CN117538708A - Calculation method of dielectric strength of binary environment-friendly mixed gas - Google Patents
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- 238000004364 calculation method Methods 0.000 title claims description 32
- 238000000034 method Methods 0.000 claims abstract description 50
- 230000002195 synergetic effect Effects 0.000 claims abstract description 44
- 238000012512 characterization method Methods 0.000 claims abstract description 37
- 238000012360 testing method Methods 0.000 claims abstract description 31
- 239000007789 gas Substances 0.000 claims description 289
- XOFYZVNMUHMLCC-ZPOLXVRWSA-N prednisone Chemical compound O=C1C=C[C@]2(C)[C@H]3C(=O)C[C@](C)([C@@](CC4)(O)C(=O)CO)[C@@H]4[C@@H]3CCC2=C1 XOFYZVNMUHMLCC-ZPOLXVRWSA-N 0.000 claims description 12
- 238000005421 electrostatic potential Methods 0.000 claims description 11
- 238000005457 optimization Methods 0.000 claims description 7
- 230000015556 catabolic process Effects 0.000 claims description 6
- 238000004057 DFT-B3LYP calculation Methods 0.000 claims description 5
- 238000012937 correction Methods 0.000 claims description 4
- 230000010287 polarization Effects 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- MOYKHGMNXAOIAT-JGWLITMVSA-N isosorbide dinitrate Chemical compound [O-][N+](=O)O[C@H]1CO[C@@H]2[C@H](O[N+](=O)[O-])CO[C@@H]21 MOYKHGMNXAOIAT-JGWLITMVSA-N 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 238000012795 verification Methods 0.000 claims description 3
- 238000011160 research Methods 0.000 abstract description 16
- 229910018503 SF6 Inorganic materials 0.000 abstract description 7
- 230000009878 intermolecular interaction Effects 0.000 abstract description 3
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 abstract description 3
- 229960000909 sulfur hexafluoride Drugs 0.000 abstract description 3
- 238000012216 screening Methods 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000003775 Density Functional Theory Methods 0.000 description 1
- 238000013528 artificial neural network Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000002884 conformational search Methods 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
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- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- 239000005431 greenhouse gas Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1281—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of liquids or gases
Abstract
The invention provides a method for calculating dielectric strength of binary environment-friendly mixed gas, which simultaneously considers intermolecular interaction on the premise of obtaining single-molecule characteristic parameters and provides a characterization method of synergistic effect of binary environment-friendly mixed gas and relative SF (sulfur hexafluoride) thereof 6 The method for calculating the dielectric strength solves the problems that in the prior art, only the dielectric strength of single gas can be predicted or the dielectric strength of the existing mixed gas can be obtained only by adopting a test research method, but the dielectric strength of unknown binary mixed gas or newly configured binary mixed gas which is not subjected to test research can not be predicted.
Description
Technical Field
The invention relates to the field of gas insulating media of electrical equipment, in particular to a method for calculating dielectric strength of binary environment-friendly mixed gas.
Background
SF 6 The insulating material has good insulating and arc extinguishing characteristics, and can be widely applied to gas insulating electrical equipment in the links of power system transmission, transformation, distribution and the like. Including Gas Insulated Switchgear (GIS), transmission lines (GIL), transformers (GIT), and cabinet closed switchgear (C-GIS), etc. But SF 6 Is currently known as the strongest greenhouse gas with global warming potential GWP of CO 2 24600 times of (2). In addition, SF 6 The life in the atmosphere is as long as 3200 years, and natural carbon circulation such as photosynthesis of vegetation is not participated, and the influence is generated compared with direct emission of equivalent CO 2 And more long. Therefore, in order to achieve the goals of carbon peak reaching and carbon neutralization, the novel environment-friendly insulating gas is accelerated to be screened or designed to gradually replace SF 6 Has become a key task for green low carbonization of propulsion power equipment.
SF 6 The research methods of the alternative gas can be classified into two major categories, namely test screening and theoretical calculation method screening. The dielectric strength of the existing single gas or mixed gas can only be obtained through the test, but the dielectric strength of a new gas or the dielectric strength of the new gas after the new gas is mixed with the buffer gas cannot be predicted, so that the development of the new environment-friendly insulating gas is slow. Heretofore, SF can not be screened or synthesized in an electric power system 6 A single gas is realized that is completely replaced, so that the mixed gas becomes the currently best temporary proposal. However, if the mixed gas is screened by the traditional test method, the workload is large and the efficiency is low. The theoretical calculation method can be used for researching the dielectric strength of the mixed gas in a more essential level, breaks through space-time limitation and improves research efficiency.
The inventor found in the research process of the present application that in the prior art, for a single gas, a structure-activity relation model capable of approximately estimating the dielectric strength of the single gas has been constructed, for example, a screening method of a high-insulation strength gas disclosed in the chinese invention patent application with publication No. CN112147473a, a gas dielectric strength prediction method based on neural network disclosed in the chinese invention patent application with publication No. CN112162182a, and a solution molecular cross section based on density functional theory disclosed in the chinese invention patent application with publication No. CN112182865A to find a substitute SF 6 SF based on molecular structure parameter disclosed in Chinese patent publication No. CN112634998B 6 Alternative gas search methods. However, for mixed gas, because of the synergistic effect, the dielectric strength of the mixed gas cannot be obtained by directly calculating the weight of the component gas, so that no calculation method for quickly obtaining the dielectric strength of the mixed gas is available at present.
Disclosure of Invention
The invention provides a calculation method of dielectric strength of binary environment-friendly mixed gas, which aims to solve the problems that in the prior art, only the dielectric strength of single gas can be predicted or only the dielectric strength of the existing mixed gas can be obtained by adopting a test research method, but the dielectric strength of unknown binary mixed gas or newly configured binary mixed gas which is not subjected to test research can not be predicted.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a calculating method of dielectric strength of binary environment-friendly mixed gas comprises the following steps:
s1, acquiring a single-molecule stable structure and single-molecule characteristic parameters of each component gas molecule in binary environment-friendly mixed gas to be detected;
s2, substituting single molecular characteristic parameters of each component gas into the constructed single gas relative SF 6 A dielectric strength calculation model of the gas to obtain the relative SF of the single-component gas 6 Dielectric strength of the gas; or obtaining the relative SF of the existing single-component gas by breakdown test 6 Dielectric strength of the gas;
s3, randomly generating a plurality of initial bimolecular cluster configurations formed by single-molecule stable structures of component gas, performing structural optimization on the initial bimolecular cluster configurations to obtain stable bimolecular configurations, and calculating to obtain Boltzmann distribution of the stable bimolecular configurations;
s4, taking the Boltzmann distribution proportion of the stable bimolecular configuration as a weight to obtain bimolecular characteristic parameters;
s5, substituting the bimolecular characteristic parameters into the constructed synergistic effect characterization coefficient prediction model to obtain a synergistic effect characterization coefficient of the mixed gas;
s6, relative SF from single component gas 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 Dielectric strength of the gas; binary environment-friendly mixed gas relative SF under high proportion section 6 The dielectric strength of the gas is obtained by linear fitting, so as to obtain the binary environment-friendly mixed gas relative SF in the range of 0-100 percent of the duty ratio 6 Is used for the dielectric strength of the steel sheet.
Further, the single gas dielectric strength calculation model in step S2 is:
E r-SF6 ＝0.41A s+ 2 +0.176f(E L )+0.445f(αχ)+0.028f(V s,max )-0.076
wherein E is r-SF6 Indicating the relative SF of the single gas 6 Dielectric strength of the gas; a is that s+ Representing the positive electrostatic potential surface area of such a single gas molecule; e (E) L Representing the lowest unoccupied orbital energy of such a single gas molecule; alpha represents the polarization rate; χ represents absolute electronegativity; v (V) s,max Representing the maximum value of the surface electrostatic potential of the single gas molecule;
wherein f (E) L )＝0.735E L -0.756 ，f(αχ)＝0.001(αχ) 2 +0.017αχ+0.089，f(V s,max )＝|-0.031V s,max 2 +1.032V s,max -0.011|。
Further, the step S3 specifically includes the following steps:
s31, adopting a cluster configuration search program, namely generating a plurality of initial double-molecule cluster configurations consisting of single-molecule stable structures of component gases by adopting a genmer in Molclus respectively at random;
s32, performing structural optimization and frequency verification calculation on the initial configuration of the bimolecular cluster by adopting a B3LYP/6-311G method to obtain a stable bimolecular configuration without virtual frequency;
s33, after the stable bimolecular configuration without the virtual frequency is obtained, removing the stable bimolecular configuration with similar energy and too high geometric structure similarity by using an isostat tool in Molclus, and setting the default value in the using program by parameters, namely, the energy threshold value for distinguishing clusters is 0.5kcal/mol, and the geometric threshold value for distinguishing clusters is
S34, calculating energy for stabilizing the bimolecular configuration by adopting a M06-2X/6-311+G method;
s35, constructing a Boltzmann distribution proportion calculation method for obtaining a stable bimolecular configuration:
wherein i, j is the number of stable bimolecular configuration, n i And n j Respectively represent the i < th > and j < th > stable bimolecular configurations, B i Is the proportion of the ith stable bimolecular configuration, E is the energy of the stable bimolecular configuration, and delta E i And delta E j The energy of the i and j stable bimolecular configurations and the energy minimum E in all stable bimolecular configurations are respectively min T is the temperature and R is the ideal gas constant.
Further, in step S4, the boltzmann distribution ratio of each stable bimolecular configuration obtained in step S3 is taken as a weight to calculate and obtain bimolecular characteristic parameters of the stable bimolecular configuration; the bimolecular characteristic parameter of the stable bimolecular configuration includes average binding energy delta E int-w Negative deviation of electrostatic potential, balance vAnd volume V, wherein the binding energy ΔE int During calculation, an equalization correction method is adopted to eliminate the overlapping error of the base group, delta E int-w For the weighted binding energy, n is the number of atoms in the bimolecular configuration.
Further, the synergistic effect characterization coefficient prediction model in step S5 is:
wherein N is a synergistic effect characterization coefficient.
Further, the SF is relative to the SF by a single component gas 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 The method for dielectric strength of the gas comprises the following steps:
the single gas obtained in the step S2 is processed with respect to SF 6 The dielectric strength of the (C) and the synergistic effect characterization coefficient N value obtained in S5 are substituted into the following formula to obtain the low-proportion binary environment-friendly mixed gas relative SF 6 Dielectric strength of gas:
wherein E is Mr-L 、E mr 、E bfr The two-element environment-friendly mixed gas, the environment-friendly electric affinity gas pure gas and the buffer gas pure gas relative SF 6 Dielectric strength, E Mr-L Refers to the relative SF of binary environment-friendly mixed gas in a low proportion section 6 Dielectric strength of (a); k is the molar ratio of the environment-friendly electric affinity gas in the mixed gas, and N is the synergistic effect characterization coefficient.
Further, the low proportion section in the step S6 refers to the part of the environment-friendly electric affinity gas, wherein the molar ratio k of the environment-friendly electric affinity gas in the mixed gas is more than 0 and less than or equal to 20 percent; the high proportion section refers to the part of the environment-friendly electric affinity gas with the molar ratio k of 20 < k < 100% in the mixed gas.
Further, in the step S6, the binary environment-friendly mixed gas is compared with SF under the high proportion section 6 The use of linear fitting for dielectric strength of gas refers to the use of a binary environment-friendly mixed gas obtained in step S6 when the environment-friendly electric affinity gas is at a molar ratio of k=20% in the mixed gas to SF 6 The calculation result of the dielectric strength of the gas and the environmental friendly electric affinity gas single component gas relative SF obtained in the step S2 6 Is a linear fit of the dielectric strength of (c).
By adopting the technical scheme, the invention has the following beneficial effects:
the invention provides a method for calculating dielectric strength of binary environment-friendly mixed gas, which simultaneously considers intermolecular interaction on the premise of obtaining single molecule characteristic parameters, and provides a characterization method for synergistic effect of binary environment-friendly mixed gas and relative SF (sulfur hexafluoride) thereof 6 The method for calculating the dielectric strength solves the problems that in the prior art, only the dielectric strength of single gas can be predicted or the dielectric strength of the existing mixed gas can be obtained only by adopting a test research method, but the dielectric strength of unknown binary mixed gas or newly configured binary mixed gas which is not subjected to test research can not be predicted, and is environment-friendly mixed gasThe gas design, buffer gas screening and mixing proportion are preferably provided for basis and support, so that the research on the environment-friendly mixed gas scheme is carried out more efficiently and more pertinently, the research efficiency of environment-friendly insulating gas is improved, the research risk and cost are reduced, and manpower and material resources are saved.
Drawings
FIG. 1 is a flow chart of a method for calculating dielectric strength of a binary environment-friendly mixed gas according to a preferred embodiment of the invention;
FIG. 2 shows a single gas relative SF provided by an embodiment of the present invention 6 Comparing the predicted value of the dielectric strength calculation model with the test value;
FIG. 3 is a graph showing a model of a prediction of a synergistic effect characterization coefficient according to an embodiment of the present invention 4 F 7 Comparing the predicted value of the N mixed gas with the test value;
fig. 4 is a comparison between a calculated value and a test value of a method for calculating dielectric strength of a binary environment-friendly mixed gas according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, a method for calculating dielectric strength of a binary environment-friendly mixed gas according to a preferred embodiment of the present invention includes the following steps:
s1, acquiring a single-molecule stable structure and single-molecule characteristic parameters of each component gas molecule in the binary environment-friendly mixed gas to be detected.
Optionally, the environment-friendly binary mixed gas in the embodiment is environment-friendly electric affinity gas C 4 F 7 N are respectively with buffer gas He, ne, ar, N 2 、CO 2 、CF 4 、C 2 F 6 、C 3 F 6 、C 3 F 8 Combining the obtained mixed gas to obtain C 4 F 7 N/He、C 4 F 7 N/Ne、C 4 F 7 N/Ar、C 4 F 7 N/N 2 、C 4 F 7 N/CO 2 、C 4 F 7 N/CF 4 、C 4 F 7 N/C 2 F 6 、C 4 F 7 N/C 3 F 6 And C 4 F 7 N/C 3 F 8 9 kinds of mixed gases are provided.
Wherein C in the present embodiment 4 F 7 N、He、Ne、Ar、N 2 、CO 2 、CF 4 、C 2 F 6 、C 3 F 6 、C 3 F 8 The single molecule stable molecular structure of (2) is obtained by adopting a B3LYP/6-311G calculation method in quantum chemistry software. The method for acquiring the single molecule characteristic parameters comprises the following steps: in the Multiwfn program (Quantum chemistry wave function analysis program), the positive electrostatic potential surface area A is calculated by using the default lattice point precision of the program to the Van der Waals surface with the electron density of 0.001a.u s+ And a surface electrostatic potential maximum value V s,max The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the polarization rate alpha by adopting a B3LYP/6-311G calculation method in quantum chemistry software; the minimum unoccupied orbit energy E is obtained by adopting a calculation method of M06-2X/6-311+G in quantum chemistry software L And absolute electronegativity χ.
S2, substituting single molecular characteristic parameters of each component gas into the constructed single gas relative SF 6 A dielectric strength calculation model of the gas to obtain the relative SF of the single-component gas 6 Dielectric strength of the gas; or obtaining the existing single-component gas relative SF by a power frequency breakdown test or a withstand voltage test 6 Dielectric strength of gasDegree. Wherein, the "existing" gas refers to the known gas which is found in nature or synthesized artificially; by "nonexistent" gas is meant an unknown gas that is not currently found or synthesized.
In the present embodiment, the single gas in step S2 is relative to SF 6 The dielectric strength calculation model of the gas is as follows:
E r-SF6 ＝0.41A s+ 2 +0.176f(E L )+0.445f(αχ)+0.028f(V s,max )-0.076
wherein E is r-SF6 Indicating the relative SF of the single gas 6 Dielectric strength of the gas; a is that s+ Representing the positive electrostatic potential surface area of such a single gas molecule; e (E) L Representing the lowest unoccupied orbital energy of such a single gas molecule; alpha represents the polarization rate; χ represents absolute electronegativity; v (V) s,max Representing the maximum value of the surface electrostatic potential of the single gas molecule;
wherein f (E) L )＝0.735E L -0.756 ，f(αχ)＝0.001(αχ) 2 +0.017αχ+0.089，f(V s,max )＝|-0.031V s,max 2 +1.032V s,max -0.011|。
C is obtained by adopting a power frequency breakdown test or a withstand voltage test 4 F 7 N、He、Ne、Ar、N 2 、CO 2 、CF 4 、C 2 F 6 、C 3 F 6 And C 3 F 8 Relative SF 6 The dielectric strength of (c) is a method of the prior art and is not described in detail herein.
In this step, the SF is relative to the SF by a single gas 6 C calculated by dielectric strength calculation model of gas 4 F 7 N、He、Ne、Ar、N 2 、CO 2 、CF 4 、C 2 F 6 、C 3 F 6 And C 3 F 8 Relative SF 6 Predicted dielectric strength and SF for the above gas obtained by power frequency breakdown test 6 The dielectric strength test value is compared with the result of the test, referring to fig. 2.
S3, randomly generating a plurality of initial bimolecular cluster configurations formed by the single-molecule stable structures of the component gas, performing structural optimization on the initial bimolecular cluster configurations to obtain stable bimolecular configurations, and calculating to obtain Boltzmann distribution of the stable bimolecular configurations.
In this embodiment, the step S3 specifically includes the following steps:
s31, adopting a cluster configuration search program, and randomly generating a plurality of bimolecular cluster initial configurations formed by the single-molecule stable structures of the component gas by the genmers in Molclus. Preferably, in order to eliminate the influence of empirical determination, the cluster configuration search program molplus is adopted to randomly generate not less than 25 initial configurations of the environment-friendly electric affinity gas pure gas and buffer gas bimolecular clusters respectively, in this embodiment, 30C are randomly generated 4 F 7 N with buffer gas bimolecular cluster initial configuration comprising: c (C) 4 F 7 N…He、C 4 F 7 N…Ne、C 4 F 7 N…Ar、C 4 F 7 N…N 2 、C 4 F 7 N…CO 2 、C 4 F 7 N…CF 4 、C 4 F 7 N…C 2 F 6 、C 4 F 7 N…C 3 F 6 And C 4 F 7 N…C 3 F 8 . The mollus employed in this step is a procedure for cluster configuration search and molecular conformational search, with the genmer modules in mollus being used to quickly and easily generate the initial configuration required for mollus.
S32, adopting a B3LYP/6-311G method to perform structural optimization and frequency verification calculation on the initial configuration of the bimolecular cluster to obtain a stable bimolecular configuration without virtual frequency.
S33, after the stable bimolecular configuration without the virtual frequency is obtained, removing the stable bimolecular configuration with similar energy and too high geometric structure similarity by using an isostat tool in Molclus, and setting the default value in the using program by parameters, namely, the energy threshold value for distinguishing clusters is 0.5kcal/mol, and the geometric threshold value for distinguishing clusters is
S34, calculating the energy for stabilizing the bimolecular configuration by adopting a M06-2X/6-311+G method.
S35, constructing a Boltzmann distribution proportion calculation method for obtaining a stable bimolecular configuration:
wherein i, j is the number of stable bimolecular configuration, n i And n j Respectively represent the i < th > and j < th > stable bimolecular configurations, B i Is the proportion of the ith stable bimolecular configuration, E is the energy of the stable bimolecular configuration, and delta E i And delta E j The energy of the i and j stable bimolecular configurations and the energy minimum E in all stable bimolecular configurations are respectively min T is the temperature and R is the ideal gas constant.
And S4, taking the Boltzmann distribution proportion of the stable bimolecular configuration as a weight, and obtaining the bimolecular characteristic parameter.
In step S4 of the present embodiment, the boltzmann distribution ratio of each stable bimolecular configuration obtained in step S3 is used as a weight to calculate and obtain the bimolecular characteristic parameter of the stable bimolecular configuration; the bimolecular characteristic parameter of the stable bimolecular configuration includes average binding energy (delta E) int-w N), the degree of balance v, the negative deviation of the electrostatic potentialAnd volume V, wherein the binding energy ΔE int The base group overlapping error (basic-set superposition error, BSSE) and delta E are eliminated by adopting an equalization correction method (counterpoise correction, CP) during calculation int-w For the weighted binding energy, n is the number of atoms in the bimolecular configuration.
S5, substituting the bimolecular characteristic parameters into the constructed synergistic effect characterization coefficient prediction model to obtain the synergistic effect characterization coefficient of the mixed gas.
In this embodiment, the synergistic effect characterization coefficient prediction model in step S5 is:
N＝0.139×(ΔE int-w /n)-8.555ν+12.83σ- 2 +1.335V+1.704
wherein N is a synergistic effect characterization coefficient.
In the step, C is obtained by adopting a synergistic effect characterization coefficient prediction model 4 F 7 The comparison result of the predicted value and the test value of the N mixed gas synergistic effect characterization coefficient N is shown in fig. 3. Wherein C is 4 F 7 The test value of the N mixed gas synergistic effect characterization coefficient N is obtained by the following method:
wherein U is M 、U m 、U bf Respectively two environment-friendly mixed gases (C in the embodiment) 4 F 7 N mixed gas), environment-friendly electric affinity gas pure gas (C in this embodiment) 4 F 7 N pure gas) and buffer gas pure gas, U m >U bf The method comprises the steps of carrying out a first treatment on the surface of the k is an environmentally friendly, electrically compatible gas pure gas, e.g. C 4 F 7 Molar ratio of N in the mixed gas; n is the synergistic effect characterization coefficient. The relation between the synergistic effect characterization coefficient N and the mixed gas synergistic effect is as follows: when n=1, the mixed gas dielectric strength U M Is in linear relation with the mixing proportion k; when 0 is less than or equal to N<1, dielectric strength U of mixed gas M The N value is smaller, and the synergistic effect is more remarkable; when N is>1, dielectric strength U of mixed gas M The negative synergistic effect is shown with the mixing proportion k, and the larger the N value is, the more remarkable the negative synergistic effect is.
S6, relative SF from single component gas 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 Dielectric strength of the gas; binary environment-friendly mixed gas relative SF under high proportion section 6 The dielectric strength of the gas is obtained by linear fitting, so as to obtain the binary environment-friendly mixed gas relative SF in the range of 0-100 percent of the duty ratio 6 Is used for the dielectric strength of the steel sheet.
In the present embodiment, low in step S6The proportional band refers to an environmentally friendly, electrically compatible gas, e.g. C 4 F 7 The mixed gas with the ratio k of N in the mixed gas being more than 0 and less than or equal to 20 percent is formed by the single component gas relative to SF 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 The method for dielectric strength of the gas comprises the following steps:
relative SF of the single gas obtained in S2 6 Substituting the dielectric strength of the gas and the N value of the synergistic effect characterization coefficient obtained in S5 into the following formula to obtain the low-proportion-section binary environment-friendly mixed gas relative SF 6 Dielectric strength of gas:
wherein E is Mr-L 、E mr 、E bfr The two-element environment-friendly mixed gas, the environment-friendly electric affinity gas pure gas and the buffer gas pure gas relative SF 6 Dielectric strength, E Mr-L Refers to the relative SF of binary environment-friendly mixed gas in a low proportion section 6 Dielectric strength of (a); k is an environmentally friendly, electron affinity gas, e.g. C 4 F 7 The ratio of N in the mixed gas, N is the characterization coefficient of the synergistic effect.
In this embodiment, the high proportion section refers to an environmentally friendly electric affinity gas, such as C 4 F 7 N is mixed gas with molar ratio k of 20 < k < 100% in the mixed gas, and the binary environment-friendly mixed gas under the high proportion section in step S6 has relative SF 6 The use of linear fitting of the dielectric strength of the gas means that the gas is environmentally friendly and has an electrical affinity in step S6, e.g. C 4 F 7 Binary environment-friendly mixed gas relative SF obtained when N is the molar ratio k=20% of mixed gas 6 The result of calculation of the dielectric strength of the gas is correlated with the environmentally friendly electric affinity gas obtained in step S2, e.g. C 4 F 7 N single gas (k=100%) vs SF 6 Is a linear fit of the dielectric strength of (c).
I.e. according to the method of the invention C is obtained 4 F 7 N mixed gas as C 4 F 7 N is in a molar ratio of 0-100% relative to SF 6 Dielectric strength E of (2) Mr .9 kinds of C 4 F 7 N mixed gas relative SF 6 The comparison of the dielectric strength calculation value of (c) and the test value obtained by the power frequency breakdown test is shown in fig. 4. As can be seen from FIG. 4, in the low-proportion section, the synergistic effect characterization coefficient N of the mixed gas can better reflect C 4 F 7 Nonlinear characteristics of the N mixed gas relative dielectric strength test results; the high proportion section adopts linear fitting and accords with the variation trend of the test result. Comparison of 9 kinds of C 4 F 7 The size of the N mixed gas synergistic effect characterization coefficient N can obtain the synergistic effect strength as follows: c (C) 4 F 7 N/CO 2 >C 4 F 7 N/CF 4 >C 4 F 7 N/N 2 >C 4 F 7 N/C 3 F 6 >C 4 F 7 N/Ar>C 4 F 7 N/He>C 4 F 7 N/Ne>C 4 F 7 N/C 2 F 6 >C 4 F 7 N/C 3 F 8 ，C 4 F 7 N/CO 2 The synergistic effect of the mixed gas is strongest, and the mixed gas replaces SF 6 Has larger potential.
According to the single gas dielectric strength calculation model, the synergistic effect characterization coefficient N value prediction model and the synergistic effect characterization coefficient N calculation model disclosed by the application, the environment-friendly binary mixed gas can be obtained at any ratio of 0-100% of the ratio range relative to SF 6 The dielectric strength of the mixed gas can be predicted by detecting the proportion of component gases in the mixed gas, and the dielectric strength of the mixed gas can be obtained in real time, so that whether the dielectric strength of the gas insulation equipment touches a limit value or not can be timely prompted, and the operation safety of the equipment is improved.
Based on the same principle, the method for calculating the dielectric strength of the binary environment-friendly mixed gas disclosed by the embodiment of the invention is also suitable for CF 3 SO 2 F/He、CF 3 SO 2 F/Ne、CF 3 SO 2 F/Ar、CF 3 SO 2 F/CO 2 And CF (compact F) 3 SO 2 F/N 2 And (3) mixing the gases. The above 5 kinds of CF 3 SO 2 F mixture gas relative SF 6 Refer to table 1 for the dielectric strength predictions and test.
TABLE 1 CF of a method for calculating dielectric strength of binary environment-friendly mixed gas provided by an embodiment of the invention 3 SO 2 F mixture gas relative SF 6 Comparison of the predicted and test values of dielectric strength
Therefore, based on the method disclosed by the invention, a person skilled in the art can arbitrarily change the components of the environment-friendly binary mixed gas, and all the components fall into the protection scope of the invention.
The invention provides a method for calculating dielectric strength of binary environment-friendly mixed gas, which simultaneously considers intermolecular interaction on the premise of obtaining single molecule characteristic parameters, and provides a characterization method for synergistic effect of binary environment-friendly mixed gas and relative SF (sulfur hexafluoride) thereof 6 The dielectric strength calculating method solves the problems that in the prior art, only the dielectric strength of single gas can be predicted or the existing mixed gas insulating strength can be obtained only by adopting a test research method, but the dielectric strength of unknown binary mixed gas or newly configured binary mixed gas which is not subjected to test research can not be predicted, and provides basis and support for the design of environment-friendly mixed gas, the screening of buffer gas and the optimization of mixing proportion, so that the research of environment-friendly mixed gas scheme can be carried out more efficiently and pertinently, the research and development efficiency of environment-friendly insulating gas can be improved, the research risk and cost can be reduced, and manpower and material resources can be saved.
The foregoing description is directed to the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the invention, and all equivalent changes or modifications made under the technical spirit of the present invention should be construed to fall within the scope of the present invention.
Claims (8)
1. The calculating method of the dielectric strength of the binary environment-friendly mixed gas is characterized by comprising the following steps of:
s1, acquiring a single-molecule stable structure and single-molecule characteristic parameters of each component gas molecule in binary environment-friendly mixed gas to be detected;
s2, substituting single molecular characteristic parameters of each component gas into the constructed single gas relative SF 6 A dielectric strength calculation model of the gas to obtain the relative SF of the single-component gas 6 Dielectric strength of the gas; or obtaining the existing relative SF of the single-component gas by a power frequency breakdown test or a withstand voltage test 6 Dielectric strength of the gas;
s3, randomly generating a plurality of initial bimolecular cluster configurations formed by single-molecule stable structures of component gas, performing structural optimization on the initial bimolecular cluster configurations to obtain stable bimolecular configurations, and calculating to obtain Boltzmann distribution of the stable bimolecular configurations;
s4, taking the Boltzmann distribution proportion of the stable bimolecular configuration as a weight to obtain bimolecular characteristic parameters;
s5, substituting the bimolecular characteristic parameters into the constructed synergistic effect characterization coefficient prediction model to obtain a synergistic effect characterization coefficient of the mixed gas;
s6, relative SF from single component gas 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 Dielectric strength of the gas; binary environment-friendly mixed gas relative SF under high proportion section 6 The dielectric strength of the gas is obtained by linear fitting, so as to obtain the binary environment-friendly mixed gas relative SF in the range of 0-100 percent of the duty ratio 6 Is used for the dielectric strength of the steel sheet.
2. The method for calculating dielectric strength of binary environment-friendly mixed gas according to claim 1, wherein the single gas dielectric strength calculation model in step S2 is as follows:
E r-SF6 ＝0.41A s+ 2 +0.176f(E L )+0.445f(αχ)+0.028f(V s,max )-0.076
wherein E is r-SF6 Indicating the relative SF of the single gas 6 Dielectric strength of the gas; a is that s+ Representing the positive electrostatic potential surface area of such a single gas molecule; e (E) L Representing the lowest unoccupied orbital energy of such a single gas molecule; alpha represents the polarization rate; χ represents absolute electronegativity; v (V) s,max Representing the maximum value of the surface electrostatic potential of the single gas molecule;
wherein f (E) L )＝0.735E L -0.756 ，f(αχ)＝0.001(αχ) 2 +0.017αχ+0.089，f(V s,max )＝|-0.031V s,max 2 +1.032V s,max -0.011|。
3. The method for calculating dielectric strength of binary environment-friendly mixed gas according to claim 1, wherein the step S3 specifically comprises the following steps:
s31, adopting a cluster configuration search program, namely generating a plurality of initial double-molecule cluster configurations consisting of single-molecule stable structures of component gases by adopting a genmer in Molclus respectively at random;
s32, performing structural optimization and frequency verification calculation on the initial configuration of the bimolecular cluster by adopting a B3LYP/6-311G method to obtain a stable bimolecular configuration without virtual frequency;
s33, after the stable bimolecular configuration without the virtual frequency is obtained, removing the stable bimolecular configuration with similar energy and too high geometric structure similarity by using an isostat tool in Molclus, and setting the default value in the using program by parameters, namely, the energy threshold value for distinguishing clusters is 0.5kcal/mol, and the geometric threshold value for distinguishing clusters is
S34, calculating energy for stabilizing the bimolecular configuration by adopting a M06-2X/6-311+G method;
s35, constructing a Boltzmann distribution proportion calculation method for obtaining a stable bimolecular configuration:
wherein i, j is the number of stable bimolecular configuration, n i And n j Respectively represent the i < th > and j < th > stable bimolecular configurations, B i Is the proportion of the ith stable bimolecular configuration, E is the energy of the stable bimolecular configuration, and delta E i And delta E j The energy of the i and j stable bimolecular configurations and the energy minimum E in all stable bimolecular configurations are respectively min T is the temperature and R is the ideal gas constant.
4. The method for calculating the dielectric strength of the binary environment-friendly mixed gas according to claim 1, wherein in the step S4, the boltzmann distribution ratio of each stable bimolecular configuration obtained in the step S3 is taken as a weight to calculate bimolecular characteristic parameters of the stable bimolecular configuration respectively; the bimolecular characteristic parameter of the stable bimolecular configuration includes average binding energy delta E int-w Negative deviation of electrostatic potential, balance vAnd volume V, wherein the binding energy ΔE int During calculation, an equalization correction method is adopted to eliminate the overlapping error of the base group, delta E int-w For the weighted binding energy, n is the number of atoms in the bimolecular configuration.
5. The method for calculating dielectric strength of binary environment-friendly mixed gas according to claim 1, wherein the synergistic effect characterization coefficient prediction model in step S5 is as follows:
wherein N is a synergistic effect characterization coefficient.
6. As claimed in claim 1The method for calculating the dielectric strength of the binary environment-friendly mixed gas is characterized in that the dielectric strength of the binary environment-friendly mixed gas is calculated by the relative SF of single-component gas 6 Calculating the binary environment-friendly mixed gas relative SF of a low-proportion section by using the dielectric strength of the gas and the synergistic effect characterization coefficient of the mixed gas 6 The method for dielectric strength of the gas comprises the following steps:
the single gas obtained in the step S2 is processed with respect to SF 6 The dielectric strength of the (C) and the synergistic effect characterization coefficient N value obtained in S5 are substituted into the following formula to obtain the low-proportion binary environment-friendly mixed gas relative SF 6 Dielectric strength of gas:
wherein E is Mr-L 、E mr 、E bfr The two-element environment-friendly mixed gas, the environment-friendly electric affinity gas pure gas and the buffer gas pure gas relative SF 6 Dielectric strength, E Mr-L Refers to the relative SF of binary environment-friendly mixed gas in a low proportion section 6 Dielectric strength of (a); k is the molar ratio of the environment-friendly electric affinity gas in the mixed gas, and N is the synergistic effect characterization coefficient.
7. The method for calculating dielectric strength of binary environment-friendly mixed gas according to claim 1, wherein the low-proportion section in the step S6 refers to a part of the environment-friendly electric affinity gas, wherein the part of the environment-friendly electric affinity gas in the mixed gas accounts for 0 < k.ltoreq.20%; the high proportion section refers to the part of the environment-friendly electric affinity gas with the molar ratio k of 20 < k < 100% in the mixed gas.
8. The method for calculating dielectric strength of binary environment-friendly mixed gas according to claim 1, wherein the binary environment-friendly mixed gas relative SF in the high proportion section in the step S6 6 The use of linear fitting for dielectric strength of gas refers to the use of a binary environment-friendly mixed gas obtained in step S6 when the environment-friendly electric affinity gas is at a molar ratio of k=20% in the mixed gas to SF 6 Calculation result of dielectric strength of gas and step S2The obtained environment-friendly electric affinity gas single component gas relative SF 6 Is a linear fit of the dielectric strength of (c).
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