Metal pipeline conductivity measuring method based on high-frequency eddy current

Abstract

The invention provides a high-frequency eddy current-based metal pipeline conductivity measurement method, which comprises the following steps: designing an absolute eddy current sensor, positioning a sensor coil on the inner side of a metal pipeline and coaxially arranging the sensor coil and the pipeline, and introducing high-frequency alternating current into the coil to generate eddy current; establishing a simplified high-frequency eddy current detection analysis theoretical model, and setting geometric dimensions of a sensor and a pipeline; a Bessel function and a spatial resolution expression are used for analyzing the relation between the real part of the eddy current impedance change under high-frequency excitation and the conductivity of the pipeline; setting the conductivity of the metal pipeline according to the analysis result, and fitting the relation between the impedance change and the conductivity through a power function; and according to a coil impedance measurement result, combining the fitted power function curve, and performing inversion to obtain the actual conductivity of the metal pipeline. According to the invention, the conductivity of the metal pipeline can be effectively measured.

Description

Technical Field

[0001] The present application relates to the technical field of non-contact measurement of electromagnetic characteristics of metal pipelines using electromagnetic eddy currents, and in particular to a method for measuring the electrical conductivity of metal pipelines based on high-frequency eddy currents. Background Art

[0002] Metal pipes have been widely used in the construction, petrochemical, power and other industries due to their superior strength, corrosion resistance and good high pressure resistance. However, metal pipes need to withstand a variety of loads during service, especially under long-term service conditions, their structures will be subject to different degrees of stress and fatigue. Excessive stress may cause plastic deformation, cracks or even failure of metal pipes, posing a serious threat to the safe operation of the system. Therefore, damage detection and performance evaluation of metal pipes in service are of great engineering significance.

[0003] The electromagnetic properties of metal pipes are closely related to their microstructure, chemical properties and mechanical properties. For example, changes in the microstructure of the pipe will lead to changes in electromagnetic parameters such as conductivity. By measuring the electromagnetic parameters of metal pipes, its fatigue, defects and other damage states can be indirectly evaluated, thereby achieving non-destructive testing and condition monitoring. Based on this characteristic, the use of electromagnetic technology to detect metal pipes has become a research hotspot in the current field of non-destructive testing.

[0004] Eddy current testing technology is a non-destructive testing method based on the principle of electromagnetic induction. Its core is to detect the changes in the induced eddy currents in the object being tested, and then evaluate the electromagnetic properties of the object being tested, such as conductivity and conductivity. Eddy current testing has the advantages of high sensitivity, fast detection speed, and non-contact measurement. It is particularly suitable for the detection of defects, corrosion, fatigue and conductive properties of metal materials. In addition, eddy current testing can also achieve in-depth detection of metal materials of different thicknesses through the skin effect, and has a wide range of application scenarios.

[0005] At present, the application of traditional eddy current testing methods in the detection of electrical conductivity of metal pipelines still has certain limitations, such as insufficient detection accuracy and weak ability to adapt to complex working conditions. Summary of the invention

[0006] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0007] To this end, the first objective of the present application is to propose a method for measuring the electrical conductivity of a metal pipe based on high-frequency eddy current.

[0008] The second objective of the present application is to provide a metal pipe conductivity measuring device based on high-frequency eddy current.

[0009] The third objective of the present application is to provide an electronic device.

[0010] A fourth objective of the present application is to provide a computer-readable storage medium.

[0011] A fifth object of the present application is to provide a computer program product.

[0012] To achieve the above-mentioned purpose, the first embodiment of the present application proposes a method for measuring the electrical conductivity of a metal pipeline based on high-frequency eddy current, comprising:

[0013] An absolute eddy current sensor is designed, wherein the coil of the eddy current sensor is located inside the metal pipe and is coaxially arranged with the metal pipe, and a high-frequency alternating current is passed through the coil, so that an eddy current is generated in the metal pipe;

[0014] Establishing a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes, and setting the geometric dimensions of the coil and the metal pipe;

[0015] According to the characteristics of Bessel function and the expression of spatial resolution, the relationship between the real part of eddy current impedance change and the conductivity of metal pipe under high frequency excitation is analyzed.

[0016] The conductivity of the metal pipeline is set according to the analysis result, and the set conductivity of the metal pipeline is input into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and the relationship between the real part of the impedance change and the conductivity is fitted by a power function;

[0017] According to the coil impedance measurement result, combined with the fitted power function curve, the actual conductivity of the metal pipeline is obtained by inversion.

[0018] Optionally, the geometric dimensions of the coil and the metal pipe include: the inner diameter r1 of the coil, the outer diameter r2 of the coil, the height l2-l1 of the coil, the number of coil turns n and the inner diameter a of the metal pipe.

[0019] Optionally, the calculation expression of the simplified analytical theoretical model of high-frequency eddy current detection of metal pipes includes the impedance amplitude term Z0 determined by the coil size and the phase term S(α0) determined by the electromagnetic characteristics and size of the metal pipe. Due to the existence of the metal pipe, the expression of the coil impedance change ΔZ is:

[0020] ΔZ=S(α0)Z0

[0021] Where:

[0022]

[0023] Where ω is the angular frequency of the excitation current, μ0 is the magnetic permeability, α0 is the spatial resolution, which is approximately calculated by the inverse of the average radius of the coil, I0 and I1 are the 0th and 1st order first-kind modified Bessel functions, K0 and K1 are the 0th and 1st order second-kind modified Bessel functions, and α1 is a complex-valued electromagnetic propagation constant.

[0024] Optionally, the analysis of the relationship between the real part of the eddy current impedance change and the conductivity of the metal pipe under high-frequency excitation according to the characteristics of the Bessel function and the spatial resolution expression includes:

[0025] When the excitation frequency reaches the MHz level, the following conditions are met:

[0026] αK1(α1a)I0(α0a)<<α1K0(α1a)I1(α0a)

[0027] and

[0028]

[0029] Substituting α1 into the coil impedance phase term S(α0), the approximate expression of the coil impedance phase term S(α0) is obtained as follows:

[0030]

[0031] At this time, the real part expression of the coil impedance change ΔZ is:

[0032]

[0033] The real part of the coil impedance change increases with the increase of the excitation frequency, and the real part of the impedance change is in an inverse square root relationship with the conductivity σ of the metal pipe.

[0034] Optionally, the metal pipeline conductivity is set according to the analysis result, and the set metal pipeline conductivity is input into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and the relationship between the real part of the impedance change and the conductivity is fitted by a power function, including:

[0035] According to the relationship between the real part of the eddy current impedance change and the conductivity of the metal pipeline under high-frequency excitation, multiple groups of metal pipeline conductivity σ are set. i , and the simplified analytical theoretical model for high-frequency eddy current detection of metal pipelines is used to calculate the corresponding real part of the impedance change ΔZ i ;

[0036] Determine the conductivity σ of metal pipes i Is the number of settings greater than the threshold required for fitting? If not, return to the previous step and reset the metal pipe conductivity σ i ;

[0037] If it is satisfied, then according to the real part expression of impedance change, the power function y=kx -1 / 2 Fitting impedance change real part real(ΔZ i ) and the electrical conductivity σ of the metal pipe.

[0038] Optionally, the actual conductivity of the metal pipe is obtained by inverting the coil impedance measurement result in combination with the fitted power function curve, including:

[0039] Obtain the real part value of the actual measured coil impedance change real(ΔZ);

[0040] Substitute the measurement results into the fitted power function curve and use the formula k / (ΔZ 2 ) is inverted to obtain the actual conductivity of the metal pipe.

[0041] To achieve the above-mentioned purpose, the second embodiment of the present application proposes a metal pipeline conductivity measurement device based on high-frequency eddy current, comprising:

[0042] An eddy current sensor design module is used to design an absolute eddy current sensor. The coil of the eddy current sensor is located inside the metal pipe and is coaxially arranged with the metal pipe. A high-frequency alternating current is passed through the coil to generate eddy current in the metal pipe.

[0043] An analytical theoretical modeling module is used to establish a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes and set the geometric dimensions of the coil and the metal pipe;

[0044] Impedance and conductivity analysis module, used to analyze the relationship between the real part of eddy current impedance change and the conductivity of metal pipes under high-frequency excitation based on the characteristics of Bessel function and spatial resolution expression;

[0045] A conductivity fitting module is used to set the conductivity of the metal pipeline according to the analysis results, and input the set conductivity of the metal pipeline into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and fit the relationship between the real part of the impedance change and the conductivity through a power function;

[0046] The conductivity inversion module is used to invert the actual conductivity of the metal pipeline according to the coil impedance measurement result in combination with the fitted power function curve.

[0047] To achieve the above-mentioned purpose, the third aspect of the present application provides an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0048] The memory stores computer-executable instructions;

[0049] The processor executes the computer-executable instructions stored in the memory to implement the method as described in any one of the first aspects.

[0050] To achieve the above-mentioned purpose, the fourth aspect embodiment of the present application proposes a computer-readable storage medium, in which computer-readable storage medium is stored computer execution instructions, and when the computer execution instructions are executed by a processor, they are used to implement the method as described in any one of the first aspects.

[0051] To achieve the above-mentioned purpose, the fifth aspect of the present application proposes a computer program product, which implements any method in the first aspect when executed by a processor.

[0052] The technical solution provided by the embodiments of the present application brings at least the following beneficial effects:

[0053] By combining high-frequency eddy current detection technology with analytical theoretical models and mathematical fitting methods, the relationship between the real part of the eddy current impedance change and the electrical conductivity of the metal pipe can be accurately established, achieving high-precision measurement of the electrical conductivity of the metal pipe. The entire detection process is a non-contact design, and there is no need to directly contact the surface of the metal pipe, which effectively avoids the damage to the pipe surface that may be caused by traditional contact measurement. It is suitable for non-destructive detection under a variety of complex working conditions.

[0054] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0056] Figure 1 A schematic flow chart of a method for measuring the electrical conductivity of a metal pipe based on high-frequency eddy current provided in an embodiment of the present application;

[0057] Figure 2 A schematic diagram of the configuration of coils and metal components in the classic Dodd-Deeds eddy current analytical theoretical model provided in an embodiment of the present application;

[0058] Figure 3 A schematic diagram of the configuration of coils and pipes in a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes provided in an embodiment of the present application;

[0059] Figure 4 A schematic diagram showing a comparison between the calculation results of the simplified analytical theoretical model for high-frequency eddy current detection of metal pipes in the sweep frequency mode provided in an embodiment of the present application and the original Dodd-Deeds theoretical model;

[0060] Figure 5A schematic diagram of the relationship between the real part of the coil impedance change and the conductivity caused by the sample at different conductivities under 1 MHz excitation provided in the embodiment of the present application;

[0061] Figure 6 A schematic diagram of the structure of a metal pipe conductivity measuring device based on high-frequency eddy current provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0063] In view of the problems existing in the prior art, the present invention provides a method for measuring the electrical conductivity of a metal pipe based on high-frequency eddy current. Figure 1 The following is a schematic diagram of a method for measuring the electrical conductivity of a metal pipe based on high-frequency eddy currents provided in an embodiment of the present application. Figure 1 As shown, the method comprises the following steps:

[0064] S1. Design an absolute eddy current sensor. The coil of the eddy current sensor is located on the inner side of the metal pipe and is coaxially arranged with the metal pipe. A high-frequency alternating current is passed through the coil to generate eddy currents in the metal pipe.

[0065] In this step, an absolute eddy current sensor is designed to realize high-frequency eddy current detection of the electrical conductivity of metal pipes. The coil of the eddy current sensor is arranged on the inner side of the metal pipe and coaxially with the metal pipe to ensure the uniform distribution of the induced magnetic field and the sensitivity and stability of the detection. By passing a high-frequency alternating current through the coil, eddy currents are induced on the surface of the metal pipe, realizing non-contact measurement based on the principle of electromagnetic induction. In the specific design, the eddy current skin depth is much smaller than the pipe wall thickness, thereby enhancing the sensitivity and accuracy of the surface conductivity measurement.

[0066] Specifically, the eddy current sensor uses a sinusoidal alternating current to excite the coil, causing eddy currents to be generated on the inner surface of the copper metal pipe. At the same time, the eddy current skin depth is controlled to be much smaller than the pipe wall thickness, effectively improving the accuracy and stability of the surface conductivity measurement. To ensure the detection performance, the size and number of turns of the coil are precisely designed, with the inner and outer diameters of the coil being 2mm and 5mm respectively, and the number of turns being 100. This design can provide sufficient magnetic field strength and ensure the stability of the induced signal.

[0067] When eddy currents are generated on the inner surface of a metal pipe, a secondary magnetic field is formed on the pipe surface. The strength and distribution of the secondary magnetic field are directly affected by electromagnetic properties such as the pipe conductivity. Subsequently, the secondary magnetic field generated by the eddy current is induced and received by the coil, and the impedance change of the coil is determined by the strength of the induced eddy current. Since the eddy current strength is closely related to the pipe conductivity, this impedance change becomes an important detection parameter for evaluating the conductivity of metal pipes.

[0068] Through the above design, this step not only achieves efficient generation and reception of eddy currents, but also provides high-precision impedance change data for subsequent analytical theoretical modeling and conductivity inversion. The entire detection process is non-contact, highly sensitive, and highly responsive, and is suitable for metal pipeline detection in a variety of industrial application scenarios.

[0069] S2. Establish a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes and set the geometric dimensions of the coil and the metal pipe.

[0070] This step establishes a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes to describe the relationship between the change in coil impedance and the conductivity of metal pipes. This step is based on the classic Dodd-Deeds eddy current analytical theoretical model, combined with actual detection conditions, and through assumptions and simplified processing, it significantly improves the calculation efficiency of the model while ensuring a high calculation accuracy.

[0071] Figure 2 The schematic diagram of the configuration of the coil and metal component in the classic Dodd-Deeds eddy current analytical theoretical model is shown. The classic model assumes that the metal component consists of a two-layer structure and calculates the impedance change of the coil using the following formula:

[0072]

[0073] In the formula, S(α) and D(α) represent functions related to coil parameters and electromagnetic properties of metal components, respectively. The specific expressions are shown in the following formula:

[0074]

[0075] At this time, the two-layer structure of the metal pipe is represented by the inner radius a and the outer radius b, and the electrical conductivities are σ1 and σ2 respectively.

[0076] When the excitation frequency reaches the MHz level, due to the skin effect, the eddy currents are concentrated on the surface of the metal pipe, causing the double-layer structure characteristics of the metal pipe to be ignored and then simplified to a single-layer structure. Figure 3 The schematic diagram of the configuration of the coil and the single-layer metal pipe in the simplified model is shown. Under the simplified conditions, assuming that σ1=σ2=σ, and b→∞, accordingly, S(α) and D(α) can be expressed as:

[0077]

[0078] In addition, S(α) in the ΔZ expression changes slowly compared to other integral variables, so it can be approximately extracted from the integral. Substituting S(α) and D(α) into ΔZ, we get:

[0079] ΔZ=S(α0)Z0

[0080] Among them, Z0 and S(α0) represent the impedance amplitude term determined by the coil size and the phase term determined by the electromagnetic characteristics and size of the metal pipe, respectively. The specific expressions are as follows:

[0081]

[0082] Where ω is the angular frequency of the excitation current, μ0 is the magnetic permeability, α0 is the spatial resolution, which is approximately calculated by the inverse of the average radius of the coil, I0 and I1 are the 0th and 1st order first-kind modified Bessel functions, K0 and K1 are the 0th and 1st order second-kind modified Bessel functions, and α1 is a complex-valued electromagnetic propagation constant.

[0083] When constructing a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes, it is necessary to set the geometric dimensions of the coil and the metal pipe in the model, including: the inner diameter r1 of the coil, the outer diameter r2 of the coil, the height l2-l1 of the coil, the number of coil turns n and the inner diameter a of the metal pipe.

[0084] In order to verify the effectiveness of the simplified model, the following parameters are set in this step: the conductivity of the metal pipe is 58MS / m, the inner radius and outer radius of the pipe are set to 6mm and 8mm respectively, and the excitation frequency range is set to 1kHz to 1MHz. The calculation results of the simplified model are compared with those of the classic Dodd-Deeds model, as shown in Figure 2. Figure 4 In the whole frequency range, the maximum relative error of the two models is only 0.1%, and the calculation speed of the simplified model is 19.9% ​​faster than that of the classical model.

[0085] Through the above simplified processing, this step effectively reduces the calculation complexity, provides fast and accurate theoretical support for the real-time detection of metal pipeline conductivity, and ensures the accuracy and reliability of high-frequency eddy current detection results.

[0086] S3. According to the characteristics of Bessel function and the expression of spatial resolution, the relationship between the real part of eddy current impedance change and the conductivity of metal pipe under high-frequency excitation is analyzed.

[0087] In the embodiment of the present application, based on the characteristics of the Bessel function and the expression of spatial resolution, the relationship between the real part of the eddy current impedance change and the conductivity of the metal pipe under high-frequency excitation is further analyzed. Through analytical derivation, the quantitative description of the conductivity of the metal pipe by the real part of the coil impedance change is realized, which provides a theoretical basis for the subsequent fitting and inversion of conductivity.

[0088] When the excitation frequency reaches the MHz level, the eddy current is mainly distributed on the surface of the metal pipe, and the following conditions are met:

[0089] αK1(α1a)I0(α0a)<<α1K0(α1a)I1(α0a)

[0090] And the complex electromagnetic propagation constant can be approximated as:

[0091]

[0092] Substituting the above conditions into the coil impedance phase term S(α0), we can get its approximate expression:

[0093]

[0094] On this basis, the real part expression of the coil impedance change ΔZ is:

[0095]

[0096] It can be seen from the above formula that the real part of the coil impedance change is closely related to the excitation frequency and the conductivity of the metal pipe. The real part of the impedance change increases with the increase of the excitation frequency ω, which shows that high-frequency excitation can effectively enhance the detection sensitivity; and the real part of the impedance change is in an inverse square root relationship with the conductivity σ of the metal pipe, that is:

[0097]

[0098] The physical meaning of the above relationship is that as the conductivity of the pipeline increases, the intensity of the induced eddy current decreases and the impedance change amplitude of the coil decreases. Through this negative correlation characteristic, the measured real part of the impedance change can be used to invert the conductivity of the pipeline.

[0099] In order to better verify the accuracy of the above formula, this step uses actual parameters for numerical calculation and analysis. Under the condition that the excitation frequency ranges from 1kHz to 1MHz, the calculation results show that the real part of the impedance change has a significant increasing trend in response to the excitation frequency, and the sensitivity of the real part of the impedance change to the conductivity of the metal pipe conforms to the characteristics of the inverse square root relationship. This result verifies the reliability of the theoretical model and provides a solid theoretical basis for the subsequent conductivity fitting.

[0100] Through the analysis of the above steps, this application successfully constructed a quantitative relationship between the real part of the impedance change and the conductivity of the metal pipe. Combined with the characteristics of high-frequency excitation, it provides theoretical support for achieving accurate conductivity measurement, and also significantly improves the sensitivity and applicability of the detection system.

[0101] S4. The electrical conductivity of the metal pipeline is set according to the analysis results, and the set electrical conductivity of the metal pipeline is input into the simplified analytical theoretical model of high-frequency eddy current detection of metal pipelines, and the relationship between the real part of the impedance change and the electrical conductivity is fitted by a power function.

[0102] In the embodiment of the present application, based on the relationship between the real part of the impedance change and the conductivity of the metal pipeline obtained by the analysis in step S3, different metal pipeline conductivity values ​​are further set, and the mathematical relationship between the real part of the impedance change and the conductivity is fitted by using a simplified analytical theoretical model of high-frequency eddy current detection of metal pipelines. Through the fitted power function relationship, a calculation method that is convenient for quickly inverting the conductivity of metal pipelines is established.

[0103] First, according to the relationship between the real part of the eddy current impedance change under high-frequency excitation and the conductivity of the metal pipe, the conductivity of the metal pipe σ is set. i , and the corresponding real part of the impedance change ΔZ is calculated using a simplified analytical theoretical model for high-frequency eddy current detection of metal pipelines i .

[0104] Specifically, according to actual detection needs, the electrical conductivity of the metal pipe is set to a variety of typical material values, including titanium alloy TC4 (0.56MS / m), stainless steel 316L (2.32MS / m), brass (15.9MS / m), aluminum alloy (20MS / m), aluminum (38MS / m) and copper (58MS / m). Then, a simplified analytical theoretical model of high-frequency eddy current detection of metal pipes is used to calculate the real part of the coil impedance change under an excitation frequency of 1MHz.

[0105] Next, according to the calculation results of the simplified model, the conductivity values ​​σ of different materials are i The corresponding real part of impedance change value real(ΔZ) is input into the fitting program to fit the mathematical relationship between the real part of impedance change and conductivity. In order to ensure the accuracy of the fitting results, the conductivity values ​​real(ΔZ) of different metal pipes are repeatedly set and the corresponding real part of impedance change is calculated successively until the data volume threshold required for fitting is met.

[0106] Once the amount of conductivity data required for fitting is met, the power function y=kx is used according to the real part formula of impedance change in step S3. -1 / 2 Fitting impedance change real part real(ΔZ i ) and the electrical conductivity σ of the metal pipe.

[0107] In a possible embodiment, the specific power function relationship obtained by fitting is:

[0108] real(ΔZ i )=11.76×σ i -0.5

[0109] The fitting results show that there is a clear inverse square root relationship between the real part of the coil impedance change and the conductivity of the metal pipe. The correlation coefficient of the fitting is as high as 0.999, indicating that the fitting results have extremely high accuracy. The calculation results are as follows: Figure 5 shown.

[0110] By comparing the calculation results of different materials, it can be seen that as the conductivity of the metal pipe increases, the real part of the coil impedance change shows a significant decreasing trend. This trend further verifies the inverse square root relationship in the theoretical formula, and also shows that the impedance change under high-frequency excitation is more sensitive to highly conductive materials.

[0111] Through the fitting process of this step, the present invention realizes a high-precision mathematical description between the real part of the impedance change and the conductivity of the metal pipeline, laying a data foundation for the subsequent rapid inversion of the conductivity. The power function relationship obtained by fitting can not only significantly simplify the calculation process, but also has extremely high reliability and is suitable for metal pipeline detection applications under various complex working conditions.

[0112] S5. Based on the coil impedance measurement results and the fitted power function curve, the actual conductivity of the metal pipe is inverted.

[0113] In the embodiment of the present application, based on the power function relationship obtained by fitting in the above steps, combined with the real part of the coil impedance change actually measured, the actual conductivity of the metal pipe is inverted and calculated. Through this step, the complex conductivity calculation process can be simplified to a fast inversion operation based on measured data and fitting function, thereby realizing efficient detection of the conductivity of the metal pipe.

[0114] In the specific implementation, first obtain the real part value of the measured coil impedance change real (ΔZ), build a high-frequency eddy current detection device under experimental conditions, set the excitation frequency to 1MHz, and apply eddy current excitation to the metal pipe. Measure the real part value of the coil impedance change ΔZ caused by the metal pipe m , a measurement that reflects the conductive properties of the pipe material.

[0115] Then, the measured real part of the coil impedance change ΔZ m Input into the power function relationship of the above fitting. Combined with the fitting function real(ΔZ i )=11.76×σ i -0.5, invert the actual conductivity of the metal pipe. The inversion formula is:

[0116] σ=11.76 / (ΔZ m 2 )

[0117] This formula can quickly and accurately convert the actual measured value into the conductivity of the metal pipe. Taking the measurement experiment with an excitation frequency of 1MHz as an example, if the measured real part of the coil impedance change is ΔZ m , substituting it into the above formula, the actual conductivity of the pipeline can be directly obtained.

[0118] In practical applications, this step not only significantly improves the efficiency of conductivity calculation by combining impedance measurement and mathematical inversion, but also ensures the reliability and accuracy of the results. Experimental verification shows that the relative error between the measured conductivity value of the metal pipeline and the standard value is controlled within 0.5% by using the detection method and device of the present invention, which can meet the high-precision detection requirements in engineering applications.

[0119] In summary, this step combines the measured data in eddy current testing with the fitted mathematical model, successfully realizing the inversion calculation from the real part of impedance change to conductivity, further verifying the operability and practical application value of this application. Through accurate conductivity inversion results, it can provide a scientific basis for the health status assessment and performance analysis of metal pipelines, and at the same time has the significant advantages of high sensitivity and rapid response.

[0120] In order to implement the above embodiment, the present application also proposes a metal pipe conductivity measurement device based on high-frequency eddy current. Figure 6 The schematic diagram of the structure of a metal pipe conductivity measurement device based on high-frequency eddy current provided in the embodiment of the present application. Figure 6 As shown, the device comprises:

[0121] The eddy current sensor design module 100 is used to design an absolute eddy current sensor. The coil of the eddy current sensor is located inside the metal pipe and is coaxially arranged with the metal pipe. A high-frequency alternating current is passed through the coil to generate eddy current in the metal pipe.

[0122] The analytical theory modeling module 200 is used to establish a simplified analytical theory model for high-frequency eddy current detection of metal pipes and set the geometric dimensions of the coil and the metal pipe;

[0123] The impedance and conductivity analysis module 300 is used to analyze the relationship between the real part of the eddy current impedance change and the conductivity of the metal pipe under high-frequency excitation according to the characteristics of the Bessel function and the spatial resolution expression;

[0124] The conductivity fitting module 400 is used to set the conductivity of the metal pipeline according to the analysis results, and input the set conductivity of the metal pipeline into the simplified analytical theoretical model of high-frequency eddy current detection of metal pipelines, and fit the relationship between the real part of impedance change and conductivity through a power function;

[0125] The conductivity inversion module 500 is used to invert the actual conductivity of the metal pipe according to the coil impedance measurement result in combination with the fitted power function curve.

[0126] In order to implement the above embodiments, the present application also proposes an electronic device, comprising: a processor, and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the method provided by the above embodiments.

[0127] In order to implement the above embodiments, the present application also proposes a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the methods provided by the above embodiments.

[0128] In order to implement the above embodiments, the present application also proposes a computer program product, including a computer program, which implements the methods provided by the above embodiments when executed by a processor.

[0129] The collection, storage, use, processing, transmission, provision and disclosure of user personal information involved in this application are in compliance with relevant laws and regulations and do not violate public order and good morals.

[0130] It should be noted that personal information from users should be collected for legitimate and reasonable purposes and should not be shared or sold outside of these legitimate uses. In addition, such collection / sharing should be carried out after receiving the user's informed consent, including but not limited to notifying the user to read the user agreement / user notice and sign the agreement / authorization including authorization of relevant user information before the user uses the function. In addition, any necessary steps should be taken to protect and safeguard access to such personal information data and ensure that others who have access to personal information data comply with its privacy policy and procedures.

[0131] The present application is expected to provide an implementation scheme for users to selectively block the use or access of personal information data. That is, the present disclosure is expected to provide hardware and / or software to prevent or block access to such personal information data. Once the personal information data is no longer needed, the risk can be minimized by limiting data collection and deleting the data. In addition, when applicable, such personal information is de-identified to protect the privacy of the user.

[0132] In the description of the aforementioned embodiments, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0133] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0134] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0135] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute the instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0136] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0137] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0138] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0139] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

[0140] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this application can be executed in parallel, sequentially or in different orders, as long as the expected results of the technical solution of this application can be achieved, and this document is not limited here.

[0141] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A method for measuring the electrical conductivity of a metal pipeline based on high-frequency eddy current, characterized in that: The following steps are involved: An absolute eddy current sensor is designed, wherein the coil of the eddy current sensor is located inside the metal pipe and is coaxially arranged with the metal pipe, and a high-frequency alternating current is passed through the coil, so that an eddy current is generated in the metal pipe; Establishing a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes, and setting the geometric dimensions of the coil and the metal pipe; According to the characteristics of Bessel function and the expression of spatial resolution, the relationship between the real part of eddy current impedance change and the conductivity of metal pipe under high frequency excitation is analyzed. The conductivity of the metal pipeline is set according to the analysis result, and the set conductivity of the metal pipeline is input into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and the relationship between the real part of the impedance change and the conductivity is fitted by a power function; According to the coil impedance measurement result, combined with the fitted power function curve, the actual conductivity of the metal pipeline is obtained by inversion.

2. The method according to claim 1, characterized in that The geometrical dimensions of the coil and the metal pipe include: the inner diameter r1 of the coil, the outer diameter r2 of the coil, the height l2-l1 of the coil, the number of turns n of the coil and the inner diameter a of the metal pipe.

3. The method according to claim 2, characterized in that The calculation expression of the simplified analytical theoretical model of high-frequency eddy current detection of metal pipes includes the impedance amplitude term Z0 determined by the coil size and the phase term S(α0) determined by the electromagnetic characteristics and size of the metal pipe. Due to the existence of the metal pipe, the expression of the coil impedance change ΔZ is: ΔZ=S(α0)Z0 Where: Where ω is the angular frequency of the excitation current, μ0 is the magnetic permeability, α0 is the spatial resolution, which is approximately calculated by the inverse of the average radius of the coil, I0 and I1 are the 0th and 1st order first-kind modified Bessel functions, K0 and K1 are the 0th and 1st order second-kind modified Bessel functions, and α1 is a complex-valued electromagnetic propagation constant.

4. The method according to claim 3, wherein the relationship between the real part of the eddy current impedance change and the conductivity of the metal pipe under high-frequency excitation is analyzed based on the characteristics of the Bessel function and the spatial resolution expression, comprising: When the excitation frequency reaches the MHz level, the following conditions are met: αK1(α1a)I0(α0a)<<α1K0(α1a)I1(α0a) and Substituting α1 into the coil impedance phase term S(α0), the approximate expression of the coil impedance phase term S(α0) is obtained as follows: At this time, the real part expression of the coil impedance change ΔZ is: The real part of the coil impedance change increases with the increase of the excitation frequency, and the real part of the impedance change is in an inverse square root relationship with the conductivity σ of the metal pipe.

5. The method according to claim 4, characterized in that The method of setting the conductivity of the metal pipeline according to the analysis result, inputting the set conductivity of the metal pipeline into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and fitting the relationship between the real part of the impedance change and the conductivity through a power function includes: According to the relationship between the real part of the eddy current impedance change under high-frequency excitation and the conductivity of the metal pipeline, the conductivity of the metal pipeline σ is set. i , and the simplified analytical theoretical model for high-frequency eddy current detection of metal pipelines is used to calculate the corresponding real part of the impedance change ΔZ i ; Determine the conductivity σ of metal pipes i Is the number of settings greater than the threshold required for fitting? If not, return to the previous step and reset the metal pipe conductivity σ i ; If it is satisfied, then according to the real part expression of impedance change, the power function y=kx -1 / 2 Fitting impedance change real part real(ΔZ i ) and the electrical conductivity σ of the metal pipe.

6. The method according to claim 5, characterized in that The actual conductivity of the metal pipe is obtained by inverting the coil impedance measurement result in combination with the fitted power function curve, including: Obtain the real part value of the actual measured coil impedance change real(ΔZ); Substitute the measurement results into the fitted power function curve and use the formula k / (ΔZ 2 ) is inverted to obtain the actual conductivity of the metal pipe.

7. A metal pipe conductivity measuring device based on high-frequency eddy current, characterized in that: include: An eddy current sensor design module is used to design an absolute eddy current sensor. The coil of the eddy current sensor is located inside the metal pipe and is coaxially arranged with the metal pipe. A high-frequency alternating current is passed through the coil to generate eddy current in the metal pipe. An analytical theoretical modeling module is used to establish a simplified analytical theoretical model for high-frequency eddy current detection of metal pipes and set the geometric dimensions of the coil and the metal pipe; Impedance and conductivity analysis module, used to analyze the relationship between the real part of eddy current impedance change and the conductivity of metal pipes under high-frequency excitation based on the characteristics of Bessel function and spatial resolution expression; A conductivity fitting module is used to set the conductivity of the metal pipeline according to the analysis results, and input the set conductivity of the metal pipeline into the simplified metal pipeline high-frequency eddy current detection analytical theoretical model, and fit the relationship between the real part of the impedance change and the conductivity through a power function; The conductivity inversion module is used to invert the actual conductivity of the metal pipeline according to the coil impedance measurement result in combination with the fitted power function curve.

8. An electronic device, characterized in that: include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a processor.

Images