Method, system and equipment for detecting leakproofness of gas insulated switchgear and medium

Abstract

The invention discloses a method, a system, equipment and a medium for detecting the leakproofness of gas insulated switchgear, and the method comprises the steps: adding helium into clean and dry air in GIS equipment, and then measuring the concentration of the helium in an environmental region of the GIS equipment under the normal operation of the GIS equipment to obtain the concentration V0 of the helium under the normal operation of the GIS equipment; detecting the environmental helium concentration of the to-be-detected area of the GIS equipment to obtain the detected concentration, comparing the detected concentration with the concentration V0, determining a helium leakage area, continuing to detect the leakage area, and determining a local position area of helium leakage; obtaining a helium leakage point in the local position area through a schlieren imaging technology; the leakage rate of the leakage point is obtained through a standard leakage hole comparison method or a wrapping method; and calculating the leakage rate of the leakage point according to the internal and external air pressure difference. Therefore, the problems of low efficiency, poor accuracy and poor reliability of the existing GIS switch equipment gas leakage detection technology are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas insulated switchgear detection, and in particular to a method, system, equipment and medium for detecting the airtightness of a gas insulated switchgear. Background Art

[0002] With the rapid development of power systems, gas insulated switch gear (GIS) is widely used in power transmission and distribution networks due to its excellent insulation performance and compact design. GIS equipment is filled with SF6 gas, which has excellent insulation properties but is also a strong greenhouse gas. Therefore, monitoring the airtightness of GIS equipment and ensuring that environmentally friendly gas does not leak is crucial to equipment stability and safe operation of the power system.

[0003] Although the existing GIS equipment gas leak detection technology can detect gas leaks to a certain extent, it still has some limitations and disadvantages. First, traditional leak detection methods such as soap water leak test and local bandaging leak detection are cumbersome and inefficient, and it is difficult to adapt to the modern power system's demand for fast and accurate detection. Secondly, although the quantitative leak detection method can provide the leakage volume and annual leakage rate, the operation is complicated and time-consuming, which is not conducive to timely discovery and treatment of leakage problems. In addition, the existing technology is mainly aimed at SF6 gas leak detection. SF6 itself is a heavier gas that is obviously different from the environment (air). It is easy to measure it through infrared imaging or gas density relays. Now there are also more mature testing methods. However, for the dry clean air filled in the green GIS, the above detection method will basically be ineffective. Therefore, in order to improve the accuracy, efficiency and reliability of leak detection, it is urgent to find a gas leak detection method suitable for green GIS switch equipment. Summary of the invention

[0004] The present invention provides a method, system, device and medium for detecting the airtightness of a gas insulated switchgear, which are used to solve the problems of low efficiency, poor accuracy and poor reliability of the existing gas leakage detection technology for GIS switchgear.

[0005] In view of this, a first aspect of the present application provides a method for detecting the airtightness of a gas insulated switchgear, the method comprising:

[0006] After adding helium to the clean dry air in the GIS equipment, the concentration of the helium in the GIS equipment environment area is measured under normal operation of the GIS equipment to obtain the concentration V0 of the helium under normal operation of the GIS equipment;

[0007] Detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and compare it with the concentration V0 to determine the leakage area of ​​the helium, continue to detect the leakage area, and determine the local location area of ​​the helium leakage;

[0008] In the local area, obtaining the helium leakage point by using Schlieren imaging technology;

[0009] The leakage rate of the leakage point is obtained by a standard leak hole comparison method or a wrapping method; and the internal and external air pressure difference of the leakage point is obtained, and the leakage rate of the leakage point is calculated according to the internal and external air pressure difference.

[0010] Optionally, the environmental helium concentration of the area to be detected of the GIS equipment is detected to obtain a detected concentration and compared with the concentration V0 to determine the leakage area of ​​the helium, and the leakage area is continuously detected to determine the local location area of ​​the helium leakage, including:

[0011] The ambient helium concentration in the area to be detected by the GIS equipment is detected to obtain the detection concentration;

[0012] When the detected concentration is greater than the concentration V0 and greater than a preset threshold, the area to be detected is determined to be a leakage area of ​​the helium;

[0013] Continue to detect each local area in the leakage area to obtain the detection concentration of each local area, and use the local area corresponding to the maximum value in each detection concentration as the local position area of ​​the helium leakage.

[0014] Optionally, the obtaining of the internal and external air pressure difference of the leakage point and calculating the leakage rate of the leakage point according to the internal and external air pressure difference includes:

[0015] Based on the leakage rate calculation formula, the leakage rate of the leakage point is calculated according to the internal and external air pressure difference of the leakage point;

[0016] Wherein, the leakage rate calculation formula is:

[0017] ;

[0018] In the formula, is the leakage rate, is the ambient air pressure at the leak point, The internal and external pressure difference of the leakage point, It is the clean air pressure inside the GIS equipment.

[0019] Optionally, obtaining the helium leakage point in the local position area by using Schlieren imaging technology includes:

[0020] After the Schlieren imaging device is set up, the Schlieren imaging technology is used to obtain the leakage point of the helium gas, thereby obtaining the accurate location of the gas leakage of the GIS equipment;

[0021] Wherein, the setting method of the schlieren imaging device includes:

[0022] A concave mirror background plate is arranged in the local position area, and a point light source is arranged so as to completely cover the background plate; a camera is arranged according to the distance from the background plate so that the light beam emitted by the point light source is completely projected into the camera with the same size after being reflected by the background plate; a shading sheet is arranged in front of the lens of the camera, wherein the shading sheet is at a position to shield half of the light spot of the point light source.

[0023] A second aspect of the present application provides a gas insulated switchgear airtightness detection system, the device comprising:

[0024] The first detection unit is used to add helium into the clean dry air in the GIS device, and then measure the concentration of the helium in the environment area of ​​the GIS device under normal operation of the GIS device to obtain the concentration V0 of the helium under normal operation of the GIS device;

[0025] The second detection unit is used to detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and compare it with the concentration V0 to determine the leakage area of ​​the helium, continue to detect the leakage area, and determine the local location area of ​​the helium leakage;

[0026] An acquisition unit, used for acquiring the helium leakage point in the local position area by using the Schlieren imaging technology;

[0027] The calculation unit is used to obtain the leakage rate of the leakage point through the standard leak hole comparison method or the wrapping method; and obtain the internal and external air pressure difference of the leakage point, and calculate the leakage rate of the leakage point according to the internal and external air pressure difference.

[0028] Optionally, the second detection unit is specifically used to:

[0029] The ambient helium concentration in the area to be detected by the GIS equipment is detected to obtain the detection concentration;

[0030] When the detected concentration is greater than the concentration V0 and greater than a preset threshold, the area to be detected is determined to be a leakage area of ​​the helium;

[0031] Continue to detect each local area in the leakage area to obtain the detection concentration of each local area, and use the local area corresponding to the maximum value in each detection concentration as the local position area of ​​the helium leakage.

[0032] Optionally, obtaining the internal and external air pressure difference of the leakage point and calculating the leakage rate of the leakage point according to the internal and external air pressure difference specifically includes:

[0033] Based on the leakage rate calculation formula, the leakage rate of the leakage point is calculated according to the internal and external air pressure difference of the leakage point;

[0034] Wherein, the leakage rate calculation formula is:

[0035] ;

[0036] In the formula, is the leakage rate, is the ambient air pressure at the leak point, The internal and external pressure difference of the leakage point, It is the clean air pressure inside the GIS equipment.

[0037] Optionally, the acquisition unit is specifically used to:

[0038] After the Schlieren imaging device is set up, the Schlieren imaging technology is used to obtain the leakage point of the helium gas, thereby obtaining the accurate location of the gas leakage of the GIS equipment;

[0039] Wherein, the setting method of the schlieren imaging device includes:

[0040] A concave mirror background plate is arranged in the local position area, and a point light source is arranged so as to completely cover the background plate; a camera is arranged according to the distance from the background plate so that the light beam emitted by the point light source is completely projected into the camera with the same size after being reflected by the background plate; a shading sheet is arranged in front of the lens of the camera, wherein the shading sheet is at a position to shield half of the light spot of the point light source.

[0041] A third aspect of the present invention provides a gas insulated switchgear airtightness detection device, the device comprising a processor and a memory:

[0042] The memory is used to store program code and transmit the program code to the processor;

[0043] The processor is used to execute the steps of the airtightness detection method of the gas insulated switchgear as described in the first aspect according to the instructions in the program code.

[0044] A fourth aspect of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, and the program codes are used to execute the airtightness detection method for gas-insulated switchgear described in the first aspect.

[0045] It can be seen from the above technical solutions that the present invention has the following advantages:

[0046] The gas insulated switchgear airtightness detection method of the present invention adopts helium as a tracer gas, and provides an efficient and accurate GIS equipment gas leak detection technology. Due to its unique physical properties, such as low density and high permeability, helium shows extremely high sensitivity and accuracy in leak detection. This detection technology can monitor the sealing state of GIS equipment in real time. Once a leak occurs, the system can quickly locate the leak point and issue a timely warning. Compared with the traditional SF6 gas leak detection method, the helium tracer method is not only easy to operate, but also environmentally friendly, avoiding the use of greenhouse gases and harmful gases, and reducing potential risks to the environment and personnel health. In addition, through the Schlieren method technology, the gas leakage of GIS equipment can be accurately obtained, and the leakage point can be accurately located, providing a strong guarantee for the safe operation of the power system. And this method does not rely on the chemical properties of the gas. It only needs to have a gas leakage process to obtain the imaging of the gas leakage through the Schlieren method. When the background plate is large enough, the precise location of the gas leak can be checked in a larger range. Thereby solving the problem that the existing GIS switchgear gas leak detection technology has low efficiency, poor accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0048] Figure 1 A schematic flow chart of a method for detecting the airtightness of a gas insulated switchgear provided in an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of the placement of the Schlieren imaging device provided in an embodiment of the present invention;

[0050] Figure 3 A schematic structural diagram of a gas insulated switchgear airtightness detection system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] See also Figure 1 , a method for detecting the airtightness of a gas insulated switchgear provided in an embodiment of the present invention comprises:

[0053] Step 101: After adding helium into the clean dry air in the GIS device, the concentration of helium in the GIS device environment area is measured when the GIS device is operating normally, so as to obtain the helium concentration V0 when the GIS device is operating normally.

[0054] It should be noted that, firstly, based on the characteristics of low density, low reactivity and high detection sensitivity of helium, 1% of the tracer gas helium is added to the clean dry air of the GIS equipment (the clean air pressure in the GIS equipment is P0=0.8MP24031657a). Since the concentration of 1% of the tracer gas helium is low and it is an inert gas, it will hardly affect the insulation performance of the GIS equipment. Even if a discharge failure occurs in the GIS equipment, no derivative substances related to it will be produced due to its chemical inertness. Furthermore, in addition to using helium as a tracer gas for gas leak detection in GIS equipment, technicians in this field can also use other tracers, such as carbon dioxide or gas mixtures, as tracers to detect leaks. This method may provide a sensitivity comparable to that of helium testing, but considering the requirements of digital green GIS, it should achieve zero greenhouse gas, so the leak detection effect may not be guaranteed. Moreover, this type of detection method often makes it difficult to determine the exact location of the gas leak.

[0055] Then, the helium concentration in the environmental area of ​​the GIS equipment under normal operating conditions is measured using a preferred portable helium leak detector (or helium mass spectrometer). The minimum measurement accuracy of the helium leak detector is 0.01%vol. The suction gun or blowing probe of the helium leak detector is used to scan the outside of the GIS equipment. When the probe is facing the leak hole, helium is sucked into the mass spectrometer chamber of the leak detector along with the surrounding air, thereby generating a leak indication to achieve the purpose of leak detection. The ambient helium concentration is calculated as V0. The helium concentration inside the GIS is artificially filled and can be directly calculated without measurement. The helium concentration inside the GIS equipment is calculated as V1. Both V0 and V1 are constants.

[0056] Step 102, detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain the detected concentration and compare it with the concentration V0 to determine the helium leakage area, continue to detect the leakage area, and determine the local location area of ​​the helium leakage.

[0057] In one embodiment, step 102 includes:

[0058] The ambient helium concentration in the area to be detected of the GIS equipment is detected to obtain the detection concentration; when the detection concentration is greater than the concentration V0 and greater than the preset threshold, the area to be detected is determined to be a helium leakage area; the local areas in the leakage area are continuously detected to obtain the detection concentration of each local area, and the local area corresponding to the maximum value in each detection concentration is used as the local location area of ​​the helium leakage.

[0059] It should be noted that the helium concentration of the environment in the area to be detected of the GIS equipment is measured to obtain the helium concentration V in the area to be detected. When V> V0 and reaches a certain threshold, it is determined that a gas leak occurs in the GIS equipment in the detection area. The position of the helium leak detector is changed until a smaller area with a maximum value is found, thereby determining the local location of the gas leak.

[0060] Step 103: In the local area, the helium leakage point is obtained by using Schlieren imaging technology.

[0061] In one embodiment, step 103 includes:

[0062] After setting up the Schlieren imaging device, the Schlieren imaging technology is used to obtain the leakage point of helium, thereby obtaining the accurate position of the gas leakage of the GIS equipment; wherein, the setting method of the Schlieren imaging device includes: arranging a concave mirror background plate in the local position area, and setting a point light source whose light source can completely cover the background plate; setting a camera according to the distance from the background plate, so that the light beam emitted by the point light source is completely projected into the camera after being reflected by the background plate; arranging a shading sheet in front of the camera lens, wherein the shading sheet is at a position that covers half of the light spot of the point light source, such as Figure 2 shown.

[0063] It should be noted that a concave mirror background plate is arranged in the local area of ​​gas leakage, and a point light source is arranged at a designated position to illuminate it, which can make the light source completely cover the entire background plate, and a CCD high-resolution camera is arranged at a designated position, which is located near twice the focal length of the background plate, that is, the light beam emitted by the point light source is completely projected into the camera after being reflected by the background plate; a shading sheet is arranged in front of the camera lens, and the shading sheet is in a position that just covers half of the light spot of the point light source. The accurate location of the gas leakage of the GIS equipment is obtained by using the Schlieren imaging technology. Specifically, by comparing the background photos collected at different times or different angles, the change of the air refractive index gradient in the area is detected, and the area of ​​air refractive index gradient change caused by gas leakage is identified to determine the location of the leakage point.

[0064] Step 104, obtain the leakage rate of the leakage point by using the standard leak hole comparison method or the wrapping method; obtain the internal and external air pressure difference of the leakage point, and calculate the leakage rate of the leakage point according to the internal and external air pressure difference.

[0065] In one embodiment, in step 104: obtaining the internal and external air pressure difference of the leakage point, and calculating the leakage rate of the leakage point according to the internal and external air pressure difference, including: calculating the leakage rate of the leakage point according to the internal and external air pressure difference of the leakage point based on the leakage rate calculation formula; wherein the leakage rate calculation formula is:

[0066] ;

[0067] In the formula, is the leakage rate, is the ambient pressure at the leak point, The pressure difference between inside and outside the leak point, It is the clean air pressure inside the GIS equipment.

[0068] It should be noted that after the gas leakage point of the GIS equipment is determined, the leakage rate of the gas from the leak hole can be obtained by comparing with the standard leak hole, or the leak hole can be wrapped. In the initial state, the wrapped range is in a vacuum state, and then the wrapped gas pressure per unit time is measured to obtain the gas leakage rate of the GIS equipment. In addition, by reading the pressure difference between the inside and outside of the GIS equipment at that location, If the ambient air pressure at this time is P1, the absolute air pressure P inside the GIS equipment can be obtained, and compared with P0, the gas leakage rate can be obtained, and based on the gas leakage rate; further, those skilled in the art can also obtain the gas leakage time based on the leakage rate.

[0069] Gas leakage rate The calculation method is as follows:

[0070]

[0071] in:

[0072] The calculation method of gas leakage rate is as follows: Assuming that the area of ​​the standard leak hole is S0, the area of ​​the leak hole of the GIS device to be tested is S, and the gas pressure of the GIS device is P0, the gas leakage rate of the standard leak hole is v0, then the gas leakage rate v of the GIS device at this time is:

[0073]

[0074] The gas leakage rate can also be calculated by the following method. Assuming that the area around the leak hole is wrapped, The volume of the enclosed gas is M, then:

[0075] .

[0076] The present invention provides a method for detecting the airtightness of a gas insulated switchgear. The method uses tracer gas detection and schlieren imaging technology to detect the concentration of tracer gas in a detection area of ​​the GIS equipment to determine whether there is a possibility of gas leakage in the GIS equipment in the area. Thereafter, the schlieren imaging method is used to detect the change in the air refractive index gradient in the area by comparing background photos collected at different times or at different angles, identify the area of ​​air refractive index gradient change caused by gas leakage, and determine the location of the leakage point. Finally, the leakage rate of the leakage point is obtained through a standard leak hole comparison method or a wrapping method, and the leakage rate of the GIS equipment is estimated based on the pressure difference between the inside and outside of the GIS equipment.

[0077] The above is a method for detecting the airtightness of a gas insulated switchgear provided in an embodiment of the present invention. The following is a system for detecting the airtightness of a gas insulated switchgear provided in an embodiment of the present invention.

[0078] See also Figure 3 , a gas insulated switchgear airtightness detection system provided in an embodiment of the present invention comprises:

[0079] The first detection unit 201 is used to add helium into the clean dry air in the GIS device, and then measure the concentration of helium in the GIS device environment area under normal operation of the GIS device to obtain the helium concentration V0 under normal operation of the GIS device.

[0080] The second detection unit 202 is used to detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and compare it with the concentration V0 to determine the leakage area of ​​the helium, continue to detect the leakage area, and determine the local location area of ​​the helium leakage.

[0081] The acquisition unit 203 is used to acquire the helium leakage point in the local area by using the Schlieren imaging technology.

[0082] The calculation unit 204 is used to obtain the leakage rate of the leakage point by using the standard leak hole comparison method or the wrapping method; and obtain the internal and external air pressure difference of the leakage point, and calculate the leakage rate of the leakage point according to the internal and external air pressure difference.

[0083] Furthermore, an embodiment of the present invention also provides a gas insulated switchgear airtightness detection device, the device comprising a processor and a memory:

[0084] The memory is used to store program code and transmit the program code to the processor;

[0085] The processor is used to execute the steps of the method for detecting the airtightness of a gas insulated switchgear as described in the above method embodiment according to the instructions in the program code.

[0086] Furthermore, a computer-readable storage medium is provided in an embodiment of the present invention, and the computer-readable storage medium is used to store program codes, and the program codes are used to execute the airtightness detection method of the gas insulated switchgear described in the above method embodiment.

[0087] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0088] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0089] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0091] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the airtightness of a gas insulated switchgear, characterized in that: include: After adding helium to the clean dry air in the GIS equipment, the concentration of the helium in the GIS equipment environment area is measured under normal operation of the GIS equipment to obtain the concentration V0 of the helium under normal operation of the GIS equipment; Detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and compare it with the concentration V0 to determine the leakage area of ​​the helium, continue to detect the leakage area, and determine the local location area of ​​the helium leakage; In the local area, obtaining the helium leakage point by using Schlieren imaging technology; The leakage rate of the leakage point is obtained by a standard leak hole comparison method or a wrapping method; and the internal and external air pressure difference of the leakage point is obtained, and the leakage rate of the leakage point is calculated according to the internal and external air pressure difference.

2. The method for detecting the airtightness of a gas insulated switchgear according to claim 1, characterized in that: The method of detecting the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and comparing it with the concentration V0 to determine the leakage area of ​​the helium, and continuing to detect the leakage area to determine the local location area of ​​the helium leakage includes: The ambient helium concentration in the area to be detected by the GIS equipment is detected to obtain the detection concentration; When the detected concentration is greater than the concentration V0 and greater than a preset threshold, the area to be detected is determined to be a leakage area of ​​the helium; Continue to detect each local area in the leakage area to obtain the detection concentration of each local area, and use the local area corresponding to the maximum value in each detection concentration as the local position area of ​​the helium leakage.

3. The method for detecting the airtightness of a gas insulated switchgear according to claim 1, characterized in that: The step of obtaining the internal and external pressure difference of the leakage point and calculating the leakage rate of the leakage point according to the internal and external pressure difference comprises: Based on the leakage rate calculation formula, the leakage rate of the leakage point is calculated according to the internal and external air pressure difference of the leakage point; Wherein, the leakage rate calculation formula is: ； In the formula, is the leakage rate, is the ambient air pressure at the leak point, The internal and external pressure difference of the leakage point, It is the clean air pressure inside the GIS equipment.

4. The method for detecting the airtightness of a gas insulated switchgear according to claim 1, characterized in that: The obtaining of the helium leakage point in the local area by using the Schlieren imaging technology includes: After the Schlieren imaging device is set up, the Schlieren imaging technology is used to obtain the leakage point of the helium gas, thereby obtaining the accurate location of the gas leakage of the GIS equipment; Wherein, the setting method of the schlieren imaging device includes: A concave mirror background plate is arranged in the local position area, and a point light source is arranged so as to completely cover the background plate; a camera is arranged according to the distance from the background plate so that the light beam emitted by the point light source is completely projected into the camera with the same size after being reflected by the background plate; a shading sheet is arranged in front of the lens of the camera, wherein the shading sheet is at a position to shield half of the light spot of the point light source.

5. A gas-insulated switchgear airtightness detection system, characterized in that: include: The first detection unit is used to add helium into the clean dry air in the GIS device, and then measure the concentration of the helium in the environment area of ​​the GIS device under normal operation of the GIS device to obtain the concentration V0 of the helium under normal operation of the GIS device; The second detection unit is used to detect the ambient helium concentration in the area to be detected of the GIS equipment to obtain a detection concentration and compare it with the concentration V0 to determine the leakage area of ​​the helium, continue to detect the leakage area, and determine the local location area of ​​the helium leakage; An acquisition unit, used for acquiring the helium leakage point in the local position area by using the Schlieren imaging technology; The calculation unit is used to obtain the leakage rate of the leakage point through the standard leak hole comparison method or the wrapping method; and obtain the internal and external air pressure difference of the leakage point, and calculate the leakage rate of the leakage point according to the internal and external air pressure difference.

6. The airtightness detection system for gas insulated switchgear according to claim 5, characterized in that: The second detection unit is specifically used for: The ambient helium concentration in the area to be detected by the GIS equipment is detected to obtain the detection concentration; When the detected concentration is greater than the concentration V0 and greater than a preset threshold, the area to be detected is determined to be a leakage area of ​​the helium; Continue to detect each local area in the leakage area to obtain the detection concentration of each local area, and use the local area corresponding to the maximum value in each detection concentration as the local position area of ​​the helium leakage.

7. The airtightness detection system for gas insulated switchgear according to claim 5, characterized in that: The step of obtaining the internal and external pressure difference of the leakage point and calculating the leakage rate of the leakage point according to the internal and external pressure difference specifically includes: Based on the leakage rate calculation formula, the leakage rate of the leakage point is calculated according to the internal and external air pressure difference of the leakage point; Wherein, the leakage rate calculation formula is: ； In the formula, is the leakage rate, is the ambient air pressure at the leak point, The internal and external pressure difference of the leakage point, It is the clean air pressure inside the GIS equipment.

8. The airtightness detection system for gas insulated switchgear according to claim 5, characterized in that: The acquisition unit is specifically used for: After the Schlieren imaging device is set up, the Schlieren imaging technology is used to obtain the leakage point of the helium gas, thereby obtaining the accurate location of the gas leakage of the GIS equipment; Wherein, the setting method of the schlieren imaging device includes: A concave mirror background plate is arranged in the local position area, and a point light source is arranged so as to completely cover the background plate; a camera is arranged according to the distance from the background plate so that the light beam emitted by the point light source is completely projected into the camera with the same size after being reflected by the background plate; a shading sheet is arranged in front of the lens of the camera, wherein the shading sheet is at a position to shield half of the light spot of the point light source.

9. A gas-insulated switchgear airtightness detection device, characterized in that: The device comprises a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the airtightness detection method of the gas insulated switchgear according to any one of claims 1 to 4 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the airtightness detection method for gas-insulated switchgear according to any one of claims 1 to 4.

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