Mixed environment-friendly gas proportioning method and system

Abstract

The invention discloses a mixed environment-friendly gas proportioning method and a mixed environment-friendly gas proportioning system, and relates to the technical field of environment-friendly insulating media, and the mixed environment-friendly gas proportioning method comprises the following steps: fitting by adopting a global optimization algorithm to obtain Antomillion characteristic constants of SF6, N2 and CO2 gases; calculating saturated vapor pressure under different gas components, and testing a curve of the breakdown voltage of the mixed gas along with the change of the applied voltage under different saturated vapor pressure and mixing proportions to obtain an optimal mixing proportion; and taking the environment-friendly gas obtained by mixing as an insulating medium and carrying out an arc extinguishing capability test. The environment-friendly gas is obtained by mixing 30% of SF6, 69% of N2 and 1% of CO2, and the gas is used as a gas insulation medium used in gas insulation equipment, so that the use amount of SF6 is reduced, the environment-friendly requirement is met, toxic decomposition products are reduced, the greenhouse effect is avoided, the insulating property and the arc extinguishing effect of the gas are ensured, and the service life of the gas is prolonged. And the stability and the safety can be ensured in different working environments.

Description

Technical Field

[0001] The invention relates to the technical field of environmentally friendly insulating media, and in particular to a mixed environmentally friendly gas proportioning method and system. Background Art

[0002] SF6 is an insulating and arc-extinguishing medium widely used in power systems. Due to its excellent insulation and arc-extinguishing performance, it is widely used in gas-insulated equipment. However, in recent years, new environmental protection policies have put forward new requirements for the power industry, and the greenhouse effect of SF6 has gradually attracted attention. Its global warming potential (GWP) is much higher than that of carbon dioxide, which has brought great pressure to environmental protection. In addition, SF6 gas is easy to liquefy in high-cold environments, which limits its application in extreme climates.

[0003] In order to reduce the use of SF6 and meet environmental protection requirements, the power industry has adopted a series of SF6 emission reduction measures. At the same time, since SF6 has been widely used in the power industry, researchers have been exploring gas insulation media. Commonly used gas insulation media include conventional gas or pure SF6 gas. However, the insulation level of conventional gas itself is not high, and excessive use of pure SF6 gas will cause serious greenhouse effect. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: how to improve the insulation level of SF6 while reducing the greenhouse effect.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a mixed environmentally friendly gas ratio method, comprising: using a global optimization algorithm to fit the Antoine characteristic constants of SF6, N2 and CO2 gases; calculating the saturated vapor pressure under different gas components, and testing the curve of the mixed gas breakdown voltage changing with the applied voltage under different saturated vapor pressures and mixing ratios to obtain the optimal mixing ratio; using the mixed environmentally friendly gas as an insulating medium and conducting an arc extinguishing ability test.

[0007] As a preferred scheme of the mixed environmentally friendly gas ratio method described in the present invention, the fitting of the Antoine characteristic constant is to obtain the Antoine characteristic constants of SF6, N2 and CO2 pure gases by fitting the data of pressure change of SF6, N2 and CO2 pure gases with temperature.

[0008] As a preferred embodiment of the mixed environmentally friendly gas ratio method of the present invention, the calculation of the saturated vapor pressure includes substituting the obtained Antoine characteristic constants of SF6, N2 and CO2 into the following formula:

[0009]

[0010] P1X1=PY1

[0011] P2X2=PY2

[0012] P3X3=PY3

[0013] P=P1Y1+P2Y2+P3Y3

[0014] X1+X2+X3=1

[0015] Y1+Y2+Y3=1

[0016] Wherein, P1, P2 and P3 are the saturated vapor pressures of component 1, component 2 and component 3 respectively; P is the saturated vapor pressure of the mixed gas; T is the temperature of the mixed gas; A1, B1, C1 are the Antoine characteristic constants of component 1; A2, B2, C2 are the Antoine characteristic constants of component 2; A3, B3, C3 are the Antoine characteristic constants of component 3; X1, X2, X3 are the mole fractions of component 1, component 2 and component 3 in the liquid phase; Y1, Y2, Y3 are the mole fractions of component 1, component 2 and component 3 in the gas phase; wherein component 1 is SF6 gas, component 2 is N2 gas, and component 3 is CO2 gas.

[0017] As a preferred embodiment of the mixed environmentally friendly gas ratio method of the present invention, the test of the variation of the breakdown voltage of the mixed gas with the applied voltage under different saturated vapor pressures and mixing ratios includes:

[0018] The discharge characteristics of the mixed gas under lightning impulse are tested using lightning impulse overvoltage. Before the experimental chamber is filled with SF6 and N2, it is first evacuated, and then filled with N2 for sufficient drying before evacuation. A double-headed gas filling port and a high-precision digital pressure gauge are installed under the experimental chamber, and a brass plate electrode with a spacing of 3mm is used as the experimental electrode. When the test chamber is configured with SF6 and N2, based on Dalton's law of partial pressure, a certain pressure of SF6 gas is first filled, and then a certain pressure of N2 is filled. It is left to stand for 24 hours to ensure uniform mixing. A Marx generator is used to generate lightning impulse voltage, and the 50% breakdown voltage U50% under lightning impulse is obtained by the step-up and step-down method. The voltage change value △U each time is 2% of the estimated U50%.

[0019] As a preferred embodiment of the mixed environmentally friendly gas proportioning method described in the present invention, the step-up and step-down method includes determining the initial lightning impulse voltage, applying the lightning impulse voltage, applying the lightning impulse voltage again after standing still, repeating the steps of applying and applying the lightning impulse voltage after standing still until the number of experiments reaches 30 effective experiments for each group of experiments, at which time the 50% breakdown voltage is obtained.

[0020] As a preferred embodiment of the mixed environmentally friendly gas ratio method of the present invention, the determining of the initial lightning impulse voltage includes selecting an initial lightning impulse voltage value U according to the electric field conditions, gas pressure and ratio of the gas gap, so that it is close to the breakdown voltage of 50% of the gas gap, and then determining the increment of the lightning impulse voltage;

[0021] The applying of lightning impulse voltage comprises applying a peak value of U K The standard lightning impulse voltage can be read at any time and the impulse voltage waveform can be recorded.

[0022] The step of applying the lightning impulse voltage again after standing still includes determining the voltage value applied this time according to the result of the last experiment after standing still. If the gas gap has been broken down, the peak voltage applied this time is modified to U K –△U; if there is no breakdown, the peak voltage applied this time is modified to U K +△U;

[0023] The method of obtaining the 50% breakdown voltage includes the following steps: i The number of times the impulse voltage is applied is n i , and finally the 50% breakdown voltage of the gas gap is calculated.

[0024] As a preferred scheme of the mixed environmentally friendly gas proportioning method described in the present invention, wherein: a power frequency breakdown experiment is carried out after the arc extinguishing energy test, and a curve of the breakdown voltage of the mixed gas of SF6, N2 and CO2 in different mixing ratios as the filling pressure changes is tested, and it is compared with the breakdown voltage of pure SF6 gas and pure N2 gas.

[0025] In the second aspect, another object of the present invention is to provide a mixed environmentally friendly gas proportioning system, including: a data acquisition module, a calculation module and a data processing module; the data acquisition module is used to collect the required experimental data; the calculation module is used to fit the Antoine characteristic constants of SF6, N2 and CO2 gases, and calculate the saturated vapor pressure under different gas components; the data processing module is used to compare the calculated data when applied to different conditions, and determine the optimal mixing ratio of the mixed gas.

[0026] In a third aspect, a computer device includes a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the mixed environmental protection gas proportioning method as described above when executing the computer program.

[0027] In a fourth aspect, a computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the mixed environmentally friendly gas proportioning method as described above.

[0028] Beneficial effects of the present invention: The mixed environmentally friendly gas proportioning method and system provided by the present invention mixes 30% SF6, 69% N2 and 1% CO2 to obtain environmentally friendly gas, and uses this gas as the gas insulating medium used in gas-insulated equipment, thereby reducing the amount of SF6 used, thereby ensuring compliance with green environmental protection requirements, reducing toxic decomposition products and avoiding the generation of greenhouse effects, and ensuring the insulating properties and arc extinguishing effect of the gas, and ensuring stability and safety under different working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0030] Figure 1 An overall flow chart of a mixed environmentally friendly gas proportioning method provided by one embodiment of the present invention;

[0031] Figure 2 A saturated vapor pressure value curve of a mixed gas of SF6, N2 and CO2 at different SF6 mixing ratios in a mixed environmentally friendly gas ratio method provided by one embodiment of the present invention;

[0032] Figure 3 A curve showing the variation of 50% positive polarity lightning impulse breakdown voltage versus gas pressure of a mixed gas of SF6, N2 and CO2 at different SF6 mixing ratios in a mixed environmentally friendly gas ratio method provided by one embodiment of the present invention;

[0033] Figure 4 A curve showing the variation of 50% negative polarity lightning impulse breakdown voltage versus gas pressure of a mixed gas of SF6, N2 and CO2 at different SF6 mixing ratios in a mixed environmentally friendly gas ratio method provided by one embodiment of the present invention;

[0034] Figure 5 A curve of the power frequency breakdown voltage versus gas pressure of a mixed gas of SF6, N2 and CO2 at different SF6 mixing ratios and different CO2 mixing ratios in a mixed environmentally friendly gas ratio method provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] Example 1

[0038] Reference Figure 1-2 , as an embodiment of the present invention, provides a mixed environmentally friendly gas ratio method, comprising:

[0039] S1: The Antoine characteristic constants of SF6, N2 and CO2 gases are obtained by fitting using a global optimization algorithm;

[0040] Furthermore, according to the experimental data, the global optimization algorithm is used to fit the Antoine characteristic constants of SF6, N2 and CO2 gases. Specifically, the saturated vapor pressure characteristics of the mixed gas of SF6, N2 and CO2 are calculated by combining the Antoine equation with the basic law of gas-liquid equilibrium. Specifically, when calculating the Antonie characteristic constant, the data of the pressure change of pure SF6 gas with temperature are fitted, and the Antonie characteristic constants A1, B1, and C1 of pure SF6 gas are obtained to be 7.227, 883.316, and 272.906; the data of the pressure change of pure N2 gas with temperature are fitted, and the Antonie characteristic constants A2, B2, and C2 of pure N2 gas are obtained to be 6.866, 306.365, and 273.217; the data of the pressure change of pure CO2 gas with temperature are fitted, and the Antonie characteristic constants A3, B3, and C3 of pure CO2 gas are obtained to be 9.64, 1284.07, and 268.432.

[0041] S2: Calculate the saturated vapor pressure under different gas components, and test the curve of the mixed gas breakdown voltage changing with the applied voltage under different saturated vapor pressure and mixing ratio to obtain the optimal mixing ratio;

[0042] Furthermore, the obtained Antoine characteristic constants of SF6, N2 and CO2 gases are substituted into the following formula to calculate the saturated vapor pressure under different gas components: The calculation of the Antoine equation is as follows:

[0043]

[0044] P1X1=PY1

[0045] P2X2=PY2

[0046] P3X3=PY3

[0047] P=P1Y1+P2Y2+P3Y3

[0048] X1+X2+X3=1

[0049] Y1+Y2+Y3=1

[0050] Wherein, P1, P2 and P3 are the saturated vapor pressures of component 1, component 2 and component 3 respectively; P is the saturated vapor pressure of the mixed gas; T is the temperature of the mixed gas; A1, B1, C1 are the Antoine characteristic constants of component 1; A2, B2, C2 are the Antoine characteristic constants of component 2; A3, B3, C3 are the Antoine characteristic constants of component 3; X1, X2, X3 are the mole fractions of component 1, component 2 and component 3 in the liquid phase; Y1, Y2, Y3 are the mole fractions of component 1, component 2 and component 3 in the gas phase; wherein component 1 is SF6 gas, component 2 is N2 gas, and component 3 is CO2 gas.

[0051] like Figure 2 As shown, the curve is a curve of the saturated vapor pressure of SF6, N2 and CO2 mixed gas and SF6 pure gas with temperature at different SF6 mixing ratios. It can be seen from the figure that with the increase of temperature, the saturated vapor pressure of the mixed gas at the same mixing ratio also gradually increases. At the same time, as the SF6 mixing ratio increases, the saturated vapor pressure of the mixed gas at the same gas pressure will decrease. According to the curve, when the gas pressure is 0.1MPa, when the maximum operating temperature of the electrical equipment is -20℃, the mixed gas mixing ratio cannot exceed 30%, otherwise the mixed gas will liquefy; and when the mixed gas mixing ratio is 30%, when the working gas pressure is 0.15MPa, the liquefaction temperature of the mixed gas is -84.32℃, which can meet the working requirements of gas-insulated equipment with an operating temperature of 10℃ to 25℃. After determining the curve, the mixing ratio and inflation pressure range of the mixed gas are determined according to the curve.

[0052] In practical applications, in addition to the saturated vapor pressure, the comprehensive insulation performance of the SF6, N2 and CO2 mixed gas must be investigated and compared with pure SF6 gas. Therefore, after testing the saturated vapor pressure of the SF6, N2 and CO2 mixed gas, it is also necessary to carry out power frequency breakdown, lightning impulse or partial discharge decomposition experiments to test and analyze the comprehensive insulation performance of the SF6, N2 and CO2 mixed gas, determine the difference in insulation performance between the SF6, N2 and CO2 mixed gas and pure SF6 gas, and determine the appropriate inflation pressure and the ratio of each gas component in the mixed gas.

[0053] According to the gas pressure ratio of the mixed gas and the mixing ratio of each component, the curves of the breakdown voltage of the mixed gas and the change with the applied voltage under different gas pressures and mixing ratios are tested. After testing, the optimal mixing ratio is 30% SF6, 69% N2, and 1% CO2. In addition, the arc extinguishing ability of the mixed gas must be tested. Specifically, the discharge characteristics of the mixed gas under lightning impulse are tested using lightning impulse overvoltage, and the negative polarity lightning impulse discharge characteristics of the mixed gas of SF6, N2 and CO2 under extremely non-uniform electric fields are studied. The specific preparation work includes: before the experimental cavity is filled with SF6 and N2, it is first vacuumed, and then filled with N2 for sufficient drying and then vacuumed. A double-headed gas filling port and a high-precision digital pressure gauge are installed under the experimental cavity, and a brass plate electrode with a spacing of 3mm is used as the experimental electrode. When the test cavity is configured with SF6 and N2, based on Dalton's law of partial pressure, a certain pressure of SF6 gas is first filled, and then a certain pressure of N2 is filled, and it is left to stand for 24 hours to ensure uniform mixing. A Marx generator is used to generate lightning impulse voltage, and the 50% breakdown voltage U50% under lightning impulse is obtained by the rise and fall method. Each voltage change value △U is 2% of the estimated U50%. During the test, if the voltage Ui is applied for the nth time and there is no breakdown, the voltage head Ui+△U is applied for the n+1th time; if there is a breakdown, the voltage applied for the n+1th time is Ui-△U. The number of effective tests for each group of tests is 30 to ensure the accuracy of U50%.

[0054] As one embodiment, the step-down / boost test is performed according to the following steps:

[0055] Step S2021: Determine the initial lightning impulse voltage. According to the electric field conditions, gas pressure and ratio of the gas gap, select an initial lightning impulse voltage value U so that it is close to the breakdown voltage of 50% of the gas gap. Then, determine the increment of lightning impulse voltage △U, which ranges from (0.5 to 1.0)σU K , σ is usually taken as 0.03.

[0056] Step S2022: Applying lightning impulse voltage. Applying a peak value of U KThe standard lightning impulse voltage is measured and the impulse voltage waveform is read at any time to record the experimental results. In order to ensure that this experiment is not affected by the previous experiment, it needs to be left still for more than 3 minutes to eliminate the free state.

[0057] Step S2023: After standing still, apply the lightning impulse voltage again. Determine the voltage value applied this time based on the result of the previous experiment. If the gas gap has been broken down, the peak voltage applied this time is modified to U K –△U; if there is no breakdown, the peak voltage applied this time is modified to U K +△U.

[0058] Step S2024: Repeat the operations from S2022 to S2023 until the number of experiments reaches 30 valid experiments for each group of experiments to ensure the accuracy of U50%.

[0059] Step S2025: Calculate the 50% breakdown voltage. i The number of times the impulse voltage is applied is n i , and finally the 50% breakdown voltage of the gas gap is calculated.

[0060] S3: Use the mixed environmentally friendly gas as an insulating medium and perform an arc extinguishing ability test.

[0061] Furthermore, a power frequency breakdown experiment is carried out to test the curve of the breakdown voltage of mixed gases of SF6, N2 and CO2 with different mixing ratios as a function of the filling pressure, and compare it with the breakdown voltage of pure SF6 gas and pure N2 gas.

[0062] Example 2

[0063] In one embodiment of the present invention, a mixed environmentally friendly gas proportioning system is provided, comprising:

[0064] Data acquisition module, calculation module and data processing module;

[0065] The data acquisition module is used to collect the required experimental data;

[0066] The calculation module is used to fit the Antoine characteristic constants of SF6, N2 and CO2 gases and calculate the saturated vapor pressure under different gas components;

[0067] The data processing module is used to compare the calculated data when applied to different conditions to determine the optimal mixing ratio of the mixed gas.

[0068] Example 3

[0069] An embodiment of the present invention is different from the first two embodiments in that:

[0070] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0071] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0072] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0073] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0074] Example 4

[0075] See also Figure 3 to Figure 5 , which is an embodiment of the present invention, provides a mixed environmentally friendly gas ratio method. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0076] like Figure 2 and Figure 3 As shown in the figure, it can be seen from the experimental data that the positive and negative polarity U50% of the mixed gas under different SF6 mixing ratios increases approximately linearly with the increase of the filling pressure, and the larger the mixing ratio, the faster the growth trend. At the same time, it can be found that at a lower mixing ratio, a high insulation strength close to that of SF6 can be achieved. Under the positive polarity impulse voltage, the U50% of the SF6, N2 and CO2 mixed gas with a 30% SF6 mixing ratio at a pressure of 0.18MPa is approximately equal to the U50% of the SF6 pure gas at a pressure of 0.1MPa; under the negative polarity impulse voltage, when the filling pressure is between 0.1MPa and 0.2MPa, the U50% of the SF6, N2 and CO2 mixed gas with a 30% SF6 mixing ratio is approximately equal to the U50% of the SF6 pure gas at the same pressure, showing good arc extinguishing insulation performance.

[0077] In actual operation, electrical equipment using SF6 / N2 as the insulating gas medium mainly has a slightly non-uniform electric field, with a non-uniformity coefficient between 1 and 2. Figure 4As shown, it can be concluded from the experimental data that with the increase of the filling voltage, the breakdown voltage value of the SF6, N2 and CO2 mixed gas increases linearly. Comparing the 30% SF6 mixed gas curve with the SF6 pure gas curve and the N2 pure gas curve, it can be found that the breakdown voltage of the 30% SF6, N2 and CO2 mixed gas at a pressure of 0.15MPa is approximately the same as the breakdown voltage of the SF6 pure gas at a pressure of 0.1MPa, and is much greater than the breakdown voltage of the N2 pure gas at the same pressure. After adding 1% CO2, it can be found that the breakdown voltage of the mixed gas at different pressures increases by 2.41kV to 6.82kV, and the breakdown voltage is significantly improved. By studying the saturated vapor pressure and comprehensive insulation properties of the SF6, N2 and CO2 mixed gas, it can be found that the SF6, N2 and CO2 mixed gas with a mixing ratio of 30%, a N2 mixing ratio of 29%, and a CO2 mixing ratio of 1% has passed the comprehensive evaluation and meets the use conditions in both performances.

[0078] 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 preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A mixed environmentally friendly gas ratio method, characterized in that: include: The Antoine characteristic constants of SF6, N2 and CO2 gases were fitted using a global optimization algorithm. Calculate the saturated vapor pressure under different gas components, and test the curve of the mixed gas breakdown voltage changing with the applied voltage under different saturated vapor pressure and mixing ratio to obtain the optimal mixing ratio; The mixed environmentally friendly gas is used as an insulating medium and the arc extinguishing ability is tested.

2. The mixed environmentally friendly gas ratio method according to claim 1, characterized in that: The fitting of the Antoine characteristic constant is to obtain the Antoine characteristic constants of the pure gases SF6, N2 and CO2 by fitting the data of the pressure variation of the pure gases SF6, N2 and CO2 with the temperature.

3. The mixed environmentally friendly gas ratio method according to claim 2, characterized in that: The calculation of the saturated vapor pressure includes substituting the obtained Antoine characteristic constants of SF6, N2 and CO2 into the following formula: P1X1=PY1 P2X2=PY2 P3X3=PY3 P=P1Y1+P2Y2+P3Y3 X1+X2+X3=1 Y1+Y2+Y3=1 Wherein, P1, P2 and P3 are the saturated vapor pressures of component 1, component 2 and component 3 respectively; P is the saturated vapor pressure of the mixed gas; T is the temperature of the mixed gas; A1, B1, C1 are the Antoine characteristic constants of component 1; A2, B2, C2 are the Antoine characteristic constants of component 2; A3, B3, C3 are the Antoine characteristic constants of component 3; X1, X2, X3 are the mole fractions of component 1, component 2 and component 3 in the liquid phase; Y1, Y2, Y3 are the mole fractions of component 1, component 2 and component 3 in the gas phase; wherein component 1 is SF6 gas, component 2 is N2 gas, and component 3 is CO2 gas.

4. The mixed environmentally friendly gas ratio method according to claim 3, characterized in that: The test of the variation of the breakdown voltage of the mixed gas with the applied voltage under different saturated vapor pressures and mixing ratios includes: The discharge characteristics of the mixed gas under lightning impulse are tested using lightning impulse overvoltage. Before the experimental chamber is filled with SF6 and N2, it is first evacuated, and then filled with N2 for sufficient drying before evacuation. A double-headed gas filling port and a high-precision digital pressure gauge are installed under the experimental chamber, and a brass plate electrode with a spacing of 3mm is used as the experimental electrode. When the test chamber is configured with SF6 and N2, based on Dalton's law of partial pressure, a certain pressure of SF6 gas is first filled, and then a certain pressure of N2 is filled. It is left to stand for 24 hours to ensure uniform mixing. A Marx generator is used to generate lightning impulse voltage, and the 50% breakdown voltage U50% under lightning impulse is obtained by the step-up and step-down method. The voltage change value △U each time is 2% of the estimated U50%.

5. The mixed environmentally friendly gas ratio method according to claim 4, characterized in that: The step-up / down voltage method includes determining an initial lightning impulse voltage, applying the lightning impulse voltage, applying the lightning impulse voltage again after standing still, repeating the steps of applying and applying the lightning impulse voltage after standing still until the number of experiments reaches 30 effective experiments per group of experiments, at which time a 50% breakdown voltage is obtained.

6. The mixed environmentally friendly gas ratio method according to claim 5, characterized in that: Determining the initial lightning impulse voltage includes selecting an initial lightning impulse voltage value U according to the electric field conditions, gas pressure and ratio of the gas gap, so that it is close to 50% of the breakdown voltage of the gas gap, and then determining the increment of the lightning impulse voltage; The applying of lightning impulse voltage comprises applying a peak value of U K The standard lightning impulse voltage can be read at any time and the impulse voltage waveform can be recorded. The step of applying the lightning impulse voltage again after standing still includes determining the voltage value applied this time according to the result of the last experiment after standing still. If the gas gap has been broken down, the peak voltage applied this time is modified to U K –△U; if there is no breakdown, the peak voltage applied this time is modified to U K +△U; The method of obtaining the 50% breakdown voltage includes the following steps: i The number of times the impulse voltage is applied is n i , and finally the 50% breakdown voltage of the gas gap is calculated.

7. The mixed environmentally friendly gas ratio method according to claim 6, characterized in that: After the arc extinguishing energy test, a power frequency breakdown experiment is carried out to test the curve of the breakdown voltage of the mixed gas of SF6, N2 and CO2 with different mixing ratios as the filling pressure changes, and compare it with the breakdown voltage of pure SF6 gas and pure N2 gas.

8. A system using the mixed environmentally friendly gas proportioning method according to any one of claims 1 to 7, characterized in that: include: Data acquisition module, calculation module and data processing module; The data acquisition module is used to collect required experimental data; The calculation module is used to fit the Antoine characteristic constants of SF6, N2 and CO2 gases and calculate the saturated vapor pressure under different gas components; The data processing module is used to compare the calculated data when applied to different conditions to determine the optimal mixing ratio of the mixed gas.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the mixed environmentally friendly gas proportioning method described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the mixed environmentally friendly gas proportioning method described in any one of claims 1 to 7 are implemented.

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