Method and system for evaluating pollution resistance of insulator

Abstract

The invention provides a method and system for evaluating the pollution resistance of an insulator, and belongs to the technical field of monitoring of an insulator of a power system, and the method comprises the steps: carrying out the pulse irradiation of the surface of the insulator through a high-power halogen light source; continuously monitoring the surface of the insulator through a multispectral imaging device; calculating the water content attenuation rate according to the monitoring data obtained by the multispectral imaging equipment; performing grading evaluation on the surface pollution resistance of the insulator according to the calculated water content attenuation rate; and performing pseudo-colorization treatment according to an evaluation result to obtain a visual result of the sewage-resistant level of the surface of the insulator. According to the method, the surface of the insulator is continuously monitored through the multispectral imaging technology, reflectivity data can be rapidly obtained, the water content attenuation rate is obtained through an accurate calculation method, and therefore the pollution resistance of the insulator is accurately evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of monitoring insulators in a power system, and in particular to a method and system for evaluating the pollution resistance of an insulator. Background Art

[0002] In the power system, the pollution resistance level of the insulator is crucial to its performance. The pollution on the surface of the insulator formed under the influence of the long-term external environment will lead to the decline of the lightning resistance and insulation level of the line. In order to achieve effective evaluation of the pollution status of the insulator, the Academic Committee of the International Conference on Large Electric Systems (CIGRE) recommended pollution detection methods such as equivalent salt density method, pollution layer conductivity method, pollution flash voltage gradient method, pulse counting method and leakage current method. These traditional detection methods mainly use electrical parameters such as conductivity, voltage gradient, leakage current, etc. as characteristic quantities to reflect the overall pollution situation of the insulator, but they generally have problems such as low efficiency, complicated processes, and high costs. It is impossible to accurately and efficiently detect the pollution level of insulators on large-scale lines. In addition, traditional methods cannot reflect the distribution of pollution on the surface of the insulator, and it is difficult to reflect the pollution resistance of the surface of the insulator through the pollution state.

[0003] In recent years, various optical imaging technologies have been applied to the detection of the contamination status of line insulators, among which solar-blind ultraviolet discharge imaging and infrared thermal imaging are the most representative. They have the advantages of non-contact measurement and online detection, and can effectively detect abnormal corona and heating problems of external insulation. However, under normal atmospheric conditions, even if the insulator is seriously contaminated, it may not necessarily cause a significant increase in surface leakage current or surface electric field distortion, and there is a lack of conditions for insulator heating and abnormal corona. Therefore, infrared imaging and ultraviolet solar-blind imaging are not sensitive to insulator contamination. In addition, sparse spectral insulator contamination imaging is currently mainly used to improve the contrast of the contaminated area or perform spectral analysis of the contamination components, and there is no evaluation method for the surface contamination resistance of the insulator.

[0004] "Detection of Insulator Contamination and Water Content Based on Hyperspectral Technology", Ma Huan, Guo Yujun, Zhang Xueqin, et al. This prior art uses hyperspectral technology to obtain real-time spectral information of the contamination state of the insulator surface, and then quantitatively detects the contamination and water content. First, a hyperspectral imager is used to collect spectra of moist contaminated samples, and the collected spectral lines are preprocessed using black and white correction and multivariate scattering correction to remove noise, scattering and other interference. Then, the continuous projection algorithm data is used for dimensionality reduction to extract the characteristic bands of the spectrum lines. Finally, a back propagation neural network prediction model is established for the full band and the characteristic band, and the root mean square error of the prediction set is 0.1101 and 0.0768 respectively. This prior art uses hyperspectral technology and BP neural network algorithm to detect the contamination and water content of insulators. However, hyperspectral equipment requires static shooting, and has high requirements for shooting stability and shooting time. For the actual insulator contamination and water content detection and calibration, the water content has different dynamic change characteristics under different atmospheric humidity. It is difficult to achieve dynamic shooting and evaluation through drones or handheld methods using hyperspectral imaging technology. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method and system for evaluating the pollution resistance of an insulator.

[0006] The present invention adopts the following technical solution.

[0007] A first aspect of the present invention provides a method for evaluating the surface pollution resistance of an insulator, comprising the following steps:

[0008] Use a high-power halogen light source to pulse irradiate the insulator surface;

[0009] Continuous monitoring of the insulator surface using multi-spectral imaging equipment;

[0010] The water content attenuation rate D is calculated based on the monitoring data obtained by the multi-spectral imaging equipment;

[0011] The pollution resistance of the insulator surface is graded and evaluated according to the calculated moisture content attenuation rate D;

[0012] Pseudo-color processing is performed based on the evaluation results to obtain the visualization results of the pollution resistance level of the insulator surface.

[0013] Optionally, the light pulse wavelength range of the high-power halogen light source covers 900nm to 2.5μm, the peak power is not less than 1500W, and the total energy in the irradiated area is not less than 15J.

[0014] Optionally, the monitoring data obtained by the multi-spectral imaging device includes the insulator surface at a characteristic wavelength λ obtained by continuous shooting within a period of time t. i The reflectivity R under.

[0015] Optionally, the water content decay rate D is obtained by exponential fitting, and the specific fitting function form is:

[0016] MC(t)=MC0exp(C-Dt)

[0017] Among them, MC(t) is the water content at time t after light source irradiation, MC0 is the relative reflectivity at the initial moment after halogen light source irradiation, C is the fitting delay, t represents time, and D is the water content attenuation rate.

[0018] Optionally, the calculation formula of the water content MC is:

[0019]

[0020] Among them, A is -0.7123; B is 2.889, A and B are empirical parameters; R′ is the relative spectral reflectance.

[0021] Optionally, the relative spectral reflectance R′ is i The root mean square of the ratio of the reflectivity R of the standard gray plate to the reflectivity R0 is calculated as follows:

[0022]

[0023] Where N is the number of units in the characteristic wavelength sequence, λ i is the characteristic wavelength.

[0024] Optionally, the characteristic wavelength λ i Including 458.5nm, 543.2nm, 671.5nm, 750.5nm, 915.3nm and 997.9nm.

[0025] Optionally, the evaluation standard for the stain resistance of the insulator surface is:

[0026] When D∈(0,a1], the stain resistance level is level I, indicating that the stain resistance level is poor;

[0027] When D∈(a1,a2], the stain resistance level is level II, indicating that the stain resistance level has decreased significantly;

[0028] When D∈(a2,a3], the stain resistance level is level III, indicating that the stain resistance level is slightly decreased;

[0029] When D∈(a3,a4], the stain resistance level is IV, indicating a good stain resistance level.

[0030] Optionally, for the vulcanized silicone rubber composite insulator, the values ​​of a1 to a4 include:

[0031] a1=3.5, a2=6, a3=9.5, a4=13;

[0032] For ceramic insulators, the values ​​of a1 to a4 include:

[0033] a1=2.5, a2=4.5, a3=7, a4=10.

[0034] A second aspect of the present invention provides a system for evaluating the surface pollution resistance of an insulator. Based on the method for evaluating the surface pollution resistance of an insulator described in the first aspect of the present invention, the system comprises:

[0035] A high-power halogen light source, a multi-spectral imaging device, a moisture attenuation rate calculation module, a grading evaluation module and a visualization module, wherein the high-power halogen light source is used to perform pulse irradiation on the insulator surface, the multi-spectral imaging device is used to continuously monitor the insulator surface, the moisture attenuation rate calculation module is used to calculate the moisture attenuation rate based on the monitoring data, the grading evaluation module is used to perform graded evaluation on the pollution resistance of the insulator surface based on the moisture attenuation rate, and the visualization module is used to perform pseudo-color processing based on the evaluation results and output the visualization results of the pollution resistance level of the insulator surface.

[0036] Compared with the prior art, the beneficial effects of the present invention include at least: the present invention provides a method for evaluating the surface pollution resistance of an insulator based on multispectral imaging technology, which has the following advantages over the prior art:

[0037] 1. High efficiency and accuracy: The present invention continuously monitors the surface of the insulator through multi-spectral imaging technology, can quickly obtain reflectivity data, and obtain the moisture content attenuation rate through precise calculation methods, thereby achieving accurate evaluation of the pollution resistance of the insulator.

[0038] 2. Real-time dynamic monitoring: Different from the traditional static detection method, the present invention can realize real-time dynamic monitoring of the insulator surface and provide more continuous and comprehensive data support.

[0039] 3. Visual evaluation: The present invention uses pseudo-color processing to intuitively display the anti-fouling ability evaluation results, making the evaluation results more intuitive and easy to understand, and facilitating operation and maintenance personnel to make decisions quickly.

[0040] 4. Easy operation: The present invention simplifies the operation process, reduces the dependence on professional equipment, makes the evaluation process simpler, and reduces the skill requirements for professionals.

[0041] 5. Cost-effectiveness: Compared with traditional methods, this invention reduces equipment investment and labor costs, and improves the economic efficiency of the assessment.

[0042] 6. Strong environmental adaptability: The present invention is not limited by general atmospheric conditions and can sensitively reflect the contamination state of the insulator even when no significant increase in surface leakage current or surface electric field distortion is caused on the surface of the insulator.

[0043] 7. Comprehensive evaluation: The present invention not only evaluates the overall contamination condition of the insulator, but also reflects the surface contamination distribution characteristics, comprehensively evaluates the impact on the flashover voltage, and provides a more comprehensive evaluation result. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic diagram of a visualization result (RH=55%) of the stain resistance evaluation and grading provided in accordance with an embodiment of the present invention;

[0045] Figure 2 It is a schematic diagram of a method flow provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0047] The patent applicant's previous research shows that the water content of dirt on the surface of the insulator is closely related to its dirt resistance (such as hydrophobicity). When the hydrophobicity of the insulator surface decreases or powdering occurs, the drying ability of the dirt layer under wet conditions will also decrease significantly, and the dehydration rate under the same conditions is positively correlated with the hydrophobicity of the insulator surface. To this end, the present invention aims to use multispectral imaging technology to calculate the water content per unit area by the spectral reflectivity of a specific band, and evaluate the dirt resistance of the insulator surface through the change in water content after active heat source irradiation, so as to achieve non-contact, continuous visual dynamic monitoring. Reflection spectrum imaging technology can select several characteristic bands of insulators to achieve wide-band sparse spectrum imaging, and give full play to the advantages of sparse spectrum cameras with small size, fast imaging speed and high image spatial resolution without losing the accuracy of dirt status assessment.

[0048] The present invention provides a method for continuously monitoring the moisture content on the surface of an insulator by combining active heat source irradiation with multispectral imaging technology, and evaluating its pollution resistance through an exponential model. The method performs a visual graded evaluation of the pollution resistance of the insulator surface by calculating the moisture content attenuation rate.

[0049] The present invention provides a method for evaluating the surface pollution resistance of an insulator in embodiment 1, such as Figure 2As shown, the method comprises the following steps:

[0050] Step 1: Use a high-power halogen light source to pulse irradiate the insulator surface;

[0051] In a further preferred but non-limiting embodiment, the light pulse wavelength range of the high-power halogen light source covers 900nm to 2.5μm, the peak power is not less than 1500W, and the total energy in the irradiated area is not less than 15J;

[0052] Furthermore, an effective prerequisite for carrying out radiation and spectral image monitoring is that the relative humidity of the atmosphere is not less than 40%.

[0053] Step 2: Continuously monitor the insulator surface using multi-spectral imaging equipment;

[0054] In a further preferred but non-limiting embodiment, the monitoring data includes:

[0055] The pixel gray value matrix of the multispectral image obtained by the multispectral imaging device through continuous shooting of a fixed object within a period of time t can be converted into a pixel position reflectivity matrix.

[0056] Step 3: Calculate the water content decay rate based on the monitoring data;

[0057] In a further preferred but non-limiting embodiment, the water content decay rate D is obtained by exponential fitting, and the specific fitting function form is:

[0058] MC(t)=MC0exp(C-Dt)

[0059] Among them, MC(t) is the water content at time t after light source irradiation, MC0 is the relative reflectivity at the initial moment after halogen light source irradiation, C is the fitting delay, t represents time, and D is the derivative of the time constant, that is, the water content decay rate.

[0060] In a further preferred but non-limiting embodiment, the calculation formula of the water content MC is:

[0061]

[0062] Wherein, A is -0.7123; B is 2.889, A and B are empirical parameters, and their values ​​are empirical values ​​determined by experiments given by the present invention, which are preferred values; R' is the relative spectral reflectance. In a further preferred but non-limiting embodiment, the relative spectral reflectance R' is the root mean square of the ratio of the reflectance R at a specific wavelength (λi) to the reflectance R0 of the standard gray plate, calculated as follows:

[0063]

[0064] Where N is the number of units in the characteristic wavelength sequence, λ i is the characteristic wavelength, preferably,

[0065] λ i =458.5nm, 543.2nm, 671.5nm, 750.5nm, 915.3nm, 997.9nm.

[0066] Step 4: grade and evaluate the pollution resistance of the insulator surface according to the moisture content attenuation rate calculated in step 3;

[0067] In a further preferred but non-limiting embodiment, the evaluation standard for the pollution resistance trace on the surface of the insulator is: when D∈(0,a1], the pollution resistance level is level I, indicating that the pollution resistance level is poor;

[0068] When D∈(a1,a2], the stain resistance level is level II, indicating that the stain resistance level has decreased significantly;

[0069] When D∈(a2,a3], the stain resistance level is level III, indicating that the stain resistance level is slightly decreased;

[0070] When D∈(a3,a4], the stain resistance level is IV, indicating a good stain resistance level;

[0071] Among them, for vulcanized silicone rubber composite insulators and ceramic insulators, the preferred values ​​of a1 to a4 are:

[0072] Insulator Type <![CDATA[a1]]> <![CDATA[a2]]> <![CDATA[a3]]> <![CDATA[a4 <!-- 4 -->]]> Composite insulator 3.5 6 9.5 13 Ceramic Insulators 2.5 4.5 7 10

[0073] Step 5: Perform pseudo-color processing based on the evaluation results to obtain a visualization result of the pollution resistance level of the insulator surface.

[0074] In a further preferred but non-limiting embodiment, the step five specifically comprises:

[0075] According to the pollution resistance evaluation results, the characterization color scale is defined and pseudo-color processing is performed to obtain the visualization results of the pollution resistance level of the insulator surface.

[0076] For composite insulators, the hydrophobicity of the vulcanized silicone rubber surface will decrease due to aging, and this hydrophobicity will be reflected in the attenuation change law of the wetness of the dirt layer. Therefore, for the evaluation of pollution resistance, it is necessary to consider not only the feasibility of obtaining actual spectral images, but also the factor of hydrophobicity (aging) of the dirt base layer. The present invention provides an insulator pollution resistance evaluation method that dynamically shoots and rates the wetness of the dirt layer by combining active thermal light sources and multi-spectral imaging to obtain the insulation pollution resistance level, which is a new idea and technical means.

[0077] In Example 2, based on the method described in Example 1, the following specific embodiments are provided:

[0078] 1. Equipment preparation and setup:

[0079] Prepare a high-power halogen light source and ensure that its light pulse peak power is not less than 1500W and the total energy in the irradiated area is not less than 15J.

[0080] Prepare multispectral imaging equipment for continuous monitoring of changes in insulator surface reflectivity.

[0081] 2. Pulse irradiation:

[0082] The surface of the vulcanized silicone rubber composite insulator sheet that was slightly contaminated and unevenly corona aged was pulsed to ensure that the light pulses met the above power and energy requirements. At this time, the relative humidity of the atmosphere was 55%.

[0083] 3. Multispectral imaging monitoring:

[0084] The insulator surface is continuously monitored using multispectral imaging equipment to record the change in reflectivity of each pixel over time.

[0085] 4. Relative reflectivity calculation:

[0086] For a specific wavelength sequence (458.5, 543.2, 671.5, 750.5, 915.3, 997.9nm), calculate the insulator surface reflectivity R(λ i ) and the standard gray plate reflectivity R0(λ i ), and the relative reflectivity is obtained:

[0087]

[0088] Taking a target area at t = 0 as an example, we can calculate: R′≈0.87

[0089] 5. Calculation of water content:

[0090] Taking a target area at t=0 as an example, the calculation results are:

[0091]

[0092] 6.Moisture content decay rate fitting:

[0093] The data of the change of water content MC with time t are: MC(0,1,2,3,4,5,6,7,8,9,10)=0.208,0.201,0.194,0.185,0.174,0.169,0.165,0.160,0.153,0.158. The parameter fitting was performed and the fitting result was D=1.31.

[0094] 7. Evaluation of stain resistance:

[0095] The pollution resistance of the insulator surface is graded and evaluated according to the D value obtained by fitting. For the vulcanized silicone rubber composite insulator, D=0.1 in the corresponding area falls within the range of (0,3.5], so the pollution resistance level of the target area is Class I, which is poor.

[0096] 8. Visualization processing:

[0097] like Figure 1 As shown in the figure, according to the pollution resistance evaluation results, the characterization color scale is defined, and pseudo-color processing is performed to obtain the visualization results of the pollution resistance level of each area of ​​the insulator.

[0098] In Example 3, the present invention provides an insulator pollution resistance evaluation system, based on the insulator pollution resistance evaluation method described in Example 1, the system includes:

[0099] A high-power halogen light source, a multi-spectral imaging device, a moisture attenuation rate calculation module, a grading evaluation module and a visualization module, wherein the high-power halogen light source is used to perform pulse irradiation on the insulator surface, the multi-spectral imaging device is used to continuously monitor the insulator surface, the moisture attenuation rate calculation module is used to calculate the moisture attenuation rate based on the monitoring data, the grading evaluation module is used to perform graded evaluation on the pollution resistance of the insulator surface based on the moisture attenuation rate, and the visualization module is used to perform pseudo-color processing based on the evaluation results and output the visualization results of the pollution resistance level of the insulator surface.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the surface pollution resistance of an insulator, characterized in that: The steps include: Use a high-power halogen light source to pulse irradiate the insulator surface; Continuous monitoring of the insulator surface by multi-spectral imaging equipment; The water content attenuation rate D is calculated based on the monitoring data obtained by the multi-spectral imaging equipment; The pollution resistance of the insulator surface is graded and evaluated according to the calculated moisture content attenuation rate D; Pseudo-color processing is performed based on the evaluation results to obtain the visualization results of the pollution resistance level of the insulator surface.

2. The method for evaluating the surface pollution resistance of an insulator according to claim 1, characterized in that: The light pulse wavelength range of the high-power halogen light source covers 900nm to 2.5μm, the peak power is not less than 1500W, and the total energy in the irradiated area is not less than 15J.

3. The method for evaluating the surface pollution resistance of an insulator according to claim 1, characterized in that: The monitoring data obtained by the multi-spectral imaging device includes the insulator surface at the characteristic wavelength λ obtained by continuous shooting within a period of time t. i The reflectivity R under.

4. A method for evaluating the surface pollution resistance of an insulator according to claim 1 or 3, characterized in that: The water content attenuation rate D is obtained by exponential fitting, and the specific fitting function form is: MC(t)=MC0exp(C-Dt) Among them, MC(t) is the water content at time t after irradiation by the light source, MC0 is the relative reflectivity at the initial moment after irradiation by the halogen light source, C is the fitting delay, t represents time, and D is the water content attenuation rate.

5. The method for evaluating the surface pollution resistance of an insulator according to claim 4, characterized in that: The calculation formula of the water content MC is: Among them, A is -0.7123; B is 2.889, A and B are empirical parameters; R′ is the relative spectral reflectance.

6. The method for evaluating the surface pollution resistance of an insulator according to claim 5, characterized in that: The relative spectral reflectance R′ is the value of λ at a specific wavelength. i The root mean square of the ratio of the reflectivity R of the standard gray plate to the reflectivity R0 is calculated as follows: Where N is the number of units in the characteristic wavelength sequence, λ i is the characteristic wavelength.

7. The method for evaluating the surface pollution resistance of an insulator according to claim 6, characterized in that: The characteristic wavelength λ i Including 458.5nm, 543.2nm, 671.5nm, 750.5nm, 915.3nm and 997.9nm.

8. The method for evaluating the surface pollution resistance of an insulator according to claim 1, characterized in that: The evaluation standard for the insulator surface pollution resistance trace is: When D∈(0,a1], the stain resistance level is level I, indicating that the stain resistance level is poor; When D∈(a1,a2], the stain resistance level is level II, indicating that the stain resistance level has decreased significantly; When D∈(a2,a3], the stain resistance level is level III, indicating that the stain resistance level is slightly decreased; When D∈(a3,a4], the stain resistance level is IV, indicating a good stain resistance level.

9. The method for evaluating the surface pollution resistance of an insulator according to claim 8, characterized in that: For vulcanized silicone rubber composite insulators, the values ​​of a1 to a4 are include: a1=3.5, a2=6, a3=9.5, a4=13; For ceramic insulators, the values ​​of a1 to a4 include: a1=2.5, a2=4.5, a3=7, a4=10.

10. An insulator surface pollution resistance evaluation system, based on an insulator surface pollution resistance evaluation method according to any one of claims 1 to 9, characterized in that: The system includes: A high-power halogen light source, a multi-spectral imaging device, a moisture attenuation rate calculation module, a grading evaluation module and a visualization module, wherein the high-power halogen light source is used to perform pulse irradiation on the insulator surface, the multi-spectral imaging device is used to continuously monitor the insulator surface, the moisture attenuation rate calculation module is used to calculate the moisture attenuation rate based on the monitoring data, the grading evaluation module is used to perform graded evaluation on the pollution resistance of the insulator surface based on the moisture attenuation rate, and the visualization module is used to perform pseudo-color processing based on the evaluation results and output the visualization results of the pollution resistance level of the insulator surface.

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