Low-air-pressure insulation support direct-current pollution flashover experiment testing device and method

Abstract

The invention discloses a low-air-pressure insulation support direct-current pollution flashover experiment testing device and method. The device comprises a voltage-multiplying rectification direct-current power supply and an artificial climate chamber. The method comprises the following steps: pretreating a test sample, and removing lipid substances and other dirt residues by using an absolute ethyl alcohol solution; the contamination method of the test sample comprises the following steps: simulating contamination by adopting a solid layer method, simulating soluble substances by using NaCl, and simulating insoluble substances by using kaolin; drying the sample in the shade, and standing for 24 hours until a surface dirt layer is dried; when a low-pressure environment is generated, putting the test sample into an artificial climate laboratory, and after determining that the artificial climate laboratory is completely sealed, starting to exhaust until a target pressure is reached; wetting the test object, namely wetting a dirt layer of the test object insulator by adding steam mist into the climate chamber; and pressurizing operation is carried out, pressurizing is started to carry out a flashover test when sufficient wetting is carried out, and the pressurizing method is a uniform pressurizing method. The method has the advantages that by considering that a low-air-pressure area in China is inland and natural contamination components are not single, the contamination process is simulated by adopting a solid layer method, the simulation environment of a test sample is closer to a real environment, and the experiment is more accurate; by utilizing the automatic control of the phytotron, the air pressure value of the environment where the test object is located can be more accurately controlled, so that the low-pressure environment is more truly simulated, and a technical means is provided for an external insulation low-pressure discharge test.

Description

Technical Field

[0001] The invention relates to the technical field of electrical engineering, and in particular to a device and method for a DC pollution flashover test of a low-pressure insulating support. Background Art

[0002] With the rapid development of my country's economy and the increasing demand for travel, high-speed rail trains are being vigorously developed. Building high-speed rail in the high-altitude areas of the west is a global problem, which requires consideration of a series of extreme weather conditions such as low pressure in the high-altitude areas of the west.

[0003] The research on high voltage external insulation characteristics belongs to experimental science, with many and complex influencing factors. Many phenomena cannot be analyzed by theoretical calculations or reduced model tests alone. Due to the limitations of research conditions, most of them are still only carried out in non-full-scale experimental research in non-high altitude areas, or only in experimental research under fixed altitude conditions in a certain place, which has great research limitations. Summary of the invention

[0004] The object of the present invention is to provide a test device and method for a DC pollution flashover test of a low-pressure insulating support.

[0005] In order to solve the problems raised in the above background technology, the present invention provides the following technical solutions: a low-pressure insulating bracket DC pollution flashover test device and method, comprising the following steps:

[0006] Step 1: Pretreatment of the sample. To avoid test errors caused by the original dirt on the sample surface, the sample needs to be cleaned before the dirt test. The specific steps are: use anhydrous ethanol solution to remove lipid substances and other dirt residues, then wash the sample surface with clean water, and then let it stand until the sample surface is dry;

[0007] Step 2: Pollution method of the sample. Although the composition of natural pollution is complex, it can be generally divided into two categories: soluble and insoluble. In the flashover process, the main function of insoluble matter is to absorb water and moisten the pollution layer. Soluble matter forms conductive ions after dissolving in water, which affects the surface insulation strength. Use NaCl to simulate the soluble matter in the pollution, and use highly absorbent diatomaceous earth, kaolin and other materials to simulate the insoluble matter in the pollution. The two are weighed in proportion, and deionized water is added to make a sewage liquid and applied to the surface of the sample. After it dries, add artificial mist to moisten it, and apply a test voltage;

[0008] Step 3: Dry the sample in the shade. After artificial contamination, the sample should be left to stand for 24 hours to allow the surface dirt to dry. During this period, care should be taken to prevent dirt from the environment from settling on the sample surface, which could cause test errors.

[0009] Step 4: Create a low-pressure environment. For the convenience of engineering applications, the air pressure is usually directly linked to the altitude. The test sample is placed in an artificial climate laboratory. After the artificial climate laboratory is completely sealed, start pumping until the target air pressure is reached. During the process of pumping air pressure, the pumping speed should be sufficient to prevent condensation on the surface of the test sample.

[0010] Step 5: Wetting of the test piece. The dirt layer of the test piece insulator is moistened by adding steam mist to the climate chamber. The steam mist can be provided by a boiler. The vent holes are located in the corners around the climate chamber. The test piece is placed in the center of the climate chamber so that the jet distance is far enough to meet the test requirements. At the same time, the test environment temperature should be within the range of 30 to 35 degrees Celsius. Affected by the hot mist, the indoor ambient temperature rises. When the ambient temperature exceeds this range, it should be adjusted through the refrigeration system. Since the test environment is in a low-pressure state, when the valve is opened to let in hot mist, the air pressure in the artificial climate chamber will increase. In order to maintain the air pressure at a predetermined value, the exhaust equipment should be turned on during the introduction of hot mist, thereby ensuring that the flashover test can be carried out immediately when the test piece is fully moistened, thereby improving the accuracy of the test results;

[0011] Step 6: Pressurization operation method. Start pressurizing for flashover test when fully wetted. The pressurization method is uniform pressure increase method. In order to improve accuracy and reduce test errors, repeated tests are required. The implementation method is: 3 to 5 test pieces are contaminated at one degree of contamination, and a single test piece flashes 4 to 5 times. After each flashover test, the results are recorded. Among the results obtained, the average value of the test results with a relative error of less than 10% is taken as the flashover voltage.

[0012] As a further solution of the present invention: in the step 2, the commonly used contamination methods in the artificial contamination test include salt spray method and solid layer method. The salt spray method uses a salt solution to simulate contamination. The salt solution is prepared with NaCl and deionized water according to the required salinity, and then the prepared salt solution is atomized by compressed air, and the salt spray is sprayed on the test sample through a nozzle. This contamination method is mainly used to simulate the operating environment of coastal areas. my country's low-pressure areas are inland, so it is not suitable to use the salt spray method. The solid layer method is used to simulate contamination, using NaCl to simulate solubles and kaolin to simulate insolubles. The ratio of solubles to insolubles is 1:4, and a 10% margin should be added when mixing the solutions of solubles and insolubles. The contamination should be completed within 1 hour after the pretreatment of the test sample.

[0013] As a further solution of the present invention: in the step 4, the air pressure p is used as a characteristic quantity of the influence of the atmospheric parameters on the discharge voltage, and its relationship with the altitude H can be expressed as:

[0014]

[0015] Where: p0 is the air pressure under standard atmospheric pressure, 101.3kPa. During the process of pumping air, the pumping speed should be sufficient to prevent condensation on the surface of the insulator, and the pumping speed should be controlled at a height change rate of 5m / s.

[0016] As a further solution of the present invention: in the step 5, the wetness characteristic of the surface of the test sample should be a continuous water film without dripping down.

[0017] As a further solution of the present invention: in step 6, the uniform boosting method boosting rate is 1 kV / s, and the average pollution flashover voltage and relative standard deviation can be expressed as:

[0018]

[0019] Where: U f Indicates the average pollution flashover voltage of the insulator; U fi represents the i-th pollution flashover voltage; N represents the number of tests; σ% represents the relative standard deviation of the test results.

[0020] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The present invention adopts the solid layer method to realize the contamination of the sample. Most of the high-altitude areas are distributed inland. The contamination is not only soluble salt, but more of a mixture of soluble and insoluble substances. The spraying method is only applicable to soluble salt solutions and cannot mix insoluble substances. However, the solid layer method uses brushing for contamination, and the properties of the solution are not affected. Insoluble substances can be mixed. Compared with the spraying method, it is closer to the actual situation, and the experimental data is more real and reliable.

[0022] 2. The present invention uses an artificial climate chamber to simulate low air pressure. As the altitude changes, the air pressure also changes. Currently, most studies only study the impact of a single altitude, and do not study the impact of a series of altitude changes. The artificial climate chamber can be used to simulate the air pressure conditions at different altitudes, thereby simulating the DC pollution flashover conditions under different air pressure environments, which can provide more reliable data for DC pollution flashover in different regions;

[0023] 3. The present invention utilizes a uniform voltage boost method to perform a pressure test on the sample. Compared with the constant voltage test method, the uniform voltage boost method can gradually increase the voltage, thereby avoiding equipment damage or personnel safety risks caused by excessive voltage changes. At the same time, this method is relatively easy to operate and can obtain the dirty flashover voltage of the sample within a relatively small test cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the test steps in the embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1:

[0027] Please refer to the attached Figure 1 The present invention provides a low-pressure insulating bracket DC flashover test device and method, the following steps:

[0028] Step 1: Pretreatment of the sample. To avoid test errors caused by the original dirt on the sample surface, the sample needs to be cleaned before the dirt test. The specific steps are: use anhydrous ethanol solution to remove lipid substances and other dirt residues, then wash the sample surface with clean water, and then let it stand until the sample surface is dry;

[0029] Step 2: Pollution method of the sample. Although the composition of natural pollution is complex, it can be generally divided into two categories: soluble and insoluble. In the flashover process, the main function of insoluble matter is to absorb water and moisten the pollution layer. Soluble matter forms conductive ions after dissolving in water, which affects the surface insulation strength. Use NaCl to simulate the soluble matter in the pollution, and use highly absorbent diatomaceous earth, kaolin and other materials to simulate the insoluble matter in the pollution. The two are weighed in proportion, and deionized water is added to make a sewage liquid and applied to the surface of the sample. After it dries, add artificial mist to moisten it, and apply a test voltage;

[0030] Step 3: Dry the sample in the shade. After artificial contamination, the sample should be left to stand for 24 hours to allow the surface dirt to dry. During this period, care should be taken to prevent dirt from the environment from settling on the sample surface, which could cause test errors.

[0031] Step 4: Create a low-pressure environment. For the convenience of engineering applications, the air pressure is usually directly linked to the altitude. The test sample is placed in an artificial climate laboratory. After the artificial climate laboratory is completely sealed, start pumping until the target air pressure is reached. During the process of pumping air pressure, the pumping speed should be sufficient to prevent condensation on the surface of the test sample.

[0032] Step 5: Wetting of the test piece. The dirt layer of the test piece insulator is moistened by adding steam mist to the climate chamber. The steam mist can be provided by a boiler. The vent holes are located in the corners around the climate chamber. The test piece is placed in the center of the climate chamber so that the jet distance is far enough to meet the test requirements. At the same time, the test environment temperature should be within the range of 30 to 35 degrees Celsius. Affected by the hot mist, the indoor ambient temperature rises. When the ambient temperature exceeds this range, it should be adjusted through the refrigeration system. Since the test environment is in a low-pressure state, when the valve is opened to let in hot mist, the air pressure in the artificial climate chamber will increase. In order to maintain the air pressure at a predetermined value, the exhaust equipment should be turned on during the introduction of hot mist, thereby ensuring that the flashover test can be carried out immediately when the test piece is fully moistened, thereby improving the accuracy of the test results;

[0033] Step 6: Pressurization operation method. Start pressurizing for flashover test when fully wetted. The pressurization method is uniform pressure increase method. In order to improve accuracy and reduce test errors, repeated tests are required. The implementation method is: 3 to 5 test pieces are contaminated at one degree of contamination, and a single test piece flashes 4 to 5 times. After each flashover test, the results are recorded. Among the results obtained, the average value of the test results with a relative error of less than 10% is taken as the flashover voltage.

[0034] Specific work flow: pre-treat the sample, clean it with tap water and alcohol, wrap it with plastic cloth after drying, seal it for later use, and gently and evenly apply a layer of dry diatomaceous earth on the surface of the sample with a dry sponge or soft brush, and then use an air blowing device such as an ear bulb to blow off the excess diatomaceous earth on the surface, so that a very thin layer of hydrophilic substance is attached to the surface of the insulator; carry out pollution treatment on the sample, the pollution degree of the sample is expressed by salt density and ash density, calculate the surface area of ​​the sample, calculate the amount of sodium chloride and insoluble inert substances required for each sample according to the required salt density and ash density, and then add an appropriate amount of deionized water, stir it evenly, and evenly brush it on the surface of the sample; dry the sample in the shade, put the contaminated sample in a cool place to dry, avoid direct sunlight, and let it stand for 24 hours to wait for the surface pollution layer to dry. During the drying period, the sample should be protected to avoid the pollution of the environment. The test sample is affected; the low-pressure environment is generated by placing the test sample in an artificial climate chamber, making sure that the climate chamber where the test sample is located is in a closed state, and the climate chamber is evacuated using the program setting to achieve the set low-pressure environment. During the evacuation process, the evacuation speed is controlled by adjusting the height rise rate; the test sample is moistened by using the steam mist in the climate chamber. The jet nozzle should be far enough away from the test sample to prevent steam from cleaning the surface of the test sample. At the same time, the temperature in the climate chamber should not be too high. When the temperature is too high, the refrigeration system should be used to cool the climate chamber environment until a continuous water film appears on the surface of the test sample and does not drip down; the test sample is pressurized, and when the moistening is completed, a voltage is applied to the test sample. The voltage to the test sample is gradually increased using the uniform voltage-boosting method. To avoid errors, the test sample is pressurized multiple times, and the results with a relative error of less than 10% are averaged to obtain the pollution flashover voltage.

[0035] Embodiment 2:

[0036] Based on the first embodiment, please refer to the attached Figure 1 As shown, in step 2, the solid layer method is used to simulate contamination, NaCl is used to simulate soluble matter, and kaolin is used to simulate insoluble matter. The ratio of soluble matter to insoluble matter is 1:4, and a 10% margin should be added when mixing the solution. The contamination should be completed within 1 hour after the sample is pretreated; in step 4, the air pressure p is used as a characteristic quantity of the influence of atmospheric parameters on the discharge voltage, and its relationship with the altitude H can be expressed as:

[0037]

[0038] Where: p0 is the air pressure under standard atmospheric pressure, 101.3kPa. During the process of pumping out the air pressure, the pumping speed should be sufficient to prevent condensation on the surface of the insulator, and the pumping speed should be controlled at a height change rate of 5m / s; in step six, the uniform boosting method boosting rate is 1kV / s, and the average pollution flashover voltage and relative standard deviation can be expressed as:

[0039]

[0040] Where: U f Indicates the average pollution flashover voltage of the insulator; U fi represents the i-th pollution flashover voltage; N represents the number of tests; σ% represents the relative standard deviation of the test results.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-pressure insulation bracket DC pollution flashover test device and method, characterized in that: The following steps are involved: Step 1: Pretreatment of the sample. To avoid test errors caused by the original dirt on the sample surface, the sample needs to be cleaned before the dirt test. The specific steps are: use anhydrous ethanol solution to remove lipid substances and other dirt residues, then wash the sample surface with clean water, and then let it stand until the sample surface is dry; Step 2: Pollution method of the sample. Although the composition of natural pollution is complex, it can be generally divided into two categories: soluble and insoluble. In the flashover process, the main function of insoluble matter is to absorb water to moisten the pollution layer. Soluble matter forms conductive ions after dissolving in water, which affects the surface insulation strength. Use NaCl to simulate the soluble matter in the pollution, and use highly absorbent materials such as diatomaceous earth and kaolin to simulate the insoluble matter in the pollution. Weigh the two in proportion, add deionized water to make a sewage liquid and apply it on the surface of the sample. After it dries, add artificial mist to moisten it, and apply a test voltage. Step 3: Dry the sample in the shade. After artificial contamination, the sample should be left to stand for 24 hours to allow the surface dirt to dry. During this period, care should be taken to prevent dirt from the environment from settling on the sample surface, which could cause test errors. Step 4: Create a low-pressure environment. For the convenience of engineering applications, the air pressure is usually directly linked to the altitude. The test sample is placed in an artificial climate laboratory. After the artificial climate laboratory is completely sealed, start pumping until the target air pressure is reached. During the process of pumping air pressure, the pumping speed should be sufficient to prevent condensation on the surface of the test sample. Step 5: Wetting of the test piece. The dirt layer of the test piece insulator is moistened by adding steam mist to the climate chamber. The steam mist can be provided by a boiler. The vent holes are located in the corners around the climate chamber. The test piece is placed in the center of the climate chamber so that the jet distance is far enough to meet the test requirements. At the same time, the test environment temperature should be within the range of 30 to 35 degrees Celsius. Affected by the hot mist, the indoor ambient temperature rises. When the ambient temperature exceeds this range, it should be adjusted through the refrigeration system. Since the test environment is in a low-pressure state, when the valve is opened to let in hot mist, the air pressure in the artificial climate chamber will increase. In order to maintain the air pressure at a predetermined value, the exhaust equipment should be turned on during the introduction of hot mist, thereby ensuring that the flashover test can be carried out immediately when the test piece is fully moistened, thereby improving the accuracy of the test results; Step 6: Pressurization operation method. Start pressurizing for flashover test when fully wetted. The pressurization method is uniform pressure increase method. In order to improve accuracy and reduce test errors, repeated tests are required. The implementation method is: 3 to 5 test pieces are contaminated at one degree of contamination, and a single test piece flashes 4 to 5 times. After each flashover test, the results are recorded. Among the results obtained, the average value of the test results with a relative error of less than 10% is taken as the flashover voltage.

2. A low-pressure insulating bracket DC flashover test device and method according to claim 1, characterized in that: In the step 2, the commonly used contamination methods in the artificial pollution test include salt spray method and solid layer method. The salt spray method uses a salt solution to simulate pollution. The salt solution is prepared with NaCl and deionized water according to the required salinity, and then the prepared salt solution is atomized by compressed air, and the salt spray is sprayed on the test sample through a nozzle. This contamination method is mainly used to simulate the operating environment of coastal areas. my country's low-pressure areas are inland, so it is not suitable to use the salt spray method. The solid layer method is used to simulate pollution, using NaCl to simulate soluble substances and kaolin to simulate insoluble substances. The ratio of soluble substances to insoluble substances is 1:4, and a 10% margin should be added when mixing the solution of soluble substances and insoluble substances. The contamination should be completed within 1 hour after the pretreatment of the test sample.

3. A low-pressure insulating support DC flashover test device and method according to claim 1, characterized in that: In step 4, the air pressure p is used as a characteristic quantity of the influence of the atmospheric parameters on the discharge voltage, and its relationship with the altitude H can be expressed as: Where: p0 is the air pressure under standard atmospheric pressure, 101.3kPa. During the process of pumping air, the pumping speed should be sufficient to prevent condensation on the surface of the insulator, and the pumping speed should be controlled at a height change rate of 5m / s.

4. A low-pressure insulating support DC flashover test device and method according to claim 1, characterized in that: In step 5, the wetness characteristic of the sample surface should be a continuous water film without dripping down.

5. A low-pressure insulating support DC flashover test device and method according to claim 1, characterized in that: In step 6, the uniform boosting method has a boosting rate of 1 kV / s, and the average pollution flashover voltage and relative standard deviation can be expressed as: Where: U f Indicates the average pollution flashover voltage of the insulator; U fi represents the i-th pollution flashover voltage; N represents the number of tests; σ% represents the relative standard deviation of the test results.

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