CN117805560A - Epoxy resin material electrical branch degradation experimental platform and experimental method - Google Patents
Epoxy resin material electrical branch degradation experimental platform and experimental method Download PDFInfo
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- CN117805560A CN117805560A CN202311845406.5A CN202311845406A CN117805560A CN 117805560 A CN117805560 A CN 117805560A CN 202311845406 A CN202311845406 A CN 202311845406A CN 117805560 A CN117805560 A CN 117805560A
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- 239000003822 epoxy resin Substances 0.000 title claims description 63
- 229920000647 polyepoxide Polymers 0.000 title claims description 63
- 230000015556 catabolic process Effects 0.000 title claims description 59
- 238000006731 degradation reaction Methods 0.000 title claims description 59
- 238000002474 experimental method Methods 0.000 title claims description 45
- 239000000463 material Substances 0.000 title claims description 43
- 238000000034 method Methods 0.000 claims abstract description 39
- 230000008569 process Effects 0.000 claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 230000005611 electricity Effects 0.000 claims abstract description 11
- 230000035882 stress Effects 0.000 claims description 73
- 230000009471 action Effects 0.000 claims description 22
- 238000012360 testing method Methods 0.000 claims description 21
- 230000008878 coupling Effects 0.000 claims description 20
- 238000010168 coupling process Methods 0.000 claims description 20
- 238000005859 coupling reaction Methods 0.000 claims description 20
- 230000001808 coupling effect Effects 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 16
- 239000004593 Epoxy Substances 0.000 claims description 13
- 210000001787 dendrite Anatomy 0.000 claims description 12
- 230000008646 thermal stress Effects 0.000 claims description 11
- 239000003921 oil Substances 0.000 claims description 10
- 235000019198 oils Nutrition 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 6
- 230000000903 blocking effect Effects 0.000 claims description 5
- 229920002545 silicone oil Polymers 0.000 claims description 5
- 235000015112 vegetable and seed oil Nutrition 0.000 claims description 5
- 239000008158 vegetable oil Substances 0.000 claims description 5
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 4
- 238000003756 stirring Methods 0.000 claims description 4
- 238000009849 vacuum degassing Methods 0.000 claims description 4
- 238000001291 vacuum drying Methods 0.000 claims description 4
- 230000008901 benefit Effects 0.000 description 7
- 238000009413 insulation Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
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Classifications
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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
-
- 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
- G01R31/1209—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 using acoustic measurements
-
- 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
- G01R31/1218—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 using optical methods; using charged particle, e.g. electron, beams or X-rays
-
- 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
- G01R31/20—Preparation of articles or specimens to facilitate testing
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
The experimental platform is provided with an experimental cavity for accommodating a discharge medium and a thermocouple arranged in the experimental cavity for measuring temperature data in real time, the heating platform is in heat conduction connection with the experimental cavity to heat the measured sample in the experimental cavity to a preset temperature, the measured sample flows from the high-voltage needle electrode through high-voltage electricity and discharges to the ground electrode to generate an electric branch, the CCD camera faces the measured sample to shoot image data of the electric branch growth process, and the partial discharge detector detects partial discharge signals in the discharge process of the measured sample.
Description
Technical Field
The invention relates to the technical field of electrical equipment detection, in particular to an experimental platform and an experimental method for electrical branch degradation of an epoxy resin material under the coupling effect of electricity, heat and a machine.
Background
With further improvement of the transmission voltage level and the transmission capacity of the power system, great challenges are presented to the reliability and stability of the power equipment. The gum dipping paper sleeve is one of main insulating forms of high-voltage power equipment, and plays an insulating role, and also needs to play a certain stress role in operation. The sleeve used in the converter station is a glue-dipped paper sleeve, wherein the epoxy resin insulating material is subjected to the phenomenon of insulation degradation under the combined action of electric stress, thermal stress and mechanical stress in the operation process, and the electric branch is taken as a typical degradation form of the valve side dry sleeve, so that the epoxy resin insulating material is widely paid attention to by students at home and abroad.
Conventional bushing insulation degradation tests are typically tests under a single electrical, thermal or mechanical stress, and it is difficult to comprehensively and accurately evaluate the degradation state of a test specimen. Particularly, in the actual operation of the electric power system, the epoxy resin sample is subjected to complex actions of electric stress, thermal stress and mechanical stress at the same time, so that an experimental platform capable of simulating a real working environment and comprehensively evaluating the degradation state of the epoxy resin valve side dry sleeve insulation degradation sample is needed.
In the prior art, although a test scheme for applying mechanical stress to a solid insulating material is provided, the research on an experimental platform of a brittle epoxy resin material under the combined action of an electric machine and a thermal machine is not enough. Therefore, it is necessary to provide an experimental platform capable of simulating a real working environment and comprehensively evaluating the degradation state of a sample.
The above information disclosed in the background section is only for enhancement of understanding of the background of the invention and therefore may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
In view of the above problems, the present invention aims to overcome the defects of the prior art, and provide an experimental platform and an experimental method for electrical branch degradation of an epoxy resin material under the action of electro-thermal-mechanical coupling. The deterioration state of the epoxy resin specimen can be detected by the combination of the electrical branch growth characteristics and the partial discharge.
The aim of the invention is achieved by the following technical scheme.
An experimental platform for the electrical branch degradation of epoxy resin material under the coupling action of an electric-thermal-mechanical machine comprises,
the sample to be tested comprises an epoxy resin sleeve sample, a high-voltage needle electrode inserted into the epoxy resin sleeve sample and a ground electrode arranged at the bottom of the epoxy resin sleeve sample, wherein the surface of the epoxy resin sleeve sample is provided with a strain gauge,
a mechanical stress applying device, which comprises a clamp for clamping two sides of a tested sample and a torque wrench for applying stress to the tested sample,
a strain gauge connected to the strain gauge for measuring mechanical stress data of the sample under test,
an experiment platform provided with an experiment cavity for accommodating discharge medium and a thermocouple arranged in the experiment cavity for measuring temperature data in real time,
a heating table which is connected with the experiment cavity in a heat conduction way so as to heat the tested sample in the experiment cavity to a preset temperature,
a DC voltage generator for providing a DC voltage, which is connected to the high voltage needle electrode via a protection resistor,
an alternating voltage source for providing alternating voltage and connected to the high voltage pin electrode through a blocking capacitor,
a voltage divider connected to the DC voltage generator and the AC voltage source via a protection resistor to divide the DC voltage and the AC voltage,
a harmonic source connected to the high-voltage needle electrode via a protection resistor to superimpose various types of voltage waveforms, a sample to be measured flowing in from the high-voltage needle electrode via high voltage electricity and discharging to the ground electrode to generate an electric branch,
a CCD camera facing the tested sample to shoot image data of the growth process of the electric branch,
a partial discharge instrument for detecting partial discharge signals in the discharge process of the sample to be detected,
and a processor connected to the strain gauge, thermocouple, CCD camera and partial discharge meter to collect and process the mechanical stress data, temperature data, image data and partial discharge signals.
The experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical device further comprises an oscilloscope for measuring voltage waveforms, and the processor is connected with the oscilloscope to correlate the voltage waveforms with the mechanical stress data, the temperature data, the image data and the local discharge signals.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the experimental platform is provided with a transmission light source for irradiating the experimental cavity, and the transmission light source is positioned at one side of the experimental cavity opposite to the CCD camera.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the electric stress is provided by an alternating voltage source, a direct voltage generator and a harmonic source, the thermal stress is provided for a tested sample by a heating platform below an experimental cavity in an oil bath heating mode, and the mechanical stress rotates a nut for clamping the sample through a torque wrench, so that the compressive stress borne by the tested sample is measured by a strain gauge to reach a required stress level.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the partial discharge instrument measures partial discharge signals in a combined mode of an ultrasonic detection method and a pulse current method, and the processor analyzes the partial discharge characteristics based on the partial discharge signals.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the heating platform is a constant-temperature heating platform.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the torque wrench applies a calculation formula of mechanical stress:
wherein F is the tightening force of the bolt on the tested sample, F t The tightening force applied to the single-sided bolt, M t The screw bolt tightening torque is sigma the stress applied to two sides of a measured sample, S is the cross-sectional area of a clamped plane of the measured sample, k is a dimensionless proportionality coefficient, according to the screw bolt model, the screw bolt tightening torque is referred to in the mechanical design handbook, and is 0.3, and d is the nut diameter of the torque wrench.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the tested sample is immersed in the discharge medium, and the discharge medium comprises transformer oil, silicone oil or insulating vegetable oil.
In the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the tested sample comprises an epoxy impregnated paper or an epoxy resin sleeve sample.
The experimental method of the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical comprises the following steps,
preparing a tested sample, pouring epoxy resin and a curing agent into a three-necked flask according to a mass ratio of 100:85, mixing to form a mixture, placing the mixture into a stirrer, stirring in vacuum, uniformly mixing, and removing air in the mixture;
placing crepe paper in a mould and presetting an electrode, controlling the distance between the tip of a high-voltage needle electrode and a ground electrode to be 2+/-0.2 mm, pouring the mixture into the mould of the preset electrode, and solidifying at constant temperature after vacuum degassing treatment in a vacuum drying oven to obtain a tested sample;
the method comprises the steps that a measured sample is clamped by a mechanical stress applying device and then immersed in a discharge medium in an experiment cavity, an alternating current voltage source, a direct current voltage generator and a harmonic wave provide electric stress, a heating table below the experiment cavity provides preset temperature for thermal stress, the mechanical stress is provided by a torque wrench, the measured sample flows in from a high-voltage needle electrode through high-voltage electricity and is discharged to a ground electrode to generate an electric branch, a CCD camera shoots image data of the electric branch in a growth process, a partial discharge meter detects partial discharge signals in the discharge process of the measured sample, a strain meter measures mechanical stress data of the measured sample, and a thermocouple measures temperature data of the measured sample in real time.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, through the electrical dendrite test and partial discharge detection under the combined action of the electric heat machine and the thermal heat machine on the epoxy resin sleeve sample, the test can be performed under the condition of simulating the formal working environment, and the method is closer to the actual operation condition of the sleeve, so that the degradation state index of the sleeve sample is more accurate.
The foregoing description is only an overview of the technical solutions of the present invention, to the extent that it can be implemented according to the content of the specification by those skilled in the art, and to make the above-mentioned and other objects, features and advantages of the present invention more obvious, the following description is given by way of example of the present invention.
Drawings
Various other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. It is evident that the figures described below are only some embodiments of the invention, from which other figures can be obtained without inventive effort for a person skilled in the art. Also, like reference numerals are used to designate like parts throughout the figures.
In the drawings:
FIG. 1 is a schematic structural diagram of an experimental platform for electrical dendrite degradation of an epoxy resin material under electro-thermo-mechanical coupling according to one embodiment of the present invention;
FIG. 2 is a schematic diagram of the structure of a sample to be tested of an electrical dendrite degradation experiment table of an epoxy resin material under the action of an electro-thermo-mechanical coupling according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of a mechanical stress applying clamp and a sample clamping manner of an electrical branch degradation experiment platform of an epoxy resin material under the action of an electro-thermal-mechanical coupling according to an embodiment of the invention;
fig. 4 is a schematic diagram of a strain gauge of an experimental platform for electrical dendrite degradation of epoxy materials under electro-thermo-mechanical coupling to measure stress applied to a sample under test according to one embodiment of the present invention.
The invention is further explained below with reference to the drawings and examples.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It should be noted that certain terms are used throughout the description and claims to refer to particular components. Those of skill in the art will understand that a person may refer to the same component by different names. The description and claims do not identify differences in terms of components, but rather differences in terms of the functionality of the components. As used throughout the specification and claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description hereinafter sets forth a preferred embodiment for practicing the invention, but is not intended to limit the scope of the invention, as the description proceeds with reference to the general principles of the description. The scope of the invention is defined by the appended claims.
For the purpose of facilitating an understanding of the embodiments of the present invention, reference will now be made to the drawings, by way of example, and specific examples of which are illustrated in the accompanying drawings.
For better understanding, as shown in fig. 1 to 4, an experimental platform for electrical dendrite degradation of an epoxy resin material under the effect of electro-thermo-mechanical coupling includes,
the sample to be tested comprises an epoxy resin sleeve sample, a high-voltage needle electrode inserted into the epoxy resin sleeve sample and a ground electrode arranged at the bottom of the epoxy resin sleeve sample, wherein the surface of the epoxy resin sleeve sample is provided with a strain gauge,
a mechanical stress applying device, which comprises a clamp for clamping two sides of a tested sample and a torque wrench for applying stress to the tested sample,
and the strain gauge is connected with the strain gauge to measure mechanical stress data of a measured sample, and the measuring principle of the strain gauge is a Wheatstone bridge. For half-bridge one-to-one compensation connection, there are:
where K is a scaling factor, ε 1 、ε 2 The strain measured by the strain gauge is E is an excitation power supply, U is an output measurement signal R g1 、R g2 The resistance of the strain gage. The length and the sectional area of the wires connected with the strain gauges in each channel are the same by applying a half-bridge one-to-one compensation method, and the compensation workpiece and the tested workpiece are necessarily made of the same material and are in the same working environment.
An experiment platform provided with an experiment cavity for accommodating discharge medium and a thermocouple arranged in the experiment cavity for measuring temperature data in real time,
a heating table which is connected with the experiment cavity in a heat conduction way so as to heat the tested sample in the experiment cavity to a preset temperature,
a DC voltage generator for providing a DC voltage, which is connected to the high voltage needle electrode via a protection resistor,
an alternating voltage source for providing alternating voltage and connected to the high voltage pin electrode through a blocking capacitor,
a voltage divider connected to the DC voltage generator and the AC voltage source via a protection resistor to divide the DC voltage and the AC voltage,
a harmonic source connected to the high-voltage needle electrode via a protection resistor to superimpose various types of voltage waveforms, a sample to be measured flowing in from the high-voltage needle electrode via high voltage electricity and discharging to the ground electrode to generate an electric branch,
a CCD camera facing the tested sample to shoot image data of the growth process of the electric branch,
a partial discharge instrument for detecting partial discharge signals in the discharge process of the sample to be detected,
and a processor connected to the strain gauge, thermocouple, CCD camera and partial discharge meter to collect and process the mechanical stress data, temperature data, image data and partial discharge signals.
In a preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of the electric-thermal-mechanical coupling, the experimental platform further comprises an oscilloscope for measuring voltage waveforms, and the processor is connected with the oscilloscope to correlate the voltage waveforms with the mechanical stress data, the temperature data, the image data and the partial discharge signals.
In a preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of the electro-thermo-mechanical coupling, the experimental platform is provided with a transmission light source for irradiating the experimental cavity, which is positioned at the side of the experimental cavity opposite to the CCD camera.
In the preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the electric stress is provided by an alternating voltage source, a direct voltage generator and a harmonic source, the thermal stress provides heat for a tested sample by adopting an oil bath heating mode through a heating table below an experimental cavity, and the mechanical stress rotates a nut for clamping the sample through a torque wrench, so that the compressive stress borne by the tested sample is measured by a strain gauge to reach a required stress level.
In the preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical, the partial discharge instrument measures partial discharge signals in a combined mode of an ultrasonic detection method and a pulse current method, and the processor analyzes the partial discharge characteristics based on the partial discharge signals.
In a preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of the electric-thermal-mechanical coupling, the heating platform is a constant-temperature heating platform.
In a preferred embodiment of the epoxy resin material electrical branch degradation test platform under the action of the electro-thermo-mechanical coupling, the test platform comprises a direct current voltage generator, an alternating current voltage source, a voltage divider, a harmonic source and various elements connected with the direct current voltage generator, the alternating current voltage source, the voltage divider, the harmonic source, such as a blocking capacitor, a filter capacitor and a protection resistor. The direct current voltage generator is responsible for providing the direct current voltage required by the system and is connected to the high voltage pin electrode through the silicon stack and the protection resistor. The alternating voltage source introduces an alternating electric field and is connected to the high voltage pin electrode by a blocking capacitor. The voltage divider is connected with a direct-current voltage generator and an alternating-current voltage source through a protection resistor and divides the direct-current voltage generator and the alternating-current voltage source respectively. The harmonic source is connected to the high voltage pin electrode through a protection resistor to superimpose various voltage waveforms.
In the experiment, the sample to be tested flows in from the high-voltage needle electrode through high-voltage electricity and discharges to the ground electrode to form an electric branch. The connection modes and the synergistic effect of the elements enable the experimental platform to simulate various voltage conditions, and provide a rich experimental environment for deep understanding of the degradation state of the tested sample. In the preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of the electric-thermal-mechanical coupling, the calculation formula of the mechanical stress applied by the torque wrench is as follows:
wherein F is the tightening force of the bolt on the tested sample, F t The tightening force applied to the single-sided bolt, M t The screw bolt tightening torque is sigma the stress applied to two sides of a measured sample, S is the cross-sectional area of a clamped plane of the measured sample, k is a dimensionless proportionality coefficient, according to the screw bolt model, the screw bolt tightening torque is referred to in the mechanical design handbook, and is 0.3, and d is the nut diameter of the torque wrench.
In a preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of electric-thermal-mechanical coupling, the tested sample is immersed in the discharge medium, and the discharge medium comprises transformer oil, silicone oil or insulating vegetable oil.
In a preferred embodiment of the experimental platform for the electrical branch degradation of the epoxy resin material under the action of electric-thermal-mechanical coupling, the tested sample comprises an epoxy impregnated paper or an epoxy sleeve sample.
The experimental method of the experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of the electric-thermal-mechanical comprises the following steps,
preparing a tested sample, pouring epoxy resin and a curing agent into a three-necked flask according to a mass ratio of 100:85, mixing to form a mixture, placing the mixture into a stirrer, stirring in vacuum, uniformly mixing, and removing air in the mixture;
placing crepe paper in a mould and presetting an electrode, controlling the distance between the tip of a high-voltage needle electrode and a ground electrode to be 2+/-0.2 mm, pouring the mixture into the mould of the preset electrode, and solidifying at constant temperature after vacuum degassing treatment in a vacuum drying oven to obtain a tested sample;
the method comprises the steps that a measured sample is clamped by a mechanical stress applying device and then immersed in a discharge medium in an experiment cavity, an alternating current voltage source, a direct current voltage generator and a harmonic wave provide electric stress, a heating table below the experiment cavity provides preset temperature for thermal stress, the mechanical stress is provided by a torque wrench, the measured sample flows in from a high-voltage needle electrode through high-voltage electricity and is discharged to a ground electrode to generate an electric branch, a CCD camera shoots image data of the electric branch in a growth process, a partial discharge meter detects partial discharge signals in the discharge process of the measured sample, a strain meter measures mechanical stress data of the measured sample, and a thermocouple measures temperature data of the measured sample in real time.
In one embodiment, as shown in fig. 2, the test sample comprises a high-voltage needle electrode prefabricated in epoxy resin, high-voltage electricity flows in from the high-voltage needle electrode at the upper part and discharges towards the direction of the ground electrode, and traces generated in the discharging process generate electric branches on the test sample, so that comparison and recording of subsequent processes are facilitated. According to some preferred embodiments of the present application, wherein preparing a rectangular parallelepiped epoxy impregnated paper or pure epoxy test sample of pre-needle electrodes may comprise the steps of:
s1, pouring epoxy resin and a curing agent into a clean three-necked flask according to the mass ratio of 100:85;
s2, placing the mixture into a stirrer with the rotating speed of 150r/min, stirring for 30 minutes in vacuum, uniformly mixing the mixture, and fully removing air in the mixture;
s3, placing the crepe paper in a designed die, presetting an electrode, controlling the distance between the tip of a high-voltage needle electrode and a ground electrode to be 2+/-0.2 mm, and pouring the mixture into the die of the preset electrode
S4, placing the fiber into a vacuum drying oven at 70 ℃ for vacuum degassing treatment of a second round for 30min, and ensuring that the fiber and the epoxy are fully infiltrated;
s5, placing the sample into a constant temperature box at 100 ℃ for curing for 10 hours, and then curing the sample in the constant temperature box at 130 ℃ for 10 hours for secondary curing;
and S6, after the preset time is reached, taking out the sample, cooling to the room temperature, and removing the mold to obtain the epoxy impregnated paper sample.
Further, the construction of the electrical branch degradation observation experiment platform specifically comprises the following steps:
as shown in figure 1, the experimental platform for observing the degradation of the electrical branch under the combined action of the electricity, the heat and the machine is shown.
The voltage regulator is connected with a laboratory power supply and can convert laboratory voltage into required high-voltage power;
the cavity contains discharge medium, and in the discharge experiment, the discharge electrode and the test sample work in the cavity.
Recording equipment capable of observing and recording the electrical dendronization process of the sample in the cavity; the electrical dendrite growth process is typically photographed by a CCD camera and then recorded by a processor for characterizing the electrical dendrite status of the casing sample.
The partial discharge instrument can detect partial discharge signals in the discharge process and is used for representing the partial discharge characteristics in the discharge process.
In addition, the experiment platform is reliably grounded; the test sample is immersed in the liquid medium, so that the interference of creeping discharge can be avoided;
further, during the test, the sample may be immersed in an insulating oil, which may be transformer oil, silicone oil or insulating vegetable oil.
The experimental platform can observe and record the discharge process of the sleeve sample in the experimental cavity through the recording equipment; shooting an electrical dendrite process by a CCD camera to represent the growth characteristics of the electrical dendrite in the discharge process; the partial discharge signal in the discharge process can be detected through the partial discharge tester and is used for representing the partial discharge characteristic in the discharge process, so that the degradation state of the sleeve sample is represented through the combination of the electric branch growth characteristic and the partial discharge characteristic, and the electric branch growth characteristic, the partial discharge capacity and the phase are related. The experimental platform simulates the working state of the sleeve during operation by applying electric stress, thermal stress and mechanical stress to the sleeve sample, and provides a brand-new means for researching the degradation condition of the sleeve sample and analyzing the insulation failure mechanism under the action of multiple stresses.
In one embodiment, the epoxy resin material electrical branch degradation experiment platform under the action of the electric-thermal-mechanical coupling comprises a combination of various instruments and devices such as an alternating current voltage source, a direct current voltage generator, a harmonic source, a voltage divider, an oscilloscope, a partial discharge detector and the like. The electrical stress in the experimental platform is provided by an alternating current voltage source, a direct current voltage generator and a harmonic to simulate the change of the electrical stress in the real working environment. The thermal stress part is formed by providing heat for the sample by adopting an oil bath heating mode through a constant temperature heating table below the experimental cavity, and the temperature of the constant temperature heating table is adjustable. The application of mechanical stress mainly depends on a torque wrench, the compressive stress measured by a strain gauge can reach experimental requirements by changing the applied stress, and a metal straight plate is arranged between a sample and a nut so as to ensure even distribution of the stress. The stress application should be based on the real number of the strain gauge, and the torque wrench calculates the stress application formula only to provide a rough stress application mode. In the experiment, the ultrasonic detection method and the pulse current method are used for jointly measuring the partial discharge.
In one embodiment, the bottom electrode is a gold-sprayed needle electrode during sample preparation to ensure good contact between the bottom of the sample and the ground electrode. The discharge medium in the experimental cavity is transformer oil, silicone oil or insulating vegetable oil. The electrical branch degradation experiment platform for the epoxy resin material under the coupling effect of the electric-thermal-mechanical device can provide a combined stress experiment platform for detecting the electrical branch degradation of the sleeve sample in a laboratory environment, and provides a brand-new means for researching the electrical branch degradation condition of the epoxy resin sample under the combined effect of the electric-thermal-mechanical device and analyzing an insulation failure mechanism.
In order to ensure uniform application of mechanical stress, a mode of applying stress by combining a strain gauge and a torque wrench is designed. A step of applying mechanical stress comprising: polishing a sample to be tested until the surface is smooth and is in a standard cuboid shape, and mounting strain flowers on the surface of the sample; measuring the length and width of the clamped plane of the sample, and roughly calculating the surface area of the clamped plane and the force required to apply the torque wrench; clamping the clamp to two sides of a sample to be tested, rotating the nut by using a torque wrench, and observing the indication of the strain gauge until the required stress is reached. In the experimental process, the electric stress, the thermal stress and the mechanical stress can be adjusted and changed according to actual requirements. The degradation state of the specimen is photographed and recorded in real time by a CCD camera to provide a visual reference. The constant temperature heating table of the experiment platform has the characteristics of rapidness and stability, and can be used for testing at different temperatures. The experimental platform provided by the invention is suitable for different types of power system equipment, and has universality and operability. In order to ensure the credibility of the experimental results, the experimental platform is subjected to repeated experiments and data verification. The experimental platform has higher stability and reliability, can continuously run for a long time, and is suitable for large-scale test requirements. The CCD camera of the experimental platform has high resolution and high sensitivity, and can shoot clear degradation images under high-speed operation. The invention can comprehensively and accurately evaluate the degradation degree of the sleeve sample under the condition of simulating the real working environment, and provides reliable technical support for the safe operation of the power system. The experimental platform has important application value in the field of electrical equipment, and provides technical support for improving the reliability and stability of a power system.
Before the strain gauge is attached to the surface of the sample, it is necessary to perform an appearance inspection and a resistance value. The appearance inspection is to inspect whether the strain gauge has rust spots or defects, and the resistance inspection is to inspect whether the strain gauge has short circuit or short circuit condition and whether the resistance is within the balance range of the strain gauge. The strain gauge is scrubbed by absolute ethyl alcohol before the patch is cleaned and dried for standby.
The basic principles of the present application have been described above in connection with specific embodiments, however, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are merely examples and not limiting, and these advantages, benefits, effects, etc. are not to be considered as necessarily possessed by the various embodiments of the present application. Furthermore, the specific details disclosed herein are for purposes of illustration and understanding only, and are not intended to be limiting, as the application is not intended to be limited to the details disclosed herein as such.
The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the application to the form disclosed herein. Although a number of example aspects and embodiments have been discussed above, a person of ordinary skill in the art will recognize certain variations, modifications, alterations, additions, and subcombinations thereof.
Claims (10)
1. An experimental platform for the electrical branch degradation of an epoxy resin material under the action of electric-thermal-mechanical coupling is characterized by comprising,
the sample to be tested comprises an epoxy resin sleeve sample, a high-voltage needle electrode inserted into the epoxy resin sleeve sample and a ground electrode arranged at the bottom of the epoxy resin sleeve sample, wherein the surface of the epoxy resin sleeve sample is provided with a strain gauge,
a mechanical stress applying device, which comprises a clamp for clamping two sides of a tested sample and a torque wrench for applying stress to the tested sample,
a strain gauge connected to the strain gauge for measuring mechanical stress data of the sample under test,
an experiment platform provided with an experiment cavity for accommodating discharge medium and a thermocouple arranged in the experiment cavity for measuring temperature data in real time,
a heating table which is connected with the experiment cavity in a heat conduction way so as to heat the tested sample in the experiment cavity to a preset temperature,
a DC voltage generator for providing a DC voltage, which is connected to the high voltage needle electrode via a protection resistor,
an alternating voltage source for providing alternating voltage and connected to the high voltage pin electrode through a blocking capacitor,
a voltage divider connected to the DC voltage generator and the AC voltage source via a protection resistor to divide the DC voltage and the AC voltage,
a harmonic source connected to the high-voltage needle electrode via a protection resistor to superimpose various types of voltage waveforms, a sample to be measured flowing in from the high-voltage needle electrode via high voltage electricity and discharging to the ground electrode to generate an electric branch,
a CCD camera facing the tested sample to shoot image data of the growth process of the electric branch,
a partial discharge instrument for detecting partial discharge signals in the discharge process of the sample to be detected,
and a processor connected to the strain gauge, thermocouple, CCD camera and partial discharge meter to collect and process the mechanical stress data, temperature data, image data and partial discharge signals.
2. The electrical dendrite degradation experiment platform of an epoxy material of claim 1 further comprising an oscilloscope for measuring a voltage waveform, wherein the processor is coupled to the oscilloscope to correlate the voltage waveform with said mechanical stress data, temperature data, image data and partial discharge signals.
3. An electrical dendrite degradation experiment platform of an epoxy material under electro-thermo-mechanical coupling as claimed in claim 1 wherein said experiment platform is provided with a transmission light source illuminating the experiment cavity at the side of the experiment cavity opposite to said CCD camera.
4. The experimental platform for the electrical branch degradation of the epoxy resin material under the coupling effect of an electric machine and an electric machine according to claim 2, wherein the electric stress is provided by an alternating voltage source, a direct voltage generator and a harmonic source, the thermal stress is provided by a heating platform below the experimental cavity to a tested sample in an oil bath heating mode, and the mechanical stress rotates a nut for clamping the sample through a torque wrench, so that the compressive stress borne by the tested sample is measured by the strain gauge to reach a required stress level.
5. The experimental platform for electrical branch degradation of epoxy resin material under the coupling action of electric-thermal-mechanical as set forth in claim 1, wherein the partial discharge meter measures the partial discharge signal by using a combination of ultrasonic detection and pulse current method, and the processor analyzes the partial discharge characteristic based on the partial discharge signal.
6. The experimental platform for electrical branch degradation of epoxy resin material under the action of electric-thermal-mechanical coupling as set forth in claim 1, wherein the heating stage is a constant temperature heating stage.
7. The experimental platform for electrical branch degradation of epoxy resin material under the action of electro-thermo-mechanical coupling as set forth in claim 1, wherein the torque wrench applies a mechanical stress according to the formula:
wherein sigma is the stress applied to two sides of the measured sample, S is the cross-sectional area of the clamped plane of the measured sample, k is a dimensionless proportionality coefficient, and d is the nut diameter of the torque wrench.
8. The experimental platform for electrical branch degradation of epoxy resin material under the action of electric-thermal-mechanical coupling as claimed in claim 1, wherein the tested sample is immersed in the discharge medium, and the discharge medium comprises transformer oil, silicone oil or insulating vegetable oil.
9. The electrical dendrite degradation test platform of an epoxy material of claim 1 wherein said test sample comprises an epoxy impregnated paper or an epoxy sleeve specimen.
10. An experimental method of an electrical branch degradation experimental platform of an epoxy resin material under the action of electric-thermal-mechanical coupling according to any one of claim 1-9, which is characterized by comprising the following steps,
preparing a tested sample, pouring epoxy resin and a curing agent into a three-necked flask according to a mass ratio of 100:85, mixing to form a mixture, placing the mixture into a stirrer, stirring in vacuum, uniformly mixing, and removing air in the mixture;
placing crepe paper in a mould and presetting an electrode, controlling the distance between the tip of a high-voltage needle electrode and a ground electrode to be 2+/-0.2 mm, pouring the mixture into the mould of the preset electrode, and solidifying at constant temperature after vacuum degassing treatment in a vacuum drying oven to obtain a tested sample;
the method comprises the steps that a measured sample is clamped by a mechanical stress applying device and then immersed in a discharge medium in an experiment cavity, an alternating current voltage source, a direct current voltage generator and a harmonic wave provide electric stress, a heating table below the experiment cavity provides preset temperature for thermal stress, the mechanical stress is provided by a torque wrench, the measured sample flows in from a high-voltage needle electrode through high-voltage electricity and is discharged to a ground electrode to generate an electric branch, a CCD camera shoots image data of the electric branch in a growth process, a partial discharge meter detects partial discharge signals in the discharge process of the measured sample, a strain meter measures mechanical stress data of the measured sample, and a thermocouple measures temperature data of the measured sample in real time.
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