CN117783054A - Cable moisture defect detection method, control device and system - Google Patents

Abstract

The invention provides a detection method, a control device and a system for a cable wetting defect, and belongs to the technical field of cable detection. The method comprises the following steps: acquiring a plurality of echo signals obtained by detecting a target cable through terahertz signals; each echo signal corresponds to one detection coordinate of the target cable, the target cable has different axial rotation angles and axial endpoint distances under each detection coordinate, the adjacent two detection coordinates differ by a preset angle step or a preset distance step, and the target cable has double insulating layers; combining the amplitude values of the echo signals into a two-dimensional data list by taking the axial rotation angle as a first coordinate and the axial endpoint distance as a second coordinate; and judging whether the target cable has a damp defect or not based on the uniformity degree of amplitude distribution in the two-dimensional data list. The invention can avoid inaccurate detection results caused by fluctuation of echo signals under a single detection coordinate.

Description

Detection method, control device and system for cable moisture defects

Technical field

The present invention relates to the technical field of cable detection, and in particular to a method, control device and system for detecting moisture defects in cables.

Background technique

Cross-linked polyethylene cable plays an extremely important role in the power supply grid. Power cables work in complex environments for a long time, and the cable performance declines with the aging of the lines, posing a threat to the safe operation of the power grid. Cable joints are weak links in cable lines and are susceptible to failure due to factors such as complex operating conditions, changing external environments, and sudden external force damage. Among them, moisture defects occur more frequently.

Terahertz signals can penetrate non-metallic materials and form reflected echoes after reaching different interfaces. The amplitude of the echoes can be used to determine the status of the interface. Currently, the echo signals of the cable under inspection are usually compared with the echo signals of the standard test piece. Compare to determine whether there are moisture defects inside the cable being inspected. However, the moisture inside the cable is complicated, and the shape of the cable during detection is not completely regular. The resulting signal fluctuations will affect the determination of the interface, resulting in lower accuracy of the detection results.

Contents of the invention

Embodiments of the present invention provide a method, a control device and a system for detecting moisture defects in cables to solve the problem of low accuracy in detecting moisture defects in cables.

In a first aspect, embodiments of the present invention provide a method for detecting moisture defects in cables, including:

Acquire multiple echo signals obtained by detecting the target cable through terahertz signals; among them, each echo signal corresponds to a detection coordinate of the target cable, and the target cable has different axial rotation angles and axes at each detection coordinate. The distance to the endpoint, the range of the axial rotation angle is [0°, 360°], the range of the axial endpoint distance is [0, L], L represents the length of the target cable, and the difference between two adjacent detection coordinates is preset Angle steps or preset distance steps, the target cable has double insulation;

With the axial rotation angle as the first coordinate and the axial end point distance as the second coordinate, the amplitudes of the respective echo signals are combined into a two-dimensional data list;

Based on the uniformity of the amplitude distribution in the two-dimensional data list, it is judged whether the target cable has a moisture defect.

In one possible implementation, it is judged whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list, including:

For each echo signal, determine the gray value corresponding to the echo signal based on the amplitude of the echo signal;

Based on the coordinates and corresponding gray value of each echo signal, the echo image of the target cable is generated;

Based on the uniformity of the color distribution of the echo image, it is judged whether there is a moisture defect in the target cable.

In one possible implementation, it is determined whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, including:

Based on the gray value distribution in the echo image, the echo image is divided into a plurality of regions;

If there is an abnormal color area, it is determined that the target cable has a moisture defect; among them, when the gray value corresponding to each echo signal increases with the increase in amplitude, the abnormal color area is the area where the average gray value is greater than the gray threshold. , when the gray value corresponding to each echo signal decreases as the amplitude increases, the color abnormal area is the area where the average gray value is less than the gray threshold, and the gray threshold is determined based on each gray value in the echo image.

In a possible implementation, after determining whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, the method also includes:

Determine the area of the wet area in the target cable based on the area of the color abnormal area.

In one possible implementation, it is determined whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list, including:

Cluster each amplitude based on its coordinates and amplitude to obtain multiple clusters;

Determine the uniformity of the amplitude distribution in the two-dimensional data list based on the average amplitude of each cluster;

If there is a cluster whose average amplitude is greater than the preset amplitude threshold, it is determined that the target cable has a moisture defect.

In a possible implementation, before combining the amplitudes of each echo signal into a two-dimensional data list with the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, it also includes:

Preprocess multiple echo signals to obtain multiple preprocessed echo signals;

Correspondingly, with the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each echo signal are combined into a two-dimensional data list, including:

Taking the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each preprocessed echo signal are combined into a two-dimensional data list.

In a possible implementation, multiple echo signals are preprocessed to obtain multiple preprocessed echo signals, including:

Effective signal interception is performed on multiple echo signals based on a preset time period to obtain multiple preprocessed echo signals.

In a possible implementation, multiple echo signals are preprocessed to obtain multiple preprocessed echo signals, including:

Phase alignment is performed on multiple echo signals to obtain multiple preprocessed echo signals.

In a second aspect, an embodiment of the present invention provides a control device for executing the steps of the method described in the above first aspect or any possible implementation of the first aspect.

In a third aspect, embodiments of the present invention provide a cable moisture defect detection system, including a rotating platform, a lifting platform, a signal transmitting device, a signal collecting device and a control device as described in the second aspect; the first end of the target cable Connected to the rotating table, the second end of the target cable is connected to the lifting table;

The signal transmitting device is used to transmit a terahertz signal to the target cable perpendicular to the axis of the target cable;

The rotating platform is used to drive the first end and the second end of the target cable to rotate around the axial direction to change the axial rotation angle of the target cable;

The lifting platform is used to drive the second end of the target cable to move axially to change the axial end point distance of the target cable;

The signal acquisition device is used to collect the echo signals generated by the target cable at various detection coordinates.

Embodiments of the present invention provide a method, control device and system for detecting moisture defects in cables. The state of the insulation layer interface of the target cable is determined through the echo signal of the terahertz signal. A list of echo signals is constructed by detecting coordinates, and the target cable's By horizontally comparing the echo signals at different detection coordinates, the moisture inside the cable can be judged without comparing it with the echo signal generated by the standard test piece, which can avoid the fluctuation of the echo signal at a single detection coordinate causing detection The results are inaccurate.

Description of the drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings in the following description are only illustrative of the present invention. For some embodiments, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is an implementation flow chart of a method for detecting moisture defects in cables provided by an embodiment of the present invention;

Figure 2 is a schematic structural diagram of a cable provided by an embodiment of the present invention;

FIG3 is a schematic diagram of a cable structure having a moisture defect provided by an embodiment of the present invention;

Figure 4 is an application scenario diagram of the method for detecting moisture defects in cables provided by the embodiment of the present invention;

Figure 5 is an echo image of a cable with moisture defects provided by an embodiment of the present invention;

Figure 6 is an echo image of a cable with moisture defects provided by another embodiment of the present invention;

Figure 7 is a time domain image of the echo signal provided by the embodiment of the present invention;

Figure 8 is a comparison diagram of the amplitude of echo signals of cables with moisture defects and cables without moisture defects provided by the embodiment of the present invention;

Figure 9 is a schematic structural diagram of a cable moisture defect detection device provided by an embodiment of the present invention.

Detailed ways

In the following description, specific details such as specific system structures and technologies are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the present invention in unnecessary detail.

In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

Figure 1 is an implementation flow chart of a method for detecting moisture defects in cables provided by an embodiment of the present invention. The details are as follows:

Step 101, obtain multiple echo signals obtained by detecting the target cable through terahertz signals; wherein each echo signal corresponds to a detection coordinate of the target cable, and the target cable has different axial rotations at each detection coordinate. Angle and axial endpoint distance, the range of axial rotation angle is [0°, 360°], the range of axial endpoint distance is [0, L], L represents the length of the target cable, between two adjacent detection coordinates Offset by preset angle steps or preset distance steps, the target cable has double insulation.

In this embodiment, terahertz signals can penetrate non-metallic materials and form reflected echoes after reaching different interfaces. The status of the interface can be determined by the amplitude of the echo signals.

Referring to Figures 2 and 3, the cable includes a metal core and two layers of insulation. The two layers of insulation are a sealed insulation sheath and a cross-linked polyethylene insulation layer. In the non-moistened area, the sealed insulating sheath is tightly attached to the cross-linked polyethylene layer, and the sealed insulating sheath and the cross-linked polyethylene layer are tightly attached without any air gaps. A water film exists between the sealed insulating sheathing and the cross-linked polyethylene layer in the damp area. It can be seen that cables with moisture defects have an extra layer of water film between the two insulation layers compared to cables that are not damp. In view of this characteristic, the terahertz signal can be used to detect the cable, and based on the echo signal, it can be determined whether there is a water film between the two insulation layers of the cable, and then whether there is a moisture defect in the cable. During the test, a wet paper film containing water can be placed between the two insulation layers to form a cable standard specimen with a damp area, and the reflection characteristics of the cable with moisture defects to the terahertz signal can be tested.

During detection, the terahertz signal needs to be aligned and radially injected perpendicular to the axis of the cable into the insulation layer interface of the cable. However, the shape of the cable during detection is not completely regular. Different shapes of cables cause different fluctuations in the echo signal. , causing the detected echo signal to be interfered by uncertainty, affecting the judgment at the interface. In this regard, the shape of the cable can be adjusted during detection, and the echo signals at all detection coordinates are collected for lateral comparison, and the influence of the cable shape and detection angle on the echo signals can be eliminated as much as possible.

Specifically, as shown in Figure 4, a cylindrical coordinate scanning device composed of a one-dimensional lifting table and a rotating table can be used to adjust the detection coordinates during detection. The first end of the target cable is connected to the rotating table, and the second end is connected to the lifting table. The Hertz signal is aligned with the center of the cable and transmitted to the surface of the insulation layer of the target cable, and the incident direction is perpendicular to the axis of the target cable. The rotary table rotates around the axis of the cable according to the preset angle step. The rotation angle φ ranges from 0° to 360°. Both ends of the target cable rotate with the rotary table; the lifting table moves according to the preset distance step. The second end of the cable is driven to move, and the distance between the two ends of the cable is changed to change the shape of the cable. The moving direction is the axial direction of the target cable, and the range of the moving distance z is set according to the length of the cable. The time domain waveform of the echo signal is collected at each detection coordinate (φ, z) for lateral comparison.

Step 102: Using the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, combine the amplitudes of each echo signal into a two-dimensional data list.

In this embodiment, the target cable is regarded as a cylinder, and the insulation layer of the target cable can be expanded into a rectangle. The side where the bottom surface of the rectangle is is the width of the rectangle, and the other side is the length of the rectangle. Each echo The axial rotation angle where the signal is located corresponds to a width coordinate of the rectangle, and the axial endpoint distance corresponds to a length coordinate of the rectangle. It can be seen that the axial rotation angle is the first coordinate, and the axial endpoint distance is the second coordinate. Each return The two-dimensional data list obtained by combining the amplitudes of the wave signals is a two-dimensional data list of the amplitudes of the echo signals corresponding to each point on the insulation layer of the target cable.

Step 103: Determine whether the target cable has a moisture defect based on the uniformity of the amplitude distribution in the two-dimensional data list.

In this embodiment, the uniformity of the amplitude distribution in the two-dimensional data list can reflect the distribution of the reflection characteristics of the terahertz signal at each point on the insulation layer interface of the target cable. If there are dampened areas and non-moistened areas in the insulating layer interface, that is, there is a water film in some areas, then the reflection characteristics of the terahertz signal at each point on the insulating layer interface are different, which will lead to uneven amplitude distribution in the two-dimensional data list. , so whether there is a moisture defect can be judged based on the uniformity of the amplitude distribution in the two-dimensional data list.

The embodiment of the present invention determines the status of the cable insulation layer interface through the echo signal of the terahertz signal, constructs a list of echo signals through detection coordinates, and compares the echo signals of the target cable under different detection coordinates laterally, without the need to compare with the standard By comparing the echo signals generated by the test piece, the moisture inside the cable can be judged, which can avoid the fluctuation of the echo signal under a single detection coordinate causing inaccurate detection results.

In a possible implementation, judging whether the target cable has a moisture defect based on the uniformity of the amplitude distribution in the two-dimensional data list includes:

For each echo signal, determine the gray value corresponding to the echo signal based on the amplitude of the echo signal;

Based on the coordinates and corresponding gray value of each echo signal, the echo image of the target cable is generated;

Whether the target cable has moisture defects is determined based on the uniformity of the color distribution of the echo image.

In this embodiment, the echo signal is a time domain signal, and the peak value of the amplitude of each echo signal can be extracted as the amplitude of the echo signal. The echo image is a grayscale image, and the grayscale value corresponding to each echo signal can be set to decrease as the amplitude increases, or the grayscale value corresponding to each echo signal can be set to increase as the amplitude increases. Referring to Figures 5 and 6, the change in the amplitude of the echo signal is represented by the change in color depth in the echo image. The area with similar color in the image is the area with similar amplitude of the echo signal, which more intuitively reflects the amplitude change of the echo signal at each position on the interface of the insulation layer of the target cable.

In one possible implementation, it is determined whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, including:

Based on the gray value distribution in the echo image, the echo image is divided into multiple areas;

If there is an abnormal color area, it is determined that the target cable has a moisture defect; when the grayscale value corresponding to each echo signal increases with the increase of the amplitude, the abnormal color area is an area where the average grayscale value is greater than the grayscale threshold; when the grayscale value corresponding to each echo signal decreases with the increase of the amplitude, the abnormal color area is an area where the average grayscale value is less than the grayscale threshold, and the grayscale threshold is determined based on the grayscale values in the echo image.

In this embodiment, the grayscale threshold may be an average value of grayscale values in the echo image, or may be a grayscale value that appears most frequently in the echo image, or may be determined based on a characteristic value of a specific cable target.

In this embodiment, it is possible to detect target cables that are unknown whether they are damp or not, without establishing an echo characteristic database of standard test pieces. If the color distribution of the echo image is uneven, it means there is a moisture defect, and if the color distribution of the echo image is uniform, it means there is no moisture defect.

In a possible implementation, after determining whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, the method also includes:

Determine the area of the wet area in the target cable based on the area of the color abnormal area.

In this embodiment, since the insulation layer of the target cable can be expanded into a rectangle, the axial rotation angle of each echo signal corresponds to a width coordinate of the rectangle, and the axial endpoint distance corresponds to a length coordinate of the rectangle, then The color of each point in the echo image can represent the signal reflection characteristics of the corresponding point on the rectangle. It can be seen that the shape of the color abnormal area in the echo image corresponds to the shape of the damp area on the rectangle. The ratio of the area of the color abnormality area to the area of the echo image can correspond to the ratio of the area of the damp area on the rectangle to the area of the rectangle, from which the area of the damp area of the target cable can be calculated.

In one possible implementation, it is judged whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list, including:

Cluster each amplitude based on its coordinates and amplitude to obtain multiple clusters;

Determine the uniformity of the amplitude distribution in the two-dimensional data list based on the average amplitude of each cluster;

If there is a cluster whose average amplitude is greater than the preset amplitude threshold, it is determined that the target cable has a moisture defect.

In this embodiment, clustering can classify data corresponding to echo signals with similar coordinates and amplitudes into a cluster. The average amplitude of the cluster is greater than the preset amplitude threshold, indicating that the cluster has The amplitudes of each point are high, indicating that the target cable has moisture defects. The preset amplitude threshold can be the average of all amplitudes in the two-dimensional data list, or the amplitude that occurs most frequently.

In a possible implementation, before combining the amplitudes of each echo signal into a two-dimensional data list with the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, it also includes:

Preprocess multiple echo signals to obtain multiple preprocessed echo signals;

Correspondingly, with the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each echo signal are combined into a two-dimensional data list, including:

With the axial rotation angle as the first coordinate and the axial end point distance as the second coordinate, the amplitudes of the pre-processed echo signals are combined into a two-dimensional data list.

In this embodiment, preprocessing the echo signal can remove invalid parts of the echo signal and improve the accuracy of the detection results.

In a possible implementation, preprocessing the multiple echo signals to obtain the multiple preprocessed echo signals includes:

Effective signal interception is performed on multiple echo signals based on a preset time period to obtain multiple preprocessed echo signals.

In this embodiment, the time domain images of the echo signal are shown in Figures 7 and 8. The thicker curve in Figure 8 is the echo signal of the cable without moisture defects, and the thinner curve is the echo signal of the cable with moisture defects. The effective signal can be intercepted from the echo signal according to the preset time period, and only the echo of the terahertz signal at the interface between the sealed insulating sheath and the cross-linked polyethylene layer is retained, reducing the interference of the echo signal in other time periods on the detection result.

In a possible implementation, multiple echo signals are preprocessed to obtain multiple preprocessed echo signals, including:

Phase alignment is performed on multiple echo signals to obtain multiple preprocessed echo signals.

In this embodiment, phase alignment can ensure that the phases of each preprocessed echo signal are consistent, making the intercepted effective signal more accurate.

It should be understood that the sequence number of each step in the above embodiment does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

The following is an embodiment of the device of the present invention. For details not described in detail, reference may be made to the corresponding method embodiment described above.

Figure 9 shows a schematic structural diagram of a device for detecting moisture defects in cables provided by an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown. The details are as follows:

As shown in Figure 9, the cable moisture defect detection device 9 includes:

The acquisition module 91 is used to acquire multiple echo signals obtained by detecting the target cable through terahertz signals; wherein each echo signal corresponds to a detection coordinate of the target cable, and the target cable has different detection coordinates at each detection coordinate. Axial rotation angle and axial end point distance, the range of axial rotation angle is [0°, 360°], the range of axial end point distance is [0, L], L represents the length of the target cable, two adjacent detection The difference between the coordinates is a preset angle step or a preset distance step, and the target cable has double insulation layers;

A combination module 92, for combining the amplitudes of the respective echo signals into a two-dimensional data list with the axial rotation angle as the first coordinate and the axial end point distance as the second coordinate;

The judgment module 93 is used to judge whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list.

In a possible implementation, the judgment module 93 is specifically used to:

For each echo signal, determine a grayscale value corresponding to the echo signal based on the amplitude of the echo signal;

Based on the coordinates and corresponding gray value of each echo signal, the echo image of the target cable is generated;

Based on the uniformity of the color distribution of the echo image, it is judged whether there is a moisture defect in the target cable.

In a possible implementation, the judgment module 93 is specifically used to:

Based on the gray value distribution in the echo image, the echo image is divided into a plurality of regions;

If there is an abnormal color area, it is determined that the target cable has a moisture defect; among them, when the gray value corresponding to each echo signal increases as the amplitude increases, the color abnormal area is the area where the average gray value is greater than the gray threshold. , when the gray value corresponding to each echo signal decreases as the amplitude increases, the color abnormal area is the area where the average gray value is less than the gray threshold, and the gray threshold is determined based on each gray value in the echo image.

In a possible implementation, the judgment module 93 is also used to:

After determining whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, the area of the moisture affected area in the target cable is determined based on the area of the abnormal color area.

In a possible implementation, the determination module 93 is specifically configured to:

Cluster each amplitude based on its coordinates and amplitude to obtain multiple clusters;

Determine the uniformity of the amplitude distribution in the two-dimensional data list based on the average amplitude of each cluster;

If there is a cluster whose average amplitude is greater than the preset amplitude threshold, it is determined that the target cable has a moisture defect.

In a possible implementation, the combination module 92 is specifically used to:

Before combining the amplitudes of each echo signal into a two-dimensional data list with the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, multiple echo signals are preprocessed to obtain multiple processes. Preprocessed echo signal;

Taking the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each preprocessed echo signal are combined into a two-dimensional data list.

In a possible implementation, the combination module 92 is specifically used to:

Effective signal interception is performed on multiple echo signals based on a preset time period to obtain multiple preprocessed echo signals.

In a possible implementation, the combination module 92 is specifically used to:

Phase alignment is performed on multiple echo signals to obtain multiple preprocessed echo signals.

The embodiment of the present invention determines the status of the cable insulation layer interface through the echo signal of the terahertz signal, constructs a list of echo signals through detection coordinates, and compares the echo signals of the target cable under different detection coordinates laterally, without the need to compare with the standard By comparing the echo signals generated by the test piece, the moisture condition inside the cable can be judged, which can avoid the fluctuation of the echo signal under a single detection coordinate causing inaccurate detection results.

An embodiment of the present invention also provides a control device for executing the steps of the method described in the above first aspect or any possible implementation of the first aspect.

Embodiments of the present invention also provide a cable moisture defect detection system, which includes a rotating platform, a lifting platform, a signal transmitting device, a signal collecting device and a control device as described in the second aspect above; the first end of the target cable is connected to the rotating platform Connect, the second end of the target cable is connected to the lifting platform;

The signal transmitting device is used to transmit a terahertz signal to the target cable perpendicular to the axis of the target cable;

The rotating stage is used to drive the first end and the second end of the target cable to rotate around the axis to change the axial rotation angle of the target cable;

The lifting platform is used to drive the second end of the target cable to move along the axial direction to change the axial end point distance of the target cable;

The signal acquisition device is used to collect the echo signals generated by the target cable at various detection coordinates.

In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

Those of ordinary skill in the art can appreciate that the templates, units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered to be beyond the scope of the present invention.

If the module/unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the processes in the methods of the above embodiments, and can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can be stored in a computer-readable storage medium. When the program is executed by the processor, the steps of the above embodiments of the method for detecting moisture defects in cables can be implemented. Wherein, the computer program includes computer program code, which may be in the form of source code, object code, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording media, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier wave signals, telecommunications signals, and software distribution media, etc.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still implement the above-mentioned implementations. The technical solutions described in the examples are modified, or some of the technical features are equivalently replaced; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention, and should be included in within the protection scope of the present invention.

Claims (10)

1. A method for detecting moisture defects in cables, which is characterized by including: Acquire multiple echo signals obtained by detecting the target cable through terahertz signals; wherein each echo signal corresponds to a detection coordinate of the target cable, and the target cable has different axial directions at each detection coordinate. Rotation angle and axial end point distance. The range of the axial rotation angle is [0°, 360°], and the range of the axial end point distance is [0, L]. L represents the length of the target cable. The difference between two adjacent detection coordinates is a preset angle step or a preset distance step, and the target cable has a double insulation layer; Using the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, combine the amplitudes of each echo signal into a two-dimensional data list; It is determined whether the target cable has a moisture defect based on the uniformity of the amplitude distribution in the two-dimensional data list. 2. The method for detecting moisture defects in cables according to claim 1, wherein determining whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list includes: For each echo signal, determine the gray value corresponding to the echo signal based on the amplitude of the echo signal; Generate an echo image of the target cable based on the coordinates and corresponding gray value of each echo signal; It is determined whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image. 3. The cable moisture defect detection method according to claim 2, characterized in that the step of judging whether the target cable has a moisture defect based on the uniformity of the color distribution of the echo image comprises: Based on the gray value distribution in the echo image, divide the echo image into multiple areas; If there is an abnormal color area, it is determined that the target cable has a moisture defect; wherein, when the grayscale value corresponding to each echo signal increases with the increase of the amplitude, the abnormal color area is an area where the average grayscale value is greater than the grayscale threshold, and when the grayscale value corresponding to each echo signal decreases with the increase of the amplitude, the abnormal color area is an area where the average grayscale value is less than the grayscale threshold, and the grayscale threshold is determined based on the grayscale values in the echo image. 4. The method for detecting moisture defects in cables according to claim 3, characterized in that after determining whether there is a moisture defect in the target cable based on the uniformity of the color distribution of the echo image, it further includes: The area of the damp area in the target cable is determined based on the area of the abnormal color area. 5. The method for detecting moisture defects in cables according to claim 1, wherein determining whether there is a moisture defect in the target cable based on the uniformity of the amplitude distribution in the two-dimensional data list includes: Clustering each amplitude based on the coordinates and amplitude of each amplitude to obtain multiple clusters; Determine the uniformity of the amplitude distribution in the two-dimensional data list based on the average amplitude of each cluster; If there is a cluster whose amplitude average value is greater than a preset amplitude threshold, it is determined that the target cable has a moisture defect. 6. The method for detecting moisture defects in cables according to claim 1, characterized in that, using the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitude of each echo signal is Before combining into a two-dimensional data list, it also includes: Preprocess the multiple echo signals to obtain multiple preprocessed echo signals; Correspondingly, using the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each echo signal are combined into a two-dimensional data list, including: Taking the axial rotation angle as the first coordinate and the axial endpoint distance as the second coordinate, the amplitudes of each preprocessed echo signal are combined into a two-dimensional data list. 7. The method for detecting moisture defects in cables according to claim 6, wherein the plurality of echo signals are preprocessed to obtain a plurality of preprocessed echo signals, including: Effective signal interception is performed on the multiple echo signals based on a preset time period to obtain multiple pre-processed echo signals. 8. The method for detecting moisture defects in cables according to claim 6, characterized in that, the plurality of echo signals are preprocessed to obtain a plurality of preprocessed echo signals, including: Phase alignment is performed on the multiple echo signals to obtain multiple preprocessed echo signals. 9. A control device, characterized in that it is used to execute the steps as claimed in claims 1 to 8. 10. A cable moisture defect detection system, characterized in that it comprises a rotating platform, a lifting platform, a signal transmitting device, a signal collecting device and the control device according to claim 9; the first end of the target cable is connected to the rotating platform, and the second end of the target cable is connected to the lifting platform; The signal transmitting device is configured to transmit a terahertz signal to the target cable perpendicular to the axis of the target cable; The rotary table is used to drive the first end and the second end of the target cable to rotate around the axis to change the axial rotation angle of the target cable; The lifting platform is used to drive the second end of the target cable to move along the axial direction to change the axial end point distance of the target cable; The signal acquisition device is used to collect echo signals generated by the target cable at various detection coordinates.