consistent.

8. The insulator contamination detection method based on piezoelectric effect as claimed in claim 6, characterized in that: Correct the frequency difference, including temperature correction and material correction; Preferably, the temperature correction includes obtaining a temperature correction parameter according to the ambient temperature of the piezoelectric contamination sensor; and performing temperature correction on the frequency difference according to the temperature correction parameter; Preferably, the material correction includes determining material correction parameters according to the insulator material, and performing material correction on the frequency difference after temperature correction; further, the insulator material includes glass material, ceramic material and polymer material.

9. The method for detecting insulator contamination based on piezoelectric effect according to claim 6, characterized in that: It also includes, before calculating the frequency difference, judging whether the ambient humidity exceeds a set threshold value, if not, calculating the frequency difference value, if exceeded, stopping the detection.

10. The insulator contamination detection method based on piezoelectric effect according to claim 6, characterized in that: The calculation formula for the relationship between the pre-stored frequency difference and the amount of accumulated dirt is: Δm=k1×Δf 校 / S=k1×K×(Δf+Δf T ) / S; Wherein, Δm represents the amount of dirt accumulation, k1 is a constant coefficient, preferably 4.4×10 -5 , Δf 校 is the frequency difference after correction, K is the material correction coefficient, Δf is the frequency difference between the frequency output by the piezoelectric dirt sensor and the initial frequency, Δf T is the temperature correction parameter, and S is the area of ​​the piezoelectric contamination sensor.

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