CN117269613B - Dual-mode detection multi-parameter inversion method based on multi-frequency measurement grid - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
- G01B7/08—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using capacitive means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
- G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
- G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
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Abstract
The invention belongs to the technical field of electromagnetic nondestructive testing, and particularly relates to a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid. The parameter inversion method can accurately and rapidly acquire a series of parameters of the measured object through a single detection signal; and the measurement results under two frequencies can be mutually verified, so that the accuracy of the measurement results is effectively improved. The dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid comprises the following steps: simulating to obtain a first excitation frequency measurement grid; calibrating the first excitation frequency measurement grid; the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a first impedance measurement value is obtained; measuring after the lifting-off to obtain a second impedance measured value; and outputting to obtain the conductivity measurement value and the insulating layer thickness measurement value of the metal matrix in the mixed structure of the insulating-conductive type to be detected.
Description
Technical Field
The invention belongs to the technical field of electromagnetic nondestructive testing, and particularly relates to a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid.
Background
With the continuous development and the continuous deep application of the technology level, the oil pipeline with the mixed structure of the insulation type and the conduction type is widely applied in the petrochemical field. Compared with the traditional metal oil pipeline, the oil pipeline with the insulating-conducting type hybrid structure has better corrosion resistance and high temperature resistance, and has good shock resistance, flexibility and tensile property, so that the requirement of long-term stable operation under severe working condition environment can be met. It is noted that in order to achieve structural safety assessment of the above-described "insulation-conductivity" type hybrid structural oil pipeline, the skilled person needs to monitor a number of important parameters including insulation thickness, insulation dielectric constant and electrical conductivity of the metal matrix.
The existing detection technology is usually only used for detecting a specific physical parameter, and cannot realize comprehensive evaluation of the oil pipeline with the mixed structure of the insulation type and the conduction type; in addition, the method is limited by the diversity of materials of the mixed structure, the complexity of the structure and the field condition, the overall detection scheme of the oil pipeline of the mixed structure is complex in process, high in time and economic cost, and difficult to meet the requirements of engineering application. As a technical attempt to solve the above-mentioned problems, related research results show that the eddy current and capacitance dual-mode nondestructive testing technology can respectively perform defect detection and parameter test on non-conductive (weak conductive) and conductive parts in an oil pipeline with a mixed structure of an insulating-conductive type, so as to solve the problem of multi-parameter measurement of the oil pipeline with the mixed structure of the insulating-conductive type.
After further investigation, the inventors found that eddy current + capacitance dual mode non-destructive testing techniques typically require the use of a database grid to establish the correlation of lift-off or certain physical properties (conductivity or permeability) with the real and imaginary parts of the experimentally measured impedance, thereby achieving a non-linear mapping of the test signal to the measured physical parameter. The grid search is applied to replace numerical calculation required by each detection, so that the quantitative inversion speed of the eddy current and capacitance detection technology can be effectively improved.
However, the characteristics of material diversity and structural complexity of the oil pipeline with the mixed structure of the insulated-conductive type and the condition that the dual-mode detection signal is simultaneously affected by various physical parameters are limited, and it is difficult for the dual-mode detection method to directly obtain or solve specific detected physical parameters by direct measurement or inversion of a measurement grid. Therefore, it is necessary to propose a dual-mode detection multi-parameter inversion method for an oil pipeline with an insulation-conduction type hybrid structure, which can be efficiently and accurately performed.
Disclosure of Invention
The invention provides a multi-frequency measurement grid-based dual-mode detection multi-parameter inversion method, which is characterized in that the obtained detection signals are input into a pre-established multi-frequency measurement database grid for searching by combining an eddy current and capacitance dual-mode detection technology, and a series of parameters such as the thickness of an insulating layer, the dielectric constant of the insulating layer, the conductivity of a metal matrix and the like of a detected object can be accurately and rapidly obtained only through a single detection signal; and the measurement results under two frequencies can be mutually verified, so that the accuracy of the measurement results is effectively improved.
In order to solve the technical problems, the invention adopts the following technical scheme:
a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid comprises the following steps:
s101: using finite element simulation to obtain a first excitation frequency f 1 A first excitation frequency measurement grid for calculating the conductivity of the metal matrix and the thickness of the insulating layer under the condition;
s102: self-calibrating the dual-mode detection instrument based on the first excitation frequency measurement grid obtained in step S101, thereby adjusting the excitation frequency of the dual-mode detection instrument to a first excitation frequency f 1 ；
S103: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the first excitation frequency measurement grid obtained in the S101 is calibrated through the real part and the imaginary part of impedance obtained through measurement;
s104: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a first impedance measurement value is obtained; wherein the first impedance measurement is denoted (Z Re1 ，Z Im1 ）；
S105: using the first impedance measurement value (Z Re1 ，Z Im1 ) Searching a first excitation frequency measurement grid, and outputting a first parameter measurement value sigma corresponding to the first impedance measurement value 1 And h b1 ；
S106: using a calibration block to adjust the lift-off between the dual-mode detection instrument and the surface of the mixed structure of the insulating type and the conductive type to be detected, and then measuring to obtain a second impedance measured value; wherein the second impedance measurement is denoted (Z Re2 ，Z Im2 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the second impedance measurement (Z Re2 ，Z Im2 ) Searching the first excitation frequency measurement grid, and outputting a second parameter measurement value sigma corresponding to the second impedance measurement value 2 And h b2 ；
S107: for the first parameter measurement value sigma corresponding to the first impedance measurement value obtained in step S105 1 And h b1 Second parameter measurement value sigma corresponding to the second impedance measurement value obtained in step S106 2 And h b2 Inversion calculation is carried out, and a conductivity measurement value sigma and an insulation layer thickness measurement value h of the metal matrix in the mixed structure of the insulation-conduction type to be detected are obtained b 。
Further preferably, the method further comprises the following steps:
s201: using finite element simulation to obtain a second excitation frequency f 2 Conditions (conditions)A second excitation frequency measurement grid for calculating dielectric constant of the insulating layer and thickness of the insulating layer;
s202: self-calibrating the dual-mode detection instrument based on the second excitation frequency measurement grid obtained in step S201, thereby adjusting the excitation frequency of the dual-mode detection instrument to a second excitation frequency f 2 ；
S203: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the second excitation frequency measurement grid obtained in the S201 is calibrated through the real part and the imaginary part of impedance obtained through measurement;
s204: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a third impedance measurement value is obtained; wherein the third impedance measurement is denoted (Z Re3 ，Z Im3 ）；
S205: using the third impedance measurement value (Z Re3 ，Z Im3 ) Searching a second excitation frequency measurement grid, and outputting an insulating layer dielectric constant measurement epsilon and an insulating layer thickness measurement h corresponding to the third impedance measurement b ’。
Preferably, the method further comprises the following steps:
s301: inversion of the insulation layer thickness measurement h obtained in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b ' perform mutual authentication;
if the insulation layer thickness measurement h obtained by inversion in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b When the difference between' S is smaller than the preset range, the judgment step S107 is to invert the obtained conductivity measurement value sigma of the metal matrix and the insulation layer thickness measurement value h b And step S205 of inverting the obtained dielectric constant measurement epsilon and the thickness measurement h of the insulating layer b ' is a valid result; otherwise, the result is invalid.
Preferably, the inversion calculation in S107 obtains the conductivity measurement σ of the metal matrix in the mixed structure of the "insulation-conduction" type to be detected, which satisfies the following conditions:
σ=（σ 1 +σ 2 ) 2 formula (1);
the inversion calculation in S107 obtains the insulation layer thickness measurement h of the metal matrix in the mixed structure of the insulation-conduction type to be detected b The method comprises the following steps:
h b =(h b1 +h b2 -x)/2 (2), wherein x is the thickness of the calibration block.
The invention provides a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid, which comprises the following steps of: s101: using finite element simulation to obtain a first excitation frequency f 1 A first excitation frequency measurement grid for calculating the conductivity of the metal matrix and the thickness of the insulating layer under the condition; s102: self-calibrating the dual-mode detection instrument based on the first excitation frequency measurement grid obtained in step S101, thereby adjusting the excitation frequency of the dual-mode detection instrument to a first excitation frequency f 1 The method comprises the steps of carrying out a first treatment on the surface of the S103: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the first excitation frequency measurement grid obtained in the S101 is calibrated through the real part and the imaginary part of impedance obtained through measurement; s104: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a first impedance measurement value is obtained; wherein the first impedance measurement is denoted (Z Re1 ，Z Im1 ) The method comprises the steps of carrying out a first treatment on the surface of the S105: using the first impedance measurement value (Z Re1 ，Z Im1 ) Searching a first excitation frequency measurement grid, and outputting a first parameter measurement value sigma corresponding to the first impedance measurement value 1 And h b1 The method comprises the steps of carrying out a first treatment on the surface of the S106: using a calibration block to adjust the lift-off between the dual-mode detection instrument and the surface of the mixed structure of the insulating type and the conductive type to be detected, and then measuring to obtain a second impedance measured value; wherein the second impedance measurement is denoted (Z Re2 ，Z Im2 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the second impedance measurement (Z Re2 ，Z Im2 ) Searching the first excitation frequency measurement grid, and outputting a second parameter measurement value sigma corresponding to the second impedance measurement value 2 And h b2 The method comprises the steps of carrying out a first treatment on the surface of the S107: for the first parameter measurement value sigma corresponding to the first impedance measurement value obtained in step S105 1 And h b1 Second parameter measurement value sigma corresponding to the second impedance measurement value obtained in step S106 2 And h b2 Inversion calculation is carried out, and a conductivity measurement value sigma and an insulation layer thickness measurement value h of the metal matrix in the mixed structure of the insulation-conduction type to be detected are obtained b 。
Compared with the prior art, the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid has at least the following beneficial effects:
(1) The in-situ parameter measurement of the oil pipeline with the insulating-conducting type mixed structure can be realized, and the structure to be tested is not required to be destroyed for sampling;
(2) The detection and inversion of multiple parameters of the mixed structure of the insulation-conduction type to be detected can be realized by using only a single detection signal;
(3) The measuring accuracy is high, the inversion speed is high, and the measuring results under the two frequencies can be mutually verified, so that the accuracy of the measuring results is effectively improved.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the following figures:
FIG. 1 is a schematic flow chart of a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid;
FIG. 2 is a schematic diagram of the structure of the sensing element in the dual mode detector probe;
FIG. 3 is a schematic diagram of a first excitation frequency measurement grid calibrated in step S103 of the present invention;
FIG. 4 is a schematic diagram of the structure of a hybrid structural specimen of the "insulation-conductivity" type to be tested;
FIG. 5 is a schematic diagram of an impedance measurement result of a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid according to the present invention at a first excitation frequency;
FIG. 6 is a schematic diagram of a second excitation frequency measurement grid calibrated in step S203 of the present invention;
fig. 7 is a schematic diagram of an impedance measurement result of the dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid according to the present invention at a second excitation frequency.
Reference numerals:
1. a measurement region in a mixed structure sample of the "insulating-conducting" type to be detected; 2. insulating layers (plexiglas) in the mixed structure sample of the "insulating-conducting" type to be detected; 3. a metal matrix (aluminum) in a mixed structure sample of the "insulating-conducting" type to be detected; A. b, C, D, E: 5 measurement points in the mixed structure sample of the "insulation-conduction" type to be detected.
Detailed Description
The invention provides a multi-frequency measurement grid-based dual-mode detection multi-parameter inversion method, which is characterized in that the obtained detection signals are input into a pre-established multi-frequency measurement database grid for searching by combining an eddy current and capacitance dual-mode detection technology, and a series of parameters such as the thickness of an insulating layer, the dielectric constant of the insulating layer, the conductivity of a metal matrix and the like of a detected object can be accurately and rapidly obtained only through a single detection signal; and the measurement results under two frequencies can be mutually verified, so that the accuracy of the measurement results is effectively improved.
The invention provides a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid, which is shown in fig. 1 and comprises the following steps:
s101: using finite element simulation to obtain a first excitation frequency f 1 A first excitation frequency measurement grid for calculating the conductivity of the metal matrix and the thickness of the insulating layer.
It should be noted that, to facilitate understanding of the present solution by those skilled in the art, the probe model used in the finite element simulation process below is consistent with the actual probe of the dual-mode detection instrument. Specifically, the inventor further provides a probe structure of the dual-mode detection instrument as a reference. In the probe structure of the dual-mode detection instrument, the sensing element of the probe is a planar spiral coil, as shown in fig. 2. Specifically, the planar spiral coil had an inner diameter D of 1mm, a line width w of 0.2032mm (8 mil), a line spacing s of 0.0508mm (2 mil), a number of turns of 40 turns, and an outer diameter D of 21.32mm. The coil is printed on a substrate by printed circuit board technology and is connected to a test port of the dual mode detection instrument by a coaxial cable.
In a preferred embodiment of the present invention, the first excitation frequency f in step S101 1 Should be well below the resonant frequency. The real and imaginary parts of the impedance of the sensor are now insensitive to changes in the dielectric constant epsilon. Thus at excitation frequency f 1 The first excitation frequency measurement grid of the conductivity-insulating layer thickness of the metal matrix is constructed, and the influence of the dielectric constant epsilon on the grid can be ignored. For example, the technician uses the high frequency eddy current (capacitance) -low frequency eddy current dual-mode detector to measure the first excitation frequency f 1 Selected to be 1MHz.
Upon completion of step S101, step S102 is further performed.
S102: self-calibrating the dual-mode detection instrument based on the first excitation frequency measurement grid obtained in step S101, thereby adjusting the excitation frequency of the dual-mode detection instrument to a first excitation frequency f 1 。
Notably, the purpose of self-calibration is to check the various components of the system in the dual mode detection instrument, and to properly set the various parameters in the dual mode detection instrument.
Upon completion of step S102, step S103 is further performed.
S103: and (3) tightly attaching the dual-mode detection instrument to the surface of a standard test block for measurement, and calibrating the first excitation frequency measurement grid obtained in the step (S101) through the real part and the imaginary part of the impedance obtained through measurement.
Specifically, firstly, a square with a side length of 10mm is selected as a test area on the surface of the to-be-detected 'insulation-conduction' type hybrid structure, 5 times of measurement are respectively carried out on 5 points, namely, 4 corner points and a center point of the square area, and a measurement average value of the 5 points is obtained to be used as an impedance measurement value of the area (wherein the measurement method in the subsequent steps S104, S203 and S204 is the same as the method, and redundant description is omitted). Then, calibration of the first excitation frequency measurement grid is performed, as shown in fig. 3. Fig. 3 is a calibration result of step S103 of the first excitation frequency measurement grid according to the present invention.
Step S104 is further performed after step S103 is completed.
S104: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a first impedance measurement value is obtained; wherein the first impedance measurement is denoted (Z Re1 ，Z Im1 ）。
Notably, the inventors further provide a structural illustration of a hybrid structural experiment of the "insulation-conductivity" type to be tested. As shown in fig. 4, the sample of the hybrid structure of the "insulation-conduction" type to be detected is composed of plexiglas-aluminum in particular. Wherein, the upper layer (insulating layer) of the mixed structure sample is an organic glass plate, and the lower layer (metal matrix) of the mixed structure sample is an aluminum plate. The organic glass plate and the aluminum plate are both 3mm thick, and the surface of the organic glass plate has a relative dielectric constant epsilon of about 3 and the surface conductivity sigma of the aluminum plate is about 2.0X10 after preliminary test 7 S/m。
Based on the above steps, a first impedance measurement is obtained as (Z Re1 ，Z Im1 ) Is (6.88 Ω,43.45 Ω) as shown in fig. 5. Fig. 5 is a schematic diagram of an impedance measurement result of the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid provided by the invention under the first excitation frequency.
Step S105 is further performed on the basis of completion of step S104.
S105: using the first impedance measurement value (Z Re1 ，Z Im1 ) Searching a first excitation frequency measurement grid, and outputting a first parameter measurement value sigma corresponding to the first impedance measurement value 1 And h b1 。
Based on the above steps, a first parameter measurement value sigma corresponding to the first impedance measurement value (6.88 omega, 43.45 omega) is obtained 1 =2.22×10 7 S/m and h b1 =3.00mm。
Step S106 is further performed after step S105 is completed.
S106: using a calibration block to adjust the lift-off between the dual-mode detection instrument and the surface of the mixed structure of the insulating type and the conductive type to be detected, and then measuring to obtain a second impedance measured value; wherein the second impedance measurement is denoted (Z Re2 ，Z Im2 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the second impedance measurement (Z Re2 ，Z Im2 ) Searching the first excitation frequency measurement grid, and outputting a second parameter measurement value sigma corresponding to the second impedance measurement value 2 And h b2 。
Based on the above steps, a second impedance measurement value (6.94 Ω,46.59 Ω) is obtained, and the second impedance measurement value is input into the first excitation frequency measurement grid to obtain a corresponding second parameter measurement value sigma 2 =2.26×10 7 S/m and h b2 =4.02mm。
Step S107 is further performed after step S106 is completed.
S107: for the first parameter measurement value sigma corresponding to the first impedance measurement value obtained in step S105 1 And h b1 Second parameter measurement value sigma corresponding to the second impedance measurement value obtained in step S106 2 And h b2 Inversion calculation is carried out, and a conductivity measurement value sigma and an insulation layer thickness measurement value h of the metal matrix in the mixed structure of the insulation-conduction type to be detected are obtained b 。
As a preferred embodiment of the present invention, the inversion calculation in S107 obtains the conductivity measurement σ of the metal matrix in the mixed structure of the "insulation-conduction" type to be detected, which satisfies the following conditions:
σ=（σ 1 +σ 2 ) 2 formula (1);
the inversion calculation in S107 obtains the insulation layer thickness measurement h of the metal matrix in the mixed structure of the insulation-conduction type to be detected b The method comprises the following steps:
h b =(h b1 +h b2 -x)/2 (2), wherein x is the thickness of the calibration block.
Substituting the above data into the above data to obtain a metal matrix conductivity measurement sigma of 2.24X10 for the test zone 7 S/m, measurement of insulation layer thickness h b Is 3.01mm (the thickness of the calibration block is set to 1 mm), and is similar to the result of preliminary measurement.
Further, S201: using finite element simulation to obtain a second excitation frequency f 2 And a second excitation frequency measurement grid for calculating dielectric constant of the insulating layer and thickness of the insulating layer.
It should be noted that, the execution process of step S201 to step S205 and the execution process of step S101 to step S107 do not have a sequence requirement, and can be determined by the user according to the actual situation when the method is applied on site.
Wherein the second excitation frequency f is described in the step S201 2 Should be above the resonant frequency. This is because it is required that the real and imaginary parts of the sensor impedance are sensitive to changes in the dielectric constant epsilon. Thus at excitation frequency f 2 Build dielectric constant epsilon-insulating layer thickness h of insulating layer b The second excitation frequency of' measures the grid, and the impedance of the probe is measured by a dual-mode detection instrument, the dielectric constant epsilon can be obtained by inversion. For example, the technician uses the high frequency eddy current (capacitance) -low frequency eddy current dual-mode detector to measure the second excitation frequency f 2 Selected to be 10MHz.
Upon completion of step S201, step S202 is further performed.
S202: self-calibrating the dual-mode detection instrument based on the second excitation frequency measurement grid obtained in step S201, thereby adjusting the excitation frequency of the dual-mode detection instrument to a second excitation frequency f 2 。
The self-calibration process also consists in checking the various components of the system in the dual-mode detection instrument, correctly setting the various parameters in the dual-mode detection instrument.
S203: and (3) tightly attaching the dual-mode detection instrument to the surface of the standard test block for measurement, and calibrating the second excitation frequency measurement grid obtained in the step (S201) through the real part and the imaginary part of the impedance obtained through measurement.
Based on the above steps, the resulting second excitation frequency measurement grid is calibrated, as shown in fig. 6. FIG. 6 is a schematic diagram of a second excitation frequency measurement grid calibrated by the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid.
Upon completion of step S203, step S204 is further performed.
S204: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a third impedance measurement value is obtained; wherein the third impedance measurement is denoted (Z Re3 ，Z Im3 ）。
Based on the above steps, a third impedance measurement (Z Re3 ，Z Im3 ) Is (8.09 omega, -396.37 omega), as shown in fig. 7. Fig. 7 is a schematic diagram of an impedance measurement result of the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid provided by the invention under the second excitation frequency.
Upon completion of step S204, step S205 is further performed.
S205: using the third impedance measurement value (Z Re3 ，Z Im3 ) Searching a second excitation frequency measurement grid, and outputting an insulating layer dielectric constant measurement epsilon and an insulating layer thickness measurement h corresponding to the third impedance measurement b ’。
Based on the above steps, the dielectric constant measurement epsilon of the insulating layer in the test area is 3.14, and the thickness measurement h of the insulating layer is obtained b ' is 2.97mm, similar to the results of the preliminary measurement.
In a preferred embodiment of the present invention, after steps S101 to S107 and steps S201 to S205 are completed, the insulating layer thickness measurement values obtained in steps S101 to S107 and the insulating layer thickness measurement values obtained in steps S201 to S205 are further mutually verified.
Specifically, the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid further comprises the following steps:
s301: inversion of the insulation layer thickness measurement h obtained in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b ' perform mutual authentication;
if the insulation layer thickness measurement h obtained by inversion in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b When the difference between' S is smaller than the preset range, the judgment step S107 is to invert the obtained conductivity measurement value sigma of the metal matrix and the insulation layer thickness measurement value h b And step S205 of inverting the obtained dielectric constant measurement epsilon and the thickness measurement h of the insulating layer b ' is a valid result; otherwise, the result is invalid.
Taking the foregoing embodiment as an example, specifically, the foregoing calculation results in: insulation layer thickness measurement h b =3.01 mm vs. insulation layer thickness measurement h b ' 2.97mm, the relative error is about 1.34%. The relative error is far smaller than the conventional preset range (5%), so that the relative error can be judged to be smaller, and the measurement result is accurate and effective.
The dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid provided by the invention finishes the whole inversion process based on the multi-frequency measurement grid.
The invention provides a dual-mode detection multi-parameter inversion method based on a multi-frequency measurement grid, which comprises the following steps of: s101: using finite element simulation to obtain a first excitation frequency f 1 A first excitation frequency measurement grid for calculating the conductivity of the metal matrix and the thickness of the insulating layer under the condition; s102: self-calibrating the dual-mode detection instrument based on the first excitation frequency measurement grid obtained in step S101, thereby adjusting the excitation frequency of the dual-mode detection instrument to a first excitation frequency f 1 The method comprises the steps of carrying out a first treatment on the surface of the S103: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the first excitation frequency measurement grid obtained in the S101 is calibrated through the real part and the imaginary part of impedance obtained through measurement; s104: will beThe dual-mode detection instrument is tightly attached to the surface of the insulating-conducting type mixed structure to be detected for measurement, and a first impedance measurement value is obtained; wherein the first impedance measurement is denoted (Z Re1 ，Z Im1 ) The method comprises the steps of carrying out a first treatment on the surface of the S105: using the first impedance measurement value (Z Re1 ，Z Im1 ) Searching a first excitation frequency measurement grid, and outputting a first parameter measurement value sigma corresponding to the first impedance measurement value 1 And h b1 The method comprises the steps of carrying out a first treatment on the surface of the S106: using a calibration block to adjust the lift-off between the dual-mode detection instrument and the surface of the mixed structure of the insulating type and the conductive type to be detected, and then measuring to obtain a second impedance measured value; wherein the second impedance measurement is denoted (Z Re2 ，Z Im2 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the second impedance measurement (Z Re2 ，Z Im2 ) Searching the first excitation frequency measurement grid, and outputting a second parameter measurement value sigma corresponding to the second impedance measurement value 2 And h b2 The method comprises the steps of carrying out a first treatment on the surface of the S107: for the first parameter measurement value sigma corresponding to the first impedance measurement value obtained in step S105 1 And h b1 Second parameter measurement value sigma corresponding to the second impedance measurement value obtained in step S106 2 And h b2 Inversion calculation is carried out, and a conductivity measurement value sigma and an insulation layer thickness measurement value h of the metal matrix in the mixed structure of the insulation-conduction type to be detected are obtained b 。
Compared with the prior art, the dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid has at least the following beneficial effects:
(1) The in-situ parameter measurement of the oil pipeline with the insulating-conducting type mixed structure can be realized, and the structure to be tested is not required to be destroyed for sampling;
(2) The detection and inversion of multiple parameters of the mixed structure of the insulation-conduction type to be detected can be realized by using only a single detection signal;
(3) The measuring accuracy is high, the inversion speed is high, and the measuring results under the two frequencies can be mutually verified, so that the accuracy of the measuring results is effectively improved.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (3)
1. The dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid is characterized by comprising the following steps of:
s101: using finite element simulation to obtain a first excitation frequency f 1 A first excitation frequency measurement grid for calculating the conductivity of the metal matrix and the thickness of the insulating layer under the condition;
s102: self-calibrating the dual-mode detection instrument based on the first excitation frequency measurement grid obtained in step S101, thereby adjusting the excitation frequency of the dual-mode detection instrument to a first excitation frequency f 1 ；
S103: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the first excitation frequency measurement grid obtained in the S101 is calibrated through the real part and the imaginary part of impedance obtained through measurement;
s104: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a first impedance measurement value is obtained; wherein the first impedance measurement is denoted (Z Re1 ，Z Im1 ）；
S105: using the first impedance measurement value (Z Re1 ，Z Im1 ) Searching a first excitation frequency measurement grid, and outputting a first parameter measurement value sigma corresponding to the first impedance measurement value 1 And h b1 ；
S106: using a calibration block to adjust the lift-off between the dual-mode detection instrument and the surface of the mixed structure of the insulating type and the conductive type to be detected, and then measuring to obtain a second impedance measured value; wherein the second impedance measurement is denoted (Z Re2 ，Z Im2 ) The method comprises the steps of carrying out a first treatment on the surface of the Based on the second impedance measurementZ Re2 ，Z Im2 ) Searching the first excitation frequency measurement grid, and outputting a second parameter measurement value sigma corresponding to the second impedance measurement value 2 And h b2 ；
S107: for the first parameter measurement value sigma corresponding to the first impedance measurement value obtained in step S105 1 And h b1 Second parameter measurement value sigma corresponding to the second impedance measurement value obtained in step S106 2 And h b2 Inversion calculation is carried out, and a conductivity measurement value sigma and an insulation layer thickness measurement value h of the metal matrix in the mixed structure of the insulation-conduction type to be detected are obtained b ；
S201: using finite element simulation to obtain a second excitation frequency f 2 A second excitation frequency measurement grid for calculating dielectric constant of the insulating layer and thickness of the insulating layer under the condition;
s202: self-calibrating the dual-mode detection instrument based on the second excitation frequency measurement grid obtained in step S201, thereby adjusting the excitation frequency of the dual-mode detection instrument to a second excitation frequency f 2 ；
S203: the dual-mode detection instrument is tightly attached to the surface of a standard test block for measurement, and the second excitation frequency measurement grid obtained in the S201 is calibrated through the real part and the imaginary part of impedance obtained through measurement;
s204: the dual-mode detection instrument is clung to the surface of the mixed structure of the insulation type and the conduction type to be detected for measurement, and a third impedance measurement value is obtained; wherein the third impedance measurement is denoted (Z Re3 ，Z Im3 ）；
S205: using the third impedance measurement value (Z Re3 ，Z Im3 ) Searching a second excitation frequency measurement grid, and outputting an insulating layer dielectric constant measurement epsilon and an insulating layer thickness measurement h corresponding to the third impedance measurement b ’。
2. The dual mode detection multi-parameter inversion method based on multi-frequency measurement grid of claim 1, further comprising the steps of:
S301: inversion of the insulation layer thickness measurement h obtained in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b ' perform mutual authentication;
if the insulation layer thickness measurement h obtained by inversion in step S107 b The insulation layer thickness measurement h obtained by inversion of step S205 b When the difference between' S is smaller than the preset range, the judgment step S107 is to invert the obtained conductivity measurement value sigma of the metal matrix and the insulation layer thickness measurement value h b And step S205 of inverting the obtained dielectric constant measurement epsilon and the thickness measurement h of the insulating layer b ' is a valid result; otherwise, the result is invalid.
3. The dual-mode detection multi-parameter inversion method based on the multi-frequency measurement grid according to claim 1, wherein the inversion calculation in S107 obtains a measured value σ of the conductivity of the metal matrix in the mixed structure of the "insulation-conductivity" type to be detected, which satisfies the following conditions:
σ=（σ 1 +σ 2 ) 2 formula (1);
the inversion calculation in S107 obtains the insulation layer thickness measurement h of the metal matrix in the mixed structure of the insulation-conduction type to be detected b The method comprises the following steps:
h b =(h b1 +h b2 -x)/2 (2), wherein x is the thickness of the calibration block.
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