Method for detecting damp defect of dry type bushing capacitor core body based on dielectric property

Abstract

The invention discloses a dielectric property-based dry-type bushing capacitor core damp defect detection method, and aims to improve the accuracy and sensitivity of dry-type bushing capacitor core damp detection. According to the method, a frequency domain dielectric response test platform composed of a DIRANA dielectric response analyzer, a high and low temperature test box and a computer is built to carry out frequency domain dielectric response test on a core body. The core is to monitor the change of the dielectric loss factor (tan delta) of the core body in a low-frequency band (0.001 Hz to 0.1 Hz) under different wetting modes and degrees. Experiments show that the method shows high sensitivity in early-stage damp detection, and compared with a traditional power frequency detection method, the method can find the damp defect of the core body earlier. According to the invention, an efficient and reliable technical means is provided for damp assessment of the dry bushing capacitor core body, and the operation and maintenance level and safety of power equipment are improved.

Description

Technical Field

[0001] The invention relates to the technical field of power equipment and state monitoring, and in particular to a method for detecting moisture defects of a dry-type bushing capacitor core based on dielectric properties. Background Art

[0002] As an indispensable insulating device in the power system, the insulation performance of the dry-type bushing capacitor core is directly related to the safe and stable operation of high-voltage equipment. In practical applications, the dry-type bushing capacitor core is mostly made of epoxy impregnated paper material. However, this material is susceptible to moisture during long-term operation, resulting in a significant decrease in its insulation performance, increasing the risk of partial discharge and insulation breakdown, and thus affecting the safety and reliability of the entire power system.

[0003] Existing methods for detecting moisture defects in dry bushings mainly include offline measurement of insulation resistance, power frequency dielectric loss (tanδ) and partial discharge. Although these methods can detect defects in dry bushings to a certain extent, they have many limitations. For example, although offline measurement of insulation resistance and power frequency tanδ can reflect the insulation condition, there are problems of long detection cycle and poor real-time performance. Especially in the early stage of moisture, these methods often have difficulty in capturing subtle changes in insulation performance; partial discharge detection usually requires offline detection at a higher voltage, which can easily pose a potential threat to equipment safety, and is not sensitive to slight moisture inside the core, making it difficult to meet the needs of modern power systems for real-time monitoring and rapid diagnosis of equipment.

[0004] In recent years, the frequency domain dielectric response technology has attracted much attention due to its sensitivity to material microstructure and moisture defects. This technology can reveal information such as the moisture content and moisture degree inside the material by measuring the dielectric properties of the material at different frequencies. However, the application of frequency domain dielectric response technology in the detection of moisture defects in dry casing is still in its infancy, especially for the detection effect of moisture on the crepe paper inside the real glue impregnated paper core and natural moisture in the air, which needs further research.

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] In practical applications, insulation resistance, power frequency dielectric loss and partial discharge are limited by offline measurement and cannot well reflect the slow aging of insulation or slight moisture. Although the existing methods can detect the defects of dry bushings to a certain extent, they have the problems of long detection cycle, poor real-time performance and low detection accuracy, which makes it difficult to meet the needs of modern power systems for real-time monitoring and rapid diagnosis of equipment.

[0007] In view of the above background, the present invention proposes a method for detecting moisture defects in the core of a dry-type bushing capacitor based on dielectric properties, aiming to address the shortcomings of the existing technology, achieve efficient and accurate detection of moisture defects in the core of a dry-type bushing capacitor, and ensure the safe and stable operation of the power system. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a method for detecting moisture defects in a dry-type bushing capacitor core based on dielectric properties.

[0009] The present invention is implemented as follows: a method for detecting moisture defects in a dry-type bushing capacitor core based on dielectric properties, comprising the following steps:

[0010] Step 1: Build a frequency domain dielectric response test platform for the dry-type bushing capacitor core, which includes a dielectric response analyzer, a high and low temperature test chamber, and a computer;

[0011] Step 2: Simulate the natural working conditions to cause moisture intrusion from the air due to the shedding of insulating paint on the glue-impregnated paper core;

[0012] Step 3: Place the core to be tested in a high and low temperature test chamber, set the preset temperature, and use a dielectric response analyzer to perform a frequency domain dielectric response test in the low frequency band (0.001Hz to 0.1Hz);

[0013] Step 4: Analyze the dielectric characteristic curve obtained from the test, extract the dielectric loss factor (tanδ) value at the characteristic frequency point (such as 0.046Hz, 1Hz), and compare it with the data under normal state or known moisture state;

[0014] Step 5: Evaluate the moisture level of the dry-type bushing capacitor core based on the variation of tanδ value.

[0015] Further, the step 2 specifically includes:

[0016] (1) Use sandpaper to polish the insulating paint on the axial end surface of the glue-impregnated paper core until the internal crepe paper is exposed to the air to ensure that the moisture in the atmosphere is in full contact with the crepe paper;

[0017] (2) hanging the glue-impregnated paper core in the air, maintaining the ambient temperature at 20° C. to 25° C. and the relative humidity at 60% to 70%, and subjecting the glue-impregnated paper core to moisture treatment;

[0018] (3) After a period of moisture treatment, the frequency domain dielectric response test of the glue-impregnated paper core was carried out to compare the changes in the frequency domain dielectric properties under different moisture treatment times.

[0019] Furthermore, in step 2, the degree of dryness of the crepe paper in the core is controlled to include five different moisture states: completely dry, dried for 48 hours, dried for 24 hours, not dried at all, and humidified.

[0020] Furthermore, the dielectric response analyzer used in step 3 is DIRANA, which can

[0021] The test is carried out in the frequency range of 100 to 5 kHz, and the test data are collected and processed by computer.

[0022] Furthermore, the characteristic frequency points extracted in step 4 include those with significant dielectric loss changes in the low frequency band.

[0023] 0.001Hz, 0.01Hz and 0.046Hz, as well as the representative 1Hz in the mid-to-low frequency band.

[0024] Furthermore, the method for evaluating the degree of moisture in step 5 includes establishing an empirical formula between the tanδ value and the moisture exposure time, performing curve fitting, and verifying the accuracy of the evaluation method through the goodness of fit.

[0025] Furthermore, the empirical formula shows that at the characteristic frequency point in the low frequency band (such as 1 Hz), the tanδ value shows a significant and monotonically increasing trend with the extension of moisture exposure time, and the goodness of fit is as high as 0.98.

[0026] Another object of the present invention is to provide a dry-type bushing capacitor core moisture defect detection system based on dielectric properties for implementing the detection method, comprising:

[0027] A dielectric response test unit, used to perform dielectric characteristic testing within a preset frequency range using a dielectric response analyzer;

[0028] A data processing unit is used to collect and process test data and extract the tanδ value of characteristic frequency points;

[0029] An evaluation unit, used to evaluate the moisture content of the core according to the variation law of tanδ value;

[0030] Temperature control unit, used to set and maintain preset temperature in high and low temperature test chamber to ensure the accuracy of test results.

[0031] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, characterized in that when the computer program is executed by a processor, it can implement the dry-type bushing capacitor core moisture defect detection method based on dielectric properties.

[0032] Another object of the present invention is to provide a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the dry-type bushing capacitor core moisture defect detection method based on dielectric properties.

[0033] Another object of the present invention is to provide an information data processing terminal, which includes the dry-type bushing capacitor core moisture defect detection system based on dielectric properties.

[0034] In combination with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solutions to be protected by the present invention from the following aspects:

[0035] First, in view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, the technical solutions to be protected by the present invention and the results and data during the research and development process are closely combined to analyze in detail and deeply how the technical solutions of the present invention solve the technical problems, and some creative technical effects brought about after solving the problems. The specific description is as follows:

[0036] The method of the present invention conducts a frequency domain dielectric response test on the core by building a frequency domain dielectric response test platform composed of a DIRANA dielectric response analyzer, a high and low temperature test chamber and a computer. The core is to monitor the changes in the dielectric loss factor (tanδ) of the core in the low frequency band (0.001Hz to 0.1Hz) under different moisture modes and degrees. Experiments show that this method exhibits high sensitivity when detecting initial moisture, and can detect moisture defects in the core earlier than traditional power frequency detection methods. The present invention provides an efficient and reliable technical means for moisture assessment of the dry bushing capacitor core, which helps to improve the operation and maintenance level and safety of power equipment.

[0037] Second, the technical solution of the present invention effectively solves the problem in the prior art that it is difficult to accurately detect the moisture state of the capacitor core through an innovative dry-type bushing capacitor core moisture defect detection method. In traditional detection methods, it is often necessary to rely on measurements in higher frequency bands or judge the state of the capacitor core only through external observation. These methods not only lack precision, but also have the risk of being interfered by the environment. By introducing frequency domain dielectric response testing and low-frequency dielectric loss factor analysis, the present invention can more sensitively capture the slight changes caused by moisture in the capacitor core, significantly improving the sensitivity and accuracy of detection.

[0038] In addition, the present invention also realizes the quantitative evaluation of the moisture degree of the dry-type bushing capacitor core, overcoming the limitation of only being able to perform qualitative analysis in the prior art. This progress is of great significance in industrial applications, especially in the operation and maintenance of power equipment. The method of the present invention can timely discover the moisture problem of the capacitor core, take measures in advance to avoid the occurrence of failures, thereby greatly improving the safety and reliability of the power system.

[0039] The more significant technical progress is that the present invention adopts a frequency domain dielectric response test method, which can not only obtain accurate dielectric characteristic curves in a wide frequency range, but also accurately distinguish different degrees of moisture conditions by extracting the tanδ value of characteristic frequency points. This innovative detection technology can adapt to a variety of application scenarios, especially in power equipment that requires high-precision detection, showing excellent applicability and practical value.

[0040] Through these technological innovations and advances, the present invention provides a more reliable and efficient solution for the maintenance and monitoring of power equipment in industrial applications, and promotes technological upgrading and improvement of safety assurance levels in the power industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of a method for detecting moisture defects in a dry-type bushing capacitor core based on dielectric properties provided by an embodiment of the present invention;

[0042] Figure 2 It is a structural diagram of a dry-type bushing capacitor core moisture defect detection system based on dielectric properties provided by an embodiment of the present invention;

[0043] Figure 3 is a frequency domain dielectric spectrum test principle diagram provided by an embodiment of the present invention;

[0044] Figure 4 The following are the actual pictures of the glue-impregnated paper core winding provided by the embodiment of the present invention; (a) the core winding process, (b) the actual glue-impregnated paper core;

[0045] Figure 5 is a schematic diagram of a DIRANA dielectric response analyzer provided in an embodiment of the present invention;

[0046] Figure 6 Schematic diagram of the wiring of the frequency domain dielectric response test platform provided by an embodiment of the present invention; (a) overall wiring schematic diagram, (b) actual shot of on-site wiring;

[0047] Figure 7 is a tanδ-f curve diagram of a dry core at different moisture levels at 30°C provided by an embodiment of the present invention;

[0048] Figure 8This is a comparison diagram of tanδ at 0.001Hz, 0.01Hz and 50Hz of a dry core provided by an embodiment of the present invention;

[0049] Fig. 9 : is a frequency domain curve diagram of the complex capacitance of the core body at different moisture levels at 30° C. provided by an embodiment of the present invention; (a) the real part of the complex capacitance C′; (b) the imaginary part of the complex capacitance C″;

[0050] Fig.10 : is a frequency domain curve diagram of the complex dielectric constant of the core at different moisture levels at 30°C provided by an embodiment of the present invention; (a) the real part ε′ of the complex dielectric constant; (b) the imaginary part ε″ of the complex dielectric constant;

[0051] Fig.11 : is a Cf curve diagram under different moisture exposure time provided by an embodiment of the present invention; (a) complex capacitance real part C'-f curve; (b) complex capacitance imaginary part C"-f curve;

[0052] Fig.12 is a frequency domain dielectric response curve of the core under natural moisture in air provided by an embodiment of the present invention;

[0053] Fig.13 : is a power frequency dielectric loss curve diagram of a core body under different moisture exposure time in air provided by an embodiment of the present invention;

[0054] Fig.14 : is a dielectric loss value curve diagram at a characteristic frequency point of 1 Hz under different moisture exposure time provided by an embodiment of the present invention;

[0055] Fig.15 It is a fitting curve diagram of dielectric loss value and natural moisture exposure time provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0057] like Figure 1 As shown, a method for detecting moisture defects of a dry-type bushing capacitor core based on dielectric properties is provided in an embodiment of the present invention, comprising the following steps:

[0058] Step 1: Build a frequency domain dielectric response test platform for the dry-type bushing capacitor core, which includes a dielectric response analyzer, a high and low temperature test chamber, and a computer;

[0059] Step 2: Simulate the natural working conditions to cause moisture intrusion from the air due to the shedding of insulating paint on the glue-impregnated paper core;

[0060] Step 3: Place the core to be tested in a high and low temperature test chamber, set the preset temperature, and use a dielectric response analyzer to perform a frequency domain dielectric response test in the low frequency band (0.001Hz to 0.1Hz);

[0061] Step 4: Analyze the dielectric characteristic curve obtained from the test, extract the dielectric loss factor (tanδ) value at the characteristic frequency point (such as 0.046Hz, 1Hz), and compare it with the data under normal state or known moisture state;

[0062] Step 5: According to the variation law of tanδ value, evaluate the moisture degree of dry-type bushing capacitor core. This method first requires the construction of a platform specifically for the frequency domain dielectric response test of dry-type bushing capacitor core. The platform includes a dielectric response analyzer, a high and low temperature test chamber, and a computer. The dielectric response analyzer is used to measure the dielectric properties of the capacitor core at different frequencies, and the high and low temperature test chamber is used to control the temperature of the test environment and simulate the moisture state of the capacitor core under different temperature conditions. The computer is used to collect, store and process the test data.

[0063] In order to evaluate the changes in the dielectric properties of capacitor cores under different moisture levels, this method simulates the intrusion of moisture from the air caused by the shedding of insulating paint on the resin-impregnated paper core under natural working conditions, and can generate a series of capacitor core samples with known moisture states for subsequent testing and analysis. The moisture level of these samples will affect their dielectric properties, especially the dielectric loss factor in the low-frequency band.

[0064] The details of the water intrusion in the air caused by the shedding of insulating paint on the glue-impregnated paper core under simulated natural working conditions are as follows:

[0065] (1) Use sandpaper to polish the insulating paint on the axial end surface of the glue-impregnated paper core until the internal crepe paper is exposed to the air to ensure that the moisture in the atmosphere is in full contact with the crepe paper;

[0066] (2) hanging the glue-impregnated paper core in the air, maintaining the ambient temperature at 20° C. to 25° C. and the relative humidity at 60% to 70%, and subjecting the glue-impregnated paper core to moisture treatment;

[0067] After a period of moisture treatment, the frequency domain dielectric response test was carried out on the glue-impregnated paper core to explore and compare the changes in frequency domain dielectric properties under different moisture exposure time.

[0068] Place the prepared capacitor core in a high and low temperature test chamber and set the preset test temperature to ensure the stability of the test conditions. Use a dielectric response analyzer to perform frequency domain dielectric response testing in the low frequency band of 0.001Hz to 0.1Hz. In this frequency range, the dielectric properties of the capacitor core are particularly sensitive to its internal water content or moisture level. The dielectric characteristic curve obtained from the test can intuitively reflect the response of the core at different frequencies.

[0069] By analyzing the dielectric characteristic curves obtained from the test, the dielectric loss factor tanδ values ​​at characteristic frequency points (such as 0.046Hz, 1Hz) are extracted. By comparing these tanδ values ​​with reference data under normal conditions or known moisture conditions, it can be clearly seen that the tanδ value changes with the increase in moisture. According to the changing trend of the tanδ value, this method can accurately evaluate the moisture content of the dry-type bushing capacitor core, thus providing a scientific basis for maintenance decisions.

[0070] Furthermore, in step 2, the degree of dryness of the crepe paper in the core is controlled to include five different moisture states: completely dry, dried for 48 hours, dried for 24 hours, not dried at all, and humidified.

[0071] Furthermore, the dielectric response analyzer used in step 3 is DIRANA, which can

[0072] The test is carried out in the frequency range of 100 to 5 kHz, and the test data are collected and processed by computer.

[0073] Furthermore, the characteristic frequency points extracted in step 4 include those with significant dielectric loss changes in the low frequency band.

[0074] 0.001Hz, 0.01Hz and 0.046Hz, as well as the representative 1Hz in the mid-to-low frequency band.

[0075] Furthermore, the method for evaluating the degree of moisture in step 5 includes establishing an empirical formula between the tanδ value and the moisture exposure time, performing curve fitting, and verifying the accuracy of the evaluation method through the goodness of fit.

[0076] Furthermore, the empirical formula shows that at the characteristic frequency point in the low frequency band (such as 1 Hz), the tanδ value shows a significant and monotonically increasing trend with the extension of moisture exposure time, and the goodness of fit is as high as 0.98.

[0077] like Figure 2 As shown, an embodiment of the present invention provides a dry-type bushing capacitor core moisture defect detection system based on dielectric properties that implements the detection method as described above, including:

[0078] A dielectric response test unit, used to perform dielectric characteristic testing within a preset frequency range using a dielectric response analyzer;

[0079] A data processing unit is used to collect and process test data and extract the tanδ value of characteristic frequency points;

[0080] An evaluation unit, used to evaluate the moisture content of the core according to the variation law of tanδ value;

[0081] Temperature control unit, used to set and maintain preset temperature in high and low temperature test chamber to ensure the accuracy of test results.

[0082] Figure 3 It is a frequency domain dielectric spectrum test principle diagram provided by an embodiment of the present invention; conventional power frequency complex capacitance and dielectric loss measurement are extended to low frequency and high frequency bands (such as 0.1mHz to 1kHz).

[0083] Figure 4 It is a winding diagram of a glue-impregnated paper core provided by an embodiment of the present invention and a physical diagram; Figure 4 (a) shows the core winding process. During the core rolling process, the crepe paper interlayer of core No. 4 is evenly humidified, and the rolling process of other cores is normal. After the crepe paper cores are rolled, they are uniformly placed in an environment with a temperature of 25℃±1℃ and a relative humidity of 70-80% for 72 hours. After cores No. 2 and No. 3 are dried at 50℃ for a preset time, all cores are loaded with tooling, epoxy poured, cured and cooled to obtain finished cores. Figure 4 (a) is the finished product picture.

[0084] Figure 5 It is a schematic diagram of the DIRANA dielectric response analyzer provided in an embodiment of the present invention; the instrument can perform frequency domain dielectric response tests with a maximum voltage peak of 200V and a frequency bandwidth of 1mHz to 5kHz, and can simultaneously perform frequency domain dielectric response tests on two test samples through two channels, and a computer is required for use.

[0085] Figure 6 It is a wiring diagram of a frequency domain dielectric response test platform provided by an embodiment of the present invention; Figure 6 (a) The high voltage lead is led out from the output end of DIRANA, enters the high and low temperature test chamber cavity and is connected to the high voltage loading end of the core, and the input end is connected to the end screen lead of the core. The experimental temperature is set through the high and low temperature test chamber, and the data obtained from the frequency domain dielectric response instrument test is collected and processed by a computer. The actual wiring is as follows Figure 6 (b) as shown.

[0086] Figure 7 is a tanδ-f curve diagram of a dry core at different moisture levels at 30°C provided by an embodiment of the present invention;

[0087] The results show that in the low-frequency region, as the moisture content inside the core increases, the dielectric loss increases significantly; in the high-frequency region, although the increase in moisture content causes the number of dipoles to increase, the dipoles cannot respond quickly to changes in the high-frequency electric field, resulting in a decrease in the contribution of dielectric loss caused by their polarization, and the curve gradually converges.

[0088] Figure 8 This is a comparison chart of tanδ at 0.001Hz, 0.01Hz and 50Hz of the dry core provided by the embodiment of the present invention; the degree of moisture in the core is from high to low: 4-1-2-3-5, which is consistent with the arrangement order of the horizontal axis. The power frequency dielectric loss value cannot timely reflect the moisture defect of the dry bushing core, while the characteristic frequencies of 0.001Hz and 0.01Hz obtained by the dielectric spectrum curve can detect the moisture of the dry core early, thereby avoiding the serious deterioration of the main insulation of the dry core due to moisture.

[0089] Fig. 9 is a frequency domain curve diagram of core complex capacitance at different moisture levels at 30° C. provided by an embodiment of the present invention;

[0090] (a) Real part of complex capacitance C′; (b) Imaginary part of complex capacitance C″; Fig.10 : is a frequency domain curve diagram of the complex dielectric constant of the core at different moisture levels at 30°C provided by an embodiment of the present invention; (a) the real part of the complex dielectric constant ε′; (b) the imaginary part of the complex dielectric constant ε″; Fig. 9 (a) It can be seen that when the frequency is higher than 0.1Hz, the real part of the complex capacitance C' of the dry bushing changes relatively slowly with the frequency, and after the frequency is lower than 0.1Hz, the real part of the complex capacitance begins to increase. As the time of exposure to moisture increases, the capacitance of the bushing gradually increases, especially in the low-frequency range. In general, as the degree of moisture increases, the frequency response curve of the real part of the complex capacitance C' of the bushing moves toward the high-frequency direction. As the degree of moisture in the bushing increases, the increase in dielectric conductivity loss and polarization loss causes the imaginary part of the complex capacitance C" to increase accordingly, as shown in Fig. 9 (b) Comparing the curves of C′ and tanδ with frequency, it can be found that they have similar changing rules.

[0091] Fig.11 is a Cf curve diagram under different moisture exposure time provided by an embodiment of the present invention; the frequency domain response curve of the real part C' of the core complex capacitance under different natural moisture exposure time is as follows Fig.11 (a) is shown. After the core is completely dried, C' is almost a horizontal straight line in the frequency domain. As the natural moisture exposure time increases, C' in the low-frequency section begins to increase gradually. After the moisture exposure time reaches 66h, the slope of the curve in the low-frequency section becomes smaller and gradually flat, and the baseline shift begins to appear from 90h. The frequency domain response curves of the imaginary part of the complex capacitance C" of the core under different natural moisture exposure times are shown in Fig.11As shown in (b), as the degree of moisture increases, the curve shows an increasing trend in the overall frequency domain. After the moisture exposure time reaches 56 hours, the C"-f curve begins to show a baseline shift, and a peak appears in the 0.01Hz~1Hz frequency band.

[0092] Fig.12 This is a frequency domain dielectric response curve of the core under natural moisture in air provided by an embodiment of the present invention; in general, as the moisture degree of the dry core increases, the dielectric loss value of the dry core increases in the low frequency section.

[0093] (0.001Hz~0.1Hz) shows a trend of increasing continuously in the initial stage, then a peak appears and continuously moves to the right; in the medium frequency section (0.1Hz~100Hz), it increases successively with the increase of the length of time it is naturally moistened in the air; in the high frequency section (100Hz~5000Hz), the curve gradually converges into a cluster.

[0094] Fig.13 It is a power frequency dielectric loss curve of the core under different moisture exposure time in the air provided by the embodiment of the present invention; the results show that in the initial stage of moisture exposure (0 to 12 hours), the dielectric loss value remains almost constant, which is difficult to accurately reflect the actual moisture condition of the core. As the moisture exposure time increases, the dielectric loss value gradually increases, but the growth trend is gentle, until it reaches a certain critical point (such as 45 hours), the dielectric loss value increases rapidly, and the power frequency dielectric loss is 0.0581 at 90 hours, compared with 0.00385 at 6 hours of moisture exposure, the increase is 1509%; compared with 0.01284 at 36 hours of moisture exposure, the critical point of rapid increase in dielectric loss value, the increase is 452.5%; but the increase in dielectric loss value of 36 hours is smaller than that of the core that has not been dampened. This hysteresis may not only lead to misjudgment and missed judgment, but also may cause potential moisture defects to not be discovered in time, thereby causing more serious safety accidents.

[0095] Fig.14 It is a dielectric loss value curve at the characteristic frequency point 1Hz under different moisture exposure time provided by an embodiment of the present invention; the results show that the dielectric loss value at this frequency point presents a more sensitive and monotonically increasing trend with the extension of moisture exposure time. Compared with the dielectric loss value at other frequency points, the curve is not monotonous and the difference is too small. This discovery provides a new perspective and tool for accurately evaluating the natural moisture degree of the core.

[0096] Fig.15 This is a fitting curve diagram of dielectric loss value and natural dampening time provided by an embodiment of the present invention; the results show that the goodness of the measured dielectric loss value under different dampening time and the fitting curve reaches 0.98, indicating that there is good consistency between the measured value and the fitting curve. This result not only proves the effectiveness of the method, but also provides strong support for its practical application in dry core dampening defect diagnosis.

[0097] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated hardware. A person skilled in the art will understand that the above-mentioned devices and methods can be implemented using computer executable instructions and / or

[0098] Or included in a processor control code, for example, such code is provided on a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above hardware circuits and software, such as firmware.

[0099] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting moisture defects in a dry-type bushing capacitor core based on dielectric properties, characterized in that: The following steps are involved: Step 1: Build a frequency domain dielectric response test platform for the dry-type bushing capacitor core, which includes a dielectric response analyzer, a high and low temperature test chamber, and a computer; Step 2: Simulate the natural working conditions to cause moisture intrusion from the air due to the shedding of insulating paint on the glue-impregnated paper core; Step 3: Place the core to be tested in a high and low temperature test chamber, set the preset temperature, and use a dielectric response analyzer to perform a frequency domain dielectric response test in the low frequency band; the low frequency band is 0.001Hz to 0.1Hz; Step 4: Analyze the dielectric characteristic curve obtained from the test, extract the dielectric loss factor tanδ value at the characteristic frequency point, and compare it with the data under normal state or known moisture state; Step 5: Evaluate the moisture level of the dry-type bushing capacitor core based on the variation of tanδ value.

2. The detection method according to claim 1, characterized in that The step 2 specifically includes: (1) Use sandpaper to polish the insulating paint on the axial end surface of the glue-impregnated paper core until the internal crepe paper is exposed to the air to ensure that the moisture in the atmosphere is in full contact with the crepe paper; (2) hanging the glue-impregnated paper core in the air, maintaining the ambient temperature at 20° C. to 25° C. and the relative humidity at 60% to 70%, and subjecting the glue-impregnated paper core to moisture treatment; (3) After a period of moisture treatment, the frequency domain dielectric response test of the glue-impregnated paper core was carried out to compare the changes in the frequency domain dielectric properties under different moisture treatment times.

3. The detection method according to claim 1, characterized in that The dielectric response analyzer used in step three is DIRANA, which can perform tests in the frequency range of 1 mHz to 5 kHz, and collect and process test data through a computer.

4. The detection method according to claim 1, characterized in that The characteristic frequency points extracted in step 4 include 0.001 Hz, 0.01 Hz and 0.046 Hz where the dielectric loss changes significantly in the low frequency band, and 1 Hz which is representative of the low and medium frequency bands.

5. The detection method according to claim 1, characterized in that The method for evaluating the degree of moisture in step 5 includes establishing an empirical formula between the tanδ value and the moisture exposure time, performing curve fitting, and verifying the accuracy of the evaluation method through the goodness of fit.

6. The detection method according to claim 5, characterized in that The empirical formula shows that at the characteristic frequency point in the low frequency band, the tanδ value shows a significant and monotonically increasing trend with the extension of moisture exposure time, and the goodness of fit is as high as 0.

98.

7. A dry-type bushing capacitor core moisture defect detection system based on dielectric properties implementing the detection method according to any one of claims 1 to 6, characterized in that: include: A dielectric response test unit, used to perform dielectric characteristic testing within a preset frequency range using a dielectric response analyzer; A data processing unit is used to collect and process test data and extract the tanδ value of characteristic frequency points; An evaluation unit, used to evaluate the moisture content of the core according to the variation law of tanδ value; Temperature control unit, used to set and maintain preset temperature in high and low temperature test chamber to ensure the accuracy of test results.

8. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it can implement the dry-type bushing capacitor core moisture defect detection method based on dielectric properties as described in any one of claims 1 to 6.

9. A computer device, characterized in that: It includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the dry-type bushing capacitor core moisture defect detection method based on dielectric properties as described in any one of claims 1 to 6.

10. An information data processing terminal, characterized in that: The information data processing terminal includes the dry-type bushing capacitor core moisture defect detection system based on dielectric properties as described in claim 7.

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