A method for constructing a pulsed eddy current probe based on finite element analysis and a storage medium

Abstract

The present invention discloses a method for constructing a pulsed eddy current probe based on finite element analysis and a storage medium, which includes obtaining a first parameter and a second parameter; based on the first parameter and the second parameter, constructing a two-dimensional axisymmetric finite element eddy current probe model through finite element analysis software; importing the finite element eddy current probe model into MATLAB software, and calculating a magnetic induction intensity amplitude data set through MATLAB software to obtain a third parameter; using the first parameter and the third parameter as a training data set, adopting a genetic algorithm, and under constraint conditions, optimizing the training data set to obtain an optimal pulsed eddy current probe; the beneficial effect of the present invention is to achieve accurate detection of defects inside the cable lead seal and defects between the lead seal and the aluminum sheath layer through the set optimal pulsed eddy current probe, and avoid the occurrence of fixed situations such as high-voltage cable insulation failure or tripping accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing of high-voltage power transmission and transformation equipment, and in particular to a method for constructing a pulsed eddy current probe based on finite element analysis and a storage medium. Background Art

[0002] High-voltage cables are key elements in the construction of urban underground energy integrated channels and offshore wind power grid connection. Cable seals, as key accessories for high-voltage cables, directly affect the safe and stable operation of high-voltage cables. If the cable seals are cracked or have internal cavities due to unqualified on-site installation quality or external factors during operation, it is easy to cause water vapor intrusion and poor cable grounding, which in turn induces high-voltage cable insulation failure or tripping accidents. Therefore, in order to ensure the service life of high-voltage cables, it is necessary to perform non-destructive testing and evaluation of the operating status of high-voltage cable seals, so as to promptly detect cable seal defects.

[0003] The nondestructive testing and evaluation technology of cable seals is a comprehensive technology that detects and evaluates the characteristic parameters such as the integrity and reliability of cable seals based on the changes in electromagnetic, ultrasonic, and radiographic signals caused by their own structure without damaging their materials and performance. At present, the nondestructive testing methods actually used for cable seal structures include ultrasonic testing, eddy current testing, radiographic testing, and loop resistance testing. However, the ultrasonic testing method requires the addition of a coupling agent between the probe and the object being tested. Due to the large curvature of the cable seal surface, there are problems such as difficulty in ultrasonic coupling and low imaging accuracy. The radiographic testing method is limited by the narrow space at the cable joint and cannot complete the complete seal flaw detection. Therefore, when the existing technical methods are used to detect the internal defects of the cable seal, the defects inside the cable seal and the defects between the seal and the aluminum sheath layer cannot be accurately detected. In severe cases, it will cause high-voltage cable insulation failure or tripping accidents.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the existing technology is used to detect internal defects of cable seals, but the defects inside the seals and between the seals and the aluminum sheath layer cannot be accurately detected, thereby causing high-voltage cable insulation failure or tripping accidents. The purpose is to provide a pulse eddy current probe construction method and storage medium based on finite element analysis, which can accurately detect defects inside the seals and between the seals and the aluminum sheath layer, avoiding the fixed situation of high-voltage cable insulation failure or tripping accidents.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for constructing a pulsed eddy current probe based on finite element analysis, the method steps comprising:

[0008] Obtain a first parameter and a second parameter, where the first parameter is a characteristic parameter of the pulsed eddy current probe to be constructed, and the second parameter is a characteristic parameter of the high-voltage cable seal.

[0009] Based on the first parameter and the second parameter, construct a two-dimensional axisymmetric finite element eddy current probe model through finite element analysis software.

[0010] Import the finite element eddy current probe model into MATLAB software, and calculate the magnetic induction intensity amplitude data set through MATLAB software to obtain a third parameter.

[0011] Take the first parameter and the third parameter as the training data set, adopt a genetic algorithm, and under constraint conditions, optimize the training data set until the eddy current detection signal at the center of the coil bottom reaches the maximum value to obtain an optimal pulsed eddy current probe.

[0012] When traditionally performing non-destructive testing on defects inside the high-voltage cable seal, ultrasonic testing method, eddy current testing method, or ray testing method is usually adopted. However, when using these methods to perform non-destructive testing on the high-voltage cable seal, it is usually impossible to accurately detect the internal defects of the cable seal and the defects between the seal and the aluminum sheath layer. The present invention provides a method for constructing a pulsed eddy current probe based on finite element analysis. By combining MATLAB and finite element analysis software, the designed pulsed eddy current probe model is optimized, realizing the accurate detection of the internal defects of the cable seal and the defects between the seal and the aluminum sheath layer through the set optimal pulsed eddy current probe, and avoiding the occurrence of fixed situations such as high-voltage cable insulation failure or tripping accidents.

[0013] Preferably, the first parameter includes the inner diameter R, coil width W, and coil height H of the excitation coil of the pulsed eddy current probe to be constructed.

[0014] Preferably, the sub-steps of constructing a two-dimensional axisymmetric finite element eddy current probe model through finite element analysis software include:

[0015] Based on the first parameter and the second parameter, construct a two-dimensional axisymmetric geometric model, and process the high-voltage cable seal with a waterproof strip wrapped on the outer surface as a lead plate with an insulating layer covering the upper surface.

[0016] According to the cable seal flaw detection standard procedure, set the spatial position of the eddy current probe to be in contact with the insulating layer on the upper surface of the lead plate.

[0017] Set the first parameter as an adjustable parameter, and set the center of the coil bottom as the observation point of the eddy current detection signal to obtain a finite element eddy current probe model.

[0018] Preferably, a spherical defect with a diameter of 1 mm is provided inside the lead plate to simulate the internal defect of the cable lead seal, and the buried depth of the groove of the defect is set as an adjustable variable D.

[0019] Preferably, the calculation sub-steps of the magnetic induction intensity amplitude data set include:

[0020] The inner diameter R of the excitation coil, the coil width W, the coil height H, and the range of the buried depth D of the groove are respectively set as [R 1 , R 2 , [W 1 , W 2 , [H 1 , H 2 , [D 1 , D 2 through MATLAB software;

[0021] The calculation step sizes of R, W, H, and D are respectively set as (R 2 - R 1 ) / n i , (W 2 - W 1 ) / n i , (H 2 - H 1 ) / n i , (D 2 - D 1 ) / n j , where n i is the step division number of the inner diameter R of the excitation coil, the coil width W, and the coil height H, and n j is the step division number of the buried depth D of the groove;

[0022] Calculate the magnetic induction intensity amplitude at different values of R, W, H, and D to obtain the magnetic induction intensity amplitude data set.

[0023] Preferably, in the finite element eddy current probe model, the specific parameters set are: the width in the r direction of the air region is set as 20W, the width in the z direction is set as 20H, the number of turns of the excitation coil is 90 turns, the amplitude of the pulsed current is 1 V, and the frequency is 32 Hz.

[0024] Preferably, the thickness of the lead plate is 12 mm, the resistivity of the lead plate is set as 2.1×10 -7 Ω·m, the thickness of the insulating layer on the upper surface of the lead plate is 5 mm, and the resistivity of the insulating layer on the upper surface of the lead plate is set as 1×10 10 Ω·m.

[0025] Preferably, the finite element analysis software is COMSOL Multiphysics software.

[0026] Preferably, the constraint conditions specifically include:

[0027]

[0028] The present invention also discloses a computer storage medium, on which a computing program is stored. When the computer program is executed by a processor, the above-mentioned method is implemented.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] A method for constructing a pulsed eddy current probe based on finite element analysis and a storage medium provided by the present invention, through the mode of combining MATLAB with finite element analysis software to optimize the designed pulsed eddy current probe model, realizes the accurate detection of defects inside the cable lead seal and defects between the lead seal and the aluminum sheath layer by the set optimal pulsed eddy current probe, and avoids the occurrence of fixed situations such as high-voltage cable insulation failure or tripping accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0032] Figure 1 Schematic diagram of the construction method DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0034] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that the present invention does not have to be practiced with these specific details. In other embodiments, well-known structures, circuits, materials or methods are not specifically described in order to avoid obscuring the present invention.

[0035] Throughout the specification, references to "one embodiment", "an embodiment", "one example" or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the phrases "one embodiment", "an embodiment", "one example" or "an example" appearing throughout the specification do not necessarily all refer to the same embodiment or example. Additionally, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art should understand that the diagrams provided herein are for illustrative purposes only and are not necessarily drawn to scale. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0036] In the description of the present invention, the orientation or positional relationship indicated by terms such as "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present invention.

[0037] Embodiment 1

[0038] This embodiment discloses a method for constructing a pulsed eddy current probe based on finite element analysis. In this embodiment, mainly by combining the finite element analysis method with MATLAB software, a model of the pulsed eddy current probe is established, and then the established model is optimized by MATLAB software. The optimal size obtained after optimization is selected to establish the corresponding pulsed eddy current probe, and the obtained probe is used to detect cable lead seal defects. The method steps include:

[0039] Obtain a first parameter and a second parameter. The first parameter is the characteristic parameter of the pulsed eddy current probe to be constructed, and the second parameter is the characteristic parameter of the high-voltage cable lead seal. The first parameter includes the inner diameter R, the coil width W, and the coil height H of the excitation coil of the pulsed eddy current probe to be constructed.

[0040] In this embodiment, in order to construct the geometric model of the pulsed eddy current probe model, the size of the pulsed eddy current probe is required to establish the corresponding model, and in the established model, the model is constructed by imitating the obtained parameters of the cable lead seal. According to the characteristic parameters of the high-voltage cable lead seal and the pulsed eddy current probe, with the goal of achieving the maximum sensitivity of the probe and detecting internal defects of the cable lead seal, the geometric size of a pulsed eddy current probe is designed and optimized.

[0041] Based on the first parameter and the second parameter, a two-dimensional axisymmetric finite element eddy current probe model is constructed by finite element analysis software;

[0042] The sub-steps of constructing a two-dimensional axisymmetric finite element eddy current probe model by finite element analysis software include:

[0043] Based on the first parameter and the second parameter, a two-dimensional axisymmetric geometric model is constructed, and the cable lead seal with a waterproof strip wrapped on the outer surface is processed into a lead plate with an insulating layer covering the upper surface;

[0044] According to the cable lead seal flaw detection standard procedure, the spatial position of the eddy current probe is set to contact the insulating layer on the upper surface of the lead plate;

[0045] The first parameter is set as an adjustable parameter, and the center of the coil bottom is set as the eddy current detection signal observation point to obtain the finite element eddy current probe model.

[0046] A spherical defect with a diameter of 1 mm is set inside the lead plate to simulate the internal defect of the cable lead seal, and the groove burial depth of the defect is set as an adjustable variable D. In the finite element eddy current probe model, the specific parameters set are: the width in the r direction in the air region is set to 20W, the width in the z direction is set to 20H, the number of turns of the excitation coil is 90 turns, the amplitude of the pulsed current is 1V, and the frequency is 32Hz; the thickness of the lead plate is 12 mm, the resistivity of the lead plate is set to 2.1×10 -7 Ω·m, the thickness of the insulating layer on the upper surface of the lead plate is 5 mm, and the resistivity of the insulating layer on the upper surface of the lead plate is set to 1×10 10 Ω·m.

[0047] The cable lead seal with a waterproof strip wrapped on the outer surface is simplified into a lead plate with an insulating layer covering the upper surface, and a two-dimensional axisymmetric geometric model is established; according to the cable lead seal flaw detection standard procedure, the spatial position of the eddy current probe is set to contact the insulating layer on the upper surface of the lead plate; the inner diameter, width, and height of the eddy current probe excitation coil are respectively set as adjustable variables R, W, and H, and the center of the coil bottom is used as the eddy current detection signal observation point.

[0048] The finite element eddy current probe model is imported into MATLAB software, and the magnetic induction intensity amplitude data set is calculated through MATLAB software to obtain the third parameter;

[0049] The calculation sub-steps of the magnetic induction intensity amplitude data set include:

[0050] The ranges of the inner diameter R of the excitation coil, the coil width W, the coil height H, and the groove burial depth D are respectively set as [R 1 , R 2 、[W 1 , W2 , [H 1 , H 2 , [D 1 , D 2 ;

[0051] Set the calculation step lengths of R, W, H, and D to (R 2 -R 1 ) / n i , (W 2 -W 1 ) / n i , (H 2 -H 1 ) / n i , (D 2 -D 1 ) / n j , where n i is the number of step segments for the inner diameter R of the excitation coil, the coil width W, and the coil height H, and n j is the number of step segments for the groove buried depth D;

[0052] Calculate the magnetic induction intensity amplitude at different values of R, W, H, and D to obtain a magnetic induction intensity amplitude dataset.

[0053] : Save the established finite element simulation model as a file with the suffix.m, and then import it into the MATLAB script program; in the MATLAB script program, set the ranges of R, W, H, and D to [R 1 , R 2 , [W 1 , W 2 , [H 1 , H 2 , and [D 1 , D 2 ; Set the calculation step lengths of R, W, H, and D to (R 2 -R 1 ) / n i , (W 2 -W 1 ) / n i , (H 2 -H 1 ) / n i , and (D 2 -D 1 ) / n j . Loop to call the imported.m finite element program to calculate the magnetic induction intensity amplitude B ij at the center of the coil bottom under different R, W, H, and D, and store the calculation results in the MATLAB preset array in sequence; for B ijUsing the values as the training set, and by means of the toolbox for constrained optimization problems based on genetic algorithms embedded in MATLAB, under the constraint condition of Solve for the optimal geometric dimensions R of the pulsed eddy current probe when the eddy current detection signal at the center of the bottom of the coil reaches the maximum value o , W o and H o .

[0054] Taking the first parameter and the third parameter as the training data set, using the genetic algorithm, and under the constraint condition, optimizing the training data set until the eddy current detection signal at the center of the bottom of the coil reaches the maximum value, to obtain the optimal pulsed eddy current probe. The obtained optimal model is that at the time of design, the optimal dimension parameters are the dimension parameters of the pulsed eddy current probe model in the actual design, and the model designed by this method can accurately detect the defects inside the cable lead seal and the defects between the lead seal and the aluminum sheath layer, avoiding the occurrence of high-voltage cable failure or tripping.

[0055] In this embodiment, the finite element analysis software set is COMSOL Multiphysics software, but it is not limited to this kind of software.

[0056] Specific implementation process:

[0057] Constructing the model: To avoid the influence of the simulation region size on the simulation accuracy, set the width in the r direction of the air region to 20W, the width in the z direction to 20H, the resistivity to 1×10 16 Ω·m, the magnetic permeability to 1; According to the relevant regulations on the thickness of the cable lead seal in the electric power industry standard DL / T 344—2010, set the thickness of the lead plate to 12mm, the width to 5W, the resistivity to 2.1×10 -7 Ω·m, the magnetic permeability to 1, set the thickness of the insulation layer on the surface of the lead plate to 5mm, the width to 5W, the resistivity to 1×10 10 Ω·m, the magnetic permeability to 1; Set a spherical defect with a diameter of 1mm inside the lead plate to simulate the defect inside the cable lead seal, and the buried depth of the spherical defect is 12mm; Set the number of turns of the excitation coil to 90 turns, and introduce a pulsed current with an amplitude of 1V and a frequency of 32Hz; Set the physical field to the magnetic field, the mesh division method to automatic division, and the solver to the default solver; Finally, save the established finite element simulation model as a MATLAB model file with the suffix.m and named 'A'.

[0058] R 1 、R 2 、W 1 、W 2 、H 1 、H2 , D 1 , D 2 , n i and n j were taken as 1 mm, 10 mm, 3 mm, 15 mm, 3 mm, 15 mm, 9 mm, 12 mm, 3, and 5 respectively, and the magnetic induction intensity amplitude B at the center of the coil bottom under different R, W, H, and D was calculated. ij The B ij values (a total of 4×5×5×6 = 600 groups of data) under different R, W, H, and D were used as the training set, and the genetic algorithm was used to fit the sum of the eddy current detection signals at the center of the coil bottom, that is, the sum of the magnetic induction intensity amplitudes, and it was obtained that it is proportional to and further, by solving for R, W, and H when it takes the maximum value, the optimal geometric dimensions R o , W o and H o of the pulsed eddy current probe were 10 mm, 15 mm, and 15 mm respectively.

[0059] A method for constructing a pulsed eddy current probe based on finite element analysis disclosed in this embodiment realizes accurate detection of defects inside the cable lead seal and defects between the lead seal and the aluminum sheath layer through an optimal pulsed eddy current probe set by optimizing the designed pulsed eddy current probe model in a manner of combining MATLAB with finite element analysis software, avoiding the occurrence of fixed situations such as high - voltage cable insulation failure or tripping accidents.

[0060] Embodiment 2

[0061] This embodiment discloses a computer storage medium on which a calculation program is stored. When the computer program is executed by a processor, the method described in Embodiment 1 is implemented.

[0062] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer - usable storage media (including but not limited to disk memories, CD - ROMs, optical memories, etc.) containing computer - usable program codes.

[0063] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program issued instructions. These computer program issued instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the issued instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 means for realizing the functions specified in one or more blocks or multiple blocks.

[0064] These computer program issued instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the issued instructions stored in the computer-readable memory generate a manufactured article including the issued instruction means, and the issued instruction means realizes the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 means for realizing the functions specified in one or more blocks or multiple blocks.

[0065] These computer program issued instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the issued instructions executed on the computer or other programmable device provide steps for realizing the functions specified in the Figure 1 one or more flows and / or blocks Figure 1 means for realizing the functions specified in one or more blocks or multiple blocks.

[0066] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing a pulsed eddy current probe based on finite element analysis, characterized in that, the method steps include: obtaining a first parameter and a second parameter, where the first parameter is a characteristic parameter of the pulsed eddy current probe to be constructed, and the second parameter is a characteristic parameter of the high-voltage cable lead seal; based on the first parameter and the second parameter, constructing a two-dimensional axisymmetric finite element eddy current probe model through finite element analysis software; importing the finite element eddy current probe model into MATLAB software, and calculating a magnetic induction intensity amplitude data set through MATLAB software to obtain a third parameter; using the first parameter and the third parameter as a training data set, adopting a genetic algorithm, and under constraint conditions, optimizing the training data set until the eddy current detection signal at the center of the coil bottom reaches the maximum value to obtain an optimal pulsed eddy current probe; Among them, the inner diameter, coil width, and coil height of the pulsed eddy current probe are used as the characteristic parameters of the pulsed eddy current probe. The cable lead seal is processed into a lead plate with an insulating layer covering the upper surface and a spherical defect inside. The lead plate thickness, resistivity, insulating layer thickness, insulating layer resistivity, and defect size are used as the characteristic parameters of the high-voltage cable lead seal. Based on the above two sets of parameters, a two-dimensional axisymmetric geometric model is constructed. The space of the eddy current probe is set to contact the insulating layer on the upper surface of the lead plate. The characteristic parameters of the pulsed eddy current probe are set as adjustable parameters, and the center of the coil bottom is set as the observation point of the eddy current detection signal to obtain a finite element eddy current probe model; the ranges of the inner diameter R, coil width W, coil height H, and groove burial depth D of the excitation coil are respectively set as [R 1 , R 2 , [W 1 , W 2 , [H 1 , H 2 , [D 1 , D 2 through MATLAB software. The calculation step sizes of R, W, H, and D are respectively set as (R 2 - R 1 ) / n i , (W 2 - W 1 ) / n i , (H 2 - H 1 ) / n i , (D 2 - D 1 ) / n j , where n i is the number of step segments for the inner diameter R of the excitation coil, coil width W, and coil height H, and n j is the number of step segments for the groove burial depth D. Calculate the magnetic induction intensity amplitude at different values of R, W, H, and D to obtain a magnetic induction intensity amplitude dataset; the specific constraints for data optimization using the genetic algorithm are: 。 2. The method for constructing a pulsed eddy current probe based on finite element analysis according to claim 1, characterized in that, a spherical defect with a diameter of 1 mm is arranged inside the lead plate to simulate the internal defect of the cable lead seal, and the groove burial depth of the defect is set as an adjustable variable D.

3. The method for constructing a pulsed eddy current probe based on finite element analysis according to claim 1, characterized in that, in the finite element eddy current probe model, the specific parameters set are: the width in the r direction in the air region is set to 20W, the width in the z direction is set to 20H, the number of turns of the excitation coil is 90 turns, the amplitude of the pulsed current is 1V, and the frequency is 32Hz.

4. The method for constructing a pulsed eddy current probe based on finite element analysis according to claim 1, characterized in that, The thickness of the lead plate is 12 mm, and the resistivity of the lead plate is set to 2.1×10 -7 Ω·m. The thickness of the insulating layer on the upper surface of the lead plate is 5 mm, and the resistivity of the insulating layer on the upper surface of the lead plate is set to 1×10 10 Ω·m.

5. The method for constructing a pulsed eddy current probe based on finite element analysis according to any one of claims 1 to 4, characterized in that, the finite element analysis software is COMSOL Multiphysics software.

6. A computer storage medium, on which a computer program is stored, characterized in that, when the computer program is executed by a processor, the method as described in any one of claims 1 to 4 is implemented.

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