Cable fault detection device based on terahertz waves

Abstract

The utility model discloses a cable fault detection device based on terahertz waves, which relates to the technical field of power equipment fault detection and comprises a box body, a quantum cascade laser, a terahertz wave receiving unit, a signal processing unit, a single chip microcomputer module, a storage unit, a display unit and a power supply module. The quantum cascade laser, the terahertz wave receiving unit, the signal processing unit, the single chip microcomputer module, the storage unit and the power supply module are arranged in the box body, and the display unit is arranged on the upper surface of the box body; the quantum cascade laser is electrically connected with the single chip microcomputer module and is used for emitting terahertz waves to a detection object; the terahertz wave receiving unit is used for receiving terahertz wave signals reflected back from a detection object and converting the terahertz wave signals into electric signals. According to the utility model, the problems of limited detection precision, insufficient weak fault signal detection capability and low detection efficiency of the existing detection device can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of power equipment fault detection, and particularly relates to a cable fault detection device based on terahertz waves. Background Art

[0002] In today's era of high dependence on electronic devices and complex line systems, the stable operation of fields such as power transmission and communication networks is of crucial importance. Once a device or line in these systems fails, serious consequences will occur. For example, a power supply interruption will affect industrial production and residents' lives, and a communication line failure will cause information transmission to be blocked, resulting in economic losses and social inconveniences. Therefore, efficient and accurate fault detection technology has become the key to ensuring the stable operation of the system. Currently, in the field of power transmission, the commonly used fault location methods are the impedance method and the traveling wave method. The impedance method estimates the fault location by measuring the line impedance from the fault point to the measurement end. However, this method is easily affected by factors such as line parameters and load changes, and it is often difficult to guarantee the positioning accuracy in long-distance transmission lines or complex power grid structures. The traveling wave method determines the fault location by using the propagation characteristics of the traveling wave generated by the fault on the transmission line. Although it has certain progress compared with the impedance method, in practical applications, the propagation of the traveling wave will be interfered by factors such as line distribution parameters and fault types, resulting in difficulties in extracting and analyzing the traveling wave signal. Especially for weak fault signals, it is difficult to achieve accurate fault location. In terms of communication line detection, an optical time domain reflectometer (OTDR) is a commonly used device for detecting fiber optic line faults. It injects optical pulses into the optical fiber and measures the reflected optical signal to judge the state and fault location of the optical fiber. However, for some minor faults in the optical fiber, such as microbend loss and local stress concentration, the detection sensitivity of the OTDR is limited, and these potential faults cannot be detected in a timely and accurate manner. In addition, for some special optical fiber materials or complex optical fiber network structures, the detection effect of the OTDR will also be affected.

[0003] As an electromagnetic wave between microwave and infrared light, terahertz wave has a frequency range of 0.1 - 10 THz and has a series of unique characteristics that are extremely suitable for fault location detection. First of all, terahertz wave has strong penetrability. It can easily penetrate many traditional materials, such as plastics, ceramics, papers, etc. In the detection of insulating materials of power equipment, terahertz wave can penetrate the insulating layer and detect internal defects or damages, while traditional detection methods often have difficulty in doing this. For optical fibers in communication lines, terahertz wave can also penetrate the cladding of the optical fiber and detect the condition inside the core, effectively making up for the deficiency of OTDR in detecting tiny faults. Secondly, the photon energy of terahertz wave is relatively low, which makes the damage to the detected object extremely small, even negligible, and is very suitable for non-destructive testing of some sensitive materials or precision equipment. In the fields of power transmission and communication, the materials of many devices and lines are extremely sensitive to the damage degree of detection means, and this characteristic of terahertz wave makes it an ideal detection tool. Moreover, the wavelength of terahertz wave is short, which can provide high spatial resolution. Compared with traditional detection methods, terahertz wave can detect smaller defects or faults, and can be used to detect tiny cracks, holes and other faults. In communication lines, for some nano-level defects, terahertz wave detection technology can more accurately locate the fault location and improve the accuracy and reliability of detection.

[0004] In addition, there are significant differences in the absorption and scattering characteristics of terahertz wave by different substances. By analyzing the signal changes after the interaction between terahertz wave and substances, information about the structure and composition of substances can be obtained, which helps to judge the type and location of faults. In power equipment, when insulating materials age or get damp, their absorption and scattering characteristics of terahertz wave will change. By detecting these changes, the state and fault conditions of insulating materials can be accurately judged.

[0005] To sum up, although the existing cable fault location detection devices can meet some detection requirements to a certain extent, there are still problems such as limited detection accuracy, insufficient detection ability for weak fault signals, low detection efficiency, poor adaptability to complex environments, and high equipment costs. And terahertz wave technology has broad application prospects for the fault detection of insulating materials. Therefore, developing a cable fault detection device based on terahertz wave has important practical significance for improving the reliability and stability of systems such as power transmission and communication networks. Summary of the Utility Model

[0006] The technical problem to be solved by this utility model is to provide a cable fault detection device based on terahertz wave to solve the problems of limited detection accuracy, insufficient detection ability for weak fault signals, and low detection efficiency existing in the existing detection devices.

[0007] To solve the above technical problems, the present utility model adopts the following technical solutions:

[0008] A cable fault detection device based on terahertz waves, comprising a box body, a quantum cascade laser, a terahertz wave receiving unit, a signal processing unit, a single-chip microcomputer module, a storage unit, a display unit and a power supply module; the quantum cascade laser, the terahertz wave receiving unit, the signal processing unit, the single-chip microcomputer module, the storage unit and the power supply module are arranged inside the box body, and the display unit is arranged on the upper surface of the box body; the quantum cascade laser is electrically connected to the single-chip microcomputer module and is used to emit terahertz waves to the detection object; the terahertz wave receiving unit is used to receive the terahertz wave signal reflected from the detection object and convert the terahertz wave signal into an electrical signal; the input end of the signal processing unit is electrically connected to the output end of the terahertz wave receiving unit and is used to perform signal amplification and filtering processing on the electrical signal; the input end of the single-chip microcomputer module is electrically connected to the output end of the signal processing unit and is used to receive the electrical signal processed by the signal processing unit and convert it into a digital signal; the single-chip microcomputer module is electrically connected to the storage unit, the single-chip microcomputer module is built-in with an algorithm model, the storage unit is built-in with standard parameter information, and the single-chip microcomputer module is used to convert the digital signal into fault information according to the algorithm model and in combination with the standard parameter information in the storage unit; the display unit is electrically connected to the single-chip microcomputer module and is used to display the fault information; the power supply module is used to provide a working voltage.

[0009] The beneficial effects of the present utility model are:

[0010] The cable fault detection device based on terahertz waves provided by the present utility model places the detection device in a suitable position, generates terahertz waves with a specific frequency and power through a quantum cascade laser, and directs the terahertz waves to the cable under test. The internal substances of the cable under test reflect the terahertz waves back. The terahertz wave receiving unit receives the reflected terahertz waves and converts the terahertz wave signal into an electrical signal, which is sent to the signal processing unit. After the signal processing unit amplifies and filters the electrical signal, it is sent to the single-chip microcomputer module. The single-chip microcomputer module converts the electrical signal into a digital signal, extracts features from the digital signal through its built-in algorithm model and in combination with the standard parameter information in the storage unit, obtains feature parameters related to faults, such as the amplitude, frequency, phase, etc. of the signal, compares the feature parameters with the standard information in the storage unit, and finally obtains the fault type and location of the cable under test. The display unit visually displays the fault information. Thus, this fault detection device utilizes the characteristics of short terahertz wave wavelength and high spatial resolution to accurately detect tiny defects or faults inside the cable, greatly improving the fault location accuracy, achieving precise positioning, reducing the error range. At the same time, it can also quickly complete the cable fault detection, greatly shortening the detection time, reducing the cable outage duration, improving the reliability of the power and communication networks, and reducing economic losses. Description of the Drawings

[0011] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model.

[0012] Figure 2 It is a principle block diagram of an embodiment of the present utility model.

[0013] Figure 3 It is a circuit diagram of the single-chip microcomputer module of an embodiment of the present utility model.

[0014] Figure 4 It is a circuit diagram of the quantum cascade laser of an embodiment of the present utility model.

[0015] Figure 5 It is a circuit diagram of the terahertz wave receiving unit and the signal processing unit of an embodiment of the present utility model.

[0016] Figure 6 It is a circuit diagram of the storage unit of an embodiment of the present utility model.

[0017] Figure 7 It is a circuit diagram of the USB module of an embodiment of the present utility model.

[0018] Figure 8 It is a circuit diagram of the communication module of an embodiment of the present utility model.

[0019] Figure 9 It is a circuit diagram of the display unit of an embodiment of the present utility model.

[0020] Figure 10 It is a circuit diagram of the temperature sensor of an embodiment of the present utility model.

[0021] The reference numerals in the figure are: 1, box body; 11, ventilation grille; 2, quantum cascade laser; 3, terahertz wave receiving unit; 31, detector; 32, receiving antenna; 4, signal processing unit; 5, single-chip microcomputer module; 6, storage unit; 7, display unit; 8, power supply module; 81, storage battery; 82, solar photovoltaic panel; 9, USB module; 91, interface end; 10, communication module; 101, connector. Detailed implementation manners

[0022] The present utility model will be described below with reference to the accompanying drawings. The specific implementation manners described herein are only for explaining and understanding the present utility model, and are not used to limit the present utility model. Without departing from the design spirit of the present utility model, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present utility model shall fall within the protection scope of the present utility model.

[0023] As Figures 1 to 10As shown in the figure, the cable fault detection device based on terahertz waves in this embodiment includes a box body 1, a quantum cascade laser 2, a terahertz wave receiving unit 3, a signal processing unit 4, a single-chip microcomputer module 5, a storage unit 6, a display unit 7, and a power supply module 8.

[0024] Among them, the quantum cascade laser 2, the terahertz wave receiving unit 3, the signal processing unit 4, the single-chip microcomputer module 5, the storage unit 6, and the power supply module 8 are all arranged inside the box body 1, and the display unit 7 is arranged on the upper surface of the box body 1.

[0025] The quantum cascade laser 2 is electrically connected to the single-chip microcomputer module 5. The quantum cascade laser 2 can generate terahertz waves with specific frequencies and intensities. Its terahertz wave emitter is arranged on the surface of the box body 1 and is used to emit terahertz waves to the detection object (cable). The quantum cascade laser 2 is represented by U20 in the circuit.

[0026] The terahertz wave receiving unit 3 is used to receive the terahertz wave signals reflected from the detection object and convert the terahertz wave signals into electrical signals for subsequent processing. The terahertz wave receiving unit 3 in this embodiment includes a detector 31 and a receiving antenna 32 connected to the detector 31. The receiving antenna 32 is arranged outside the box body 1 and can efficiently receive and collect the terahertz wave signals reflected from the object to be measured and transmit them to the detector 31. The detector 31 (represented by U10 in the circuit) is arranged inside the box body 1, and the detector 31 is used to convert the received terahertz wave signals into electrical signals.

[0027] The input end of the signal processing unit 4 is electrically connected to the output end of the terahertz wave receiving unit 3 and is used to perform signal amplification and filtering processing on the electrical signals. The input end of the signal processing unit 4 is electrically connected to the output end of the detector 31. The signal processing unit 4 includes a plurality of capacitors, a plurality of resistors, and an LM385 amplifier (represented by U11 in the circuit).

[0028] The input end of the single-chip microcomputer module 5 is electrically connected to the output end of the signal processing unit 4 and is used to receive the electrical signals processed by the signal processing unit 4 and convert them into digital signals. The single-chip microcomputer module 5 in this embodiment uses a single-chip microcomputer module with an STC15W4K56S4 single-chip microcomputer as the core. This single-chip microcomputer has an ADC pin and has the function of converting electrical signals (analog signals) into digital signals.

[0029] The single-chip microcomputer module 5 is electrically connected to the storage unit 6. The single-chip microcomputer module 5 has an algorithm model built-in, and the storage unit 6 has standard parameter information built-in. The single-chip microcomputer module 5 is used to convert the digital signals into fault information according to the algorithm model and in combination with the standard parameter information in the storage unit 6. The storage unit 6 in this embodiment uses a W25Q64 chip (represented by U5 in the circuit), and the standard parameters stored therein include parameters such as the dielectric constant and loss tangent of the cable, as well as fault samples.

[0030] The algorithm model built in the single-chip microcomputer module 5 of this embodiment combines the standard parameters stored in the storage unit 6 to extract the characteristic parameters and classify the faults of the signal. Among them,

[0031] The extraction of characteristic parameters includes:

[0032] 1. Extraction of signal attenuation coefficient (amplitude parameter), specifically:

[0033] According to the time t when the first wave of the reflected signal reaches the receiver, and combined with the formula L = c * t / 2n (c is the speed of terahertz wave in vacuum, n is the refractive index of the cable medium), calculate the fault distance L, that is, calculate the fault location.

[0034] Compare the amplitude A0 of the transmitted signal and the amplitude AL of the received signal, and calculate the signal attenuation coefficient α (unit: dB / m). The calculation formula is:

[0035] α = (1 / L) * ln(A0 / AL),

[0036] Function: Reflect the attenuation degree of the signal amplitude, and be used to judge the insulation aging or material deterioration degree of the cable.

[0037] 2. Frequency parameter extraction, specifically:

[0038] Perform a fast Fourier transform (FFT) on the received signal, convert the received signal into a frequency-domain spectrum, obtain the amplitudes of each frequency component, and then determine the frequency point with the largest amplitude in the spectrum. This maximum frequency point is the fault spectrum peak frequency f.

[0039] Function: Identify the characteristic frequency of the cable fault type.

[0040] 3. Phase parameter extraction, specifically:

[0041] Perform FFT on the received signal x[n] to obtain the frequency-domain signal X[k].

[0042] Inverse FFT the frequency-domain signal X[k] to obtain the analytic signal z[n].

[0043] Calculate the phase spectrum θ[n] through the analytic signal. The formula is: θ[n] = arctan(Re[z[n]] / Im[z[n]]).

[0044] Calculate the phase distortion rate θdistortion through the phase spectrum θ[n]. The calculation formula is:

[0045]

[0046] Among them, θactual[n] is the actually measured phase spectrum; θideal[n] is the phase spectrum of the theoretical lossless cable; N is the signal length.

[0047] Function: Quantify the phase distortion during signal propagation, and be used to detect the uniformity or local defects of insulating materials.

[0048] In this way, the extraction of fault characteristic parameters such as the amplitude, frequency, and phase of the signal is realized.

[0049] Fault classification: Compare the extracted characteristic parameters with the standard parameters in the storage unit 6 to obtain the fault type, specifically:

[0050] Cable insulation aging, and its condition is: θdistortion > 15°, α > 0.3 dB / m.

[0051] Partial discharge, and its condition is: f ∈ [0.9, 1.1] THz.

[0052] Mechanical damage, and its condition is: L < 5 m and θdistortion > 20°.

[0053] In this way, the category of the fault can be obtained.

[0054] It should be noted that the above steps, formulas, calculation methods, and judgment methods all belong to the conventional technical means in this field.

[0055] The display unit 7 is electrically connected to the single-chip microcomputer module 5 and is used to display fault information. The display unit 7 in this embodiment adopts an XPT2046 touch screen (represented by J5 in the circuit), which provides an interaction interface for the operator. On the one hand, it can display the detection results, including information such as the fault location, fault type, and detection signal waveform; on the other hand, the operator can set detection parameters through this unit, such as the terahertz wave emission frequency, detection time interval, etc., to realize the control operation of the entire detection device.

[0056] The power supply module 8 is used to provide the working voltage. The power supply module 8 in this embodiment includes a storage battery 81 and a solar photovoltaic panel 82. Among them, the storage battery 81 is arranged in the box body 1, and the solar photovoltaic panel 82 is arranged on the surface of the box body 1. The solar photovoltaic panel 82 can convert solar energy into electrical energy under light conditions and charge the storage battery 81 to provide stable power supply for the entire device. A power switch is arranged on the surface of the box body 1.

[0057] In use, detection parameters are set through the display unit 7, such as terahertz wave emission frequency, detection cable type, etc. At the same time, the detection device is placed in a suitable position. The single-chip microcomputer module 5 controls the quantum cascade laser 2 to work, generates terahertz waves with corresponding frequencies and powers according to the set parameters, and the terahertz waves are directionally emitted onto the object to be measured (cable) by its emitter. The terahertz waves interact with the substances inside the object to be measured (cable), generating reflections. The receiving antenna 32 of the terahertz wave receiving unit 3 receives the reflected terahertz wave signals and transmits them to the detector 31. The detector 31 converts the terahertz wave signals into weak electrical signals (analog signals), and then transmits them to the signal processing unit 4 for processing. The signal processing unit 4 amplifies and filters the electrical signals, and sends the processed electrical signals to the single-chip microcomputer module 5. The single-chip microcomputer module 5 converts the electrical signals into digital signals, extracts features from the digital signals through its built-in algorithm model and in combination with the standard parameter information in the storage unit, and obtains feature parameters related to faults, such as the amplitude, frequency, and phase of the signals. The feature parameters are compared with the standard information in the storage unit, and finally the fault type and location of the cable to be measured (i.e., fault information) are obtained. The display unit 7 visually displays the fault information, facilitating the staff to know the fault information.

[0058] Moreover, the fault detection device further includes a USB module 9 and a communication module 10 connected to the single-chip microcomputer module 5.

[0059] Among them, the USB module 9 includes a USB interface circuit and a USB-to-serial port circuit. The interface end 91 of the USB interface circuit (i.e., the jack for inserting the USB data cable plug) is arranged on the surface of the box body 1. Its output end is electrically connected to the input end of the USB-to-serial port circuit, and the output end of the USB-to-serial port circuit is electrically connected to the input end of the single-chip microcomputer module 5. Among them, the USB interface circuit uses a MINI_USB chip (represented by J1 in the circuit), and the USB-to-serial port circuit uses a CH340G chip (represented by U2 in the circuit). The USB-to-serial port circuit is used to convert the electrical levels between the single-chip microcomputer module 5 and external devices into communication levels that can be commonly recognized by both parties. In use, external devices can be connected through the USB module 9 using a USB data cable, and the data generated by the single-chip microcomputer module 5 can be sent to the external device for data storage. In the circuit, the USB interface circuit is also connected to an AMS1117-3.3V voltage regulator chip (represented by U1 in the circuit). After connecting to an external device through the USB data cable, such as a computer host, under the action of the AMS1117-3.3V voltage regulator chip and its peripheral circuits, the 5V voltage can be converted into 3.3V voltage to supply power to the entire device.

[0060] The communication module 10 of this embodiment includes a WiFi module and a serial communication module. Among them, the WiFi module uses an ESP8266_01 chip (denoted as J10 in the circuit), which can connect to a wireless network (WiFi) and wirelessly transmit the data generated by the single-chip microcomputer module 5 to the mobile terminal. The serial communication module is an RS485 serial communication module, which includes a MAX485 chip (denoted as U4 in the circuit) and a connector 101 (denoted as J12 in the circuit). The connector 101 is arranged on the surface of the box body 1 and connects the single-chip microcomputer module 5 and the PC terminal through the RS485 data bus, thereby realizing data transmission.

[0061] Finally, a temperature sensor of model DS18B20 (denoted as J7 in the circuit) connected to the single-chip microcomputer module 5 is arranged in the box body 1 for detecting the temperature inside the box body 1, and a ventilation grid 11 is arranged on the surface of the box body 1 to play a role in heat dissipation.

[0062] In summary, the cable fault detection device based on terahertz waves of the present utility model utilizes the characteristics of short terahertz wave wavelength and high spatial resolution to accurately detect tiny defects or faults inside the cable, greatly improving the fault location accuracy, achieving precise positioning, reducing the error range. At the same time, it can also quickly complete the cable fault detection, greatly shortening the detection time, reducing the cable outage duration, improving the reliability of the power and communication networks, and reducing economic losses.

Claims

1. A cable fault detection device based on terahertz waves, characterized in that: It includes a box body (1), a quantum cascade laser (2), a terahertz wave receiving unit (3), a signal processing unit (4), a single-chip microcomputer module (5), a storage unit (6), a display unit (7) and a power supply module (8); among them, the quantum cascade laser (2), the terahertz wave receiving unit (3), the signal processing unit (4), the single-chip microcomputer module (5), the storage unit (6) and the power supply module (8) are arranged inside the box body (1), and the display unit (7) is arranged on the upper surface of the box body (1); the quantum cascade laser (2) is electrically connected to the single-chip microcomputer module (5) and is used to emit terahertz waves to the detection object; the terahertz wave receiving unit (3) is used to receive the terahertz wave signal reflected from the detection object and convert the terahertz wave signal into an electrical signal; the input end of the signal processing unit (4) is electrically connected to the output end of the terahertz wave receiving unit (3) and is used to perform signal amplification and filtering processing on the electrical signal; the input end of the single-chip microcomputer module (5) is electrically connected to the output end of the signal processing unit (4) and is used to receive the electrical signal processed by the signal processing unit (4) and convert it into a digital signal; the single-chip microcomputer module (5) is electrically connected to the storage unit (6). The single-chip microcomputer module (5) has an algorithm model built in, and the storage unit (6) has standard parameter information built in. The single-chip microcomputer module (5) is used to convert the digital signal into a fault message according to the algorithm model and in combination with the standard parameter information in the storage unit (6); the display unit (7) is electrically connected to the single-chip microcomputer module (5) and is used to display the fault message; the power supply module (8) is used to provide the working voltage.

2. The cable fault detection device based on terahertz waves according to claim 1, characterized in that: The terahertz wave receiving unit (3) includes a detector (31) and a receiving antenna (32) connected to the detector (31). The receiving antenna (32) is arranged outside the box body (1) and is used to receive the reflected terahertz waves. The detector (31) is arranged inside the box body (1) and is used to convert the terahertz wave signal into an electrical signal, and its output end is electrically connected to the input end of the signal processing unit (4).

3. The cable fault detection device based on terahertz waves according to claim 1, characterized in that: It also includes a USB module (9) connected to the single-chip microcomputer module (5). The USB module (9) includes a USB interface circuit and a USB to serial port circuit. The interface end (91) of the USB interface circuit is arranged on the surface of the box body (1), and its output end is electrically connected to the input end of the USB to serial port circuit. The output end of the USB to serial port circuit is electrically connected to the input end of the single-chip microcomputer module (5).

4. The cable fault detection device based on terahertz waves according to claim 1, characterized in that: It also includes a communication module (10) electrically connected to the single-chip microcomputer module (5). The communication module (10) includes a WiFi module and a serial port communication module.

5. The cable fault detection device based on terahertz waves according to claim 1, characterized in that: The power supply module (8) includes a storage battery (81) and a solar photovoltaic panel (82). The storage battery (81) is arranged inside the box body (1), and the solar photovoltaic panel (82) is arranged on the surface of the box body (1) and is used to charge the storage battery (81).

6. The cable fault detection device based on terahertz waves according to claim 1, characterized in that: Ventilation grilles (11) are arranged on the surface of the box body (1).

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