Flexible array eddy current multi-parameter detection system and method for natural gas pipeline

Abstract

The invention relates to the technical field of safety detection of a natural gas pipeline in a natural gas pipe gallery, in particular to a flexible array eddy current multi-parameter detection system and method for the natural gas pipeline, and the system comprises an upper computer, an excitation module, an array probe, a collection module and a power supply module detection method for providing a working power supply for the excitation module and the collection module. The method comprises the following specific steps: step 1, initializing a system and installing a probe; step 2, setting detection parameters; step 3, real-time monitoring and signal acquisition; 4, acquiring and storing a reference signal; step 5, differential signal extraction; step 6, establishing a calibration curve; 7, analyzing and calculating parameters; and step 8, displaying a result. Step 9, retesting the key area; the flexible excitation coil and the four groups of detection coils are adopted, so that the system is very suitable for pipeline curved surface detection, settlement, displacement, crack defects, weld defects and coating thickness measurement are realized at the same time, equipment redundancy and operation cost are reduced, and the system is simple in structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural gas pipeline safety detection in natural gas pipeline gallery, in particular to a flexible array eddy current multi-parameter detection system and method for natural gas pipeline. BACKGROUND

[0002] The energy pipeline area in the gallery has large span and wide service area. In the long-term operation process, the pipeline is affected by factors such as line curvature, thermal expansion and contraction, uneven settlement of the gallery body, and other comprehensive working conditions. The pipeline bears the coupling effect of multiple loads such as heat and force. Stress concentration is easy to occur at positions such as the intersection of main and branch galleries, tee joint, and pipeline support. When the concentrated stress exceeds the limit of the pipeline material, pipeline rupture may occur, which may cause gallery leakage, fire, explosion and other accidents. For some parts of the pipeline that have already produced phenomena such as pipeline cross failure and horizontal displacement, if the pipeline stress condition cannot be monitored and the stress state cannot be evaluated in time, the pipeline operation safety will be seriously threatened. At present, the detection of natural gas pipelines mostly uses ultrasonic, magnetic powder or traditional eddy current technology. However, these methods usually only detect a single parameter such as surface defects, and it is difficult to realize integrated measurement of settlement, displacement, defects and non-conductive coating thickness. SUMMARY

[0003] In order to solve the above problems, the present application provides a flexible array eddy current multi-parameter detection system and method for natural gas pipeline.

[0004] A multifunctional flexible coil eddy current system for safety detection of natural gas pipeline, comprising a host computer, further comprising an excitation module connected with the host computer for generating a specific frequency sinusoidal excitation signal, an array probe connected with the excitation module through a cable, a collection module connected with the array probe through a probe interface for collecting an induced voltage signal, and a power supply module for providing working power for the excitation module and the collection module. The array probe comprises an excitation coil and four groups of detection coils, which are arranged in a specific array around the excitation coil.

[0005] A detection method of a multifunctional flexible coil eddy current system for safety detection of natural gas pipeline, the specific steps are as follows: Step 1, system initialization and probe installation: before pipeline monitoring, the detection coils of the array probe are tightly attached to the sensitive parts to be measured on the outer wall of the pipeline through the pipeline support; if settlement or displacement monitoring is performed, first, the fixed connection between the excitation coil and the detection coil is released, the detection coil is fixed to one end of the joint support, the other end of the joint support is fixed to the outer wall of the pipeline, and the excitation coil assembly is installed on the adjacent fixed pile; Step 2, detection parameter setting: through the parameter setting interface of the host computer, the output parameters of the excitation module and the sampling parameters of the collection module are set: Excitation parameters: Select the type, frequency, and amplitude of the excitation signal according to the detection target. When detecting surface defects, pipe settlement, displacement, or non-conductive coating thickness, a high-frequency sinusoidal excitation signal is selected, with a frequency range of 100kHz - 400kHz and an amplitude of ±5V. When detecting internal defects, a low-frequency sinusoidal excitation signal should be selected, with a frequency range of 10kHz - 50kHz and an amplitude of ±5V. The specific frequency should be optimized based on different materials. The selection method is as follows: High-frequency optimization: Compare the rate of change of signal amplitude of a 1mm deep surface defect at different frequencies, and select the frequency with the highest rate of change; Low-frequency optimization: Compare the rate of change of signal amplitude of a 1mm buried defect at different frequencies, and select the frequency with the highest rate of change; Acquisition parameters: Set the sampling frequency of the acquisition module to no less than 1MHz, select synchronous triggering of the excitation signal, and ensure the phase consistency of the signal acquisition; Step 3, Real-time Monitoring and Signal Acquisition: The system is started for real-time monitoring. The excitation module applies a set sinusoidal excitation signal to the excitation coil of the array probe, and simultaneously induces a voltage signal in the detection coil. The acquisition module synchronously acquires the real-time signal V from each detection coil. t ; Step 4, Reference Signal Acquisition and Storage: Place the array probe in a reference area of ​​the pipe under test that is free of defects, coatings, settlement, and displacement, and acquire the induced voltage signal of each detection coil as its respective reference signal V. ref ; Step 5: Differential signal extraction: Perform the same filtering and denoising process on the acquired real-time signal Vt as on the reference signal, and then extract the processed real-time signal Vt. t With the stored reference signal V ref Subtracting them, we obtain the real-time differential signal ΔV (ΔV = V). t -V ref ); Step 6: Calibration Curve Establishment: Before the formal measurement, the system needs to establish a measurement calibration curve on the standard test block. Defect depth calibration: On a calibration block containing a series of known depths, such as 0.5, 1.0, 2.0, and 3.0 mm of artificial defects, the differential signal ΔV of the detection coil is collected to establish a database and fitting curve of "defect depth - differential signal ΔV". Lift-off distance calibration: By precisely changing the distance between the probe and the surface of the test block, i.e. lifting, different lifting amounts, such as differential signals ΔV from 0.1mm to 3mm, are collected to establish the corresponding relationship curve of "lift-off distance - differential signal ΔV". Vertical settlement / horizontal displacement calibration: on the experimental device, simulate the vertical settlement or horizontal displacement of the pipeline relative to the fixed pile, record the corresponding relationship between the displacement amount and the differential signal, and establish a "vertical settlement / horizontal displacement amount-differential signal AV" curve; Step 7, parameter analysis and calculation: according to the characteristics of the differential signal, combined with the pre-stored calibration curve, multi-parameter calculation is carried out: Internal defect identification and quantification: analyze the differential signal under low-frequency excitation: extract the differential signal AV, query the "defect depth-differential signal amplitude AV" calibration curve, and calculate the equivalent depth of the defect; Non-conductive coating thickness measurement: analyze the differential signal AV under high-frequency excitation: since the non-conductive coating does not affect the eddy current field, the thickness change is equivalent to the lift-off change, according to the real-time differential signal AV, query the "lift-off distance-differential signal AV" calibration curve, and convert the thickness value of the coating; Settlement and displacement calculation: in the settlement / displacement monitoring mode, analyze the attenuation degree of the signal amplitude, and calculate the actual settlement height or horizontal displacement distance of the pipeline according to the "vertical settlement / horizontal displacement amount-differential signal AV" calibration curve from the signal amplitude drop; Step 8, result display: the defect depth, coating thickness, displacement and other parameters calculated by the host computer software are displayed in the form of a data list in real time; Step 9, retest of key areas: if abnormal signals are found in the monitoring process, dense collection or continuous monitoring with higher sampling frequency can be carried out for the specific detection line corresponding to the area through software control, so as to realize accurate positioning and detailed evaluation of local key parts of the pipeline.

[0006] The step S8 displays the pipeline profile in the form of a two-dimensional or three-dimensional diagram, and superimposes the measurement results such as defect position and settlement area on the diagram in different colors or marks.

[0007] The present application has the advantages that: the flexible excitation coil and four sets of detection coils are very suitable for pipeline curved surface detection, and can realize settlement, displacement, crack defect, weld defect and coating thickness measurement, reduce equipment redundancy and operation cost, the system structure is simple, and is suitable for on-site pipeline monitoring, and through calibration curve and software processing, rapid and accurate data analysis is realized. BRIEF DESCRIPTION OF DRAWINGS

[0008] The present application will be further described below in combination with the drawings and examples.

[0009] Figure 1 It is a schematic block diagram of the hardware connection of the present application; Figure 2 It is a schematic diagram of the probe installation for measuring the settlement of the pipeline of the present application; Figure 3 A flow chart of the detection method of the present application; Figure 4 A calibration curve example of the present application; Figure 5 An array probe structure diagram of an embodiment of the present application; Figure 6 A "surface defect depth-differential signal (ΔV)" fitting curve diagram of an embodiment of the present application; Figure 7 A "lift-off distance-differential signal (ΔV)" fitting curve diagram of an embodiment of the present application; Figure 8 A "vertical settlement / horizontal displacement amount-differential signal (ΔV)" fitting curve diagram of an embodiment of the present application; Figure 9 A probe installation diagram for measuring pipeline displacement of the present application; The figure mark: 1, pipeline outer wall; 2, pipeline support; 3, array support; 4, excitation coil; 5, detection coil; 6, fixed pile. DETAILED DESCRIPTION

[0010] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below.

[0011] As shown in Figures 1 to 4 , Figure 9 A multi-functional flexible coil eddy current system for natural gas pipeline safety detection, comprising a host computer, further comprising an excitation module connected with the host computer for generating a specific frequency sine excitation signal, an array probe connected with the excitation module through a cable, a collection module connected with the array probe through a probe interface for collecting an induced voltage signal, and a power supply module for providing working power for the excitation module and the collection module. The array probe comprises an excitation coil 4 and four groups of detection coils 5. The flexible excitation coil 4 and the four groups of detection coils 5 are very suitable for pipeline curved surface detection, and can realize settlement, displacement, crack defect, weld defect and coating thickness measurement, reduce equipment redundancy and operation cost, and the system structure is simple, suitable for on-site pipeline monitoring, and through calibration curve and software processing, fast and accurate data analysis is realized.

[0012] The detection coils 5 are arranged in a specific array form around the excitation coil 4, and the specific array form of the detection coils 5 is staggered distribution, symmetric distribution, etc., and is processed in the form of flexible printed circuit board, which has good curved surface fitting capability.

[0013] The host computer communicates with the collection module through a data interface, the data interface is USB or Ethernet, and receives and processes data.

[0014] The acquisition module is connected with the detection coil 5 of the array probe through the probe interface, and is used for acquiring an induced voltage signal.

[0015] The acquisition module is an oscilloscope or an acquisition card with high precision, and a sampling rate is greater than or equal to 1 MHz, so as to ensure the accuracy and real-time performance of signal acquisition.

[0016] The excitation coil 4 is arranged above, and the detection coil 5 is located below the center of the excitation coil 4. By default, the excitation coil 4 and the detection coil 5 are fixedly connected, that is, the excitation coil 4 and the detection coil 5 are in a fixed connection state by default.

[0017] The excitation module is a signal generator, which can output a sine signal with a frequency range of 1 Hz-450 kHz and an amplitude of ±5 V. The frequency and amplitude can be set through the LabVIEW signal processing software built in the upper computer, so as to adapt to different detection requirements.

[0018] The upper computer is built in with LabVIEW signal processing software, and has functions of data analysis, curve calibration, parameter calculation and result output.

[0019] The array probe emits an excitation magnetic field to the workpiece, and the workpiece reflects an induced magnetic field to the array probe.

[0020] A detection method of a multifunctional flexible coil eddy current system for natural gas pipeline safety detection, and the specific steps are as follows: Step 1, system initialization and probe installation: before pipeline monitoring, the detection coil 5 of the array probe is tightly attached to the sensitive part to be detected of the pipeline outer wall 1 through the pipeline support 2; if settlement or displacement monitoring is performed, the fixed connection between the excitation coil 4 and the detection coil 5 is first released, as shown in Figure 2 Fig. Figure 9 The detection coil 5 is fixed to one end of the joint support 3, the other end of the joint support 3 is fixed to the pipeline outer wall 1, and the excitation coil 4 assembly is installed on the adjacent fixed pile 6, so that the detection coil 5 is located directly below the excitation coil 4 in the initial state, and the distance between the two is a preset initial value, such as zero distance or a calibration distance. When the pipeline settlement or displacement is detected, only one detection coil can be selected because a too large range does not need to be covered. Step 2, detection parameter setting: the output parameters of the excitation module and the sampling parameters of the acquisition module are set through the parameter setting interface of the upper computer. Excitation parameters: the type, frequency and amplitude of the excitation signal are selected according to the detection target: When surface defects, pipeline settlement, displacement or non-conductive coating thickness are detected, a high-frequency sinusoidal excitation signal is selected, the frequency range is 100 kHz-400 kHz, and the amplitude is ±5 V. When detecting internal defects, a low-frequency sinusoidal excitation signal is selected, with a frequency range of 10 kHz - 50 kHz and an amplitude of ±5V. The specific frequency should be optimized for testing different materials, and the selection method is as follows: High frequency optimization: Compare the signal amplitude variation rate of 1 mm deep surface defects at different frequencies, and select the frequency with the highest variation rate; Low frequency optimization: Compare the signal amplitude variation rate of 1 mm deep defects at different frequencies, and select the frequency with the highest variation rate; Acquisition parameters: Set the sampling frequency of the acquisition module to not less than 1 MHz, select the excitation signal synchronous trigger to ensure the consistency of the signal acquisition phase; Step 3, real-time monitoring and signal acquisition: Start the system for real-time monitoring, and apply the set sinusoidal excitation signal to the excitation coil 4 of the array probe, while inducing a voltage signal in the detection coil 5, and the acquisition module synchronously acquires the real-time signal V t of each detection coil 5; Step 4, reference signal acquisition and storage: Place the array probe in the defect-free, coating-free, sediment-free, and displacement-free reference area of the measured pipeline, and acquire the induced voltage signal of each detection coil 5 at this time as the respective reference signal V ref . Perform digital filtering on the reference signal, such as bandpass filtering, to eliminate power frequency noise and environmental interference, and store the processed signal in the upper computer; Step 5, differential signal extraction: Perform the same filtering and noise reduction processing on the acquired real-time signal V t as the reference signal, subtract the processed real-time signal V t from the stored reference signal V ref , and obtain the real-time differential signal ΔVΔV= V t -V ref . This differential signal effectively eliminates common mode noise such as pipeline material, environmental electromagnetic interference, and highlights the signal changes caused by defects, coatings, or displacement. Step 6, calibration curve establishment: Before formal measurement, the system needs to establish a measurement calibration curve on the standard test block: Defect depth calibration: On the calibration test block containing a series of known depths, such as 0.5, 1.0, 2.0, and 3.0 mm artificial defects, collect the differential signal ΔV of the detection coil 5, and establish a "defect depth-differential signal ΔV" database and fitting curve; lift-off distance calibration: By accurately changing the distance between the probe and the test block surface, i.e. lift-off, collect the differential signal ΔV under different lift-off amounts, such as 0.1 mm to 3 mm, and establish a "lift-off distance-differential signal ΔV" corresponding relationship curve, which will be directly used for non-conductive coating thickness measurement; Vertical settlement / horizontal displacement calibration: On the experimental device, simulate the vertical settlement or horizontal displacement of the pipeline relative to the fixed pile 6, record the corresponding relationship between the displacement amount and the differential signal, establish the "vertical settlement / horizontal displacement amount-differential signal AV" curve, and measure the probe installation mode of the pipeline settlement or displacement as shown in Figure 2 Since the excitation coil 4 and the detection coil 5 are simultaneously horizontal or vertical, the calibration curve can be universal; Step 7, parameter analysis and calculation: According to the characteristics of the differential signal, combined with the pre-stored calibration curve, multi-parameter calculation is carried out: Internal defect identification and quantification: Analyze the differential signal under low-frequency excitation: extract the differential signal AV, query the "defect depth-differential signal amplitude AV" calibration curve, and calculate the equivalent depth of the defect; Non-conductive coating thickness measurement: Analyze the differential signal AV under high-frequency excitation: since the non-conductive coating does not affect the eddy current field, its thickness change is equivalent to the lift-off change, according to the real-time differential signal AV, query the "lift-off distance-differential signal AV" calibration curve, and convert the thickness value of the coating; Settlement and displacement calculation: In the settlement / displacement monitoring mode, analyze the degree of signal amplitude attenuation, and according to the "vertical settlement / horizontal displacement amount-differential signal AV" calibration curve, calculate the actual settlement height or horizontal displacement distance of the pipeline from the signal amplitude drop; Step 8, result display: use the host computer software, such as LabVIEW or custom application data processing and display functions: Real-time display of calculated defect depth, coating thickness, displacement and other parameters in the form of a data list; Step 9, key area retest: If abnormal signals are found in a certain area during monitoring, the software can be used to control the specific detection coil 5 corresponding to the area to perform intensive collection or continuous monitoring at a higher sampling frequency, achieving precise positioning and detailed evaluation of local key parts of the pipeline.

[0021] The step S8 displays the pipeline profile in the form of a two-dimensional or three-dimensional diagram, and superimposes the measurement results such as defect position and settlement area on the diagram in different colors or marks, realizes the visualization of the detection results, generates a detection report containing all measurement parameters, timestamps and position information, and stores it as a universal file format such as TXT, CSV.

[0022] Embodiment: As shown in Figure 1 , Figures 5 to 8 The implementation environment and object: Use equipment: prepare a host computer installed with LabVIEW or custom application software, Figure 5The flexible array probe, RIGOL DG1032 signal generator, Hantek DSO 3254 USB virtual oscilloscope and stabilized power supply are shown in the system structure as Figure 1 shown. Experimental environment: laboratory environment.

[0023] The measured object: a section of X52 steel natural gas pipeline with a diameter of 300 mm, the outer wall of the pipeline has 4.0, 2.0, 1.0, 0.5 mm deep surface groove defects; a section of the middle area of the pipeline is coated with an uneven thickness epoxy resin anticorrosive coating, the actual thickness is between 1.2 mm and 2 mm; Comprehensive detection process: Step 1, system initialization and probe installation: the structure of the selected flexible array probe is shown as Figure 5 shown. The probe is set as follows: 1. Defect detection and non-conductive coating thickness detection: the detection coil 5 of the probe is tightly attached to the measured area of the pipeline outer wall; 2. Non-conductive coating thickness detection: simulate the non-conductive coating with A4 paper and place it between the test piece and the detection coil 5; 3. Vertical settlement / horizontal displacement monitoring: remove the fixed connection device of the excitation coil 4 and the detection coil 5 of the probe, as Figure 2 shown, fix the detection coil 5 at one end of the assembled support 3, connect the excitation coil 4 with the fixed stake 6, and adjust the interval A4 paper thickness to simulate the settlement / displacement amount; Step 2, detection parameter setting: set the parameters through the software interface of the upper computer: Excitation parameters: set two excitation modes for switching: Mode one, for surface defects, coating, settlement and displacement: frequency 120 kHz, amplitude ± 5V; Mode two, for internal defects: frequency 18 kHz, amplitude ± 5V; Step 3, real-time monitoring and signal acquisition: move the array probe to the measured area, click run, start the "continuous monitoring" mode of the software, and the system automatically adjusts the sampling rate to match the current detection frequency, and displays the waveforms of the detection signals of each channel on the front panel in real time; Step 4, reference signal acquisition and storage: place the array probe in the reference calibration area, click the "acquire reference signal" command in the upper computer software, the system acquires the signals of all detection coils 5, and the software automatically filters and denoises these signals, and stores them as the reference signals V ref of each channel, the reference calibration area of each detection quantity is selected as follows: 1. Defect detection: use the defect-free position as the reference to calibrate the area; 2. Non-conductive coating thickness detection: use the non-coating position as the reference to calibrate the area; 3. Vertical settlement / horizontal displacement monitoring: use the position where the excitation coil 4 and the detection coil 5 are closely attached as the reference to calibrate the area; Step 5, signal processing and difference calculation: process the collected real-time signal V t in the same way as the reference signal. Subtract the processed real-time signal V t from the stored reference signal V ref to obtain the real-time difference signal ΔV ΔV = V t - V ref , and use the difference signal as the defect characteristic signal; Step 6, calibration curve establishment: before formal detection, the calibration curve of each detection quantity needs to be established. The establishment scheme of each detection quantity calibration curve is as follows: Defect calibration: taking the pipe outer wall surface defect as an example, on the calibration test piece containing a series of depths of 4.0, 2.0, 1.0, and 0.5 mm surface defects, use 120 kHz, ±5V excitation, and place the detection coil 5 of the probe closely against the defect-free area. At this time, the difference signal ΔV is between ±0.25mV, and the noise interference is within a reasonable range. Then move the detection coil 5 to the center of each defect position, and perform secondary fitting on the data in the record table to obtain the "surface defect depth-difference signal (ΔV)" fitting curve. Taking No. 2 detection coil 5 as an example, its "surface defect depth-difference signal (ΔV)" fitting curve is shown in Figure 6 ; Lift-off distance calibration: use 120 kHz, ±5V excitation, initially place the detection coil 5 of the probe closely against the non-coating area of the calibration test piece, and change the lift-off distance between the detection coil 5 and the calibration test piece within the range of 0 to 3 mm with a step of 0.1 mm. For curved test pieces, use non-metallic spacers (such as A4 paper, adhesive tape) to ensure that the lift-off distances of the detection coil 5 at each position are the same. Record the difference signal (ΔV) after each step, and perform secondary fitting on the data in the record table to obtain the "lift-off distance-difference signal (ΔV)" fitting curve. Taking No. 2 detection coil 5 as an example, its "lift-off distance-difference signal (ΔV)" fitting curve is shown in Figure 7 ; Vertical settlement / horizontal displacement calibration: remove the fixed connection between the probe excitation coil 4 and the detection coil 5. Keep the excitation coil 4 and the detection coil 5 coaxial, use 120 kHz, ±5V excitation, initially tightly adhere the excitation coil 4 and the detection coil 5, through the precision displacement table, change the interval distance between the excitation coil 4 and the detection coil 5 in the range of 0 to 3 mm with 0.1 mm as the step, record the differential signal (ΔV) after each step, perform quadratic fitting on the data in the record table, obtain the "vertical settlement / horizontal displacement amount-differential signal (ΔV)" fitting curve, and obtain the "vertical settlement / horizontal displacement amount-differential signal (ΔV)" fitting curve. Take No. 2 detection coil 5 as an example, the "vertical settlement / horizontal displacement amount-differential signal (ΔV)" fitting curve is as shown in Figure 8 Step 7, multi-parameter analysis and calculation: for each detection quantity, select the corresponding calibration curve for calculation, and the detection cases of each detection quantity are as follows: Defect detection: using 120 kHz, ±5V excitation, the detection coil 5 is tightly adhered to the surface of the test piece, and the differential signal ΔV is 34.36, 16.45, 6.8 and 2.94 mV in turn when passing through the surface defect positions with actual depths of 4.0, 2.0, 1.0 and 0.5 mm in turn, and the defect depth can be calculated by indexing the calibration curve; Non-conductive coating thickness measurement: the experimental environment is the same as that in step 6 for establishing the calibration curve, 120 kHz, ±5V excitation is used, and A4 paper is used to simulate the non-conductive coating. Since the non-conductive coating itself does not affect the eddy current field, the lift-off distance is the coating thickness. Take No. 2 detection coil 5 as an example, when the thickness of the A4 paper is 0.5, 1.2, 1.8 and 2.5 mm in turn, the differential signal ΔV is 34.06, 66.03, 87.38 and 106.36 mV in turn, and the coating thickness can be calculated by indexing the calibration curve. When the coating thickness is less than 1 mm, the ΔV changes more than 4 mV for every 0.1 mm change; Settlement amount detection: the experimental environment is the same as that in step 6 for establishing the calibration curve, 120 kHz, ±5V excitation is used, and A4 paper is used to simulate the non-conductive coating. Since the non-conductive coating itself does not affect the eddy current field, the lift-off distance is the coating thickness. Take No. 2 detection coil 5 as an example, when the thickness of the A4 paper is 0.5, 1.2, 1.8 and 2.5 mm in turn, the differential signal ΔV is 34.06, 66.03, 87.38 and 106.36 mV in turn, and the coating thickness can be calculated by indexing the calibration curve. When the coating thickness is less than 1 mm, the ΔV changes more than 4 mV for every 0.1 mm change; Step 8, result display: click data save, and the host computer software lists the defect depth, coating thickness and settlement amount of all measurement points in table form.

[0024] ​The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A flexible array vortex multi-parameter detection system for natural gas pipeline, comprising a host computer, characterized in that: It also includes an excitation module connected with the host computer for generating a specific frequency sine excitation signal, an array probe connected with the excitation module through a cable, a collection module connected with the array probe through a probe interface for collecting induced voltage signals, and a power supply module for providing working power for the excitation module and the collection module. The array probe includes an excitation coil (4) and four groups of detection coils (5) arranged in a specific array around the excitation coil (4).

2. A flexible array eddy current multi-parameter sensing system for natural gas pipelines according to claim 1, characterized in that: The specific array form of the detection coil (5) is staggered distribution, symmetric distribution, etc.

3. A flexible array eddy current multi-parameter sensing system for natural gas pipelines according to claim 1, characterized in that: The host computer communicates with the collection module through a data interface.

4. A flexible array eddy current multi-parameter sensing system for natural gas pipelines according to claim 1, characterized in that: The collection module is an oscilloscope or a collection card with a sampling rate of ≥1MHz.

5. A flexible array eddy current multi-parameter sensing system for natural gas pipelines as defined in claim 1, wherein: The excitation coil (4) is arranged above, and the detection coil (5) is located below the center, and the excitation coil (4) and the detection coil (5) are fixedly connected by default.

6. A flexible array eddy current multi-parameter sensing system for natural gas pipelines according to claim 1, characterized in that: The excitation module is a signal generator with an output frequency range of 1Hz-450kHz and a sine signal amplitude of ±5V.

7. A flexible array eddy current multi-parameter sensing system for natural gas pipelines as defined in claim 1, wherein: The host computer is built-in based on LabVIEW signal processing software.

8. A flexible array eddy current multi-parameter sensing system for natural gas pipelines according to claim 1, characterized in that: The array probe emits an excitation magnetic field to the workpiece, and the workpiece reflects an induced magnetic field to the array probe.

9. A method of detection using a flexible array vortex multi-parameter detection system for natural gas pipelines according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: Step 1, system initialization and probe installation: before pipeline monitoring, the detection coil (5) of the array probe is tightly attached to the measured sensitive part of the pipeline outer wall (1) through the pipeline support (2); if settlement or displacement monitoring is performed, first, the fixed connection between the excitation coil (4) and the detection coil (5) is released, the detection coil (5) is fixed to one end of the joint support (3), the other end of the joint support (3) is fixed to the pipeline outer wall (1), and the excitation coil (4) assembly is installed on the adjacent fixed pile (6); Step 2, detection parameter setting: set the output parameters of the excitation module and the sampling parameters of the collection module through the parameter setting interface of the host computer: Excitation parameters: select the type, frequency and amplitude of the excitation signal according to the detection target: When detecting surface defects, pipeline settlement, displacement or non-conductive coating thickness, select a high-frequency sine excitation signal with a frequency range of 100kHz-400kHz and an amplitude of ±5V; When detecting internal defects, select a low-frequency sine excitation signal with a frequency range of 10kHz-50kHz and an amplitude of ±5V, and the specific frequency should be optimized according to different materials, and the selection method is: High-frequency optimization: compare the signal amplitude change rate of 1mm deep surface defects at different frequencies, and select the frequency with the highest change rate; Low-frequency optimization: compare the signal amplitude change rate of 1mm deep defects at different frequencies, and select the frequency with the highest change rate; Collection parameters: set the sampling frequency of the collection module to not less than 1MHz, select the excitation signal synchronous trigger, and ensure the phase consistency of signal collection; Step 3, real-time monitoring and signal acquisition: start the system for real-time monitoring, the excitation module applies a set of sinusoidal excitation signal to the excitation coil (4) of the array probe, and at the same time, the induced voltage signal is generated in the detection coil (5), and the acquisition module synchronously acquires the real-time signal V of each detection coil (5) t ; Step 4, reference signal acquisition and storage: place the array probe in the defect-free, uncoated, undeposited, and displacement-free reference area of the measured pipeline, and acquire the induced voltage signal of each detection coil (5) at this time as the respective reference signal V ref ; Step 5: Differential signal extraction: Perform the same filtering and denoising process on the acquired real-time signal Vt as on the reference signal, and then extract the processed real-time signal Vt. t With the stored reference signal V ref Subtracting them, we obtain the real-time differential signal ΔV (ΔV = V). t -V ref ); Step 6, calibration curve establishment: before formal measurement, the system needs to establish a measurement calibration curve on a standard test block: Defect depth calibration: Collect the differential signal ΔV of the detection coil (5) on the calibration block with a series of artificial defects of known depth, i.e. 0.5, 1.0, 2.0, 3.0 mm, and establish the database and fitting curve of "defect depth-differential signal ΔV"; Lift-off distance calibration: Collect the differential signal ΔV under different lift-off amounts, 0.1 mm to 3 mm, by precisely changing the distance between the probe and the surface of the block, i.e. lift-off, and establish the corresponding relationship curve of "lift-off distance-differential signal ΔV"; Vertical settlement / horizontal displacement calibration: Simulate the vertical settlement or horizontal displacement of the pipeline relative to the fixed pile (6) on the experimental device, record the corresponding relationship between the displacement amount and the differential signal, and establish the curve of "vertical settlement / horizontal displacement amount-differential signal ΔV"; Step 7, parameter analysis and calculation: According to the characteristics of the differential signal, combined with the pre-stored calibration curve, multi-parameter calculation is carried out: Internal defect identification and quantification: Analyze the differential signal under low-frequency excitation: extract the differential signal ΔV, query the "defect depth-differential signal amplitude ΔV" calibration curve, and calculate the equivalent depth of the defect; Non-conductive coating thickness measurement: Analyze the differential signal ΔV under high-frequency excitation: since the non-conductive coating does not affect the eddy current field, its thickness change is equivalent to lift-off change, according to the real-time differential signal ΔV, query the "lift-off distance-differential signal ΔV" calibration curve, and convert the thickness value of the coating; Settlement and displacement calculation: In the settlement / displacement monitoring mode, analyze the degree of signal amplitude attenuation, and according to the "vertical settlement / horizontal displacement amount-differential signal ΔV" calibration curve, calculate the actual settlement height or horizontal displacement distance of the pipeline from the signal amplitude drop; Step 8, result display: Use the host computer software to display the calculated defect depth, coating thickness, displacement amount and other parameters in the form of a data list in real time; Step 9, key area re-measurement: If abnormal signals are found in a certain area during monitoring, the software control can be used to perform intensive collection or continuous monitoring of the specific detection coil (5) corresponding to that area at a higher sampling frequency.

10. A method of detection for a flexible array eddy current multi-parameter detection system for natural gas pipelines according to claim 9, characterized in that: The step S8 displays the pipeline profile in the form of a two-dimensional or three-dimensional diagram, and superimposes the measurement results on the diagram in different colors or marks.

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