Nondestructive testing method, system and equipment for moisture content of insulation paper, medium and product

Abstract

The invention discloses a nondestructive testing method, system and equipment for the moisture content of insulation paper, a medium and a product, and relates to the field of insulation paper moisture content detection.The method comprises the steps that an insulation paper standard sample with gradient moisture content is prepared, and the standard sample moisture content and a standard sample terahertz time-domain spectrum of the insulation paper standard sample are tested; determining a standard sample time domain signal according to the standard sample terahertz time domain spectrum, and calculating a peak ratio and a phase difference between the standard sample time domain signal and a reference signal; the peak ratio of the standard sample time domain signal to the reference signal and the phase difference are terahertz characteristic parameters; fitting the ratio of the peak ratio to the phase difference with the water content of the standard sample, and determining a quantitative evaluation curve; and inputting the terahertz time-domain spectrum of a to-be-detected insulation paper sample into the quantitative evaluation curve, and determining the water content of the to-be-detected insulation paper sample, so that the water content evaluation error can be reduced, and the application range is expanded.

Description

Technical Field

[0001] The present application relates to the field of detecting the water content of insulating paper, and particularly to a non-destructive method, system, device, medium and product for detecting the water content of insulating paper. Background Art

[0002] As a key component in the power system, the safety and stability of oil-immersed power transformers are crucial for the operation of the power grid. Statistical data shows that more than half of transformer failures are caused by the deterioration of the oil-paper insulation system. Therefore, effectively evaluating the state of the oil-paper insulation inside the transformer, especially its water content, is of great significance for preventing power grid accidents and improving the operation reliability of transformers. Currently, the water content of insulating paper is mainly evaluated by methods such as traditional electrical measurement methods, infrared methods, microwave methods, dielectric response methods, and Karl Fischer titration methods. These traditional methods usually only provide qualitative evaluations and cannot achieve accurate and non-destructive moisture detection. In addition, these methods often rely on cumbersome sample processing and slow testing processes and are not suitable for rapid applications in the field or on the production line.

[0003] As an emerging detection technology, terahertz technology shows great potential in the field of non-destructive detection. Research has shown that terahertz waves are highly sensitive to moisture and can accurately detect the influence of trace moisture on the terahertz spectrum.

[0004] Existing research has applied terahertz technology to water content detection. The characteristic quantity extracted by the existing method is the imaginary part of the complex dielectric constant of the sample. This characteristic quantity requires calculating the refractive index of the sample, and for different terahertz devices, this characteristic quantity varies greatly. Therefore, the detection result error caused by evaluating the water content of insulating paper based on this characteristic quantity is relatively large. Summary of the Invention

[0005] The purpose of the present application is to provide a non-destructive method, system, device, medium and product for detecting the water content of insulating paper to solve the problem of large errors in the detected water content.

[0006] To achieve the above purpose, the present application provides the following solutions:

[0007] In a first aspect, the present application provides a non-destructive method for detecting the water content of insulating paper, including:

[0008] Preparing insulating paper standard samples with gradient water contents, and testing the water content of the standard samples and the terahertz time-domain spectra of the standard samples;

[0009] Determining the standard sample time-domain signal according to the terahertz time-domain spectrum of the standard sample, and calculating the peak ratio and phase difference between the standard sample time-domain signal and the reference signal; the peak ratio and phase difference between the standard sample time-domain signal and the reference signal are terahertz characteristic parameters;

[0010] Fit the ratio of the peak ratio to the phase difference with the moisture content of the standard sample to determine a quantitative evaluation curve;

[0011] Input the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the moisture content of the insulating paper sample to be measured.

[0012] In a second aspect, the present application provides a non-destructive detection system for the moisture content of insulating paper, including:

[0013] A measurement module for preparing insulating paper standard samples with gradient moisture contents and testing the moisture content of the standard samples and the terahertz time-domain spectra of the standard samples;

[0014] A calculation module for determining the time-domain signal of the standard sample according to the terahertz time-domain spectrum of the standard sample and calculating the peak ratio and phase difference between the time-domain signal of the standard sample and the reference signal; the peak ratio and phase difference between the time-domain signal of the standard sample and the reference signal are terahertz characteristic parameters;

[0015] A fitting module for fitting the ratio of the peak ratio to the phase difference with the moisture content of the standard sample to determine a quantitative evaluation curve;

[0016] A moisture content determination module for inputting the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the moisture content of the insulating paper sample to be measured.

[0017] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor executes the computer program to implement the above non-destructive detection method for the moisture content of insulating paper.

[0018] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the above non-destructive detection method for the moisture content of insulating paper.

[0019] In a fifth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the above non-destructive detection method for the moisture content of insulating paper.

[0020] According to the specific embodiments provided by the present application, the present application has the following technical effects:

[0021] In this application, gradient water content insulating paper samples were prepared, and the samples were tested using the established terahertz non-destructive testing system. According to the test results, the ratio of the peak value of the terahertz time-domain spectroscopy signal of the insulating cardboard to the peak value of the reference signal and the ratio of the phase difference were determined as the terahertz characteristic parameters of the micro-water insulating cardboard, and a quantitative evaluation curve was fitted to evaluate the water content of the insulating paper, realizing the rapid non-destructive detection of the trace water content of the insulating paper. It can be seen that this application uses the peak ratio and phase difference of the signal of the insulating paper sample relative to the reference signal as the characteristics for evaluating the water content, without calculating the refractive index of the sample, with small errors, applicable to different terahertz devices, and having wide applicability. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is an application environment diagram of a non-destructive testing method for the water content of insulating paper in an embodiment of this application;

[0024] Figure 2 It is a schematic flowchart of a non-destructive testing method for the water content of insulating paper provided in an embodiment of this application;

[0025] Figure 3 It is a schematic diagram of an insulating paper block before processing provided in an embodiment of this application;

[0026] Figure 4 It is a schematic diagram of an insulating paper block after drying and oil immersion provided in an embodiment of this application;

[0027] Figure 5 It is a schematic structural diagram of a transmission terahertz time-domain spectroscopy system provided in an embodiment of this application;

[0028] Figure 6 It is a schematic diagram of the terahertz time-domain spectroscopy of insulating paper samples with different water contents provided in an embodiment of this application;

[0029] Figure 7 It is a schematic diagram of the fitted quantitative evaluation curve provided in an embodiment of this application;

[0030] Figure 8 It is a schematic flowchart of another non-destructive testing method for the water content of insulating paper provided in an embodiment of this application;

[0031] Figure 9 It is a schematic structural diagram of a computer device provided in an embodiment of this application. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0033] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the drawings and specific implementation manners.

[0034] The non-destructive detection method for the water content of insulating paper provided in the embodiments of the present application can be applied to an application environment as Figure 1 shown. Among them, the terminal 102 communicates with the server 104 through a network. The data storage system can store the data that the server 104 needs to process. The data storage system can be set separately, integrated on the server 104, or placed on the cloud or other servers. The terminal 102 can send the terahertz time-domain spectrum of the insulating paper sample to be measured to the server 104. After receiving the terahertz time-domain spectrum of the insulating paper sample to be measured, for the terahertz time-domain spectrum to be processed, the server 104 determines the standard sample time-domain signal according to the standard sample terahertz time-domain spectrum, and calculates the peak ratio and phase difference between the standard sample time-domain signal and the reference signal; the peak ratio and phase difference between the standard sample time-domain signal and the reference signal are terahertz characteristic parameters; the ratio of the peak ratio to the phase difference is fitted with the water content of the standard sample to determine a quantitative evaluation curve; the terahertz time-domain spectrum of the insulating paper sample to be measured is input into the quantitative evaluation curve to determine the water content of the insulating paper sample to be measured. The server 104 can feedback the obtained water content of the insulating paper sample to be measured to the terminal 102. In addition, in some embodiments, the non-destructive detection method for the water content of insulating paper can also be implemented by the server 104 or the terminal 102 alone. For example, the terminal 102 can directly perform non-destructive detection of the water content of the insulating paper sample to be measured, or the server 104 can obtain the terahertz time-domain spectrum of the insulating paper sample to be measured from the data storage system and perform non-destructive detection of the water content of the insulating paper sample to be measured.

[0035] Among them, the terminal 102 can be, but is not limited to, various desktop computers, laptop computers, smart phones, tablet computers, Internet of Things devices, and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart in-vehicle devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The server 104 can be implemented by an independent server or a server cluster composed of multiple servers, and can also be a cloud server.

[0036] In an exemplary embodiment, as Figure 2 shown, a non-destructive detection method for the water content of insulating paper is provided. This method is executed by a computer device, and specifically, it can be executed alone by a computer device such as a terminal or a server, or jointly executed by a terminal and a server. In the embodiments of the present application, taking the method applied to Figure 1 the server 104 in

[0037] S1: Prepare a gradient water content insulating paper standard sample, and test the standard sample water content and the standard sample terahertz time-domain spectrum of the insulating paper standard sample.

[0038] S2: Determine the standard sample time-domain signal according to the standard sample terahertz time-domain spectrum, and calculate the peak ratio and phase difference between the standard sample time-domain signal and the reference signal; the peak ratio and phase difference between the standard sample time-domain signal and the reference signal are terahertz characteristic parameters.

[0039] S3: Fit the ratio of the peak ratio to the phase difference with the standard sample water content to determine a quantitative evaluation curve.

[0040] S4: Input the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the water content of the insulating paper sample to be measured.

[0041] In an exemplary embodiment, preparing a gradient water content insulating paper standard sample specifically includes:

[0042] Cut the insulating paper into multiple insulating paper blocks.

[0043] Treat the non-impregnated insulating paper blocks with different drying temperatures and drying times to determine multiple dried insulating paper blocks.

[0044] Immerse the dried insulating paper blocks in insulating oil to prepare a gradient water content insulating paper standard sample.

[0045] In practical applications, preparing a gradient water content insulating paper standard sample is as follows:

[0046] In this application, 1-mm thick Wedemann paper is selected and naturally absorbs moisture at room temperature. The initial water content is measured to be 6.5% by the Karl Fischer titration method. To obtain samples with different water contents, the insulating oil paper is processed as follows:

[0047] (1) Take the insulating oil into a beaker and vacuum dry it for 48 h.

[0048] (2) Cut the insulating cardboard into squares with a side length of 3 cm, as Figure 3 shown.

[0049] (3) Treat the unimpregnated insulating paper blocks with different drying temperatures and drying times. The drying conditions of each sample are shown in Table 1.

[0050] (4) Put the dried insulating paper blocks of each group into insulating oil, soak them completely to keep their moisture, and seal the bottle mouth with plastic wrap.

[0051] After being processed through the above process, Figure 4 the test specimens shown below are obtained.

[0052] In an exemplary embodiment, measure the moisture content of the insulating paper specimen and the terahertz time-domain spectrum of the specimen, specifically including: measuring the moisture content of the insulating paper specimen using the Karl Fischer titration method.

[0053] Build a transmission terahertz time-domain spectroscopy system to measure the terahertz time-domain spectrum of the insulating paper specimen.

[0054] In practical applications, the moisture content of the insulating paper specimen is measured as follows:

[0055] To determine the moisture content of each group of samples, the present application uses the Karl Fischer titration method to calibrate its moisture content. The moisture content of each sample is shown in Table 1.

[0056] Table 1 Drying conditions and moisture content of samples

[0057] Sample Number Drying Temperature / °C Drying Time / h Water Content / % 1 90 24 0.452 2 90 2 0.895 3 60 2 2.156 4 90 1 3.803 5 60 1 4.187 6 None None 4.671

[0058] In an exemplary embodiment, build a transmission terahertz time-domain spectroscopy system to measure the terahertz time-domain spectrum of the insulating paper specimen, specifically including:

[0059] The transmission terahertz time-domain spectroscopy system includes a femtosecond laser, a beam splitter, a time delay line, a parabolic mirror, a terahertz emitter, a terahertz detector, and a computer.

[0060] Use the femtosecond laser to generate femtosecond laser light.

[0061] Use the beam splitter to split the femtosecond laser light into pump light and probe light; the pump light is used to excite terahertz waves through the time delay line and the terahertz emitter to generate THz pulses.

[0062] Collimate the THz pulses through a pair of parabolic mirrors, focus them onto the insulating paper specimen, transmit the THz pulses carrying specimen information through the insulating paper specimen, collimate them through another pair of parabolic mirrors, and focus them collinearly with the probe light onto the terahertz detector.

[0063] Let the terahertz detector convert the detection light and the THz pulse carrying the standard sample information into an electrical signal corresponding to the standard sample signal, and input it into the computer to generate a standard sample terahertz time-domain spectrum.

[0064] In practical applications, a transmission terahertz time-domain spectroscopy system is built as follows:

[0065] To test the water content of transformer insulating paper containing micro water, a transmission terahertz time-domain spectroscopy system is built in this application, as Figure 5 shown, mainly including a Menlo femtosecond laser, a beam splitter, a Batop photoconductive antenna, a time delay control system, a parabolic mirror, a THz wave detector, a two-dimensional scanning translation stage, and a computer.

[0066] First, a femtosecond laser pulse (Fs pulse) is emitted by the femtosecond laser. This pulse is split by the beam splitter into two mutually perpendicular beams of light: the pump beam and the probe beam. Then, the pump beam is focused onto the substrate surface of the photoconductive antenna through a mirror and a time delay device to generate a THz pulse. The THz pulse is collimated and focused onto the sample to be measured through a parabolic mirror. After the THz pulse carrying the sample information transmits through the sample, it is collimated and focused by another pair of parabolic mirrors, and passes through the detector collinearly with the probe light. Finally, the detector sends this signal to the computer for further data analysis and processing.

[0067] The main functions of each part are as follows:

[0068] 1. Femtosecond laser: Generate femtosecond laser with ultra-short pulses (the pulse width is usually between dozens and hundreds of femtoseconds).

[0069] 2. Beam splitter: Split the femtosecond laser into two beams, one for exciting terahertz waves (pump beam), and the other for detection (probe beam).

[0070] Pump beam: Transmit to the photoconductive antenna and pass through the terahertz emitter to excite terahertz waves.

[0071] Probe beam: Propagate through the optical fiber to the terahertz detector.

[0072] 4. Time delay line: Adjust the optical path of the probe beam, thereby controlling the relative time delay between the probe beam and the terahertz wave in the detector, and realizing time-resolved measurement.

[0073] 5. Parabolic mirror: Collimate and focus terahertz waves, so that terahertz waves are concentrated and can effectively irradiate the sample, or be transmitted to the detector.

[0074] 6. THz wave generator, that is, terahertz generator: Used to emit terahertz waves.

[0075] 7. THz wave detector, i.e., terahertz detector: It detects the terahertz wave after passing through the sample and converts the terahertz signal into an electrical signal that is easy to measure through the electro-optic effect or photoconductive effect.

[0076] 8. Two-dimensional scanning platform: It moves the sample in the horizontal direction to achieve terahertz scanning test.

[0077] 9. Lock-in amplifier: It extracts the weak terahertz signal from the strong noise background.

[0078] 10. Computer: It is used for data acquisition and processing, records the time-domain signal of the terahertz pulse, and conducts analysis. The analysis process is as follows: Extract the peaks of the time-domain waveforms of the reference signal and the sample signal, and calculate the peak ratio; Extract the phases of the time-domain waveforms of the reference signal and the sample signal, and calculate the phase difference.

[0079] In this application, air is selected as the reference signal, and samples 1 - 6 are used as the sample signals for terahertz testing. To improve the test accuracy and eliminate test errors, each sample is subjected to 256 terahertz tests in the system, and the average value of the test results is taken. Nitrogen is used to reduce the humidity of the terahertz optical path to below 3% RH.

[0080] In an exemplary embodiment, calculating the peak ratio and phase difference between the time-domain signal of the standard sample and the reference signal specifically includes: Using the computer to extract the peak and phase of the time-domain waveform of the time-domain signal of the standard sample from the electrical signal, and extract the peak and phase of the time-domain waveform of the reference signal; Calculate the peak ratio and phase difference according to the peaks and phases of the time-domain signal of the standard sample and the reference signal.

[0081] In practical applications, measure the terahertz time-domain spectrum of the standard sample and establish the following quantitative evaluation curve for the moisture content of insulating paper:

[0082] Use the built terahertz time-domain spectroscopy system to test the time-domain waveforms of insulating paperboards with different moisture contents in the terahertz band as Figure 6 shown. The equilibrium position of water molecules is approximately between 240 ps and 243 ps. Due to the interaction of water molecules with terahertz waves, phenomena such as absorption, changes in the relaxation times of translational and rotational motions will occur, resulting in changes in the peak and phase of the transmitted terahertz waveform. As the moisture content increases, the absorption of the oil-paper sample for terahertz waves gradually increases, and the transmission intensity decreases accordingly. Therefore, the peak of the sample signal (the arrow in Figure 6 is regarded as the peak) decreases; At the same time, as the moisture content increases, the dielectric constant of the oil-paper sample increases. For a medium with a higher dielectric constant, the propagation speed of electromagnetic waves inside it is lower. Therefore, the peak time will be delayed as the moisture content increases.

[0083] The peak ratios and phase differences of the six groups of sample signals relative to the air reference signal are shown in Table 2, and the water contents of the six groups of samples obtained by the Karl Fischer titration method are also listed.

[0084] Table 2 Peak Ratios and Phase Differences of Samples

[0085] Sample Number Peak Ratio Phase Difference / ps Water Content / % 1 0.5090 2.1017 0.452 2 0.4663 2.1818 0.895 3 0.4006 2.3619 2.156 4 0.3573 2.3820 3.803 5 0.3456 2.4187 4.187 6 0.2920 2.4420 4.671

[0086] There is a large correlation between the water content in Table 2 and the peak amplitude and peak delay time of the signal. Therefore, the peak intensity (F) and phase delay (ΔT) in the time domain can be used as comprehensive indicators to distinguish the water content of oil-paper. The time-domain peak ratio / phase difference (F / ΔT, 1 / ps) of the test signal is extracted as a characteristic parameter and fitted with the water content of the insulating paper standard sample. The fitting results are as Figure 7 shown.

[0087] The quantitative evaluation curve is: H = A * F / ΔT + B; where, H is the water content; A and B are fitting coefficients, taking A = -0.02529 and B = 0.24113; F is the peak ratio; ΔT is the phase difference; the goodness of fit is 0.9345.

[0088] In practical applications, the terahertz absorption spectrum of the insulating paper sample to be tested is measured, and the terahertz time-domain spectrum is extracted and brought into the quantitative evaluation curve to obtain the water content.

[0089] This application selects two types of cardboard with low water content and high water content to verify the accuracy of the proposed method.

[0090] As Figure 8 shown, first, the water content of the cardboard is obtained by the Karl Fischer titration method. Then, the terahertz time-domain spectrum waveform of the cardboard is measured using the built terahertz time-domain spectroscopy system, and the peak ratio (F) and phase difference (ΔT) of the sample signal relative to the reference signal are extracted, and the characteristic peak ratio / phase difference (F / ΔT) is calculated. The calculated peak ratio / phase difference is brought into the quantitative evaluation curve to obtain the water content of the insulating cardboard. The water contents measured by the two methods are shown in Table 3. It can be seen from Table 3 that the error between the two is within 5%, indicating that the method proposed in this application can achieve rapid and non-destructive evaluation of the water content of insulating cardboard.

[0091] Table 3 Test Results of the Water Content of Insulating Cardboard

[0092] Sample Terahertz Evaluated Water Content (%) Karl Fischer Titration Method Tested Water Content (%) Low Water Content Cardboard 0.641 0.672 High Water Content Cardboard 4.448 4.589

[0093] 1. Using terahertz time-domain spectroscopy technology, the water content of insulating paper can be detected non-contact and non-destructively, efficiently and quickly.

[0094] 2. The water content of insulating paper is one of the important characterization parameters for evaluating the performance of insulating paper. Currently, in the laboratory, a Karl Fischer titrator is used to measure the water content of insulating paper, which is time-consuming, can damage the sample, and has cumbersome operation steps. This application can quickly and nondestructively evaluate the water content of insulating paper.

[0095] Based on the same inventive concept, the embodiments of this application also provide a nondestructive detection system for the water content of insulating paper. The solution provided by this system to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the nondestructive detection system for the water content of insulating paper provided below can refer to the limitations for the nondestructive detection method of the water content of insulating paper in the above text, and will not be repeated here.

[0096] In an exemplary embodiment, a nondestructive detection system for the water content of insulating paper is provided, including:

[0097] A measurement module, configured to prepare a gradient water content insulating paper standard sample, and measure the water content and terahertz time-domain spectrum of the insulating paper standard sample.

[0098] A calculation module, configured to determine the time-domain signal of the standard sample according to the terahertz time-domain spectrum of the standard sample, and calculate the peak ratio and phase difference between the time-domain signal of the standard sample and a reference signal; the peak ratio and phase difference between the time-domain signal of the standard sample and the reference signal are terahertz characteristic parameters.

[0099] A fitting module, configured to fit the ratio of the peak ratio to the phase difference with the water content of the standard sample to determine a quantitative evaluation curve.

[0100] A water content determination module, configured to input the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the water content of the insulating paper sample to be measured.

[0101] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the steps in the above method embodiments are implemented. This computer device can be a server or a terminal, and its internal structure diagram can be as Figure 9As shown in the figure. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data to be processed. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals through a network connection. When the computer program is executed by the processor, it implements a method for non-destructive detection of the water content of insulating paper.

[0102] Those skilled in the art can understand that Figure 9 The structure shown in the figure is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the steps in the above method embodiments are implemented.

[0103] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by the processor, the steps in the above method embodiments are implemented.

[0104] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by the processor, the steps in the above method embodiments are implemented.

[0105] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0106] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the various embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memories can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0107] The databases involved in the various embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the various embodiments provided in the present application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0108] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0109] Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A non-destructive detection method for the water content of insulating paper, characterized in that, Comprising: Preparing an insulating paper standard sample with a gradient water content, and testing the water content of the standard sample of the insulating paper and the terahertz time-domain spectrum of the standard sample; Determining the standard sample time-domain signal according to the terahertz time-domain spectrum of the standard sample, and calculating the peak ratio and phase difference between the standard sample time-domain signal and the reference signal; the peak ratio and phase difference between the standard sample time-domain signal and the reference signal are terahertz characteristic parameters; Fitting the ratio of the peak ratio to the phase difference with the water content of the standard sample to determine a quantitative evaluation curve; Inputting the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the water content of the insulating paper sample to be measured.

2. The non-destructive detection method for the water content of the insulating paper according to claim 1, wherein Preparing an insulating paper standard sample with a gradient water content, specifically including: Cutting the insulating paper into multiple insulating paper blocks; Processing the unimpregnated insulating paper blocks with different drying temperatures and drying times to determine multiple dried insulating paper blocks; Soaking the dried insulating paper blocks in insulating oil to prepare an insulating paper standard sample with a gradient water content.

3. The non-destructive detection method for the water content of the insulating paper according to claim 1, characterized in that Testing the water content of the standard sample of the insulating paper and the terahertz time-domain spectrum of the standard sample, specifically including: Measuring the water content of the standard sample of the insulating paper by using the Karl Fischer titration method; Building a transmission terahertz time-domain spectroscopy system to measure the terahertz time-domain spectrum of the standard sample of the insulating paper.

4. The non-destructive detection method for the water content of the insulating paper according to claim 3, wherein Building a transmission terahertz time-domain spectroscopy system to measure the terahertz time-domain spectrum of the standard sample of the insulating paper, specifically including: The transmission terahertz time-domain spectroscopy system includes a femtosecond laser, a beam splitter, a time delay line, a parabolic mirror, a terahertz emitter, a terahertz detector, and a computer; Generating femtosecond laser by using the femtosecond laser; Dividing the femtosecond laser into a pump light and a probe light by using the beam splitter; the pump light is used to excite terahertz waves through the time delay line and the terahertz emitter to generate THz pulses; Collimating the THz pulses through a pair of parabolic mirrors, focusing them on the insulating paper standard sample, transmitting the THz pulses carrying the standard sample information through the insulating paper standard sample, collimating them through another pair of parabolic mirrors, and focusing them on the terahertz detector collinearly with the probe light; Converting the probe light and the THz pulses carrying the standard sample information into electrical signals corresponding to the standard sample signals by using the terahertz detector, and inputting them into the computer to generate the terahertz time-domain spectrum of the standard sample.

5. The non-destructive detection method for the water content of the insulating paper according to claim 4, wherein Calculating the peak ratio and phase difference between the standard sample time-domain signal and the reference signal, specifically including: Extracting the peak and phase of the time-domain waveform of the standard sample time-domain signal from the electrical signal by using the computer, and extracting the peak and phase of the time-domain waveform of the reference signal; Calculating the peak ratio and phase difference according to the peak and phase of the standard sample time-domain signal and the reference signal.

6. The non-destructive detection method for the water content of the insulating paper according to claim 1, characterized in that, The quantitative evaluation curve is: H = A * F / ΔT + B; Wherein, H is the water content; A and B are fitting coefficients; F is the peak ratio; ΔT is the phase difference.

7. An insulating paper moisture content non-destructive testing system, characterized in that, Including: A measurement module for preparing an insulating paper standard sample with a gradient water content, and testing the water content of the standard sample of the insulating paper and the terahertz time-domain spectrum of the standard sample; A calculation module, configured to determine a standard sample time-domain signal according to the terahertz time-domain spectrum of the standard sample, and calculate a peak ratio and a phase difference between the standard sample time-domain signal and a reference signal; the peak ratio and the phase difference between the standard sample time-domain signal and the reference signal are terahertz characteristic parameters; A fitting module, configured to fit the ratio of the peak ratio to the phase difference with the water content of the standard sample to determine a quantitative evaluation curve; A water content determination module, configured to input the terahertz time-domain spectrum of the insulating paper sample to be measured into the quantitative evaluation curve to determine the water content of the insulating paper sample to be measured.

8. A computer device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the computer program to implement the non-destructive detection method for the water content of insulating paper according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the non-destructive detection method for the water content of insulating paper according to any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the non-destructive detection method for the water content of insulating paper according to any one of claims 1-6.

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