High-sensitivity leakage insulation detection method and device for switchgear

Abstract

The present invention relates to the technical field of leakage detection, and particularly relates to a highly sensitive leakage insulation detection method and device for switch cabinets. This method adopts a traversal and screening strategy to obtain all ultraviolet images in different wavelength ranges. First, it analyzes the overlapping situation of each spot area, and then determines the clarity of each spot area. Further, considering that the corona area usually occurs around electrical equipment, the initial anti-noise level is corrected by distance to obtain the final anti-noise level, and then the optimal filter is selected for leakage detection. The present invention statistically analyzes the distribution characteristics of the spot areas under different filters, screens out the optimal filter that is not affected by noise, and thereby improves the sensitivity of leakage detection.

Description

Technical Field

[0001] The present invention relates to the technical field of leakage detection, and particularly relates to a highly sensitive leakage insulation detection method and device for switch cabinets. Background Art

[0002] When electrical equipment in a switch cabinet operates under high voltage, corona discharge, that is, leakage, will occur due to the concentration of the electric field. When corona discharge occurs, nitrogen molecules in the air are excited to generate ultraviolet light radiation. The ultraviolet detector can detect these ultraviolet light signals, thereby realizing the detection of corona discharge. By measuring the ultraviolet radiation intensity and the discharge current, the characteristics and intensity of the discharge can be analyzed.

[0003] The wavelength range of ultraviolet light is 10nm - 400nm. From the typical discharge spectrum, it can be known that corona can be detected in the wavelength range of 200nm - 400nm. However, sunlight or other external light sources are also strong ultraviolet radiation sources. The part with a wavelength less than 280nm is absorbed by the atmosphere. Therefore, only the ultraviolet band of 280nm - 400nm can be transmitted through the atmosphere. The wavelength range below 280nm is called the "solar blind" area. Therefore, in order to realize the discharge detection of switch cabinet equipment under sunlight, generally, the solar blind area is utilized, and the data with a wavelength working between 200nm - 280nm is collected by filtering to remove the interference of other spectra for the leakage detection of the switch cabinet. However, from the actually obtained typical discharge spectrum, it is known that the reaction of the corona phenomenon in the solar blind area is relatively small. It is only because the interference in the solar blind area is relatively small that the solar blind area band is used for analysis. Therefore, in order to improve the sensitivity of leakage detection, in fact, a larger range of bands should be set for detection and analysis. However, an unreasonable setting of the band will also cause the influence of noise such as sunlight. Summary of the Invention

[0004] In order to solve the technical problem that the prior art cannot reasonably set an effective filter band to improve the sensitivity of leakage detection, the purpose of the present invention is to provide a highly sensitive leakage insulation detection method and device for switch cabinets, and the specific technical solutions adopted are as follows:

[0005] The present invention proposes a highly sensitive leakage insulation detection method for switch cabinets, and the method includes:

[0006] Obtain ultraviolet light images of electrical equipment in a switch cabinet under filters with different wavelength ranges, and the ultraviolet light images include multiple spot areas;

[0007] For each spot area on each ultraviolet image, obtain the overlapping situation of the spot area in different ultraviolet images according to the position of the spot area; obtain the clarity of each spot area according to the overlapping situation of the spot area and the gradient of the area boundary in the ultraviolet image;

[0008] For each ultraviolet image, determine the initial anti-noise degree according to the clarity and overlapping situation of the spot area, and correct the initial anti-noise degree according to the distance between the spot area and the electrical equipment in the ultraviolet image to obtain the final anti-noise degree of each ultraviolet image;

[0009] Select the optimal ultraviolet image under the optimal filter for leakage detection according to the final anti-noise degree.

[0010] Further, the method for obtaining the spot area includes:

[0011] Use the Otsu threshold algorithm to obtain a binary image after threshold segmentation of the ultraviolet image, and the area corresponding to the connected domain in the binary image in the ultraviolet image is the spot area.

[0012] Further, the method for obtaining the overlapping situation includes:

[0013] Take any spot area on any ultraviolet image as the target area; the spot areas that belong to different ultraviolet images from the target area are used as comparison areas;

[0014] During the overlapping process of all ultraviolet images, if there is an intersection between the target area and the comparison area, then use the filter of the ultraviolet image corresponding to the comparison area with the intersection as the effective filter of the target area; perform a negative correlation mapping on the wavelength ranges of the effective filter and the filter corresponding to the target area and accumulate to obtain an overlapping eigenvalue; use the union between the target area and the comparison area with the intersection as the overall overlapping area; the overlapping eigenvalue and the overlapping area are used as the overlapping situation.

[0015] Further, the method for obtaining the clarity includes:

[0016] Accumulate the gradient amplitudes of the edge pixel points of the spot area to obtain an overall gradient value, and use the product of the overall gradient value and the overlapping eigenvalue as the clarity.

[0017] Further, the method for obtaining the initial anti-noise degree includes:

[0018] Obtain the area ratio of the area of the spot area to the overall overlapping area, and multiply the area ratio by the clarity to obtain the initial anti-noise degree.

[0019] Further, the method for obtaining the final anti-noise degree includes:

[0020] Perform a negative correlation mapping and normalization on the distance between the light spot area and the electrical equipment in the ultraviolet image to obtain a distance weight; perform a weighted sum of the initial anti-noise degrees of all light spot areas in the ultraviolet image according to the distance weight to obtain the final anti-noise degree.

[0021] Further, the selection of the optimal ultraviolet image under the optimal filter for leakage detection according to the final anti-noise degree includes:

[0022] Integrate the corona discharge spectral function in each wavelength range to obtain the response characteristics of each filter, and use the product of the response characteristics and the final anti-noise degree as the preference degree; select the optimal filter according to the preference degree.

[0023] Further, select the filter with the largest preference degree as the optimal filter.

[0024] Further, the method for leakage detection includes:

[0025] Perform threshold segmentation on the ultraviolet image under the optimal filter to obtain a highlighted area, and the pixel points in the highlighted area are abnormal photon pixel points; if the number of the abnormal photon pixel points is greater than a preset number threshold, feedback a leakage warning.

[0026] The present invention also provides a highly sensitive leakage and insulation detection device for a switch cabinet, and the device includes a filter switching module, an ultraviolet sensor, and a data processing module; the filter switching module includes filter lenses with multiple different wavelength ranges, and the ultraviolet sensor is used to receive signals after the ultraviolet rays are filtered by the filter lenses; the data processing module is used to execute any one of the highly sensitive leakage and insulation detection methods for a switch cabinet.

[0027] The present invention has the following beneficial effects:

[0028] The present invention adopts a traversal and screening strategy. First, all ultraviolet images in different wavelength ranges are obtained. For the corona region generated by leakage, it should have obvious discharge visual effects under multiple filters. Therefore, the present invention first analyzes the overlapping situation of each spot region, and then determines the clarity of each spot region. The greater the clarity, the less affected by noise under this filter, and the more likely the collected spot region is the real corona region. Further considering that the corona region usually occurs around electrical equipment, the initial anti-noise degree can be corrected by distance to obtain the final anti-noise degree, and then the optimal filter is selected for leakage detection. The present invention statistically analyzes the distribution characteristics of the spot regions under different filters, screens out the optimal filter that is not affected by noise, and thus improves the sensitivity of leakage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 Flowchart of a highly sensitive leakage insulation detection method for switchgear provided by an embodiment of the present invention;

[0031] Figure 2 Structural diagram of a highly sensitive leakage insulation detection device for switchgear provided by an embodiment of the present invention;

[0032] Figure 3 An ultraviolet image provided by an embodiment of the present invention;

[0033] Figure 4 Provided by an embodiment of the present invention Figure 3 Binary image;

[0034] Figure 5 Comparison schematic diagram of binary images under different filters provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following specifically describes, in conjunction with the accompanying drawings and preferred embodiments, a highly sensitive leakage insulation detection method and device for a switchgear cabinet, including its specific implementation manner, structure, features, and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0037] The following specifically describes the specific solution of a highly sensitive leakage insulation detection method and device for a switchgear cabinet provided by the present invention in conjunction with the accompanying drawings.

[0038] First, please refer to Figure 2 , which shows the structural diagram of a highly sensitive leakage insulation detection device for a switchgear cabinet provided by an embodiment of the present invention. Figure 2 The device includes a housing 1, a data processing module 2, a rotating shaft 3, a filter switching module 4, an ultraviolet sensor 5, and a positioning gear 6. Among them, in the filter switching module 4, multiple filters with different wavelength bands are positioned by the positioning gear 6. The ultraviolet sensor 5 is fixedly arranged, and by rotating the rotating shaft 2, the ultraviolet sensor can receive signals after filtering ultraviolet light under different filter lenses. After the ultraviolet sensor 5 receives the ultraviolet signal, it can generate an ultraviolet light image through signal conversion. In the embodiment of the present invention, the filter switching module includes filters in 7 wavelength bands, and the specific wavelength band ranges include: 200 - 400, 200 - 380, 200 - 360, 200 - 340, 200 - 320, 200 - 300, 200 - 280. The data processing module 2 can execute the algorithm of a highly sensitive leakage insulation detection method for a switchgear cabinet in the embodiment of the present invention.

[0039] Please refer to Figure 1 , which shows the flowchart of a highly sensitive leakage insulation detection method for a switchgear cabinet provided by an embodiment of the present invention. The method includes:

[0040] Step S1: Obtain ultraviolet light images of electrical equipment in a switchgear cabinet under filters with different wavelength ranges. The ultraviolet light images contain multiple light spot regions.

[0041] The filter can filter out ultraviolet rays outside the wavelength range. When the ultraviolet rays within the wavelength range are acquired by the sensor, a corona phenomenon will produce obvious highlights in the generated ultraviolet image. Therefore, the ultraviolet image can be regarded as containing three types of information: electrical equipment information with darker pixel values, highlight information generated by the corona phenomenon, and noise information. The embodiments of the present invention aim to screen out the optimal ultraviolet image under the optimal filter without noise interference, that is, the noise information in the optimal ultraviolet image is the least, and the highlight information generated by the corona phenomenon has the strongest reference. Therefore, in order to find the optimal ultraviolet image, it is necessary to analyze each ultraviolet image to determine whether the characteristics of the spot area therein show the characteristics of the corona phenomenon. The spot area has a strong pixel value difference from other information, so the spot area can be directly obtained through the pixel value.

[0042] Preferably, in the embodiments of the present invention, the Otsu threshold algorithm is used to obtain the binary image after threshold segmentation of the ultraviolet image, and the area corresponding to the connected domain in the binary image in the ultraviolet image is the spot area. Please refer to Figure 3 , which shows an ultraviolet image provided by an embodiment of the present invention. Please refer to Figure 4 , which shows the Figure 3 binary image provided by an embodiment of the present invention. It should be noted that, for the convenience of comparison, Figure 4 the pixel value of the spot area in is 0.

[0043] Step S2: For each spot area on each ultraviolet image, obtain the overlapping situation of the spot area in different ultraviolet images according to the position of the spot area; obtain the clarity of each spot area according to the overlapping situation of the spot area and the gradient of the area boundary in the ultraviolet image.

[0044] Please refer to Figure 5 , which shows a comparison schematic diagram of binary images under different filters provided by an embodiment of the present invention. For a spot area on a certain ultraviolet image, if the spot area appears in the ultraviolet images under different filters, it is said that the spot area is a corona area with obvious characteristics. Therefore, the embodiments of the present invention analyze the overlapping situation of the position where a certain spot area is located in different ultraviolet images. If there are multiple spot areas overlapping at a certain position, it means that the corresponding spot area at that position is more likely to be a corona area. Further, if the overlapping degree of a certain spot area is large and the edge of the area is clearer, it means that under this filter, the ultraviolet characteristics reflected by the corona phenomenon are clearer, and the spot area is more likely to be a real corona area and is less affected by noise. Therefore, the embodiments of the present invention can further determine the clarity of each spot area according to the overlapping situation of the spot area and the gradient information of the area boundary in the ultraviolet image. By quantifying the clarity, the obvious degree of the corona characteristics of the spot area can be characterized indirectly.

[0045] Preferably, in the embodiments of the present invention, considering that the overlapping situation can be divided into features in two dimensions: the overlapping state and the overlapping area, the method for obtaining the overlapping situation includes:

[0046] Taking any light spot area on any ultraviolet image as the target area; and taking the light spot areas that belong to different ultraviolet images from the target area as the comparison areas.

[0047] During the overlapping process of all ultraviolet images, if there is an intersection between the target area and the comparison areas, it indicates that partial overlap occurs between the two areas. The filter of the ultraviolet image corresponding to the comparison area with the intersection is taken as the effective filter of the target area. The more effective filters there are, it means that more light spot areas overlap, and the overlapping state is richer. The embodiments of the present invention further consider the wavelength range of the filter. The larger the wavelength range, it means that it is more likely to be affected by noise wavelengths under this filter, and there may be interference of noise information in the overlapping union of the two areas. Therefore, the wavelength ranges of the effective filter and the filter corresponding to the target area are negatively correlated and mapped and accumulated to obtain the overlapping feature value. That is, the larger the overlapping feature value, it means that under the filters with a limited wavelength range, there are more filters that can transmit the band information in the light spot area, and the more likely this target area is a corona area.

[0048] Taking the union between the target area and the comparison areas with intersections as the overall overlapping area. That is, the smaller the overlapping area, it means that the two areas overlap more, and the more likely this light spot area is a complete corona area.

[0049] Taking the overlapping feature value and the overlapping area as the overlapping situation.

[0050] It should be noted that in the embodiments of the present invention, the method of negative correlation mapping and normalization can be implemented by using an exponential function with the natural constant as the base. Taking the opposite number of the data as the power of this exponential function, the function output value is the result of negative correlation mapping and normalization. Those skilled in the art can choose other conventional basic mathematical means to achieve the purpose of negative correlation or normalization by themselves, and will not be elaborated here.

[0051] Furthermore, the embodiments of the present invention can obtain the clarity by combining the overlapping feature value and the gradient value of the edge of the light spot area, specifically including: accumulating the gradient amplitudes of the edge pixel points of the light spot area to obtain the overall gradient value. The larger the overall gradient value, it means that the edge of the light board area is clearer, and the greater the clarity. Further, the overlapping feature value can be regarded as a weight to weight the overall gradient value, and the product of the overall gradient value and the overlapping feature value is taken as the clarity.

[0052] Step S3: For each ultraviolet image, determine the initial anti-noise level according to the clarity and overlap of the light spot area, and correct the initial anti-noise level according to the distance between the light spot area and the electrical equipment in the ultraviolet image to obtain the final anti-noise level of each ultraviolet image.

[0053] In step S2, the clarity and overlap of each spot area on each ultraviolet image can be quantified. If the spot areas on an ultraviolet image all show more overlap and clearer edges, it means that the filter corresponding to the ultraviolet image is a filter suitable for observation. Therefore, the features obtained from all spot areas on each ultraviolet image are further counted to obtain the initial noise resistance of the current ultraviolet image. That is, the clearer the spot area and the more obvious the overlap, the greater the initial noise resistance.

[0054] Further considering that the corona area should occur around the electrical equipment, the closer the spot area is to the electrical equipment in the ultraviolet light image, the more likely it is that the spot area is a corona area. Therefore, the initial anti-noise level can be corrected according to the distance between the spot area and the electrical equipment in the ultraviolet light image, thereby obtaining the final anti-noise level of each ultraviolet light image.

[0055] It should be noted that, in the embodiment of the present invention, the electrical equipment in the ultraviolet image can be identified by means of semantic recognition, image segmentation, etc., and the distance between the center point of the electrical equipment area and the center point of the spot area is used as the distance used for correction. The identification of the electrical equipment and the distance calculation method are both technical means well known to those skilled in the art, and will not be elaborated here.

[0056] Preferably, the method for obtaining the initial noise immunity level in the embodiment of the present invention includes:

[0057] The area ratio of the spot area to the overall overlapping area is obtained. The larger the area ratio, the larger the spot area is in the overall overlapping area, indicating that the position of the spot area has obvious characteristics under multiple filters, and the spot area is more likely to be a corona area, and the corresponding filter has a greater degree of noise resistance.

[0058] Further combined with the clarity, the area ratio is multiplied by the clarity to obtain the initial noise resistance level. That is, each spot area corresponds to an initial noise resistance level.

[0059] Preferably, in an embodiment of the present invention, the method for obtaining the final noise immunity level includes:

[0060] Negatively correlate and normalize the distance between the light spot area and the electrical equipment in the ultraviolet image to obtain a distance weight. That is, the closer the distance, the greater the distance weight. Weighted sum the initial noise resistance degrees of all light spot areas in the ultraviolet image according to the distance weight to obtain the final noise resistance degree. That is, each ultraviolet image can correspond to a final noise resistance degree, and the greater the final noise resistance degree, the more likely the filter corresponding to the ultraviolet image is a suitable filter.

[0061] Step S4: Select the optimal ultraviolet image under the optimal filter according to the final noise resistance degree for leakage detection.

[0062] By quantifying the final noise resistance degree through the above steps, a filter with a larger final noise resistance degree can be selected as the optimal filter, and leakage detection can be performed based on the optimal ultraviolet image under the optimal filter.

[0063] Preferably, in the embodiments of the present invention, further considering that the response of the typical corona discharge spectrum can be analyzed under the wavelength range of each filter, integrate the corona discharge spectrum function in each wavelength range to obtain the response characteristics of each filter. That is, the response characteristics can be regarded as the area enclosed by the corona discharge spectrum function and the horizontal axis within the wavelength range. The corona discharge spectrum function is statistical data from existing materials, with the horizontal axis being the wavelength and the vertical axis being the relative intensity. The specific content is well-known technical information to those skilled in the art and will not be elaborated here. Multiply the response characteristics by the final noise resistance degree as the preference degree; select the optimal filter according to the preference degree.

[0064] In the embodiments of the present invention, the filter with the largest preference degree is selected as the optimal filter.

[0065] It should be noted that in other embodiments of the present invention, considering that although the environmental information is relatively stable during the leakage detection of the switch cabinet, it will also change over time, it is necessary to adjust the obtained optimal filter according to the environmental changes. Therefore, a time interval of 30 minutes is set, and the optimal filter is re-determined every 30 minutes to ensure the accuracy and sensitivity of the detection. The time interval can be adjusted according to the actual situation. Additionally, in other embodiments of the present invention, a photoresistor can also be set. When the photoresistor detects a change in light intensity, the optimal filter is re-determined, which can also cope with environmental changes.

[0066] Preferably, in the embodiments of the present invention, the method for leakage detection includes:

[0067] Perform threshold segmentation on the ultraviolet image under the optimal filter to obtain a highlighted area, and the pixel points in the highlighted area are abnormal photon pixel points; if the number of abnormal photon pixel points is greater than a preset number threshold, a leakage warning is fed back. In the embodiment of the present invention, the number of abnormal photon pixel points is converted into the number of abnormal photons through the proportion of the actual switchgear electrical equipment in the image field of view, and the number threshold is set to 2000, and an alarm is triggered when the number of abnormal photons is greater than 2000. Among them, the alarm can be divided into a sound alarm, a visual alarm formed by a light, and an alarm fed back to the staff on the device terminal.

[0068] In summary, the present invention adopts a strategy of traversing and screening to obtain all ultraviolet images in different wavelength ranges. First, analyze the overlapping situation of each spot area, and then determine the clarity of each spot area. Further considering that the corona area usually occurs around the electrical equipment, the initial anti-noise level is corrected by distance to obtain the final anti-noise level, and then the optimal filter is selected for leakage detection. The present invention statistically analyzes the distribution characteristics of the spot areas under different filters, selects the optimal filter that is not affected by noise, and thereby improves the sensitivity of leakage detection.

[0069] It should be noted that: the above sequence of embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0070] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

Claims

1. A highly sensitive leakage insulation detection method for switchgear, characterized in that, The method includes: Obtaining ultraviolet light images of electrical equipment in a switchgear cabinet under filters in different wavelength ranges, where the ultraviolet light images contain multiple spot regions; For each spot region on each ultraviolet light image, obtaining the overlapping situation of the spot region in different ultraviolet light images according to the position of the spot region; obtaining the clarity of each spot region according to the overlapping situation of the spot region and the gradient of the region boundary in the ultraviolet light image; For each ultraviolet light image, determining an initial anti-noise degree according to the clarity and overlapping situation of the spot region, and correcting the initial anti-noise degree according to the distance between the spot region and the electrical equipment in the ultraviolet light image to obtain the final anti-noise degree of each ultraviolet light image; Selecting the optimal ultraviolet light image under the optimal filter for leakage detection according to the final anti-noise degree; The method for obtaining the overlapping situation includes: Taking any spot region on any ultraviolet light image as a target region; and taking the spot regions that belong to different ultraviolet light images from the target region as comparison regions; During the overlapping process of all ultraviolet light images, if there is an intersection between the target region and a comparison region, taking the filter of the ultraviolet light image corresponding to the comparison region with the intersection as the effective filter of the target region; performing a negative correlation mapping and accumulation on the wavelength ranges of the effective filter and the filter corresponding to the target region to obtain an overlapping eigenvalue; taking the union between the target region and the comparison regions with intersections as the overall overlapping area; the overlapping eigenvalue and the overlapping area are used as the overlapping situation; The method for obtaining the clarity includes: Accumulating the gradient amplitudes of the edge pixel points of the spot region to obtain an overall gradient value, and taking the product of the overall gradient value and the overlapping eigenvalue as the clarity; The method for obtaining the initial anti-noise degree includes: Obtaining the area ratio of the area of the spot region to the overall overlapping area, and multiplying the area ratio by the clarity to obtain the initial anti-noise degree; The method for obtaining the final anti-noise degree includes: Performing a negative correlation mapping and normalization on the distance between the spot region and the electrical equipment in the ultraviolet light image to obtain a distance weight; performing a weighted sum of the initial anti-noise degrees of all spot regions in the ultraviolet light image according to the distance weight to obtain the final anti-noise degree; The selecting the optimal ultraviolet light image under the optimal filter for leakage detection according to the final anti-noise degree includes: Integrating the corona discharge spectral function in each wavelength range to obtain the response characteristics of each filter, and taking the product of the response characteristics and the final anti-noise degree as the preference degree; selecting the optimal filter according to the preference degree.

2. The highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that The method for obtaining the spot region includes: Using the Otsu threshold algorithm to obtain a binary image after threshold segmentation of the ultraviolet light image, and the region corresponding to the connected domain in the binary image in the ultraviolet light image is the spot region.

3. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that, Selecting the filter with the largest preference degree as the optimal filter.

4. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that, The method for leakage detection includes: Perform threshold segmentation on the ultraviolet light image under the optimal filter to obtain a highlighted area, and the pixel points in the highlighted area are abnormal photon pixel points; if the number of the abnormal photon pixel points is greater than a preset number threshold, a leakage warning is fed back.

5. A highly sensitive leakage insulation detection device for switchgear, characterized in that, The device includes a filter switching module, an ultraviolet sensor, and a data processing module; the filter switching module includes filter lenses with multiple different wavelength ranges, and the ultraviolet sensor is used to receive signals after the ultraviolet rays are filtered by the filter lenses; the data processing module is used to execute a highly sensitive leakage insulation detection method for switch cabinets according to any one of claims 1-4.

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