High-sensitivity electric leakage insulation detection method and device for switch cabinet

Abstract

The invention relates to the technical field of electric leakage detection, in particular to a high-sensitivity electric leakage insulation detection method and device for a switch cabinet. According to the method, a traversal screening strategy is adopted, all ultraviolet images in different wavelength ranges are obtained, the overlapping condition of each light spot area is analyzed firstly, then the clear degree of each light spot area is determined, and it is further considered that a corona area usually occurs around electric equipment, so that the accuracy of the electric equipment is improved. The initial anti-noise degree is corrected through the distance to obtain the final anti-noise degree, and then the optimal filter is screened out for electric leakage detection. According to the invention, statistical analysis is carried out on the distribution characteristics of the light spot areas under different filters, and the optimal filter which is not influenced by noise is screened out, so that the sensitivity of electric leakage detection is improved.

Description

Technical Field

[0001] The invention relates to the technical field of leakage detection, and in particular to a high-sensitivity leakage insulation detection method and device for a switch cabinet. Background Art

[0002] When the electrical equipment in the switch cabinet is running at high voltage, corona discharge, i.e. leakage, will occur due to the concentration of electric field. When corona discharge occurs, nitrogen molecules in the air are excited and generate ultraviolet radiation. Ultraviolet detectors can detect these ultraviolet light signals, thereby realizing the detection of corona discharge. By measuring the intensity of ultraviolet radiation and 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, we know that the wavelength in the region of 200nm-400nm can be used to detect corona, but sunlight or other external light sources are also strong sources of ultraviolet radiation, and the part with a wavelength less than 280nm is absorbed by the atmosphere, so only the ultraviolet band of 280nm-400nm can be transmitted through the atmosphere, and 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, the solar blind area is generally used, and the data with a wavelength working between 200nm-280nm is collected by filtering, and the interference of other spectra is removed to perform leakage detection of the switch cabinet. However, from the typical discharge spectrum actually obtained, 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, a larger range of bands should actually be set for detection and analysis. However, unreasonable band settings will also lead to 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 high-sensitivity leakage insulation detection method and device for a switch cabinet. The technical solution adopted is as follows: The present invention proposes a highly sensitive leakage insulation detection method for a switch cabinet, the method comprising: Acquire ultraviolet images of electrical equipment in the switch cabinet under filters in different wavelength ranges, wherein the ultraviolet images contain multiple light spot areas; For each light spot area on each ultraviolet image, the overlapping of the light spot areas in different ultraviolet images is obtained according to the positions of the light spot areas; the clarity of each light spot area is obtained according to the overlapping of the light spot areas and the gradient of the area boundary in the ultraviolet image; For each ultraviolet image, an initial anti-noise degree is determined according to the clarity and overlap of the light spot area, and the initial anti-noise degree is corrected according to the distance between the light spot area and the electrical equipment in the ultraviolet image to obtain a final anti-noise degree of each ultraviolet image; The optimal UV image under the optimal filter is selected for leakage detection according to the final anti-noise level.

[0005] Furthermore, the method for acquiring the light spot area includes: The binary image of the ultraviolet light image after threshold segmentation is obtained by using the Otsu threshold algorithm, and the area corresponding to the connected domain in the binary image in the ultraviolet light image is the light spot area.

[0006] Furthermore, the method for obtaining the overlapping situation includes: Any spot area on any ultraviolet image is taken as a target area; the spot area belonging to a different ultraviolet image from the target area is taken as a comparison area; During the overlapping process of all ultraviolet images, if there is an intersection between the target area and the contrast area, the filter of the ultraviolet image corresponding to the contrast area with the intersection is used as the effective filter of the target area; the wavelength ranges of the effective filter and the filter corresponding to the target area are negatively correlated and accumulated to obtain the overlapping characteristic value; the union between the target area and the contrast area with the intersection is used as the overall overlapping area; the overlapping characteristic value and the overlapping area are used as the overlapping situation.

[0007] Furthermore, the method for obtaining the clarity includes: The gradient amplitudes of the edge pixels of the light spot area are accumulated to obtain an overall gradient value, and the product of the overall gradient value and the overlapping feature value is used as the clarity.

[0008] Furthermore, the method for obtaining the initial noise immunity level includes: The area ratio of the area of ​​the light spot region to the overall overlapping area is obtained, and the area ratio is multiplied by the clarity to obtain the initial anti-noise degree.

[0009] Furthermore, the method for obtaining the final noise immunity level includes: The distance between the spot area and the electrical equipment in the ultraviolet image is negatively correlated and normalized to obtain a distance weight; the initial anti-noise degree of all the spot areas in the ultraviolet image is weighted and summed according to the distance weight to obtain the final anti-noise degree.

[0010] Further, the selecting the optimal ultraviolet light image under the optimal filter for leakage detection according to the final anti-noise degree includes: Integrate the corona discharge spectrum function in each wavelength range to obtain the response characteristics of each filter, and take the product of the response characteristics and the final anti-noise degree as the optimization degree; select the optimal filter according to the optimization degree.

[0011] Further, the filter with the highest preference degree is selected as the optimal filter.

[0012] Furthermore, the leakage detection method includes: The ultraviolet light image under the optimal filter is threshold segmented to obtain a highlight area, and the pixels in the highlight area are abnormal photon pixels; if the number of the abnormal photon pixels is greater than the preset number threshold, a leakage warning is fed back.

[0013] The present invention also proposes a high-sensitivity leakage insulation detection device for a switch cabinet, the device comprising a filter switching module, an ultraviolet sensor and a data processing module; the filter switching module comprises a plurality of filter lenses with different wavelength ranges, and the ultraviolet sensor is used to receive signals after the filter lenses filter ultraviolet rays; the data processing module is used to execute any one of the high-sensitivity leakage insulation detection methods for a switch cabinet.

[0014] The present invention has the following beneficial effects: The present invention adopts a traversal screening strategy, firstly obtaining all ultraviolet images under different wavelength ranges. For the corona area generated by leakage, it should have obvious discharge visual effects under multiple filters. Therefore, the present invention first analyzes the overlap of each spot area, and then determines the clarity of each spot area. The greater the clarity, the less affected by noise under the filter, and the more likely the collected spot area is to be a real corona area. Further considering that the corona area usually occurs around electrical equipment, the final anti-noise degree can be obtained by correcting the initial anti-noise degree through distance, and then the optimal filter is screened out for leakage detection. The present invention statistically analyzes the distribution characteristics of the spot area under different filters, and screens out the optimal filter that is not affected by noise, thereby improving the sensitivity of leakage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A flow chart of a highly sensitive leakage insulation detection method for a switch cabinet provided by one embodiment of the present invention; Figure 2 A structural diagram of a highly sensitive leakage insulation detection device for a switch cabinet provided by one embodiment of the present invention; Figure 3 An ultraviolet image provided by an embodiment of the present invention; Figure 4 An embodiment of the present invention provides Figure 3 A binary image of Figure 5 A schematic diagram of comparing binary images under different filters provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a high-sensitivity leakage insulation detection method and device for a switch cabinet proposed according to the present invention, its specific implementation method, structure, features and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0019] A specific scheme of a highly sensitive leakage insulation detection method and device for a switch cabinet provided by the present invention is described in detail below in conjunction with the accompanying drawings.

[0020] First see Figure 2 , which shows a structural diagram of a high-sensitivity leakage insulation detection device for a switch 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. In the filter switching module 4, a plurality of filters of different bands are positioned by the positioning gear 6, and the ultraviolet sensor 5 is fixedly arranged. By rotating the rotating shaft 2, the ultraviolet sensor can filter ultraviolet rays under different filter lenses and then receive signals. After receiving the ultraviolet signal, the ultraviolet sensor 5 can generate an ultraviolet light image through signal conversion. In an embodiment of the present invention, the filter switching module includes filters under 7 bands, and the specific band ranges include: 200-400, 200-380, 200-360, 200-340, 200-320, 200-300, and 200-280. The data processing module 2 can execute an algorithm of a high-sensitivity leakage insulation detection method for a switch cabinet in an embodiment of the present invention.

[0021] See also Figure 1 , which shows a flow chart of a high-sensitivity leakage insulation detection method for a switch cabinet provided by an embodiment of the present invention, the method comprising: Step S1: obtaining ultraviolet light images of electrical equipment in a switch cabinet under filters in different wavelength ranges, wherein the ultraviolet light images contain a plurality of light spot areas.

[0022] The filter can filter out ultraviolet rays that are not within the wavelength range. When ultraviolet rays within the wavelength range are captured by the sensor, the 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 embodiment of the present invention aims to screen out the optimal ultraviolet image under the optimal filter that is not interfered by noise, that is, the optimal ultraviolet image has the least noise information 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.

[0023] Preferably, in the embodiment of the present invention, the binary image of the ultraviolet image after threshold segmentation is obtained by using the Otsu threshold algorithm, and the area corresponding to the connected domain in the binary image in the ultraviolet image is the spot area. Figure 3 , which shows an ultraviolet image provided by an embodiment of the present invention, please refer to Figure 4 , which shows an embodiment of the present invention provides Figure 3 It should be noted that for the convenience of comparison, Figure 4 The pixel value of the spot area in is 0.

[0024] Step S2: for each spot area on each ultraviolet image, the overlap of the spot areas in different ultraviolet images is obtained according to the position of the spot area; the clarity of each spot area is obtained according to the overlap of the spot areas and the gradient of the area boundary in the ultraviolet image.

[0025] See also Figure 5, which shows a schematic diagram of the comparison 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, the spot area is said to be a corona area with obvious characteristics. Therefore, the embodiment of the present invention analyzes the overlap of the location of a certain spot area in different ultraviolet images. If there is an overlap of multiple spot areas at a certain position, it means that the corresponding spot area at this position is more likely to be a corona area. Further, if the degree of overlap of a certain spot area is large, and the edge of the area is clearer, it means that under this filter, the ultraviolet characteristics of the corona phenomenon feedback are clearer, and the spot area is more likely to be a real corona area, and the degree of noise influence is smaller. Therefore, the embodiment of the present invention can further determine the clarity of each spot area according to the overlap 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.

[0026] Preferably, in the embodiment of the present invention, considering that the overlapping situation can be divided into characteristics in two dimensions: overlapping state and overlapping area, the method for obtaining the overlapping situation includes: Any spot area on any ultraviolet image is taken as the target area; and the spot area belonging to a different ultraviolet image from the target area is taken as the comparison area.

[0027] During the overlapping process of all ultraviolet images, if there is an intersection between the target area and the contrast area, it means that the two areas have partially overlapped, and the filter of the ultraviolet image corresponding to the contrast area with the intersection is used as the effective filter of the target area. The more effective filters there are, the more light spot areas are overlapped, and the richer the overlapping state. The embodiment of the present invention further takes into account the wavelength range of the filter. The larger the wavelength range, the more likely it is that the filter will be affected by the noise wavelength, and the overlapping union of the two areas may be interfered by noise information. Therefore, the wavelength ranges of the effective filter and the filter corresponding to the target area are negatively correlated and accumulated to obtain the overlapping eigenvalue. That is, the larger the overlapping eigenvalue, the more filters can pass through the band information in the light spot area under the filter with a limited wavelength range, and the target area is more likely to be a corona area.

[0028] The union of the target area and the contrast area with intersection is taken as the overall overlapping area. That is, the smaller the overlapping area, the more the two areas overlap, and the more likely the spot area is a complete corona area.

[0029] The overlapping eigenvalues ​​and overlapping areas are taken as the overlapping conditions.

[0030] It should be noted that the method of negative correlation mapping and normalization in the embodiment of the present invention can be implemented by using an exponential function with a natural constant as the base, and the opposite number of the data is used as the power of the exponential function, and 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, which will not be elaborated here.

[0031] Furthermore, the embodiment of the present invention combines the overlapping eigenvalue and the gradient value of the edge of the spot area to obtain the clarity, specifically including: accumulating the gradient amplitude of the edge pixel points of the spot area to obtain the overall gradient value. The larger the overall gradient value, the clearer the edge of the light plate area, and the greater the clarity. The overlapping eigenvalue can be further regarded as a weight to the overall gradient value, and the product of the overall gradient value and the overlapping eigenvalue is used as the clarity.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Preferably, the method for obtaining the initial noise immunity level in the embodiment of the present invention includes: 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.

[0037] 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.

[0038] Preferably, in an embodiment of the present invention, the method for obtaining the final noise immunity level includes: The distance between the spot area and the electrical equipment in the ultraviolet image is negatively correlated and normalized to obtain the distance weight. That is, the closer the distance, the greater the distance weight. The initial anti-noise degree of all the spot areas in the ultraviolet image is weighted and summed according to the distance weight to obtain the final anti-noise degree. That is, each ultraviolet image can correspond to a final anti-noise degree. The greater the final anti-noise degree, the more likely the filter corresponding to the ultraviolet image is a suitable filter.

[0039] Step S4: Selecting the optimal ultraviolet light image under the optimal filter for leakage detection according to the final anti-noise degree.

[0040] By quantifying the final noise resistance through the above steps, a filter with a larger final noise resistance can be selected as an optimal filter, and leakage detection can be performed based on an optimal ultraviolet light image under the optimal filter.

[0041] Preferably, in the embodiment of the present invention, it is further considered that the response of the typical corona discharge spectrum can be analyzed under the wavelength range of each filter, and the corona discharge spectrum function is integrated under 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 the existing data obtained by statistics, the horizontal axis is the wavelength, and the vertical axis is the relative intensity. The specific content is the technical data well known to those skilled in the art, which will not be repeated here. The product of the response characteristics and the final anti-noise degree is taken as the preferred degree; the optimal filter is selected according to the preferred degree.

[0042] In the embodiment of the present invention, the filter with the highest preference degree is selected as the optimal filter.

[0043] It should be noted that in other embodiments of the present invention, considering that the environmental information is relatively stable during leakage detection of the switch cabinet, it will also change with time, and it is necessary to adjust the obtained preferred filter according to the changes in the environment. Therefore, the time interval is set to 30 minutes, 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. In addition, 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.

[0044] Preferably, in an embodiment of the present invention, the method for leakage detection includes: The ultraviolet image under the optimal filter is threshold segmented to obtain a highlight area, and the pixels in the highlight area are abnormal photon pixels; if the number of abnormal photon pixels is greater than the preset number threshold, a leakage warning is fed back. In an embodiment of the present invention, the abnormal photon pixels are converted into the number of abnormal photons through the proportion of the actual switch cabinet electrical equipment in the image field of view, and the number threshold is set to 2000. When the number of abnormal photons is greater than 2000, an alarm is triggered. The alarm can be divided into sound alarm, visual alarm formed by light, and alarm fed back to the staff's equipment terminal.

[0045] In summary, the present invention adopts a traversal screening strategy to obtain all ultraviolet images under different wavelength ranges, first analyzes the overlap of each spot area, and then determines the clarity of each spot area, and further considers that the corona area usually occurs around electrical equipment, and corrects the initial noise resistance by distance to obtain the final noise resistance, and then screens out the optimal filter for leakage detection. The present invention statistically analyzes the distribution characteristics of the spot area under different filters, and screens out the optimal filter that is not affected by noise, thereby improving the sensitivity of leakage detection.

[0046] It should be noted that the sequence of the above 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 results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0047] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

Claims

1. A highly sensitive leakage insulation detection method for a switch cabinet, characterized in that: The method comprises: Acquire ultraviolet images of electrical equipment in the switch cabinet under filters in different wavelength ranges, wherein the ultraviolet images contain multiple light spot areas; For each light spot area on each ultraviolet image, the overlapping of the light spot areas in different ultraviolet images is obtained according to the position of the light spot area; the clarity of each light spot area is obtained according to the overlapping of the light spot areas and the gradient of the area boundary in the ultraviolet image; For each ultraviolet image, an initial anti-noise degree is determined according to the clarity and overlap of the light spot area, and the initial anti-noise degree is corrected according to the distance between the light spot area and the electrical equipment in the ultraviolet image to obtain a final anti-noise degree of each ultraviolet image; The optimal UV image under the optimal filter is selected for leakage detection according to the final anti-noise level.

2. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that: The method for acquiring the light spot area comprises: The binary image of the ultraviolet light image after threshold segmentation is obtained by using the Otsu threshold algorithm, and the area corresponding to the connected domain in the binary image in the ultraviolet light image is the light spot area.

3. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that: The method for obtaining the overlapping situation includes: Any spot area on any ultraviolet image is taken as a target area; the spot area belonging to a different ultraviolet image from the target area is taken as a comparison area; During the overlapping process of all ultraviolet images, if there is an intersection between the target area and the contrast area, the filter of the ultraviolet image corresponding to the contrast area with the intersection is used as the effective filter of the target area; the wavelength ranges of the effective filter and the filter corresponding to the target area are negatively correlated and accumulated to obtain the overlapping characteristic value; the union between the target area and the contrast area with the intersection is used as the overall overlapping area; the overlapping characteristic value and the overlapping area are used as the overlapping situation.

4. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 3, characterized in that: The method for obtaining the clarity includes: The gradient amplitudes of the edge pixels of the light spot area are accumulated to obtain an overall gradient value, and the product of the overall gradient value and the overlapping feature value is used as the clarity.

5. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 3, characterized in that: The method for obtaining the initial noise immunity level includes: The area ratio of the area of ​​the light spot region to the overall overlapping area is obtained, and the area ratio is multiplied by the clarity to obtain the initial anti-noise degree.

6. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that: The method for obtaining the final noise immunity level includes: The distance between the spot area and the electrical equipment in the ultraviolet image is negatively correlated and normalized to obtain a distance weight; the initial anti-noise degree of all the spot areas in the ultraviolet image is weighted and summed according to the distance weight to obtain the final anti-noise degree.

7. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that: The method of selecting the optimal ultraviolet light image under the optimal filter according to the final anti-noise degree for leakage detection includes: Integrate the corona discharge spectrum function in each wavelength range to obtain the response characteristics of each filter, and take the product of the response characteristics and the final anti-noise degree as the optimization degree; select the optimal filter according to the optimization degree.

8. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 7, characterized in that: The filter with the highest preference is selected as the optimal filter.

9. A highly sensitive leakage insulation detection method for a switch cabinet according to claim 1, characterized in that: The leakage detection method comprises: The ultraviolet light image under the optimal filter is threshold segmented to obtain a highlight area, and the pixels in the highlight area are abnormal photon pixels; if the number of the abnormal photon pixels is greater than the preset number threshold, a leakage warning is fed back.

10. A highly sensitive leakage insulation detection device for a switch cabinet, characterized in that: The device includes a filter switching module, an ultraviolet sensor and a data processing module; the filter switching module includes a plurality of filter lenses with different wavelength ranges, and the ultraviolet sensor is used to receive signals after the filter lenses filter ultraviolet rays; the data processing module is used to execute a high-sensitivity leakage insulation detection method for a switch cabinet as described in any one of claims 1-9.

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