Device and method for visual detection of surface discharge ionization area

Abstract

The present invention provides a device and method for visually detecting the surface discharge ionization region, relating to the field of high-voltage discharge ionization measurement technology. The device includes a closed cavity, a ground electrode, a high-voltage electrode, a heating tape, an infrared camera, a computer, a detection impedance, an amplifier, and an oscilloscope. The heating tape is wrapped around the ground electrode and is used to heat the insulator through the ground electrode. The high-voltage electrode is used to apply voltage to the insulator and stimulate defect discharge on the insulator to ionize the insulating gas and form a gas ionization region. An observation window is provided on the side wall of the closed cavity. The infrared camera is disposed outside the closed cavity and facing the observation window. The infrared camera is used to photograph the gas ionization region and display the captured temperature distribution image on the computer. The detection impedance is used to measure the amount of local discharge and display it on the oscilloscope after amplification. The device and method can visualize the surface discharge ionization region of defective insulators and achieve online dynamic observation.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage discharge ionization measurement, and in particular to a device and method for visually detecting a surface discharge ionization area. Background Art

[0002] Gas-insulated switchgear (GIS) is a modular, metal-enclosed switchgear. It features a compact structure, small footprint, high reliability, strong safety, strong environmental adaptability, and minimal maintenance. It is widely used in power systems. Surface flashover caused by insulator failure is considered a major cause of faults.

[0003] Defects on the surface of insulators can lead to local electric field concentrations, inducing partial discharges. Insulation surface discharge is a major cause of GIS / GIL insulation failure, and studying the development process and mechanism of surface discharge is of great significance. However, the current research on the development process of surface discharge is mainly based on partial discharge measurements, lacking a direct and effective means of observing the discharge ionization region. Traditional infrared or ultraviolet observation methods measure the infrared or ultraviolet radiation generated by the gas discharge ionization itself, and only when the discharge is more intense can a clear infrared or ultraviolet image be measured. For the relatively weak discharges in the early stages of discharge development, there is still a lack of a more direct observation method to study the discharge ionization region and development process. Summary of the Invention

[0004] The purpose of the present invention includes providing a device and method for visualizing the surface discharge ionization region, which can realize visualization of the surface discharge ionization region of a defective insulator and realize online dynamic observation of the surface discharge ionization region.

[0005] The embodiments of the present invention can be implemented as follows:

[0006] In a first aspect, the present invention provides a device for visually detecting a surface discharge ionization region, the device comprising a closed cavity, a ground electrode, a high-voltage electrode, a heating belt, an infrared camera, a computer, a detection impedance, an amplifier, and an oscilloscope;

[0007] The ground electrode and the high-voltage electrode are arranged in a closed cavity with a gap between them. The space between the ground electrode and the high-voltage electrode is used to place the insulator with defects. The heating belt is wrapped on the ground electrode and is used to heat the insulator through the ground electrode. The closed cavity is used to be filled with insulating gas. The high-voltage electrode is used to apply voltage to the insulator and stimulate discharge of defects on the insulator to ionize the insulating gas and form a gas ionization area.

[0008] The ground electrode, detection impedance, amplifier and oscilloscope are connected in sequence. An observation window is provided on the side wall of the closed cavity. The infrared camera is provided outside the closed cavity and facing the observation window. The infrared camera is connected to a computer. The infrared camera is used to photograph the gas ionization area and display the photographed temperature distribution image on the computer. The detection impedance is used to measure the amount of partial discharge, which is amplified by the amplifier and displayed on the oscilloscope.

[0009] In an optional embodiment, the device further comprises a thermocouple and a temperature control unit, wherein the thermocouple is mounted on the heating belt, and the thermocouple and the heating belt are connected to the temperature control unit, and the temperature control unit is used to control the temperature of the heating belt.

[0010] In an optional embodiment, the infrared camera is further configured to perform correction according to the actual temperature of the insulator surface detected by the thermocouple.

[0011] In an optional embodiment, the observation window is made of germanium glass, and the insulating gas filled into the closed cavity is sulfur hexafluoride gas or nitrogen gas.

[0012] In a second aspect, the present invention provides a method for visually detecting a creeping discharge ionization region, which adopts the device for visually detecting a creeping discharge ionization region of the aforementioned embodiment.

[0013] In an alternative embodiment, the method comprises:

[0014] S1: Use a heating tape to heat the insulator through the ground electrode until the surface temperature of the insulator stabilizes;

[0015] S2: Using a high-voltage electrode to apply voltage to the insulator, stimulate defect discharge on the insulator to ionize the insulating gas and form a gas ionization region;

[0016] S3: Use an infrared camera to photograph the gas ionization area and display the photographed temperature distribution image on a computer.

[0017] In an optional embodiment, the method further comprises:

[0018] S4: According to the temperature distribution images obtained at different times, the temperature change area and the temperature change degree are obtained, and then the discharge ionization area and the discharge ionization degree are obtained.

[0019] In an optional embodiment, S4 includes:

[0020] S41: Calculating the temperature value of each position based on the temperature distribution images obtained at different times;

[0021] S42: subtracting the temperature values ​​at corresponding positions in the image to obtain the temperature change area and the degree of temperature change under different conditions, and then obtaining the discharge ionization area and the discharge ionization degree.

[0022] In an optional embodiment, S42 includes:

[0023] If △T ij =T0 ij -T1 ij >0, it is determined that discharge ionization occurs at the pixel position of row i and column j in the image, where T0 ij T1 is the temperature of the pixel at row i and column j in the image before voltage is applied and when the temperature is stable; ij is the temperature of the pixel at row i and column j in the image after voltage is applied to cause discharge ionization.

[0024] In an optional embodiment, S42 further includes:

[0025] If △T ij >△T ji , it is determined that the discharge ionization degree of the pixel position in the i-th row and j-th column in the image is greater than the discharge ionization degree of the pixel position in the j-th row and i-th column in the image.

[0026] The advantageous effects of the device and method for visually detecting the surface discharge ionization region provided by the embodiments of the present invention include:

[0027] By measuring the surface temperature of the insulator using infrared, the size of the discharge ionization region can be determined based on the size of the temperature reduction area in the temperature distribution image. The degree of discharge ionization can be determined based on the amplitude of the temperature reduction in the temperature reduction area in the temperature distribution image. This allows for visualization of the surface discharge ionization region and online dynamic observation of the surface discharge ionization region. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A schematic structural diagram of a device for visually detecting a surface discharge ionization region according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the surface temperature distribution of one end of the insulator when heated;

[0031] Figure 3 Schematic diagram of surface temperature distribution of the insulator due to surface discharge;

[0032] Figure 4A flow chart of a method for visually detecting a surface discharge ionization region provided by an embodiment of the present invention;

[0033] Figure 5 is the temperature distribution on the surface of the insulator before and after pressurization;

[0034] Figure 6 It is an evaluation of the discharge ionization area based on the apparent temperature difference on the insulator surface.

[0035] Icons: 100-surface discharge ionization area visualization detection device; 200-insulator; 1-enclosed cavity; 2-ground electrode; 3-high-voltage electrode; 4-heating belt; 5-thermocouple; 6-temperature control unit; 7-detection impedance; 8-amplifier; 9-oscilloscope; 10-infrared camera; 11-computer; 12-observation window; 13-defect. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0039] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as a limitation on the present invention.

[0040] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0041] Please refer to Figure 1This embodiment provides a device 100 for visually detecting a surface discharge ionization region (hereinafter referred to as the device). The device includes a closed cavity 1, a ground electrode 2, a high-voltage electrode 3, a heating belt 4, an infrared camera 10, a computer 11, a detection impedance 7, an amplifier 8, an oscilloscope 9, a thermocouple 5, and a temperature control unit 6.

[0042] Specifically, the ground electrode 2 and the high-voltage electrode 3 are spaced apart in the closed cavity 1 , the space between the ground electrode 2 and the high-voltage electrode 3 is used to place the insulator 200 with defects 13 , and the heating belt 4 is wrapped on the ground electrode 2 .

[0043] The heating belt 4 is used to heat the insulator 200 through the ground electrode 2. The closed cavity 1 is used to be filled with insulating gas. The insulating gas filled in the closed cavity 1 is sulfur hexafluoride gas or nitrogen gas.

[0044] The high voltage electrode 3 is used to apply voltage to the insulator 200 and stimulate the defects 13 on the insulator 200 to discharge, so as to ionize the insulating gas and form a gas ionization region.

[0045] The ground electrode 2 , the detection impedance 7 , the amplifier 8 and the oscilloscope 9 are connected in sequence. The detection impedance 7 is used to measure the amount of partial discharge, which is amplified by the amplifier 8 and then displayed on the oscilloscope 9 .

[0046] A thermocouple 5 is mounted on the heating belt 4. The thermocouple 5 and the heating belt 4 are connected to a temperature control unit 6. The thermocouple 5 can provide real-time feedback of the temperature of the heating belt 4 to the temperature control unit 6. The temperature control unit 6 is used to control the temperature of the heating belt 4. Specifically, when the temperature of the heating belt 4 exceeds the set temperature by 1°C, the temperature control unit 6 disconnects the heating power supply to the heating belt 4; when the temperature of the heating belt 4 falls below the set temperature by 1°C, the temperature control unit 6 controls the heating power supply to the heating belt 4 to be connected. The heating belt 4 is wrapped around the ground electrode 2 at one end of the insulator 200. The temperature control unit 6 allows for accurate control of the temperature of the heating belt 4, with a temperature control accuracy of ±1°C.

[0047] An observation window 12 is provided on the side wall of the closed cavity 1, and an infrared camera 10 is provided outside the closed cavity 1 and facing the observation window 12. The infrared camera 10 is connected to a computer 11. The infrared camera 10 is used to photograph the gas ionization area and display the photographed temperature distribution image on the computer 11.

[0048] The infrared camera 10 can be used to measure the surface temperature of the insulator 200 in real time. Specifically, a FLIRP630 infrared thermal imager can be used, with a detector wavelength range of 7.5-13 μm, a temperature measurement range of -40-+500°C, and a thermal sensitivity of 0.055°C.

[0049] The observation window 12 is made of germanium glass, which has good transmittance in the 1.7 μm to 16 μm band and can fully ensure infrared transmittance.

[0050] The infrared camera 10 is also used to perform corrections based on the actual surface temperature of the insulator 200 detected by the thermocouple 5. Specifically, to ensure the accuracy of the temperature measurement by the infrared camera 10, the temperature measurement results of the infrared camera 10 are corrected using the thermocouple 5 before measurement. The process is as follows: the infrared camera 10 is fixed at the shooting position, and the parameters such as the measurement distance, window transmittance, reflection temperature, ambient temperature and humidity of the infrared camera 10 are set according to actual conditions; the insulator 200 is heated, and after the temperature stabilizes, the actual surface temperature of the insulator 200 is measured using the thermocouple; the parameters such as the emissivity of the infrared camera 10 are adjusted to correct the temperature measurement results of the infrared camera 10 so that the measurement results of the infrared camera 10 are consistent with the measurement results of the thermocouple 5, and the correction is completed.

[0051] During measurement, the enclosed chamber 1 can be filled with 0.1-0.4 MPa of sulfur hexafluoride gas, nitrogen, or other gases. In this embodiment, the enclosed chamber 1 is filled with 0.4 MPa of pure, dry SF6 gas. In the SF6 gas, surface discharge across the insulator 200 ionizes neutral SF6 molecules, generating charged particles (including electrons, negative ions, and positive ions), forming a localized plasma. Neutral SF6 molecules and the plasma formed after ionization have different infrared absorption rates, which is exploited to visualize the discharge ionization region in the SF6 gas.

[0052] like Figure 2 As shown, one end of the insulator 200 is heated, and the surface temperature is distributed in a gradient from top to bottom. The infrared intensity radiated by the insulator 200 decreases continuously and evenly from top to bottom. Figure 3 As shown, if creeping discharge occurs in insulator 200, a discharge ionization region is generated. At this time, because the plasma formed by the ionized SF6 gas absorbs infrared rays more strongly than neutral SF6 molecules, a region of apparent temperature reduction corresponding to the discharge ionization region is formed on the temperature distribution image measured by infrared camera 10. This region of apparent temperature reduction corresponds to the region where the gas ionizes, thereby enabling visualization of the creeping discharge ionization region. As the creeping discharge progresses and becomes more intense, the number of charged particles in the discharge ionization region increases, and the ionization region's absorption of infrared rays becomes stronger. The region of temperature reduction on the temperature distribution image expands, and the degree of apparent temperature reduction increases, thereby enabling online visualization of the discharge ionization region.

[0053] See also Figure 4This embodiment also provides a method for visually detecting a surface discharge ionization region (hereinafter referred to as the method), which uses a device 100 for visually detecting a surface discharge ionization region. The method includes the following steps:

[0054] S1: The insulator 200 is heated by the heating belt 4 through the ground electrode 2 until the surface temperature of the insulator 200 stabilizes.

[0055] Specifically, when measuring the creeping discharge ionization region, the insulator 200 is heated, and the temperature is simultaneously monitored using the infrared camera 10 until the surface temperature of the insulator 200 is stable.

[0056] S2: applying voltage to the insulator 200 using the high voltage electrode 3 to stimulate discharge in the defects 13 on the insulator 200, thereby ionizing the insulating gas and forming a gas ionization region.

[0057] S3 : Using the infrared camera 10 to photograph the gas ionization region, and displaying the photographed temperature distribution image on the computer 11 .

[0058] S4: According to the temperature distribution images obtained at different times, the temperature change area and the temperature change degree are obtained, and then the discharge ionization area and the discharge ionization degree are obtained.

[0059] Specifically, voltage is applied to insulator 200 via high-voltage electrode 3 to stimulate discharge at defect 13. When there is no creeping discharge, the temperature distribution image clearly shows that, except for the discharge defect 13 itself, the temperature distribution in the remaining areas of the surface of insulator 200 exhibits a continuous and uniform change from top to bottom. When voltage is applied to insulator 200 to stimulate creeping discharge, ionization occurs in the localized area, and regions with a significant decrease in apparent temperature begin to appear in the temperature distribution image. These correspond to gas ionization regions generated by creeping discharge. As the voltage increases, the creeping discharge becomes more intense, and the corresponding regions of decreased apparent temperature in the temperature distribution image expand, indicating that the discharge ionization region is also expanding. Simultaneously, the magnitude of the temperature decrease in the corresponding region in the temperature distribution image also increases, indicating an increase in the number of charged particles generated by ionization and an intensification of the discharge ionization level.

[0060] Among them, S4 specifically includes:

[0061] S41: Calculating the temperature value of each position based on the temperature distribution images obtained at different times;

[0062] S42: subtracting the temperature values ​​at corresponding positions in the image to obtain the temperature change area and the degree of temperature change under different conditions, and then obtaining the discharge ionization area and the discharge ionization degree.

[0063] Specifically, the temperature of each position is calculated from the temperature distribution images obtained at different times, the temperature distribution measured during the pressurization process is compared with the temperature distribution when no voltage is applied, and the temperature values ​​of corresponding positions in the image are subtracted to obtain the area of ​​temperature change and the degree of temperature change under different conditions, thereby obtaining the discharge ionization area and ionization degree.

[0064] Specifically, before voltage is applied and the temperature is stable, the temperature of the pixel at row i and column j in the image is T0 ij ; After the voltage is applied to cause discharge ionization, the temperature of the pixel at the i-th row and j-th column in the image is T1 ij .

[0065] In the area where discharge ionization does not occur, the temperature change corresponding to all positions in the area is close to zero. On the contrary, the apparent temperature measured in the area where discharge ionization occurs will decrease. Therefore, if △T ij =T0 ij -T1 ij >0, it is determined that discharge ionization occurs at the pixel position in the i-th row and j-th column in the image.

[0066] If △T ij >△T ji , then the discharge ionization degree at the pixel position in the i-th row and j-th column of the image is determined to be greater than the discharge ionization degree at the pixel position in the j-th row and i-th column of the image. In other words, the magnitude of ΔT can also be used to determine the degree of discharge ionization. A larger ΔT indicates a more intense discharge ionization.

[0067] Figure 5 Figure 2 shows the temperature distribution along the axial direction of defect 13 on the surface of insulator 200 before and after discharge ionization. It can be seen that before discharge, the temperature along the surface of insulator 200 decreases continuously and evenly. After ionization, the temperature measured in the local area decreases significantly, indicating that significant ionization has occurred in this area.

[0068] Figure 6 The temperature variation ΔT of the insulator 200 surface defect 13 in the axial direction is given ij It can be seen that by calculating the difference in temperature values ​​measured before and after discharge at the same location, the size of the discharge ionization area and the degree of ionization can be evaluated.

[0069] The advantageous effects of the device 100 and method for visually detecting the surface discharge ionization region provided in this embodiment include:

[0070] By measuring the surface temperature of the insulator 200 by infrared, the size of the discharge ionization region can be determined based on the size of the temperature reduction area in the temperature distribution image, and the degree of discharge ionization can be determined based on the amplitude of the temperature reduction in the temperature reduction area in the temperature distribution image. This allows for visualization of the surface discharge ionization region and online dynamic observation of the surface discharge ionization region.

[0071] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for visually detecting a surface discharge ionization region, characterized in that: The method adopts a surface discharge ionization region visualization detection device, which includes a closed cavity (1), a ground electrode (2), a high-voltage electrode (3), a heating belt (4), an infrared camera (10), a computer (11), a detection impedance (7), an amplifier (8), an oscilloscope (9), a thermocouple (5) and a temperature control unit (6); The ground electrode (2) and the high-voltage electrode (3) are arranged in the closed cavity (1) at intervals, the space between the ground electrode (2) and the high-voltage electrode (3) is used to place the insulator (200) with the defect (13), the heating belt (4) is coated on the ground electrode (2), the heating belt (4) is used to heat the insulator (200) through the ground electrode (2), the closed cavity (1) is used to be filled with insulating gas, and the high-voltage electrode (3) is used to apply voltage to the insulator (200) and stimulate the defect (13) on the insulator (200) to discharge, so as to ionize the insulating gas and form a gas ionization region; The ground electrode (2), the detection impedance (7), the amplifier (8) and the oscilloscope (9) are connected in sequence. An observation window (12) is provided on the side wall of the closed cavity (1). The infrared camera (10) is provided outside the closed cavity (1) and faces the observation window (12). The infrared camera (10) is connected to the computer (11). The infrared camera (10) is used to photograph the gas ionization area and display the photographed temperature distribution image on the computer (11). The detection impedance (7) is used to measure the amount of partial discharge and is displayed on the oscilloscope (9) after being amplified by the amplifier (8). The thermocouple (5) is installed on the heating belt (4). The thermocouple (5) and the heating belt (4) are connected to the temperature control unit (6). The temperature control unit (6) is used to control the temperature of the heating belt (4). The method comprises: S1: using the heating belt (4) to heat the insulator (200) through the ground electrode (2) until the surface temperature of the insulator (200) is stable; S2: applying a voltage to the insulator (200) using the high-voltage electrode (3) to stimulate discharge at defects (13) on the insulator (200), thereby ionizing the insulating gas and forming a gas ionization region; S3: photographing the gas ionization area using the infrared camera (10), and displaying the photographed temperature distribution image on the computer (11); S4: According to the temperature distribution images obtained at different times, the temperature change area and the temperature change degree are obtained, and then the discharge ionization area and the discharge ionization degree are obtained.

2. The method for visually detecting the surface discharge ionization region according to claim 1, wherein S4 include: S41: Calculating the temperature value of each position based on the temperature distribution images obtained at different times; S42: subtracting the temperature values ​​at corresponding positions in the image to obtain the temperature change area and the degree of temperature change under different conditions, and then obtaining the discharge ionization area and the discharge ionization degree.

3. The method for visually detecting the surface discharge ionization region according to claim 2, characterized in that: S42 includes: If △T ij =T0 ij -T1 ij >0, it is determined that discharge ionization occurs at the pixel position of row i and column j in the image, where T0 ij T1 is the temperature of the pixel at row i and column j in the image before voltage is applied and when the temperature is stable; ij is the temperature of the pixel at row i and column j in the image after voltage is applied to cause discharge ionization.

4. The method for visually detecting the surface discharge ionization region according to claim 3, characterized in that: The S42 also includes: If △T ij >△T ji , it is determined that the discharge ionization degree of the pixel position in the i-th row and j-th column in the image is greater than the discharge ionization degree of the pixel position in the j-th row and i-th column in the image.

5. The method for visually detecting the surface discharge ionization region according to claim 1, characterized in that: The infrared camera (10) is also used to perform correction according to the actual temperature of the surface of the insulator (200) detected by the thermocouple (5).

6. The method for visually detecting the surface discharge ionization region according to claim 1, characterized in that: The observation window (12) is made of germanium glass, and the insulating gas filled into the closed cavity (1) is sulfur hexafluoride gas or nitrogen gas.

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