Cable fault location device and method based on analog latching and vector fingerprinting

Abstract

This invention provides a cable fault location device and method based on analog latching and vector fingerprinting, belonging to the field of cable fault monitoring technology. It includes: an electromagnetic sensing module that detects electromagnetic traveling waves and generates a first trigger signal when the rate of change exceeds a threshold; an analog time latching module that responds to the first trigger signal by timing and recording information; a vector fingerprint verification module that collects vibration signals and generates a second trigger signal according to a verification criterion; and a main control and communication module that wakes up in response to the second trigger signal, reads the timing information to determine the time backtracking amount, calculates the true time difference by combining the arrival time of the sound wave, calculates the fault distance according to the corrected sound velocity, and sends the result. The beneficial effects are: by eliminating the influence of MCU wake-up delay on the time reference through analog time latching, a reliable basis for high-precision ranging is provided; by using the vector fingerprint verification criterion to distinguish radial shock waves from external interference, the false alarm rate is greatly reduced, saving energy and communication resources.

Description

Technical Field

[0001] This invention relates to the field of cable fault monitoring technology, and in particular to a cable fault location device and method based on analog latching and vector fingerprinting. Background Technology

[0002] With the increasing high-voltage and underground deployment of urban power distribution networks, the operational reliability of power cables, as a crucial carrier of power transmission, directly impacts urban power supply security. However, since cables are mostly buried underground, rapid and accurate fault location is key to ensuring quick power restoration in the event of a fault. Currently, cable fault location technology faces the following main challenges: The contradiction between low-power online monitoring and high-performance response: To achieve distributed online monitoring, fault location devices need extremely low power consumption to extend battery life or adapt to self-powered conditions. Traditional devices using simple sleep-wake mechanisms typically require milliseconds for their main control chip (MCU) to wake up from deep sleep to full-speed operation. During this process, the device loses crucial traveling wave waveform data from the initial stage of the fault. More importantly, it cannot accurately record the "arrival time of the electromagnetic wave," thus rendering time-difference-based ranging without a reference.

[0003] Environmental interference leads to frequent false alarms: The underground cable tunnel environment is complex. External vibration sources such as passing vehicles on the road and knocking during nearby construction can easily trigger simple vibration threshold sensors, causing the device to be frequently and falsely awakened. This not only consumes valuable power, but also sends a large number of invalid alarm messages to the operation and maintenance center, resulting in waste of system resources and misjudgment by operation and maintenance personnel.

[0004] Therefore, how to design a cable fault location device that can take into account nanosecond-level response, high-precision positioning, and strong anti-interference capability is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a cable fault location device based on analog latching and vector fingerprinting. The monitoring point installed on the cable includes: an electromagnetic sensing module for detecting electromagnetic traveling waves generated by a cable fault, generating a first trigger signal when the rate of change of the electromagnetic traveling wave exceeds a preset threshold; an analog time latching module connected to the electromagnetic sensing module for starting timing in response to the first trigger signal and recording timing information; a vector fingerprint verification module for waking up after the first trigger signal and acquiring the cable's vibration signal, determining whether the vibration signal is a valid shock wave signal generated by the cable fault according to a preset vector fingerprint verification criterion, and generating a second trigger signal when it is determined to be valid; and a main control and communication module connected to the analog time latching module and the vector fingerprint verification module respectively, for reading the timing information to determine a time backtracking amount in response to being woken up by the second trigger signal, obtaining the arrival time of the sound wave, calculating the true time difference of sound propagation based on the time backtracking amount and the arrival time of the sound wave, calculating the precise distance to the cable fault point based on the true time difference and the sound speed corrected by environmental parameters, and sending the location result outwards.

[0006] Preferably, the electromagnetic sensing module includes a Rogowski coil and a passive differentiating circuit, used to pick up high-frequency transient current on the cable shield and generate a pulse signal reflecting the rate of change of current.

[0007] Preferably, the analog time latch module includes a constant current source, an integrating capacitor, and a discharge circuit; the first trigger signal is used to control the constant current source to charge the integrating capacitor, and the voltage value on the integrating capacitor serves as the timing information; the discharge circuit is controlled by the main control and communication module and is used to discharge and reset the integrating capacitor after reading the timing information.

[0008] Preferably, the vector fingerprint verification module includes a triaxial accelerometer. When the radial acceleration component perpendicular to the cable surface collected by the triaxial accelerometer exceeds a first threshold, and the ratio of the radial acceleration component to the composite acceleration component parallel to the cable surface exceeds a second threshold, the vector fingerprint verification module outputs the second trigger signal.

[0009] Preferably, the main control and communication module further includes a temperature sensor for acquiring the current ambient temperature; the main control and communication module further includes a sound speed correction unit for performing nonlinear correction on the actual sound speed under the current ambient temperature based on the preset reference sound speed, reference temperature, the current ambient temperature, the first-order thermoelastic coefficient characterizing the linear effect of temperature on sound speed, and the second-order thermoelastic coefficient characterizing the nonlinear effect of temperature on sound speed in the environmental parameters, to obtain the sound speed corrected by the environmental parameters.

[0010] Preferably, the main control and communication module further includes a direction discrimination unit, which is used to perform integration calculation on the axial acceleration component and the radial acceleration component within the integration time window after the absolute moment of the fault occurrence based on the triaxial acceleration waveform collected by the vector fingerprint verification module, and to determine the upstream and downstream position of the fault point relative to the monitoring point based on the positive and negative polarity of the integration value.

[0011] Preferably, the main control and communication module further includes an approximate distance calculation unit, which is used to calculate the approximate distance from the monitoring point to the fault point by using the product of the actual time difference of acoustic propagation and the sound speed corrected by environmental parameters.

[0012] Preferably, the main control and communication module further includes a precise distance calculation unit, which is used to calculate the precise distance from the monitoring point to the fault point by using the actual time difference of sound and electromagnetic propagation and the difference between the reciprocal of the speed of sound and the speed of electromagnetic wave propagation after environmental parameter correction, through the operation relationship that distance equals time difference divided by the reciprocal of speed difference.

[0013] This invention also provides a cable fault location method based on analog latching and vector fingerprinting, applied to the aforementioned cable fault location device, comprising: Step S1, the cable fault location device detects electromagnetic traveling waves generated by a cable fault, and generates a first trigger signal when the rate of change of the electromagnetic traveling wave exceeds a preset threshold; Step S2, the cable fault location device responds to the first trigger signal, starts timing and records timing information, and simultaneously wakes up the vibration detection function; Step S3, the cable fault location device collects the vibration signal of the cable, and determines whether the vibration signal is a valid shock wave signal generated by a cable fault according to a preset vector fingerprint verification criterion, and generates a second trigger signal when it is determined to be valid; Step S4, the cable fault location device responds to the second trigger signal and wakes up the main control function; Step S5, the cable fault location device reads the timing information to determine the time backtracking amount and obtains the arrival time of the sound wave; Step S6, the cable fault location device calculates the true time difference of sound propagation based on the time backtracking amount and the arrival time of the sound wave; Step S7, the cable fault location device calculates the precise distance of the fault point based on the true time difference and the sound speed corrected by environmental parameters, and sends the location result outward.

[0014] Preferably, the method also includes a fault direction identification process, which includes performing an integral operation on the axial acceleration component and the radial acceleration component within an integral time window after the absolute moment of the fault occurrence based on the triaxial acceleration waveform collected by the vector fingerprint verification module, and determining the upstream and downstream position of the fault point relative to the monitoring point based on the positive and negative polarities of the integral value.

[0015] The above technical solution has the following advantages or beneficial effects: 1. By setting up an analog time latch module directly connected to the electromagnetic sensing module, hardware timing begins within nanoseconds of the fault occurrence. This timing information is independent of the MCU's operating state. When the MCU is awakened by subsequent vibration signals, this timing information can be read to accurately trace back to the zero moment of the electromagnetic wave's arrival, thereby eliminating the impact of the MCU wake-up delay on the time reference and providing a reliable time basis for subsequent high-precision ranging.

[0016] 2. Vibration signals are collected using a vector fingerprint verification module, and a vector fingerprint verification criterion based on the radial / axial ratio is set. This criterion can effectively distinguish between radial shock waves generated by internal cable breakdown and axial or overall displacement vibrations caused by external environmental interference (such as vehicle crushing or construction impacts), thereby greatly reducing the false alarm rate and saving system energy consumption and communication resources. Attached Figure Description

[0017] Figure 1 A schematic diagram of a cable fault location device based on analog time latching and multidimensional vector fingerprint verification is provided in a preferred embodiment of the present invention. Figure 2 This is a flowchart illustrating a cable fault location method based on analog time latching and multidimensional vector fingerprint verification, which is a preferred embodiment of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0019] In a preferred embodiment of the present invention, based on the aforementioned problems existing in the prior art, a cable fault location device based on analog time latching and multi-dimensional vector fingerprint verification is provided. The monitoring point installed on the cable includes: an electromagnetic sensing module 1, used to detect electromagnetic traveling waves generated by a cable fault, and generate a first trigger signal when the rate of change of the electromagnetic traveling wave exceeds a preset threshold; an analog time latching module 2, connected to the electromagnetic sensing module 1, used to start timing in response to the first trigger signal and record timing information; a vector fingerprint verification module 3, used to wake up after the first trigger signal and collect the vibration signal of the cable, and determine whether the vibration signal is a valid shock wave signal generated by the cable fault according to a preset vector fingerprint verification criterion, and generate a second trigger signal when it is determined to be valid; and a main control and communication module 4, connected to the analog time latching module 2 and the vector fingerprint verification module 3 respectively, used to wake up in response to the second trigger signal, read the timing information to determine the time backtracking amount, obtain the arrival time of the sound wave, calculate the true time difference of sound propagation based on the time backtracking amount and the arrival time of the sound wave, calculate the precise distance of the cable fault point based on the true time difference and the sound speed corrected by environmental parameters, and send the location result outward.

[0020] Specifically, in this embodiment, please refer to Figure 1 The device employs a four-level collaborative architecture: passive sensing, hardware latching, vector verification, and digital computation. Electromagnetic sensing module 1 captures the physical characteristics at the moment a fault occurs. When a cable experiences a breakdown fault, a steep electromagnetic traveling wave is generated at the fault point, propagating along the cable. This module senses the high-frequency transient current on the cable shield through its core components (such as a Rogowski coil and a connected passive differentiating circuit). The Rogowski coil outputs a voltage signal proportional to the rate of change of the induced current, and the subsequent passive differentiating circuit (RC high-pass filter) further extracts the high-frequency components of this signal. The module has a preset transient differentiating trigger threshold. When the rate of change of the induced current Exceeding this threshold When the comparator outputs a high-level pulse signal, it becomes the first trigger signal. This process is purely hardware-triggered, with a response time in the nanosecond range, ensuring that initial fault information is not lost.

[0021] The analog time latch module 2 is the core component for solving the wake-up latency problem. This module includes a low-power constant current source. A low-leakage integrating capacitor And a discharge circuit. In standby mode, the capacitor... The voltage at both ends is 0. When the first trigger signal is received from electromagnetic sensing module 1... At that time, the signal immediately controls the constant current source. Start by applying a constant current to the integrating capacitor Charging. At this time, the capacitor voltage... Time elapsed since the first trigger signal arrived It exhibits a strictly linear relationship:

[0022] The voltage This is called "timing information," which physically mirrors the arrival time of the electromagnetic wave. When the main control module is woken up Time passing between During this period, the main control module remains in deep sleep mode, achieving precise timing with zero power consumption.

[0023] The vector fingerprint verification module 3, in this embodiment, preferably uses an ultra-low power triaxial accelerometer (such as ADXL362). This module is awakened upon receiving the first trigger signal (or pre-configured in motion wake-up mode) and begins collecting vibration signals from the cable. The module has a pre-set "vector fingerprint verification criterion" designed to distinguish between fault impacts and environmental interference from a physical mechanism perspective. The coordinate system of the accelerometer is defined as follows: the z-axis is perpendicular to the cable surface (radial), the x-axis is parallel to the cable axis, and the y-axis is tangential. The shock wave generated by internal cable breakdown mainly diffuses radially outward; therefore, the z-axis acceleration component... The changes will be drastic. External disturbances (such as passing vehicles) typically cause axial or overall displacement. Therefore, the verification criteria for this module include two levels: First, the radial acceleration component must exceed a first threshold. ,Right now Secondly, the ratio of the radial component to the resultant acceleration component parallel to the cable surface must exceed the second threshold. ,Right now Only when both conditions are met simultaneously is the collected vibration signal determined to be a valid shock wave signal generated by a cable fault, and a second trigger signal is generated. This mechanism eliminates the vast majority of environmental false alarms from a physical perspective.

[0024] The main control and communication module 4 is the digital brain of the entire device, typically composed of an MCU and its peripheral circuitry. Upon receiving the second trigger signal from the vector fingerprint verification module, this module is awakened from deep sleep mode. Upon awakening, it immediately performs the following operations: First, it reads the voltage value of the integrating capacitor in the analog time latch module via an analog-to-digital converter (ADC). Based on the above linear relationship, the time backtracking amount from the arrival of the electromagnetic wave (i.e., the occurrence of the fault) to this moment can be accurately deduced. : ; This indicates the moment when the main control chip is woken up by a MEMS interrupt, completes initialization, and is ready to read ADC data. This is the "clock zero point" at the system software level. This indicates the absolute physical moment when the electromagnetic wave, traveling at the speed of light, arrives at the sensor after the fault occurs. At this time, the system starts hardware timing (capacitor charging), but the main control MCU has not yet woken up.

[0025] Secondly, the module retrieves the precise arrival time of the acoustic wave from the FIFO buffer of the vector fingerprint verification module. Then, the true time difference of sound and electricity propagation is calculated. This time difference is obtained by summing the software measurement time and the hardware compensation time: ; This indicates the physical moment when the mechanical shock wave (sound wave) reaches the sensor after the fault occurs.

[0026] Next, the module reads data from the onboard temperature sensor. The actual sound speed at the current temperature is calculated using a preset sound speed correction model. Finally, based on the principle of the time-of-flight acoustic method, the precise distance to the fault point was calculated. : ; After the calculation is completed, the module sends the location results and fault characteristic data to the remote operation and maintenance center through its built-in wireless communication unit (such as NB-IoT, 4G, etc.). At this point, the device has completed a full fault detection and location process.

[0027] In this embodiment, the device is also equipped with an energy harvesting unit for self-powering. This unit uses an induction coil with a high-permeability permalloy magnetic core. When the cable load current is greater than 10A, it can obtain electrical energy from the cable itself through electromagnetic induction and maintain the voltage of the supercapacitor, providing a stable and reliable power supply for the entire device.

[0028] In another preferred embodiment of the present invention, based on the foregoing embodiments, the electromagnetic sensing module 1 includes a Rogowski coil and a passive differentiating circuit for picking up high-frequency transient current on the cable shield and generating a pulse signal that reflects the rate of change of current.

[0029] Specifically, this embodiment details the electromagnetic sensing module. The Rogowski coil, due to its characteristics of no magnetic saturation, good linearity, and wide response bandwidth, is ideally suited for measuring high-frequency transient currents. When a fault traveling wave current passes through the cable shield, the voltage induced in the Rogowski coil... Rate of change of the measured current The voltage signal is then fed into a passive differentiating circuit, typically implemented as a high-pass filter using resistors and capacitors. The output of the differentiating circuit further amplifies the steep leading edge of the signal and filters out low-frequency power frequency components. When this signal exceeds the comparator's preset voltage threshold... When, the first trigger signal is output. The advantage of this embodiment is that, through the combination of Rogowski coil and differentiating circuit, a nanosecond-level response to the leading edge of the fault traveling wave is achieved, ensuring the timeliness and accuracy of the trigger signal.

[0030] In another preferred embodiment of the present invention, based on the foregoing embodiments, the analog time latch module 2 includes a constant current source, an integrating capacitor, and a discharge circuit; a first trigger signal is used to control the constant current source to charge the integrating capacitor, and the voltage value on the integrating capacitor is used as timing information; the discharge circuit is controlled by the main control and communication module and is used to discharge and reset the integrating capacitor after reading the timing information.

[0031] Specifically, this embodiment defines the specific structure and function of the analog time latch module. As mentioned before, the constant current source... and integrating capacitor This is the core of achieving linear timing. The first trigger signal acts as a charging switch, initiating the timing process. (Capacitor voltage...) As a carrier of timing information, a discharge circuit is introduced in this embodiment to prevent residual voltage on the capacitor in the event of a subsequent fault. This discharge circuit typically consists of a MOSFET switch connected in parallel with the integrating capacitor, and its control terminal is connected to the main control module. The main control module successfully reads... After completing all calculations, a control signal is sent to the discharge circuit to short-circuit the integrating capacitor, causing its voltage to return to zero, thus preparing for the next monitoring event. This ensures that each timing starts from zero, improving the system's reliability.

[0032] In another preferred embodiment of the present invention, based on the foregoing embodiments, the vector fingerprint verification module 3 includes a triaxial accelerometer. When the radial acceleration component perpendicular to the cable surface collected by the triaxial accelerometer exceeds a first threshold, and the ratio of the radial acceleration component to the composite acceleration component parallel to the cable surface exceeds a second threshold, the vector fingerprint verification module outputs a second trigger signal.

[0033] Specifically, this embodiment details the implementation of the vector fingerprint verification module. A triaxial accelerometer (MEMS accelerometer) can simultaneously acquire vibration acceleration along three orthogonal axes. This embodiment utilizes this characteristic to construct a unique "vector fingerprint" criterion. First threshold Used to filter out minute background noise, ensuring that impact events with sufficient energy occur. Second threshold. It is a dimensionless structure factor that quantifies the directionality of vibration. When an internal breakdown occurs in a cable, the impact energy is primarily released radially (z-axis), leading to... The ratio is very large. Conversely, for external disturbances, their energy is often distributed across multiple axes, especially the axial (x-axis) component, which is not negligible, resulting in a smaller ratio. By setting a reasonable... (For example, version 2.0) can ensure that only vibrations that conform to the physical characteristics of radial bursting can trigger the second trigger signal, thereby completing the physical isolation of false alarm signals at the hardware level and greatly improving the anti-interference capability of the device.

[0034] In another preferred embodiment of the present invention, based on the foregoing embodiments, the main control and communication module further includes a temperature sensor for acquiring the current ambient temperature; the main control and communication module 4 further includes a sound speed correction unit 41 for performing nonlinear correction on the actual sound speed under the current ambient temperature based on the preset reference sound speed, reference temperature, current ambient temperature, first-order thermoelastic coefficient characterizing the linear effect of temperature on sound speed, and second-order thermoelastic coefficient characterizing the nonlinear effect of temperature on sound speed in the environmental parameters to obtain the sound speed corrected by the environmental parameters.

[0035] Specifically, this embodiment introduces an environmental adaptation mechanism to improve positioning accuracy. The elastic modulus of the cable insulation layer (such as XLPE) changes with temperature, causing a change in the propagation speed of mechanical shock waves (sound waves) in the cable. Traditional fixed sound velocity models introduce significant errors. Therefore, the main control module in this embodiment incorporates a sound velocity correction unit. This unit stores a standard reference temperature. (e.g., the calibration reference speed of sound at 25°C) And the first-order thermoelastic coefficient of the material determined experimentally. and second-order thermoelastic coefficient During operation, the temperature sensor acquires the current ambient temperature in real time. The sound speed correction unit calculates the current actual sound speed based on the following nonlinear correction model: ; This model enables the device to adaptively adjust the sound velocity value under different seasons and operating conditions, thereby ensuring high accuracy in distance calculation across the entire temperature range.

[0036] In another preferred embodiment of the present invention, based on the foregoing embodiments, the main control and communication module 4 further includes a direction discrimination unit 42, which is used to perform integration calculation on the axial acceleration component and the radial acceleration component within the integration time window after the absolute moment of the fault occurrence based on the triaxial acceleration waveform collected by the vector fingerprint verification module, and to determine the upstream and downstream position of the fault point relative to the monitoring point based on the positive and negative polarity of the integration value.

[0037] Specifically, this embodiment provides a fault direction identification function, which is particularly important for monitoring points installed at branch nodes or long lines. When a shock wave (sound wave) propagates through a sensor, the direction of particle vibration is related to the direction of wave propagation. The direction determination unit utilizes this characteristic. It first determines the absolute moment of fault occurrence. (The starting point for the integration time used to calculate the fault direction is usually the moment when the shock wave energy just breaks through the noise floor.) Then, within a shorter time window... Within (e.g., 2-5 milliseconds, to avoid interference from reflected waves), the axial acceleration... and radial acceleration Integrate the product of the products and take the sign: ; Since the installation coordinate system is fixed, when a fault occurs on the left or right side of the sensor, the axial acceleration... The initial polarity will be opposite, thus causing the integral value to... The symbols are different. Therefore, through The sign of the fault can be used to determine whether the fault source is located upstream or downstream of the device, providing more accurate location guidance for maintenance personnel.

[0038] In another preferred embodiment of the present invention, based on the foregoing embodiments, the main control and communication module 4 further includes an approximate distance calculation unit 43, which is used to calculate the approximate distance from the monitoring point to the fault point by using the product of the real time difference of sound and electricity propagation and the sound speed after environmental parameter correction.

[0039] Specifically, this embodiment provides a simplified distance calculation method. This takes into account the propagation speed of electromagnetic waves. Extremely fast (close to the speed of light), its propagation time is much shorter than that of sound waves and can be ignored in most engineering applications. Traditional formulas neglect system wake-up time; this solution utilizes... Compensation will be provided.

[0040] set up: : The moment when the MCU wakes up and begins processing (the current system clock is at zero).

[0041] The actual arrival time of electromagnetic waves (at Before).

[0042] The arrival time of the sound wave.

[0043] As can be seen from the analog integrator circuit, the arrival time of the electromagnetic wave is relative to... Time backtracking for:

[0044] Therefore, the true time difference of sound and electricity propagation for:

[0045] Note: Here This is the arrival time of the sound wave as measured after the MCU wakes up. Sound waves are usually slow and will arrive after the MCU has woken up.

[0046] Therefore, the approximate distance calculation unit 43 directly and quickly calculates the fault distance. The following calculation formula is used (an approximate formula, considering that the speed of electromagnetic wave propagation is much greater than the speed of sound, and assuming that the propagation time of electromagnetic wave is 0):

[0047] This method requires little computation and has a fast processing speed, making it suitable for scenarios with high real-time requirements or less stringent accuracy requirements.

[0048] In another preferred embodiment of the present invention, based on the foregoing embodiments, the main control and communication module 4 further includes a precise distance calculation unit 44, which is used to calculate the precise distance from the monitoring point to the fault point by using the real time difference of sound and electricity propagation and the difference between the reciprocal of the speed of sound and the speed of electromagnetic wave propagation after environmental parameter correction, through the operation relationship that distance is equal to time difference divided by the reciprocal of speed difference.

[0049] Specifically, this embodiment provides a more precise distance calculation method, suitable for scenarios with extremely high positioning accuracy requirements. This method also takes into account the finite propagation time of electromagnetic waves. Let the absolute moment of the fault occurrence be... The speed of electromagnetic wave propagation is The speed of sound wave propagation is (i.e., the aforementioned corrected speed of sound) Then we have: ; ; in, and These represent the absolute times when the electromagnetic wave and the sound wave arrive at the sensor, and their true time difference, respectively. Solve the two equations simultaneously to eliminate the remaining equations. This allows us to determine the precise fault distance: ; The precise distance calculation unit 44 uses this formula for calculation. Because... Much larger The result is very close to the approximate calculation result, but it can provide a more accurate correction in long-distance fault location.

[0050] Another preferred embodiment of the present invention provides a cable fault location method based on analog time latching and multidimensional vector fingerprint verification, which is applied to the cable fault location device of any of the foregoing embodiments. Please refer to... Figure 2 The method includes: Step S1, the cable fault location device detects the electromagnetic traveling wave generated by the cable fault, and generates a first trigger signal when the rate of change of the electromagnetic traveling wave exceeds a preset threshold; Step S2, the cable fault location device responds to the first trigger signal, starts timing and records timing information, and simultaneously wakes up the vibration detection function; Step S3, the cable fault location device collects the vibration signal of the cable, and determines whether the vibration signal is a valid shock wave signal generated by the cable fault according to a preset vector fingerprint verification criterion, and generates a second trigger signal when it is determined to be valid; Step S4, the cable fault location device responds to the second trigger signal and wakes up the main control function; Step S5, the cable fault location device reads the timing information to determine the time backtracking amount and obtains the arrival time of the sound wave; Step S6, the cable fault location device calculates the true time difference of sound propagation based on the time backtracking amount and the arrival time of the sound wave; Step S7, the cable fault location device calculates the precise distance of the fault point based on the true time difference and the sound speed corrected by environmental parameters, and sends the location result outward.

[0051] The method in this embodiment, through hardware-level event triggering and time latching, combined with intelligent wake-up and verification based on vector fingerprints, and further supplemented by accurate calculation of environmental parameters, fully realizes the entire process from fault occurrence to location information reporting, and has the advantages of fast response, low power consumption, anti-interference and high accuracy.

[0052] In another preferred embodiment of the present invention, based on the aforementioned method embodiment, a fault direction identification process is further included, which includes performing an integration operation on the axial acceleration component and the radial acceleration component within an integration time window after the absolute moment of the fault occurrence based on the triaxial acceleration waveform collected by the vector fingerprint verification module, and determining the upstream and downstream position of the fault point relative to the monitoring point based on the positive and negative polarities of the integration value.

[0053] Specifically, this embodiment adds a direction determination function to the existing positioning distance. By performing the integral calculation described in the aforementioned direction determination unit, it is possible to determine which side of the monitoring point the fault point is located on. This is crucial for troubleshooting multi-branch cable networks or long-distance lines, providing maintenance personnel with a clearer addressing direction and significantly improving fault location efficiency.

[0054] To more clearly illustrate the feasibility and effectiveness of the technical solution of this invention in practical applications, a specific engineering example will be used as an example below.

[0055] In another preferred embodiment of the present invention, a fault monitoring terminal for 10kV distribution cable joints is provided. This embodiment is based on the device of any of the foregoing embodiments, and through specific hardware selection and parameter settings, demonstrates the complete workflow of the device from fault occurrence to location information reporting.

[0056] Specifically, this embodiment monitors a section of 10kV distribution cable. The device is installed at the intermediate joint of the cable, using either an internal or external mounting method to ensure tight coupling with the cable body.

[0057] 1. Hardware Circuit and Parameter Design Energy Harvesting Unit: To enable long-term operation without an external power source, the device includes an energy harvesting unit. This unit employs an induction coil with a high-permeability permalloy magnetic core. When the cable load current exceeds 10A, it can harvest electrical energy from the cable itself through electromagnetic induction and store it in a supercapacitor, providing power for the entire device.

[0058] Electromagnetic sensing module: As mentioned above, it includes a Rogowski coil and a passive differentiating circuit for capturing fault traveling waves.

[0059] Analog Time Latch Module: To achieve accurate timing with low power consumption, this embodiment uses a polypropylene film capacitor with extremely low leakage current as the integrating capacitor. Its capacitance is 10nF. Constant current source. The current is set to According to the formula If the wake-up time of the main control module (MCU) is 2ms, the capacitor voltage will be charged to This voltage is within the optimal range for ADC sampling, ensuring the accuracy of the time backtracking reading.

[0060] Vector fingerprint verification module: Utilizes an ultra-low power triaxial accelerometer (such as the ADXL362). Configure it in Link Mode and preset hardware criteria: only when the z-axis (radial) acceleration exceeds 10g (i.e., ... An interrupt is triggered and a second trigger signal is output only when the impact signal (value = 10g) lasts for less than 5ms (which meets the characteristics of cable breakdown impact). This setting filters out most long-lasting environmental vibrations at the hardware level.

[0061] 2. Specific Work Process S1, Fault Occurrence: Assume an insulation breakdown fault occurs in the cable body 120 meters from the monitoring point. The electromagnetic traveling wave generated by the fault travels at approximately... Propagating along the cable at a speed of m / s, approximately Then they arrived at the monitoring point.

[0062] S2, Hardware Lock-in and Timing: The differentiating circuit of the device's electromagnetic sensing module detected... The mutation occurs, generating the first trigger signal. This signal immediately activates the constant current source of the analog time latch module to the integrating capacitor. Charging begins, and the timer starts. Simultaneously, this signal also powers the vector fingerprint verification module, putting it into standby mode.

[0063] S3, Vibration propagation: The mechanical shock wave (sound wave) generated by the fault propagates at approximately... Propagation in the cable medium at a speed of m / s is expected Then they arrived at the monitoring point.

[0064] S4, Vibration Verification and Wake-up: Approximately 60ms later, the shock wave reaches the monitoring point. The triaxial accelerometer of the vector fingerprint verification module detects severe radial (z-axis) vibration with a peak value exceeding 10g and a duration consistent with the preset shock characteristics, thus satisfying the vector fingerprint verification criteria. The module then pulls the interrupt pin high, generating a second trigger signal to wake the main control module (MCU) from deep sleep.

[0065] S5, MCU Processing and Data Reading: After the MCU is woken up, perform the following operations: The voltage value of the integrating capacitor in the analog time latch module is read using an ADC. At this point, the capacitor has been charged for approximately 60ms (Note: If the capacitor is at full capacity, a segmented counting system or a larger capacitor is required; here, we assume the capacity is sufficient).

[0066] By tracing back and precisely capturing the peak value of the acoustic waveform from the FIFO buffer of the vector fingerprint verification module, the exact moment of arrival of the acoustic wave can be determined. .

[0067] Read data from the onboard temperature sensor to obtain the current ambient temperature. .

[0068] S6 Environmental Parameter Correction and Distance Calculation: Assuming the current ambient temperature is read as The sound velocity correction unit of the main control module calculates the actual sound velocity using a nonlinear correction model. Assume the reference temperature T0 = 25°C. CT0=25 C, reference speed of sound m / s, first-order thermoelastic coefficient Second-order thermoelastic coefficient Neglecting this, the corrected speed of sound is: m / s.

[0069] Calculate the true time difference of sound and electricity propagation In this example, since the MCU is only awakened after the shock wave arrives, the arrival time of the sound wave is... It happens within a very short time after the MCU wakes up. (Actual time difference) This is the time backtracking amount calculated in step S5. This is approximately equal to the propagation time of the shock wave, which is 60ms.

[0070] Calculate the distance to the fault: .

[0071] S7 Result Reporting: The main control module will report the calculated fault distance (e.g., The system encapsulates information such as the fault location (meters), fault direction (if applicable), and fault timestamp, and sends it to the remote maintenance center via the built-in NB-IoT wireless communication module. The maintenance team can then quickly locate the fault point based on this information.

[0072] S8 System Reset: After communication is completed, the main control module controls the discharge circuit to reset the integrating capacitor of the analog time latch module. The voltage on the device is released to zero, preparing for the next monitoring event. The system then re-enters ultra-low power standby mode.

[0073] Through the above specific embodiments, it is clear that the device and method proposed in this invention can effectively cope with complex working conditions in actual engineering. By simulating time latch hardware, the MCU wake-up delay problem is solved; by using vector fingerprint verification, environmental interference is eliminated from a physical mechanism perspective; and by combining a sound velocity model corrected for environmental parameters, high-precision and high-reliability accurate location of cable faults is finally achieved under self-powered conditions.

[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A cable fault location device based on analog latching and vector fingerprinting, installed at a monitoring point on a cable, characterized by, The application relates to a cable fault location system. The electromagnetic sensing module is used for detecting an electromagnetic traveling wave generated by a cable fault, and a first trigger signal is generated when a change rate of the electromagnetic traveling wave exceeds a preset threshold value. The analog time latch module is connected with the electromagnetic sensing module, and is used for starting timing and recording timing information in response to the first trigger signal.

2. A cable fault location apparatus according to claim 1, characterised in that, The vector fingerprint verification module is used for waking up and collecting a vibration signal of the cable after the first trigger signal, judging whether the vibration signal is an effective shock wave signal generated by the cable fault according to a preset vector fingerprint verification criterion, and generating a second trigger signal when the vibration signal is judged to be effective.

3. The cable fault location apparatus of claim 1, wherein, The main control and communication module is connected with the analog time latch module and the vector fingerprint verification module, and is used for reading the timing information to determine a time backtracking amount, acquiring a sound wave arrival time, calculating a real time difference of sound and electricity propagation according to the time backtracking amount and the sound wave arrival time, calculating an accurate distance of a fault point of the cable according to the real time difference and a sound speed modified by an environment parameter, and sending a positioning result outward.

4. The cable fault location apparatus of claim 1, wherein, The electromagnetic sensing module comprises a Rogowski coil and a passive differential circuit, and is used for picking up high-frequency transient current on a shielding layer of the cable and generating a pulse signal reflecting a current change rate.

5. The cable fault location apparatus of claim 1 wherein, The analog time latch module comprises a constant current source, an integration capacitor and a discharge circuit.

6. The cable fault location apparatus of claim 1, wherein, The vector fingerprint verification module comprises a three-axis accelerometer.

7. The cable fault location apparatus of claim 1 wherein, The main control and communication module further comprises a temperature sensor used for acquiring a current environment temperature, and a sound speed correction unit used for nonlinearly correcting an actual sound speed under the current environment temperature to obtain the sound speed modified by the environment parameter based on a preset reference sound speed, a reference temperature, the current environment temperature, a first-order thermoelastic coefficient representing a linear influence of temperature on the sound speed and a second-order thermoelastic coefficient representing a nonlinear influence of temperature on the sound speed. The main control and communication module further comprises a direction discrimination unit used for performing integral operation on axial acceleration components and radial acceleration components in an integral time window after an absolute time of fault occurrence according to three-axis acceleration waveforms collected by the vector fingerprint verification module, and judging upstream and downstream positions of the fault point relative to a monitoring point according to polarities of the integral values. The main control and communication module further comprises an approximate distance calculation unit used for calculating an approximate distance from the monitoring point to the fault point by using a product of the real time difference of sound and electricity propagation and the sound speed modified by the environment parameter.

8. The cable fault location apparatus of claim 1 wherein, The main control and communication module also includes a precise distance calculation unit, which uses the actual time difference of sound and electricity propagation and the difference between the reciprocal of the speed of sound and the speed of electromagnetic wave propagation after environmental parameter correction, to calculate the precise distance from the monitoring point to the fault point through the operation relationship that distance equals the time difference divided by the reciprocal of the speed difference.

9. A method for cable fault location based on analog latching and vector fingerprinting, characterized in that, The cable fault location device according to any one of claims 1-8 comprises: step S1, the cable fault location device detects electromagnetic traveling waves generated by a cable fault, and generates a first trigger signal when the rate of change of the electromagnetic traveling wave exceeds a preset threshold; step S2, the cable fault location device responds to the first trigger signal, starts timing and records timing information, and simultaneously wakes up the vibration detection function; step S3, the cable fault location device collects the vibration signal of the cable, and determines whether the vibration signal is a valid shock wave signal generated by the cable fault according to a preset vector fingerprint verification criterion, and generates a second trigger signal when it is determined to be valid; step S4, the cable fault location device responds to the second trigger signal and wakes up the main control function; step S5, the cable fault location device reads the timing information to determine the time backtracking amount and obtains the arrival time of the sound wave; step S6, the cable fault location device calculates the true time difference of sound and electricity propagation based on the time backtracking amount and the arrival time of the sound wave; step S7, the cable fault location device calculates the precise distance of the fault point based on the true time difference and the sound speed corrected by environmental parameters, and sends the location result outward.

10. The cable fault location method of claim 9, wherein, It also includes a fault direction identification process, which involves integrating the axial acceleration component and the radial acceleration component within the integration time window after the shock wave starts, based on the triaxial acceleration waveform collected by the vector fingerprint verification module, and determining the upstream and downstream position of the fault point relative to the monitoring point based on the positive and negative polarities of the integral value.

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