Gap defect thickness regulating device and regulating method for space charge measurement

Abstract

A device and method for controlling the thickness of air gap defects for space charge measurement includes an aluminum electrode, a piezoelectric sensor below the aluminum electrode, a test sample lower piece above the aluminum electrode, a rigid partition suspended above the aluminum electrode and the test sample lower piece, the rigid partition having a through test hole and covered by an upper test sample; above the upper test sample, a horizontal bar with adjustable height driven by a vertical measuring instrument is arranged, a micrometer is arranged on the horizontal bar, a high-voltage electrode is arranged below the micrometer, the high-voltage electrode is connected to a high-voltage power supply, and the high-voltage electrode is aligned with the test hole of the rigid partition. The air gap defect thickness control device provided by this invention can achieve micron-level quantitative control of the air gap, effectively evaluating the influence of tiny air gap thickness on space charge distribution.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage insulating dielectric testing technology, and relates to a device and method for adjusting the thickness of air gap defects for space charge measurement. Specifically, it relates to a device that can accurately simulate and controllably adjust the thickness of air gap defects in insulating materials, and its application in space charge distribution measurement. Background Technology

[0002] The insulation of power transmission and energy storage equipment such as high-voltage cables and film capacitors directly determines the reliability of the equipment. As the equipment ages, the insulation material deteriorates and structural defects appear, making it prone to insulation breakdown and electrical accidents. In high-voltage cable joints, micro-gaps can develop between the main insulation and the joint insulation during long-term service, inducing local electric field distortion and leading to joint breakdown. In film capacitors, initial air gap defects introduced during manufacturing and repeated thermal expansion and contraction causing separation between film layers and creating new air gap defects can both lead to capacitor parameter drift and even short-circuit breakdown.

[0003] Insulating materials accumulate space charge under a polarized electric field. The dielectric constant of air gap defects differs significantly from that of the insulating material, leading to localized space charge concentration and severe distortion of the electric field distribution due to this dielectric constant mismatch. Air gap defects are often concealed and difficult to observe with the naked eye. Their presence can result in enhanced local electric fields and reduced discharge initiation voltage, posing a potential threat to the safe operation of the insulation system. Therefore, accurately simulating air gap defects and quantitatively analyzing their impact on space charge behavior and electric field distribution is an important research direction for insulation assessment.

[0004] The two existing space charge measurement techniques, pulsed electroacoustic method and thermally stimulated current method, usually involve placing the insulating sample tightly between two electrodes for pressure and testing. This makes it difficult to accurately and repeatably control the thickness of air gap defects in the sample under test, and cannot quantitatively assess the impact of air gap defects on space charge.

[0005] Currently, the simulation of air gap defect thickness suffers from drawbacks such as low control precision, poor repeatability of air gap defects, and inability to monitor changes in air gap defects during experiments. Therefore, there is an urgent need for a device and method that can accurately control the thickness of air gap defects and link it with a space charge measurement system to achieve controllable and repeatable air gap defect simulation, providing a reliable experimental basis for the study of space charge characteristics, electric field distortion laws, and insulation degradation mechanisms of insulating materials.

[0006] Chinese patent application 201720010410.3 provides a test device for simulating air gap defects in solid insulating materials. By setting up multiple air gap defect discharge defect models of different sizes such as 1mm, 2mm, and 3mm, the device can freely switch the defect model according to the test conditions to simulate air gap defects of different sizes in insulation, thereby simulating air gap defects in solid insulating materials. However, this device is difficult to effectively simulate micron-level interface air gap defects that occur in actual engineering. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a device and method for adjusting the thickness of air gap defects in space charge measurement. This overcomes the problems of inaccurate control, poor repeatability, and inability to monitor air gap defects in real time in existing space charge measurements. Furthermore, it achieves micron-level adjustment and stable maintenance of air gap thickness by determining the contact zero point through high-precision displacement and mechanical feedback.

[0008] The present invention adopts the following technical solution, including a test sample, an aluminum electrode, a high-voltage power supply and a high-voltage electrode, and the air gap defect thickness control device further includes a rigid partition, a piezoelectric sensor, a vertical measuring instrument and a micrometer.

[0009] The piezoelectric sensor is disposed below the aluminum electrode, and a test sample lower sheet is disposed above the aluminum electrode. The rigid partition is suspended above the aluminum electrode and the test sample lower sheet. The rigid partition has a through test hole and is covered with the test sample upper sheet.

[0010] Above the sample to be tested, a crossbar driven by a vertical measuring instrument is provided. A micrometer is provided on the crossbar, and a high-voltage electrode is provided below the micrometer. The high-voltage electrode is connected to a high-voltage power supply and is aligned with the test hole of the rigid partition.

[0011] Furthermore, the vertical measuring instrument includes a vertical pole with graduations and a horizontal bar that is perpendicular to the vertical pole, with one end slidingly fixed along the vertical direction of the vertical pole and rotating horizontally around the vertical pole.

[0012] The micrometer is slidably mounted on the crossbar and can be adjusted horizontally along the crossbar. The micrometer can also adjust the height of its end in the vertical direction. In conjunction with the vertical measuring instrument, the micrometer can adjust the spatial position of the high-voltage electrode above the rigid partition and accurately locate the height of the high-voltage electrode in the vertical direction.

[0013] Furthermore, one or more micrometers are provided, and the horizontal position of the micrometers on the crossbar is adjustable.

[0014] Furthermore, the cross-sectional shape of the high-voltage electrode matches the cross-sectional shape of the test hole on the rigid partition, and the cross-sectional dimension of the high-voltage electrode is smaller than the diameter of the test hole on the rigid partition.

[0015] Furthermore, the piezoelectric sensor is a PVDF piezoelectric thin film sensor, used to detect the contact state between the high-voltage electrode and the test sample placed on the rigid partition.

[0016] A second aspect of the present invention provides a method for controlling the thickness of air gap defects for space charge measurement, specifically comprising:

[0017] Place the test sample sheet above the aluminum electrode;

[0018] The sample to be tested is placed on top of the rigid partition;

[0019] Operate the vertical measuring instrument and the micrometer screw gauge to drive the high-voltage electrode to move downwards until the output signal of the piezoelectric sensor indicates that the contact zero point has been reached.

[0020] The high-voltage electrode is driven to move upward from the contact zero point by a calibrated displacement amount. ;

[0021] The calibration displacement is compensated by system calibration. To obtain air gap defects;

[0022] A pulsed high voltage is applied to the high voltage electrode through the high voltage power supply, and space charge data is collected through the piezoelectric sensor and the space charge signal collection module.

[0023] Further, the vertical measuring instrument and the micrometer are adjusted to drive the high-voltage electrode downwards until the piezoelectric sensor outputs a signal that the high-voltage electrode has reached the zero-point of contact. The zero-point of contact is then determined, and the micrometer is adjusted to drive the high-voltage electrode upwards from the zero-point of contact to calibrate the displacement. , thus obtaining air gap defects.

[0024] Furthermore, the contact zero point is the corresponding position of the upper and lower test samples when the output signal of the piezoelectric sensor undergoes a sudden change.

[0025] Based on the inversion calculation of the acquired space charge signal, the space charge density distribution inside the test sample is obtained. The local electric field intensity distribution was calculated based on the Poisson equation. and electric field distortion rate .

[0026] A third aspect of the present invention provides a terminal, including a processor and a storage medium;

[0027] The storage medium is used to store instructions;

[0028] The processor is configured to operate according to the instructions to execute steps of a method for controlling the thickness of air gap defects for space charge measurement.

[0029] A fourth aspect of the invention provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of a method for controlling the thickness of an air gap defect for space charge measurement.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: The air gap defect thickness control device of the present invention determines the contact zero point between the high-voltage electrode and the test sample through the electrical signal of the piezoelectric sensor, and controls the high-voltage electrode to move precisely upward from the contact zero point by a preset displacement by jointly controlling the micrometer screw gauge and the vertical measuring instrument, thereby forming a simulated air gap defect in the area corresponding to the test hole, and realizing the controllability of the air gap defect thickness. By controlling the preset displacement, micron-level quantitative control of the air gap can be achieved, effectively evaluating the influence of the tiny air gap thickness on the space charge distribution. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the air gap defect thickness control device of the present invention;

[0032] Figure 2 This is a schematic diagram of the air gap thickness defect control device of the present invention.

[0033] Figure 3 These are measured data diagrams of space charge of the air gap defect thickness control device of the present invention. (a) is a measured data diagram of space charge of a 5 μm thick air gap defect sample; (b) is a measured data diagram of space charge of a 10 μm thick air gap defect sample.

[0034] In the figure: 1. Test sample; 101. Test sample upper part; 102. Test sample lower part; 2. Rigid partition; 3. Aluminum electrode; 4. Piezoelectric sensor; 5. High voltage power supply; 6. High voltage electrode; 7. Micrometer screw gauge; 8. Vertical measuring instrument; 9. Space charge signal collection module; 10. Aluminum electrode signal peak; 11. Signal peak at the defect; 12. High voltage electrode signal peak. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0036] like Figures 1-3Embodiment 1 of the present invention provides an air gap defect thickness control device for space charge measurement, specifically comprising:

[0037] like Figure 1 and Figure 2 As shown, the air gap defect thickness control device includes: a test sample 1, an aluminum electrode 3, a high-voltage power supply 5 and a high-voltage electrode 6, as well as a rigid partition 2, a piezoelectric sensor 4, a vertical measuring instrument 8, and a micrometer 7.

[0038] Test sample 1 includes an upper test sample sheet 101 and a lower test sample sheet 102, which are pressed by a flat vulcanizing machine. The materials of the upper test sample sheet 101 and the lower test sample sheet 102 are the same as the insulating medium material to be simulated. Both test sample sheets are made of cross-linked polyethylene to simulate air gap defects in the cable insulation medium. Two test sample sheets are also made of two different materials: cross-linked polyethylene and silicone rubber, to simulate air gap defects at the junction of the two materials in a cable joint.

[0039] The lower sample sheet 102 is placed on top of the aluminum electrode 3. A rigid partition 2 is suspended above the aluminum electrode 3 and the lower sample sheet 102. The rigid partition 2 has through-holes distributed in an array. The upper sample sheet 101 is placed on top of the rigid partition 2. The through-holes in the rigid partition 2 create an air gap defect between the upper sample sheet 101 and the lower sample sheet 102, and are used to determine the thickness of the air gap defect.

[0040] A piezoelectric sensor 4 is disposed below the aluminum electrode 3. In this embodiment, a PVDF piezoelectric thin film sensor is used to detect the contact state between the high-voltage electrode 6 and the test sample 1 placed on the rigid partition 2. A space charge signal collection module 9 is electrically connected below the piezoelectric sensor 4 to collect space charge data.

[0041] The vertical measuring instrument 8 includes a vertically oriented upright rod with graduations and a horizontal rod perpendicular to the upright rod, with one end sliding and fixed along the vertical direction of the upright rod and rotating horizontally around the upright rod. The horizontal rod is positioned above the test sample plate 101 and is used to adjust the height of the horizontal rod. A horizontally adjustable micrometer 7 is slidably mounted on the horizontal rod. The micrometer 7 works in conjunction with the vertical measuring instrument 8 to adjust the spatial position of the high-voltage electrode 6 above the rigid partition 2 and accurately position the height of the high-voltage electrode 6 in the vertical direction. In this embodiment, a pulsed high voltage is applied to the high-voltage electrode 6 and the test sample 1 by a high-voltage power supply 5, and space charge signal data is collected by a piezoelectric sensor 4 and a space charge signal collection module 9.

[0042] The number of micrometers 7 is one or more. The height of the horizontal bar is adjusted by the vertical measuring instrument 8, and the height of the high-voltage electrode 6 is accurately positioned by the fine-tuning of the micrometers 7. The horizontal position is adjusted by sliding the micrometers 7 to ensure that the high-voltage electrode 6 is aligned with the air gap thickness of all test holes in the rigid partition 2. The high-voltage electrode 6 is positioned below the micrometers 7 and is connected to the high-voltage power supply 5. The high-voltage electrode 6 is aligned with the test holes in the rigid partition 2. The cross-sectional shape of the high-voltage electrode 6 matches the cross-sectional shape of the test holes on the rigid partition 2, and the cross-sectional dimension of the high-voltage electrode 6 is smaller than the diameter of the test holes on the rigid partition 2.

[0043] In this embodiment, in the unenergized state, the piezoelectric sensor 4 displays zero. The high-voltage electrode 6 is aligned with the test hole of the rigid partition 2. By jointly adjusting the vertical measuring instrument 8 and the micrometer 7, the high-voltage electrode 6 moves downwards, bringing the upper sample 101 and lower sample 102 into contact. The piezoelectric sensor 4 detects the contact force between the upper and lower sample 101 and outputs a corresponding electrical signal. When the piezoelectric sensor 4 detects contact between the upper and lower sample 101, its reading changes abruptly. At this point, the upper and lower sample 101 are considered to be just in contact, and their corresponding positional relationship is considered the contact zero point. The high-voltage electrode 6 is then controlled to move upwards from the contact zero point to calibrate the displacement. Perform system calibration and compensation to determine the displacement of the calibration point. The thickness in the area corresponding to the test hole is the measured thickness of the air gap defect. This embodiment uses a calibration displacement setting. The size of the defect can be adjusted to control the thickness of the air gap.

[0044] like Figure 3 As shown in (a) and (b), the vertical axis represents the voltage amplitude, which is linearly related to the charge. It can be seen from the figures that a defect signal peak 11 appears between the aluminum electrode signal peak 10 and the high-voltage electrode signal peak 12. In the 5µm air gap defect sample, the value of the aluminum electrode signal peak 10 is 40.0mV, located approximately 202ns from the air gap defect, with a peak value of approximately 3.2mV. In the 10µm air gap defect sample, the value of the aluminum electrode signal peak 10 is 42.1mV, located approximately 204ns from the air gap defect, with a peak value of approximately 3.5mV. Therefore, increasing the air gap defect size leads to an increase in charge density at the aluminum electrode signal peak 10, a change in the peak charge position at the air gap defect, and an increase in the value of the defect signal peak 11.

[0045] Embodiment 2 of the present invention provides a method for controlling the thickness of air gap defects for space charge measurement, specifically including:

[0046] Place the test sample 102 above the aluminum electrode 3;

[0047] Cover the rigid partition 2 with the test sample plate 101;

[0048] Operate the vertical measuring instrument 8 and the micrometer screw gauge 7 to drive the high voltage electrode 6 to move downwards until the output signal of the piezoelectric sensor 4 indicates that the contact zero point has been reached.

[0049] Drive the high-voltage electrode 6 to move upward from the contact zero point to calibrate the displacement. ;

[0050] The calibration displacement is compensated by system calibration. To obtain air gap defects;

[0051] A pulsed high voltage is applied to the high voltage electrode 6 by the high voltage power supply 5, and space charge data is collected by the piezoelectric sensor 4 and the space charge signal collection module 9.

[0052] Specifically, the space charge density distribution inside the sample under test is obtained by inversion calculation based on the collected space charge signal. The local electric field intensity distribution was calculated based on the Poisson equation. and electric field distortion rate .

[0053] The voltage-time signal acquired from the space charge signal collection module 9 via convolution operation The space charge signal source is extracted, and the calculation process is as follows:

[0054] ;

[0055] in, For system transfer function, Space charge signal source Position within the medium;

[0056] Sound waves travel at speed Propagation, position within the medium The relationship between the arrival time of the sound wave and the time of arrival is as follows:

[0057] ;

[0058] Represented as a time function The Fourier transform is performed using the frequency domain deconvolution method, and the formula is as follows:

[0059] ;

[0060] get:

[0061] ;

[0062] Based on the Poisson equation, the space charge density distribution Perform integration to calculate the local electric field intensity distribution inside the sample. The formula is:

[0063] ;

[0064] in, It is the dielectric constant;

[0065] Distribution of local electric field intensity With an ideal uniform electric field By comparison, the electric field distortion rate is obtained. The formula is:

[0066] ;

[0067] electric field distortion rate It is sufficient to quantify the degree of disturbance to the local electric field caused by air gap defects or space charge accumulation.

[0068] By analyzing the air gap defects of different thicknesses, morphology, and distribution conditions By studying the variation patterns of electric field concentration, we can assess the severity of electric field concentration and its impact on the insulation dielectric's breakdown and charge migration stability. Furthermore, by combining time-resolved space charge measurements, we can investigate the dynamic process of electric field distortion as a function of applied voltage, temperature, or time, thereby revealing the intrinsic correlation mechanism between electric field non-uniformity caused by air gap defects and insulation aging.

[0069] Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium;

[0070] The storage medium is used to store instructions;

[0071] The processor is configured to operate according to the instructions to execute steps of a method for controlling the thickness of air gap defects for space charge measurement.

[0072] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a method for controlling the thickness of air gap defects for space charge measurement.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A device for adjusting the thickness of air gap defects for space charge measurement, comprising a test sample (1), an aluminum electrode (3), a high-voltage power supply (5), and a high-voltage electrode (6), characterized in that: The air gap defect thickness control device also includes a rigid partition (2), a piezoelectric sensor (4), a vertical measuring instrument (8), and a micrometer (7). The piezoelectric sensor (4) is disposed below the aluminum electrode (3), and a test sample lower piece (102) is disposed above the aluminum electrode (3). The rigid partition (2) is suspended above the aluminum electrode (3) and the test sample lower piece (102). The rigid partition (2) has a through test hole and is covered with a test sample upper piece (101). Above the sample plate (101) to be tested, there is a crossbar driven by a vertical measuring instrument (8), a micrometer (7) is provided on the crossbar, and a high voltage electrode (6) is provided below the micrometer (7). The high voltage electrode (6) is connected to a high voltage power supply (5), and the high voltage electrode (6) is aligned with the test hole of the rigid partition (2). The micrometer (7) can also adjust the height of its end in the vertical direction; the micrometer (7) works in conjunction with the vertical measuring instrument (8) to adjust the spatial position of the high voltage electrode (6) above the rigid partition (2) and accurately position the height of the high voltage electrode (6) in the vertical direction; Adjust the vertical measuring instrument (8) and the micrometer screw gauge (7) to drive the high-voltage electrode (6) downward until the piezoelectric sensor (4) outputs a signal that the high-voltage electrode (6) has reached the zero contact point. Determine the zero contact point, and adjust the micrometer screw gauge (7) to drive the high-voltage electrode (6) to move upward from the zero contact point to calibrate the displacement. , thus obtaining air gap defects.

2. The air gap defect thickness control device for space charge measurement according to claim 1, characterized in that, The vertical measuring instrument (8) includes a vertical pole with graduations in the vertical direction, and a horizontal bar that is perpendicular to the vertical pole and has one end that is slidably fixed in the vertical direction of the vertical pole and rotates horizontally around the vertical pole. The micrometer (7) is slidably mounted on the crossbar and adjusted horizontally along the direction of the crossbar.

3. The air gap defect thickness control device for space charge measurement according to claim 1 or 2, characterized in that, One or more micrometers (7) are provided, and the horizontal position of the micrometers (7) on the crossbar is adjustable.

4. The air gap defect thickness control device for space charge measurement according to claim 1, characterized in that, The cross-sectional shape of the high-voltage electrode (6) matches the cross-sectional shape of the test hole on the rigid partition (2), and the cross-sectional size of the high-voltage electrode (6) is smaller than the diameter of the test hole on the rigid partition (2).

5. The air gap defect thickness control device for space charge measurement according to claim 1, characterized in that, The piezoelectric sensor (4) is a PVDF piezoelectric film sensor used to detect the contact state between the high-voltage electrode (6) and the test sample (1) placed on the rigid partition (2).

6. A method for controlling the thickness of air gap defects for space charge measurement based on the control device described in any one of claims 1-5, characterized in that, Specifically, it includes: Place the test sample (102) above the aluminum electrode (3); The test sample plate (101) is placed over the rigid partition (2); Operate the vertical measuring instrument (8) and the micrometer screw gauge (7) to drive the high voltage electrode (6) to move down until the output signal of the piezoelectric sensor (4) indicates that the high voltage electrode (6) has reached the contact zero point; The high-voltage electrode (6) is driven to move upward from the contact zero point by a calibrated displacement amount. ; The calibration displacement is compensated by system calibration. To obtain air gap defects; A pulsed high voltage is applied to the high voltage electrode (6) by the high voltage power supply (5), and space charge data is collected by the piezoelectric sensor (4) and the space charge signal collection module (9).

7. The method for controlling the thickness of air gap defects for space charge measurement according to claim 6, characterized in that, The contact zero point is the corresponding position of the upper piece (101) and the lower piece (102) of the test sample when the output signal of the piezoelectric sensor (4) changes abruptly.

8. The method for controlling the thickness of air gap defects for space charge measurement according to claim 6, characterized in that, Based on the inversion calculation of the acquired space charge signal, the space charge density distribution inside the test sample is obtained. The local electric field intensity distribution was calculated based on the Poisson equation. and electric field distortion rate .

9. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 6-8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 6-8.

Images