Cable accessory defect nondestructive testing device based on microwave reflection

Abstract

The invention discloses a nondestructive testing device for cable accessory defects based on microwave reflection, and relates to the technical field of defect detection, and the device comprises a microwave signal source, a power amplifier, a directional coupler, a detector, a data acquisition card and an upper computer which are connected in sequence; the microwave signal source is used for transmitting microwave signals; the power amplifier is used for performing power amplification on the microwave signal to obtain a microwave signal after power amplification; the directional coupler is used for sending the received microwave signal after power amplification to the detected cable accessory and sending a microwave reflection signal reflected by the detected cable accessory to the detector; the detector is used for detecting the microwave reflection signal to obtain an analog DC voltage signal; the data acquisition card is used for converting the analog DC voltage signal to obtain a reflection voltage; and the upper computer is used for determining a defect detection result of the detected cable accessory based on the reflection voltage. The defect detection precision of the cable accessory is improved.

Description

Technical Field

[0001] The present application relates to the technical field of defect detection, and in particular to a non-destructive detection device for cable accessory defects based on microwave reflection. Background Art

[0002] Cables, as a typical multi-layer composite insulation structure, are widely used in power grid construction due to their high elasticity, easy operation and maintenance, heat resistance, and excellent insulation properties. Statistics show that cable defects and failures in power supply and consumption systems are often caused by abnormalities and damage to cable accessories (connectors and terminals). Excluding external damage, the failure rate of cable accessories can reach as high as 70% of all line failures. Therefore, defect detection and monitoring of cable accessories has become a critical component of current power system operation and maintenance.

[0003] Currently, nondestructive testing for cable accessory defects primarily relies on methods such as partial discharge testing and ultrasonic testing. While partial discharge testing can identify typical cable defects using characteristic partial discharge parameters such as discharge inception voltage, average discharge volume, and discharge volume phase distribution spectrum, it is significantly susceptible to noise interference. Ultrasonic testing rapidly detects and accurately locates internal defects, but places high demands on sensor sensitivity and interference resistance. Furthermore, these nondestructive testing methods suffer from low accuracy.

[0004] Therefore, there is an urgent need for a high-precision detection device that can identify and locate internal defects of cable accessories online. Summary of the Invention

[0005] The purpose of this application is to provide a nondestructive detection device for cable accessory defects based on microwave reflection to solve the problem of low accuracy in cable accessory defect detection.

[0006] To achieve the above objectives, this application provides the following solutions:

[0007] In a first aspect, the present application provides a nondestructive detection device for cable accessory defects based on microwave reflection, comprising: a microwave signal source, a power amplifier, a directional coupler, a detector, a data acquisition card, and a host computer connected in sequence;

[0008] The microwave signal source is used to transmit microwave signals;

[0009] The power amplifier is used to amplify the power of the microwave signal to obtain a power-amplified microwave signal;

[0010] The directional coupler is used to send the received microwave signal after power amplification to the cable accessory under test, and send the microwave reflection signal reflected by the cable accessory under test to the detector;

[0011] The detector is used to detect the microwave reflection signal to obtain an analog DC voltage signal;

[0012] The data acquisition card is used to convert the analog DC voltage signal to obtain a reflected voltage;

[0013] The host computer is used to determine a defect detection result of the tested cable accessory based on the reflected voltage; the defect detection result is the presence of a defect or the absence of a defect.

[0014] In one embodiment, the cable accessory defect nondestructive detection device based on microwave reflection further includes: a DC voltage source; the DC voltage source is connected to the microwave signal source, the power amplifier, and the detector respectively;

[0015] The DC voltage source is used to convert 220V AC power into 12V DC power to provide operating voltage for the microwave signal source, the power amplifier and the detector.

[0016] In one embodiment, the cable accessory defect nondestructive detection device based on microwave reflection further includes: a rectangular waveguide; the rectangular waveguide is connected to the power amplifier and the directional coupler respectively;

[0017] The rectangular waveguide is used to transmit the microwave signal after power amplification.

[0018] In one embodiment, the microwave signal emitted by the microwave signal source is frequency-adjustable.

[0019] In one embodiment, the rectangular waveguide is connected to the input end of the directional coupler, and the directional coupler sends the received microwave signal after power amplification to the cable accessory under test through the coupling end.

[0020] In one embodiment, the detector is a broadband detector.

[0021] In one embodiment, determining a defect detection result of the tested cable accessory based on the reflected voltage includes:

[0022] Determining a relative value of a reflected voltage difference of the tested cable accessory based on the reflected voltage, a preset mean voltage, and a preset voltage error;

[0023] Based on the relative value of the reflected voltage difference, a defect detection result of the tested cable accessory is determined.

[0024] In one embodiment, the preset mean voltage is the mean of the reflected voltages of non-defective cable accessories, and the preset voltage error is the error of the reflected voltages of non-defective cable accessories.

[0025] In one embodiment, determining a relative value of a reflected voltage difference of a tested cable accessory based on the reflected voltage, a preset mean voltage, and a preset voltage error includes:

[0026] The relative value calculation formula of the reflected voltage difference is used to calculate the relative value of the reflected voltage difference of the cable accessory under test according to the reflected voltage, the preset mean voltage and the preset voltage error. The relative value calculation formula of the reflected voltage difference is:

[0027]

[0028] Where, P is the relative value of the reflected voltage difference of the tested cable accessories; U i is the reflected voltage of the tested cable accessories; is the preset mean voltage; U e is the preset voltage error.

[0029] In one embodiment, determining a defect detection result of the tested cable accessory based on a relative value of the reflected voltage difference includes:

[0030] Determine whether the relative value of the reflected voltage difference is greater than 100%;

[0031] If yes, the defect detection result of the tested cable accessory is that there is a defect;

[0032] If not, the defect detection result of the tested cable accessory is that there is no defect.

[0033] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0034] The present application discloses a nondestructive detection device for cable accessory defects based on microwave reflection, comprising: a microwave signal source, a power amplifier, a directional coupler, a detector, a data acquisition card, and a host computer connected in sequence. During detection, the microwave signal source transmits a microwave signal; the power amplifier amplifies the microwave signal to obtain a power-amplified microwave signal; the directional coupler transmits the received power-amplified microwave signal to the cable accessory under test, and transmits the microwave reflection signal reflected by the cable accessory under test to the detector; the detector detects the microwave reflection signal to obtain an analog DC voltage signal; the data acquisition card converts the analog DC voltage signal to obtain a reflection voltage; and the host computer determines the defect detection result of the cable accessory under test based on the reflection voltage. The present application utilizes microwave signals for cable accessory defect detection. Microwave signals can penetrate non-metallic materials. Any minor defects in the cable accessory will cause changes in the dielectric properties of the cable accessory, resulting in changes in the reflected voltage emission, thereby improving the accuracy of cable accessory defect detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic structural diagram of a device for nondestructive detection of cable accessory defects based on microwave reflection provided in one embodiment of the present application;

[0037] Figure 2 Schematic diagram of the relative values of the reflected voltage difference when the sample contains three types of defects.

[0038] Reference numerals:

[0039] Microwave signal source-1, power amplifier-2, directional coupler-3, detector-4, data acquisition card-5, host computer-6, tested cable accessories-7, DC voltage source-8, rectangular waveguide-9. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0041] The purpose of this application is to provide a nondestructive detection device for cable accessory defects based on microwave reflection, aiming to improve the accuracy of cable accessory defect detection.

[0042] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0043] In an exemplary embodiment, Figure 1 As shown, a nondestructive detection device for cable accessory defects based on microwave reflection is provided, comprising: a microwave signal source 1, a power amplifier 2, a directional coupler 3, a detector 4, a data acquisition card 5 and a host computer 6 connected in sequence.

[0044] The microwave signal source 1 is used to transmit microwave signals.

[0045] Specifically, the main function of the microwave signal source 1 is to convert the 12V DC power provided by the DC voltage source 8 into a high-frequency sinusoidal AC signal, and transmit a microwave signal with adjustable frequency as a signal source for non-destructive testing.

[0046] The power amplifier 2 is used to amplify the power of the microwave signal to obtain a power-amplified microwave signal.

[0047] Specifically, the main function of the power amplifier 2 is to amplify the power of the microwave signal to improve the penetration ability of the microwave signal into the thicker cable accessory 7 under test.

[0048] The directional coupler 3 is used to send the received microwave signal after power amplification to the cable accessory 7 under test, and send the microwave reflection signal reflected by the cable accessory 7 under test to the detector 4 .

[0049] The detector 4 is used to detect the microwave reflection signal to obtain an analog DC voltage signal.

[0050] The data acquisition card 5 is used to convert the analog DC voltage signal to obtain the reflected voltage.

[0051] Specifically, the data acquisition card's primary function is to collect the continuous analog DC voltage signal output by the detector, convert it into a discrete digital signal, the reflected voltage, and send it to a host computer programmed in LabVIEW. The analog DC voltage signal to be acquired is first discretized according to the sampling interval, then sampled and held. The analog signal amplitude is then discretized according to the discretized time series. The discretized amplitude is represented using a binary code with the minimum resolution. The discretized time and amplitude are then transmitted to the host computer via serial communication, resulting in the output digital signal, thus completing signal acquisition.

[0052] The host computer 6 is used to determine a defect detection result of the tested cable accessory based on the reflected voltage; the defect detection result is the presence of a defect or the absence of a defect.

[0053] Specifically, the host computer was developed based on LabVIEW software to interact with the hardware devices and complete data acquisition, reading, processing, and storage. The data acquisition card uses a single channel to collect the analog DC voltage signal output by the detector and then transmits the collected signal to the host computer, thereby enabling real-time reading and storage of microwave reflection signals.

[0054] As an optional implementation, the cable accessory defect nondestructive detection device based on microwave reflection further includes: a DC voltage source 8; the DC voltage source 8 is connected to the microwave signal source 1, the power amplifier 2 and the detector 4 respectively.

[0055] The DC voltage source 8 is used to convert 220V AC power into 12V DC power to provide operating voltage for the microwave signal source 1 , the power amplifier 2 and the detector 4 .

[0056] Specifically, the main function of the DC voltage source is to complete the AC / DC conversion function, converting 220V AC power into 12V DC power, providing operating voltage for the microwave source, power amplifier and detector.

[0057] As an optional implementation, the cable accessory defect nondestructive detection device based on microwave reflection further includes: a rectangular waveguide 9; the rectangular waveguide 9 is connected to the power amplifier 2 and the directional coupler 3 respectively.

[0058] The rectangular waveguide 9 is used to transmit the microwave signal after power amplification.

[0059] Specifically, the main function of the rectangular waveguide is to transmit microwave signals. It is made of metal material, has a rectangular inner cross-section, and is hollow inside. The microwave signal is confined in the rectangular waveguide, reducing the loss during the propagation process.

[0060] As an optional implementation manner, the microwave signal emitted by the microwave signal source is frequency-adjustable.

[0061] As an optional implementation, the rectangular waveguide 9 is connected to the input end of the directional coupler 3 , and the directional coupler 3 sends the received microwave signal after power amplification to the cable accessory 7 under test through the coupling end.

[0062] Specifically, this device uses only one waveguide probe to both transmit microwave signals and receive reflected microwave reflection signals, so a directional coupler is required. When both incident and reflected microwave signals exist in the rectangular waveguide, the directional coupler can separate the reflected microwave signals separately, so that the reflected microwave signals are not interfered with by the incident microwave signals.

[0063] As an optional implementation, the detector 4 is a broadband detector.

[0064] Specifically, the broadband detector receives the microwave reflection signal from the coupled end, converts it into an analog DC voltage, and uses the voltage of the microwave reflection signal to indicate its strength. The broadband detector then detects the peak value of the microwave reflection signal using diode envelope detection.

[0065] As an optional implementation, determining a defect detection result of the tested cable accessory based on the reflected voltage includes:

[0066] A relative value of a reflected voltage difference of the tested cable accessory is determined based on the reflected voltage, the preset mean voltage, and the preset voltage error.

[0067] Based on the relative value of the reflected voltage difference, the defect detection result of the tested cable accessory is determined.

[0068] As an optional implementation manner, the preset mean voltage is the mean of the reflected voltages of non-defective cable accessories, and the preset voltage error is the error of the reflected voltages of non-defective cable accessories.

[0069] As an optional implementation manner, determining a relative value of a reflected voltage difference of a tested cable accessory based on the reflected voltage, a preset mean voltage, and a preset voltage error includes:

[0070] The relative value calculation formula of the reflected voltage difference is used to calculate the relative value of the reflected voltage difference of the cable accessory under test according to the reflected voltage, the preset mean voltage, and the preset voltage error. The relative value calculation formula of the reflected voltage difference is:

[0071]

[0072] Where, P is the relative value of the reflected voltage difference of the tested cable accessories; U i is the reflected voltage of the tested cable accessories; is the preset mean voltage; U e is the preset voltage error.

[0073] As an optional implementation, determining a defect detection result of the tested cable accessory based on a relative value of the reflected voltage difference includes:

[0074] It is determined whether the relative value of the reflected voltage difference is greater than 100%.

[0075] If so, the defect detection result of the tested cable accessory is that there is a defect.

[0076] If not, the defect detection result of the tested cable accessory is that there is no defect.

[0077] Specifically, when the relative value of the reflected voltage difference is greater than 100%, it means that the reflected voltage difference (i.e., the difference between the reflected voltage of the tested cable accessory and the preset mean voltage) exceeds 1 times the system error (i.e., the preset voltage error), and presents a more obvious change in the detection curve, which can effectively determine the presence of defects.

[0078] Three types of defects, namely, conductive impurities, air gap defects, and moisture intrusion, were created at different locations on the same flat sample for comparative experiments. The relative values of the reflected voltage differences of the three types of defects in the sample are shown in Figure 2. Figure 2 shown.

[0079] according to Figure 2It can be seen that the relative values of the reflected voltage differences for the three different types of defects are significantly different. The reflected voltages for defects with conductive impurities and air gaps are higher than those for defects without defects, while the reflected voltage for defects with moisture ingress is lower than that for defects without defects. The order of reflected voltage is: defects with conductive impurities > air gaps > moisture ingress. The relative value of the reflected voltage difference for defects with conductive impurities exceeds 600%, for air gaps it is approximately 350%, and for moisture ingress it is approximately -550%. The absolute values of the relative values of the reflected voltage differences are all greater than 100%, thus effectively identifying the three different types of defects on the flat sample.

[0080] The device of this application has the following advantages:

[0081] 1. Non-contact detection: No physical contact with the cable accessories under test is required to avoid damage or interference.

[0082] 2. High penetration: can penetrate a variety of non-metallic materials, such as plastics, ceramics and composite materials.

[0083] 3. High precision: Provides high resolution and can detect tiny defects and subtle changes.

[0084] 4. Real-time detection: Able to obtain data in real time and quickly feedback test results.

[0085] 5. High safety: using low-power microwaves, harmless to human body and environment.

[0086] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the device and its core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A nondestructive detection device for cable accessory defects based on microwave reflection, characterized in that: The cable accessory defect nondestructive detection device based on microwave reflection comprises: a microwave signal source, a power amplifier, a directional coupler, a detector, a data acquisition card and a host computer connected in sequence; The microwave signal source is used to transmit microwave signals; The power amplifier is used to amplify the power of the microwave signal to obtain a power-amplified microwave signal; The directional coupler is used to send the received microwave signal after power amplification to the cable accessory under test, and send the microwave reflection signal reflected by the cable accessory under test to the detector; The detector is used to detect the microwave reflection signal to obtain an analog DC voltage signal; The data acquisition card is used to convert the analog DC voltage signal to obtain a reflected voltage; The host computer is used to determine a defect detection result of the tested cable accessory based on the reflected voltage; the defect detection result is the presence of a defect or the absence of a defect.

2. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 1 is characterized in that: The cable accessory defect nondestructive detection device based on microwave reflection further includes: a DC voltage source; the DC voltage source is connected to the microwave signal source, the power amplifier and the detector respectively; The DC voltage source is used to convert 220V AC power into 12V DC power to provide operating voltage for the microwave signal source, the power amplifier and the detector.

3. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 1 is characterized in that: The cable accessory defect nondestructive detection device based on microwave reflection further includes: a rectangular waveguide; the rectangular waveguide is connected to the power amplifier and the directional coupler respectively; The rectangular waveguide is used to transmit the microwave signal after power amplification.

4. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 1, characterized in that: The microwave signal emitted by the microwave signal source is frequency-adjustable.

5. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 3 is characterized in that: The rectangular waveguide is connected to the input end of the directional coupler, and the directional coupler sends the received microwave signal after power amplification to the cable accessory under test through the coupling end.

6. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 1, characterized in that: The detector is a broadband detector.

7. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 1, characterized in that: Determining a defect detection result of the tested cable accessory based on the reflected voltage includes: Determining a relative value of a reflected voltage difference of the tested cable accessory based on the reflected voltage, a preset mean voltage, and a preset voltage error; Based on the relative value of the reflected voltage difference, a defect detection result of the tested cable accessory is determined.

8. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 7, characterized in that: The preset mean voltage is the mean of the reflected voltage of a non-defective cable accessory, and the preset voltage error is the error of the reflected voltage of a non-defective cable accessory.

9. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 8, characterized in that: Determining a relative value of a reflected voltage difference of the tested cable accessory based on the reflected voltage, a preset mean voltage, and a preset voltage error includes: The relative value calculation formula of the reflected voltage difference is used to calculate the relative value of the reflected voltage difference of the cable accessory under test according to the reflected voltage, the preset mean voltage and the preset voltage error. The relative value calculation formula of the reflected voltage difference is: Where, P is the relative value of the reflected voltage difference of the tested cable accessories; U i is the reflected voltage of the tested cable accessories; is the preset mean voltage; U e is the preset voltage error.

10. The nondestructive detection device for cable accessory defects based on microwave reflection according to claim 7, characterized in that: Determining a defect detection result of the tested cable accessory based on a relative value of the reflected voltage difference includes: Determine whether the relative value of the reflected voltage difference is greater than 100%; If yes, the defect detection result of the tested cable accessory is that there is a defect; If not, the defect detection result of the tested cable accessory is that there is no defect.

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