CN115128385A - Aging life evaluation method for insulating medium of high-voltage reactor - Google Patents
Aging life evaluation method for insulating medium of high-voltage reactor Download PDFInfo
- Publication number
- CN115128385A CN115128385A CN202210821418.3A CN202210821418A CN115128385A CN 115128385 A CN115128385 A CN 115128385A CN 202210821418 A CN202210821418 A CN 202210821418A CN 115128385 A CN115128385 A CN 115128385A
- Authority
- CN
- China
- Prior art keywords
- aging
- test
- test sample
- sample
- relaxation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
- G01R31/003—Environmental or reliability tests
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/08—Fluids
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/04—Ageing analysis or optimisation against ageing
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Geometry (AREA)
- General Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Testing Relating To Insulation (AREA)
Abstract
The invention discloses an aging life evaluation method of an insulating medium of a high-voltage reactor, which relates to the technical field of aging life detection of solid dielectrics, and comprises the steps of obtaining a test sample, determining the aging test temperature of the test sample according to a simulation model, and establishing an aging test circuit of the test sample; and then aging the test sample based on the aging test temperature and the aging test circuit, establishing a test sample aging life evaluation model by analyzing the dielectric characteristic data of the aged test sample, and finally evaluating the service life of the insulation medium of the high-voltage reactor according to the obtained test sample aging life evaluation model. The technical problem that the aging life of the epoxy resin cannot be accurately obtained by evaluating the aging state of the epoxy resin in the high-voltage reactor by adopting an empirical formula in the prior art is solved.
Description
Technical Field
The invention relates to the technical field of aging life detection of solid dielectrics, in particular to an aging life evaluation method for solid dielectrics of a high-voltage reactor.
Background
With the increasing number of high-voltage reactors, the insulation problem of the high-voltage reactor is more and more emphasized by people. Epoxy resin is most common in the insulation system of the current high-voltage reactor due to a plurality of unique advantages of high insulation performance, large structural strength, good sealing performance and the like, but epoxy resin is easily affected by factors such as high heat, electric field, ultraviolet rays and the like to generate photo-oxidation and thermal aging. The thermal aging is an important reason for deterioration and failure of the epoxy resin, the epoxy resin macromolecular chains are broken by high heat to generate oxidative decomposition, more polar small molecules are generated, the relaxation polarization loss is increased, and the aged epoxy resin generates new defects due to thermal expansion of air gaps in the epoxy resin under a high-heat environment for a long time. In addition, the electric field is another important cause of deterioration failure of the epoxy resin, electrical aging occurs inside the epoxy resin under the continuous action of the electric field, the probability of partial discharge is increased due to defects generated by the electrical aging, and the quality of the insulation performance of the epoxy resin directly determines the service life of the transformer. In order to ensure the safe and stable operation of the high-voltage reactor, the aging state of the epoxy resin in the high-voltage reactor needs to be detected, and the aging life of the epoxy resin is evaluated according to the detection result.
Since the aging state detection of the internal epoxy resin of the high-voltage reactor is dangerous when the high-voltage reactor is put into use, the aging life of the epoxy resin cannot be evaluated by directly detecting the aging state of the internal epoxy resin of the high-voltage reactor before an accident occurs to the high-voltage reactor. At present, transformer substation operators adopt an empirical method to return the reactor to a factory for maintenance, spray insulating paint on the outer surface of the reactor, and return the reactor to the transformer substation for installation and operation after the reactor is qualified in a voltage withstand test. But the insulation condition of the internal epoxy resin after electric heating aging is not known, and the aging life of the epoxy resin is estimated completely by the experience or empirical formula of a maintainer.
The evaluation of the aging life of the epoxy resin in the high-voltage reactor by depending on experience is obviously random, and most of experience formulas apply statistical rules, so that the aging life of the epoxy resin cannot be accurately obtained.
Disclosure of Invention
The invention provides an aging life evaluation method for an insulating medium of a high-voltage reactor, which is used for solving the technical problem that the aging life of epoxy resin cannot be accurately obtained by evaluating the aging state of the epoxy resin in the high-voltage reactor by adopting an empirical formula in the prior art.
The invention provides a method for evaluating the aging life of an insulating medium of a high-voltage reactor, which comprises the following steps:
obtaining a test sample of the high-voltage reactor insulating medium;
determining the aging test temperature of the test sample according to the simulation model;
establishing an aging test circuit of the test sample;
establishing an aging environment based on the aging test temperature and the aging test circuit, placing the test sample in the aging environment for aging, and obtaining dielectric property data of the aged test sample;
and establishing a test sample aging life evaluation model based on the dielectric characteristic data, and evaluating the service life of the insulation medium of the high-voltage reactor according to the test sample aging life evaluation model.
Preferably, the simulation model includes a series reactor loss model, a temperature field heat dissipation model and a fluid heat dissipation model, and the determining the aging test temperature of the test sample according to the simulation model specifically includes:
s201, calculating the instantaneous winding loss of the series reactor at a preset initial temperature according to the loss model of the series reactor;
s202, calculating the highest temperature inside the series reactor according to the instantaneous loss of the winding and boundary parameters of a preset temperature field heat dissipation model and a preset fluid heat dissipation model;
s203, comparing whether the highest temperature obtained by the current simulation and the highest temperature obtained by the previous simulation meet the convergence error; if so, taking the highest temperature obtained by current simulation as the aging test temperature of the test sample; if not, returning to the step S201, and setting the preset initial temperature as the highest temperature obtained by the current simulation for recalculation.
Preferably, the test sample for obtaining the high-voltage reactor insulating medium specifically comprises five steps of sample preparation, sample primary screening, sample polishing, sample gold spraying and test sample selection.
Preferably, the sample preliminary screening adopts a 5-point positioning method to obtain a preliminary screening test sample with uniform thickness.
Preferably, the selection of the test sample is carried out by measuring the dielectric properties of the sample after the steps of sample preparation, sample preliminary screening, sample polishing and sample gold spraying are carried out under the constant temperature condition, and a plurality of samples with poor dielectric property precision and meeting a performance threshold are screened out as the final test sample.
Preferably, the step of establishing the aging test circuit of the test sample specifically comprises:
placing a plurality of test samples into a constant-temperature aging test box; the constant-temperature aging test box comprises a box body and a test unit, wherein the test unit consists of a plurality of copper electrodes and an aluminum plate electrode, the test sample is arranged between the copper electrodes and the aluminum plate electrode, and the test unit is arranged in the box body;
and connecting a third harmonic power supply and a power frequency power supply generator in parallel and then connecting a step-up transformer in series, and connecting a high-voltage side voltage output end of the step-up transformer in series to the copper electrode and the aluminum plate electrode, wherein the electrodes are arranged on the copper electrode and the aluminum plate electrode.
Preferably, the aging environment is constructed based on the aging test temperature and the aging test circuit, the test sample is placed in the aging environment for aging, and the acquiring of the dielectric property data of the aged test sample specifically comprises:
setting the environmental temperature of the constant-temperature aging test box as the aging temperature, setting the test voltage of the aging test circuit, and starting artificial aging; the test voltage is obtained by connecting a third harmonic power supply and a power frequency power supply generator in parallel and then connecting a step-up transformer in series;
and taking out an aging test sample from the constant-temperature aging test box at preset time intervals, numbering according to the aging time, and detecting the dielectric property of the aging test sample to obtain the dielectric property data of the aging test sample under different aging times.
Preferably, the establishing a test sample aging life evaluation model based on the dielectric characteristic data, and the evaluating the life of the insulating medium of the high-voltage reactor according to the test sample aging life evaluation model specifically includes:
fitting the dielectric characteristic data based on a double relaxation Cole-Cole model equation to obtain an aging characteristic parameter of the aging test sample in the aging process;
and establishing a test sample aging life evaluation model according to the aging characteristic parameters and the aging time, and evaluating the service life of the insulating medium of the high-voltage reactor by using the test sample aging life evaluation model.
Preferably, the fitting of the dielectric property data based on the double relaxation Cole-Cole model equation to obtain the aging characteristic parameters of the aging test sample in the aging process is specifically as follows:
establishing a complex dielectric constant expression of the epoxy resin dielectric based on a Debye equation:
determining the epoxy resin dielectric polarizability based on the complex dielectric constant expression of the epoxy resin dielectric as follows:
χ * (ω)＝ε * (ω)-ε hf
let epsilon s -ε hf ＝χ s Establishing a double relaxation Cole-Cole model equation about the epoxy resin:
separating the real part and the imaginary part of the complex polarizability based on a complex transform:
wherein, the first and the second end of the pipe are connected with each other,
in the above formula: epsilon * (ω) is the complex dielectric constant; epsilon hf Is a high frequency dielectric constant; epsilon s Is the static dielectric constant; τ is the relaxation polarization time constant; omega is angular frequency; j is an imaginary symbol; chi-type food processing machine * (ω) is the polarizability; chi shape s Is static dielectric polarizability; χ' (ω) is the real part of the polarizability; χ "(ω) is the imaginary part of the polarizability; n is a parameter of relaxation time distribution, and n is more than or equal to 0 and less than or equal to 1; epsilon 0 Is a vacuum dielectric constant; chi shape sα The relaxation strength being the relaxation process α; chi shape sβ Relaxation strength as relaxation process β; tau is α A relaxation time constant of the relaxation process α; tau. β Relaxation for relaxation process betaAn inter constant; n is α A distribution parameter being the relaxation process α; n is β A distribution parameter being the relaxation process β; sigma dc The direct current conductivity of the oil immersed bushing;
the aging characteristic parameters include: high frequency dielectric constant ε hf The relaxation strength χ of the alpha relaxation process sα Beta relaxation process relaxation strength χ sβ Alpha relaxation time constant tau of the relaxation process α Beta relaxation time constant tau of the relaxation process β Alpha relaxation process distribution parameter n α Distribution parameter n of beta relaxation process β 。
Preferably, the establishing of the test sample aging life evaluation model according to the aging characteristic parameter and the aging time specifically comprises:
and respectively fitting the aging characteristic parameters and the corresponding aging time of the plurality of test samples by adopting a least square method, and selecting a function model meeting the fitting precision as an epoxy resin aging life evaluation model:
wherein, Y t For aging time, τ α A, B and C are both constant parameters, which are the relaxation time constants of the alpha relaxation process.
According to the technical scheme, the invention has the following advantages:
according to the aging life evaluation method of the high-voltage reactor insulating medium, the aging test circuit of the test sample is established by determining the aging test temperature of the test sample, the test sample is aged, then the aged test sample is subjected to dielectric spectrum analysis to obtain the dielectric characteristic data of the aged test sample, a test sample aging life evaluation model is established according to the dielectric characteristic data, finally, the life of the high-voltage reactor insulating medium is evaluated according to the test sample aging life evaluation model, and the aging life of the high-voltage reactor insulating medium can be accurately evaluated.
The method and the device analyze the relation between the aging state of the test sample and the related physical quantity in the aging process of the test sample through the test method, establish the aging life evaluation model of the test sample, solve the technical problem that the aging state of the insulating medium in the high-voltage reactor is evaluated by adopting an empirical formula in the prior art, and the aging life of the insulating medium cannot be accurately obtained, and provide a basis for accurately evaluating the overall operation state of the high-voltage equipment.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the description below are only some embodiments of the present invention, and it is also possible for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
Fig. 1 is a flowchart of a method for evaluating an aging life of an insulating medium of a high-voltage reactor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a plate-plate electrode structure provided in an embodiment of the present invention;
FIG. 3 is a schematic diagram of a sinusoidal voltage test power supply provided by an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a burn-in test chamber according to an embodiment of the present invention;
FIG. 5 is a graph of a fit between the aging time and the relaxation time constant provided by an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides an aging life evaluation method for an insulating medium of a high-voltage reactor, relates to the technical field of aging life detection of solid dielectric media, and is used for solving the technical problem that the aging life of epoxy resin cannot be accurately obtained by evaluating the aging state of the epoxy resin in the high-voltage reactor by adopting an empirical formula in the prior art.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments of the present invention, belong to the protection scope of the present invention.
Due to the characteristics of high insulation, high sealing performance and durability of the epoxy resin, the epoxy resin is widely applied to insulation and packaging of high-voltage and low-voltage electric appliances, motors and electronic components, is most common in the insulation system of the current high-voltage electric reactor, but the epoxy resin is easily subjected to photo-oxidation and thermal aging under the influence of factors such as high heat, electric field, ultraviolet rays and the like, so that the aging state of the epoxy resin needs to be regularly evaluated to ensure the stable operation of the high-voltage electric controller. At present, the state of epoxy resin is completely evaluated by substation operators by means of experience or empirical formulas of maintainers, and the aging life of the epoxy resin cannot be accurately obtained. Therefore, in order to accurately obtain the aging life of the epoxy resin in the high-voltage reactor, the internal performance of the epoxy resin material needs to be analyzed through tests, and a relation between the relevant physical quantity in the epoxy resin aging process and the aging life needs to be established.
In view of the above, the present invention provides a method for evaluating an aging life of an insulating medium of a high-voltage reactor, and particularly relates to evaluating an aging life of an epoxy resin inside the high-voltage reactor. Referring to fig. 1, fig. 1 is a flowchart of a method for evaluating an aging life of an insulating medium of a high-voltage reactor according to an embodiment of the present invention.
The invention provides a method for evaluating the aging life of an insulating medium of a high-voltage reactor, which comprises the following steps:
100. and obtaining a test sample of the high-voltage reactor insulating medium.
For high-voltage electrical appliances, the appearance of epoxy cast insulators not only can improve the dielectric property, the mechanical strength and the like of the high-voltage electrical appliances, but also can reduce the volume, the mass and the like of electronic devices. When the epoxy cast insulator is produced, the flowability, the casting temperature, the gelation speed, the curing speed and the like of an epoxy resin manufacturing process need to be ensured, and the cured epoxy resin dielectric medium does not have the defects of looseness, impurities, bubbles or air holes, cracks and the like which reduce the electrical and mechanical properties, so that the obtained epoxy resin dielectric medium has good insulation property and long service life.
In order to ensure the validity of the test result, it is necessary to perform the test by using a consistent sample, and the embodiment obtains a high-quality and consistent epoxy resin sample by the following steps:
sample preparation: the main preparation raw material of the epoxy resin sample selected by the embodiment is preferably bisphenol A epoxy resin, and the epoxy resin sample is prepared in a stable environment with the constant temperature of 25 ℃ and the humidity of 60%, and the prepared sample has the characteristics of good hardness, high transparency, few bubbles, high glass transition temperature, basically no deformation in the environment of 150-200 ℃ and the like. Preferably, this example uses an epoxy resin sheet having a thickness of 1mm and a diameter of 50mm as a test sample.
Preliminary screening of samples: although the epoxy resin sample is subjected to vacuum treatment in the manufacturing process to remove a large amount of bubbles, the tiny bubbles are still difficult to discharge, and the breakdown field strength of the bubbles is far lower than that of a solid, so that when partial discharge exists in the bubbles in the epoxy resin, the service life of the epoxy resin is influenced. In order to improve the reliability and reproducibility of the sample, it is necessary to select a sample or a sample portion having no bubbles, pores, cracks, impurities, and the like inside. In addition, in order to ensure that the screened samples are flat, smooth and uniform in thickness, the embodiment adopts a method of 5-point positioning and averaging to ensure that the thicknesses of the obtained epoxy resin samples are all in the range of 1.00-1.05mm, and preferably, the embodiment selects circular epoxy resin samples with the diameter of 30 mm.
Grinding a sample: slight thickness unevenness of the sample causes a large difference in measurement of the dielectric spectrum (dielectric constant spectrum) of the sample, and poor reproducibility among samples. In order to overcome the error caused by the uneven thickness in the test, the embodiment further polishes the sample, and the thickness difference of the polished epoxy resin sample is controlled to be +/-0.01 mm.
Spraying gold on the sample: the uniformity of the electric field has a great influence on the insulating property of the solid medium. If an excessively strong electric field exists inside a certain portion of the sample, even if the insulating material has sufficient thickness and insulation margin, insulation breakdown failure may occur due to power plant unevenness after a period of putting into use. In order to improve the reliability and repeatability of the sample and optimize the electric field distribution in the sample, the embodiment performs the gold spraying treatment on the polished sample, preferably, in the embodiment, the upper surface of the sample is subjected to the gold spraying treatment with the diameter of 20mm, the lower surface of the sample is subjected to the gold spraying treatment with the diameter of 30mm, and the electric field passing through the sample can be uniformly distributed due to the fact that the metal film is arranged outside the epoxy resin sample after the gold spraying.
And (3) screening samples: the series of processing steps performed on the sample just ensure the consistency of the external characteristics of the sample, and since the dielectric spectrum characteristics of the solid medium have a large relationship with the medium and the temperature, the dielectric spectrum curve of the solid medium changes along with the change of the temperature. Therefore, in the present embodiment, the dielectric properties of the treated sample are further measured at a constant temperature, and a sample having a dielectric property accuracy difference of ± 1% is selected as a final test sample.
200. And determining the aging test temperature of the test sample according to the simulation model.
The epoxy resin insulation of the high-voltage reactor is influenced by factors such as high heat, an electric field and ultraviolet rays, and the three factors jointly promote the occurrence of medium aging. The thermal aging is an important form of deterioration and failure of the epoxy resin, and the high temperature causes the epoxy resin macromolecular chains to be broken and to be subjected to oxidative decomposition, so that more polar micromolecules are generated, and the relaxation polarization loss is increased. Meanwhile, epoxy resin aged for a long time in a high-temperature environment generates new defects due to the expansion of air gaps inside the epoxy resin caused by heating, and the defects are continuously enlarged under the action of an accumulation effect to finally generate faults.
To analyze the relationship between the aging state of the epoxy resin and the relevant physical quantity in the aging process, the dielectric property of the epoxy resin is firstly tested and changed under the action of temperature factors, namely, the epoxy resin sample is required to be aged under the condition of controllable and measurable temperature. The temperature should reach the requirement of the epoxy resin sample for continuous and stable aging, therefore, the temperature for the epoxy resin sample for continuous and stable aging needs to be determined first. Since there is a risk that the internal temperature of the high-voltage reactor is measured when the high-voltage reactor is put into use and reaches a saturation state, the present embodiment monitors the internal temperature of the high-voltage reactor when the high-voltage reactor is put into use and reaches the saturation state by using simulation.
300. And establishing an aging test circuit of the test sample.
The electric field is another important cause of the deterioration failure of the epoxy resin, and under the continuous action of the electric field, electrical aging occurs inside the epoxy resin, and some defects generated by thermal aging increase the probability of partial discharge. Therefore, the relationship between the aging state of the epoxy resin and the relevant physical quantity in the aging process is analyzed, and the dielectric property change of the epoxy resin under the action of an electric field factor is also tested, namely, the epoxy resin sample is required to be aged under the condition that the electric field is controllable and measurable.
The aging of the epoxy resin can be caused by strong ultraviolet rays, but the factor is weaker, and the embodiment analyzes the relationship between the aging state of the epoxy resin and relevant physical quantity in the aging process of the epoxy resin mainly by testing the dielectric properties of the epoxy resin under the two factors of electricity and heat.
400. And constructing an aging environment based on the aging test temperature and the aging test circuit, placing the test sample in the aging environment for aging, and acquiring dielectric property data of the aged test sample.
It can be understood that, under the combined action of electricity and heat, the internal molecular structure of the epoxy resin changes, and further, the dielectric properties of the aged epoxy resin also change, and for epoxy resins with different aging degrees, the dielectric properties of the epoxy resins with different aging degrees can be measured through dielectric spectrum analysis (dielectric constant spectrum analysis), so as to obtain the dielectric property data of the epoxy resins with different aging degrees.
500. And establishing a test sample aging life evaluation model based on the dielectric characteristic data, and evaluating the service life of the insulating medium of the high-voltage reactor according to the test sample aging life evaluation model.
It can be understood that, under a desired aging environment, the longer the aging time of the epoxy resin is, that is, the higher the aging degree is, the epoxy resin can be aged by controlling different times, so as to obtain epoxy resins with different aging degrees, and based on the knowledge obtained in the foregoing step 400, the dielectric characteristics of the epoxy resins with different aging degrees can be measured through dielectric spectrum analysis (dielectric constant spectrum analysis), so as to obtain dielectric characteristic data of the epoxy resins with different aging degrees. Different aging times (aging levels) correspond to different dielectric property data. Thus, the degree of aging of the epoxy resin can be evaluated by establishing a functional relationship between the dielectric property data and the aging time.
According to the aging life evaluation method of the high-voltage reactor insulating medium, an epoxy resin test sample meeting test precision and test requirements is obtained through pretreatment, the aging test temperature of the epoxy resin test sample is determined through a sub-simulation mode, an aging test circuit of the epoxy resin test sample is established to age the epoxy resin test sample, then dielectric spectrum analysis is carried out on the aged epoxy resin test sample to obtain dielectric characteristic data of the aged epoxy resin test sample, an aging life evaluation model of the epoxy resin test sample is established according to the dielectric characteristic data, and accurate evaluation of the aging life of the high-voltage reactor insulating medium (epoxy resin) can be achieved.
The method and the device analyze the relation between the aging state of the epoxy resin test sample and the related physical quantity in the aging process of the epoxy resin test sample through a test method, establish an aging life evaluation model of the epoxy resin test sample, solve the technical problem that the aging state of an insulating medium (epoxy resin) in a high-voltage reactor is evaluated by adopting an empirical formula in the prior art, and the aging life of the insulating medium (epoxy resin) cannot be accurately obtained, and provide a basis for accurately evaluating the overall operation state of high-voltage equipment.
On the basis of the foregoing embodiment, the present application provides another preferred embodiment, and step 200 may specifically be implemented by:
when the high-voltage reactor is put into use and reaches a saturation state, the internal iron core generates heat, the overall temperature of the reactor can be increased due to the increase of the temperature of the iron core, the temperature of the epoxy resin medium is further increased, and the epoxy resin medium is aged due to the high temperature. Therefore, it is necessary to obtain the internal stable temperature of the high-voltage reactor when the high-voltage reactor is put into use and reaches a saturation state, and the epoxy resin sample is subjected to an aging test at the stable temperature.
Because the high-voltage reactor is dangerous when being put into use and reaching the saturation state for internal temperature measurement, the embodiment monitors the internal temperature of the high-voltage reactor when being put into use and reaching the saturation state by adopting simulation, preferably, the embodiment establishes a series reactor loss model by using finite element electromagnetic software to realize the operation simulation of the high-voltage reactor, and the method specifically comprises the following steps:
s201, establishing a loss model of the series reactor, and calculating the instantaneous winding loss of the series reactor at a preset initial temperature according to the loss model of the series reactor.
A loss model of the series reactor is established by using finite element electromagnetic software, eddy current heating of the winding is neglected, the winding is simplified, and a transient solver is selected for solving.
Setting reactor winding materials in a loss model of the series reactor, exciting current applied to a winding, and carrying out simulation calculation on the winding loss of the series reactor at the initial temperature; wherein. The resistance of the winding material is a function of temperature: r ═ f (t), r is winding resistance, and t is winding temperature/winding initial temperature; the formula for calculating the winding loss is as follows: p 0 ＝f(R 0 )，R 0 Is the winding resistance (same as r), P 0 Instantaneous loss of the winding at the temperature; preferably, in this embodiment, the current is excitedIncluding a 50Hz fundamental component and a 150Hz harmonic component.
S202, establishing a temperature field heat dissipation model and a fluid heat dissipation model, and calculating the highest temperature inside the series reactor according to the instantaneous loss of the winding and the boundary parameters of the preset temperature field heat dissipation model and the preset fluid heat dissipation model.
And (2) transmitting the instantaneous loss of the winding obtained through the electromagnetic software simulation in the step (S201) to the temperature field heat dissipation model and the fluid heat dissipation model, setting functions of boundary condition parameters such as heat conduction, air convection heat dissipation and the like related to the temperature in the temperature field heat dissipation model and the fluid heat dissipation model, simulating the whole temperature of the series reactor, and obtaining the highest temperature in the reactor.
S203, comparing whether the highest temperature obtained by the current simulation and the highest temperature obtained by the previous simulation meet the convergence error; if so, taking the highest temperature obtained by the current simulation as the aging test temperature of the test sample; if not, returning to the step S201, and setting the preset initial temperature as the highest temperature obtained by the current simulation for recalculation.
It can be understood that, the steps S201 to S203 are iterative processes, and whether iteration is converged is determined by determining a difference error between the highest temperature obtained by current iteration simulation and the highest temperature obtained by previous iteration simulation; preferably, in this embodiment, if the highest temperature obtained by the current iterative simulation is consistent with the highest temperature obtained by the previous iterative simulation, the highest temperature obtained by the current iterative simulation is used as the epoxy resin aging test temperature; if not, transmitting the highest temperature obtained by the current iteration to the electromagnetic software, setting the highest temperature obtained by the current iteration as a boundary condition parameter of the fluid software, returning to the step S201 for recalculation until the highest temperature obtained by the current iteration simulation is consistent with the highest temperature obtained by the previous iteration simulation.
In this embodiment, through adopting the mode of emulation analysis to acquire ageing tests temperature, can set test temperature to the temperature that can make the epoxy sample directly produce ageing, avoided the problem that the answer temperature is crossed high excessively or is crossed ageing poor effect excessively.
On the basis of the foregoing embodiment, the present application provides another preferred embodiment, and step 300 may specifically be implemented by:
as can be seen from the structure of the high-voltage reactor, the electric field applied to the epoxy resin is formed by a curved surface between the windings, and therefore the electric field of the epoxy resin is equivalent to a plate-to-plate electric field. In order to simulate the electric field that the epoxy resin bears under the actual operation condition, in this embodiment, electrodes are disposed at two ends of the epoxy resin sample obtained in step 100, so as to obtain an epoxy resin test electrode capable of generating a plate-plate electric field, as shown in fig. 2, and fig. 2 is a schematic diagram of a plate-plate electrode structure provided by an embodiment of the present invention.
Preferably, the epoxy resin is placed in a constant-temperature aging test box; wherein the constant temperature aging test chamber comprises a chamber body and a test unit, the test unit is composed of a plurality of copper electrodes and an aluminum plate electrode, the epoxy resin is arranged between the copper electrodes and the aluminum plate electrode, the test unit is arranged in the chamber body (see figure 4)
In view of the fact that the actual voltage waveform of the series reactor is basically 50Hz and a small amount of 150Hz third harmonic waveform, in order to simulate the actual voltage, the third harmonic power supply and the power frequency power supply generator are connected in parallel and then connected in series with the step-up transformer, so that the high-voltage output of the secondary side of the step-up transformer is loaded on the epoxy resin, and the epoxy is specifically arranged between the copper electrode and the aluminum plate electrode, so that the high-voltage output of the secondary side of the step-up transformer is specifically loaded on the copper electrode and the aluminum plate electrode.
Preferably, in the present embodiment, the test voltage is:
in the above formula, n is the number of turns of the single encapsulated winding, U test Fig. 3 is a schematic diagram of a sinusoidal voltage test power supply provided in this embodiment for testing voltage.
Preferably, the present application provides another preferred embodiment illustrating the setting of the thermal aging test environment.
On the basis of the foregoing embodiment, the present application provides another preferred embodiment, and the step 400 can be specifically implemented by:
after the epoxy resins are placed in the constant-temperature aging test chamber, the silicone oil is used for immersing the sample to isolate air, the environmental temperature of the constant-temperature aging test chamber is set to the aging temperature obtained in the step 200, and meanwhile, the test voltage is set to start artificial aging. And taking out an aging test sample from the aging test box at preset time intervals, numbering according to the aging time, and detecting the dielectric property of the aging test sample by using dielectric spectrum analysis to obtain the dielectric property data of the aging test sample under different aging times.
Preferably, in this embodiment, the aging test chamber includes (copper) electrode, aluminum plate electrode (earth electrode) and box, and the epoxy test sample sets up between (copper) electrode and aluminum plate electrode (earth electrode), and the high-voltage terminal electrode is the copper post of diameter 30mm, and the earth electrode uses 400mm 200mm 10 mm's aluminum plate, and the bottom surface and the aluminum plate of copper post constitute board-board electrode, and the copper electrode evenly distributed is on aluminum plate, and every electrode top screw all can be connected with high voltage power supply. The device can provide an electrothermal aging test platform for 8 epoxy resin samples simultaneously. In order to prevent the epoxy resin sheet from flashover along the surface, silicon oil is filled in the device to isolate air during aging, and the influence of air oxidation on the electrothermal aging of the epoxy resin is eliminated. The device simple structure is reliable, and convenient operation can improve the efficiency and the precision of ageing state aassessment, and constant temperature ageing test case refers to figure 4.
On the basis of the foregoing embodiment, there is provided another preferred embodiment, and the step 500 can be specifically realized by:
it is understood that the electrothermal-coupled aging life of the epoxy resin can be evaluated by analyzing the relationship between the aging state of the epoxy resin and the relevant physical quantity during the aging process thereof.
The embodiment is based on a double relaxation Cole-Cole model empirical formula, and the complex dielectric constant epsilon of the test sample is separated through complex number transformation * As a function of the real and imaginary parts of the characteristic parameter, for the real and imaginary parts of the complex permittivityFitting the imaginary part data to obtain characteristic parameters, comparing and analyzing the relation between the characteristic parameters and different aging times under different aging degrees based on an empirical formula to obtain an aging evaluation model of the epoxy resin, and evaluating the aging life of the epoxy resin according to the aging model of the epoxy resin.
Specifically, the method comprises the following steps:
according to the basic theory of dielectric spectrum (dielectric constant spectrum), a Debye equation is introduced to obtain a complex dielectric constant expression of the epoxy resin dielectric:
the epoxy resin dielectric polarizability obtained based on the complex dielectric constant expression of the epoxy resin dielectric is as follows:
χ * (ω)＝ε * (ω)-ε hf (2)
let epsilon s -ε hf ＝χ s Introducing a parameter n to obtain a Cole-Cole model:
acquiring an imaginary part of the complex dielectric constant of the epoxy resin, and determining that a peak point appears on the imaginary part in a high-frequency band; considering the direct current conductivity σ of epoxy resin dc The double relaxation Cole-Cole model equation for epoxy resins is established as follows:
wherein: epsilon hf Is a high frequency dielectric constant; epsilon s Is the static dielectric constant; τ is the relaxation polarization time constant; omega is angular frequency; j is an imaginary symbol; chi shape * (ω) is the polarizability; chi-type food processing machine s Is static dielectric polarizability; χ' (ω) is the real part of the polarizability, and χ "(ω) is the imaginary part of the polarizability; n is a parameter of relaxation time distribution, and n is more than or equal to 0 and less than or equal to 1;ε 0 in order to have a vacuum dielectric constant, preferably,. epsilon.in the present embodiment 0 ＝8.85×10 -12 F/m；χ sα The relaxation strength being the relaxation process α; chi shape sβ Relaxation strength as relaxation process β; tau is α The relaxation time constant, τ, of the relaxation process α β A relaxation time constant of β, and, τ α >τ β ；n α A distribution parameter being the relaxation process α; n is β A distribution parameter being the relaxation process β; sigma dc The direct current conductivity of the oil-immersed bushing is adopted.
Separating the real part and the imaginary part of the complex polarization rate by the complex transformation of the formula (4), as follows:
wherein S, Q, R in the above formula (5) is determined by the following formula
Fitting the real part and the imaginary part of the complex dielectric constant of the epoxy resin respectively by applying the formula (6) can obtain 8 representative characteristic parameters: i.e., high frequency dielectric constant ∈ hf The relaxation strength χ of the alpha relaxation process sα Beta relaxation process relaxation strength χ sβ Alpha relaxation time constant tau of the relaxation process α Beta relaxation time constant tau of the relaxation process β Alpha relaxation process distribution parameter n α Beta relaxation process distribution parameter n β 。
Wherein S is α 、Q α 、R α Intermediate parameters determined by the alpha relaxation process; s β 、Q β 、R β Is an intermediate parameter determined by the beta relaxation process; n is relaxation timeN is more than or equal to 0 and less than or equal to 1.
It can be understood that, along with the continuous accumulation of the internal aging products of epoxy resin, the process of epoxy resin relaxation polarization can accelerate, preferably, this embodiment adopts the least square method to respectively fit the aging characteristic parameter of the real number test sample of epoxy of a plurality of different ageing degree and the aging time that corresponds, selects the function model that satisfies the preset fitting precision as the ageing life assessment model of epoxy resin, obtains through fitting analysis: the fitting precision is satisfied between the aging time and the relaxation time constant, the image is fitted, see fig. 5, and the following epoxy resin aging evaluation model is obtained through fitting:
wherein, Y t For aging time, τ α A relaxation time constant of the relaxation component α; A. b and C are both normal parameters.
And (3) acquiring the dielectric spectrum of the epoxy resin according to the formulas (1) to (7) to acquire the relaxation time constant characteristic parameter of the dielectric spectrum of the epoxy resin, and then accurately acquiring the aging life of the epoxy resin according to the epoxy resin aging evaluation model of the formula (8).
According to the aging life evaluation method of the high-voltage reactor insulating medium, aiming at the characteristic that the high-voltage reactor epoxy resin main insulation bears high-temperature and high-voltage working environment for a long time, the aging temperature of the epoxy resin is accurately obtained through simulation, and dielectric spectrum characteristic parameters of a plurality of groups of epoxy resin samples in different aging states are measured under the condition of electricity and heat combined aging factors. On the basis, based on a double-relaxation Co l e-Co l e model empirical formula, a common least square method is adopted to perform curve fitting on test data to establish an epoxy resin aging life evaluation model, the technical problem that the aging state of epoxy resin in a high-voltage reactor is evaluated by adopting the empirical formula in the prior art, and the aging life of the epoxy resin cannot be accurately obtained is solved, and a basis is provided for accurately evaluating the overall operation state of high-voltage equipment.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for evaluating the aging life of an insulating medium of a high-voltage reactor is characterized by comprising the following steps:
obtaining a test sample of the high-voltage reactor insulating medium;
determining the aging test temperature of the test sample according to the simulation model;
establishing an aging test circuit of the test sample;
establishing an aging environment based on the aging test temperature and the aging test circuit, placing the test sample in the aging environment for aging, and obtaining dielectric property data of the aged test sample;
and establishing a test sample aging life evaluation model based on the dielectric characteristic data, and evaluating the service life of the insulating medium of the high-voltage reactor according to the test sample aging life evaluation model.
2. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 1, wherein the simulation model comprises a series reactor loss model, a temperature field heat dissipation model and a fluid heat dissipation model, and the determining the aging test temperature of the test sample according to the simulation model specifically comprises:
s201, calculating the instantaneous winding loss of the series reactor at a preset initial temperature according to the loss model of the series reactor;
s202, calculating the highest temperature inside the series reactor according to the instantaneous loss of the winding and boundary parameters of a preset temperature field heat dissipation model and a preset fluid heat dissipation model;
s203, comparing whether the highest temperature obtained by the current simulation and the highest temperature obtained by the previous simulation meet the convergence error; if so, taking the highest temperature obtained by the current simulation as the aging test temperature of the test sample; if not, returning to the step S201, and setting the preset initial temperature as the highest temperature obtained by the current simulation for recalculation.
3. The method for evaluating the aging life of the high-voltage reactor insulation medium according to claim 1, wherein the step of obtaining the test sample of the high-voltage reactor insulation medium specifically comprises five steps of sample preparation, sample preliminary screening, sample grinding, sample gold spraying and test sample selection.
4. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 3, wherein the sample prescreening adopts a 5-point positioning method to obtain prescreening test samples with uniform thickness.
5. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 4, wherein the test sample is selected by measuring the dielectric properties of the sample after the steps of sample preparation, sample preliminary screening, sample polishing and sample gold spraying are carried out under a constant temperature condition, and a plurality of samples with poor dielectric property precision and meeting a performance threshold value are selected as final test samples.
6. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 5, wherein the aging test circuit for establishing the test sample is specifically:
placing a plurality of test samples into a constant-temperature aging test box; the constant-temperature aging test box comprises a box body and a test unit, wherein the test unit consists of a plurality of copper electrodes and an aluminum plate electrode, the test sample is arranged between the copper electrodes and the aluminum plate electrode, and the test unit is arranged in the box body;
and connecting a third harmonic power supply and a power frequency power supply generator in parallel and then connecting a step-up transformer in series, and connecting a high-voltage side voltage output end of the step-up transformer in series to the copper electrode and the aluminum plate electrode to construct the aging test circuit.
7. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 6, wherein the aging environment is constructed based on the aging test temperature and the aging test circuit, the test sample is placed in the aging environment for aging, and the data of the dielectric properties of the aged test sample are specifically acquired as follows:
setting the environmental temperature of the constant-temperature aging test box as the aging temperature, setting the test voltage of the aging test circuit, and starting artificial aging; the test voltage is obtained by connecting a third harmonic power supply and a power frequency power supply generator in parallel and then connecting a step-up transformer in series;
and taking out an aging test sample from the constant-temperature aging test box at preset time intervals, numbering according to the aging time, and carrying out dielectric property detection on the aging test sample to obtain dielectric property data of the aging test sample under different aging times.
8. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 7, wherein the establishing a test sample aging life evaluation model based on the dielectric characteristic data and evaluating the life of the insulating medium of the high-voltage reactor according to the test sample aging life evaluation model specifically comprises the following steps:
fitting the dielectric characteristic data based on a double relaxation Cole-Cole model equation to obtain an aging characteristic parameter of the aging test sample in the aging process;
and establishing a test sample aging life evaluation model according to the aging characteristic parameters and the aging time, and evaluating the service life of the insulating medium of the high-voltage reactor by using the test sample aging life evaluation model.
9. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 8, wherein the dielectric characteristic data are fitted based on a double relaxation Cole-Cole model equation, and the aging characteristic parameters of the aging test sample in the aging process are specifically:
establishing a complex dielectric constant expression of the epoxy resin dielectric based on the Debye equation:
determining the epoxy resin dielectric polarizability based on the complex dielectric constant expression of the epoxy resin dielectric as follows:
χ * (ω)＝ε * (ω)-ε hf
let epsilon s -ε hf ＝χ s Establishing a double relaxation Cole-Cole model equation about the epoxy resin:
separating the real part and the imaginary part of the complex polarizability based on a complex transform:
wherein the content of the first and second substances,
in the above formula: epsilon * (ω) is the complex dielectric constant; epsilon hf Is a high frequency dielectric constant; epsilon s Is the static dielectric constant; tau is a relaxation polarization time constant; omega is angular frequency; j is an imaginary symbol; chi shape * (ω) is the polarizability; chi-type food processing machine s Is static dielectric polarizability; χ' (ω) is the real part of the polarizability; χ "(ω) is the imaginary part of the polarizability; n is a parameter of relaxation time distribution, and n is more than or equal to 0 and less than or equal to 1; epsilon 0 Is a vacuum dielectric constant; chi shape sα The relaxation strength being the relaxation process α; chi shape sβ A relaxation strength which is a relaxation process β; tau is α A relaxation time constant of the relaxation process α; tau. β A relaxation time constant which is the relaxation process β; n is α A distribution parameter being the relaxation process α; n is β A distribution parameter being the relaxation process β; sigma dc The direct current conductivity of the oil immersed bushing;
the aging characteristic parameters include: high frequency dielectric constant ε hf The relaxation strength of the alpha relaxation process χ sα Beta relaxation process relaxation strength χ sβ Alpha relaxation time constant tau of the relaxation process α Beta relaxation time constant tau of the relaxation process β Alpha relaxation process distribution parameter n α Distribution parameter n of beta relaxation process β 。
10. The method for evaluating the aging life of the insulating medium of the high-voltage reactor according to claim 9, wherein the establishing of the test sample aging life evaluation model according to the aging characteristic parameter and the aging time specifically comprises:
and respectively fitting the aging characteristic parameters and the corresponding aging time of the plurality of test samples by adopting a least square method, and selecting a function model meeting the fitting precision as an epoxy resin aging life evaluation model:
wherein, Y t For aging time, τ α A, B and C are both constant parameters, which are the relaxation time constants of the alpha relaxation process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210821418.3A CN115128385A (en) | 2022-07-13 | 2022-07-13 | Aging life evaluation method for insulating medium of high-voltage reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210821418.3A CN115128385A (en) | 2022-07-13 | 2022-07-13 | Aging life evaluation method for insulating medium of high-voltage reactor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115128385A true CN115128385A (en) | 2022-09-30 |
Family
ID=83383938
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210821418.3A Pending CN115128385A (en) | 2022-07-13 | 2022-07-13 | Aging life evaluation method for insulating medium of high-voltage reactor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115128385A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117783758A (en) * | 2024-02-23 | 2024-03-29 | 国网智能电网研究院有限公司 | Device and method for measuring aging and pole-shell space electric field of power capacitor |
-
2022
- 2022-07-13 CN CN202210821418.3A patent/CN115128385A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117783758A (en) * | 2024-02-23 | 2024-03-29 | 国网智能电网研究院有限公司 | Device and method for measuring aging and pole-shell space electric field of power capacitor |
| CN117783758B (en) * | 2024-02-23 | 2024-05-10 | 国网智能电网研究院有限公司 | Device and method for measuring aging and pole-shell space electric field of power capacitor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Ekanayake et al. | Frequency response of oil impregnated pressboard and paper samples for estimating moisture in transformer insulation | |
| CN109696605B (en) | Method for evaluating service life of epoxy mica insulation of generator stator bar | |
| CN106053955B (en) | A kind of low frequency sinusoidal motivates the test method of lower Oil-Paper Insulation relative dielectric constant | |
| Reddy et al. | Effect of coldfog on the corona induced degradation of silicone rubber samples | |
| CN108089038A (en) | The experimental rig and method that analysis winding defect pyrogenicity influences paper oil insulation performance | |
| Yew et al. | Effects of moisture and temperature on the frequency domain spectroscopy analysis of power transformer insulation | |
| CN115128385A (en) | Aging life evaluation method for insulating medium of high-voltage reactor | |
| Aakre et al. | Partial discharge inception voltage of voids enclosed in epoxy/mica versus voltage frequency and temperature | |
| Chowdhury et al. | Temperature compensation of frequency domain spectroscopy measurement for condition assessment of oil-paper insulation | |
| Xu et al. | Extracting frequency spectroscopy of oil-immersed paper based on Havriliak–Negami model without known insulation structure of transformer | |
| Linde et al. | Comparison of Dielectric Loss Measuring Methods on Epoxy Samples under Harmonic Distorted Voltages | |
| Kumar et al. | Correlation between time and frequency domain measurements for the insulation diagnosis of current transformers | |
| Yuan et al. | Simulation analysis on FDS of power transformer by FEM approach | |
| Banaszczyk et al. | Dielectric strength measurements of silicone gel | |
| Ekanayake et al. | Diagnostic of power transformers in Sri Lanka application of dielectric spectroscopy in frequency domain | |
| Kiiza et al. | The effect of partial discharge by-products on the dielectric frequency response of oil-paper insulation comprising of a small cavity | |
| Shu et al. | Corona onset characteristics of contact box in switchgear with condensation under high humidity and pollution conditions | |
| Fedosov et al. | The influence of electrical equipment insulation aging degree on the growth rate of partial discharges power | |
| Kumar et al. | Importance of Depolarization Current in the Diagnosis of Oil-Paper Insulation of Power Transformer | |
| Yoon et al. | A Study of Relationship Between Vt and $\mathrm {Tan}\delta $ Characteristic on Epoxy Resin | |
| Shiling | Study on dielectric property test and image computer recognition of UHVDC bushing | |
| Yao et al. | Evaluation Method of Oil-paper Insulation Bushing Damp Type Based on Polarity Reversal | |
| Pan et al. | Research on the Influence of Temperature on the Frequency Domain Spectroscopy Characteristics of AC Oil-Paper Insulated Bushings | |
| Haering et al. | Evaluation of extruded hvdc cable systems | |
| Reddy et al. | Studies on corona degradation of polymeric insulators |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |