Overhead ground wire corrosion detection method and system based on pulsed eddy current

Abstract

The invention discloses a pulsed eddy current-based overhead ground wire corrosion detection method and system. The method comprises the following steps: acquiring an eddy current detection signal output by an annular pulsed eddy current sensor mounted on an overhead ground wire; according to the eddy current detection signal, obtaining a time domain characteristic value for representing the corrosion degree of the ground wire; the time domain characteristic value comprises a time domain characteristic value delta Smax of the magnetic conductivity variable quantity or / and a time domain characteristic value T delta S of the conductivity variable quantity; and comparing the time domain characteristic value delta Smax of the magnetic conductivity variable quantity or / and the time domain characteristic value T delta S of the conductivity variable quantity with a corresponding preset standard threshold value, and judging the corrosion degree of the overhead ground wire according to a comparison result. The method has the advantages of high detection efficiency, accurate detection and the like.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of overhead ground wire detection, and in particular to an overhead ground wire corrosion detection method and system based on pulse eddy current. Background Art

[0002] In order to protect high-voltage transmission lines from damage by lightning strikes, it is necessary to erect dedicated overhead ground wires to ensure the stable and safe operation of power transmission and transformation equipment. Common overhead ground wires (such as galvanized steel stranded ground wires) will corrode under stress, which is manifested in the destruction of the surface of the galvanized layer and the increase of corrosion current density. Under the tensile stress borne by the ground wire, the number of cracks on the surface of the galvanized layer increases, and the corrosive medium is more likely to enter the coating, resulting in a faster dissolution rate of zinc. In addition, in a humid, high-moisture and poorly ventilated environment, the salt and other chemicals in the rainwater will destroy the zinc oxide protective film on the surface of the galvanized layer, exposing the iron matrix, which is then corroded by air, water and other chemicals to form white rust spots. When the overhead ground wire corrodes, the overall tensile strength will be greatly reduced, and the risk of line breakage will easily occur.

[0003] At present, the main research at home and abroad focuses more on the corrosion status of different overhead ground wires under various corrosion environments, and there are not many studies on the corrosion degree detection methods of overhead ground wires. There are also some technologies for detecting the corrosion of overhead ground wires, such as the standard atlas method based on morphological changes, which analyzes the corrosion status by analyzing the surface morphological changes of the replaced ground wires; and the overhead ground wire corrosion morphology image analysis method based on machine vision, which determines the degree of corrosion on the outer surface of the overhead ground wire through visual recognition. However, the above detection methods are greatly affected by external environmental factors and the detection accuracy is not high. Therefore, there is a lack of a method that can evaluate the overall corrosion status of overhead ground wires in high-altitude environments. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention provides an overhead ground wire corrosion detection method and system based on pulse eddy current with high detection accuracy and high detection efficiency.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for detecting corrosion of an overhead ground wire based on pulsed eddy current comprises the following steps:

[0007] Acquire an eddy current detection signal output by an annular pulse eddy current sensor installed on an overhead ground wire;

[0008] According to the eddy current detection signal, a time domain characteristic value for characterizing the degree of ground wire corrosion is obtained; the time domain characteristic value includes the time domain characteristic value ΔS of the magnetic permeability change. max Or / and the time domain characteristic value T of the conductivity change ΔS ;

[0009] The time domain characteristic value ΔS of the permeability change max Or / and the time domain characteristic value T of the conductivity change ΔS The value is compared with the corresponding preset standard threshold, and the degree of corrosion of the overhead ground wire is determined based on the comparison result.

[0010] Preferably, the time domain characteristic value ΔS max The calculation process is:

[0011] In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S C Represents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested; ΔS represents the normalized value of the difference in corrosion degree between the two, as shown in the following formula:

[0012]

[0013] The maximum value of ΔS is taken as ΔS max .

[0014] Preferably, the time domain characteristic value ΔS of the magnetic permeability change max The specific process of comparing with the corresponding preset standard threshold and judging the degree of corrosion of the overhead ground wire according to the comparison result is as follows:

[0015] 0≤ΔS max When ≤S1, it is considered that there is no corrosion;

[0016] S1<ΔS max When ≤S2, it is considered that slight corrosion has occurred;

[0017] S2<ΔS max When ≤S3, moderate corrosion is considered to have occurred;

[0018] S3<ΔS max When ≤1, severe corrosion is considered to have occurred;

[0019] S1, S2, and S3 are obtained using simulation analysis based on the definitions of no corrosion, slight corrosion, moderate corrosion, and severe corrosion.

[0020] Preferably, the time domain eigenvalue T ΔS The calculation method is:

[0021] In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S CRepresents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested;

[0022] The difference between the normalized echo signals of the ground wire to be tested and the standard ground wire is considered to reflect the conductivity change of the corroded ground wire, that is, the time from the starting point to the peak value is recorded as T ΔS , used to represent the value of the conductivity of the ground wire to be measured;

[0023] T ΔS For S / S max -S C / S Cmax The time between the onset point and the peak value in the relationship diagram.

[0024] Preferably, the time domain characteristic value T of the conductivity change is ΔS The process of comparing with the corresponding preset standard threshold and judging the degree of corrosion of the overhead ground wire according to the comparison result is as follows:

[0025] 0≤T ΔS When ≤T1, it is considered that there is no corrosion;

[0026] T1 <T ΔS When ≤T2, it is considered that slight corrosion has occurred;

[0027] T2 <T ΔS When ≤T3, moderate corrosion is considered to have occurred;

[0028] T3 <T ΔS When ≤1, severe corrosion is considered to have occurred;

[0029] T1, T2, and T3 are obtained using simulation analysis based on the definitions of no corrosion, slight corrosion, moderate corrosion, and severe corrosion.

[0030] The invention also discloses an overhead ground wire corrosion detection system based on pulse eddy current, comprising a pulse eddy current sensor, a pulse transceiver, a power amplifier and a computer; the computer, the pulse transceiver, the power amplifier and the pulse eddy current sensor are connected in sequence.

[0031] Preferably, the pulse eddy current sensor is clamped on the overhead ground wire by a clamping claw.

[0032] The present invention further discloses a computer program product, comprising a computer program, wherein the computer program executes the steps of the method described above when executed by a processor.

[0033] The present invention also discloses a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described above are executed.

[0034] The present invention further discloses a computer device, comprising a memory and a processor connected to each other, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the method described above are executed.

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] The present invention achieves high-precision characterization of the corrosion degree of the overhead ground wire by using a pulse eddy current sensor that can collect high-precision signals, and can perform real-time detection of the corrosion degree of the overhead ground wire. The data collection is continuous, there is little human interference, and the detection data is reliable and accurate. In addition, the pulse eddy current sensor is easy to install and can avoid the influence of environmental factors. By extracting time domain eigenvalues, the corrosion degree can be quickly identified, complex data processing can be avoided, and the corrosion detection efficiency is improved. Changes in magnetic permeability and electrical conductivity can reflect tiny corrosion changes, making the method extremely sensitive to early corrosion or subtle defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural diagram of the pulse eddy current sensor in an embodiment of the present invention.

[0038] Figure 2 It is a schematic diagram of the structure of the detection system of the present invention in an embodiment.

[0039] Figure 3 It is a diagram representing the degree of change of the magnetic permeability of the overhead ground wire in the present invention.

[0040] Figure 4 It is a diagram representing the degree of change of the electrical conductivity of the overhead ground wire in the present invention.

[0041] Figure 5 The flowchart of the corrosion detection method in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0043] like Figure 5 As shown, the overhead ground wire corrosion detection method based on pulse eddy current in an embodiment of the present invention comprises the following steps:

[0044] Acquire an eddy current detection signal output by an annular pulse eddy current sensor installed on an overhead ground wire;

[0045] According to the eddy current detection signal, the time domain characteristic value used to characterize the degree of ground wire corrosion is obtained; the time domain characteristic value includes the time domain characteristic value ΔS of the magnetic permeability change max Or / and the time domain characteristic value T of the conductivity change ΔS ;

[0046] The time domain characteristic value ΔS of the permeability change max Or / and the time domain characteristic value T of the conductivity change ΔS The value is compared with the corresponding preset standard threshold, and the degree of corrosion of the overhead ground wire is determined based on the comparison result.

[0047] The present invention achieves high-precision characterization of the corrosion degree of the overhead ground wire by using a pulse eddy current sensor that can collect high-precision signals, and can perform real-time detection of the corrosion degree of the overhead ground wire. The data collection is continuous, there is little human interference, and the detection data is reliable and accurate. In addition, the pulse eddy current sensor is easy to install and can avoid the influence of environmental factors. By extracting time domain eigenvalues, the corrosion degree can be quickly identified, complex data processing can be avoided, and the corrosion detection efficiency is improved. Changes in magnetic permeability and electrical conductivity can reflect tiny corrosion changes, making the method extremely sensitive to early corrosion or subtle defects.

[0048] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0049] like Figure 1 As shown in the figure, the overhead ground wire corrosion detection method requires the use of a pulsed eddy current probe (pulsed eddy current sensor) clamped on the ground wire. The ground wire used is a galvanized steel stranded wire, model GJ-120, with an outer diameter of 14.5mm. The outer diameter of the pulsed eddy current sensor coil is 12mm, and the outer diameter of the receiving coil is 11mm. The side of the sensor is equipped with an encoder firmly bonded to the sensor to control the probe detection area; it is connected to the detection control system using a signal bus (data line). The sensor is in direct contact with the overhead ground wire, such as Figure 1 The spring clip (claw) shown provides a certain clamping force for the overhead ground wire to prevent it from falling off.

[0050] like Figure 2 As shown in the figure, the instrument and equipment used to realize the overhead ground wire corrosion detection mainly includes a pulse transceiver, a pulse eddy current sensor, a power amplifier, an acquisition card and a computer with signal processing function. Among them, the pulse transceiver uses a DPR-300 high-voltage pulse generator / receiver, which has extremely low noise receiving response and high-performance pulse emission control function. The instrument has gain adjustment, damping setting, high / low pass filtering and other functions. The NI PCI-5114 acquisition card is used to collect the electrical signal sent back by the pulse transceiver and realize analog-to-digital conversion. The sampling frequency of the input current is set to 10MHz.

[0051] like Figure 5 As shown in the figure, the overhead ground wire corrosion detection method based on pulse eddy current sensor has the following main steps:

[0052] S1. Install an annular pulse eddy current sensor on the overhead ground wire;

[0053] S2, control the pulse transceiver to excite the modulated Gaussian pulse, set the excitation source excitation frequency to 10kHz, the excitation voltage to 5V, convert the electric pulse into an electromagnetic field through the excitation coil, the receiving coil receives the differential response of the electromagnetic field from the ground wire and the excitation coil, and converts it into a voltage and sends it to the amplifier;

[0054] S3, controlling the eddy current sensor to perform detection at the position to be tested;

[0055] S4. Pre-calibrate and test the non-corroded galvanized steel strands of the same specification and batch, and obtain the signal data received by the pulse eddy current sensor under the same equipment parameters;

[0056] S5. Calculate the time domain characteristic value ΔS of the change in magnetic permeability and conductivity for the overhead ground wire before and after corrosion max With T ΔS ;

[0057] The time domain characteristic value ΔS used to represent the change in magnetic permeability is max The calculation method is:

[0058] In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S C Represents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested; ΔS represents the normalized value of the difference in corrosion degree between the two, as shown in the following formula:

[0059]

[0060] During the loop measurement of the conductor, the value of the magnetic permeability will change greatly, affecting the amplitude of the response signal. Therefore, ΔS max Represents the normalized change in magnetic permeability.

[0061] The time domain eigenvalue T used to represent the change in conductivity ΔS The calculation method is:

[0062] In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S C Represents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested. The difference between the normalized echo signal of the ground wire to be tested and the standard ground wire can be considered to reflect the change in the conductivity of the corroded ground wire, that is, the time from the starting point to the peak value is recorded as T ΔS, used to represent the value of the conductivity of the ground wire to be measured. T ΔS For S / S max -S C / S Cmax In the relationship diagram, the time between the onset point and the peak value. In actual measurement, it is necessary to perform differential analysis on the obtained signal data, and the time difference between the maximum and minimum values ​​is taken as this value.

[0063] Reference Figure 3 and Figure 4 , and obtain the time domain characteristic value ΔS of the galvanized steel strand to be tested max With T ΔS They are 0.35S and 0.09T0 respectively, both of which are normalized dimensionless values ​​and are in the interval [0,1].

[0064] S6. Determine the degree of corrosion:

[0065] The actual measured ΔS max With T ΔS Represents the degree of change in the magnetic permeability and electrical conductivity of the overhead ground wire, that is, the degree of wire corrosion. The specific determination method is as follows:

[0066] When using magnetic permeability for judgment:

[0067] 0≤ΔS max When ≤S1, it is considered that there is no corrosion;

[0068] S1<ΔS max When ≤S2, it is considered that slight corrosion has occurred;

[0069] S2<ΔS max When ≤S3, moderate corrosion is considered to have occurred;

[0070] S3<ΔS max When ≤1, severe corrosion is considered to have occurred;

[0071] When using conductivity for judgment:

[0072] 0≤T ΔS When ≤T1, it is considered that there is no corrosion;

[0073] T1 <T ΔS When ≤T2, it is considered that slight corrosion has occurred;

[0074] T2 <T ΔS When ≤T3, moderate corrosion is considered to have occurred;

[0075] T3 <T Δs When ≤1, severe corrosion is considered to have occurred;

[0076] S1, S2, S3 as well as T1, T2, T3 are obtained using the electromagnetic analysis module of the simulation analysis software based on the definitions of no corrosion, slight corrosion, moderate corrosion and severe corrosion.

[0077] The changes in magnetic permeability and electrical conductivity of galvanized steel stranded wire with an outer diameter of 14.5mm and a zinc coating of 0.1mm under different degrees of corrosion, as well as the changes in eddy current response under pulse eddy current excitation caused by the above, are calculated. The results show that S1=0.26, S2=0.49, S3=0.71 and T1=0.06, T2=0.15, T3=0.29.

[0078] The galvanized steel strand was judged to be slightly corroded by the magnetic permeability and slightly corroded by the electrical conductivity. Therefore, it is considered that the galvanized steel strand was slightly corroded.

[0079] Compared with traditional single-frequency eddy current testing, the pulsed eddy current testing of the present invention has many advantages, including greater detection depth, richer data information, stronger anti-interference ability, and the ability to intelligently identify structural parts within the coating layer; at the same time, pulses can be easily generated and controlled, and compared with multi-frequency eddy current methods, the cost of pulsed eddy current instruments is also lower; in addition, the changes in magnetic permeability and electrical conductivity caused by corrosion can be combined to simultaneously detect the degree of corrosion of overhead ground wires, and the reliability of the detection results can be enhanced by mutual verification.

[0080] An embodiment of the present invention further provides a computer program product, including a computer program, which executes the steps of the above method when executed by a processor. An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program, which executes the steps of the above method when executed by a processor. An embodiment of the present invention further provides a computer device, including a memory and a processor connected to each other, the memory storing a computer program, which executes the steps of the above method when executed by the processor.

[0081] The present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned method embodiment when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable storage media include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. The memory is used to store computer programs and / or modules, and the processor implements various functions by running or executing computer programs and / or modules stored in the memory, and calling data stored in the memory. The memory may include high-speed random access memory and may also include non-volatile memory, such as a hard disk, an internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0082] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for detecting corrosion of overhead ground wire based on pulse eddy current, characterized in that: Includes steps: Acquire an eddy current detection signal output by an annular pulse eddy current sensor installed on an overhead ground wire; According to the eddy current detection signal, a time domain characteristic value for characterizing the degree of ground wire corrosion is obtained; The time domain characteristic value includes the time domain characteristic value ΔS of the magnetic permeability change max Or / and the time domain characteristic value T of the conductivity change ΔS ; The time domain characteristic value ΔS of the permeability change max Or / and the time domain characteristic value T of the conductivity change ΔS The value is compared with the corresponding preset standard threshold, and the degree of corrosion of the overhead ground wire is determined based on the comparison result.

2. The method for detecting corrosion of overhead ground wire based on pulse eddy current according to claim 1, characterized in that: Time domain eigenvalue ΔS max The calculation process is: In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S C Represents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested; ΔS represents the normalized value of the difference in corrosion degree between the two, as shown in the following formula: The maximum value of ΔS is taken as ΔS max .

3. The method for detecting corrosion of overhead ground wire based on pulse eddy current according to claim 2, characterized in that: The time domain characteristic value ΔS of the permeability change max The specific process of comparing with the corresponding preset standard threshold and judging the degree of corrosion of the overhead ground wire according to the comparison result is as follows: 0≤ΔS max When ≤S1, it is considered that there is no corrosion; S1<ΔS max When ≤S2, it is considered that slight corrosion has occurred; S2<ΔS max When ≤S3, moderate corrosion is considered to have occurred; S3<ΔS max When ≤1, severe corrosion is considered to have occurred; S1, S2, and S3 are obtained using simulation analysis based on the definitions of no corrosion, slight corrosion, moderate corrosion, and severe corrosion.

4. The method for detecting corrosion of overhead ground wires based on pulsed eddy current according to claim 1, 2 or 3, characterized in that: Time domain eigenvalue T ΔS The calculation method is: In the same excitation pulse interval T0, S represents the echo signal of the uncorroded ground wire, S max Represents the maximum value of the echo signal of the uncorroded ground wire; S C Represents the echo signal of the corroded ground wire to be tested, S Cmax Indicates the maximum value of the echo signal of the corroded ground wire to be tested; The difference between the normalized echo signals of the ground wire to be tested and the standard ground wire is considered to reflect the conductivity change of the corroded ground wire, that is, the time from the starting point to the peak value is recorded as T ΔS , used to represent the value of the conductivity of the ground wire to be measured; T ΔS For S / S max -S C / S Cmax The time between the onset point and the peak value in the relationship diagram.

5. The method for detecting corrosion of overhead ground wires based on pulsed eddy current according to claim 4, characterized in that: The time domain characteristic value T of the conductivity change ΔS The process of comparing with the corresponding preset standard threshold and judging the degree of corrosion of the overhead ground wire according to the comparison result is as follows: 0≤T ΔS When ≤T1, it is considered that there is no corrosion; T1 <T ΔS When ≤T2, it is considered that slight corrosion has occurred; T2 <T ΔS When ≤T3, moderate corrosion is considered to have occurred; T3 <T ΔS When ≤1, severe corrosion is considered to have occurred; T1, T2, and T3 are obtained using simulation analysis based on the definitions of no corrosion, slight corrosion, moderate corrosion, and severe corrosion.

6. An overhead ground wire corrosion detection system based on pulse eddy current, characterized in that: The invention comprises a pulse eddy current sensor, a pulse transceiver, a power amplifier and a computer; the computer, the pulse transceiver, the power amplifier and the pulse eddy current sensor are connected in sequence.

7. The overhead ground wire corrosion detection system based on pulse eddy current according to claim 6 is characterized in that: The pulse eddy current sensor is clamped on the overhead ground wire by means of clamping claws.

8. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are performed.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the computer program performs the steps of the method according to any one of claims 1 to 5.

10. A computer device comprising a memory and a processor connected to each other, wherein a computer program is stored in the memory, characterized in that: When the computer program is executed by a processor, the computer program performs the steps of the method according to any one of claims 1 to 5.

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