Defect identification method based on SF6 / N2 mixed gas characteristic decomposition product

Abstract

The invention discloses a defect identification method based on a characteristic decomposition product of # imgabs 0 # mixed gas. The method comprises the following steps: carrying out partial discharge and overheating experiments on # imgabs 1 # mixed gas; and analyzing and detecting the generated decomposition products, finding out characteristic decomposition products, namely first gas and second gas, which can be distinguished from # imgabs3 # gas in # imgabs2 # mixed gas under different defect conditions, and determining the defect type of the electrical equipment by qualitative and quantitative analysis of the characteristic decomposition products.

Description

Technical Field

[0001] The present invention relates to the technical field of fault detection for hybrid gas electrical equipment, and particularly to a defect identification method based on the characteristic decomposition products of hybrid gas. Background Art

[0002] Pure has extremely strong arc extinguishing ability and insulation ability, and is widely used in power equipment. With the development of domestic and foreign economic technologies, the electricity consumption is increasing day by day, and electrical equipment has become more advanced and safer, making the usage of gas continuously rising.

[0003] In recent years, some exposed disadvantages, especially the greenhouse effect problem, have reached a point that cannot be ignored. Reducing the usage of gas in power equipment has been put on the agenda. In recent years, using SF 6 mixture as the internal insulation gas of the equipment to reduce the usage has been widely recognized and promoted at home and abroad. Researchers have found that has the advantages of stable chemical properties, low price, environmental protection, etc., and can be used to replace part of and be applied to electrical equipment. Therefore, for high-voltage equipment, the hybrid gas has great industrial potential.

[0004] However, in electrical equipment using hybrid gas as the insulating medium, there are usually a large number of joints. Due to manufacturing process problems, these joints may have defects such as detachment, uneven plating, or surface oxidation. These problems will lead to a reduction in the effective contact area of the joints or poor contact, resulting in an excessive loop contact resistance and causing local overheating. In addition, during the operation of electrical equipment, due to defects such as metal burrs and improper installation, component loosening may occur inside the equipment, leading to differences in electric field strength and causing partial discharge phenomena, and even possibly resulting in breakdown faults. Under these insulation defects, and may undergo a series of decomposition reactions to produce toxic and acidic substances. These decomposition products may damage the insulation performance of the equipment, causing problems such as a decrease in insulation performance, corrosion of the equipment surface, and a reduction in operation reliability. At the same time, these products also pose a potential threat to the life safety of operators. Therefore, proposing a defect identification method based on the characteristic decomposition products of hybrid gas is of great significance for the power industry to use hybrid gas. Summary of the Invention

[0005] An embodiment of the present application provides a method for defect identification based on decomposition products of a mixed gas. In this method, partial discharge and overheating experiments are carried out on the mixed gas. The generated decomposition products are analyzed and detected to find the decomposition products of the mixed gas that can be distinguished from the gas under different defect conditions, namely the first gas and the second gas. And by qualitatively and quantitatively analyzing the characteristic decomposition products, the type of defect occurring in the power equipment is determined.

[0006] The present invention provides a method for defect identification based on decomposition products of a mixed gas, including: Detecting the internal gas of an electrical equipment using a gas chromatograph, which uses the mixed gas as an insulating medium at the work site to determine the concentration of the characteristic decomposition products; wherein, the characteristic decomposition products include a first gas determined by a local overheating simulation device for identifying local overheating defects of the electrical equipment, and a second gas determined by a partial discharge simulation device for identifying partial discharge defects of the electrical equipment; Determining the defect of the electrical equipment according to the concentration of the first gas and the concentration of the second gas.

[0007] In some embodiments, the second gas is , and the first gas is ; the step of determining the defect of the electrical equipment according to the concentration of the first gas and the concentration of the second gas includes: If the concentration of the is greater than a first preset value, it is determined that the defect of the electrical equipment includes a local overheating defect; If the concentration of the is greater than a second preset value, it is determined that the defect of the electrical equipment includes a partial discharge defect.

[0008] In some embodiments, the local overheating simulation device includes a first housing, a first intake pipe, a first outlet pipe, a first vacuum pump, a first pressure gauge, a heating rod, a temperature control distribution box, and a power supply; The first intake pipe and the first outlet pipe are respectively communicated with the inside of the first housing, the first pressure gauge is arranged on the first intake pipe, and the first vacuum pump is arranged on the first outlet pipe; The heating rod is located inside the first housing, and the heating rod is connected through the temperature control distribution box and the power supply; A first cover plate is movably arranged at the upper end of the first housing.

[0009] In some embodiments, the method further includes: determining, by the local overheating simulation device, a first gas for identifying local overheating defects of the electrical equipment; Wherein the step of determining, by the local overheating simulation device, a first gas for identifying local overheating defects of the electrical equipment includes: Presetting first preset strategies, and taking the first of the first preset strategies as a first target strategy, wherein the first preset strategy includes a heating temperature and a first preset duration during heating of the heating rod; Inputting the mixed gas into the first housing through a first intake pipe to a first preset air pressure, and controlling the heating rod in the local overheating simulation device to heat under the first target strategy, and detecting a first decomposition product of the mixed gas during heating under the first target strategy; Taking the first preset strategy as the first target strategy, and repeatedly executing the step of inputting the mixed gas into the local overheating simulation device to the first preset air pressure, and controlling the heating rod in the local overheating simulation device to heat under the first target strategy, and detecting a first decomposition product of the mixed gas during heating under the first target strategy, where successively taking positive integers between ; Screening out, from the first decomposition products of the mixed gas, a first gas for identifying local overheating defects.

[0010] In some embodiments, the partial discharge simulation device includes a second housing, a second intake pipe, a second outlet pipe, a second pressure gauge, a second vacuum pump, a needle-plate electrode, a protective resistor, a high-voltage corona-free experimental power supply, and an oscilloscope; The second intake pipe and the second outlet pipe are respectively communicated with the interior of the second housing, and the second pressure gauge and the second vacuum pump are respectively arranged on the second outlet pipe; The needle-plate electrode is arranged inside the second housing, and the protective resistor, the high-voltage corona-free experimental power supply, and the oscilloscope are arranged outside the second housing; One end of the needle-plate electrode is connected to the high-voltage corona-free experimental power supply through the protective resistor, and the other end of the needle-plate electrode is connected to the oscilloscope; A second cover plate is movably arranged at the upper end of the second housing.

[0011] In some embodiments, the method further includes: determining, by the partial discharge simulation device, a second gas for identifying the partial discharge defect of the electrical equipment; Wherein the step of determining, by the partial discharge simulation device, a second gas for identifying the partial discharge defect of the electrical equipment includes: The step of determining, by the partial discharge simulation device, a second gas for identifying the partial discharge defect of the electrical equipment includes: Determining the partial discharge voltage of the partial discharge simulation device under an inherent defect; Presetting a plurality of second preset strategies, and taking the first of the a plurality of second preset strategies as the second target strategy, wherein the second preset strategy includes the voltage value during the needle-plate electrode discharge and the second preset duration of the discharge, and the voltage value is less than the partial discharge voltage under the inherent defect; Inputting the mixed gas into the second housing through the second intake pipe to a second preset air pressure, and controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, and detecting the second decomposition product of the mixed gas during the discharge under the second target strategy; Taking the jth second preset strategy as the second target strategy, and repeatedly executing the step of inputting the mixed gas into the second housing through the second intake pipe to a second preset air pressure, and controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, and detecting the second decomposition product of the mixed gas during the discharge under the second target strategy, wherein successively taking positive integers between; From the second decomposition products of the mixed gas, screening out a second gas for identifying the partial discharge defect.

[0012] In some embodiments, before the step of inputting the mixed gas into the second housing through the second intake pipe to a second preset air pressure, it further includes: Filling high-purity to clean the interior of the partial discharge simulation device, and repeating several times; Vacuuming the interior of the partial discharge simulation device.

[0013] In some embodiments, before the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, the following steps are further included: Let the partial discharge simulation device filled with the mixed gas stand still for several hours; before and after standing still, respectively use the second pressure gauge in the partial discharge simulation device to determine the internal pressure of the partial discharge simulation device; according to the internal pressures before and after standing still, judge whether the inside of the partial discharge simulation device has good airtightness; if the airtightness is good, then execute the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy.

[0014] In some embodiments, before the step of evacuating the inside of the partial discharge simulation device, the following steps are further included: filling with high-purity clean the inside of the partial discharge simulation device and repeat several times.

[0015] In some embodiments, after the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, the following steps are further included: Evacuate the inside of the partial discharge simulation device and fill it with Clean the inside of the partial discharge simulation device and repeat several times.

[0016] In some embodiments, the gas chromatograph is a portable gas chromatograph.

[0017] A defect identification method based on characteristic decomposition products of mixed gas provided by the present invention, in this method, through partial discharge and overheating experiments on the mixed gas. Analyze and detect the generated decomposition products, and find out the characteristic decomposition products in the mixed gas that can be distinguished from the gas under different defect conditions, namely the first gas and the second gas, and determine the type of defect occurring in the power equipment through the qualitative and quantitative analysis of the characteristic decomposition products. gas, that is, the first gas and the second gas, and determine the type of defect occurring in the power equipment through the qualitative and quantitative analysis of the characteristic decomposition products. Brief Description of the Drawings

[0018] Figure 1 Exemplarily shows a flowchart of a defect identification method based on characteristic decomposition products of mixed gas provided by some embodiments; Figure 2 Exemplarily shows a structural schematic diagram of a partial overheating simulation device provided by some embodiments; Figure 3Exemplarily shown is a characteristic decomposition product provided according to some embodiments Generate a bar chart of concentration varying with temperature and time; Figure 4 Exemplarily shown is a schematic structural diagram of a partial discharge simulation device provided according to some embodiments; Figure 5 Exemplarily shown is a kind of Curve of concentration of gas generation varying with time; Figure 6 Exemplarily shown is a schematic diagram of a detection result of a portable gas chromatograph provided according to some embodiments; Figure 7 Exemplarily shown is another schematic diagram of a detection result of a portable gas chromatograph provided according to some embodiments. Detailed implementation manners

[0019] To better understand the above technical solutions, the technical solutions of the present application will be described in detail below through specific implementation manners.

[0020] To solve the above technical problems, the embodiments of the present application provide a defect identification method based on characteristic decomposition products of mixed gas. In this method, local discharge and overheating experiments are carried out on the mixed gas. The generated decomposition products are analyzed and detected to find out the characteristic decomposition products in the mixed gas that can be distinguished from the gas under different defect conditions, namely the first gas and the second gas, and the type of defect occurring in the power equipment is determined by qualitative and quantitative analysis of the characteristic decomposition products.

[0021] Figure 1 Exemplarily shown is a flowchart of a defect identification method based on characteristic decomposition products of mixed gas provided according to some embodiments. The method includes S100 - S200.

[0022] S100. Detect the internal gas of the electrical equipment using the mixed gas as the insulating medium at the work site by using a gas chromatograph to determine the concentration of the characteristic decomposition products; wherein, the characteristic decomposition products include the first gas for identifying the local overheating defect of the electrical equipment determined by the local overheating simulation device, and the second gas for identifying the local discharge defect of the electrical equipment determined by the local discharge simulation device.

[0023] In some embodiments, the gas chromatograph is a portable gas chromatograph. In this embodiment, using a portable gas chromatograph is convenient for application at the work site for ​The first gas and the second gas of the mixed gas are detected, so that the characteristic decomposition products (i.e., the first gas and the second gas) can be measured simply and quickly, guiding the on-site staff to maintain the power equipment accurately and in a timely manner, improving the reliability of the operation of the power equipment, and ensuring the safety of the power grid. By controlling the valve switching action of the portable gas chromatograph, the interference of other decomposition products to the detection is avoided, and the detection accuracy of the detection method is improved.

[0024] In the embodiment of the present application, an exhaust gas treatment device can be added, and the exhaust gas treatment device can treat the gas discharged from the portable gas chromatograph.

[0025] Before performing step S100, a local overheating simulation device and a partial discharge simulation device are respectively pre-built, and a fault simulation experiment is carried out on the mixed gas to determine the first gas for identifying local overheating defects and the second gas for identifying partial discharge defects. The first decomposition product and the second decomposition product are collected from the outlet pipes of the two devices, namely the first outlet pipe and the second outlet pipe, of the mixed gas and sent to a gas chromatography-mass spectrometry (GC-MS) for qualitative and quantitative analysis, and finally the first gas for identifying local overheating defects and the second gas for identifying partial discharge defects are screened out. Specifically, the first gas is determined by using the built local overheating simulation device, and the second gas is determined by using the built partial discharge simulation device.

[0026] First, the structure of the local overheating simulation device is introduced.

[0027] In some embodiments, Figure 2 The structural schematic diagram of a local overheating simulation device provided according to some embodiments is exemplarily shown. The local overheating simulation device includes a first housing 1, a first intake pipe 2, a first outlet pipe 3, a first vacuum pump 4, a first pressure gauge 5, a heating rod 6, a temperature control distribution box 7, and a power supply 8.

[0028] The first intake pipe and the first outlet pipe are respectively communicated with the inside of the first housing, the first pressure gauge is arranged on the first intake pipe, and the first vacuum pump is arranged on the first outlet pipe.

[0029] In some embodiments, the first intake pipe and the first outlet pipe are arranged on the same side of the first housing, The mixed gas enters the inside of the first housing from the first intake pipe and discharges from the first outlet pipe.

[0030] The first pressure gauge is used to measure the gas pressure inside the first housing. The first vacuum pump can extract gas from the inside of the first housing to make the inside of the first housing in a vacuum state.

[0031] The heating rod is located inside the first housing and provides heat energy inside the first housing. The heating rod is connected to the power supply through the temperature control distribution box. In the embodiment of the present application, the power supply provides electrical energy to the heating rod through the temperature control distribution box and the power cord 18. In addition, the temperature control distribution box is also connected to the heating rod through the temperature measurement wire 19. This temperature measurement wire is used to detect the temperature of the heating rod and transmit the temperature signal to the temperature control distribution box. The temperature control distribution box further controls the electrical energy provided by the power supply to the heating rod based on the obtained temperature signal to adjust the temperature of the heating rod. The temperature control distribution box can display the real-time temperature and the set temperature inside the first housing, and control the heating rod to increase the heating temperature when the real-time temperature does not reach the set temperature.

[0032] A first cover plate is movably arranged at the upper end of the first housing. The first cover plate is movably arranged at the upper end of the first housing and can be removed from the upper end of the first housing as needed or covered on the upper end of the first housing.

[0033] In this embodiment, The mixed gas is sent into the inside of the first housing through the first intake pipe, the heating temperature of the heating rod is controlled, and samples are taken through the first outlet pipe at preset time intervals, and the sampled gas is detected by a gas chromatography-mass spectrometry instrument.

[0034] In the embodiment of the present application, an exhaust gas treatment device can be added, and this exhaust gas treatment device can treat the gas after being detected by the gas chromatography-mass spectrometry instrument.

[0035] After building a local overheating simulation device, the first gas is determined using the local overheating simulation device.

[0036] Specifically, the method further includes: determining, using the local overheating simulation device, a first gas for identifying local overheating defects of the electrical equipment; wherein the step of determining, using the local overheating simulation device, a first gas for identifying local overheating defects of the electrical equipment includes S101 - S104.

[0037] S101. Preset a first preset strategy, and use the first preset strategy among the first preset strategies as the first target strategy, where the first preset strategy includes the heating temperature when the heating rod is heating and the first preset duration of heating.

[0038] Exemplarily, The first preset strategy can be 11 first preset strategies, the first ten first preset strategies are heating temperatures of 200° C., the last first preset strategy is 25° C. higher than the previous first preset strategy in heating temperature, and the eleventh first preset strategy is 450° C. The first preset time length in each first preset strategy is 10 hours.

[0039] S102, the The mixed gas is input into the first housing through the first air intake pipe to a first preset air pressure, and the heating rod in the local overheating simulation device is controlled to heat under the first target strategy, and the heating under the first target strategy is detected. The first decomposition product of the gas mixture.

[0040] In the embodiment of the present application, in order to ensure the experimental results, that is, to determine the accuracy of the first gas, the temperature and humidity of the laboratory where the local overheating simulation device is located are controlled during the experiment so that the temperature and humidity are roughly the same as the environment at the work site, and are exemplarily maintained at 20±2°C and 50±3% relative humidity.

[0041] Through investigation in the present application embodiment, it is found that there are pilot runs The operating pressure of the mixed gas equipment is 0.6Mpa. In mixed gas and The mixing ratio is 3:7, so in order to be more similar to the actual scene at the work site, fill it in this step and The mixing ratio is 3:7 The mixed gas is added to the local overheating simulation device so that the gas pressure in the first shell is 0.6 MPa, that is, the first preset gas pressure is 0.6 MPa.

[0042] In one example, the first decomposition product may be collected from the first gas outlet pipe once per hour using a collection bag, that is, the first decomposition product is collected 10 times in this example.

[0043] The first decomposition product is detected by using a gas chromatography-mass spectrometer, and the first decomposition product is qualitatively and quantitatively analyzed, that is, the specific substance of the first decomposition product and the concentration of the first decomposition product are analyzed.

[0044] In one example, when the first target strategy is 200°C, the The mixed gas is input into the first shell to a temperature of 0.6 MPa, and the heating rod in the local overheating simulation device is controlled to heat at 200°C for 10 hours, and the heating rate per hour under the first target strategy is detected. The first decomposition product of the gas mixture.

[0045] In some embodiments, before the step of inputting the mixed gas into the first housing through the first intake pipe to a first preset air pressure, the following steps are further included: Filling with high-purity cleaning the interior of the local overheating simulation device for several times; evacuating the interior of the local overheating simulation device.

[0046] Exemplarily, high-purity can be filled to make the internal pressure of the local overheating simulation device reach 0.2 - 0.3 Mpa, and the interior of the local overheating simulation device is cleaned 3 times. This can ensure that all gas impurities inside the local overheating simulation device are discharged, guaranteeing the accuracy and reliability of subsequent experiments.

[0047] In some embodiments, before the step of filling with high-purity cleaning the interior of the local overheating simulation device for several times, the following steps are further included: removing the first cover, wiping the interior of the local overheating simulation device with an anti-static dust-free cloth wetted with anhydrous ethanol to ensure that the inner wall of the local overheating simulation device is clean without impurities, avoiding any influence on the experimental results. Then reinstalling the first cover on the upper end of the local overheating simulation device, evacuating the interior of the local overheating simulation device to ensure good airtightness of the device.

[0048] In some embodiments, before the step of controlling the heating rod in the local overheating simulation device to heat under the first target strategy, the following steps are further included: Letting the local overheating simulation device filled with the mixed gas stand for several hours; before and after standing, respectively using the first pressure gauge in the local overheating simulation device to determine the internal pressure of the local overheating simulation device; judging whether the interior of the local overheating simulation device has good airtightness according to the internal pressures before and after standing; if the airtightness is good, then performing the step of controlling the heating rod in the local overheating simulation device to heat under the first target strategy.

[0049] In some embodiments, heating under the first target strategy After the mixed gas, after detecting the first decomposition product by a gas chromatography-mass spectrometer, it further includes: evacuating the inside of the local overheating simulation device, for example, it can be evacuated to -0.1 Mpa, and filling it with nitrogen and repeating the cleaning several times. This can avoid the release of the first decomposition product in the local overheating simulation device when removing the first cover body and ensure the safety of the experimental personnel. In one example, nitrogen is filled so that the internal pressure of the local overheating simulation device is 0.3 - 0.4 Mpa, and the cleaning is repeated 3 times.

[0050] S103. Determine the th first preset strategy as the first target strategy, and repeatedly execute step S102, the step of inputting the mixed gas through the first intake pipe into the first housing to the first preset pressure, and controlling the heating rod in the local overheating simulation device to heat under the first target strategy, and detecting the first decomposition product of the mixed gas when heating under the first target strategy, where successively take positive integers between.

[0051] In the embodiments of the present application, since the number of first preset strategies may be multiple, it is necessary to detect the first decomposition product of the mixed gas when heating under each first preset strategy.

[0052] S104. From the first decomposition product of the mixed gas, screen out the first gas for identifying local overheating defects.

[0053] In the example where the above-mentioned first preset strategies can be 11 first preset strategies, no sulfur- and nitrogen-containing decomposition products were detected in the and mixed gas under the condition of 175 °C, and only trace amounts of and and gases were detected. Considering that this may be the influence of air mixing during the gas collection process or impurities in the new gas, it can be ignored. Therefore, it is considered that the mixed gas did not decompose at this temperature. When the temperature was raised to 200 °C, a small amount of and The initial decomposition temperatures of the single gas are basically the same. In this study, 10 groups of experiments were conducted, including 9 groups of experiments at intervals of 25 °C from 200 °C to 400 °C, and a high-temperature experiment at 450 °C. The results show that The decomposition products of the mixed gas under overheating conditions are , , , , , , , Eight kinds of products. In this overheating fault simulation test, the nitrogen-containing decomposition product detected is , which can be used as the first gas for identifying local overheating defects, that is The overheating defect characteristic decomposition product of the mixed gas different from pure gas. Among them, the column chart of the generation concentration of the characteristic decomposition product changing with temperature and time is as shown in Figure 3 .

[0054] In the embodiment of the present application, compared with the traditional pure gas, due to the addition of nitrogen in the mixed gas, after the local overheating simulation device heats the mixed gas, nitrogen-containing decomposition products will be generated. Therefore, the steps of screening out the first gas for identifying local overheating defects from the first decomposition products of the mixed gas may include: finding the nitrogen-containing gas from all the first decomposition products obtained by heating under the first target strategy, and determining the nitrogen-containing gas as the first gas, that is , which can significantly distinguish the decomposition products of the traditional pure gas.

[0055] Secondly, the structure of the partial discharge simulation device is introduced.

[0056] In some embodiments, Figure 4 An exemplary structural schematic diagram of a partial discharge simulation device provided according to some embodiments is shown. The partial discharge simulation device includes a second housing 9, a second intake pipe 10, a second outlet pipe 11, a second pressure gauge 12, a second vacuum pump 13, a needle-plate electrode 14, a protective resistor 15, a high-voltage corona-free experimental power supply 16, and an oscilloscope 17.

[0057] The second intake pipe and the second outlet pipe are respectively communicated with the inside of the second housing, and the second pressure gauge and the second vacuum pump are respectively arranged on the second outlet pipe.

[0058] In some embodiments, the second intake pipe and the second outlet pipe are arranged on opposite sides of the second housing. The mixed gas enters the interior of the second housing through the second intake pipe and exits the second housing through the second outlet pipe.

[0059] The second pressure gauge is used to measure the gas pressure inside the second housing. The second vacuum pump can extract gas from the interior of the second housing to make the interior of the second housing in a vacuum state.

[0060] The needle-plate electrode is arranged inside the second housing, and the protective resistor, the high-voltage corona-free experimental power supply and the oscilloscope are arranged outside the second housing; in this embodiment, the high-voltage corona-free experimental power supply provides electrical energy for the needle-plate electrode so that the needle-plate electrode can discharge in the discharge chamber 20.

[0061] One end of the needle-plate electrode is connected to the high-voltage corona-free experimental power supply through the protective resistor, and the other end of the needle-plate electrode is connected to the oscilloscope. The oscilloscope is used to display the discharge voltage of the needle-plate electrode.

[0062] The upper end of the second housing is movably provided with a second cover plate. The second cover plate is movably arranged on the upper end of the second housing. The second cover plate can be removed from the upper end of the second housing as needed or can be covered on the upper end of the second housing.

[0063] In this embodiment, The mixed gas is sent into the interior of the second housing through the second intake pipe, the needle-plate electrode is controlled to be energized, samples are taken through the second outlet pipe at preset intervals, and the sampled gas is detected by a gas chromatography-mass spectrometry instrument.

[0064] In the embodiment of the present application, an exhaust gas treatment device can be added, and the exhaust gas treatment device can treat the gas after being detected by the gas chromatography-mass spectrometry instrument.

[0065] After building the partial discharge simulation device, the second gas is determined by using the partial discharge simulation device.

[0066] Specifically, the method further includes: determining, by using the partial discharge simulation device, a second gas for identifying the partial discharge defect of the electrical equipment. Among them, the step of determining, by using the partial discharge simulation device, a second gas for identifying the partial discharge defect of the electrical equipment includes S105-S109.

[0067] S105. Determine the partial discharge voltage of the partial discharge simulation device under inherent defects.

[0068] The step of determining the partial discharge voltage of the partial discharge simulation device under inherent defects includes: The mixed gas is input into the second housing through the second intake pipe to a second preset air pressure, and the high-voltage corona-free experimental power supply is controlled to be energized so that the needle-plate electrode in the partial discharge simulation device is at the target voltage, and it is determined whether the needle-plate electrode is broken down.

[0069] In this embodiment, during the process of determining the partial discharge voltage under the inherent defect The second preset air pressure in the second housing after the mixed gas is filled and in step S107 are the same. In addition, In the mixed gas and the mixing ratio of is the same as the mixing ratio of the mixed gas filled into the partial discharge simulation device in step S107. In addition, the humidity and temperature at which the partial discharge simulation device is located are also the same as the temperature and humidity at which the partial discharge simulation device is located in step S107.

[0070] If it is broken down, the target voltage can be reduced. Re-execute the step of inputting the mixed gas into the second housing through the second intake pipe to the second preset air pressure, and controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges at the target voltage, until the needle-plate electrode will not be broken down at the target voltage, and determine this target electrode as the partial discharge voltage under the inherent defect.

[0071] In this embodiment, the target voltage is set according to experience. The setting basis of this target voltage is that the needle-plate electrode will not be broken down. Exemplarily, the target voltage can be set to 40 kV. However, because it is set according to experience, the target voltage is not necessarily accurate, and it is necessary to use the partial discharge simulation device to conduct actual tests to determine the partial discharge voltage under the inherent defect. In the embodiment of the present application, in the actual test, it is found that when the target voltage is set to 40 kV, the needle-plate voltage will not be broken down, so 40 kV is set as the partial discharge voltage under the inherent defect.

[0072] S106. Preset a second preset strategy, and use the first second preset strategy among the second preset strategies as the second target strategy, where the second preset strategy includes the voltage value when the needle-plate electrode discharges and the second preset duration of the discharge, and the voltage value is less than the partial discharge voltage under the inherent defect.

[0073] Exemplarily, The second preset strategy may be four second preset strategies. The first second preset strategy includes a voltage value of 10 kV when the needle-plate electrode discharges, and a second preset duration of 10 hours for the discharge. The second second preset strategy includes a voltage value of 12 kV when the needle-plate electrode discharges, and a second preset duration of 10 hours for the discharge. The third second preset strategy includes a voltage value of 18 kV when the needle-plate electrode discharges, and a second preset duration of 10 hours for the discharge. The fourth second preset strategy includes a voltage value starting from 10 kV when the needle-plate electrode discharges, with a voltage increase of 0.5 kV per hour until the voltage reaches 15 kV, and a second preset duration of 10 hours for the discharge.

[0074] In the embodiments of the present application, in order to avoid the breakdown of the needle-plate electrode, which may affect the process of determining the second gas for identifying the partial discharge defect of the electrical equipment, the target voltage at which the needle-plate electrode cannot be broken down is first determined, that is, the partial discharge voltage under the inherent defect. Subsequently, the voltage values when the needle-plate electrode discharges in the preset second preset strategies are all less than the partial discharge voltage under the inherent defect.

[0075] S107. Input the mixed gas into the second housing through the second intake pipe to a second preset air pressure, and control the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, and detect the second decomposition product of the mixed gas during the discharge under the second target strategy.

[0076] In the embodiments of the present application, in order to ensure the experimental results, that is, the accuracy of determining the second gas, the temperature and humidity of the laboratory where the partial discharge simulation device is located are controlled during the experiment. Exemplarily, it is maintained at 20 ± 2 °C and a relative humidity of 50 ± 3%.

[0077] In some embodiments, before the step of inputting the mixed gas into the second housing through the second intake pipe to a second preset air pressure, it further includes: filling high-purity to clean the inside of the partial discharge simulation device for several times; evacuating the inside of the partial discharge simulation device.

[0078] Exemplarily, high-purity can be filled to make the internal pressure of the partial discharge simulation device reach 0.2 - 0.3 Mpa, and the inside of the partial discharge simulation device is cleaned 3 times. This can ensure that all gas impurities inside the partial discharge simulation device are discharged, ensuring the accuracy and reliability of subsequent experiments.

[0079] In some embodiments, before filling high-purity Before repeating the steps of cleaning the interior of the partial discharge simulation device several times, it further includes: removing the second cover, wiping the interior of the partial discharge simulation device with an anti-static dust-free cloth moistened with anhydrous ethanol to ensure that the inner wall of the partial discharge simulation device is clean without impurities, avoiding any impact on the experimental results. Then reinstall the second cover on the upper end of the partial discharge simulation device, and evacuate the interior of the partial discharge simulation device to ensure good airtightness of the device.

[0080] In some embodiments, before the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, it further includes: Let the partial discharge simulation device filled with the mixed gas stand still for several hours; before and after standing still, respectively use the second pressure gauge in the partial discharge simulation device to determine the internal pressure of the partial discharge simulation device; according to the internal pressure before and after standing still, judge whether the airtightness of the interior of the partial discharge simulation device is good; if the airtightness is good, then execute the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy.

[0081] In some embodiments, after the step of controlling the high-voltage corona-free experimental power supply to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, it further includes: Evacuate the interior of the partial discharge simulation device and fill it with Clean the interior of the partial discharge simulation device and repeat several times.

[0082] In this embodiment, after each execution according to the second target strategy, that is, after each group of experiments, evacuate the interior of the partial discharge simulation device to -0.1 Mpa and fill it with nitrogen with a pressure of 0.3 to 0.4 Mpa, and repeat the cleaning three times to avoid releasing residual decomposition gases when opening the second cover to ensure the safety of experimental personnel.

[0083] In this embodiment, when detecting the second decomposition product of the mixed gas during discharge under the second preset strategy, it can be to collect the second decomposition product of the mixed gas in the partial discharge simulation device once every hour using a Teflon sampling bag. Detect the second decomposition product using a gas chromatography-mass spectrometry instrument and perform qualitative and quantitative analysis on the second decomposition product.

[0084] S108. Set the nth second preset strategy as the second target strategy and repeat the execution of the The mixed gas is input into the second housing through the second intake pipe to a second preset air pressure, and the high-voltage corona-free experimental power supply is controlled to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under a second target strategy, and the second decomposition products of the mixed gas during discharge under the second target strategy are detected, where successively take positive integers between.

[0085] In the embodiments of the present application, since there may be multiple second preset strategies, it is necessary to detect the second decomposition products of the mixed gas when heating under each first preset strategy.

[0086] S109. From the second decomposition products of the mixed gas, a second gas for identifying partial discharge defects is screened out.

[0087] In the example mentioned above where the number of second preset strategies can be four, the decomposition products detected in this experiment under partial discharge conditions are , , , , and . Among them, the three main decomposition products with the highest concentrations are successively , and . is only detected at a voltage of 18 kV during the 9th and 10th hours of partial discharge, and the concentrations are 0.326 μL / L and 0.679 μL / L respectively, indicating that is generated only under the conditions of intense and long-lasting discharge. And and have gas production concentrations not exceeding 1 μL / L, and have a certain degree of dispersion, and are not suitable for analysis as characteristic products. Since gas is not detected in the overheating experiment products and is a characteristic product under partial discharge conditions. Therefore the generation of gas can be used as a characteristic identification product for partial discharge defects, that is, the second gas, and gas can be used as a characteristic decomposition product of the mixed gas different from pure gas. The concentration change curve of Figure 5 gas generated over time is as follows

[0088] ​S200. Determine the defects of the electrical equipment according to the concentrations of the first gas and the second gas.

[0089] In some embodiments, the second gas is , and the first gas is ; the step of determining the defects of the electrical equipment according to the concentrations of the first gas and the second gas includes: If the concentration of is greater than a second preset value, it is determined that the defects of the electrical equipment include partial discharge defects; If the concentration of is greater than a first preset value, it is determined that the defects of the electrical equipment include local overheating defects.

[0090] In the embodiments of the present application, the second preset value and the first preset value are set according to actual needs. In one example, both the second preset value and the first preset value are 0, that is, when there is , it is determined that the defects of the electrical equipment include partial discharge defects, and when there is , it is determined that the defects of the electrical equipment include local overheating defects.

[0091] The method in the embodiments of the present application first proposes, through research on experimental data and decomposition product detection and analysis, that the mixed gas has characteristic decomposition products different from traditional , namely the first gas and the second gas, filling the gap in the research field of characteristic decomposition products of the mixed gas, promoting the application of the mixed gas, providing equipment operation and maintenance guidance for power equipment using the mixed gas as an insulating medium, improving the working stability of equipment using the mixed gas, and contributing to reducing emissions.

[0092] Combined with the conducted tests and test results, it is first proposed to use gas and gas as The characteristic products of local overheating defects and local discharge defects of mixed gases are detected by portable gas chromatograph. Compared with the gas chromatograph-mass spectrometer used in the laboratory, this detection method is convenient and has few detection conditions. It can be applied to on-site detection and can be used at the working site of power equipment, avoiding the trouble of collecting gas and bringing it back to the laboratory for measurement, as well as the risks of leakage and composition changes during transportation. It improves the efficiency and timeliness of detection, and can help on-site staff to maintain equipment more timely and accurately, improve the reliability of equipment operation, and ensure the safe operation of the power grid.

[0093] After the test, add exhaust gas treatment equipment to avoid The toxic and non-environmentally friendly gases produced by the decomposition products of the mixed gas pollute the atmosphere and threaten the health of on-site workers.

[0094] In one example, Figure 6 A schematic diagram of detection results of a portable gas chromatograph provided according to some embodiments is exemplified. Figure 7 Another schematic diagram of detection results of a portable gas chromatograph provided according to some embodiments is exemplarily shown.

[0095] In summary, the present invention provides a method based on A defect identification method for characteristic decomposition products of mixed gases is carried out by The mixed gas is subjected to partial discharge and overheating experiments. The decomposition products produced are analyzed and tested to find out the causes of different defects. In the mixed gas, The characteristic decomposition products of the gas, namely the first gas and the second gas, can be used to determine the type of defects in the power equipment through qualitative and quantitative analysis of the characteristic decomposition products.

[0096] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed. The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application. The above are only preferred implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A method based on The defect identification method of the characteristic decomposition products of mixed gas is characterized by: include: Used on the job site The internal gas of the electrical equipment with the mixed gas as the insulating medium is detected by a gas chromatograph to determine the concentration of characteristic decomposition products; wherein the characteristic decomposition products include a first gas determined by a local overheating simulation device for identifying a local overheating defect of the electrical equipment, and a second gas determined by a local discharge simulation device for identifying a local discharge defect of the electrical equipment; A defect of the electrical device is determined based on the concentration of the first gas and the concentration of the second gas.

2. The method according to claim 1, characterized in that The second gas is , the first gas is ; The step of determining the defect of the electrical equipment according to the concentration of the first gas and the concentration of the second gas comprises: If the If the concentration of is greater than a first preset value, it is determined that the defect of the electrical equipment includes the local overheating defect; If the If the concentration of the partial discharge defect is greater than a second preset value, it is determined that the defect of the electrical equipment includes the partial discharge defect.

3. The method according to claim 1, characterized in that The local overheating simulation device comprises a first shell, a first air inlet pipe, a first air outlet pipe, a first vacuum pump, a first pressure gauge, a heating rod, a temperature control distribution box and a power supply; The first air inlet pipe and the first air outlet pipe are respectively communicated with the interior of the first housing, the first pressure gauge is arranged on the first air inlet pipe, and the first vacuum pump is arranged on the first air outlet pipe; The heating rod is located inside the first shell, and the heating rod is connected to the power supply through the temperature control distribution box; A first cover plate is movably provided on the upper end of the first shell.

4. The method according to claim 3, characterized in that Also includes: Determining, by means of the local overheating simulation device, a first gas for identifying a local overheating defect of the electrical device; The step of determining the first gas for identifying the local overheating defect of the electrical equipment by the local overheating simulation device comprises: Preset A first preset strategy and The first of the first preset strategies is used as the first target strategy, wherein the first preset strategy includes a heating temperature when the heating rod is heated and a first preset heating time; The The mixed gas is input into the first housing through the first air intake pipe to a first preset air pressure, and the heating rod in the local overheating simulation device is controlled to heat under the first target strategy, and the heating rod is detected when heating under the first target strategy. The first decomposition product of the gas mixture; The first The first preset strategy is determined as the first target strategy, and the first preset strategy is repeatedly executed. The mixed gas is input into the first housing through the first air intake pipe to the first preset air pressure, and the heating rod in the local overheating simulation device is controlled to heat under the first target strategy, and the heating rod is detected when heating under the first target strategy. The step of mixing the first decomposition products of the gas, wherein Take A positive integer between ; From the said The first decomposition product of the mixed gas is screened out to be used for identifying the local overheating defect.

5. The method according to claim 1, characterized in that The partial discharge simulation device comprises a second housing, a second air inlet pipe, a second air outlet pipe, a second pressure gauge, a second vacuum pump, a needle-plate electrode, a protective resistor, a high-voltage non-corona experimental power supply and an oscilloscope; The second air inlet pipe and the second air outlet pipe are respectively communicated with the interior of the second shell, and the second pressure gauge and the second vacuum pump are respectively arranged on the second air outlet pipe; The needle-plate electrode is arranged inside the second shell, and the protection resistor, the high-voltage non-corona experimental power supply and the oscilloscope are arranged outside the second shell; One end of the needle-plate electrode is connected to the high-voltage non-corona experimental power supply through the protection resistor, and the other end of the needle-plate electrode is connected to the oscilloscope; A second cover plate is movably provided on the upper end of the second shell.

6. The method according to claim 5, characterized in that Also includes: Determining, by the partial discharge simulation device, a second gas for identifying a partial discharge defect of the electrical device; The step of determining the second gas for identifying the partial discharge defect of the electrical equipment by the partial discharge simulation device comprises: Determining the partial discharge voltage of the partial discharge simulation device under inherent defects; Preset A second preset strategy and a first one of the second preset strategies as the second target strategy, wherein the second preset strategy includes a voltage value when the needle-plate electrode discharges and a second preset discharge duration, wherein the voltage value is less than the partial discharge voltage under the inherent defect; Will The mixed gas is input into the second shell through the second air inlet pipe to a second preset air pressure, and the high-voltage non-corona experimental power supply is controlled to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, and the discharge under the second target strategy is detected. A second decomposition product of the gas mixture; The first The second preset strategy is determined as the second target strategy, and the second preset strategy is repeatedly executed. The mixed gas is input into the second shell through the second air inlet pipe to the second preset air pressure, and the high-voltage non-corona experimental power supply is controlled to be energized so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, and the discharge under the second target strategy is detected. The step of producing a second decomposition product of the mixed gas, wherein Take A positive integer between ; From the said The second decomposition product of the mixed gas is screened out to be used for identifying the partial discharge defect.

7. The method according to claim 6, characterized in that In the said Before the step of inputting the mixed gas into the second housing through the second air intake pipe to a second preset air pressure, the method further includes: Filled with high purity Cleaning the interior of the partial discharge simulation device, repeating several times; The interior of the partial discharge simulation device was evacuated.

8. The method according to claim 6, characterized in that Before the step of controlling the high-voltage corona-free experimental power supply to be powered on so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, the method further includes: will be charged into the The partial discharge simulation device of the mixed gas is allowed to stand for several hours; before and after the standing still, the internal pressure of the partial discharge simulation device is determined using the second pressure gauge in the partial discharge simulation device; based on the internal pressure before and after the standing still, it is judged whether the interior of the partial discharge simulation device is airtight; if the airtightness is good, the step of energizing the high-voltage corona-free experimental power supply to allow the needle-plate electrode in the partial discharge simulation device to discharge under the second target strategy is executed.

9. The method according to claim 6, characterized in that After the step of controlling the high-voltage corona-free experimental power supply to be powered on so that the needle-plate electrode in the partial discharge simulation device discharges under the second target strategy, the method further includes: The interior of the partial discharge simulation device is evacuated and filled with The interior of the partial discharge simulation device is cleaned, and the process is repeated several times.

10. The method according to claim 1, characterized in that The gas chromatograph is a portable gas chromatograph.

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