A method for analyzing the discharge fault of a hybrid insulating gas based on a detection platform

Abstract

The present invention discloses a method for analyzing the discharge fault of a hybrid insulating gas based on a detection platform. The platform includes: two insulating gas cylinders, a high-voltage generator, a gas chromatography-mass spectrometry (GC-MS) instrument, a spectrometer, and a discharge simulation cavity. A discharge electrode is arranged in the cavity. The method includes: evacuating the simulation cavity; filling the simulation cavity with a mixed gas of SF<subgt;6< / subgt; and N<subgt;2< / subgt> according to the actual application ratio and pressure; the high-voltage generator applies a stepped power-frequency alternating voltage to the discharge electrode, monitors whether a discharge signal appears in the simulation cavity during the duration of each pressurization gradient, and uses the gas chromatography-mass spectrometry instrument to sample and detect the mixed insulating gas after each pressurization gradient is completed; when a discharge signal appears in the simulation cavity, judge the degree of discharge: By fusing the characteristic signals of two different detection methods and complementing each other, the present invention improves the confidence level of capturing and identifying the partial discharge signals of electrical equipment.

Description

Technical Field

[0001] The present invention relates to a method for analyzing the discharge fault of a hybrid insulating gas based on a detection platform. Background Art

[0002] SF6 is the known optimal electrical insulating medium. However, it is also the industrial gas with the strongest greenhouse effect. Under the grand goal of "dual carbon", it is an inevitable choice to develop environmentally friendly alternative gases to SF6 and reduce the consumption of SF6 greenhouse gas. At present, the SF6 replacement technologies are mainly divided into two types. One is to use SF6 / N2 mixed gas, that is, adding 30% N2 to SF6 gas, which greatly reduces the consumption of greenhouse gas and has insulation performance equivalent to that of SF6. At the present stage, the SF6 / N2 mixed gas begins to be widely promoted and applied in GIS busbars within the domestic scope.

[0003] During the operation of electrical equipment, faults or defects will inevitably occur. Insulation defects are difficult to be detected during daily operation and maintenance, which often lead to serious consequences. According to statistics, between 2006 and 2015, the installation amount of gas-insulated switchgear (GIS) increased significantly, but there are more and more defects and faults, and the maintenance-free advantage of GIS cannot be reflected. The defects of gas-insulated equipment mainly include partial discharge defects and local overheating defects. According to the type of reasons, the number of discharges caused by foreign objects is the largest and the impact is the greatest. It is necessary to identify and diagnose the discharge defects of gas-insulated electrical equipment.

[0004] The partial discharge of insulation in electrical equipment mainly includes corona discharge, spark discharge, surface discharge, floating discharge, etc. Different discharge types have different fault signals and gas decomposition products. According to the physical and chemical phenomena such as electricity, magnetism, sound, light, and heat generated during the discharge, the common detection means are pulse current method, ultra-high frequency method, ultrasonic method, optical method, and decomposition gas method, etc. Among them, the optical method realizes discharge measurement by identifying the optical signals during the discharge process. The advantage is that it is not easily interfered by electrical signals, and the disadvantage is that it is difficult to quantify, and it is easily affected by factors such as the structure of electrical equipment and detection angle, resulting in detection blind areas and affecting the detection effect. The decomposition gas method, that is, by monitoring the types, contents and other characteristics of gas products generated by the chemical reaction of the insulating medium to judge the operation state of the equipment, has the advantages of no electromagnetic interference, no vibration noise and no invasiveness (no need to transform the existing equipment), but this method has a slow response and cannot reflect sudden faults in real time. Summary of the Invention

[0005] The object of the present invention is to propose a method for analyzing the discharge fault of a mixed insulating gas based on a detection platform. For SF6 / N2 mixed gas insulated equipment, there are many influencing factors for discharge, and it is difficult for a single detection technology to capture the fault signals of the equipment under test. The present invention proposes a method for capturing fault signals by combining an optical detection method and a decomposed gas method. By fusing the characteristic signals of the two different detection methods and complementing each other, the confidence level of capturing and identifying partial discharge signals of electrical equipment is improved.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for analyzing the discharge fault of a mixed insulating gas based on a detection platform, the detection platform includes: two insulating gas cylinders for storing SF6 and N2 insulating gases, a high-voltage generator, a gas chromatography-mass spectrometry (GC-MS) instrument and a spectrometer, a discharge simulation cavity, in which a discharge electrode is arranged, the wiring terminal of the discharge electrode is sealed and led out from the cavity shell and connected to an output terminal of the high-voltage generator, the other output terminal of the high-voltage generator is connected to the cavity shell, a gas introduction interface is arranged on the cavity shell, the gas introduction interface is connected to a gas main pipe, the output interfaces of the two insulating gas cylinders are respectively connected to the gas main pipe through gas output control valves, a vacuum pump is also connected to the gas main pipe through a vacuum extraction control valve, the GC-MS instrument is connected to the gas main pipe through a detection valve, an optical fiber probe is arranged on the cavity shell, and the optical fiber probe is connected to the spectrometer through an optical fiber; the steps of the discharge fault analysis method include:

[0008] One, evacuate the simulation cavity.

[0009] Two, fill the simulation cavity with SF6 and N2 mixed gas according to the actual application ratio and pressure.

[0010] Three, the high-voltage generator applies a stepped power-frequency alternating voltage to the discharge electrode, the spectrometer monitors whether there is a discharge signal in the simulation cavity during the duration of each pressure application gradient, and the GC-MS instrument is used to sample and detect the mixed insulating gas after each pressure application gradient is completed.

[0011] Four, when a discharge signal appears in the simulation cavity, judge the discharge degree:

[0012] a, use the GC-MS instrument to obtain SO2, SOF2 and SO2F2 gases by comparing with the standard gases in the standard mass spectrometry library. The SO2, SOF2 and SO2F2 gases are the decomposed gases generated during the discharge of the SF6 / N2 mixed gas, and calculate the content of each decomposed gas component according to formula 1;

[0013] C i =(S i / S I)×C I Formula 1

[0014] Where:

[0015] S i is the peak area corresponding to the characteristic mass-to-charge ratio of the insulating gas decomposition gas components,

[0016] S I is the peak area corresponding to the same characteristic mass-to-charge ratio of the standard gas of the component to be determined,

[0017] C I is the content of the standard gas of the component to be determined, C i is the content of the component to be determined;

[0018] When the partial discharge inception voltage decreases, since the relative content of SO2F2 will increase while the relative content of SO2 + SOF2 decreases; conversely, when the discharge degree deepens, the relative content of SO2 + SOF2 increases and the relative content of SO2F2 decreases; therefore, from a quantitative perspective, the ratio of (SO2 + SOF2) / SO2F2 is directly affected by the applied voltage and the local inception discharge voltage; according to Formula 2, the content ratio R of (SO2 + SOF2) / SO2F2 g is used as an index to reflect the discharge intensity;

[0019] R g = c[SO2 + SOF2] / c[SO2F2] Formula 2

[0020] Wherein, c[SO2 + SOF2] is the sum of the contents of SO2 and SOF2 gases; c[SO2F2] is the content of SO2F2;

[0021] b. Using a spectrometer, the maximum spectral intensity corresponding to the radiation transition of N2 gas appears at a wavelength of 336.9 nm to obtain the spectral intensity of N2 gas, the maximum spectral intensity corresponding to the radiation transition of NO gas appears at a wavelength of 239.7 nm to obtain the spectral intensity of NO gas, and the maximum spectral intensity corresponding to the radiation transition of nitrogen ion N + appears at a wavelength of 500.7 nm to obtain the spectral intensity of nitrogen ion N + The spectral intensity components at these 3 characteristic wavelengths are normalized according to Formula 3 and are respectively denoted as R1, R2, and R3, as an index for judging the discharge degree, that is, the spectral intensities at wavelengths of 336.9 nm, 239.7 nm, and 500.7 nm corresponding to the discharge stage and the total index of the three spectral intensities. If the proportion of R1 at 336.9 nm is the highest, the discharge is in the initial stage; if the proportion of R2 at 239.7 nm is the highest, the discharge is in the development stage; if the proportion of R3 at 500.7 nm is the highest, the discharge is already very severe;

[0022]

[0023] Wherein:

[0024] R i is the normalized value of the spectral intensity at the characteristic wavelength;

[0025] I i is the spectral intensity value at the characteristic wavelength;

[0026] c. According to the wavelength range of 200 - 380 nm for the ultraviolet band, 380 - 780 nm for the visible light band, and 780 - 980 nm for the near-infrared band, the ultraviolet wave, visible light wave, and near-infrared wave signals in the simulation cavity are obtained. The number of photons in each band is calculated using formula 4.

[0027]

[0028] By comparison: Since the number of photons in the ultraviolet band dominates in the early stage of discharge, and the number of photons in the visible light band dominates in the discharge development stage. As the degree of discharge defect deepens, within the range of 200 - 780 nm, the proportion of photons in the ultraviolet band gradually decreases, and the proportion of photons in the visible light band gradually increases, forming a clustering distribution to judge the degree of discharge defect.

[0029] d. Judgment: When the proportion of R3 at the wavelength of 500.7 nm is the highest, the proportion of photons in the visible light band is higher than that in the ultraviolet light band, and R g < 2, then the partial discharge is already very serious, and breakdown discharge may occur at any time, which should be noted and warned.

[0030] A further aspect of the solution is: After filling the SF6 and N2 mixed gas into the simulation cavity, it is placed at room temperature for at least 12 hours to fully mix the gas.

[0031] A further aspect of the solution is: The range of the applied power frequency alternating voltage is 0 - 40 kV, the voltage gradient is 2 kV, and the duration of each voltage application gradient is 15 minutes.

[0032] A further aspect of the solution is: Within the range of the applied power frequency alternating voltage of 0 - 40 kV, the method further includes: When the voltage is increased and discharge occurs until the discharge electrode breaks down with the housing, the high-voltage generator cuts off the power input through the built-in overcurrent protection action at the moment of breakdown and automatically reduces the voltage.

[0033] A further aspect of the solution is: A main control valve is provided in the gas main pipe. The main control valve is arranged between the gas inlet interface of the cavity housing and the gas output control valves and the vacuum extraction control valve of the two insulating gas cylinders. The detection valve is directly connected to the gas inlet interface of the cavity housing through the gas main pipe.

[0034] A further solution is: a transparent quartz glass observation window is provided on the cavity shell, and the optical fiber probe is provided on the observation window.

[0035] A further solution is that the simulation cavity is placed in a dark room, and a pressure gauge is provided on the simulation cavity for intuitively displaying the changes in the insulating gas pressure in the cavity.

[0036] A further solution is that the optical fiber probe is equipped with an optical focusing lens for collecting photoluminescence radiation generated by local discharge.

[0037] A further solution is that the optical focusing lens is an optical focusing lens that can see through light in the 200-900nm band.

[0038] A further solution is that the cavity can withstand at least 4 atmospheres of pressure.

[0039] The beneficial effect of the present invention is that: the present invention proposes a fault signal capture method that combines an optical detection method and a decomposition gas method, which improves the confidence of capturing and identifying partial discharge signals of electrical equipment by fusing the characteristic signals of the two different detection methods and complementing each other.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic structural diagram of the detection platform of the present invention;

[0042] Figure 2 Schematic diagram of emission spectrum detection and decoupling at different discharge stages of the present invention;

[0043] Figure 3 This is a schematic diagram of the discharge development degree identification based on the characteristic emission spectrum of the present invention;

[0044] Figure 4 This is a comparison diagram of the photon number integral and distribution in the ultraviolet-visible light band during the discharge development process of the present invention;

[0045] Figure 5 The standard mass spectra of SOF2, SO2 and SO2F2;

[0046] Figure 6 Schematic diagram of discharge severity identification based on the decomposition gas method of the present invention. DETAILED DESCRIPTION

[0047] A hybrid insulating gas discharge fault analysis method based on a detection platform, such as Figure 1As shown in the figure, the detection platform includes: two insulating gas cylinders, namely a gas cylinder 1 for storing SF6 insulating gas and a gas cylinder 2 for storing N2 insulating gas. The detection platform also includes a high-voltage generator 3, a gas chromatography-mass spectrometry (GC-MS) instrument 4, and a spectrometer 5. Among them: The high-voltage generator 3 has two working modes: (1) Output a power-frequency alternating voltage with a constant amplitude; (2) When the voltage is boosted and discharged until the discharge electrode breaks down with the object, the built-in current protection in the high-voltage generator acts instantaneously during breakdown, cuts off the power input, and automatically reduces the voltage. When working in mode (1), the setting range of the withstand voltage time is 1 - 600 s, and the amplitude of the output voltage can be adjusted between 1 - 100 kV. The input interface 401 of the gas chromatography-mass spectrometry (GC-MS) instrument 4 uses a gas chromatography six-port valve input interface. The detection platform also includes a discharge simulation cavity 6. The cavity is a cavity that can withstand at least 4 atmospheric pressures. A discharge electrode 7 is arranged in the cavity. The wiring terminal of the discharge electrode is sealed and led out from the cavity shell and connected to an output terminal (positive electrode) of the high-voltage generator 3. The other output terminal (negative electrode) of the high-voltage generator is connected to the cavity shell. A gas inlet interface 601 is arranged on the cavity shell. The gas inlet interface 601 is connected to a gas main pipe 8. The output interfaces of the two insulating gas cylinders are respectively connected to the gas main pipe 8 through gas output control valves 101 and 201. A vacuum pump 9 is also connected to the gas main pipe 8 through a vacuum extraction control valve 901. The vacuum pump 9 is used to evacuate the cavity. The gas chromatography-mass spectrometry (GC-MS) instrument 4 is connected to the gas main pipe 8 through a detection valve 10. An optical fiber probe 11 is arranged on the cavity shell. The optical fiber probe 11 is connected to the spectrometer 5 through an optical fiber 12; The optical fiber probe is equipped with an optical focusing lens. The optical focusing lens transmits light in the 200 - 900 nm band, which is also the detection range of the spectrometer, and is used to collect the optical radiation generated by partial discharge; The steps of the discharge fault analysis method include:

[0048] First, evacuate the simulation cavity.

[0049] Second, fill the simulation cavity with a mixed gas of SF6 and N2 according to the actual application ratio and pressure. After filling the simulation cavity with the mixed gas of SF6 and N2, place it at room temperature for at least 12 hours to fully mix the gas.

[0050] Third, the high-voltage generator applies a stepped power-frequency alternating voltage to the discharge electrode. The spectrometer monitors whether a discharge signal appears in the simulation cavity during the duration of each pressure step. The range of the applied power-frequency alternating voltage is 0 - 40 kV, the voltage step is 2 kV, and the duration of each pressure step is 15 minutes; After each pressure step is completed, use the gas chromatography-mass spectrometry (GC-MS) instrument to sample and detect the mixed insulating gas; During the discharge process, use the spectrometer to detect the emission spectrum formed by the energy level transition of particles such as molecules, atoms, and ions during the discharge process.

[0051] 4. When a discharge signal appears in the simulation cavity, judge the discharge degree:

[0052] a. Use a gas chromatography-mass spectrometry (GC-MS) instrument to obtain SO2, SOF2, and SO2F2 gases by comparing with standard gases in a standard mass spectrometry library. The SO2, SOF2, and SO2F2 gases are decomposition gases generated during the discharge of an SF6 / N2 mixed gas. Calculate the content of each decomposition gas component according to Formula 1;

[0053] C i =(S i / S I )×C I Formula 1

[0054] Where:

[0055] S i is the peak area corresponding to the characteristic mass-to-charge ratio of the decomposition gas components of the insulating gas,

[0056] S I is the peak area corresponding to the same characteristic mass-to-charge ratio of the standard gas of the component to be determined,

[0057] C I is the content of the standard gas of the component to be determined, and C i is the content of the component to be determined;

[0058] When the partial discharge inception voltage decreases, since the relative content of SO2F2 will increase while the relative content of SO2 + SOF2 decreases; conversely, when the discharge degree deepens, the relative content of SO2 + SOF2 increases and the relative content of SO2F2 decreases; therefore, from a quantitative perspective, the ratio of (SO2 + SOF2) / SO2F2 is directly affected by the applied voltage and the local inception discharge voltage; according to Formula 2, the content ratio R of (SO2 + SOF2) / SO2F2 g is used as an index to reflect the discharge intensity;

[0059] R g = c[SO2 + SOF2] / c[SO2F2] Formula 2

[0060] Where, c[SO2 + SOF2] is the sum of the contents of SO2 and SOF2 gases; c[SO2F2] is the content of SO2F2;

[0061] b. Such as Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6As shown; using a spectrometer, the maximum spectral intensity corresponding to the radiative transition of N2 gas in the early stage of discharge appears at a wavelength of 336.9 nm to obtain the spectral intensity of N2 gas, the maximum spectral intensity corresponding to the radiative transition of NO gas appears at a wavelength of 239.7 nm to obtain the spectral intensity of NO gas, and the maximum spectral intensity corresponding to the radiative transition of nitrogen ion N + appears at a wavelength of 500.7 nm to obtain the spectral intensity of nitrogen ion N + Perform normalization processing on the spectral intensity components at these 3 characteristic wavelengths according to formula 3, and denote them as R1, R2, and R3 respectively, as an index for judging the discharge degree, that is, the spectral intensities at wavelengths 336.9 nm, 239.7 nm, and 500.7 nm corresponding to the discharge stage and the total index of the spectral intensities of the three. If the proportion of R1 at 336.9 nm is the highest, the discharge is in the initial stage; if the proportion of R2 at 239.7 nm is the highest, the discharge is in the development stage; if the proportion of R3 at 500.7 nm is the highest, the discharge is already very serious;

[0062]

[0063] Where:

[0064] R i is the normalized value of the spectral intensity at the characteristic wavelength;

[0065] I i is the spectral intensity value at the characteristic wavelength;

[0066] c, According to the ultraviolet band is 200 - 380 nm, the visible light band is 380 - 780 nm, and the near-infrared band is 780 - 980 nm, obtain the ultraviolet wave, visible light wave, and near-infrared wave signals in the simulation cavity, and use formula 4 to calculate the number of photons in each band,

[0067]

[0068] By comparison: According to the dominance of the number of photons in the ultraviolet band in the early stage of discharge, the dominance of the number of photons in the visible light band in the development stage of discharge, and as the degree of discharge defects deepens, in the range of 200 - 780 nm, the photon ratio in the ultraviolet band gradually decreases, and the photon ratio in the visible light band gradually increases to form a clustering distribution to judge the degree of discharge defects;

[0069] d, Judgment: When the proportion of R3 at a wavelength of 500.7 nm is the highest, the photon ratio in the visible light band is higher than that in the ultraviolet light band, and R g < 2, then the partial discharge is already very serious and breakdown discharge may occur at any time, and attention should be paid and early warning should be given.

[0070] Among them: By comparing with the standard mass spectrometry library and standard gas, if the mass-to-charge ratio and relative abundance of the decomposition gas to be detected match the substances in the standard mass spectrometry library by 90% or more, and the retention time is the same as that of the configured standard gas, the type of the decomposition gas is determined to be the standard gas. Then, based on the relative abundance of the mass-to-charge ratio in the standard mass spectrometry library, characteristic mass-to-charge ratios are selected, and the contents of various decomposition products in the sample are analyzed based on the external standard quantitative method. SO2, SOF2, and SO2F2 are the main decomposition gases of the SF6 / N2 mixed gas. By comparing the standard mass spectrometry library and the standard gas, as Figure 5 shown, the abundances of SO2 are the highest at mass-to-charge ratios of 28 and 64, those of SOF2 are the highest at 67 and 86, and those of SO2F2 are the highest at 83 and 102. Therefore, the characteristic mass-to-charge ratios of SO2 are selected as 28 and 64, those of SOF2 are 67 and 86, and those of SO2F2 are 83 and 102. Based on the external standard quantitative method, the contents of various impurity components in the sample are obtained according to the chromatographic peak areas of the characteristic mass-to-charge ratios of different impurity gas components, the chromatographic peak areas of the characteristic mass-to-charge ratios of the corresponding standard gas, and the content of the standard gas.

[0071] Within the range of 0 - 40 kV of the applied power frequency alternating voltage, the method further includes: when the voltage is increased to cause breakdown between the discharge electrode and the housing, the high-voltage generator acts through the built-in current protection at the moment of breakdown, cuts off the power input, and automatically reduces the voltage.

[0072] Among them: For convenient control: a total control valve 13 is provided in the gas main pipe. The total control valve is arranged between the gas inlet interface 601 of the cavity housing and multiple gas output control valves 101, 201, and the vacuum extraction control valve 901. The detection valve 13 is directly connected to the gas inlet interface 601 of the cavity housing through the gas main pipe 8; to avoid interference of external light on the detection, the simulation cavity is placed in a dark room, and a pressure gauge 14 is also provided on the discharge simulation cavity 6 to visually display the change in the pressure of the insulating gas in the cavity 6.

[0073] For convenient observation: a transparent quartz glass observation window 15 is provided on the cavity housing, and the optical fiber probe 11 is arranged on the observation window; the lower cut-off wavelength of the transparent quartz glass is in the range of 180 - 210 nm, and it has good light transmittance in the wavelength band of 200 - 900 nm.

[0074] The above-mentioned embodiment of the method for analyzing the discharge fault of the mixed insulating gas based on the detection platform improves the confidence level of capturing and identifying the partial discharge signals of electrical equipment by fusing the characteristic signals of two different detection methods and complementing each other.

Claims

1. A method for analyzing the discharge fault of a hybrid insulating gas based on a detection platform, the detection platform comprising: Two insulating gas cylinders storing SF6 and N2 insulating gases, a high-voltage generator, a gas chromatograph-mass spectrometer and a spectrometer, and a discharge simulation cavity are provided. A discharge electrode is provided in the cavity. The discharge electrode terminal is sealed and led out from the cavity shell to connect to an output end of the high-voltage generator. The other output end of the high-voltage generator is connected to the cavity shell. A gas introduction interface is provided on the cavity shell. The gas introduction interface is connected to a gas main pipe. The output interfaces of the two insulating gas cylinders are respectively connected to the gas main pipe through gas output control valves. A vacuum pump is also connected to the gas main pipe through a vacuum extraction control valve. The gas main pipe is connected to the gas chromatograph-mass spectrometer through a detection valve. A fiber optic probe is provided on the cavity shell. The fiber optic probe is connected to the spectrometer through an optical fiber. The discharge fault analysis method comprises the following steps: First, vacuum the simulation cavity; Second, fill the simulation cavity with SF6 and N2 mixed gas according to the actual application ratio and pressure; Third, the high-voltage generator applies a power-frequency AC voltage to the discharge electrode in a stepped manner. The spectrometer monitors whether a discharge signal appears in the simulated cavity during the duration of each pressure gradient. After each pressure gradient is completed, the mixed insulating gas is sampled and tested using a gas chromatography-mass spectrometer. Fourth, when a discharge signal appears in the simulation cavity, determine the discharge degree: a. Using a gas chromatography-mass spectrometer, SO2, SOF2, and SO2F2 gases are obtained by comparing with standard gases in a standard mass spectrum library. The SO2, SOF2, and SO2F2 gases are decomposition gases generated during discharge of a SF6 / N2 mixed gas. The content of each decomposition gas component is calculated according to Formula 1. C i =(S i / S I )×C I Formula 1 in: S i is the peak area corresponding to the characteristic mass-to-charge ratio of the insulating gas decomposition gas components S I is the peak area corresponding to the same characteristic mass-to-charge ratio of the standard gas of the component to be determined, C I is the standard gas content of the component to be determined, C i is the content of the component to be determined; When the starting voltage of the power supply decreases, the relative content of SO2F2 will increase while the relative content of SO2 + SOF2 decreases; conversely, when the degree of discharge deepens, the relative content of SO2 + SOF2 increases and the relative content of SO2F2 decreases; therefore, quantitatively, the ratio of (SO2 + SOF2) / SO2F2 is directly affected by the applied voltage and the local starting discharge voltage; according to Equation 2, the content ratio of (SO2 + SOF2) / SO2F2 R g As an index reflecting the discharge intensity; R g = c[SO2 + SOF2] / c[SO2F2] Formula 2 Wherein, c[SO2+SOF2] is the sum of the contents of SO2 and SOF2 gases; c[SO2F2] is the content of SO2F2; b. Use a spectrometer to obtain the spectral intensity of N2 gas when the maximum spectral intensity of the radiation transition corresponding to N2 gas appears at a wavelength of 336.9 nm in the early stage of the discharge, obtain the spectral intensity of NO gas when the maximum spectral intensity of the radiation transition corresponding to NO gas appears at a wavelength of 239.7 nm, and obtain the spectral intensity of nitrogen ion N + when the maximum spectral intensity of the radiation transition appears at a wavelength of 500.7 nm. Normalize the spectral intensity components at these three characteristic wavelengths according to Equation 3, and denote them as + respectively. R 1 , R 2 and R 3 ， As an index for judging the discharge degree, that is, the spectral intensities at wavelengths 336.9 nm, 239.7 nm, and 500.7 nm corresponding to the discharge stage and the total index of the spectral intensities of the three. If the R 1 at 336.9 nm has the highest proportion, the discharge is in the initial stage; if the R 2 at 239.7 nm has the highest proportion, the discharge is in the development stage; if the R 3 at 500.7 nm has the highest proportion, the discharge is very severe. Formula 3 in: R i is the normalized value of the spectral intensity at the characteristic wavelength; I i is the spectral intensity value at the characteristic wavelength; c. According to the wavelength of 200-380nm as ultraviolet band, 380-780nm as visible light band, and 780-980nm as near infrared band, obtain the ultraviolet wave, visible light wave, and near infrared wave signals in the simulation cavity, and use formula 4 to calculate the number of photons in each band. Formula 4 By comparison: the number of photons in the ultraviolet band is dominant in the early stage of discharge, and the number of photons in the visible light band is dominant in the development stage of discharge. As the degree of discharge defects deepens, the proportion of photons in the ultraviolet band gradually decreases, while the proportion of photons in the visible light band gradually increases in the range of 200-780nm to determine the degree of discharge defects. d. Judgment: When the R 3 proportion is the highest at a wavelength of 500.7 nm, the proportion of photons in the visible light band is higher than that in the ultraviolet light band, and R g < 2, the partial discharge is already very serious and breakdown discharge may occur at any time, which should be noted and a warning should be issued.

2. The analysis method according to claim 1, wherein After the simulation cavity is filled with the mixed gas of SF6 and N2, it is left at room temperature for at least 12 hours to allow the gases to be fully mixed.

3. The analysis method according to claim 1, wherein The applied power frequency AC voltage ranges from 0 to 40 kV, the voltage gradient is 2 kV, and the duration of each voltage gradient is 15 minutes.

4. The analysis method according to claim 3, characterized in that, When the applied power frequency AC voltage is in the range of 0-40kV, the method further includes: when the boost discharge is performed until the discharge electrode and the shell are broken down, the high voltage generator cuts off the power input and automatically reduces the voltage through the built-in current protection action at the moment of breakdown.

5. The analysis method according to claim 1, characterized in that The gas main pipe is provided with a main control valve, which is arranged between the gas introduction interface of the cavity shell and the gas output control valves and vacuum extraction control valves of the two insulating gas cylinders. The detection valve is directly connected to the gas introduction interface of the cavity shell through the gas main pipe.

6. The analysis method according to claim 1, characterized in that, A transparent quartz glass observation window is provided on the cavity shell, and the optical fiber probe is arranged on the observation window.

7. The analysis method according to claim 1, characterized in that The simulation cavity is placed in a dark room, and a pressure gauge is provided on the simulation cavity for intuitively displaying the changes in the insulating gas pressure in the cavity.

8. The analysis method according to claim 1, characterized in that The optical fiber probe is equipped with an optical focusing lens for collecting photoluminescence radiation generated by partial discharge.

9. The analysis method according to claim 8, wherein The optical focusing lens is an optical focusing lens that can see through light in the 200-900nm wavelength band.

10. The analysis method according to claim 1, characterized in that The cavity is a cavity that can withstand at least 4 atmospheres of pressure.

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