Dry-type capacitive bushing defect simulation method and device

Abstract

The invention provides a dry-type capacitive bushing defect simulation method and device. The method comprises the following steps: respectively acquiring maximum electric field intensity and field intensity distribution characteristics of a three-dimensional model of a defective bushing and a three-dimensional model of a defect-free bushing; respectively acquiring insulation performance test data of the defective sleeve and the defect-free sleeve; and comparing and analyzing the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing and the insulation performance test data of the defective bushing and the defect-free bushing, and establishing a quantitative relationship between defect parameters and electrical insulation parameters. According to the method, the defects of the dry-type capacitive bushing can be simulated, accurate and systematic analysis is further carried out, and data support and theoretical basis are provided for insulation design optimization, manufacturing process improvement and operation state evaluation of the dry-type capacitive bushing.

Description

Technical Field

[0001] This invention relates to the field of high-voltage power equipment technology, and more specifically, to a method and apparatus for simulating defects in dry-type capacitor bushings. Background Technology

[0002] Epoxy-impregnated paper capacitor bushings are key equipment in power transmission and transformation projects, providing insulation and support for conductors passing through walls or enclosures. These bushings typically consist of a current-carrying rod, an epoxy-impregnated insulating paper capacitor core, and an outer silicone rubber insulating sheath. Through capacitor plate distribution design, the axial and radial electric field distribution of the bushing can be effectively optimized, ensuring its safe and stable operation under high voltage. However, during the manufacturing and operation of the bushing, various defects may occur inside the capacitor core due to factors such as poor manufacturing processes, material defects, mechanical stress, and thermal aging. These defects can include plate wrinkles, bubbles, and localized cracks. These defects can alter the electric field distribution inside the bushing, inducing partial discharge, accelerating the aging of the insulating material, and ultimately potentially leading to bushing breakdown, power outages, and significant economic losses.

[0003] The formation of internal defects in bushings is often random, and the location and morphology of defects have varying degrees of influence on the electric field. Furthermore, the development patterns of different defects differ during operation. To effectively distinguish defect types in experimental testing, it is necessary to simulate specific single defects within the bushing core and analyze the parameter changes during defect development. However, existing bushing defect studies largely rely on post-fault disassembly analysis, lacking systematic analysis and accurate simulation of typical defects. Summary of the Invention

[0004] In view of this, the present invention proposes a method for simulating defects in dry-type capacitive bushings, aiming to solve the problem of the lack of systematic analysis and accurate simulation of typical defects in epoxy-impregnated paper capacitive bushings in the prior art. The present invention also proposes a device for simulating defects in dry-type capacitive bushings.

[0005] In one aspect, the present invention proposes a method for simulating defects in dry-type capacitor bushings. The method includes the following steps: obtaining the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defective bushing and the defect-free bushing, respectively; obtaining the insulation performance test data of the defective bushing and the defect-free bushing, respectively; comparing and analyzing the maximum electric field strength, field strength distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defective bushing and the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, to establish a quantitative relationship between defect parameters and electrical insulation parameters.

[0006] Furthermore, in the above-mentioned dry capacitor bushing defect simulation method, before the steps of obtaining the maximum electric field strength and field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing respectively, the method further includes: determining the defect type and defect parameters, and preparing the defective bushing.

[0007] Furthermore, in the above-mentioned dry capacitor bushing defect simulation method, the defect types include one or more of the following: metallic foreign object defects, insulating foreign object defects, local crack defects, bubble defects, or plate wrinkles; the defect parameters include the location and size of the defect.

[0008] Furthermore, in the above-mentioned dry capacitor bushing defect simulation method, in the steps of determining the defect type and defect parameters and preparing the defective bushing, a sample block is prepared according to the defect type and defect parameters; the defective bushing is prepared according to the defect parameters and manufacturing process, and the sample block is embedded during the preparation process.

[0009] Furthermore, in the above-mentioned dry capacitor bushing defect simulation method, in the step of preparing a sample block according to the defect type and defect parameters, a sample block similar to the core material of a defect-free bushing is selected; when the defect type is a metallic foreign object defect, a metallic foreign object is placed in the sample block to form a defective sample block, and the defective sample block is embedded during the defective bushing preparation process; when the defect type is an insulating foreign object defect, an insulating foreign object is placed in the sample block to form a defective sample block, and the defective sample block is embedded during the defective bushing preparation process; when the defect type is a local crack defect, an air gap is created in the sample block to form a defective sample block, and the defective sample block is embedded during the defective bushing preparation process; when the defect type is a bubble defect, an air domain is embedded in the sample block to form a defective sample block, and the defective sample block is embedded during the defective bushing preparation process; when the defect type is an electrode wrinkle, a sample block is embedded during the defective bushing preparation process.

[0010] Furthermore, in the above-mentioned method for simulating defects in dry-type capacitor bushings, in the step of preparing a defective bushing according to defect parameters and manufacturing process, and embedding a sample block during the preparation process, when the defect type is any one of metallic foreign object defects, insulating foreign object defects, local crack defects, or bubble defects, when rolling the capacitor core of the defective bushing, when the plate before the defect position is finished, the core material is rolled to the designed diameter, and a pit is formed by hollowing out the core material at the defect position. The defect sample block is placed in the pit, and the defective bushing is prepared according to the manufacturing process. When the defect type is plate wrinkling, when rolling the capacitor core of the defective bushing, before the plate that needs wrinkling is finished, the core material at the corresponding defect position is hollowed out to form a pit. The sample block is used to press the plate that needs wrinkling into the pit, and then the core material is wound again. The defective bushing is then prepared according to the manufacturing process.

[0011] Furthermore, in the above-mentioned method for simulating defects in dry-type capacitor bushings, the steps of obtaining the maximum electric field intensity and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing are as follows: Three-dimensional models of the defective bushing and the defect-free bushing are established respectively, and the electric field distribution and radial electric field intensity of the capacitor core are simulated and calculated under the same voltage. The maximum electric field intensity and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing are obtained respectively. When performing electric field simulation calculations on the three-dimensional model of the defective bushing, the electric field distribution around the defect, the radial and axial electric field intensity curves of the capacitor core, and the location and range of the field strength concentration area are also obtained.

[0012] Furthermore, in the above-mentioned dry-type capacitor bushing defect simulation method, in the step of obtaining insulation performance test data of defective bushings and defect-free bushings respectively, insulation performance tests are performed on defective bushings and defect-free bushings respectively. During the test, starting from 0V, the voltage is increased at a preset rate. During the voltage increase process, the partial discharge signal of the bushing is continuously monitored, and the partial discharge initiation voltage of the bushing is recorded. After the voltage is increased to the rated operating voltage and stabilized, the partial discharge quantity, discharge phase distribution spectrum, capacitance, dielectric loss factor, and frequency domain dielectric spectrum of the bushing are measured and recorded.

[0013] Furthermore, in the aforementioned dry-type capacitor bushing defect simulation method, the step of comparing and analyzing the maximum electric field strength, field strength distribution characteristics, and insulation performance test data of the three-dimensional models of the defective bushing and the defect-free bushing to establish a quantitative relationship between defect parameters and electrical insulation parameters involves fitting the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing. Based on the fitted data, a quantitative relationship between defect parameters and electrical insulation parameters is established. The electrical insulation parameters include: maximum electric field strength, partial discharge initiation voltage, and partial discharge quantity.

[0014] In this invention, the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing are first obtained. Then, the insulation performance test data of the defective bushing and the defect-free bushing are obtained. The maximum electric field strength, field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, are compared and analyzed to establish a quantitative relationship between defect parameters and electrical insulation parameters. In this way, the defects of dry-type capacitor bushings can be simulated, and then accurately and systematically analyzed. This provides data support and theoretical basis for the insulation design optimization, manufacturing process improvement, and operational status evaluation of dry-type capacitor bushings, and solves the problem of lack of systematic analysis and accurate simulation of typical defects of epoxy-impregnated paper capacitor bushings in the prior art.

[0015] On the other hand, the present invention also proposes a dry-type capacitor bushing defect simulation device, which includes: an electric field acquisition unit for acquiring the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defective bushing; a test data acquisition unit for acquiring the insulation performance test data of the defective bushing and the defective bushing; and an analysis unit for comparing and analyzing the maximum electric field intensity, field intensity distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defective bushing and the defective bushing, as well as the insulation performance test data of the defective bushing and the defective bushing, to establish a quantitative relationship between defect parameters and electrical insulation parameters.

[0016] Since the dry-type capacitor bushing defect simulation method has the above-mentioned effects, the dry-type capacitor bushing defect simulation device also has the corresponding technical effects. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 A flowchart of a method for simulating defects in dry capacitor bushings provided in an embodiment of the present invention;

[0019] Figure 2 Another flowchart of the dry capacitor bushing defect simulation method provided in the embodiments of the present invention;

[0020] Figure 3 A schematic diagram of the defective bushing structure in the dry capacitor bushing defect simulation method provided in this embodiment of the invention;

[0021] Figure 4The radial electric field intensity distribution curve of the capacitor core under bubble defects in the dry capacitor bushing defect simulation method provided in the embodiments of the present invention;

[0022] Figure 5 The simulated electric field distribution diagram under bubble defects in the dry capacitor bushing defect simulation method provided in the embodiments of the present invention;

[0023] Figure 6 The power frequency partial discharge phase distribution diagram of the capacitor bushing under bubble defects in the dry capacitor bushing defect simulation method provided in the embodiments of the present invention;

[0024] Figure 7 This is a structural block diagram of the dry capacitor bushing defect simulation device provided in an embodiment of the present invention. Detailed Implementation

[0025] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Method Implementation Examples:

[0027] See Figure 1 , Figure 1 A flowchart illustrating a method for simulating defects in dry-type capacitor bushings according to an embodiment of the present invention. As shown in the figure, the method for simulating defects in dry-type capacitor bushings includes the following steps:

[0028] Step S1: Obtain the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, respectively.

[0029] Specifically, firstly, the model of the dry-type capacitor bushing is selected, and the defect type and defect parameters are determined according to the test requirements. Then, based on the model of the dry-type capacitor bushing, the corresponding design drawings, design requirements, and corresponding design standards are determined. Next, defect-free bushings are prepared according to the design drawings, design requirements, and design standards, and defective bushings are prepared according to the design drawings, design requirements, design standards, and defect parameters. Defect-free bushings can be prepared according to the test requirements, or pre-made bushings of the corresponding model can be selected; this embodiment does not impose any restrictions on this.

[0030] Both defect-free and defective bushings are manufactured using existing dry-type capacitor bushing manufacturing processes.

[0031] After preparing the defective and defect-free bushings, three-dimensional models of both were created. Electric field simulation analyses were then performed on both models to obtain the maximum electric field intensity and field distribution characteristics. Specifically, the three-dimensional model of the defect-free bushing can be pre-constructed based on the design drawings, and the three-dimensional model of the defective bushing can also be pre-constructed based on the design drawings and defect parameters.

[0032] Step S2: Obtain insulation performance test data for defective bushings and defect-free bushings respectively.

[0033] Specifically, insulation performance tests were conducted on defective bushings and defect-free bushings respectively, and the insulation performance test data were recorded separately.

[0034] Step S3 involves comparing and analyzing the maximum electric field strength, field strength distribution characteristics, and insulation performance test data of the defective bushing and the defect-free bushing in their three-dimensional models to establish a quantitative relationship between defect parameters and electrical insulation parameters.

[0035] Specifically, the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of defective and defect-free bushings, as well as the insulation performance test data of defective and defect-free bushings, are fitted. Based on the fitted data, a quantitative relationship between defect parameters and electrical insulation parameters is established. Among them, electrical insulation parameters include: maximum electric field strength, partial discharge initiation voltage, and partial discharge quantity.

[0036] As can be seen, in this embodiment, the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing are first obtained respectively. Then, the insulation performance test data of the defective bushing and the defect-free bushing are obtained respectively. Then, the maximum electric field strength, field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing are compared and analyzed to establish a quantitative relationship between defect parameters and electrical insulation parameters. In this way, the defects of dry-type capacitor bushings can be simulated, and then accurately and systematically analyzed. This provides data support and theoretical basis for the insulation design optimization, manufacturing process improvement and operation status evaluation of dry-type capacitor bushings, and solves the problem of lack of systematic analysis and accurate simulation of typical defects of epoxy-impregnated paper capacitor bushings in the prior art.

[0037] See Figure 2 , Figure 2This is another flowchart of the dry-type capacitor bushing defect simulation method provided in this embodiment of the invention. As shown in the figure, the dry-type capacitor bushing defect simulation method includes the following steps:

[0038] Step S4: Determine the defect type and defect parameters, and prepare the defect sleeve.

[0039] Specifically, based on the experimental requirements, the defect type and defect parameters are determined. Then, based on the determined defect type and defect parameters, the defective bushing is prepared according to the manufacturing process of dry-type capacitor bushings. The manufacturing process of dry-type capacitor bushings can refer to existing technologies, and will not be described in detail here.

[0040] Defect types include one or more of the following: metallic foreign matter defects, insulating foreign matter defects, localized crack defects, bubble defects, or electrode wrinkles.

[0041] Defect parameters include: the location of the defect and the size of the defect.

[0042] Step S4 further includes:

[0043] Sub-step S41: Prepare a sample block according to the defect type and defect parameters.

[0044] Specifically, a sample block similar to the core material of the defect-free bushing is selected. In other words, for various defect types, modular design of defects is achieved using a sample block similar to the core material of the defect-free bushing. When this dry-type capacitor bushing defect simulation method is used for epoxy-impregnated paper capacitor bushings, and the defect-free bushing is an epoxy-impregnated paper bushing, then an epoxy resin block with a composition similar to the core material of the epoxy-impregnated paper bushing is selected as the sample block.

[0045] When the defect type is a metallic foreign object defect, a metallic foreign object is placed in the sample block to form a defect sample block, which is then embedded during the defect sleeve preparation process. Specifically, a tiny cylindrical or spherical metallic foreign object, made of copper or aluminum, is placed in the sample block to simulate a metallic foreign object defect formed inside the sleeve core. The dimensions of the defect include the diameter and height of the foreign object.

[0046] When the defect type is an insulating foreign object defect, an insulating foreign object is placed in the sample block to form a defect sample block, which is then embedded during the defective bushing preparation process. Specifically, a tiny cylindrical or spherical insulating material foreign object is placed in the sample block to simulate the insulating foreign object defect formed inside the bushing core. The defect parameters include: the size of the foreign object and the dielectric constant of the insulating material.

[0047] When the defect type is a localized crack, an air gap is created in the sample block to form a defect sample block, which is then embedded during the fabrication of the defective sleeve. Specifically, wedge-shaped or sheet-like air gaps are artificially created in the sample block to simulate localized cracks formed inside the core. The dimensions of the defect include crack length, depth, and width.

[0048] When the defect type is a bubble defect, an air domain is embedded in the sample block to form a defect sample block, which is then embedded during the fabrication of the defect sleeve. Specifically, a cylindrical or ellipsoidal air domain is embedded in the sample block to simulate a bubble defect formed inside the core. The dimensions of the defect include the diameter and height of the bubble.

[0049] When the defect type is electrode wrinkling, a sample block is embedded during the defect sleeve preparation process. Specifically, if electrode wrinkling is an electrode defect, the sample block is defect-free. This sample block is directly made of a material similar to the core material of the defect-free sleeve. A pit is formed in the core material in front of the electrode that needs wrinkling. The sample block is then used to press the electrode that needs wrinkling into the pit, thereby forming the electrode wrinkle. The dimensions of the defect are the length, width, and depth of the pit.

[0050] By preparing sample blocks based on defect type and defect parameters, high controllability of defect type, structure and size can be achieved. Specific parameters of defects can be flexibly designed according to different research needs and sleeve models, thereby achieving accurate and quantifiable simulation of defects.

[0051] Sub-step S42: Prepare the defective sleeve according to the defect parameters and manufacturing process, and embed the sample block during the preparation process.

[0052] Specifically, see Figure 3 The defective bushing includes: a conductive rod 1, a capacitor core 2, a mounting flange 3, and a skirt 4. A zero screen 5 is wound around the outside of the conductive rod 1. Multiple layers of core material, a first screen 6, multiple layers of core material, a second screen (sub-final screen) 7, multiple layers of core material, and a final screen 8 are sequentially wound around the outside of the zero screen 5, thus forming the capacitor core 2. A sample block 9 is embedded inside the capacitor core 2 according to the defect location. The first screen 6, the second screen (sub-final screen) 7, and the final screen 8 are all electrode plates. The connection relationships between the components in the defective bushing can be constructed according to the connection relationships of the components in existing dry-type capacitor bushings; this embodiment will not elaborate further.

[0053] During the preparation of the defective sleeve, according to the defect type, location and size determined in sub-step S41, a sample block is introduced during the winding of the capacitor core to simulate various defects.

[0054] When the defect type is any one of the following: metallic foreign object defect, insulating foreign object defect, local crack defect, or bubble defect, the defect bushing is prepared according to the manufacturing process of dry capacitor bushing. When rolling the capacitor core of the defect bushing, when the plate before the defect position is completed, the core material is rolled to the designed diameter. At the defect position, the core material is hollowed out to form a pit. The defect sample is placed in the pit, and the defect bushing is prepared according to the manufacturing process. Specifically, when preparing the defective sleeve, the existing manufacturing process is followed first. When the capacitor core 2 is rolled, it is rolled according to the normal rolling process. When rolling to the plate before the defect position, for example, when the defect position is between the second screen (secondary screen) 7 and the final screen 8, it is rolled to the second screen 7 according to the normal process. Then, multiple layers of core material are rolled to the designed diameter. According to the design requirements, the core material is hollowed out at the defect position to form a pit of the defect size. The prepared defect sample is placed in the pit. Then, the final screen 8 is rolled according to the design drawings and manufacturing process. Finally, the defective sleeve is prepared according to the manufacturing process.

[0055] When the defect type is plate wrinkling, when rolling the capacitor core of the defective sleeve, before the plate that needs wrinkling is reached, the core material at the corresponding defect location is hollowed out to form a pit. A sample block is used to press the plate that needs wrinkling into the pit, and then the core material is wound around. Then the defective sleeve is prepared according to the manufacturing process. Specifically, in preparing the defective bushing, the existing manufacturing process is followed first. When rolling the capacitor core 2, the normal rolling process is followed. When the core material before the required folding plate is reached, for example, when the plate folding is located at the second screen (secondary final screen) 7, the core material before the second screen 7 has already been rolled according to the normal process. Before rolling the second screen 7, according to the design requirements, at the defect location, a recess is formed by hollowing out part of the core material on the inner side before the second screen. A sample block is used to press the second screen 7 into the recess. Specifically, the second screen 7 is rolled according to the normal process, but at the recess, the sample block presses the second screen 7 into the recess. Then, the core material is rolled around the outside of the second screen 7 to fix the sample block in the recess. Subsequently, the final screen 8 is rolled according to the design drawings and manufacturing process, and the defective bushing is prepared according to the manufacturing process. In specific implementation, the sample block has sharp edges when pressing the plate that needs to be folded into the recess.

[0056] After the sample block is placed into the defective bushing, all capacitor cores containing defects must undergo subsequent treatments such as vacuum drying, impregnation, and curing according to standard procedures. In this way, by precisely controlling the introduction method and degree of defects, it can be ensured that the simulated defect state is highly consistent with the defect state formed in the actual dry capacitor bushing.

[0057] Step S1: Obtain the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, respectively.

[0058] Specifically, three-dimensional models of defective bushings and defect-free bushings are established respectively. Under the same voltage, the electric field distribution and radial electric field intensity of the capacitor core of the three-dimensional models of defective bushings and defect-free bushings are simulated and calculated respectively. The maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of defective bushings and defect-free bushings are obtained respectively.

[0059] More specifically, key dimensional parameters are obtained from the design drawings used to fabricate the defect-free sleeve. Then, a three-dimensional model of the defect-free sleeve is established using three-dimensional electromagnetic field simulation software based on these parameters. The dielectric property parameters of each material are then set in this three-dimensional model. These dielectric property parameters include dielectric constant, conductivity, and other parameters.

[0060] The key dimensional parameters are obtained from the design drawings used to fabricate the defective sleeve. Then, based on these key dimensional parameters and the defect parameters, a 3D electromagnetic field simulation software is used to create a 3D model of the defective sleeve. The dielectric property parameters of each material are then set within the 3D model of the defective sleeve. These dielectric property parameters include dielectric constant, conductivity, and other parameters.

[0061] The key dimensional parameters obtained from the design drawings include: the diameter and total length of the capacitor core; the diameter, length, and step length of each electrode layer; the thickness and number of insulating layers; and the position of the lead-out wires of the final screen.

[0062] The simulation calculations of electric field distribution and radial electric field intensity of capacitor core in the three-dimensional model of defective bushing and the simulation calculations of electric field distribution and radial electric field intensity of capacitor core in the three-dimensional model of defect-free bushing were both performed under the same voltage.

[0063] The electric field distribution of the defect-free bushing and the radial electric field intensity of the capacitor core are simulated and calculated to obtain the maximum electric field intensity and field intensity distribution characteristics.

[0064] Electric field simulation calculations were performed on the electric field distribution of the three-dimensional model of the defective bushing and the radial electric field intensity of the capacitor core to obtain the maximum electric field intensity and field strength distribution characteristics. The electric field distribution around the defect, the radial and axial electric field intensity curves of the capacitor core, and the location and range of the field strength concentration area were also obtained.

[0065] By comparing the results of electric field simulation calculations on the three-dimensional model of the defective bushing with the results of electric field simulation calculations on the three-dimensional model of the defect-free bushing, the analysis and research of bushing defects can be achieved.

[0066] Step S2: Obtain insulation performance test data for defective bushings and defect-free bushings respectively.

[0067] Specifically, a high-voltage testing platform is used to test the insulation performance of defective and defect-free bushings. The high-voltage testing platform includes: a power frequency high-voltage power supply system, a partial discharge detection system, an oscilloscope, a voltage divider, a high-voltage probe, a frequency domain dielectric spectrometer, and a shielded test chamber. In practice, the high-voltage testing platform can refer to the structure in existing technologies; this embodiment will not elaborate further.

[0068] During insulation performance testing, the bushing is installed on the test platform, reliably grounded, and connected to the power frequency high-voltage power supply system and the partial discharge detection system.

[0069] Whether testing the insulation performance of defective bushings or those without defects, the testing process is the same: A voltage ramp-up method is used, starting from 0V and ramping up at a preset rate. During the ramp-up process, the partial discharge signal of the bushing is continuously monitored, and the partial discharge initiation voltage (PDIV) is recorded. After ramping up to the rated operating voltage and stabilizing, the partial discharge quantity, discharge phase distribution (PRPD) spectrum, capacitance, dielectric loss factor, and frequency domain dielectric spectrum of the bushing are measured and recorded. Specifically, a frequency domain dielectric spectrometer is used to measure the bushing's capacitance, dielectric loss factor, and frequency domain dielectric spectrum.

[0070] In practice, the preset rate can be determined according to the actual situation, and this embodiment does not impose any restrictions on it.

[0071] Step S3 involves comparing and analyzing the maximum electric field strength, field strength distribution characteristics, and insulation performance test data of the defective bushing and the defect-free bushing in their three-dimensional models to establish a quantitative relationship between defect parameters and electrical insulation parameters.

[0072] Specifically, the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of defective and defect-free bushings, as well as the insulation performance test data of defective and defect-free bushings, are fitted together. Based on the fitted data, a quantitative relationship between defect parameters and electrical insulation parameters is established. The electrical insulation parameters include: maximum electric field strength, partial discharge initiation voltage, and partial discharge quantity.

[0073] More specifically, the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defect-free bushing in step S2, the electric field distribution around the defect, the radial and axial electric field strength curves of the capacitor core, the location and range of the field strength concentration area, and the partial discharge initiation voltage, partial discharge quantity, discharge phase distribution spectrum, bushing capacitance, dielectric loss factor and frequency domain dielectric spectrum of the defective bushing and the defect-free bushing in step S3 are compared and analyzed. At the same time, statistical analysis software is used to fit these associated datasets to establish a quantitative relationship between defect parameters (defect size, defect location) and key electrical insulation parameters such as maximum electric field strength, partial discharge initiation voltage, and partial discharge quantity.

[0074] By comparing the simulated maximum electric field strength of the same defect with the partial discharge initiation voltage data of the bushing obtained from insulation performance tests, it can be found that the higher the maximum electric field strength, the lower the partial discharge initiation voltage of the bushing.

[0075] By extracting useful information from the quantitative relationship between defect parameters and electrical insulation parameters to form an evaluation report, we can not only provide a theoretical basis for studying the formation and evolution of bushing defects, but also provide scientific basis and technical support for the safe production and operation and maintenance of dry-type capacitor bushings.

[0076] In this embodiment, the analysis and study of bushing defects can be initially realized by simulating the electric field of the three-dimensional models of the defective bushing and the three-dimensional models of the defect-free bushing. Then, the insulation performance of the defective bushing and the defect-free bushing can be tested to further verify the accuracy of the simulation results and ensure the accuracy and reliability of the simulation method.

[0077] Taking the simulation study of epoxy resin impregnated paper capacitor bushing and bubble defects as an example, the process of the epoxy resin impregnated paper capacitor bushing defect simulation method is introduced:

[0078] 1. Select an epoxy resin block with a composition similar to that of the epoxy-impregnated paper sleeve core material as the sample block. The dimensions of the epoxy resin sample block are designed as follows: diameter 3.3 mm, height 5.6 mm. The bubble size is: diameter 1 mm, height 3.5 mm, and the bubble is sealed inside the epoxy resin sample block. The epoxy resin sample block with bubble defects is placed inside the insulation layer between the second layer electrode (secondary screen) and the third layer electrode (final screen) of the capacitor core, at the symmetrical location of the lead wire of the sleeve's final screen.

[0079] 2. The ECAA-40.5 / 630-4 epoxy resin impregnated paper capacitor bushing was selected as the defect design platform. During the capacitor core winding process, normal winding procedures were followed. After winding the second layer of plates (secondary end screen), several layers of crepe paper (crepe paper is the core material of the epoxy resin impregnated paper capacitor bushing) were wound until the diameter reached 94.3mm. According to the design requirements, the axial length was measured. A 3.3mm diameter × 5.6mm height recess was created by hollowing out the crepe paper at the symmetrical location of the bushing's end screen lead-out line. The prepared epoxy resin sample with bubble defects was placed into this recess. The capacitor core winding was then completed according to the design drawings and manufacturing process.

[0080] 3. Using 3D electromagnetic field simulation software, establish 3D models of the defective bushing and the defect-free bushing, and perform simulation calculations on the overall electric field distribution and radial electric field intensity of the capacitor core in both models. (See also...) Figure 4 and Figure 5 Simulation results show that under a power frequency voltage of 40.5kV, the reference electric field strength in this region is about 3.18kV / mm when there is no defect. After introducing the defect, the maximum electric field strength (Emax) inside the bubble defect can reach 6.23kV / mm.

[0081] 4. Insulation performance tests were conducted on bushings containing bubble defects in a shielded laboratory (background <5 pC). The capacitance of the model was measured to be 595.5 pF, the dielectric loss factor to be 0.288%, and the partial discharge initiation voltage (PDIV) to be 18 kV. A typical discharge phase distribution (PRPD) spectrum was also obtained. (See attached image.) Figure 6 Meanwhile, no partial discharge signal was detected in the defect-free bushing at a power frequency voltage of 40.5kV.

[0082] 5. By cross-validating the experimental results and simulation results of the insulation performance test, it can be concluded that the presence of bubble defects causes a significant concentration of electric field strength inside the bushing core (increased simulated Emax), leading to a severe decline in insulation performance (a significant decrease in PDIV obtained from the experiment). This proves the effectiveness and accuracy of the defect simulation method. This result can provide a basis for quality control, strictly prevent the inclusion of bubble defects of this size, and provide an early warning reference. If similar discharge signals are detected, appropriate measures should be taken.

[0083] This embodiment proposes a scientific, systematic, and standardized method for simulating typical defects in dry-type capacitor bushings. It covers the entire process from defect design, physical preparation, simulation analysis, and experimental testing. By precisely controlling the defect type, defect size, and location, and combining 3D modeling, electric field simulation, and insulation performance testing, it provides technical means to obtain the influence of defects on the bushing's electric field distribution and the defect development law under operating conditions, supporting bushing insulation performance evaluation, fault diagnosis, and operation and maintenance.

[0084] This embodiment can establish quantifiable models of various bushing defects, using sample blocks to simulate various typical defects formed in dry capacitor bushings, including but not limited to internal bubbles, plate wrinkles, insulating / metallic foreign objects, and local cracks, forming an accurate and quantifiable defect model construction method. This allows for flexible extension to other types of defects or bushing models of different voltage levels, without relying on post-fault disassembly analysis, providing technical support for revealing the formation mechanism and evolution law of capacitor bushing core defects.

[0085] This embodiment establishes a precise, efficient, and controllable process for fabricating physical models of defective capacitor cores by incorporating simulated defects of specific types, sizes, and locations during the core rolling process. Through parametric simulation design and physical fabrication, the accuracy of the introduced defect types, sizes, and locations, as well as the consistency between different models, are ensured, resulting in highly repeatable defect research experiments.

[0086] This embodiment establishes a three-dimensional electric field simulation model including bushings with various typical defects. It systematically analyzes the influence of changes in parameters such as defect size and location on the maximum electric field intensity and distribution of the bushing, revealing the electric field distortion characteristics of different defects. This allows for preliminary prediction of the severity of unknown defects through simulation, improving the sensitivity and accuracy of defect diagnosis. Simultaneously, it measures insulation performance parameters such as frequency domain dielectric spectrum and partial discharge of the defective bushing. Comparative analysis of simulation results and insulation performance test data ensures the accuracy and reliability of the simulation method, providing data support for bushing insulation status assessment and fault early warning.

[0087] Device Example:

[0088] See Figure 7 This embodiment also proposes a dry-type capacitor bushing defect simulation device, which includes: an electric field acquisition unit 100, a test data acquisition unit 200, and an analysis unit 300. The electric field acquisition unit 100 is used to acquire the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, respectively. The test data acquisition unit 200 is used to acquire the insulation performance test data of the defective bushing and the defect-free bushing, respectively. The analysis unit 300 is used to compare and analyze the maximum electric field intensity, field intensity distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, to establish a quantitative relationship between defect parameters and electrical insulation parameters.

[0089] The field strength acquisition unit 100 is also used to establish three-dimensional models of the defective bushing and the defect-free bushing, respectively, and to simulate and calculate the electric field distribution and radial electric field strength of the capacitor core of the three-dimensional models of the defective bushing and the defect-free bushing under the same voltage, respectively, and to obtain the maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing, respectively; when performing electric field simulation calculations on the three-dimensional model of the defective bushing, it also obtains the electric field distribution around the defect, the radial and axial electric field strength curves of the capacitor core, and the location and range of the field strength concentration area.

[0090] The test data acquisition unit 200 is also used to perform insulation performance tests on defective bushings and defect-free bushings respectively. During the test, starting from 0V, the voltage is increased at a preset rate. During the voltage increase, the partial discharge signal of the bushing is continuously monitored and the partial discharge initiation voltage of the bushing is recorded. After the voltage is increased to the rated operating voltage and stabilized, the partial discharge quantity, discharge phase distribution spectrum, capacitance, dielectric loss factor and frequency domain dielectric spectrum of the bushing are measured and recorded.

[0091] The analysis unit 300 is also used to fit the maximum electric field strength and field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, and to establish a quantitative relationship between defect parameters and electrical insulation parameters based on the fitted data; wherein, the electrical insulation parameters include: maximum electric field strength, partial discharge initiation voltage and partial discharge quantity.

[0092] Since the dry-type capacitor bushing defect simulation method has the above-mentioned effects, the dry-type capacitor bushing defect simulation device also has the corresponding technical effects.

[0093] It should be noted that the dry capacitor bushing defect simulation method and device in this invention are based on the same principle, and related parts can be referred to each other.

[0094] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0095] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0096] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for simulating defects in dry-type capacitor bushings, characterized in that, Includes the following steps: The maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing were obtained respectively. Insulation performance test data of the defective bushing and the defect-free bushing were obtained respectively; The maximum electric field strength, field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, are compared and analyzed to establish a quantitative relationship between defect parameters and electrical insulation parameters.

2. The method for simulating defects in dry-type capacitor bushings according to claim 1, characterized in that, Before the steps of obtaining the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of the defective bushing and the defect-free bushing respectively, the method further includes: Determine the defect type and defect parameters, and prepare the defect sleeve.

3. The method for simulating defects in dry-type capacitor bushings according to claim 2, characterized in that, The defect types include one or more of the following: metallic foreign matter defects, insulating foreign matter defects, localized crack defects, bubble defects, or electrode wrinkles. The defect parameters include the location and size of the defect.

4. The method for simulating defects in dry-type capacitor bushings according to claim 3, characterized in that, In the steps of determining the defect type and defect parameters, and preparing the defective sleeve... Prepare a sample block according to the defect type and the defect parameters; According to the aforementioned defect parameters and manufacturing process, a defective sleeve is prepared, and the sample block is embedded during the preparation process.

5. The method for simulating defects in dry-type capacitor bushings according to claim 4, characterized in that, In the step of preparing the sample block according to the defect type and the defect parameters Select a sample block that is similar to the material of the defect-free sleeve core; When the defect type is a metallic foreign object defect, a metallic foreign object is placed in the sample block to form a defective sample block, and the defective sample block is embedded in the defective sleeve preparation process. When the defect type is an insulating foreign object defect, an insulating foreign object is placed in the sample block to form a defect sample block, and the defect sample block is embedded in the defect sleeve preparation process. When the defect type is a local crack defect, an air gap is created in the sample block to form a defect sample block, and the defect sample block is embedded in the defect sleeve preparation process; When the defect type is a bubble defect, an air domain is embedded in the sample block to form a defect sample block, and the defect sample block is embedded during the preparation of the defect sleeve. When the defect type is electrode folds, the sample block is embedded during the preparation of the defect sleeve.

6. The method for simulating defects in dry-type capacitor bushings according to claim 5, characterized in that, The step of preparing the defective sleeve according to the defect parameters and manufacturing process, and embedding the sample block during the preparation process. When the defect type is any one of metallic foreign object defect, insulating foreign object defect, local crack defect, or bubble defect, when rolling the capacitor core of the defective sleeve, when the plate before the defect position is completed, the core material is rolled to the designed diameter, the core material is hollowed out at the defect position to form a pit, the defective sample is placed in the pit, and the defective sleeve is prepared according to the manufacturing process. When the defect type is plate wrinkling, when rolling the capacitor core of the defective sleeve, before the plate that needs wrinkling is reached, the core material at the corresponding defect location is hollowed out to form a pit. The sample block is used to press the plate that needs wrinkling into the pit, and then the core material is wound around. The defective sleeve is then prepared according to the manufacturing process.

7. The method for simulating defects in dry-type capacitor bushings according to claim 2, characterized in that, In the steps of obtaining the maximum electric field intensity and field intensity distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing respectively, Three-dimensional models of defective bushings and defect-free bushings are established respectively. Under the same voltage, the electric field distribution and radial electric field intensity of the capacitor core of the three-dimensional models of defective bushings and defect-free bushings are simulated and calculated respectively. The maximum electric field intensity and field intensity distribution characteristics of the three-dimensional models of defective bushings and defect-free bushings are obtained respectively. When performing electric field simulation calculations on the three-dimensional model of the defective bushing, the electric field distribution around the defect, the radial and axial electric field intensity curves of the capacitor core, and the location and range of the field intensity concentration area are also obtained.

8. The method for simulating defects in dry-type capacitor bushings according to claim 1, characterized in that, In the step of obtaining the insulation performance test data of the defective bushing and the defect-free bushing respectively, Insulation performance tests were performed on the defective bushing and the defect-free bushing respectively. During the test, the voltage was increased from 0V at a preset rate. The partial discharge signal of the bushing was continuously monitored during the voltage increase process, and the partial discharge initiation voltage of the bushing was recorded. After the voltage is boosted to the rated operating voltage and stabilized, the partial discharge quantity, discharge phase distribution spectrum, capacitance, dielectric loss factor and frequency domain dielectric spectrum of the bushing are measured and recorded.

9. The method for simulating defects in dry-type capacitor bushings according to claim 1, characterized in that, In the step of comparing and analyzing the maximum electric field strength, field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, to establish a quantitative relationship between defect parameters and electrical insulation parameters, The maximum electric field strength and field strength distribution characteristics of the three-dimensional models of the defective bushing and the three-dimensional models of the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, are fitted together. A quantitative relationship between defect parameters and electrical insulation parameters is established based on the fitted data. The electrical insulation parameters include: maximum electric field strength, partial discharge initiation voltage, and partial discharge quantity.

10. A dry-type capacitor-type bushing defect simulation device, characterized in that, include: The field strength acquisition unit (100) is used to acquire the maximum electric field strength and field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, respectively. The test data acquisition unit (200) is used to acquire the insulation performance test data of the defective bushing and the defect-free bushing, respectively; The analysis unit (300) is used to compare and analyze the maximum electric field strength, field strength distribution characteristics of the three-dimensional model of the defective bushing and the three-dimensional model of the defect-free bushing, as well as the insulation performance test data of the defective bushing and the defect-free bushing, and to establish a quantitative relationship between defect parameters and electrical insulation parameters.

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