CN108872814B - Method for evaluating insulation life of oil paper in high-voltage current transformer - Google Patents
Method for evaluating insulation life of oil paper in high-voltage current transformer Download PDFInfo
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- 238000009413 insulation Methods 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 105
- 238000013519 translation Methods 0.000 claims abstract description 96
- 230000004913 activation Effects 0.000 claims abstract description 84
- 238000006243 chemical reaction Methods 0.000 claims abstract description 69
- 238000012360 testing method Methods 0.000 claims abstract description 69
- 230000032683 aging Effects 0.000 claims abstract description 60
- 229920002678 cellulose Polymers 0.000 claims abstract description 23
- 239000001913 cellulose Substances 0.000 claims abstract description 23
- 238000004364 calculation method Methods 0.000 claims abstract description 18
- 238000006116 polymerization reaction Methods 0.000 claims description 43
- 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 31
- 238000011156 evaluation Methods 0.000 claims description 21
- 230000008859 change Effects 0.000 claims description 12
- 230000035484 reaction time Effects 0.000 claims description 8
- 239000000123 paper Substances 0.000 abstract description 126
- 239000011087 paperboard Substances 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 9
- 238000004590 computer program Methods 0.000 description 7
- 230000006870 function Effects 0.000 description 4
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 238000009421 internal insulation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000003878 thermal aging Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012854 evaluation process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001453 impedance spectrum Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
Abstract
The invention relates to a method for evaluating the insulation life of oil paper in a high-voltage current transformer. The invention provides an effective numerical calculation method for evaluating the insulation life of the oil paper in the high-voltage current transformer, and the translation reduction is carried out by applying the oil paper insulation dielectric loss factor curves tested at different temperatures to obtain a temperature translation factor; obtaining the activation energy of the oil-immersed paperboard with the corresponding water content according to the calculated temperature translation factor; repeating the calculation process of the activation energy of the oil-immersed paperboard, and establishing the relationship between the activation energy and the water content of the oil-immersed paperboard; and finally, the aging state of the oil paper insulation in the high-voltage current transformer can be accurately evaluated by combining a reaction kinetic model of cellulose aging in the oil paper insulation. The invention realizes the service life prediction of the oiled paper with different test temperatures and different water contents.
Description
Technical Field
The invention belongs to the field of oil paper insulation life assessment, and particularly relates to an oil paper insulation life assessment method in a high-voltage current transformer.
Background
The high-voltage current transformer is an important link in the operation of a power grid, but due to the influence of a complex operation environment (moisture content, aging temperature and the like) all the year round, the oil paper insulation part in the high-voltage current transformer is seriously aged, the insulation performance of the high-voltage current transformer is greatly reduced, and the stability of the power grid is seriously influenced, so that the service life of the high-voltage current transformer depends on the aging degree of the oil paper insulation in the high-voltage current transformer, and the research on an evaluation algorithm for the aging life of the internal insulation in the high-voltage current transformer has.
For oil paper insulation equipment, the degree of reduction of the degree of polymerization of the insulation paper board becomes an important index for judging the service life of the equipment, but for high-voltage current transformer equipment, the aging degree of internal insulation is evaluated through sampling test, the service life is complex, the operation is not easy, the test result is more inaccurate due to the difference of temperature and moisture content, the measurement error is extremely large, quantitative analysis is needed to be carried out on the degree of reduction of the insulation performance of the oil paper in the high-voltage current transformer, and therefore the service life of the high-voltage current transformer is accurately evaluated.
The method provided by the IEEE standard C57.91 and the IEC standard 600767 is adopted to predict the residual life of the oiled paper insulation internationally, the insulation life is effectively and directly predicted according to the change trend of the hot spot temperature inside the oiled paper insulation and the polymerization degree of the insulation paper board, the calculation method is simple, the influence of other factors such as water content is not considered, the calculation of the oil paper insulation life is single, and an effective calculation method for engineering practice is not formed at present.
The invention patent CN 201310066515-a method for evaluating the aging state of oiled paper insulation, although the frequency-temperature translation theory is used and the activation energy is calculated through frequency-temperature translation, the method is mainly used for calculating the translation factor, the translation factor is expressed through the activation energy and the temperature, and further the dielectric loss curves at different temperatures are obtained, so that the influence of the temperature is eliminated. The patent mainly measures the dielectric spectrum in the aged state, and estimates the aged state by fitting the algebraic relation between the degree of polymerization and the dielectric constant and the dielectric loss.
The invention patent CN 201310134298-transformer oiled paper insulation aging evaluation and life prediction device and prediction method thereof measure polymerization degree indexes of aged transformer insulated paper and insulated paper board samples, perform mechanical strength test on the insulated paper, analyze furfural concentration change in oil in the insulating paper aging process, test moisture content in the paper and paper board aging process, and test gas content in the oil. The polymerization degree, the mechanical strength, the furfural, the water in the aging process and the gas in the oil are detected, and the service life is evaluated according to the parameters.
The evaluation of the service life of the insulating paperboard with different initial water contents under an unaged state is not reported at present, so a novel technical scheme is urgently needed to solve the problem in the prior art.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for evaluating the service life of the oil paper insulation in the high-voltage current transformer is used for solving the technical problem that an effective service life calculation method for the oil paper insulation is not formed at present and is used for engineering practice.
A method for evaluating the insulation life of oil paper in a high-voltage current transformer comprises the following steps in sequence:
step one, obtaining a dielectric loss factor curve of the oiled paper with known water content at a set translation reference temperature; obtaining a dielectric loss factor curve of the oiled paper with the same water content at a set test temperature;
step two, obtaining a translation factor theoretical expression of the oilpaper with the water content according to a dielectric loss factor curve of the oilpaper with the known water content at a translation reference temperature and a test temperature, a translation factor formula and an expression of the activation energy delta E of the fitted oilpaper; the translation factor formula is as follows:
wherein: a is a translation factor under the corresponding water content; t isrefIs a reference temperature in units of: k; t is the test temperature, in units of: k; delta E is the activation energy of the oiled paper; r is the gas molecular constant, and R is the gas molecular constant,
8.314J/(mol·K)；
thirdly, performing an accelerated aging test on the oiled paper at a set aging reference temperature to obtain an oiled paper polymerization degree value corresponding to the aging time at the aging reference temperature, and drawing an aging time and polymerization degree change curve at the aging reference temperature;
step four, according to the aging time and polymerization degree change curve in the step three, combining a cellulose chemical reaction kinetic equation and a chemical reaction rate equation to carry out curve fitting, and obtaining correlation coefficients in the cellulose chemical reaction kinetic equation and the chemical reaction rate equation: k is a radical of2、k10And b is the value of, wherein k10Is an initial value of the reaction rate k (t), k2And b is the fitting coefficient to be determined; the chemical reaction kinetic equation of the cellulose is as follows:
the chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswShowing the influence of the water content on the reaction rate, whereinA. b is a parameter to be fitted, T is a test temperature, and the unit is as follows: k; delta E is the activation energy of the oiled paper; r is a gas molecular constant of 8.314J/(mol.K);
wherein: DPtThe degree of polymerization at time t; DP0The polymerization degree at the initial time; k (t) is the reaction rate; k is a radical of10Is the initial value of k (t); k is a radical of2And b is a parameter to be fitted; t is the reaction time;
step five, obtaining k10Translating according to the translation factor theoretical expression obtained in the step two to obtain a translated reaction rate initial value k'10：
Step six, according to the initial value k 'of the reaction rate after translation in the step five'10And fitting coefficient k in step four2And b, obtaining an evaluation equation of the insulation life L of the oil paper, and solving the equation to obtain an insulation life L evaluation value of the oil paper with known water content in the high-voltage current transformer at a set test temperature.
And in the second step, the activation energy delta E of the fitted oil paper is obtained by fitting a fitting curve of the relation between the activation energy and the water content of the oil paper, and the activation energy delta E expression of the fitted oil paper is as follows:
ΔE＝Aexp(w/B)+C
wherein, the delta E is the activation energy of the oiled paper, the unit of the delta E is kJ/mol, the w is the water content of the oiled paper, the unit of the w is%, and A, B, C are all the fitting parameters to be determined.
The method for obtaining the fitting curve of the relation between the activation energy and the water content of the oil paper comprises the following steps:
① taking the difference value of the dielectric loss factor of the test temperature and the dielectric loss factor of the translation reference temperature of the oiled paper with the same water content and the dielectric loss factor of the translation reference temperature at the same frequency as the translation factor value corresponding to the test temperature of the oiled paper with the same water content;
② obtaining the activation energy value of the oilpaper with the same water content by slope calculation according to the translation factor value and the translation factor formula, taking the average value of the activation energy values as the activation energy delta E of the oilpaper, and the unit is kJ/mol, and obtaining the activation energy value of the oilpaper with each water content;
③ according to the obtained activation energy of the oiled paper under each water content, a fitting curve with the abscissa as the water content of the oiled paper and the ordinate as the relation between the activation energy of the oiled paper and the water content is established.
The theoretical expression of the translation factor in the second step is as follows:
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k; t is the test temperature, in units of: k; delta E is the activation energy of the oiled paper, and the unit is kJ/mol, R is the gas molecular constant, 8.314J/(mol.K); w is the moisture content of the oiled paper; A. b, C are all to be determined fitting parameters.
The initial value k 'of the reaction rate after translation in the step five'10Comprises the following steps:
k1'0＝αk10
wherein k is10Is the initial value of k (t), and k (t) is the reaction rate;
the evaluation equation of the insulation life L of the oiled paper obtained in the sixth step is as follows:
wherein: DPtDegree of polymerization at time t, DP0Degree of polymerization at the initial time, k10Is an initial value of k (t), k (t) is a reaction rate, k2Is constant, T is reaction time, α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k and delta E are activation energy of the oilpaper, the unit of the activation energy is kJ/mol, R is a gas molecular constant, 8.314J/(mol. K), w is the moisture content of the oilpaper, and the unit of the moisture content is%, A, B, C, b is a parameter to be fitted.
An apparatus for evaluating the insulation life of oil paper in a high-voltage current transformer comprises:
the first obtaining module is used for obtaining dielectric loss factor curves at the translation reference temperature and the test temperature;
the second obtaining module is used for obtaining a translation factor theoretical expression of the oilpaper with each water content;
the third obtaining module is used for obtaining the oil paper aging time at the aging reference temperature, the oil paper polymerization degree value corresponding to the aging time and a change curve of the aging time and the polymerization degree;
the fourth obtaining module is used for obtaining correlation coefficients in a chemical reaction kinetic equation and a chemical reaction rate equation of the cellulose: k is a radical of2、k10And b, the kinetic equation for the chemical reaction of cellulose is:
the chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswAnd (3) expressing the influence of the water content on the reaction rate, wherein A, b is a parameter to be fitted, and T is a test temperature, and the unit of the temperature is as follows: k; delta E is the activation energy of the oiled paper; r is a gas molecular constant of 8.314J/(mol.K);
wherein: DPtThe degree of polymerization at time t; DP0The polymerization degree at the initial time; k (t) is the reaction rate; k is a radical of10Is the initial value of k (t); k is a radical of2And b is a parameter to be fitted; t is the reaction time;
a fifth obtaining module for obtaining an initial value k 'of the reaction rate after translation'10；
And the sixth obtaining module is used for obtaining the insulation life evaluation value of the high-voltage current transformer internal oil paper with known water content at the set test temperature through the evaluation equation of the insulation life of the high-voltage current transformer internal oil paper.
The invention has the beneficial effects that:
the invention provides an effective numerical calculation method for evaluating the insulation life of the oil paper in the high-voltage current transformer, and the translation reduction is carried out by applying the oil paper insulation dielectric loss factor curves tested at different temperatures to obtain a temperature translation factor; obtaining the corresponding moisture content oilpaper activation energy according to the calculated temperature translation factor; repeating the calculation process of the activation energy of the oilpaper, and establishing the relationship between the activation energy of the oilpaper and the water content; and finally, the aging state of the oil paper insulation in the high-voltage current transformer can be accurately evaluated by combining a reaction kinetic model of cellulose aging in the oil paper insulation.
The invention realizes the service life prediction of the oiled paper with different test temperatures and different water contents, and the service life of the oiled paper with different aging temperatures and different water contents can be deduced through an established formula after a group of accelerated aging tests are obtained.
Calculation of the translation factor was proposed early as a frequency-temperature translation or a time-temperature translation. The method is different in that the water content of the insulating paperboard is searched for, the activation energy is replaced by the water content by finding out the mathematical relationship between the water content and the activation energy, and then the translation factor is represented again through the water content. And the translation factor is used for translating the reaction rate of the cellulose dynamic model to realize the prediction of the service life of the oil paper.
Description of the drawings:
FIG. 1 is a flow chart of a method for evaluating the insulation life of oil paper inside a high-voltage current transformer according to the present invention;
FIG. 2 is dielectric loss data and corresponding fitting curves of oiled paper with a water content of 1.2% at different test temperatures in the embodiment of the invention;
FIG. 3 is a calculated curve of activation energy of oiled paper with water content of 1.2% according to the embodiment of the present invention;
FIG. 4 is a fitting curve of the relation between the activation energy and the water content of the oiled paper in the embodiment of the invention;
FIG. 5 is a graph showing the variation of the polymerization degree of the oiled paper with aging time in the accelerated aging test at 130 ℃ in the example of the present invention;
FIG. 6 is a curve fitted to the reaction kinetics equation of cellulose in the example of the present invention.
Detailed Description
A method for evaluating the insulation life of oil paper in a high-voltage current transformer is shown in figure 1 and comprises the following steps:
setting a reference temperature, inputting the water content of the oiled paper, obtaining dielectric loss factor values corresponding to all frequency points of the oiled paper with the known water content at the reference temperature, and sequentially connecting all the values by using a smooth curve to obtain a dielectric loss factor curve at the translation reference temperature;
setting the test temperature, obtaining the dielectric loss factor values corresponding to the frequency points of the oiled paper with the same water content at the test temperature, and sequentially connecting the values by using a smooth curve to obtain the dielectric loss factor curve of the oiled paper with the same water content at the test temperature.
The dielectric loss factor curves of the oiled paper at different test temperatures and under the same water content are shown in fig. 2, wherein the abscissa of the dielectric loss factor curve is frequency, and the ordinate is the dielectric loss factor.
Calculating the value of the translation factor under the corresponding water content by taking the difference value of the dielectric loss factor under the test temperature and the dielectric loss factor under the translation reference temperature of the specific frequency point in the graph 2;
step two, substituting the translation factor value in the step one into a translation factor formula, and calculating the activation energy value of the oilpaper under the same water content through the slope, wherein the average value of the activation energy values is the activation energy delta E of the oilpaper;
the formula of the translation factor is as follows,
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k, delta E is the activation energy of the oiled paper, the unit of the activation energy is kJ/mol, R is the gas molecular constant, 8.314J/(mol K);
because the activation energy of the same paper board is the same, the activation energy calculated by the slope obtained after translation has a certain difference in size, the average activation energy is obtained by taking the average value for calculation, and the average activation energy is considered as the activation energy delta E of the oil-immersed paper board;
repeating the calculation process of the translation factor and the activation energy, calculating the activation energy of the oilpaper with different water contents according to the test results under different water contents, and establishing a fitting curve of the activation energy of the oilpaper and the water content of the oilpaper, wherein the activation energy delta E expression of the oilpaper after the fitting of the fitting curve is as follows:
ΔE＝Aexp(w/B)+C
wherein, Delta E is the activation energy of the oiled paper and has the unit of kJ/mol, w is the water content of the oiled paper and has the unit of%, A, B, C are all the fitting parameters to be determined;
establishing a translation factor theoretical expression related to the test temperature and the moisture content of the oiled paper according to the calculation result as follows;
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k; t is the test temperature, in units of: k; delta E is the activation energy of the oiled paper, and the unit is kJ/mol, R is the gas molecular constant, 8.314J/(mol.K); w is the moisture content of the oiled paper; A. b, C are all fitting parameters to be determined;
step three, carrying out an accelerated thermal aging test on the oiled paper with known water content, wherein an aging reference temperature can be set automatically, acquiring the aging time of the oiled paper at the set aging reference temperature and the polymerization degree value of the oiled paper corresponding to the aging time, drawing a change curve of the aging time and the polymerization degree,
the abscissa of the change curve of the aging time and the polymerization degree is the aging time, and the ordinate is the polymerization degree;
step four, according to the test data obtained in the step three, curve fitting is carried out by combining a cellulose chemical reaction kinetic equation and a chemical reaction rate equation, and the correlation coefficient in the cellulose chemical reaction kinetic equation can be obtained: k is a radical of2、k10And b, wherein k10Is an initial value of k (t), k2B is a fitting coefficient to be determined;
the chemical reaction kinetic equation of the cellulose is as follows:
wherein: DPtDegree of polymerization at time t, DP0The degree of polymerization at the initial time, and k (t) the reaction rate; k is a radical of10Is an initial value of k (t), k2And b is the parameter to be fitted and t is the reaction time.
The chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswAnd (3) expressing the influence of the water content on the reaction rate, wherein A, b is a parameter to be fitted, and T is a test temperature, and the unit of the temperature is as follows: k; delta E is the activation energy of the oiled paper, and the unit is kJ/mol; r is a gas molecular constant of 8.314J/(mol.K);
step five, according to k obtained in step four10Translating the translation factor theoretical expression in the step two to obtain a translated reaction rate initial value k'10：
k′10＝αk10
Wherein k is10Is the initial value of k (t), and k (t) is the reaction rate;
step six, according to the initial value k 'of the reaction rate after translation in the step five'10And the undetermined fitting coefficient k obtained in the fourth step2B, obtaining an evaluation equation of the insulation life L of the oil paper, and obtaining an insulation life L evaluation value of the oil paper with known water content in the high-voltage current transformer at a set test temperature by solving the equation;
the evaluation equation of the insulation life L of the oiled paper is as follows:
wherein: DPtDegree of polymerization at time t, DP0Degree of polymerization at the initial time, k10Is an initial value of k (t), k (t) is a reaction rate, k2Is constant, T is reaction time, α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k and delta E are activation energy of the oilpaper, the unit of the activation energy is kJ/mol, R is a gas molecular constant, 8.314J/(mol. K), w is the moisture content of the oilpaper, and the unit of the moisture content is%, A, B, C, b is a parameter to be fitted.
An apparatus for evaluating the insulation life of oil paper in a high-voltage current transformer comprises:
the first obtaining module is used for obtaining dielectric loss factor curves at the translation reference temperature and the test temperature;
the second obtaining module is used for obtaining a translation factor theoretical expression of the oilpaper with each water content;
the method for obtaining the translation factor theoretical expression comprises the following steps: taking the difference value of the dielectric loss factor of the test temperature at the same frequency and the dielectric loss factor of the reference temperature to obtain a translation factor value corresponding to the test temperature of the oilpaper at the same water content; substituting the translation factor value into a translation factor formula, and calculating the activation energy value of the oilpaper under the same water content through slope, wherein the average value of the activation energy values is the activation energy delta E of the oilpaper; repeating the calculation process of the translation factor and the activation energy to obtain the activation energy of the oilpaper with different water contents, establishing a fitting curve of the activation energy of the oilpaper and the water content of the oilpaper, and fitting the fitting curve to obtain an activation energy delta E expression of the oilpaper; substituting the fitted activation energy delta E expression of the oilpaper into a translation factor formula to obtain a translation factor theoretical expression;
the formula of the translation factor is as follows,
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k, Delta E are the activity of oiled paperChemical energy, which is expressed in kJ/mol, R is a gas molecular constant, 8.314J/(mol. K);
the activation energy delta E expression of the oiled paper after fitting the fitting curve is as follows:
ΔE＝Aexp(w/B)+C
wherein, Delta E is the activation energy of the oiled paper, the unit of the Delta E is kJ/mol, w is the water content of the oiled paper, and the unit of the W is percent, A, B, C is all parameters to be fitted;
the translation factor theoretical expression is as follows;
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k; t is the test temperature, in units of: k; delta E is the activation energy of the oiled paper, and the unit is kJ/mol, R is the gas molecular constant, 8.314J/(mol.K); w is the moisture content of the oiled paper; A. b, C are all fitting parameters to be determined;
the third obtaining module is used for obtaining the oil paper aging time at the aging reference temperature, the oil paper polymerization degree value corresponding to the aging time and a change curve of the aging time and the polymerization degree;
and the fourth obtaining module is used for performing curve fitting on the aging time and polymerization degree change curve by combining a cellulose chemical reaction kinetic equation and a chemical reaction rate equation to obtain a correlation coefficient in the cellulose chemical reaction kinetic equation: k is a radical of2、k10And b is the value of, wherein k10Is an initial value of the reaction rate k (t), k2And b is the fitting coefficient to be determined;
the chemical reaction kinetic equation of the cellulose is as follows:
wherein: DPtDegree of polymerization at time t, DP0The degree of polymerization at the initial time, and k (t) the reaction rate; k is a radical of10Is an initial value of k (t), k2And b is the parameter to be fitted, t isReaction time;
the chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswAnd (3) expressing the influence of the water content on the reaction rate, wherein A, b is a parameter to be fitted, and T is a test temperature, and the unit of the temperature is as follows: k; delta E is the activation energy of the oiled paper, and the unit is kJ/mol; r is a gas molecular constant of 8.314J/(mol.K);
a fifth obtaining module for obtaining an initial value k of the reaction rate k (t)10Translating according to a translation factor theoretical expression to obtain an initial value k 'of the translated reaction rate'10；
And the sixth obtaining module is used for obtaining the insulation life evaluation value of the oil paper with known water content in the high-voltage current transformer at the set test temperature through the oil paper insulation life evaluation equation.
The evaluation equation of the insulation life L of the oiled paper is as follows:
wherein: DPtDegree of polymerization at time t, DP0Degree of polymerization at the initial time, k10Is an initial value of k (t), k (t) is a reaction rate, k2Is constant, T is reaction time, α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k and delta E are activation energy of the oilpaper, the unit of the activation energy is kJ/mol, R is a gas molecular constant, 8.314J/(mol. K), w is the moisture content of the oilpaper, and the unit of the moisture content is%, A, B, C, b is a parameter to be fitted.
The oil paper is the oil paper in the high-voltage current transformer.
Example (b):
the evaluation process of the insulation life of the oil paper in the high-voltage current transformer is as follows:
under laboratory conditions, ordinary insulating paper boards and No. 45 naphthenic transformer mineral insulating oil are used for manufacturing oiled paper, the paper boards naturally absorb moisture, and subsequent tests are carried out under different moisture contents (0.17%, 1.2%, 2.7% and 3.2%);
testing the frequency domain dielectric loss curve of the oiled paper with different water contents at the temperature of 40 ℃, 60 ℃, 80 ℃ and 100 ℃ by using a testing instrument, and selecting an oiled paper testing curve with the water content of 1.2 percent as shown in figure 2; taking 40 ℃ as a translation reference temperature, respectively carrying out translation calculation on dielectric loss curves of 60 ℃, 80 ℃ and 100 ℃ to obtain translation factors at corresponding test temperatures, and calculating the activation energy of the water-containing oil paper according to the relation between the translation factors and the test temperatures, as shown in fig. 3 (the activation energy of the water-containing oil paper can be calculated by fitting the slope of the curve in the diagram); repeating the above method for calculating the activation energy of the water-containing oil paper to obtain the activation energy of different water-containing oil papers (0.17%, 2.7%, 3.2%), establishing the relationship between the activation energy of the oil paper and the water content, as shown in fig. 4, fitting by using an exponential equation, wherein the fitting calculation result is as follows:
ΔE＝1.247exp(w/0.01288)+79.45
and establishing a theoretical expression of the translation factor related to the test temperature and the moisture content of the oiled paper according to the calculation result:
wherein α is the translation factor under corresponding water content, TrefIs a reference temperature in units of: k, T is the test temperature in units of: k and R are gas molecular constants of 8.314J/(mol. K), and w is the moisture content of the oiled paper and the unit is%.
In order to obtain the service life data of the oiled paper at the accelerated aging reference temperature, an accelerated thermal aging test at 130 ℃ is carried out under the laboratory condition to obtain a variation curve of the polymerization degree of the oiled paper along with the aging time, as shown in fig. 5; obtaining a data fitting curve according to the aging test data at 130 ℃, and obtaining a correlation coefficient in a chemical reaction kinetic equation of the cellulose according to the data fitting equation, as shown in fig. 6, wherein: k is a radical of2＝6.72×10-5，k10＝2.21×10-5And b is 1.5-1.7, so that the translation factor expression related to the aging temperature and the moisture content of the oiled paper is obtained, and the service life L evaluation equation of the oiled paper can be obtained:
wherein: DPtDegree of polymerization at time t, DP0α is the translation factor under the corresponding water content, T is the test temperature, the unit is K, R is the gas molecular constant, 8.314J/(mol.K), w is the water content of the oilpaper, and the unit is%.
When the water content is 0.5% and the temperature is 70 ℃, and the evaluation equation of the service life L of the oiled paper is substituted, the translation factor is calculated to obtain:
the lifetime was calculated as:
according to the method for evaluating the insulation life of the oil paper in the high-voltage current transformer, the aging life of an oil paper insulation system at any aging temperature and water content can be calculated, when the water content is 0.5% and the temperature is 70 ℃, the insulation life of the oil paper is 30 years and the service life of a corresponding transformer can be 30 years, and the method has important significance for evaluating the service life of oil paper insulation equipment.
Firstly, setting a reference temperature according to a dielectric loss factor curve of the oiled paper under certain water content under several temperatures, calculating a translation factor of the dielectric loss curve at different temperatures to the reference temperature according to a translation formula, calculating the average activation energy of the corresponding oiled paper through the translation factor, repeating the experiment, testing the average activation energy of the oiled paper with different water contents, and thus establishing a corresponding relation between the activation energy of the oiled paper and the water content in the oiled paper, and obtaining a theoretical expression of a translation factor a related to the temperature and the water content; secondly, obtaining an aging curve of cellulose aging reaction in the oilpaper insulation at a reference temperature through an accelerated aging test of the oilpaper, and determining a correlation coefficient in a model by combining a test result with a reaction kinetic model of cellulose to obtain a theoretical expression of a service life model; and finally, combining the translation factor a with a service life model of the oil paper in the oil paper insulation, and obtaining a theoretical expression capable of calculating the service life of the oil paper at different temperatures and different water contents through a reaction rate equation.
The present invention is not described in detail, but is known to those skilled in the art. As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may 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, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may 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, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the scope of protection thereof, and although the present application is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: numerous variations, modifications, and equivalents will occur to those skilled in the art upon reading the present application and are within the scope of the claims appended hereto.
Claims (7)
1. The method for evaluating the insulation life of the oil paper in the high-voltage current transformer is characterized by comprising the following steps in sequence:
step one, obtaining a dielectric loss factor curve of the oiled paper with known water content at a set translation reference temperature; obtaining a dielectric loss factor curve of the oiled paper with the same water content at a set test temperature;
step two, obtaining a translation factor theoretical expression of the oilpaper with the water content according to a dielectric loss factor curve of the oilpaper with the known water content at a translation reference temperature and a test temperature, a translation factor formula and an expression of the activation energy delta E of the fitted oilpaper; the translation factor formula is as follows:
wherein α is translation factor under corresponding water content, TrefIs a reference temperature in units of: k; t is the test temperature, in units of: k; delta E is the activation energy of the oiled paper; r is a gas molecular constant of 8.314J/(mol.K);
thirdly, performing an accelerated aging test on the oiled paper at a set aging reference temperature to obtain an oiled paper polymerization degree value corresponding to the aging time at the aging reference temperature, and drawing an aging time and polymerization degree change curve at the aging reference temperature;
step four, according to the aging time and polymerization degree change curve in the step three, combining a cellulose chemical reaction kinetic equation and a chemical reaction rate equation to carry out curve fitting, and obtaining correlation coefficients in the cellulose chemical reaction kinetic equation and the chemical reaction rate equation: k is a radical of2、k10And b is the value of, wherein k10Is an initial value of the reaction rate k (t), k2And b is the fitting coefficient to be determined; the chemical reaction kinetic equation of the cellulose is as follows:
the chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswShowing the influence of the water content on the reaction rate, wherein w is the water content of the oil paper, and A is a parameter to be fitted;
wherein: DPtThe degree of polymerization at time t; DP0The polymerization degree at the initial time; t is the reaction time;
step five, obtaining k10Translating according to the translation factor theoretical expression obtained in the step two to obtain a translated reaction rate initial value k'10；
Step six, according to the initial value k 'of the reaction rate after translation in the step five'10And fitting coefficient k in step four2And b, obtaining an evaluation equation of the insulation life L of the oil paper, and solving the equation to obtain an insulation life L evaluation value of the oil paper with known water content in the high-voltage current transformer at a set test temperature.
2. The method for evaluating the insulation life of the oil paper in the high-voltage current transformer according to claim 1, wherein the method comprises the following steps: and in the second step, the activation energy delta E of the fitted oil paper is obtained by fitting a fitting curve of the relation between the activation energy and the water content of the oil paper, and the activation energy delta E expression of the fitted oil paper is as follows:
ΔE＝A exp(w/B)+C
b, C are all parameters to be fitted.
3. The method for evaluating the insulation life of the oil paper in the high-voltage current transformer according to claim 2, wherein the method comprises the following steps: the method for obtaining the fitting curve of the relation between the activation energy and the water content of the oil paper comprises the following steps:
① taking the difference value of the dielectric loss factor of the test temperature and the dielectric loss factor of the translation reference temperature of the oiled paper with the same water content and the dielectric loss factor of the translation reference temperature at the same frequency as the translation factor value corresponding to the test temperature of the oiled paper with the same water content;
② obtaining the activation energy value of the oilpaper with the same water content by slope calculation according to the translation factor value and the translation factor formula, and obtaining the activation energy value of the oilpaper with each water content by taking the average value of the activation energy values as the activation energy delta E of the oilpaper;
③ according to the obtained activation energy of the oiled paper under each water content, a fitting curve with the abscissa as the water content of the oiled paper and the ordinate as the relation between the activation energy of the oiled paper and the water content is established.
4. The method for evaluating the insulation life of the oil paper in the high-voltage current transformer according to claim 2, wherein the method comprises the following steps: the theoretical expression of the translation factor in the second step is as follows:
5. the method for evaluating the insulation life of the oil paper in the high-voltage current transformer according to claim 1, wherein the method comprises the following steps: the initial value k 'of the reaction rate after translation in the step five'10Comprises the following steps:
k′10＝αk10。
6. the method for evaluating the insulation life of the oil paper in the high-voltage current transformer according to claim 2, wherein the evaluation equation for obtaining the insulation life of the oil paper L in the sixth step is as follows:
7. the utility model provides a device of inside oiled paper insulation life-span aassessment of high-voltage current transformer, characterized by: the method comprises the following steps:
the first obtaining module is used for obtaining dielectric loss factor curves at the translation reference temperature and the test temperature;
the second obtaining module is used for obtaining a translation factor theoretical expression of the oilpaper with each water content;
the third obtaining module is used for obtaining the oil paper aging time at the aging reference temperature, the oil paper polymerization degree value corresponding to the aging time and a change curve of the aging time and the polymerization degree;
the fourth obtaining module is used for obtaining correlation coefficients in a chemical reaction kinetic equation and a chemical reaction rate equation of the cellulose: k is a radical of2、k10And b, the kinetic equation for the chemical reaction of cellulose is:
the chemical reaction rate equation is:
k＝Abwexp(-ΔE/RT)
wherein b iswAnd (3) representing the influence of the water content on the reaction rate, wherein w is the water content of the oiled paper, A, b is a parameter to be fitted, T is the test temperature, and the unit is as follows: k; delta E is the activation energy of the oiled paper; r is a gas molecular constant of 8.314J/(mol.K);
wherein: DPtThe degree of polymerization at time t; DP0The polymerization degree at the initial time; k (t) is the reaction rate; k is a radical of10Is the initial value of k (t); k is a radical of2And b is a parameter to be fitted; t is the reaction time;
a fifth obtaining module for obtaining an initial value k 'of the reaction rate after translation'10；
And the sixth obtaining module is used for obtaining the insulation life evaluation value of the oil paper with known water content in the high-voltage current transformer at the set test temperature through the oil paper insulation life evaluation equation.
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| CN109870635B (en) * | 2019-03-04 | 2020-11-10 | 国网陕西省电力公司电力科学研究院 | Oiled paper insulation aging state evaluation method and system based on activation energy iterative correction |
| CN110297167B (en) * | 2019-07-17 | 2022-04-26 | 国网浙江省电力有限公司电力科学研究院 | Transformer aging state evaluation method based on multi-source information fusion |
| CN110889228B (en) * | 2019-11-28 | 2023-04-18 | 国网吉林省电力有限公司电力科学研究院 | Transformer oil paper insulation aging prediction method based on chicken swarm optimization BP neural network |
| CN110889234B (en) * | 2019-12-04 | 2023-04-07 | 国网吉林省电力有限公司电力科学研究院 | Aging life evaluation method for internal insulation oil paper of oil-immersed transformer |
| CN111596181B (en) * | 2020-05-28 | 2022-05-06 | 华北电力大学（保定） | Transformer solid insulation aging evaluation method based on bubble escape temperature |
| CN111638429A (en) * | 2020-06-09 | 2020-09-08 | 国网山东省电力公司电力科学研究院 | Temperature correction method and device for insulating material state evaluation |
| CN112595939B (en) * | 2020-12-02 | 2021-08-13 | 西南交通大学 | Method for eliminating dielectric spectrum temperature effect of oiled paper insulation frequency domain in low-temperature environment |
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