A method for on-line detection of the thickness of the insulation layer of a power cable

Abstract

The application discloses a kind of power cable insulation layer thickness on-line detection method, it is related to thickness detection technical field, including the following steps: by the power cable to be detected and ultrasonic probe acquisition real-time reflection time length;Real-time target time length is obtained by real-time reflection time length;First drawing straight line is obtained by real-time target time length;First target point, second target point and third target point are obtained by real-time target time length and first drawing straight line;First threshold straight line is obtained according to first target point and second target point;Second threshold straight line is obtained by first target point and third target point;Real-time point position time length is obtained by real-time target time length, first threshold straight line and second threshold straight line;Real-time point position thickness is obtained by real-time point position time length;Cable insulation layer thickness is detected by real-time point position thickness;The application is used to solve the problem that the accuracy of the thickness obtained is low due to the deviation and abnormal data of the collected data in the existing technology.

Description

Technical Field

[0001] This invention relates to the field of thickness detection technology, specifically to an online method for detecting the thickness of the insulation layer of power cables. Background Technology

[0002] The insulation layer of power cables is essential for ensuring the electrical insulation performance and long-term operational safety of the cables. Its thickness uniformity, minimum thickness, and eccentricity are key indicators for quality control in cable production, determining the reliability of power transmission and service life of the cables. Therefore, online detection of the insulation layer thickness of power cables is necessary.

[0003] The basic process of acoustic wave detection of insulation layer thickness utilizes the characteristic that ultrasonic waves travel at different speeds in different media. When ultrasonic waves propagate from one medium to another, they are reflected at the interface. Since the cable conductor and the insulation layer are different media, the external probe receives two returned ultrasonic echo signals, thereby obtaining the insulation layer thickness. However, it is difficult for the cable and the probe to be perfectly centered. The cable is eccentric relative to the probe, the incident angle of the acoustic waves shifts, and the echo propagation path becomes longer, leading to systematic thickness measurement errors and interference from abnormal data. For example, patent application CN120176587A discloses an online detection method for the insulation layer thickness of power cables. The data collected by this scheme will have offset and abnormal data, resulting in low accuracy in obtaining the thickness. In other words, existing technologies suffer from offset and abnormal data in the collected data, leading to low accuracy in obtaining the thickness. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in the prior art. It involves obtaining real-time reflection duration using an ultrasonic probe and a power cable under test; obtaining a real-time target duration using the real-time reflection duration; obtaining a first drawn straight line using the real-time target duration; obtaining a first target point, a second target point, and a third target point using the real-time target duration and the first drawn straight line; obtaining a first threshold straight line based on the first and second target points; obtaining a second threshold straight line using the first and third target points; obtaining a real-time point duration using the real-time target duration, the first threshold straight line, and the second threshold straight line; obtaining a real-time point thickness using the real-time point duration; and detecting the cable insulation layer thickness using the real-time point thickness, thereby solving problem 1.

[0005] To achieve the above objectives, this application provides an online method for detecting the thickness of the insulation layer of power cables, comprising the following steps: Step S100: Obtain the real-time reflection duration through the power cable to be tested and the ultrasonic probe; Step S200: Obtain the real-time target duration through the real-time reflection duration; obtain the first drawn straight line through the real-time target duration; obtain the first target point, the second target point, and the third target point through the real-time target duration and the first drawn straight line; obtain the first threshold straight line based on the first target point and the second target point; obtain the second threshold straight line through the first target point and the third target point; obtain the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line. Step S300: Obtain the real-time point thickness by measuring the real-time point duration; Step S400: The thickness of the cable insulation layer is detected by real-time point thickness measurement.

[0006] Furthermore, step S100 also includes the following sub-steps: Obtain the power cable to be inspected and mark it as the target cable; Define a reference bottom surface, and mark it as the first reference surface; Position the target cable above the first reference plane and make the target cable parallel to the first reference plane; Above the target cable and the first reference plane, obtain a plane parallel to the first reference plane and mark it as the second reference plane; On the second reference plane, obtain a straight line parallel to the target cable and mark it as the first cable straight line; On the second reference plane, obtain a straight line perpendicular to the first cable line and mark it as the first perpendicular straight line; The ultrasonic probe is always perpendicular to the first reference surface. Then, the ultrasonic probe is moved above the target cable along the first vertical line. The time from the generation of ultrasonic waves on the surface of the target cable to the first receipt of the reflected ultrasonic waves is marked as the real-time reflection time.

[0007] Furthermore, step S200 also includes the following sub-steps: At any position of the ultrasonic probe, acquire the first number of real-time reflection durations and mark them as the real-time target durations; A Cartesian coordinate system is established with the real-time target duration as the horizontal axis value, and it is marked as the first target coordinate system; Obtain the average duration of all real-time targets and mark it as the average real-time duration; Obtain the horizontal and vertical axes of the first target coordinate system, and label them as the first horizontal axis and the first vertical axis, respectively; The first line to be drawn is defined as: X=b; where X is the horizontal axis value of the first target coordinate system, and b is the average real-time duration. Draw the first line in the first target coordinate system.

[0008] Furthermore, step S200 also includes the following sub-steps: Obtain the difference between the real-time target duration and the average real-time duration, and mark it as the real-time target difference; If the real-time target difference is less than 0, the absolute value of the real-time target difference is marked as the first target difference; If the real-time target difference is equal to 0, mark the real-time target difference as the second target difference; If the real-time target difference is greater than 0, mark the real-time target difference as the third target difference.

[0009] Furthermore, step S200 also includes the following sub-steps: The lengths of the first target difference, the second target difference, and the third target difference on the first horizontal axis are marked as the first offset length; If the real-time target difference is less than 0, starting from any point on the first drawing line, draw a point in the negative direction of the first horizontal axis and in the perpendicular direction of the first drawing line, with a distance of the first drawing line equal to the first offset length, and mark it as the first target point; If the real-time target difference is equal to 0, any point will be drawn on the first drawing line and marked as the second target point; If the real-time target difference is greater than 0, starting from any point on the first drawing line, draw a point in the positive direction of the first horizontal axis and in the perpendicular direction of the first drawing line, with a distance of the first drawing line equal to the first offset length, and mark it as the third target point.

[0010] Furthermore, step S200 also includes the following sub-steps: Mark the first target point and the second target point as the first set of points, set a straight line parallel to the first vertical axis, and make the number of the first set of points on the left and right sides of the line equal, and mark this line as the second target line; Obtain the distance between the first drawn straight line and the second target straight line, and mark it as the first data distance; Set a ratio and mark it as the first set ratio; Obtain the product of the first data distance and the first set ratio, and mark it as the first threshold distance; To the left of the second target line, at a distance equal to the first threshold distance from the second target line, obtain a line parallel to the first vertical axis and mark it as the first threshold line.

[0011] Furthermore, step S200 also includes the following sub-steps: Mark both the first target point and the third target point as the second group of points. Set a straight line parallel to the first vertical axis, and make the number of the second group of points on the left and right sides of the line equal. Mark this line as the third target line. Obtain the distance between the first drawn line and the third target line, and mark it as the second data distance; Set a ratio and mark it as the second set ratio; Obtain the product of the second data distance and the second set ratio, and mark it as the second threshold distance; To the right of the third target line, at a distance equal to the second threshold distance from the third target line, obtain a line parallel to the first vertical axis and mark it as the second threshold line.

[0012] Furthermore, step S200 also includes the following sub-steps: Obtain all first and third target points between the first threshold line and the second threshold line, and mark them as target filtering points; Obtain the real-time target duration of the target filter points and mark it as the real-time filter duration; Get the average duration of real-time filtering and mark it as the average real-time filtering duration; The ultrasonic probe moves along the first vertical line above the target cable to obtain the position of evenly distributed intervals for real-time screening. The minimum real-time average filtering time is obtained and marked as the real-time location duration.

[0013] Furthermore, step S300 also includes the following sub-steps: The transmission speed of the ultrasonic wave in the insulation layer of the target cable at this time is obtained and marked as the real-time transmission speed. The real-time point thickness is obtained as follows: H = v1 × T1 ÷ 2; where H is the real-time point thickness, v1 is the real-time transmission speed, and T1 is the real-time point duration.

[0014] Furthermore, step S400 also includes the following sub-steps: Rotate the target cable 360° and obtain the real-time point thickness at each first degree interval; Obtain the average thickness of all real-time points and mark it as the average real-time insulation thickness. Obtain the minimum real-time insulation thickness at the specified point and mark it as the minimum real-time insulation thickness. The insulation thickness of power cables is detected by measuring the real-time point thickness, the real-time average insulation thickness, and the real-time minimum insulation thickness.

[0015] The beneficial effects of this invention are as follows: This invention obtains the real-time reflection duration of the power cable under test and an ultrasonic probe; obtains the real-time target duration through the real-time reflection duration; obtains a first drawn straight line through the real-time target duration; obtains a first target point, a second target point, and a third target point through the real-time target duration and the first drawn straight line; obtains a first threshold straight line based on the first target point and the second target point; obtains a second threshold straight line through the first target point and the third target point; obtains the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line; obtains the real-time point thickness through the real-time point duration; and detects the cable insulation layer thickness through the real-time point thickness. The advantages are that it solves the problem of systematic thickness measurement errors caused by the offset of the sound wave incident angle and the lengthening of the echo propagation path, eliminates abnormally large or small data, and improves the accuracy of the acquired data. This invention obtains the real-time location duration by using the real-time target duration, the first threshold line, and the second threshold line. Its advantage lies in excluding abnormally large or small data, thereby improving the accuracy of the obtained data. Attached Figure Description

[0016] Figure 1 This is a flowchart of the steps of the method of the present invention; Figure 2 This is a schematic diagram of the ultrasonic probe, the first vertical line, and the insulation layer of the target cable of the present invention. Figure 3 This is a schematic diagram of the first drawn straight line, the second target straight line, the third target straight line, the first threshold straight line, and the second threshold straight line of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1, please refer to Figure 1 As shown, this application provides an online method for detecting the thickness of the insulation layer of a power cable, comprising the following steps: Step S100: Obtain the real-time reflection duration through the power cable to be tested and the ultrasonic probe; Step S100 includes the following sub-steps: Step S101: Obtain the power cable to be tested and mark it as the target cable; Step S102: Set a reference bottom surface and mark it as the first reference surface; Step S103: Place the target cable above the first reference surface and make the target cable parallel to the first reference surface; Step S104: Above the target cable and the first reference plane, obtain a plane parallel to the first reference plane and mark it as the second reference plane; Step S105: On the second reference plane, obtain a straight line parallel to the target cable and mark it as the first cable straight line; Step S106: On the second reference plane, obtain a straight line perpendicular to the first cable line and mark it as the first perpendicular straight line; Step S107: Ensure the ultrasonic probe is always perpendicular to the first reference surface, then move the ultrasonic probe along the first vertical line above the target cable. The time from the generation of ultrasonic waves on the target cable surface to the first receipt of the reflected ultrasonic waves is marked as the real-time reflection time. When the cable and the probe are perfectly centered and the incident angle of the sound wave does not shift, the path is shortest, i.e., the real-time reflection time is the smallest. Therefore, the ultrasonic probe can be adjusted by the real-time reflection time to make the acquisition of the real-time reflection time of the insulation layer more accurate.

[0019] Step S200 involves obtaining the real-time target duration through real-time reflection duration; obtaining a first drawn straight line through the real-time target duration; obtaining a first target point, a second target point, and a third target point through the real-time target duration and the first drawn straight line; obtaining a first threshold straight line based on the first target point and the second target point; obtaining a second threshold straight line through the first target point and the third target point; and obtaining the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line. Step S200 includes the following sub-steps: Step S201: At any position of the ultrasonic probe, acquire a first number of real-time reflection durations and mark them as real-time target durations; Step S202: Establish a Cartesian coordinate system with the real-time target duration as the horizontal axis value, and mark it as the first target coordinate system; Step S203: Obtain the average of all real-time target durations and mark it as the average real-time duration; Step S204: Obtain the horizontal and vertical axes of the first target coordinate system and label them as the first horizontal axis and the first vertical axis, respectively; Step S205: Set the first drawn line as: X=b; where X is the horizontal axis value of the first target coordinate system, and b is the average real-time duration. Step S206: Draw the first drawing line in the first target coordinate system; For practical applications, please refer to Figure 2 As shown, for example, if the average real-time duration is 2.610μs, then the first line to be drawn is: X=2.610μs.

[0020] Step S207: Obtain the difference between the real-time target duration and the average real-time duration, and mark it as the real-time target difference; In step S208, if the real-time target difference is less than 0, the absolute value of the real-time target difference is marked as the first target difference; if the real-time target difference is equal to 0, the real-time target difference is marked as the second target difference; if the real-time target difference is greater than 0, the real-time target difference is marked as the third target difference.

[0021] Step S209: Mark the lengths of the first target difference, the second target difference, and the third target difference on the first horizontal axis as the first offset length; Step S210: If the real-time target difference is less than 0, starting from any point on the first drawing line, draw a point with a distance of a first offset length from the first drawing line in the negative direction of the first horizontal axis and in the perpendicular direction of the first drawing line, and mark it as the first target point; if the real-time target difference is equal to 0, draw any point on the first drawing line and mark it as the second target point; if the real-time target difference is greater than 0, starting from any point on the first drawing line, draw a point with a distance of a first offset length from the first drawing line in the positive direction of the first horizontal axis and in the perpendicular direction of the first drawing line, and mark it as the third target point; the first target point represents the real-time target difference less than the average real-time duration, the second target point represents the real-time target difference equal to the average real-time duration, and the third target point represents the real-time target difference greater than the average real-time duration; the data is visualized to facilitate observation and analysis of the distribution of real-time target duration; For practical applications, please refer to Figure 3 As shown, for example, if the real-time target difference is 2.603 μs, the obtained real-time target difference is 2.603 - 2.610 = -0.007 μs. The first offset length is 0.007 μs. Since -0.007 μs is less than 0, starting from any point on the first drawing line, a point is drawn 0.007 μs away from the first drawing line in the negative direction of the first horizontal axis and perpendicular to the first drawing line. This point is marked as the first target point. Please refer to [link to relevant documentation]. Figure 2 As shown, the first target point is obtained; similarly, the second and third target points are obtained.

[0022] Step S211: Mark the first target point and the second target point as the first set of points, set a straight line parallel to the first vertical axis, and make the number of the first set of points on the left and right sides of the line equal, and mark this straight line as the second target line. Step S212: Obtain the distance between the first drawn straight line and the second target straight line, and mark it as the first data distance; Step S213: Set a ratio, marked as the first set ratio; with the quartile screening method as a reference, and screening at 1.5 times the abnormal threshold, the first set ratio is set to 3. Step S214: Obtain the product of the first data distance and the first set ratio, and mark it as the first threshold distance; Step S215: To the left of the second target line, at a distance of the first threshold from the second target line, obtain a straight line parallel to the first vertical axis and mark it as the first threshold line; For practical applications, please refer to Figure 2 As shown, for example, the second target line is obtained as X=2.608μs; the distance between the first drawn line X=2.610μs and the second target line X=2.608μs is obtained as 0.002μs, then the first data distance is 0.002μs; the first threshold distance is: 0.002×3=0.006μs; to the left of the second target line, at a distance of 0.006μs from the second target line, a line parallel to the first vertical axis is obtained as X=2.602μs, then the first threshold line is X=2.602μs.

[0023] Step S216: Mark both the first target point and the third target point as the second group of points, set a straight line parallel to the first vertical axis, and make the number of second group points on the left and right sides of the line equal, and mark this line as the third target line; Step S217: Obtain the distance between the first drawn line and the third target line, and mark it as the second data distance; Step S218: Set a ratio, marked as the second set ratio; with the quartile screening method as a reference, and screening at 1.5 times the abnormal threshold, the second set ratio is set to 3; Step S219: Obtain the product of the second data distance and the second set ratio, and mark it as the second threshold distance; Step S220: To the right of the third target line, at a distance of the second threshold distance from the third target line, obtain a line parallel to the first vertical axis and mark it as the second threshold line; For practical applications, please refer to Figure 2 As shown, for example, the third target line is obtained as X=2.612μs; the distance between the first drawn line X=2.610μs and the third target line X=2.612μs is obtained as 0.002μs, then the second data distance is 0.002μs; the second threshold distance is: 0.002×3=0.006μs; to the left of the third target line, at a distance of 0.006μs from the third target line, the line parallel to the first vertical axis is obtained as X=2.618μs, then the second threshold line is X=2.618μs.

[0024] Step S221: Obtain all first target points and third target points between the first threshold line and the second threshold line, and mark them as target filtering points; For practical applications, please refer to Figure 3As shown, all first and third target points between the first threshold line X=2.602μs and the second threshold line X=2.618μs are obtained and marked as target screening points.

[0025] Step S222: Obtain the real-time target duration of the target filtering point and mark it as the real-time filtering duration; Step S223: Obtain the average real-time filtering duration and mark it as the average real-time filtering duration; Step S224: Move the ultrasonic probe along the first vertical straight line above the target cable to obtain the position of evenly distributed intervals and obtain the real-time screening time. Step S225: Obtain the minimum real-time screening time and mark it as the real-time point duration. When the cable and probe are absolutely centered and the incident angle of the sound wave does not shift, the path is shortest, that is, the real-time reflection time is the minimum. Therefore, the ultrasonic probe can be adjusted by the real-time reflection time to make the acquisition of the real-time reflection time of the insulation layer more accurate. Step S300: Obtain the real-time point thickness by measuring the real-time point duration; Step S300 includes the following sub-steps: Step S301: Obtain the transmission speed of the ultrasonic wave in the insulation layer of the target cable at this time, and mark it as the real-time transmission speed; Step S302, obtain the real-time point thickness as: H=v1×T1÷2; where H is the real-time point thickness, v1 is the real-time transmission speed, and T1 is the real-time point duration; In practical applications, if the transmission speed of the ultrasonic wave in the target cable insulation layer is 2300 m / s, then the real-time transmission speed is 2300 m / s, which is equivalent to 2.3 mm / μs. The real-time point thickness is obtained as: H = v1 × T1 ÷ 2 ≈ 3.00 mm. The calculation result is rounded to two decimal places. Units are consistent when calculating the real-time point thickness.

[0026] Step S400 involves detecting the cable insulation layer thickness using real-time point-based thickness measurements; step S400 includes the following sub-steps: Step S401: Rotate the target cable 360° and obtain the real-time point thickness at each first degree interval; that is, the insulation layer of the target cable around one circumference. Step S402: Obtain the average thickness of all real-time points and mark it as the average real-time insulation thickness. Step S403: Obtain the minimum value of the real-time point thickness and mark it as the minimum value of the real-time insulation thickness; Step S404: The insulation layer thickness of the power cable is detected by real-time point thickness, real-time average insulation thickness, and real-time minimum insulation thickness; the insulation layer is judged to be qualified based on the detected values. In practical applications, for example, if the insulation layer is set to 3mm, and the real-time point thickness, the minimum real-time insulation thickness, and the average real-time insulation thickness are all 3mm, then it indicates that the insulation layer thickness at this measurement location is qualified.

[0027] Example 2: This application also provides an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. The memory stores computer-readable instructions, and the processor can call the instructions in the memory. When the computer-readable instructions are executed by the processor, the steps of an online detection method for the insulation layer thickness of a power cable are performed to achieve the following functions: obtaining the real-time reflection duration through the power cable to be tested and the ultrasonic probe; obtaining the real-time target duration through the real-time reflection duration; obtaining a first drawn straight line through the real-time target duration; obtaining a first target point, a second target point, and a third target point through the real-time target duration and the first drawn straight line; obtaining a first threshold straight line based on the first target point and the second target point; obtaining a second threshold straight line through the first target point and the third target point; obtaining the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line; obtaining the real-time point thickness through the real-time point duration; and detecting the cable insulation layer thickness through the real-time point thickness.

[0028] Furthermore, when the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0029] Example 3: This application also provides a computer program product, which includes a computer program stored on a computer-readable storage medium. The computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute an online detection method for the insulation layer thickness of a power cable provided by the above methods. The method includes: obtaining real-time reflection duration through the power cable to be detected and an ultrasonic probe; obtaining a real-time target duration through the real-time reflection duration; obtaining a first drawn straight line through the real-time target duration; obtaining a first target point, a second target point, and a third target point through the real-time target duration and the first drawn straight line; obtaining a first threshold straight line based on the first target point and the second target point; obtaining a second threshold straight line through the first target point and the third target point; obtaining a real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line; obtaining a real-time point thickness through the real-time point duration; and detecting the cable insulation layer thickness through the real-time point thickness.

[0030] Example 4: This application also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program performs the steps described above in the online detection method for the insulation layer thickness of a power cable to achieve the following functions: obtaining the real-time reflection duration through the power cable to be tested and the ultrasonic probe; obtaining the real-time target duration through the real-time reflection duration; obtaining a first drawn straight line through the real-time target duration; obtaining a first target point, a second target point, and a third target point through the real-time target duration and the first drawn straight line; obtaining a first threshold straight line based on the first target point and the second target point; obtaining a second threshold straight line through the first target point and the third target point; obtaining the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line; obtaining the real-time point thickness through the real-time point duration; and detecting the cable insulation layer thickness through the real-time point thickness.

[0031] Based on the above description of the embodiments, the embodiments of the present invention can be provided as methods, systems, or computer program products. Based on this understanding, the above technical solutions, in essence or in terms of their contribution to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or certain parts of the embodiments.

[0032] In the embodiments provided in this application, it should be understood that the disclosed system or method can be implemented in other ways. The embodiments described above are merely illustrative. For example, the division of modules or units is only a logical functional division, and there may be other division methods in actual implementation. Furthermore, multiple modules or units may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interfaces. The indirect coupling or communication connection between systems, modules, and units may be electrical, mechanical, or other forms.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such 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 the embodiments of this application.

Claims

1. A method for online detection of insulation layer thickness in power cables, characterized in that, Includes the following steps: Step S100: Obtain the real-time reflection duration through the power cable to be tested and the ultrasonic probe; Step S200: Obtain the real-time target duration through the real-time reflection duration; obtain the first drawn straight line through the real-time target duration; obtain the first target point, the second target point, and the third target point through the real-time target duration and the first drawn straight line; obtain the first threshold straight line based on the first target point and the second target point; obtain the second threshold straight line through the first target point and the third target point; obtain the real-time point duration through the real-time target duration, the first threshold straight line, and the second threshold straight line. Step S300: Obtain the real-time point thickness by measuring the real-time point duration; Step S400: The thickness of the cable insulation layer is detected by real-time point thickness measurement.

2. The method for online detection of insulation layer thickness of power cables according to claim 1, characterized in that, Step S100 also includes the following sub-steps: Obtain the power cable to be inspected and mark it as the target cable; Define a reference bottom surface, and mark it as the first reference surface; Position the target cable above the first reference plane and make the target cable parallel to the first reference plane; Above the target cable and the first reference plane, obtain a plane parallel to the first reference plane and mark it as the second reference plane; On the second reference plane, obtain a straight line parallel to the target cable and mark it as the first cable straight line; On the second reference plane, obtain a straight line perpendicular to the first cable line and mark it as the first perpendicular straight line; The ultrasonic probe is always perpendicular to the first reference surface. Then, the ultrasonic probe is moved above the target cable along the first vertical line. The time from the generation of ultrasonic waves on the surface of the target cable to the first receipt of the reflected ultrasonic waves is marked as the real-time reflection time.

3. The method for online detection of insulation layer thickness of power cables according to claim 2, characterized in that, Step S200 also includes the following sub-steps: At any position of the ultrasonic probe, acquire the first number of real-time reflection durations and mark them as the real-time target durations; A Cartesian coordinate system is established with the real-time target duration as the horizontal axis value, and it is marked as the first target coordinate system; Obtain the average duration of all real-time targets and mark it as the average real-time duration; Obtain the horizontal and vertical axes of the first target coordinate system, and label them as the first horizontal axis and the first vertical axis, respectively; The first line to be drawn is defined as: X=b; where X is the horizontal axis value of the first target coordinate system, and b is the average real-time duration. Draw the first line in the first target coordinate system.

4. The method for online detection of insulation layer thickness of power cables according to claim 3, characterized in that, Step S200 also includes the following sub-steps: Obtain the difference between the real-time target duration and the average real-time duration, and mark it as the real-time target difference; If the real-time target difference is less than 0, the absolute value of the real-time target difference is marked as the first target difference; If the real-time target difference is equal to 0, mark the real-time target difference as the second target difference; If the real-time target difference is greater than 0, mark the real-time target difference as the third target difference.

5. The method for online detection of insulation layer thickness of power cables according to claim 4, characterized in that, Step S200 also includes the following sub-steps: The lengths of the first target difference, the second target difference, and the third target difference on the first horizontal axis are marked as the first offset length; If the real-time target difference is less than 0, starting from any point on the first drawing line, draw a point in the negative direction of the first horizontal axis and in the perpendicular direction of the first drawing line, with a distance of the first drawing line equal to the first offset length, and mark it as the first target point; If the real-time target difference is equal to 0, any point will be drawn on the first drawing line and marked as the second target point; If the real-time target difference is greater than 0, starting from any point on the first drawing line, draw a point in the positive direction of the first horizontal axis and in the perpendicular direction of the first drawing line, with a distance of the first drawing line equal to the first offset length, and mark it as the third target point.

6. The method for online detection of insulation layer thickness of power cables according to claim 5, characterized in that, Step S200 also includes the following sub-steps: Mark the first target point and the second target point as the first set of points, set a straight line parallel to the first vertical axis, and make the number of the first set of points on the left and right sides of the line equal, and mark this line as the second target line; Obtain the distance between the first drawn straight line and the second target straight line, and mark it as the first data distance; Set a ratio and mark it as the first set ratio; Obtain the product of the first data distance and the first set ratio, and mark it as the first threshold distance; To the left of the second target line, at a distance equal to the first threshold distance from the second target line, obtain a line parallel to the first vertical axis and mark it as the first threshold line.

7. The method for online detection of insulation layer thickness of power cables according to claim 6, characterized in that, Step S200 also includes the following sub-steps: Mark both the first target point and the third target point as the second group of points. Set a straight line parallel to the first vertical axis, and make the number of the second group of points on the left and right sides of the line equal. Mark this line as the third target line. Obtain the distance between the first drawn line and the third target line, and mark it as the second data distance; Set a ratio and mark it as the second set ratio; Obtain the product of the second data distance and the second set ratio, and mark it as the second threshold distance; To the right of the third target line, at a distance equal to the second threshold distance from the third target line, obtain a line parallel to the first vertical axis and mark it as the second threshold line.

8. The method for online detection of insulation layer thickness of power cables according to claim 7, characterized in that, Step S200 also includes the following sub-steps: Obtain all first and third target points between the first threshold line and the second threshold line, and mark them as target filtering points; Obtain the real-time target duration of the target filter points and mark it as the real-time filter duration; Get the average duration of real-time filtering and mark it as the average real-time filtering duration; The ultrasonic probe moves along the first vertical line above the target cable to obtain the position of evenly distributed intervals for real-time screening. The minimum real-time average filtering time is obtained and marked as the real-time location duration.

9. The method for online detection of insulation layer thickness of power cables according to claim 8, characterized in that, Step S300 also includes the following sub-steps: The transmission speed of the ultrasonic wave in the insulation layer of the target cable at this time is obtained and marked as the real-time transmission speed. The real-time point thickness is obtained as follows: H = v1 × T1 ÷ 2; where H is the real-time point thickness, v1 is the real-time transmission speed, and T1 is the real-time point duration.

10. The method for online detection of insulation layer thickness of power cables according to claim 9, characterized in that, Step S400 also includes the following sub-steps: Rotate the target cable 360° and obtain the real-time point thickness at each first degree interval; Obtain the average thickness of all real-time points and mark it as the average real-time insulation thickness. Obtain the minimum real-time insulation thickness at the specified point and mark it as the minimum real-time insulation thickness. The insulation thickness of power cables is detected by measuring the real-time point thickness, the real-time average insulation thickness, and the real-time minimum insulation thickness.

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