Device and method for evaluating gas insulation performance

Abstract

The invention provides a gas insulation performance evaluation device and method. Comprising a reaction chamber in a vacuum state; the electron beam generating unit is used for generating electron beams; the scattering chamber is arranged in the reaction cavity, and insulating gas is arranged in the scattering chamber; the electron beam energy measuring unit is used for measuring the energy of the electron beam; and the electron beam regulation and control unit comprises a direction regulation and control unit and a speed regulation and control unit which are respectively used for controlling the direction and the speed of the electron beam.

Description

Technical Field

[0001] The invention belongs to the field of insulating gas evaluation, and in particular relates to a device and method for evaluating gas insulation performance. Background Art

[0002] As the global awareness of environmental protection increases, the application of traditional high greenhouse effect gases such as SF6 in the power industry has been strictly restricted. Therefore, finding and developing new insulating gases with excellent insulation properties and environmental protection characteristics has become an important research direction in the power industry.

[0003] Traditional insulation performance evaluation methods mainly rely on breakdown voltage testing, which is to test the insulation strength of the gas by applying a high voltage. However, this method can only provide limited insulation performance information and cannot fully reflect the electron scattering characteristics of the gas. In order to evaluate the insulation performance of these new environmentally friendly insulating gases, an accurate and reliable test platform and method are needed. Summary of the invention

[0004] The present invention provides a gas insulation performance evaluation device and method, which can more comprehensively evaluate the insulation performance of the reaction gas.

[0005] In one aspect, a gas insulation performance evaluation device is provided, comprising: A reaction chamber, the interior of which is in a vacuum state; An electron beam generating unit, used for generating an electron beam; A scattering chamber is arranged in the reaction chamber, and an insulating gas is contained in the scattering chamber; An electron beam energy measuring unit, used for measuring the energy of the electron beam; The electron beam control unit includes a direction control unit and a speed control unit, which are used to control the direction and speed of the electron beam respectively.

[0006] Optionally, the electron beam generating unit comprises a cathode ray tube.

[0007] Optionally, the electron beam energy measuring unit includes a delay potential analyzer and a Faraday cup.

[0008] Optionally, the direction control unit includes: A first magnet and a second magnet, wherein the first magnet is arranged around the scattering chamber to control the direction of the electron beam after scattering in the scattering chamber; and the second magnet is arranged around the electron beam energy measuring unit to correct the direction of the electron beam.

[0009] Optionally, the magnetic induction intensity of the first magnet and the second magnet is 450~500Gs.

[0010] Optionally, the speed control unit comprises one or more accelerating electrodes.

[0011] Optionally, the pressure in the reaction chamber is 1×10 -8 ~1×10 -9 torr.

[0012] Optionally, it also includes: The pressure monitoring unit, the pressure regulating unit and the control unit are used to control the pressure regulating unit to regulate the pressure in the reaction chamber according to the pressure in the reaction chamber obtained by the pressure detection unit.

[0013] In another aspect, a method for evaluating gas insulation performance is provided, comprising: emitting an electron beam with initial energy toward the gas to be evaluated; After the electron beam passes through the gas to be evaluated, the energy of the electron beam is obtained; The total electron scattering cross section of the gas to be evaluated is determined based on the energy difference before and after the electron beam passes through the gas to be evaluated, and the insulation performance of the gas to be evaluated is determined based on the total electron scattering cross section.

[0014] Optionally, the total electron scattering cross section is calculated as follows:

[0015] in, is the total electron scattering cross section, is the target particle number density, is the scattering element length, is the normalized scattered current value of the electron beam after passing through the gas to be evaluated.

[0016] The technical solution provided by the present invention has the following beneficial effects: The present invention provides a gas insulation performance evaluation device, which includes a reaction chamber, an electron beam generating unit, a scattering chamber, an electron beam energy measuring unit and an electron beam regulating unit. The electron beam is generated by the electron beam generating unit, and under the action of the electron beam regulating unit, the electron beam is shot into the scattering chamber at a certain speed and a certain direction, and collides with the gas to be evaluated in the scattering chamber. After the collision, the electrons in the electron beam are re-regulated by the electron beam regulating unit and then emitted from the scattering chamber. The reaction chamber is in a vacuum state, so the energy loss of the electron beam is mainly caused by the collision with the gas to be evaluated. By evaluating the energy loss of the electron beam, the size of the total electron scattering cross section of the gas to be evaluated can be calculated. By determining the size of the total electron scattering cross section of the gas to be evaluated and the standard insulating gas under a certain electron beam generating voltage, the difference in insulation performance between the gas to be evaluated and the standard insulating gas can be determined.

[0017] By measuring the scattering cross section between electrons and environmentally friendly insulating gas molecules, the structure and properties of gas molecules can be indirectly reflected, thereby evaluating their insulating performance. This method uses the total electron scattering cross section as a new indicator for evaluating the insulating performance of environmentally friendly insulating gases, providing a new perspective and idea for the evaluation of insulating performance. The test platform uses advanced measurement technology and equipment to accurately measure the total electron scattering cross section to ensure the accuracy and reliability of the evaluation results. High-precision measurements help to discover tiny changes in insulation performance and provide strong support for further optimization and improvement of environmentally friendly insulating gases. This method is suitable for the evaluation of a variety of environmentally friendly insulating gases, including but not limited to new environmentally friendly insulating gases such as nitrogen and dry air. By adjusting the test conditions, the insulation performance requirements in different application scenarios can be simulated to provide a comprehensive evaluation for the application of environmentally friendly insulating gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic structural diagram of a gas insulation performance evaluation device provided by the present invention.

[0020] Figure 2 A control flow chart of a control unit provided in this embodiment.

[0021] Figure 3 A flow chart of a method for evaluating gas insulation performance provided by the present invention.

[0022] Figure 4 An experimental schematic diagram provided for this embodiment.

[0023] The reference numerals are as follows: 1: reaction chamber; 11: inlet; 12: outlet; 2: Electron beam generating unit; 3: Scattering chamber; 4: electron beam energy measurement unit; 41: first delay potential analyzer; 42: first delay potential analyzer; 43: Faraday cup; 5: electron beam control unit; 51: direction control unit; 511: first magnet; 512: second magnet; 52: speed control unit; 6: Pressure monitoring unit; 7: Pressure control unit; 8: Control unit. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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.

[0025] Figure 1 This is a schematic diagram of the structure of a gas insulation performance evaluation device provided by the present invention. Figure 1 ,include: A reaction chamber 1, which is in a vacuum state; An electron beam generating unit 2, used for generating an electron beam; A scattering chamber 3, arranged in the reaction chamber, wherein the scattering chamber contains insulating gas; An electron beam energy measuring unit 4, used for measuring the energy of the electron beam; The electron beam control unit 5 comprises a direction control unit 51 and a speed control unit 52, which are used to control the direction and speed of the electron beam respectively.

[0026] The present invention provides a gas insulation performance evaluation device, which includes a reaction chamber, an electron beam generating unit, a scattering chamber, an electron beam energy measuring unit and an electron beam regulating unit. The electron beam is generated by the electron beam generating unit, and under the action of the electron beam regulating unit, the electron beam is shot into the scattering chamber at a certain speed and a certain direction, and collides with the gas to be evaluated in the scattering chamber. After the collision, the electrons in the electron beam are re-regulated by the electron beam regulating unit and then emitted from the scattering chamber. The reaction chamber is in a vacuum state, so the energy loss of the electron beam is mainly caused by the collision with the gas to be evaluated. By evaluating the energy loss of the electron beam, the size of the total electron scattering cross section of the gas to be evaluated can be calculated. By determining the size of the total electron scattering cross section of the gas to be evaluated and the standard insulating gas under a certain electron beam generating voltage, the difference in insulation performance between the gas to be evaluated and the standard insulating gas can be determined.

[0027] By measuring the scattering cross section between electrons and environmentally friendly insulating gas molecules, the structure and properties of gas molecules can be indirectly reflected, thereby evaluating their insulating performance. This method uses the total electron scattering cross section as a new indicator for evaluating the insulating performance of environmentally friendly insulating gases, providing a new perspective and idea for the evaluation of insulating performance. The test platform uses advanced measurement technology and equipment to accurately measure the total electron scattering cross section to ensure the accuracy and reliability of the evaluation results. High-precision measurements help to discover tiny changes in insulation performance and provide strong support for further optimization and improvement of environmentally friendly insulating gases. This method is suitable for the evaluation of a variety of environmentally friendly insulating gases, including but not limited to new environmentally friendly insulating gases such as nitrogen and dry air. By adjusting the test conditions, the insulation performance requirements in different application scenarios can be simulated to provide a comprehensive evaluation for the application of environmentally friendly insulating gases.

[0028] In this embodiment, the pressure in the reaction chamber 1 is 1×10 -8 ~1×10 -9 torr.

[0029] For example, the pressure in the reaction chamber 1 is 1×10 -9 torr.

[0030] In this embodiment, the reaction chamber 1 includes an inlet 11 and an outlet 12 .

[0031] In this embodiment, ensuring that the pressure in the reaction chamber is sufficiently large can ensure that the error of the total electron scattering cross section measured in the final experiment is small.

[0032] In this embodiment, the electron beam generating unit 2 includes a cathode ray tube. By using the cathode ray tube as an electron source, a high-energy electron beam is generated.

[0033] In the present embodiment, the electron beam energy measuring unit 4 includes a delay potential analyzer 41 and a Faraday cup 42 .

[0034] exist Figure 1 In the embodiment, a first delay potential analyzer 41 and a second delay potential analyzer 42 are included, wherein the first delay potential analyzer 41 is arranged between the scattering chamber 3 and the speed control unit 51, and the second delay potential analyzer 42 is arranged between the scattering chamber 3 and the electron beam energy measurement unit 4.

[0035] The first delay potential analyzer and the second delay potential analyzer are designed to act as a coarse grating by removing the low energy part of the incident electron beam. The second delay potential analyzer also acts as an energy analyzer, which is only sensitive to the energy component parallel to the incident electron beam axis (or magnetic field direction). The cross-sectional measurement result can be obtained by analyzing the energy distribution. The Faraday cup 43 is used to measure the electron current.

[0036] In this embodiment, the direction control unit 51 includes: The first magnet 511 and the second magnet 512 are arranged around the scattering chamber 3 to control the direction of the electron beam after scattering in the scattering chamber 3; the second magnet is arranged around the electron beam energy measuring unit 4 to correct the direction of the electron beam.

[0037] In this embodiment, the electron beam has a certain direction after being emitted from the electron beam generating unit. However, after passing through the scattering chamber 3 and the electron beam energy measuring unit 4, its direction may deviate. By setting a direction control unit 51, the direction of the electron beam can be corrected.

[0038] In this embodiment, the magnetic induction intensity of the first magnet 511 and the second magnet 512 is 450-500 Gs.

[0039] Exemplarily, the magnetic induction intensity of the first magnet 511 and the second magnet 512 is 470 Gs.

[0040] In this embodiment, the first magnet 511 and the second magnet 512 adopt magnetic induction intensities within the above range, which can ensure that the first magnet and the second magnet can better control the direction of the electron beam.

[0041] In this embodiment, the speed control unit 52 includes one or more accelerating electrodes. By increasing the speed of the electron beam through the speed control unit, the measurement efficiency can be improved.

[0042] In this embodiment, the device further includes: a pressure monitoring unit 6, a pressure regulating unit 7 and a control unit 8, which is used to control the pressure regulating unit 7 to regulate the pressure in the reaction chamber 1 according to the pressure in the reaction chamber 1 obtained by the pressure detection unit 6.

[0043] The pressure monitoring unit 6 includes a Baratron vacuum gauge, and the pressure regulating unit 7 includes a turbomolecular pump. Two turbomolecular pumps may be provided, respectively at the inlet and the outlet of the reaction chamber.

[0044] In this embodiment, a pressure monitoring unit, a pressure regulating unit and a control unit are provided to ensure that the pressure in the reaction chamber meets the requirements, thereby avoiding a pressure drop in the reaction chamber during the experiment, which results in a low accuracy of the measured total electron scattering cross section.

[0045] Figure 2 A control flow chart of a control unit provided in this embodiment, wherein the vacuum system is a pressure regulating unit, and the control method is implemented by a LabVIEW program.

[0046] First, initialize the LabVIEW environment. Configure all hardware interfaces (such as Faraday cup, Baratron vacuum gauge, turbomolecular pump, etc.). Set measurement parameters (such as magnetic field strength, target gas pressure, etc.). Then start two independent turbomolecular pumps: Monitor the ultimate pressure of the two vacuum regions to ensure that it reaches about 1 × 10^-9 Torr. Adjust the electron beam through the electron lens. Ensure that the electron beam passes through a series of electrodes, scattering cells, and delay potential analyzer. Monitor the target gas pressure using a Baratron vacuum gauge (MKS 628B). Maintain the target gas pressure of about 0.5 mTorr during the measurement. Inject target gas into the scattering cell as needed. Monitor the system stability after gas injection. After the system is stable, measure the electron current through the Faraday cup. Perform measurements with and without target gas collisions. Record all measurement data (such as electron current, target gas pressure, magnetic field strength, etc.). Ensure the accuracy and completeness of the data. Finally, analyze the recorded data to extract key information. Generate a report or chart to present the measurement results.

[0047] Figure 3 A flow chart of a method for evaluating gas insulation performance provided by the present invention. Figure 3 ,include: S101, emitting an electron beam with initial energy toward a gas to be evaluated.

[0048] S102, after the electron beam passes through the gas to be evaluated, obtaining the energy of the electron beam.

[0049] S103, determining the size of the total electron scattering cross section of the gas to be evaluated according to the energy difference before and after the electron beam passes through the gas to be evaluated, and determining the insulation performance of the gas to be evaluated according to the size of the total electron scattering cross section.

[0050] In step S103, the calculation formula of the total electron scattering cross section is as follows:

[0051] in, is the total electron scattering cross section, is the target particle number density, is the scattering element length, is the normalized scattered current value of the electron beam after passing through the gas to be evaluated.

[0052] In this example, the total electron scattering cross section is determined from the current measured by the Faraday cup.

[0053] The principles of the gas insulation performance evaluation device and method provided by the present invention are as follows: The total electron scattering cross section measurement is based on the attenuation of a monoenergetic electron beam transmitted through a target volume of gas at constant pressure and temperature. In an ideal transmission experiment, the attenuation of the electron beam through the gas cell at different electron energy levels is related to the properties of the target gas, which can be derived from the Beer–Lambert law for light attenuation.

[0054] In this embodiment, the Beer–Lambert law of light attenuation is used to obtain:

[0055] in, and Indicates the current intensity of the electron beam with or without target gas in the scattering cell.

[0056] Then, the above formula is transformed to obtain the calculation formula of the total electron scattering cross section.

[0057] Figure 4 This is a schematic diagram of an experiment provided in this embodiment. Figure 4 , in such Figure 1 The current of the electron beam obtained when the gas to be evaluated is passed through and when the gas to be evaluated is not passed through the device for evaluating gas insulation performance is shown in the figure. It can be determined that the gas to be evaluated will react with the electron beam, thereby consuming a part of the energy of the electron beam.

[0058] The present invention also provides some specific test case embodiments: The total electron scattering cross section of C3F6O gas was measured in the energy range between 15 eV and 90 eV. The measurement revealed some characteristics in the electron energy range: first, a sharp increase in the total electron scattering cross section between 15 eV and 30 eV, second, the highest total electron scattering cross section value at 30 eV, and finally a gradual decrease in the total electron scattering cross section between 30 eV and 90 eV. The total electron scattering cross section values ​​for 15 eV, 30 eV, and 90 eV electron collisions are 8.2×10 −16 cm 2 , 20.8×10 −16 cm 2 and 15.8×10 −16 cm 2 The sharp increase in features below 30 eV is related to the ionization process. The most abundant positive ion is CF3 + , whose ionization threshold energy is 11.8eV. The ionization efficiency rises rapidly to 50eV and then reaches a stable period. Since the total electron scattering cross section measurement starts from 15eV, we believe that CF3 + Part of the ionization is related to this sharp increase. The most abundant anion is CF3O− , produced by the attachment of dissociated electrons between 1.5eV and 5.5eV.

[0059] The insulation performance of SF6 and C3F6O can be evaluated by comparing their stable negative ion formation. As an insulating gas, the formation of stable negative ions is one of the essential requirements. For SF6, the main stable negative ions formed by total electron attachment below about 0.2eV are SF6 − SF6 − It has an octahedral structure and is a structurally stable negative ion, so it is suitable as an insulating gas. Due to its strong stable negative ion structure, it has been used as an insulating gas for a long time. From this point of view, it is necessary to study the formation of stable negative ions by electron collision of C3F6O. For C3F6O, CF3O − It is formed by the dissociative electron attachment (DEA) process at 1.5~5.5eV, and CF3O at 2.5 eV − The strength of this negative ion is particularly high. The structure of this negative ion is a stable tetrahedral structure. Another possible negative ion is similar to SF6, which is F − ions, but their intensity is much lower than that of CF3O − Therefore, the main DEA process product, stabilized C3F6O, has the potential to serve as an alternative to SF6 gas as an insulating gas.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas insulation performance evaluation device, characterized in that: include: A reaction chamber, the interior of which is in a vacuum state; An electron beam generating unit, used for generating an electron beam; A scattering chamber is arranged in the reaction chamber, and an insulating gas is contained in the scattering chamber; An electron beam energy measuring unit, used for measuring the energy of the electron beam; The electron beam control unit includes a direction control unit and a speed control unit, which are used to control the direction and speed of the electron beam respectively.

2. The gas insulation performance evaluation device according to claim 1, characterized in that: The electron beam generating unit includes a cathode ray tube.

3. The gas insulation performance evaluation device according to claim 1, characterized in that: The electron beam energy measurement unit includes a delay potential analyzer and a Faraday cup.

4. The gas insulation performance evaluation device according to claim 1, characterized in that: The direction control unit comprises: A first magnet and a second magnet, wherein the first magnet is arranged around the scattering chamber to control the direction of the electron beam after scattering in the scattering chamber; and the second magnet is arranged around the electron beam energy measuring unit to correct the direction of the electron beam.

5. The gas insulation performance evaluation device according to claim 4, characterized in that: The magnetic induction intensity of the first magnet and the second magnet is 450-500 Gs.

6. The gas insulation performance evaluation device according to claim 1, characterized in that: The speed control unit includes one or more accelerating electrodes.

7. The gas insulation performance evaluation device according to claim 1, characterized in that: The pressure in the reaction chamber is 1×10 -8 ~1×10 -9 torr.

8. The gas insulation performance evaluation device according to claim 1, characterized in that: Also includes: The pressure monitoring unit, the pressure regulating unit and the control unit are used to control the pressure regulating unit to regulate the pressure in the reaction chamber according to the pressure in the reaction chamber obtained by the pressure detecting unit.

9. A method for evaluating gas insulation performance, characterized in that: include: emitting an electron beam with initial energy toward the gas to be evaluated; After the electron beam passes through the gas to be evaluated, the energy of the electron beam is obtained; The total electron scattering cross section of the gas to be evaluated is determined based on the energy difference before and after the electron beam passes through the gas to be evaluated, and the insulation performance of the gas to be evaluated is determined based on the total electron scattering cross section.

10. The method for evaluating gas insulation performance according to claim 9, characterized in that: The total electron scattering cross section is calculated as follows: in, is the total electron scattering cross section, is the target particle number density, is the scattering element length, is the normalized scattered current value of the electron beam after passing through the gas to be evaluated.

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