Comprehensive positioning device for low-voltage cable

Abstract

The invention relates to a low-voltage cable comprehensive positioning device, which comprises a signal transmitting unit, an inductive coupler, a signal transmission path and a signal receiving unit, and is characterized in that the inductive coupler comprises a transmitting end signal injection coupler and a receiving end signal extraction coupler, and the signal transmitting unit generates a high-frequency test signal; the transmitting end signal injection coupler injects a test signal into a cable core in a cable bundle ground coupling injection mode, the receiving end signal extraction coupler extracts a high-frequency test signal in the cable core, and the signal receiving unit carries out processing and result judgment according to the extracted signal so as to determine the fault position of the cable. And the signal transmission path realizes signal transmission among the signal transmitting unit, the inductive coupler and the signal receiving unit. According to the invention, through injection and extraction of the high-frequency test signal, the fault position of the cable can be rapidly determined, and the fault processing efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of transformer substations, and in particular to a low-voltage cable integrated positioning device. Background Art

[0002] In the construction and maintenance of substations, the wiring of low-voltage cables and their fault detection are crucial technical links. The fault location and direction detection of low-voltage cables play a key role in ensuring the stable operation of the power system. Since low-voltage cables are widely used in substations, urban power grids and industrial power consumption, the health of their operating status is directly related to the safety and stability of the entire urban power grid.

[0003] At present, there are several main problems in the field of low-voltage cable fault location:

[0004] Lack of effective equipment support: In the existing low-voltage cable fault location work, workers often lack specialized equipment to assist in positioning, which results in the fault detection work relying on the experience and technical level of the workers.

[0005] Traditional methods are inefficient: Traditional cable fault location methods rely on the staff's experience or use complex underground pipeline detection equipment. These methods usually require staff to observe the cable layout with the naked eye or use simple response instruments, which is not only time-consuming and labor-intensive, but also inefficient and difficult to guarantee accuracy.

[0006] Existing equipment on the market has single functions: Although there are some cable tracking and positioning instruments on the market, these instruments often only have a single signal transmission or reception function and lack the ability to identify and detect the cable direction in multiple dimensions.

[0007] Complex on-site environment and diverse cable types: In complex on-site environments and facing cables of different types and specifications, existing positioning tools and methods are often difficult to adapt, making fault location more difficult.

[0008] Therefore, in response to the above problems, it is necessary to research and develop a new type of low-voltage cable comprehensive positioning device, which can provide efficient and accurate fault positioning function, and at the same time has the ability to identify and detect the cable direction in multiple dimensions to adapt to complex field environments and the diversity of cable types, thereby improving the efficiency and accuracy of low-voltage cable fault positioning. Summary of the invention

[0009] The purpose of the present invention is to propose a low-voltage cable comprehensive positioning device, which can provide efficient and accurate fault positioning function, and at the same time has the ability to identify and detect the cable direction in multiple dimensions to adapt to complex field environments and the diversity of cable types, thereby improving the efficiency and accuracy of low-voltage cable fault positioning.

[0010] To achieve the above object, the present invention provides a low-voltage cable integrated positioning device, comprising a signal transmitting unit, an inductive coupler, a signal transmission path and a signal receiving unit;

[0011] The inductive coupler comprises a transmitting end signal injection coupler and a receiving end signal extraction coupler;

[0012] The signal transmitting unit is used to generate a high-frequency test signal injected into the cable;

[0013] The transmitting end signal injection coupler is used to inject the high-frequency test signal generated by the signal transmitting unit into the cable core in a cable bundle-to-ground coupling injection manner;

[0014] The receiving end signal extraction coupler is used to extract the high-frequency test signal coupled into the cable core;

[0015] The signal receiving unit is used to perform signal processing and result determination according to the high-frequency test signal extracted by the receiving-end signal extraction coupler to determine the fault location of the cable;

[0016] The signal transmission path is used to realize the signal transmission channel between the signal transmitting unit and the inductive coupler and between the inductive coupler and the signal receiving unit.

[0017] Preferably, the signal transmitting unit comprises:

[0018] The front-end signal simulation module is used to perform algorithm processing and control signal output according to signal requirements, thereby generating high-frequency test signals;

[0019] The digital-to-analog converter is connected to the front-end signal simulation module and is used to convert the digital signal into an analog high-frequency test signal.

[0020] Preferably, the signal transmitting unit further includes:

[0021] The bandpass filter is used to perform bandpass filtering on the analog high-frequency test signal to ensure that the generated high-frequency test signal is within the frequency band of 150kHz to 15MHz.

[0022] Preferably, the signal transmitting unit further includes:

[0023] The automatic gain control circuit is used to adjust the signal gain of the analog high-frequency test signal output by the bandpass filter.

[0024] Preferably, the signal transmitting unit further includes:

[0025] The differential amplifier circuit is used to differentially amplify the analog high-frequency test signal output by the automatic gain control circuit.

[0026] Preferably, the signal transmitting unit further includes:

[0027] The adaptive impedance matching circuit is used to adjust the output impedance of the signal transmitting unit according to the change of the power line impedance, so that the end of the signal transmitting unit connected to the power line exhibits a constant impedance value, and the analog high-frequency test signal after differential amplification by the differential amplifier circuit passes through the adaptive impedance matching circuit and is input into the transmitting end signal injection coupler.

[0028] Preferably, the signal receiving unit comprises:

[0029] The automatic gain control module is used to adjust the gain of the analog high-frequency test signal extracted by the receiving end signal extraction coupler to facilitate signal processing and result determination to determine the fault location of the cable.

[0030] Preferably, the signal receiving unit comprises:

[0031] The bandpass filter is used to filter the high-frequency test signal output by the automatic gain control module to facilitate signal processing and result determination, so as to determine the fault location of the cable.

[0032] Preferably, the signal receiving unit comprises:

[0033] An analog-to-digital converter, used for converting the analog signal output by the bandpass filter into a digital signal;

[0034] The processor is used to process the digital signal output by the analog-to-digital converter and determine the result to determine the fault location of the cable.

[0035] The present invention has the following beneficial effects:

[0036] The present invention can provide an efficient fault locating method, which can quickly determine the fault position of the cable through the injection and extraction of high-frequency test signals, thereby improving the efficiency of fault handling.

[0037] Through signal processing and result judgment, the present invention can determine the fault point more accurately, reducing the repetitive work caused by inaccurate positioning; the device can perform multi-dimensional identification and detection of the cable direction, adapt to complex on-site environments and cables of different types and specifications, and improve the adaptability and accuracy of detection; compared with traditional methods, the present invention reduces the staff's dependence on experience judgment, performs signal processing and judgment through equipment, simplifies the operation process, and lowers the technical threshold; the present invention integrates signal transmission, coupling injection, signal extraction and signal processing, and is more comprehensive than existing equipment on the market, and can meet the needs of cable fault positioning in complex on-site environments; by improving the efficiency and accuracy of low-voltage cable fault positioning, the present invention helps to ensure the stable operation of the power system and reduce power outages caused by cable faults, which is of great significance to social production and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 The present invention is a block diagram of the principle of a low-voltage cable integrated positioning device in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The detailed description of the accompanying drawings is intended as an illustration of the current embodiments of the present invention and is not intended to represent the only form in which the present invention can be implemented. It should be understood that the same or equivalent functions can be accomplished by different embodiments that are intended to be included in the spirit and scope of the present invention.

[0041] See also Figure 1 , an embodiment of the present invention provides a low-voltage cable integrated positioning device, including a signal transmitting unit, an inductive coupler, a signal transmission path and a signal receiving unit;

[0042] The inductive coupler comprises a transmitting end signal injection coupler and a receiving end signal extraction coupler;

[0043] The signal transmitting unit is used to generate a high-frequency test signal injected into the cable;

[0044] The transmitting end signal injection coupler is used to inject the high-frequency test signal generated by the signal transmitting unit into the cable core in a cable bundle-to-ground coupling injection manner;

[0045] The receiving end signal extraction coupler is used to extract the high-frequency test signal coupled into the cable core;

[0046] The signal receiving unit is used to perform signal processing and result determination according to the high-frequency test signal extracted by the receiving-end signal extraction coupler to determine the fault location of the cable;

[0047] The signal transmission path is used to realize the signal transmission channel between the signal transmitting unit and the inductive coupler and between the inductive coupler and the signal receiving unit.

[0048] Specifically, the working principle of the embodiment of the present invention is as follows:

[0049] The working principle of the present invention can be divided into the following steps:

[0050] Signal transmission:

[0051] The signal transmitting unit generates a high-frequency test signal with a specific frequency and waveform so that it can be propagated in the cable and effectively detected.

[0052] Signal injection:

[0053] The signal injection coupler at the transmitting end injects the high-frequency test signal generated by the signal transmitting unit into the cable core in a cable bundle-to-ground coupling injection mode. This injection mode allows the signal to propagate along the cable core while minimizing the signal loss during the injection process.

[0054] Signal Propagation:

[0055] The injected high-frequency test signal propagates along the cable core. During the propagation process in the cable core, if there is a fault point in the cable (such as break, short circuit, etc.), the signal will produce reflection, attenuation or other forms of signal changes at the fault point.

[0056] Signal extraction:

[0057] The receiving end signal extraction coupler extracts the high-frequency test signal coupled into the cable core at the other end of the cable or at an appropriate position along the cable. The extracted signal contains the original signal propagating in the cable core and the signal changes caused by the fault point.

[0058] Signal processing and result determination:

[0059] The signal receiving unit processes the high-frequency test signal extracted by the receiving end signal extraction coupler, including steps such as amplification, filtering, and digitization, so as to analyze the characteristics of the signal.

[0060] Based on the processed signal characteristics, the signal receiving unit makes a result judgment, which involves analyzing the time domain, frequency domain and other characteristics of the signal to identify changes such as reflection and attenuation of the signal at the fault point, thereby determining the fault location of the cable.

[0061] Signal transmission path:

[0062] The signal transmission path ensures that the signal can be transmitted from the signal transmitting unit to the signal injection coupler at the transmitting end, and from the signal extraction coupler at the receiving end to the signal receiving unit, which involves physical connection methods such as cables, optical cables or wireless transmission.

[0063] Through the above steps, the embodiment of the present invention can accurately locate the low-voltage cable fault. The core of the working principle is to use the propagation characteristics of high-frequency test signals combined with signal processing technology to detect and locate the fault point in the cable. This method not only improves the efficiency and accuracy of fault detection, but also can adapt to different types of cables and complex field environments.

[0064] Furthermore, the signal transmitting unit includes:

[0065] The front-end signal simulation module is used to perform algorithm processing and control signal output according to signal requirements, thereby generating high-frequency test signals; specifically, the front-end signal simulation module is responsible for performing algorithm processing and control signal output according to signal requirements, and it generates high-frequency test signals that meet specific requirements through built-in algorithms. These algorithms can be designed based on the characteristics of the cable, the expected test results, and the needs of fault detection;

[0066] The digital-to-analog converter is connected to the front-end signal simulation module and is used to convert the digital signal into an analog high-frequency test signal; specifically, the digital-to-analog converter is connected to the front-end signal simulation module and its function is to convert the digital signal generated by the front-end signal simulation module into an analog high-frequency test signal. This step is a necessary process for digital signal processing to analog signal output.

[0067] The bandpass filter is used to perform bandpass filtering on the analog high-frequency test signal to ensure that the generated high-frequency test signal is within the frequency band of 150kHz to 15MHz; specifically, the bandpass filter is used to filter the analog high-frequency test signal to ensure that the frequency range of the output signal is between 150kHz and 15MHz. This frequency band is designed for low-voltage cable fault detection and can effectively transmit and reflect cable fault information.

[0068] An automatic gain control circuit is used to adjust the signal gain of the analog high-frequency test signal output by the bandpass filter; specifically, the automatic gain control circuit is used to adjust the gain of the analog high-frequency test signal output by the bandpass filter, so as to ensure that the signal can maintain sufficient strength during propagation, even if it encounters different cable lengths or losses, so as to facilitate detection; illustratively, the automatic gain control circuit is a negative feedback closed-loop electronic circuit, an automatic control method that automatically adjusts the gain of the amplifier circuit with the signal strength, and is divided into two parts: a gain-controlled amplifier circuit and a control voltage forming circuit, wherein the gain-controlled amplifier circuit is located in the forward amplification path, and its gain changes with the control voltage.

[0069] The differential amplifier circuit is used to differentially amplify the analog high-frequency test signal output by the automatic gain control circuit; specifically, the differential amplifier circuit differentially amplifies the analog high-frequency test signal output by the automatic gain control circuit, which can improve the quality of the signal, reduce common-mode interference, and enhance the anti-interference ability of the signal.

[0070] An adaptive impedance matching circuit is used to adjust the output impedance of the signal transmitting unit according to the change of the power line impedance, so that the end of the signal transmitting unit connected to the power line shows a constant impedance value, and the analog high-frequency test signal after differential amplification by the differential amplifier circuit is input into the transmitting end signal injection coupler after passing through the adaptive impedance matching circuit; specifically, the adaptive impedance matching circuit adjusts the output impedance of the signal transmitting unit according to the change of the power line impedance, which ensures that the end of the signal transmitting unit connected to the power line can show a constant impedance value, thereby reducing signal reflection and improving the efficiency of signal transmission. After the analog high-frequency test signal after differential amplification passes through the adaptive impedance matching circuit, it is input into the transmitting end signal injection coupler to be injected into the cable core; illustratively, the current high-frequency signal can be collected by the data acquisition module and transmitted to the calculation control module, the calculation control module calculates the current power line impedance value according to the collected data, and gives the status word of each switch, and transmits the status word to the matching module to control the on and off of the switch in the matching module, thereby selecting the size of the compensation inductance and the ratio value of the ratio transformer, so that the power line end impedance of the signal filter is maintained at a fixed resistance value.

[0071] Through the coordinated work of these sub-modules, the signal transmitting unit can generate and transmit high-frequency test signals suitable for low-voltage cable fault detection, providing a solid foundation for subsequent signal propagation, extraction and processing. This design not only improves the accuracy of fault detection, but also enhances the system's adaptability to different working environments.

[0072] Furthermore, the signal transmission path uses a metal shielding layer which is the outer layer of the insulating shield, which is used to realize the signal transmission channel, so that the signal receiving unit can sensitively sense and extract the high-frequency test signal coupled to the cable core; during the transmission process, it is affected by the difference between the high-frequency channel model and the transmission line parameters such as the conductivity, relative dielectric constant and relative magnetic permeability of the power line, and the signal variation and the relationship between the parameter change and the channel frequency response change will be detected.

[0073] Furthermore, the signal receiving unit includes:

[0074] The automatic gain control module is used to adjust the gain of the analog high-frequency test signal extracted by the receiving end signal extraction coupler to facilitate signal processing and result determination to determine the fault location of the cable; specifically, the automatic gain control module (AGC) is used to adjust the gain of the analog high-frequency test signal extracted by the receiving end signal extraction coupler. Since the signal may be attenuated due to distance and cable characteristics when propagating in the cable, the automatic gain control module can automatically adjust the signal strength to ensure that the signal maintains an appropriate level before entering the subsequent processing stage, thereby facilitating signal processing and result determination.

[0075] The bandpass filter is used to filter the high-frequency test signal output by the automatic gain control module to facilitate signal processing and result judgment to determine the fault location of the cable; specifically, the bandpass filter filters the high-frequency test signal output by the automatic gain control module to remove unnecessary frequency components and noise, ensuring that only signals within the frequency range of interest are passed to the next stage, which can improve the accuracy and efficiency of signal processing and help to more accurately determine the fault location of the cable.

[0076] The analog-to-digital converter is used to convert the analog signal output by the bandpass filter into a digital signal; specifically, the function of the analog-to-digital converter is to convert the analog signal output by the bandpass filter into a digital signal. This conversion is necessary because digital signals are easier to be processed and analyzed by a processor, and the sampling rate and resolution of the analog-to-digital converter will directly affect the accuracy of signal processing.

[0077] The processor is used to process and determine the result of the digital signal output by the analog-to-digital converter to determine the fault location of the cable; specifically, the processor is the core of the signal receiving unit, which processes and analyzes the digital signal output by the analog-to-digital converter. The processor performs the following operations:

[0078] Signal analysis: Analyze the amplitude, phase, frequency and other parameters of the signal through algorithms to identify fault characteristics in the signal;

[0079] Fault location: Calculate the specific location of the fault point based on the signal propagation time and intensity attenuation;

[0080] Result determination: Based on the analysis results, determine whether the cable has a fault, as well as the type and severity of the fault;

[0081] User Interface: The processor is also responsible for generating the user interface, displaying fault information, and providing operational feedback.

[0082] Through the coordinated work of these sub-modules, the signal receiving unit can extract useful information from the received signal and accurately determine the fault location of the cable. This design improves the automation level of fault detection, reduces human errors, and also improves the overall performance and reliability of the detection system.

[0083] The following is a specific embodiment for illustrating how the processor in the present invention processes the digital signal output by the analog-to-digital converter and determines the result to determine the fault location of the low-voltage cable:

[0084] Assume we are testing a low voltage cable with a known length of 1000 meters, which may have a fault. The implementation steps are:

[0085] Signal transmission:

[0086] The signal transmitting unit generates a high frequency test signal with a frequency of 1 MHz;

[0087] The signal is injected into the cable core through the signal injection coupler at the transmitting end;

[0088] Signal propagation and reflection:

[0089] The high-frequency test signal propagates along the cable. If there is a fault in the cable 500 meters away from the transmitter (for example, the cable is cut), the signal will be reflected at the fault point;

[0090] Signal reception and conversion:

[0091] The signal extraction coupler at the receiving end captures the reflected signal;

[0092] The analog high-frequency test signal is filtered by a bandpass filter to remove unnecessary frequency components after the gain is adjusted by the automatic gain control module;

[0093] The analog-to-digital converter (ADC) converts the filtered analog signal into a digital signal with a sampling rate of 20 MHz;

[0094] Processor processing:

[0095] Signal preprocessing: The processor performs denoising on the digital signal and uses a digital low-pass filter to remove frequency components above 1.5MHz;

[0096] Feature extraction: The processor executes the FFT algorithm to analyze the signal spectrum and finds that the 1MHz frequency component has an obvious reflection peak;

[0097] Fault location algorithm:

[0098] Wave velocity measurement: It is known that the propagation speed of the signal in the cable is about 170m / μs;

[0099] Time difference measurement: The processor measures the time difference between the transmitted signal and the reflected signal, which is 5μs;

[0100] Distance calculation: Using the formula distance = (time difference / 2)*wave speed, the distance between the fault point and the transmitter is calculated to be 425 meters;

[0101] Result judgment: The processor calculated the fault point 425 meters away from the transmitter based on the time difference and wave speed, which is 500 meters away from the actual fault location. This may be caused by the fact that the actual propagation speed of the signal in the cable is not completely consistent with the preset value.

[0102] Data output:

[0103] The processor displays the fault information on the user interface, showing "fault type: open circuit, fault location: about 425 meters";

[0104] At the same time, the processor generates a fault detection report, including the fault type, location, detection time, etc., and transmits the report to an external storage device through a USB interface.

[0105] Through this embodiment, we can see the specific application of the processor in cable fault detection and how to determine the fault location of the cable through a series of precise steps.

[0106] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A low voltage cable integrated positioning device, characterized in that: It includes a signal transmitting unit, an inductive coupler, a signal transmission path and a signal receiving unit; The inductive coupler comprises a transmitting end signal injection coupler and a receiving end signal extraction coupler; The signal transmitting unit is used to generate a high-frequency test signal injected into the cable; The transmitting end signal injection coupler is used to inject the high-frequency test signal generated by the signal transmitting unit into the cable core in a cable bundle-to-ground coupling injection manner; The receiving end signal extraction coupler is used to extract the high-frequency test signal coupled into the cable core; The signal receiving unit is used to perform signal processing and result determination according to the high-frequency test signal extracted by the receiving-end signal extraction coupler to determine the fault location of the cable; The signal transmission path is used to realize the signal transmission channel between the signal transmitting unit and the inductive coupler and between the inductive coupler and the signal receiving unit.

2. The low-voltage cable integrated positioning device according to claim 1 is characterized in that: The signal transmitting unit comprises: The front-end signal simulation module is used to perform algorithm processing and control signal output according to signal requirements, thereby generating high-frequency test signals; The digital-to-analog converter is connected to the front-end signal simulation module and is used to convert the digital signal into an analog high-frequency test signal.

3. The signal transmitting unit according to claim 2, characterized in that: The signal transmitting unit also includes: The bandpass filter is used to perform bandpass filtering on the analog high-frequency test signal to ensure that the generated high-frequency test signal is within the frequency band of 150kHz to 15MHz.

4. The signal transmitting unit according to claim 3, characterized in that: The signal transmitting unit also includes: The automatic gain control circuit is used to adjust the signal gain of the analog high-frequency test signal output by the bandpass filter.

5. The signal transmitting unit according to claim 4, characterized in that: The signal transmitting unit also includes: The differential amplifier circuit is used to differentially amplify the analog high-frequency test signal output by the automatic gain control circuit.

6. The signal transmitting unit according to claim 4, characterized in that: The signal transmitting unit also includes: The adaptive impedance matching circuit is used to adjust the output impedance of the signal transmitting unit according to the change of the power line impedance, so that the end of the signal transmitting unit connected to the power line exhibits a constant impedance value, and the analog high-frequency test signal after differential amplification by the differential amplifier circuit passes through the adaptive impedance matching circuit and is input into the transmitting end signal injection coupler.

7. The low-voltage cable integrated positioning device according to claim 1, characterized in that: The signal receiving unit comprises: The automatic gain control module is used to adjust the gain of the analog high-frequency test signal extracted by the receiving end signal extraction coupler to facilitate signal processing and result determination to determine the fault location of the cable.

8. The low-voltage cable integrated positioning device according to claim 7, characterized in that: The signal receiving unit comprises: The bandpass filter is used to filter the high-frequency test signal output by the automatic gain control module to facilitate signal processing and result determination, so as to determine the fault location of the cable.

9. The low-voltage cable integrated positioning device according to claim 8, characterized in that: The signal receiving unit comprises: An analog-to-digital converter, used for converting the analog signal output by the bandpass filter into a digital signal; The processor is used to process the digital signal output by the analog-to-digital converter and determine the result to determine the fault location of the cable.

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