Method and system for screening environmentally friendly insulating gases for electrical equipment based on electron swarm parameters

Abstract

The application discloses a kind of screening method and system of environmental protection insulating gas for electrical equipment based on electron group parameter, comprising: constructing the candidate database of environmental protection insulating gas;Based on the theory of tompson discharge, tompson discharge experimental system is constructed;For each insulating gas in candidate database, tompson discharge experiment is carried out;The tompson discharge experiment is under the condition of set gas pressure and interval, changes the electric field intensity applied, obtains ionization coefficient and adsorption coefficient under different reduced field intensity, obtains the effective ionization coefficient and critical breakdown field strength of corresponding insulating gas based on the ionization coefficient and adsorption coefficient;According to the relationship between the effective ionization coefficient of the insulating gas and electric field and gas pressure, the power frequency insulation strength of the insulating gas is obtained;Based on the critical breakdown field strength and power frequency insulation strength of the insulating gas, the insulating gas meeting the preset performance index is screened out from the candidate database.The defects of low efficiency or unclear physical mechanism of traditional method are overcome.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly gas power transmission and transformation equipment technology, specifically to a method and system for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters. Background Technology

[0002] Sulfur hexafluoride (SF6) gas is widely used in power transmission and transformation equipment due to its excellent electrical properties. However, SF6 has a greenhouse effect 24,300 times that of CO2 and an atmospheric lifetime of up to 1,000 years, making it a prohibited and restricted greenhouse gas under international conventions such as the Kyoto Protocol. Domestic and international research indicates that environmentally friendly gases such as perfluoroisobutyronitrile (C4F7N) and trifluoromethanesulfonyl fluoride (CF3SO2F), as well as their mixtures with CO2 and N2, have high insulation strength and low greenhouse effect, making them potential alternatives to SF6. Compared to SF6, environmentally friendly gases such as C4F7N or CF3SO2F are newly developed synthetic gases in the last 10 years, and their key properties, such as insulation strength, are still under continuous research. In particular, there is currently no standardized environmentally friendly gas internationally recognized as a substitute for SF6 in electrical equipment. Therefore, the development of high-performance new environmentally friendly insulating gases and their mixtures is still ongoing. The selection of novel environmentally friendly insulating gases or environmentally friendly mixed gases suitable for electrical equipment should first obtain the most critical basic insulation performance. Faced with the challenges of evaluating and comparing the insulation strength of different gases, as well as the influence of related factors on the gas insulation performance, it is necessary to develop environmentally friendly insulating gas screening methods and systems based on electron group parameters.

[0003] Currently, the screening methods for environmentally friendly insulating gases mainly include the following two categories: (1) Experimental trial and error method This method involves placing flat electrodes with varying gap distances in a sealed cavity and conducting power frequency discharge tests under different gas pressures, mixing ratios, and gap distances to obtain insulation strength data for different environmentally friendly mixed gases. However, this method requires a large amount of experimental work and makes it difficult to exhaust all parameter combinations. Furthermore, the experimental results are easily affected by factors such as the number of tests, electrode surface condition, and gas filling process, resulting in significant deviations. Overall, this method is costly, time-consuming, and requires complex physical experiments for each verification, making it extremely inefficient.

[0004] (2) Molecular structure simulation method This method utilizes quantum chemical calculations to obtain static parameters such as molecular polarizability and electron affinity, and employs machine learning to construct a model relating structure and insulation properties, thereby enabling the prediction of gas properties. However, this method focuses on calculating static molecular properties and struggles to dynamically simulate the physical mechanisms involved in the entire process of gas breakdown under an electric field, from the initiation of discharge to breakdown. This often leads to discrepancies between the screening results and actual engineering practices.

[0005] The essence of gas insulation performance lies in its ability to suppress discharge development. According to Townshend discharge theory, whether a gas gap breaks down depends on the development process of electron avalanches, where the ionization coefficient is a key parameter describing the electron ionization capability. For electronegative gases, there is also an adsorption coefficient, and both together determine the effective ionization coefficient of the gas. When the effective ionization coefficient is greater than 0, electron avalanches grow, and the gap is prone to breakdown; when the effective ionization coefficient is less than or equal to 0, the ionization process is suppressed, and the gas remains in an insulating state. Therefore, the reduced field strength at which the effective ionization coefficient reaches zero is the critical breakdown field strength, which is a direct physical quantity for measuring the insulation strength of a gas. Therefore, how to directly screen environmentally friendly gases with high insulation strength from the electron group behavior level by measuring the ionization and adsorption characteristics of gases is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters, comprising: Construct a candidate database of environmentally friendly insulating gases; Based on Townsend discharge theory, a Townsend discharge experimental system was constructed. Based on the Townsend discharge experimental system, Townsend discharge experiments are conducted for each insulating gas in the candidate database. Under the conditions of set gas pressure and spacing, the applied electric field strength is changed to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained. The power frequency insulation strength of the insulating gas is obtained based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure. Based on the critical breakdown field strength and power frequency insulation strength of the insulating gas, insulating gases that meet the preset performance indicators are selected from the candidate database.

[0007] Furthermore, a candidate database of environmentally friendly insulating gases includes: Perfluoroisobutyronitrile (C4F7N), perfluoropentanone (C5F) 10 O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases (HFO1234ze), insulating gases, and binary or ternary mixtures of gases with CO2, N2, and O2 natural gases.

[0008] Furthermore, the Townsend discharge experimental system is as follows: Two flat copper electrodes with Bruce profiles form a uniform electric field; ultraviolet light is generated by a vacuum ultraviolet light source (UV) embedded in the vacuum chamber, which irradiates the coated glass surface embedded in the center of the photocathode, exciting the initial electrons. A high DC voltage is applied between flat copper electrodes, and the initial electrons are accelerated in the DC electric field. The accelerated electrons interact with gas molecules. Various collision reactions occur between the gas molecules, among which ionization and adsorption reactions affect the number of electrons, and the number of electrons affects the magnitude of the current in the gas. By measuring the discharge current of the external circuit, the ionization and adsorption coefficients of the gas discharge are obtained by inversion.

[0009] Furthermore, the Townshend discharge experiment, under set gas pressure and spacing conditions, varies the applied electric field strength to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained, including: Set air pressure p 1 and spacing d Under certain conditions, change the applied electric field strength E To obtain different reduced field strengths E r ionization coefficient at the bottom α and adsorption coefficient η ; Based on the ionization coefficient α and adsorption coefficient η Obtain the effective ionization coefficient of the corresponding insulating gas = α - η ; In the Townsend discharge experiment, an initial photoelectron current is generated by continuously irradiating the photocathode with ultraviolet light. I 0. Under a uniform electric field, neglecting the secondary process, the discharge current in the circuit is 0. I Spacing d The relationship is: (1) Let the air pressure be p 1. Change the spacing d Measure different d Discharge current in the lower experimental circuit I Substituting into equation (1), we obtain different E r Below α and η ,when When = 0, it satisfies α = η The reduced field strength is denoted as E rc , E rc This represents the critical breakdown field strength of the insulating gas.

[0010] Furthermore, based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure, the power frequency insulation strength of the insulating gas is obtained, including: Effective ionization coefficient of insulating gas With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; (2) Transforming equation (2), we obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: (3) In the formula, E c Let be the power frequency breakdown field strength. In equation (2), =0 results in: (4) Substituting equation (4) into equation (3), we get: (5) For electronegative gases, the expression for the streamer discharge criterion is: (6) In the formula, x c The critical electron avalanche length at the start of the streamer. F It is an empirical constant in a uniform electric field. x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: (7) Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: (8) In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: (9) In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

[0011] Furthermore, based on the critical insulation strength and power frequency insulation strength of the insulating gas, insulating gases that meet preset performance indicators are screened from the candidate database, including: The critical breakdown field strength of the insulating gas E rc and power frequency insulation strength U b Using the liquefaction temperature and environmental performance indicators of candidate insulating gases as core screening indicators, insulating gases that meet the preset performance indicators are selected.

[0012] This invention also provides a screening system for environmentally friendly insulating gases for electrical equipment based on electron group parameters, comprising: The candidate database construction module is used to build a candidate database of environmentally friendly insulating gases; The Townsend discharge experimental system construction module is used to construct a Townsend discharge experimental system based on the Townsend discharge theory. The module for determining the effective ionization coefficient and critical breakdown field strength is used to conduct Townsend discharge experiments for each insulating gas in the candidate database based on the Townsend discharge experimental system. The Townsend discharge experiment changes the applied electric field strength under set gas pressure and spacing conditions to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained. The power frequency insulation strength determination module is used to obtain the power frequency insulation strength of the insulating gas based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure. An insulating gas screening module is used to screen insulating gases that meet preset performance indicators from the candidate database based on the critical breakdown field strength and power frequency insulation strength of the insulating gas.

[0013] Further, a candidate database of environmentally friendly insulating gases includes: Perfluoroisobutyronitrile (C4F7N), perfluoropentanone (C5F) 10 O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases (HFO1234ze), insulating gases, and binary or ternary mixtures of gases with CO2, N2, and O2 natural gases.

[0014] Furthermore, the Townsend discharge experimental system is as follows: Two flat copper electrodes with Bruce profiles form a uniform electric field; ultraviolet light is generated by a vacuum ultraviolet light source (UV) embedded in the vacuum chamber, which irradiates the coated glass surface embedded in the center of the photocathode, exciting the initial electrons. A high DC voltage is applied between flat copper electrodes, and the initial electrons are accelerated in the DC electric field. The accelerated electrons interact with gas molecules. Various collision reactions occur between the gas molecules, among which ionization and adsorption reactions affect the number of electrons, and the number of electrons affects the magnitude of the current in the gas. By measuring the discharge current of the external circuit, the ionization and adsorption coefficients of the gas discharge are obtained by inversion.

[0015] Furthermore, the module for determining the effective ionization coefficient and critical breakdown field strength includes: The ionization coefficient and adsorption coefficient acquisition submodule is used to set the gas pressure. p 1 and spacing d Under certain conditions, change the applied electric field strength E To obtain different reduced field strengths E r ionization coefficient at the bottom α and adsorption coefficient η ; The effective ionization coefficient acquisition submodule is used to obtain the effective ionization coefficient based on the ionization coefficient. α and adsorption coefficient η Obtain the effective ionization coefficient of the corresponding insulating gas = α - η ; The current-spacing relationship determination submodule is used to generate the initial photoelectron current in the Townsend discharge experiment by continuously irradiating the photocathode with ultraviolet light. I 0. Under a uniform electric field, neglecting the secondary process, the discharge current in the circuit is 0. I Spacing d The relationship is: (1) The critical breakdown field strength determination submodule is used to set the air pressure as follows: p 1. Change the spacing d Measure different d Discharge current in the lower experimental circuit I Substituting into equation (1), we obtain different E r Below α and η ,when When = 0, it satisfies α = η The reduced field strength is denoted as E rc , E rc This represents the critical breakdown field strength of the insulating gas.

[0016] Furthermore, the power frequency insulation strength determination module includes: The relationship determination submodule is used to determine the effective ionization coefficient of insulating gases. With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; (2) The power frequency discharge voltage acquisition submodule is used to convert equation (2) to obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: (3) In the formula, E c For the power frequency breakdown field strength, in equation (2), =0 results in: (4) Substituting equation (4) into equation (3), we get: (5) For electronegative gases, the expression for the streamer discharge criterion is: (6) In the formula, x c The critical electron avalanche length at the start of the streamer. F It is an empirical constant; in a uniform electric field, x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: (7) Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: (8) In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: (9) In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

[0017] Furthermore, the insulating gas screening module includes: a method for detecting the critical breakdown field strength of the insulating gas. E rc and power frequency insulation strength U b Using the liquefaction temperature and environmental performance indicators of candidate insulating gases as core screening indicators, insulating gases that meet the preset performance indicators are selected.

[0018] The present invention also provides a computer-readable storage medium storing a computer program for performing the method described herein.

[0019] The present invention also provides an electronic device, the electronic device comprising: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method.

[0020] This invention provides a method and system for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters. Based on Townshend discharge theory, it accurately measures the ionization and adsorption coefficients of candidate gases using steady-state Townshend or pulsed Townshend methods, and calculates their critical breakdown field strength, thereby establishing a quantitative screening system from microscopic electronic behavior to macroscopic insulation performance. The Townshend discharge experimental method is used to obtain the discharge characteristic parameters of environmentally friendly insulating gases at the mesoscopic level, and then the characterization coefficients related to the power frequency insulation strength are derived. Substituting these coefficients into the numerical simulation calculation expression of the power frequency discharge voltage of the environmentally friendly insulating gas, the normalized insulation strength of the environmentally friendly insulating gas under different gap distances, gas pressures, and mixing ratios can be obtained. This invention overcomes the shortcomings of traditional methods, such as low efficiency or unclear physical mechanisms. It reduces the number of power frequency discharge experiments and obtains the mesoscopic discharge characteristic parameters for specific environmentally friendly mixed gases, allowing for the determination of their insulation strength characterizing their physical nature in equipment on a unified basis. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of a method for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters, provided in an embodiment of the present invention. Figure 2 This refers to the structure and photocathode of the Townsend discharge experimental system involved in the embodiments of the present invention; Figure 3 These are the ionization, adsorption, and effective ionization coefficients of the insulating gas involved in the embodiments of the present invention; Figure 4 This refers to the effective ionization coefficient distribution of C4F7N and the mixed gas involved in the embodiments of the present invention; Figure 5 This refers to the effective ionization coefficient distribution of the CF3SO2F / N2 mixed gas involved in the embodiments of the present invention; Figure 6 This is a schematic diagram of a screening system for environmentally friendly insulating gases for electrical equipment based on electron group parameters, according to an embodiment of the present invention. Detailed Implementation

[0022] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0023] like Figure 1 As shown, this invention provides a method for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters, comprising the following steps: Step S101: Construct a candidate database of environmentally friendly insulating gases.

[0024] Several potential environmentally friendly insulating gas molecules were collected or virtually generated to establish a candidate database of environmentally friendly insulating gases. These candidate gases included perfluoroisobutyronitrile (C4F7N) and perfluoropentanone (C5F7N). 10 The main insulating gases include O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases HFO1234ze, and binary or ternary mixtures of these gases with natural gases such as CO2, N2, and O2.

[0025] Step S102: Based on Townsend discharge theory, construct the Townsend discharge experimental system.

[0026] A discharge experimental system based on Townsend discharge theory was constructed, which has the ability to measure the current growth of gas in the non-self-sustaining discharge stage. Figure 2 This diagram illustrates the Townsend discharge experimental system and includes a photograph of the photocathode. Two flat copper electrodes with Bruce cross-sections form a uniform electric field, with a surface roughness not exceeding 0.1 μm. Ultraviolet light, generated by a vacuum ultraviolet (UV) source embedded in the vacuum chamber, illuminates the coated glass surface embedded in the center of the photocathode, exciting initial electrons. The spectral distribution of this source ranges from 115 to 400 nm, with a peak wavelength of 160 nm. The photocathode is a crucial component in the Townsend discharge experiment, determining the effectiveness of initial electron generation. It typically employs a Rokowski electrode made of copper, with a concentric transparent quartz glass plated at its center. The surface of the glass is plated with a gold or platinum film to facilitate the photoelectric effect. The electrodes are connected to the chamber via insulating sleeves, and the spacing between the flat electrodes is adjusted using a screw-type adjustment device on the back of the anode. d .

[0027] A high DC voltage is applied between the flat electrodes. Initial electrons accelerate in the DC electric field. These accelerated electrons interact with gas molecules, leading to various collision reactions such as excitation, ionization, adsorption, and elastic collisions. Ionization and adsorption reactions directly affect the number of electrons, thus influencing the current in the gas. Due to the principle of current continuity, the current in the external circuit also changes accordingly. Therefore, by measuring the discharge current in the external circuit, the ionization and adsorption coefficients of the gas discharge can be obtained.

[0028] Step S103: Based on the Townsend discharge experimental system, a Townsend discharge experiment is performed for each insulating gas in the candidate database. The Townsend discharge experiment changes the applied electric field strength under set gas pressure and spacing conditions to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained.

[0029] use Figure 2 The experimental system was used to conduct Townsend discharge experiments on each gas in the candidate gas database at a set pressure. p 1 and spacing d Under certain conditions, change the applied electric field strength E ( E = U / d , U (For the applied DC voltage), different reduced field strengths were measured and calculated. E r ( E r = E / N , N Ionization coefficient (where is the number of electrons) α and adsorption coefficient η This leads to the effective ionization coefficient of the gas. = α - η .

[0030] In the Townsend discharge experiment, an initial photoelectron current is generated by continuously irradiating the cathode with ultraviolet light. I 0. Under a uniform electric field, if secondary processes (such as electron emission caused by positive ions bombarding the cathode) are neglected, electrons will undergo electron avalanche during their movement towards the anode, and electrons will also attach to the electronegative gas. Therefore, the discharge current in the circuit... I Spacing d The relationship is: (1) air pressure p 1 represents 0.1~0.2 MPa, changing the spacing. dThe diameter is 2 ~ 25 mm, depending on the measurement. d Discharge current in the lower experimental circuit I Substituting into equation (1), the Levenberg-Marquardt algorithm is used to solve the problem, yielding different results. E r Below α and η ,like Figure 3 As shown. When When = 0, it satisfies α = η The reduced field strength is denoted as E rc This value is the critical breakdown field strength of the gas. E rc The value is 287 Td. Figure 4 , Figure 5 The effective ionization coefficient distributions are for C4F7N and its mixture, and for CF3SO2F / N2 mixture, respectively.

[0031] Step S104: Based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure, obtain the power frequency insulation strength of the insulating gas.

[0032] Effective ionization coefficient of insulating gas With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; (2) Transforming equation (2), we obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: (3) In the formula, E c Let be the power frequency breakdown field strength. In equation (2), =0 results in: (4) Substituting equation (4) into equation (3), we get: (5) For electronegative gases, the expression for the streamer discharge criterion is: (6) In the formula, x c The critical electron avalanche length at the start of the streamer. F This is an empirical constant. In a uniform electric field,x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: (7) Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: (8) In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: (9) In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

[0033] For different gases, pressures and gap distances, the normalized chemical frequency insulation strength of environmentally friendly insulating gases can be obtained by using formula (9), which facilitates direct comparison.

[0034] Step S105: Based on the critical breakdown field strength and power frequency insulation strength of the insulating gas, select insulating gases that meet the preset performance indicators from the candidate database.

[0035] With critical insulation strength E rc and power frequency insulation strength U b Using the liquefaction temperature and environmental performance index (GWP value) of the candidate gases as the core screening indicators, the candidate gases are comprehensively ranked and selected as environmentally friendly insulating gases with excellent overall performance.

[0036] Specific application examples 1) Following step S103, Townsend discharge experiments were performed on the primary insulating gases G1 and SF6 from the candidate gas database to obtain the results for different primary insulating gases. E rcg and SF6 gas E rcs Filter out E rcg ≥ E rcs The main insulating gas is G2; 2) According to step S103, the mixed gas G formed by the main insulating gas G2 is... 2m ( k Townsend discharge experiments were conducted. k Given the molar percentage of G2 in the gas mixture, we obtain the molar percentages of different gas mixtures. E rcm Filter out E rcm ≥ E rcs mixed gas G 3m ( k ); 3) Using the power frequency insulation strength of SF6 gas at a pressure of 0.5 MPa as a reference, the power frequency discharge voltage of SF6 gas in a uniform or slightly non-uniform electric field is calculated using equation (10). U bs .

[0037] Following step (4), the set device electrode spacing d Change the air pressure of the equipment p ( p The pressure should not be less than 0.5 MPa. Calculate the gas mixture G using equation (9). 3m ( p , k power frequency discharge voltage U bg Filter out U bg ≥ U bs mixed gas G 4m ( p , k ).

[0038] 4) When the mixed gas G 4m (p, k The boiling point of the main insulating gas G4 is... T b When the unit is K, the mixture G is calculated using equation (11). 4m (p, k boiling point T bm Filter out T bm Gas mixture G ≤248 K 5m (p, k ).

[0039] 5) Mixed gas G 5m (p, k The environmental performance indicators depend on the GWP value of the main insulating gas G5, and are only related to the molar ratio of G5. k Relevant, filteredk Minimum gas mixture G 5m (p, k It is recommended as an environmentally friendly insulating gas for electrical equipment.

[0040] Based on the same inventive concept, this invention also provides a screening system 600 for environmentally friendly insulating gases used in electrical equipment based on electron group parameters, such as... Figure 6 As shown, it includes: Candidate database construction module 610 is used to construct a candidate database of environmentally friendly insulating gases; Townsend discharge experimental system construction module 620 is used to construct a Townsend discharge experimental system based on Townsend discharge theory; The effective ionization coefficient and critical breakdown field strength determination module 630 is used to perform Townsend discharge experiments for each insulating gas in the candidate database based on the Townsend discharge experimental system. The Townsend discharge experiment changes the applied electric field strength under set gas pressure and spacing conditions to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained. The power frequency insulation strength determination module 640 is used to obtain the power frequency insulation strength of the insulating gas based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure. The insulating gas screening module 650 is used to screen insulating gases that meet preset performance indicators from the candidate database based on the critical breakdown field strength and power frequency insulation strength of the insulating gas.

[0041] Further, a candidate database of environmentally friendly insulating gases includes: Perfluoroisobutyronitrile (C4F7N), perfluoropentanone (C5F) 10 O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases (HFO1234ze), insulating gases, and binary or ternary mixtures of gases with CO2, N2, and O2 natural gases.

[0042] Furthermore, the Townsend discharge experimental system is as follows: Two flat copper electrodes with Bruce profiles form a uniform electric field; ultraviolet light is generated by a vacuum ultraviolet light source (UV) embedded in the vacuum chamber, which irradiates the coated glass surface embedded in the center of the photocathode, exciting the initial electrons. A high DC voltage is applied between flat copper electrodes, and the initial electrons are accelerated in the DC electric field. The accelerated electrons interact with gas molecules. Various collision reactions occur between the gas molecules, among which ionization and adsorption reactions affect the number of electrons, and the number of electrons affects the magnitude of the current in the gas. By measuring the discharge current of the external circuit, the ionization and adsorption coefficients of the gas discharge are obtained by inversion.

[0043] Furthermore, the module for determining the effective ionization coefficient and critical breakdown field strength includes: The ionization coefficient and adsorption coefficient acquisition submodule is used to set the gas pressure. p 1 and spacing d Under certain conditions, change the applied electric field strength E To obtain different reduced field strengths E r ionization coefficient at the bottom α and adsorption coefficient η ; The effective ionization coefficient acquisition submodule is used to obtain the effective ionization coefficient based on the ionization coefficient. α and adsorption coefficient η Obtain the effective ionization coefficient of the corresponding insulating gas = α - η ; The current-spacing relationship determination submodule is used to generate the initial photoelectron current in the Townsend discharge experiment by continuously irradiating the photocathode with ultraviolet light. I 0. Under a uniform electric field, neglecting the secondary process, the discharge current in the circuit is 0. I Spacing d The relationship is: (1) The critical breakdown field strength determination submodule is used to set the air pressure as follows: p 1. Change the spacing d Measure different d Discharge current in the lower experimental circuit I Substituting into equation (1), we obtain different E r Below α and η ,when When = 0, it satisfies α = η The reduced field strength is denoted as E rc , E rc This represents the critical breakdown field strength of the insulating gas.

[0044] Furthermore, the power frequency insulation strength determination module includes: The relationship determination submodule is used to determine the effective ionization coefficient of insulating gases. With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; (2) The power frequency discharge voltage acquisition submodule is used to convert equation (2) to obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: (3) In the formula, E c For the power frequency breakdown field strength, in equation (2), =0 results in: (4) Substituting equation (4) into equation (3), we get: (5) For electronegative gases, the expression for the streamer discharge criterion is: (6) In the formula, x c The critical electron avalanche length at the start of the streamer. F It is an empirical constant; in a uniform electric field, x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: (7) Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: (8) In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: (9) In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

[0045] Furthermore, the insulating gas screening module includes: a method for detecting the critical breakdown field strength of the insulating gas. E rc and power frequency insulation strength U bUsing the liquefaction temperature and environmental performance indicators of candidate insulating gases as core screening indicators, insulating gases that meet the preset performance indicators are selected.

[0046] This invention provides a method and system for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters. Based on Townshend discharge theory, it uses the steady-state Townshend method or pulsed Townshend method to accurately measure the ionization coefficient and adsorption coefficient of candidate gases, and calculates their critical breakdown field strength, thereby establishing a quantitative screening system from microscopic electronic behavior to macroscopic insulation performance. The Townshend discharge experimental method is used to obtain the discharge characteristic parameters of environmentally friendly insulating gases at the mesoscopic level, and then the characterization coefficients related to the power frequency insulation strength are derived. Substituting these coefficients into the numerical simulation calculation expression of the power frequency discharge voltage of the environmentally friendly insulating gas, the normalized insulation strength of the environmentally friendly insulating gas under different gap distances, gas pressures, and mixing ratios can be obtained. This invention overcomes the shortcomings of traditional methods, such as low efficiency or unclear physical mechanisms. It reduces the number of power frequency discharge experiments and obtains the mesoscopic discharge characteristic parameters for specific environmentally friendly mixed gases, allowing for the determination of their insulation strength characterizing their physical nature in equipment on a unified basis.

[0047] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0048] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0049] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0050] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for screening environmentally friendly insulating gases for electrical equipment based on electron group parameters, characterized in that, include: Construct a candidate database of environmentally friendly insulating gases; Based on Townsend discharge theory, a Townsend discharge experimental system was constructed. Based on the Townsend discharge experimental system, Townsend discharge experiments are conducted for each insulating gas in the candidate database. Under the conditions of set gas pressure and spacing, the applied electric field strength is changed to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained. The power frequency insulation strength of the insulating gas is obtained based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure. Based on the critical breakdown field strength and power frequency insulation strength of the insulating gas, insulating gases that meet the preset performance indicators are selected from the candidate database.

2. The method according to claim 1, characterized in that, A candidate database of environmentally friendly insulating gases includes: Perfluoroisobutyronitrile (C4F7N), perfluoropentanone (C5F) 10 O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases (HFO1234ze), insulating gases, and binary or ternary mixtures of gases with CO2, N2, and O2 natural gases.

3. The method according to claim 1, characterized in that, The Townsend discharge experimental system is as follows: Two flat copper electrodes with Bruce profiles form a uniform electric field; ultraviolet light is generated by a vacuum ultraviolet light source (UV) embedded in the vacuum chamber, which irradiates the coated glass surface embedded in the center of the photocathode, exciting the initial electrons. A high DC voltage is applied between flat copper electrodes, and the initial electrons are accelerated in the DC electric field. The accelerated electrons interact with gas molecules. Various collision reactions occur between the gas molecules, among which ionization and adsorption reactions affect the number of electrons, and the number of electrons affects the magnitude of the current in the gas. By measuring the discharge current of the external circuit, the ionization and adsorption coefficients of the gas discharge are obtained by inversion.

4. The method according to claim 1, characterized in that, The Townsend discharge experiment, under set gas pressure and spacing conditions, varied the applied electric field strength to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas were obtained, including: Set air pressure p 1 and spacing d Under certain conditions, change the applied electric field strength E To obtain different reduced field strengths E r ionization coefficient at the bottom α and adsorption coefficient η ; Based on the ionization coefficient α and adsorption coefficient η Obtain the effective ionization coefficient of the corresponding insulating gas = α - η ; In the Townsend discharge experiment, an initial photoelectron current is generated by continuously irradiating the photocathode with ultraviolet light. I 0. Under a uniform electric field, neglecting the secondary process, the discharge current in the circuit is 0. I Spacing d The relationship is: （1） Let the air pressure be p 1. Change the spacing d Measure different d Discharge current in the lower experimental circuit I Substituting into equation (1), we obtain different E r Below α and η ,when When = 0, it satisfies α = η The reduced field strength is denoted as E rc , E rc This represents the critical breakdown field strength of the insulating gas.

5. The method according to claim 1, characterized in that, Based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure, the power frequency insulation strength of the insulating gas is obtained, including: Effective ionization coefficient of insulating gas With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; （2） Transforming equation (2), we obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: （3） In the formula, E c Let be the power frequency breakdown field strength. In equation (2), =0 results in: （4） Substituting equation (4) into equation (3), we get: （5） For electronegative gases, the expression for the streamer discharge criterion is: （6） In the formula, x c The critical electron avalanche length at the start of the streamer. F It is an empirical constant in a uniform electric field. x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: （7） Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: （8） In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: （9） In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

6. The method according to claim 1, characterized in that, Based on the critical insulation strength and power frequency insulation strength of the insulating gas, insulating gases that meet preset performance indicators are selected from the candidate database, including: The critical breakdown field strength of the insulating gas E rc and power frequency insulation strength U b Using the liquefaction temperature and environmental performance indicators of candidate insulating gases as core screening indicators, insulating gases that meet the preset performance indicators are selected.

7. A screening system for environmentally friendly insulating gases for electrical equipment based on electron group parameters, characterized in that, include: The candidate database construction module is used to build a candidate database of environmentally friendly insulating gases; The Townsend discharge experimental system construction module is used to construct a Townsend discharge experimental system based on the Townsend discharge theory. The module for determining the effective ionization coefficient and critical breakdown field strength is used to conduct Townsend discharge experiments for each insulating gas in the candidate database based on the Townsend discharge experimental system. The Townsend discharge experiment changes the applied electric field strength under set gas pressure and spacing conditions to obtain the ionization coefficient and adsorption coefficient under different reduced field strengths. Based on the ionization coefficient and adsorption coefficient, the effective ionization coefficient and critical breakdown field strength of the corresponding insulating gas are obtained. The power frequency insulation strength determination module is used to obtain the power frequency insulation strength of the insulating gas based on the relationship between the effective ionization coefficient of the insulating gas and the electric field and gas pressure. An insulating gas screening module is used to screen insulating gases that meet preset performance indicators from the candidate database based on the critical breakdown field strength and power frequency insulation strength of the insulating gas.

8. The system according to claim 7, characterized in that, A candidate database of environmentally friendly insulating gases includes: Perfluoroisobutyronitrile (C4F7N), perfluoropentanone (C5F) 10 O), trifluoromethanesulfonyl fluoride (CF3SO2F), fluorinated olefin gases (HFO1234ze), insulating gases, and binary or ternary mixtures of gases with CO2, N2, and O2 natural gases.

9. The system according to claim 7, characterized in that, The Townsend discharge experimental system is as follows: Two flat copper electrodes with Bruce profiles form a uniform electric field; ultraviolet light is generated by a vacuum ultraviolet light source (UV) embedded in the vacuum chamber, which irradiates the coated glass surface embedded in the center of the photocathode, exciting the initial electrons. A high DC voltage is applied between flat copper electrodes, and the initial electrons are accelerated in the DC electric field. The accelerated electrons interact with gas molecules. Various collision reactions occur between the gas molecules, among which ionization and adsorption reactions affect the number of electrons, and the number of electrons affects the magnitude of the current in the gas. By measuring the discharge current of the external circuit, the ionization and adsorption coefficients of the gas discharge are obtained by inversion.

10. The system according to claim 7, characterized in that, The module for determining the effective ionization coefficient and critical breakdown field strength includes: The ionization coefficient and adsorption coefficient acquisition submodule is used to set the gas pressure. p 1 and spacing d Under certain conditions, change the applied electric field strength E To obtain different reduced field strengths E r ionization coefficient at the bottom α and adsorption coefficient η ; The effective ionization coefficient acquisition submodule is used to obtain the effective ionization coefficient based on the ionization coefficient. α and adsorption coefficient η Obtain the effective ionization coefficient of the corresponding insulating gas = α - η ; The current-spacing relationship determination submodule is used to generate the initial photoelectron current in the Townsend discharge experiment by continuously irradiating the photocathode with ultraviolet light. I 0. Under a uniform electric field, neglecting the secondary process, the discharge current in the circuit is 0. I Spacing d The relationship is: （1） The critical breakdown field strength determination submodule is used to set the air pressure as follows: p 1. Change the spacing d Measure different d Discharge current in the lower experimental circuit I Substituting into equation (1), we obtain different E r Below α and η ,when When = 0, it satisfies α = η The reduced field strength is denoted as E rc , E rc This represents the critical breakdown field strength of the insulating gas.

11. The system according to claim 7, characterized in that, The power frequency insulation strength determination module includes: The relationship determination submodule is used to determine the effective ionization coefficient of insulating gases. With electric field E and air pressure p The relationship is expressed by equation (2), where A and B are constants related to the gas type; （2） The power frequency discharge voltage acquisition submodule is used to convert equation (2) to obtain the power frequency discharge voltage in a uniform electric field. U b The expression is: （3） In the formula, E c For the power frequency breakdown field strength, in equation (2), =0 results in: （4） Substituting equation (4) into equation (3), we get: （5） For electronegative gases, the expression for the streamer discharge criterion is: （6） In the formula, x c The critical electron avalanche length at the start of the streamer. F It is an empirical constant; in a uniform electric field, x c = d Since the effective ionization coefficients are equal, substituting them into equation (6) yields: （7） Simultaneously, the critical breakdown field strength for different physical quantities is transformed using ideal state equations, satisfying: （8） In the formula, k B Boltzmann constant, 1.38 * 10 -23 J / K; T is the gas temperature, in K; Substituting equations (7) and (8) into equation (5), the power frequency discharge voltage of the insulating gas is obtained as follows: （9） In the formula, p The pressure is the air pressure of the equipment, in MPa. d The distance between the equipment electrodes is related to the voltage level and is measured in mm; the power frequency discharge voltage is... U b The power frequency insulation strength of the insulating gas.

12. The system according to claim 7, characterized in that, An insulating gas screening module includes: a method for screening insulating gases based on their critical breakdown field strength. E rc and power frequency insulation strength U b Using the liquefaction temperature and environmental performance indicators of candidate insulating gases as core screening indicators, insulating gases that meet the preset performance indicators are selected.

13. A computer-readable storage medium, characterized in that, The storage medium stores a computer program for performing the method described in any one of claims 1 to 6.

14. An electronic device, characterized in that, The electronic device includes: processor; Memory used to store the processor's executable instructions; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 6.

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