Operation state fault monitoring method, system and device for heavy-load overhead line

Abstract

The invention discloses an operation state fault monitoring method, system and device for a heavy-load overhead line, and relates to the technical field of electrical fault detection of the heavy-load overhead line. The method comprises the following steps: injecting a high-frequency test signal into a heavy-load overhead line to carry out predefined fault detection so as to obtain a total harmonic distortion rate; performing first harmonic optimization adjustment according to comparative analysis of the total harmonic distortion rate and a threshold value; performing harmonic second optimization adjustment according to the monitoring analysis result of the external load fluctuation of the heavy-load overhead line; and performing harmonic third optimization adjustment according to the monitoring analysis result of the external environment fluctuation of the heavy-load overhead line. According to the invention, through multi-stage distribution adjustment, the effect of improving the dynamic regulation and control accuracy of the high-frequency test signal injection fault monitoring method of the heavy-load overhead line in extreme weather is achieved; the problem of insufficient dynamic regulation and control accuracy of a high-frequency test signal injection fault monitoring method of a heavy-load overhead line in extreme weather exists.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical fault detection for large-load overhead lines, and particularly to an operating state fault monitoring method, system and device for large-load overhead lines. Background Art

[0002] With the development of society and the acceleration of the urbanization process, the demand for electricity is increasing continuously. As an important part of power transmission, the safe and stable operation of large-load overhead lines is crucial for ensuring power supply. Therefore, real-time monitoring and fault early warning of large-load overhead lines have become an important topic in the power industry, especially for the monitoring of the problems of high-resistance grounding anomalies and harmonic interference anomalies occurring simultaneously in large-load overhead lines under extreme weather conditions.

[0003] The existing operating state fault monitoring methods for large-load overhead lines are realized through the following methods: automatically injecting high-frequency pulse signals within a specific frequency range, adopting efficient signal coupling technology, and using anti-interference technologies such as pseudo-random coding, orthogonal coding, and spread spectrum technology, so as to analyze the fault location through the impedance parameters and resonance parameters obtained by spectrum analysis, and complete the electrical fault monitoring of large-load overhead lines.

[0004] For example, a method and system for on-line monitoring and fault early warning positioning of overhead lines disclosed in the invention patent with the publication number of: CN119165296A includes: collecting traveling wave signals by sensors installed at each measurement point of the overhead line; identifying the traveling wave signals and fault types of faults by using deep learning algorithms; using traveling wave ranging technology and GIS to obtain the distances of each fault point relative to the measurement point, matching the geographical information and topological structure of the overhead line, and obtaining the preliminary positions of each fault point; using virtual simulation software to inject faults and simulate the generation of traveling wave signals separately at the preliminary positions of each fault point corresponding to each traveling wave signal of each fault; for each traveling wave signal of each fault, comparing its similarity with the corresponding simulated traveling wave signal, and determining the final fault position of the fault point according to the similarity result and generating a fault early warning positioning prompt.

[0005] For example, a diagnostic device for early warning and positioning of overhead cable faults in transmission lines disclosed in the invention patent with the publication number of: CN119375615A, which relates to the technical field of cable fault detection, includes a detection data acquisition unit, a partial discharge detection unit and a fault detection and processing unit. By optimizing the sensors through a sensor optimization module and assisting the signals through a signal assistance module, the electromagnetic interference during cable detection can be reduced after processing, so as to stably obtain traveling wave signals, and through signal amplification and signal filtering technologies, the signals can be enhanced and the signal-to-noise ratio can be improved.

[0006] However, in the process of implementing the technical solution of the invention in the embodiments of the present application, it is found that the above technology has at least the following technical problems:

[0007] In the prior art, in extreme weather, high-resistance grounding anomalies and large harmonic interference may occur simultaneously in large-load overhead lines. By automatically injecting high-frequency pulse signals within a specific frequency range and analyzing the impedance parameters and resonance parameters obtained through spectrum analysis to analyze the fault location, there are external environmental impacts and external large-load impacts. The resulting signal phase jitter makes it difficult to analyze the problem of positioning and early warning, and there is a problem of insufficient dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines in extreme weather. Summary of the Invention

[0008] The embodiments of the present application provide a method, system, and device for monitoring the operating state faults of large-load overhead lines, which solve the problem of insufficient dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines in the prior art, and achieve the effect of improving the dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines in extreme weather.

[0009] The embodiments of the present application provide a method for monitoring the operating state faults of large-load overhead lines, including the following steps: injecting high-frequency test signals into the large-load overhead lines for predefined fault detection to obtain the total harmonic distortion rate; comparing and analyzing the total harmonic distortion rate with a threshold to perform the first harmonic optimization adjustment; after the first harmonic optimization adjustment, monitoring and analyzing the external load fluctuations of the large-load overhead lines, and performing the second harmonic optimization adjustment according to the monitoring and analysis results of the external load fluctuations of the large-load overhead lines; after the second harmonic optimization adjustment, monitoring and analyzing the external environmental fluctuations of the large-load overhead lines, and performing the third harmonic optimization adjustment according to the monitoring and analysis results of the external environmental fluctuations of the large-load overhead lines.

[0010] Further, the injecting high-frequency test signals into the large-load overhead lines for predefined fault detection specifically includes: using a high-frequency test signal generator to generate pulse signals with specific frequencies, coupling and injecting the high-frequency test signals into the large-load overhead lines through a capacitive coupler; installing high-frequency sensors at the receiving monitoring points to capture reflected signals and transmitted signals; and positioning impedance anomaly points and resonance anomaly points through spectrum analysis extraction and traveling wave positioning algorithms.

[0011] Further, the predefined fault detection by injecting a high-frequency test signal into a large-load overhead line further includes: sampling and collecting at the sampling rate built in a broadband current transformer downstream of the injection point or at the line end to obtain a high-frequency time-domain signal; processing the high-frequency time-domain signal through a fast Fourier transform to obtain a frequency-domain complex spectrum; extracting the fundamental wave amplitude of the frequency-domain complex spectrum from a large-load overhead line operation state fault database. If the frequency-domain amplitude value of the frequency-domain complex spectrum is greater than a predefined proportional value of the fundamental wave amplitude, no adjustment is made; if the frequency-domain amplitude value of the frequency-domain complex spectrum is less than or equal to the predefined proportional value of the fundamental wave amplitude, the part of the frequency-domain complex spectrum where the frequency-domain complex spectrum is less than the predefined proportional value of the corresponding fundamental wave amplitude is filtered; and analyzing and extracting the total harmonic distortion rate of the large-load overhead line from the frequency-domain complex spectrum.

[0012] Further, the first optimization adjustment of the harmonics specifically includes: if the total harmonic distortion rate of the large-load overhead line is less than the total harmonic distortion rate threshold, no adjustment is made; if the total harmonic distortion rate of the large-load overhead line is equal to or greater than the total harmonic distortion rate threshold, the passive filter is tuned to start the passive filter at a predefined position for harmonic suppression.

[0013] Further, after the first optimization adjustment of the harmonics, the external load fluctuation monitoring and analysis of the large-load overhead line is carried out, specifically including: directly extracting from the large-load overhead line database the historical average value of the load power of the large-load overhead line, the historical average value of the leakage current of the large-load overhead line, and the average value of the discharge intensity of partial discharge; detecting the maximum value of the load power of the large-load overhead line and the minimum value of the load power of the large-load overhead line through the intelligent monitoring terminal of the large-load overhead line; detecting the maximum value of the leakage current of the large-load overhead line through the corresponding leakage current acquisition loop; detecting the maximum value of the discharge intensity of partial discharge of the large-load overhead line through the corresponding high-frequency partial discharge detector; analyzing the ratio of the difference between the maximum value and the minimum value of the load power of the large-load overhead line to the historical average value of the load power of the large-load overhead line, and then correcting it with the weight factor of the humidity on the load power to obtain the first negative influence component of the external load fluctuation of the large-load overhead line; performing exponential correction on the ratio of the maximum value of the leakage current of the large-load overhead line to the historical average value of the leakage current of the large-load overhead line to obtain the first ratio value, and performing multiple joint analysis on the ratio of the maximum value of the discharge intensity of partial discharge of the large-load overhead line to the average value of the discharge intensity of partial discharge of the large-load overhead line and the number of discharge times of the discharge intensity of partial discharge of the large-load overhead line to obtain the second ratio value, adding the first ratio value and the second ratio value, and then correcting it with the weight factor of the humidity on the partial and leakage discharges to obtain the second negative influence component of the external load fluctuation of the large-load overhead line; comprehensively analyzing the first negative influence component of the external load fluctuation of the large-load overhead line and the second negative influence component of the external load fluctuation of the large-load overhead line to obtain the negative influence value of the external load fluctuation of the large-load overhead line.

[0014] Further, the second optimization adjustment of the harmonics is carried out according to the monitoring and analysis results of the external load fluctuation of the large-load overhead line, specifically including: if the negative influence value of the external load fluctuation of the large-load overhead line is less than the negative threshold of the external load fluctuation of the large-load overhead line, no second optimization adjustment of the harmonics is carried out; if the negative influence value of the external load fluctuation of the large-load overhead line is equal to or greater than the negative threshold of the external load fluctuation of the large-load overhead line, the second optimization adjustment of the harmonics is carried out, specifically: subtracting the negative threshold of the external load fluctuation of the large-load overhead line from the negative influence value of the external load fluctuation of the large-load overhead line to obtain the negative difference value of the external load fluctuation of the large-load overhead line; according to the negative difference value of the external load fluctuation of the large-load overhead line and the predefined matching rule of the negative difference value of the load fluctuation, reducing the period window of the fast Fourier transform and increasing the overlap rate of the fast Fourier transform.

[0015] Further, after the second optimization adjustment of the harmonics, the external environment fluctuation monitoring and analysis of the large-load overhead line are carried out, specifically including: collecting the maximum mechanical stress of the conductor and the maximum swing amplitude of the conductor corresponding to the large-load overhead line through a fiber Bragg grating sensor; if the maximum mechanical stress or the maximum swing amplitude of the conductor is greater than or equal to the corresponding threshold, the hydraulic tension adjustment device is started; if the maximum mechanical stress or the maximum swing amplitude of the conductor is less than the corresponding threshold, no adjustment is made, and the standard value of the wire mechanical stress, the standard value of the conductor swing amplitude, and the capacitance threshold of the large-load overhead line are directly extracted from the large-load overhead line database. The maximum capacitance and the minimum capacitance of the large-load overhead line are collected through a distributed capacitance sensor. The ratio of the maximum mechanical stress of the conductor to the standard value of the wire mechanical stress is corrected with the wire mechanical stress weighting factor to obtain the first negative component of the external environment of the large-load overhead line. The ratio of the maximum swing amplitude of the conductor to the standard value of the conductor swing amplitude is corrected with the conductor swing amplitude weighting factor to obtain the second negative component of the external environment of the large-load overhead line. The difference analysis between the maximum capacitance and the minimum capacitance of the large-load overhead line, the ratio analysis with the capacitance threshold of the large-load overhead line, and the correction with the large-load overhead line capacitance weighting factor are carried out to obtain the third negative component of the external environment of the large-load overhead line. By combining the negative influence value of the external load fluctuation of the large-load overhead line, the first negative component of the external environment of the large-load overhead line, the second negative component of the external environment of the large-load overhead line, and the third negative component of the external environment of the large-load overhead line, the negative influence value of the external environment of the large-load overhead line is obtained. The negative influence value of the external environment of the large-load overhead line is used to represent the quantification level of the negative influence of the negative influence value of the external load fluctuation of the large-load overhead line, the first negative component of the external environment of the large-load overhead line, the second negative component of the external environment of the large-load overhead line, and the third negative component of the external environment of the large-load overhead line on the degree of influence of the large-load overhead line by the external load fluctuation.

[0016] Further, the third optimization adjustment of the harmonics is carried out according to the monitoring and analysis results of the external environment fluctuation of the large-load overhead line, specifically including: if the negative influence value of the external environment of the large-load overhead line is less than the negative influence threshold of the external environment of the large-load overhead line, no adjustment is made; if the negative influence value of the external environment of the large-load overhead line is equal to or greater than the negative influence threshold of the external environment of the large-load overhead line, the large-load overhead line at the corresponding injection point is subjected to spread spectrum gain through a predefined broadband coupler and nonlinear notch filtering is performed on the predefined frequency.

[0017] An embodiment of the present application provides an operating state fault monitoring system for a large-load overhead line, including a predefined fault detection module, a first harmonic optimization adjustment module, a second harmonic optimization adjustment module, and a third harmonic optimization adjustment module; the predefined fault detection module is configured to perform predefined fault detection on the large-load overhead line by injecting a high-frequency test signal to obtain the total harmonic distortion rate; the first harmonic optimization adjustment module is configured to perform the first harmonic optimization adjustment based on the comparison and analysis of the total harmonic distortion rate and a threshold; the second harmonic optimization adjustment module is configured to monitor and analyze the external load fluctuation of the large-load overhead line after the first harmonic optimization adjustment, and perform the second harmonic optimization adjustment according to the monitoring and analysis result of the external load fluctuation of the large-load overhead line; the third harmonic optimization adjustment module is configured to monitor and analyze the external environment fluctuation of the large-load overhead line after the second harmonic optimization adjustment, and perform the third harmonic optimization adjustment according to the monitoring and analysis result of the external environment fluctuation of the large-load overhead line.

[0018] An embodiment of the present application provides a device applying the operating state fault monitoring method for a large-load overhead line as described above, including a hydraulic cylinder of a hydraulic tension adjustment device, a hydraulic pump station of the hydraulic tension adjustment device, a control valve group of the hydraulic tension adjustment device, a sensing module of the hydraulic tension adjustment device, a control module of the hydraulic tension adjustment device, a communication module of the hydraulic tension adjustment device, and a protective housing of the hydraulic tension adjustment device: the hydraulic cylinder of the hydraulic tension adjustment device: is configured to change the effective length of the wire through the telescopic movement of the piston rod; the hydraulic pump station of the hydraulic tension adjustment device: is configured to provide a high-pressure oil source to drive the hydraulic cylinder to act; the control valve group of the hydraulic tension adjustment device: is configured to control the flow rate and direction of the hydraulic oil; the sensing module of the hydraulic tension adjustment device: is configured to detect and feedback through a fiber Bragg grating sensor; the control module of the hydraulic tension adjustment device: is configured to receive the sensor signal by an embedded controller and output an adjustment instruction according to PID control; the communication module of the hydraulic tension adjustment device: is configured to be linked with the operating state fault monitoring system of the large-load overhead line and support remote instruction and status feedback; the protective housing of the hydraulic tension adjustment device: is configured to be corrosion-resistant, rain-proof, and dust-proof, and adopts an IP67 protection level.

[0019] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0020] 1. By comparing and analyzing the total harmonic distortion rate with the threshold, the first harmonic optimization adjustment is carried out; the second harmonic optimization adjustment is carried out according to the monitoring and analysis results of the external load fluctuation of the large-load overhead line; the third harmonic optimization adjustment is carried out according to the monitoring and analysis results of the external environment fluctuation of the large-load overhead line, achieving the effect of improving the dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines under extreme weather, and solving the problem of insufficient dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines in the prior art under extreme weather.

[0021] 2. According to the monitoring and analysis results of the external load fluctuation of the large-load overhead line, the second harmonic optimization adjustment is carried out. By dynamically adjusting the FFT window and the overlap rate, the real-time resolution balance, anti-interference enhancement and resource efficiency optimization are realized, and thus the fault monitoring reliability of the large-load line under extreme weather is significantly improved.

[0022] 3. According to the monitoring and analysis results of the external environment fluctuation of the large-load overhead line, the third harmonic optimization adjustment is carried out. Through high-precision sensing, dynamic weight correction, nonlinear interference suppression and spread spectrum gain optimization, the accurate monitoring and active regulation of the large-load overhead line under extreme weather are realized. By suppressing the low-frequency modulation noise through the Volterra model, the signal-to-noise ratio is significantly improved; the wire tension is adjusted by the hydraulic device in seconds, and the swing amplitude is greatly reduced; thus providing key technical support for the construction of smart grids, especially showing significant engineering value in extreme scenarios such as typhoons and icing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of the method for monitoring the operating state fault of the large-load overhead line provided by the embodiment of the present application;

[0024] Figure 2 It is a schematic structural diagram of the system for monitoring the operating state fault of the large-load overhead line provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] By providing a method, system and device for monitoring the operating state fault of a large-load overhead line, the embodiment of the present application solves the problem of insufficient dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines in the prior art, and achieves the effect of improving the dynamic regulation accuracy of the high-frequency test signal injection monitoring fault method for large-load overhead lines under extreme weather.

[0026] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0027] Such as Figure 1As shown in the figure, it is a flowchart of a method for monitoring the operating state faults of a large-load overhead line provided by an embodiment of the present application. This method is applied to a system for monitoring the operating state faults of a large-load overhead line, and the method includes the following steps: injecting a high-frequency test signal into the large-load overhead line for predefined fault detection to obtain the total harmonic distortion rate; performing a first harmonic optimization adjustment based on the comparison and analysis of the total harmonic distortion rate and a threshold; after the first harmonic optimization adjustment, monitoring and analyzing the external load fluctuations of the large-load overhead line, and performing a second harmonic optimization adjustment based on the results of the monitoring and analysis of the external load fluctuations of the large-load overhead line; after the second harmonic optimization adjustment, monitoring and analyzing the external environmental fluctuations of the large-load overhead line, and performing a third harmonic optimization adjustment based on the results of the monitoring and analysis of the external environmental fluctuations of the large-load overhead line.

[0028] In this embodiment, in extreme weather such as typhoons, the strong winds of the typhoon cause branches to break and hang on the wire, forming a high-resistance grounding. When the wire is overloaded, the joule heat carbonizes the branches, and the grounding resistance gradually decreases, eventually triggering an arc discharge; the typhoon is accompanied by heavy rain, causing the wire to swing violently, resulting in periodic overloading of the wire and accelerating sensor drift; the instantaneous reduction of the wire spacing causes flashover, and at the same time, the high-humidity environment exacerbates partial discharge. For the above scenarios, generally, a capacitive coupler is used to automatically inject a specific high-frequency pulse signal, and then the corresponding impedance abnormal points and resonance abnormal points are analyzed through the spectral analysis of the influence of the high-frequency pulse signal on the large-load overhead line to obtain the corresponding operating state fault points of the large-load overhead line. However, because the external influences on the large-load overhead line are complex and diverse, the above method is prone to misjudgment, and the accuracy needs to be improved.

[0029] Furthermore, injecting a high-frequency test signal into the large-load overhead line for predefined fault detection specifically includes: using a high-frequency test signal generator to generate a pulse signal with a specific frequency, and coupling and injecting the high-frequency test signal into the large-load overhead line through a capacitive coupler; installing a high-frequency sensor at the receiving monitoring point to capture the reflected signal and the transmitted signal; and locating the impedance abnormal points and resonance abnormal points through spectral analysis extraction and traveling wave location algorithms.

[0030] In this embodiment, a high-frequency test signal generator is used to generate a pulsed signal with a specific frequency, usually ranging from 10 kHz to 1 MHz. The specific frequency should avoid the power frequency (50 / 60 Hz) and its harmonics and adapt to the line impedance characteristics. The signal waveform often selects short-time pulses (such as square waves or sine wave envelopes) to enhance the anti-interference ability and reflection feature recognition. The coupler uses the principle of capacitive voltage division to couple the high-frequency test signal to the high-voltage wire while isolating the power-frequency high voltage to ensure the safety of the equipment. The injected high-frequency test signal propagates along the wire. When encountering impedance discontinuities (such as tree branch short circuits, wire breaks, flashover points), reflected waves and transmitted waves are generated. The reflected wave returns to the injection point, and the transmitted wave continues to propagate towards the end of the line. By means of spectrum analysis, time-domain reflectometry (TDR) or traveling wave location algorithms, the signal attenuation, phase change, and resonance characteristics are analyzed to locate impedance anomaly points (such as carbonized tree branches) or resonance points (such as capacitance changes caused by reduced wire spacing).

[0031] It is connected to the line through a high-voltage capacitor (i.e., a capacitive coupler), and the low-voltage side is connected to the signal generator. The common parameters are from 1000 pF to 0.1 μF, and the withstand voltage level needs to match the line voltage (such as 110 kV and above).

[0032] The choke can be installed on the substation side to prevent the high-frequency test signal from entering the substation equipment and ensure that the signal propagates along the line.

[0033] A high-frequency sensor can be used to receive the reflected signal, usually a broadband current transformer or voltage transformer.

[0034] The injection position is usually selected at the substation outgoing line end or the tower at the end of the line to facilitate signal coverage of the entire line.

[0035] The relative position of the receiving monitoring point to the injection point is the receiving position distance, with a typical range of 10 km to 50 km.

[0036] By means of spectrum analysis and traveling wave location algorithms, impedance anomaly points and resonance anomaly points are located, specifically including: the high-frequency sensor captures the frequency-domain data of the reflected and transmitted signals. In a typhoon environment, multiple samplings can be superimposed and averaged to suppress rainstorm noise (such as random pulses caused by raindrop collisions).

[0037] Spectrum feature extraction: The time-domain signal is converted into the frequency domain through fast Fourier transform, and the amplitude spectrum and phase spectrum are extracted.

[0038] For example, in the case of carbonized tree branches, the resonance frequency shifts due to the reduction of the grounding resistance. When the wire spacing is reduced, the capacitance increases and the resonance frequency decreases.

[0039] If an abnormal resonance peak appears at a certain section of the line, calculate the increase in capacitance at this point based on the line parameters, and infer that the conductor spacing has decreased (such as caused by conductor swing and collision due to strong typhoon winds). The determination of the abnormal resonance peak is based on setting a threshold value. There is a corresponding set threshold range at a specific frequency spectrum position. Any value exceeding or not reaching the set threshold range is determined as an abnormal resonance peak.

[0040] Calculate the increase in capacitance at this point based on the line parameters, and infer that the conductor spacing has decreased. The specific steps are exemplified as follows:

[0041] Establish an equivalent circuit model of the line: The transmission line can be simplified into a distributed parameter model, which includes inductance, capacitance, resistance, and conductance. The characteristic impedance and propagation constant of the line are the key parameters describing its electrical characteristics:

[0042] Characteristic impedance: It is determined by the ratio of inductance and capacitance, and reflects the resistance of the line to current.

[0043] Propagation constant: It describes the attenuation and phase change of the signal when propagating on the line. In the case of neglecting losses, the propagation constant is mainly determined by inductance and capacitance.

[0044] Resonant frequency: The resonant frequency of the line is inversely proportional to the square root of the product of inductance and capacitance, and inversely proportional to the line length.

[0045] Assuming that the inductance per unit length, capacitance, and line length of the line are known, the fundamental resonant frequency of the line can be calculated. The fundamental resonant frequency is the lowest resonant frequency of the line under normal conditions and is usually used to determine whether the line is in a normal working state.

[0046] Setting the threshold of the abnormal resonance peak: To determine whether the resonant frequency is abnormal, a permitted frequency deviation range needs to be set. This range is usually obtained based on historical data or theoretical calculations. If the detected resonant frequency exceeds this range (either too high or too low), it is determined as abnormal.

[0047] Derivation of the relationship between capacitance change and resonant frequency: When the conductor spacing decreases and the capacitance increases, the resonant frequency will change. The resonant frequency is inversely proportional to the square root of the capacitance. Therefore, the change in capacitance can be deduced from the detected resonant frequency offset. Specifically, if the detected resonant frequency is lower than the normal value, it indicates that the capacitance has increased; conversely, if the resonant frequency is higher than the normal value, it indicates that the capacitance has decreased.

[0048] Inverse Deduction of Capacitance Model with Changing Conductor Spacing: The capacitance between conductors is inversely proportional to the conductor spacing. Based on the change in capacitance, the change in conductor spacing can be deduced. The specific steps include: establishing a relationship model between capacitance and spacing according to the capacitance and conductor spacing in the normal state; calculating the new conductor spacing using the detected capacitance change; comparing the new conductor spacing with the safety spacing to determine if there is any abnormality.

[0049] Traveling Wave Location Algorithm

[0050] Principle: Utilize the time difference of the traveling wave generated at the fault point reaching both ends of the line, and combine with GPS synchronization to achieve double - end location.

[0051] Specific Steps:

[0052] Sensors at both ends of the line are synchronized by GPS clock (error ≤ 1μs) to record the arrival time T 1 (starting end) and T 2 (ending end).

[0053] Location Calculation:

[0054] S represents the fault location.

[0055] S Z represents the total length of the heavy - load overhead line.

[0056] V represents the signal propagation speed. The typical value for an overhead line is 98% of the speed of light, approximately 294000 km / s.

[0057] T 1 represents the arrival time of the traveling wave at the starting end. T 2 represents the arrival time of the traveling wave at the ending end.

[0058] Waveform Recognition and Anti - interference:

[0059] Extract the singular points (such as the sudden rising edge) of the traveling wave head through wavelet transform to distinguish the fault traveling wave from noise.

[0060] Example: The time difference T 2 -T 1 of the fault traveling wave detected at both ends is 0.4 ms, and the total length of the heavy - load overhead line is 120 km. Calculate that the fault point is 60.2 km from the starting end, and notify the relevant personnel to confirm that the flashover is caused by the reduction of the conductor spacing at this place.

[0061] Further, for predefined fault detection by injecting a high-frequency test signal into a large-load overhead line, it further includes: sampling and collecting through the sampling rate built in a broadband current transformer downstream of the injection point or at the line end to obtain a high-frequency time-domain signal; processing the high-frequency time-domain signal through a fast Fourier transform to obtain a frequency-domain complex spectrum; extracting the fundamental wave amplitude of the frequency-domain complex spectrum from the large-load overhead line operation state fault database. If the frequency-domain amplitude value of the frequency-domain complex spectrum is greater than the predefined proportional value of the fundamental wave amplitude, no adjustment is made; if the frequency-domain amplitude value of the frequency-domain complex spectrum is less than or equal to the predefined proportional value of the fundamental wave amplitude, then filter the part of the frequency-domain complex spectrum where the frequency-domain complex spectrum is less than the predefined proportional value of the corresponding fundamental wave amplitude; extract and analyze the total harmonic distortion rate of the large-load overhead line based on the frequency-domain complex spectrum.

[0062] In this embodiment, the sampling rate of the broadband current transformer (such as a Rogowski coil, with a bandwidth of DC–30 MHz) is ≥10 MS / s (assuming the fundamental wave of the large-load overhead line is 1 MHz, then the corresponding sampling rate is 100 MS / s to ensure capturing at least 10 harmonics), and the recording duration: at least includes 10 fundamental wave periods (such as recording 1 ms when the fundamental wave is 10 kHz). Trigger mode: Use the synchronous trigger signal of the signal transmitter to avoid random noise interference. Anti-aliasing filtering: Add a low-pass filter (cutoff frequency = signal highest harmonic frequency × 1.5) before the ADC. DC offset removal: Example: If the injected signal is a 1-MHz sine wave, it is necessary to collect at least 10 μs (10 periods) of the time-domain waveform, and the sampling rate is set to 100 MS / s, corresponding to 100 sampling points per period.

[0063] Execute the FFT to convert the time-domain signal into a frequency-domain complex spectrum, and determine the fundamental wave frequency at the frequency point with the largest amplitude in the frequency-domain complex spectrum (such as 1 MHz). Example: If the amplitude of the spectrum after FFT is 10 V (fundamental wave) at 1 MHz, 0.5 V (second harmonic) at 2 MHz, and 0.3 V (third harmonic) at 3 MHz, the amplitude threshold of the frequency-domain complex spectrum (such as 1% of the fundamental wave amplitude), and the harmonics below the threshold are regarded as noise. Amplitude threshold filtering, set the frequency points with amplitudes lower than 1% of the fundamental wave amplitude in the frequency-domain complex spectrum to zero (regarded as noise), and retain the effective harmonic components.

[0064] The main steps for extracting and analyzing the total harmonic distortion rate based on the frequency-domain complex spectrum are exemplified as follows:

[0065] Identify the fundamental frequency (usually the power frequency of 50 / 60 Hz) from the frequency-domain complex spectrum, and extract the amplitude corresponding to the fundamental frequency; extract the corresponding amplitudes at integer multiples of the fundamental frequency (such as the 2nd, 3rd to Nth harmonics), and calculate using the formula for total harmonic distortion rate. Before calculation, filtering is required through an amplitude threshold filter (such as 1%-5% of the fundamental amplitude) to avoid interference from invalid frequency points. Example process: If the fundamental amplitude of a certain signal is 100 V, the 2nd harmonic is 30 V, and the 3rd harmonic is 20 V, then the THD calculation is as follows: This result indicates that the harmonic component accounts for 36.06% of the total signal.

[0066] Furthermore, for the first optimization adjustment of harmonics, specifically including: if the total harmonic distortion rate of the large-load overhead line is less than the total harmonic distortion rate threshold, no adjustment is made; if the total harmonic distortion rate of the large-load overhead line is equal to or greater than the total harmonic distortion rate threshold, the passive filter is tuned to start the passive filter at a predefined position for harmonic suppression.

[0067] In this embodiment, for the passive filter tuning: adjust the resonant frequency of the LC passive filter to match the current dominant harmonics (such as the 3rd and 5th). Example: If the resonant peak is detected at 150 kHz (the capacitance increases due to the reduction of the wire spacing), adjust the filter parameters to 150 kHz. Principle of passive filtering: Utilize the series resonance characteristic of LC to present a low-impedance path at specific frequencies (such as the 3rd and 5th harmonics), and bypass the harmonic current to the ground.

[0068] After suppressing the harmonics, reduce the interference of noise on the positioning of impedance abnormal points (such as carbonized branches) to avoid misjudgment. Example: The raindrop noise during typhoon and heavy rain may cause the THD to be falsely high, and after filtering, the positioning error can be reduced from ±500 m to ±50 m. Suppressing harmonics can reduce the risk of wire overheating (Joule heat is positively correlated with harmonic loss), avoid accelerating the carbonization of branches and grounding faults. Avoid resonance overvoltage from causing flashover or insulation breakdown.

[0069] In terms of software and hardware, the hardware includes LC filters, sensors, and tuning components; the software involves harmonic analysis tools, parameter calculation software, and monitoring systems.

[0070] The predefined position is generally set to start the LC filter bank near the dominant harmonic source (such as the low-voltage side of the transformer or the concentrated point of nonlinear loads), and adopt a star or delta wiring method. For example, for the 5th harmonic, a single-tuned filter parallel structure is adopted.

[0071] Real-time monitor the total harmonic distortion rate (THD) through a power quality monitoring device (such as a PowerQualityAnalyzer) to ensure that the THD is reduced below the threshold (for example, from 15% to 5%).

[0072] The LC passive filter bank (including adjustable reactors, capacitors, and switching switches) is used to absorb specific harmonic frequencies.

[0073] Harmonic analyzers (such as Fluke 435II) and traveling wave location devices (such as SEL-T400L) are used to achieve harmonic detection and fault location.

[0074] Furthermore, after the first optimization adjustment of harmonics, external load fluctuation monitoring and analysis of large-load overhead lines are carried out, specifically including: directly extracting the historical average value of the load power of the large-load overhead line, the historical average value of the leakage current of the large-load overhead line, and the average discharge intensity of partial discharges from the large-load overhead line database; detecting the maximum load power of the large-load overhead line and the minimum load power of the large-load overhead line through the intelligent monitoring terminal of the large-load overhead line; detecting the maximum leakage current of the large-load overhead line through the corresponding leakage current acquisition loop; detecting the maximum discharge intensity of partial discharges of the large-load overhead line through the corresponding high-frequency partial discharge detector; analyzing the ratio of the difference between the maximum load power of the large-load overhead line and the minimum load power of the large-load overhead line to the historical average value of the load power of the large-load overhead line, and then correcting it with the weight factor of humidity on the load power to obtain the first negative influence component of the external load fluctuation of the large-load overhead line; performing exponential correction on the ratio of the maximum leakage current of the large-load overhead line to the historical average value of the leakage current of the large-load overhead line to obtain the first ratio value, and jointly analyzing the ratio of the maximum discharge intensity of partial discharges of the large-load overhead line to the average discharge intensity of partial discharges of the large-load overhead line with the number of discharges of the discharge intensity of partial discharges of the large-load overhead line to obtain the second ratio value, superimposing the first ratio value and the second ratio value, and then correcting it with the weight factor of humidity on partial and leakage discharges to obtain the second negative influence component of the external load fluctuation of the large-load overhead line; comprehensively analyzing the first negative influence component of the external load fluctuation of the large-load overhead line and the second negative influence component of the external load fluctuation of the large-load overhead line to obtain the negative influence value of the external load fluctuation of the large-load overhead line.

[0075] In this embodiment, FZ 0 represents the number of segments of the large-load overhead line, FZ 0 = 1, 2, 3,..., FZ, where FZ represents the total number of segments of the large-load overhead line, JK 0 represents the inspection and monitoring points of the large-load overhead line, JK 0 = 1, 2, 3,..., JK, where JK represents the total number of inspection and monitoring points of the large-load overhead line, JS 0 represents the detection time period of the large-load overhead line, JS 0 = 1, 2, 3,..., JS, where JS represents the total number of detection time periods of the large-load overhead line.

[0076] Indicates the JKth 0 of the JKth inspection and monitoring point on the large load overhead line in the FZth section 0 of the JSth 0 Negative impact value of external load fluctuation of the large load overhead line in the JSth section of the detection time period. The negative impact value of external load fluctuation of the large load overhead line is used to quantify the relative negative distortion degree value of the comprehensive impact caused by external load fluctuation on the large load overhead line.

[0077]

[0078] Indicates the JKth 0 of the JKth inspection and monitoring point on the large load overhead line in the FZth section 0 of the JSth 0 Maximum load power of the large load overhead line in the JSth section of the detection time period. The intelligent monitoring terminal of the large load overhead line collects the line load current in real time through a high-precision current transformer and calculates the power parameters using the FFT algorithm. For example, it supports minute-level data collection and can monitor the maximum load power. Its built-in wireless communication module (such as 4G / 5G) can upload the data to the master station system to achieve real-time tracking and collection of load peaks.

[0079] Indicates the JKth 0 of the JKth inspection and monitoring point on the large load overhead line in the FZth section 0 of the JSth 0 Minimum load power of the large load overhead line in the JSth section of the detection time period.

[0080] Indicates the JKth 0 of the JKth inspection and monitoring point on the large load overhead line in the FZth section 0 of the JSth 0 Historical average value of the load power of the large load overhead line in the JSth section of the detection time period. The historical average value of the load power of the large load overhead line is directly extracted from the large load overhead line database and is used to represent the average level in the historical data of the load power of the large load overhead line.

[0081] Indicates the JKth 0 of the JKth inspection and monitoring point on the large load overhead line in the FZth section 0 of the JSth 0 Maximum value of the leakage current of the large load overhead line in the JSth section of the detection time period. In the corresponding leakage current acquisition loop at the inspection and monitoring point for the large load overhead line monitoring, it can be installed on the top of the insulator string to directly couple the leakage current signal and achieve real-time acquisition of the maximum value of the leakage current of the large load overhead line.

[0082] Indicates the JKth 0 of the FZth section of the high-load overhead line 0 and the JSth 0 historical average leakage current of the high-load overhead line during the detection time period, which is directly extracted from the high-load overhead line database.

[0083] Indicates the JKth 0 of the FZth section of the high-load overhead line 0 and the JSth 0 maximum discharge intensity of partial discharge of the high-load overhead line during the detection time period, which is captured in real time by a high-frequency partial discharge detector (such as OMICRON MPD600).

[0084] Indicates the JKth 0 of the FZth section of the high-load overhead line 0 and the JSth 0 average discharge intensity of partial discharge of the high-load overhead line during the detection time period, which is directly extracted from the high-load overhead line database.

[0085] Indicates the JKth 0 of the FZth section of the high-load overhead line 0 and the JSth 0 number of discharges of the discharge intensity of partial discharge of the high-load overhead line during the detection time period.

[0086] High humidity (>90%) reduces the surface resistance of the insulator, increases the leakage current (from 1 mA to 10 mA), and at the same time accelerates the generation of broadband interference by partial discharge. The influence of humidity on the high-load overhead line is mainly reflected in two aspects: high humidity (>90%) causes the surface resistance of the insulator to decrease, the leakage current to increase (from 1 mA to 10 mA), resulting in additional load power loss and increased load power fluctuation. Humidity accelerates the enhancement of the conductivity of the contaminated layer, forms a conductive channel, and causes the discharge pulse frequency and amplitude to increase (such as the number of discharge pulses per minute is greater than 100).

[0087] Indicates the JKth 0 of the FZth section of the high-load overhead line 0 and the JSth 0 weight factor of humidity on the load power during the detection time period, which reflects the influence degree of the additional loss of leakage current caused by humidity on the line load capacity.

[0088] Indicating the JK 0 th inspection and monitoring point of the FZ 0 th large-load overhead line segment 0 The weight factor of humidity on partial and leakage discharges during the JSth detection time period, reflecting the enhancement effect of humidity on the discharge intensity (such as the number of pulses, amplitude).

[0089] Simulate different humidity conditions in an artificial climate chamber, measure the leakage current and discharge pulse characteristics, and fit the coefficients. Through calibration with a non-linear model and measured data, dynamic weight allocation can be achieved, constructing a mapping relationship between the real-time humidity, the weight factor of humidity on load power, and the weight factor of humidity on partial discharge. Input the actual humidity to obtain the corresponding weight factor of humidity on load power and the weight factor of humidity on partial discharge.

[0090] The specific weight factor construction process example is as follows: Set a humidity gradient of 20%-95% (interval 10%) in the artificial climate chamber, and keep the temperature constant at 30°C to simulate the large-load line environment. Use high-precision sensors to continuously monitor the leakage current, partial discharge pulses, and load power at each humidity for 2 hours, and synchronously record the environmental humidity data. Extract effective electrical parameters through wavelet denoising and pulse integration algorithms.

[0091] Fit 10 groups of experimental data into a continuous function, generate a humidity-weight mapping table with 512 discrete points, and embed it in the FPGA chip to achieve μs-level query. When the real-time humidity is input, use cubic spline interpolation to dynamically calculate the weight value.

[0092] Furthermore, according to the monitoring and analysis results of the external load fluctuation of the large-load overhead line, perform the second harmonic optimization adjustment, specifically including: If the negative impact value of the external load fluctuation of the large-load overhead line is less than the negative threshold of the external load fluctuation of the large-load overhead line, then do not perform the second harmonic optimization adjustment; If the negative impact value of the external load fluctuation of the large-load overhead line is equal to or greater than the negative threshold of the external load fluctuation of the large-load overhead line, then perform the second harmonic optimization adjustment, specifically: Subtract the negative threshold of the external load fluctuation of the large-load overhead line from the negative impact value of the external load fluctuation of the large-load overhead line to obtain the negative difference of the external load fluctuation of the large-load overhead line; According to the negative difference of the external load fluctuation of the large-load overhead line and the predefined negative difference matching rule of load fluctuation, reduce the period window of the fast Fourier transform and increase the overlap rate of the fast Fourier transform.

[0093] In this embodiment, the predefined negative difference matching rule of load fluctuation is the corresponding relationship between the negative difference of the external load fluctuation of the large-load overhead line and the adjustment of reducing the period window of the specific fast Fourier transform and increasing the overlap rate of the fast Fourier transform;

[0094] For example, when the negative difference of the external load fluctuation of the large-load overhead line is 0.5, FFT analysis with 10 fundamental wave periods (such as a 200 ms window corresponding to 50 Hz) is used to improve the frequency resolution to 0.5 Hz.

[0095] Python code example: window_length = 10(1 / 50).

[0096] That is 0.2 seconds (10 cycles).

[0097] When the negative difference of the external load fluctuation of the large-load overhead line is 2, a fluctuation period (5-cycle window) is adopted: when the load suddenly changes, the window is shortened to 5 cycles (100 ms), sacrificing the resolution to improve the real-time performance and suppressing the spectral tailing effect.

[0098] When the negative difference of the external load fluctuation of the large-load overhead line is 0.5, a 30% overlap rate is adopted (such as a window length of 200 ms and a 60 ms slide each time), and the truncation error is reduced by weighting with a Hanning window.

[0099] When the negative difference of the external load fluctuation of the large-load overhead line is 2, a 50% overlap rate is adopted (such as a window length of 200 ms and a 10 ms slide each time), and the truncation error is reduced by weighting with a Hanning window.

[0100] Furthermore, after the second harmonic optimization adjustment, the external environment fluctuation monitoring and analysis of the large-load overhead line are carried out, specifically including:

[0101] Collecting the maximum mechanical stress of the corresponding conductor and the maximum conductor swing amplitude of the large-load overhead line through a fiber Bragg grating sensor;

[0102] If the maximum mechanical stress or the maximum conductor swing amplitude is greater than or equal to the corresponding threshold value, the hydraulic tension adjustment device is started;

[0103] If the maximum mechanical stress or the maximum wire swing amplitude is less than the corresponding threshold value, no adjustment is made. The standard values of wire mechanical stress, wire swing amplitude, and the capacitance threshold of the high-load overhead line are directly extracted from the high-load overhead line database. The maximum capacitance and the minimum capacitance of the high-load overhead line are collected by a distributed capacitance sensor. The ratio of the maximum wire mechanical stress to the standard value of wire mechanical stress is corrected with the wire mechanical stress weight factor to obtain the first negative component of the external environment of the high-load overhead line. The ratio of the maximum wire swing amplitude to the standard value of wire swing amplitude is corrected with the wire swing amplitude weight factor to obtain the second negative component of the external environment of the high-load overhead line. The difference between the maximum capacitance and the minimum capacitance of the high-load overhead line is analyzed, and the ratio analysis with the capacitance threshold of the high-load overhead line is corrected with the capacitance weight factor of the high-load overhead line to obtain the third negative component of the external environment of the high-load overhead line. By combining the negative influence value of the external load fluctuation of the high-load overhead line, the first negative component of the external environment of the high-load overhead line, the second negative component of the external environment of the high-load overhead line, and the third negative component of the external environment of the high-load overhead line for analysis, the negative influence value of the external environment of the high-load overhead line is obtained. The negative influence value of the external environment of the high-load overhead line is used to represent the quantification level of the negative influence of the external load fluctuation of the high-load overhead line, the first negative component of the external environment of the high-load overhead line, the second negative component of the external environment of the high-load overhead line, and the third negative component of the external environment of the high-load overhead line on the degree of influence of the high-load overhead line by the external load fluctuation.

[0104] In this embodiment, the maximum wire mechanical stress and wire swing amplitude of the high-load overhead line are collected by a fiber Bragg grating sensor. The fiber Bragg grating sensor is a periodic refractive index modulation structure inscribed in the optical fiber. When the optical fiber is subjected to strain or temperature changes, the grating period changes, resulting in a shift in the center wavelength of the reflected light. By demodulating the wavelength shift, the wire strain and vibration frequency can be inversely deduced, and then the swing amplitude can be calculated.

[0105] When the fiber Bragg grating sensor detects that the mechanical stress or wire swing amplitude of the high-load overhead line exceeds the set threshold value, the following comprehensive measures can be taken to suppress the wire swing and mechanical stress problems under typhoon weather: If the stress exceeds the threshold value (such as 80% of the design value), start the hydraulic tension adjustment device to control the wire tension within the safe range (such as ±5% of the design tension).

[0106] Working principle and process example of the hydraulic tension adjustment device:

[0107] If the mechanical stress or swing amplitude is greater than the corresponding threshold value, a regulation instruction is triggered. Tension control objectives: Suppress swing: Increase the wire rigidity by increasing the tension (shortening the equivalent wire length) to reduce the swing amplitude. Reduce stress: Avoid material overload by reducing the tension (lengthening the equivalent wire length). Hydraulic action process: Drive the hydraulic cylinder to extend and retract to change the position of the wire suspension point (for example, shortening by 1 cm can increase the tension by about 35%). Through the feedback closed-loop verification of the tension sensor until the actual tension enters the safe range (such as ±5% of the design value).

[0108] Indicates the JKth 0 of the FZth section of the large load overhead line 0 and the JSth 0 negative impact value of the external environment of the large load overhead line during the detection time period. The negative impact value of the external environment of the large load overhead line is used to quantify the relative negative distortion degree value of the comprehensive impact caused by the external environment fluctuation on the large load overhead line.

[0109]

[0110] Indicates the JKth 0 of the FZth section of the large load overhead line 0 and the JSth 0 maximum value of the wire mechanical stress during the detection time period of the large load overhead line.

[0111] Indicates the JKth 0 of the FZth section of the large load overhead line 0 and the JSth 0 standard value of the wire mechanical stress during the detection time period of the large load overhead line. The standard value of the wire mechanical stress is directly extracted from the large load overhead line database and is used to represent the average level in the historical data of the wire mechanical stress of the large load overhead line.

[0112] Indicates the JKth 0 of the FZth section of the large load overhead line 0 and the JSth 0 maximum value of the wire swing amplitude during the detection time period of the large load overhead line. An inclination sensor is installed on the wire to measure the inclination angle of the wire. Combining the wire length and inclination data, the maximum value of the wire swing amplitude is calculated.

[0113] Indicates the JKth 0 of the FZth section of the large load overhead line 0 and the JSth 0The standard value of the wire swing amplitude in the segment detection time period is directly extracted from the large load overhead line database.

[0114] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the maximum value of the capacitance of the large load overhead line in the JS 0 th segment detection time period is captured in real time by a distributed capacitance sensor.

[0115] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the minimum value of the capacitance of the large load overhead line in the JS 0 th segment detection time period.

[0116] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the capacitance threshold of the large load overhead line in the JS 0 th segment detection time period is directly extracted from the large load overhead line database.

[0117] The coupled influence of wind force values on wire mechanical stress, swing amplitude, and line capacitance needs to be quantified by a dynamic weight factor.

[0118] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the wire mechanical stress weight factor in the JS 0 th segment detection time period, which reflects the direct influence of wind force on wire tension and tower load and is positively correlated with the square of the wind speed.

[0119] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the wire swing amplitude weight factor in the JS 0 th segment detection time period, which characterizes the inertial coupling effect of wind force on the wire and is affected by wind speed, wind direction, and the natural frequency of the wire.

[0120] Indicates the JK 0 th inspection and monitoring point of the FZ 0 th large load overhead line segment, and the large load overhead line capacitance weight factor in the JS 0 th segment detection time period, which quantifies the dynamic influence of wind-induced wire spacing changes on capacitance parameters and has a linear relationship with the reciprocal of the wire spacing.

[0121] Simulate different wind force conditions in an artificial climate chamber. Through calibration with a non-linear model and measured data, dynamic weight allocation can be achieved, and a mapping relationship between the real-time wind force value and the weight factors of the conductor mechanical stress, the conductor swing amplitude, and the capacitance of the large-load overhead line can be constructed. Input the actual wind force value to obtain the corresponding weight factors of the conductor mechanical stress, the conductor swing amplitude, and the capacitance of the large-load overhead line.

[0122] A specific example of the weight factor construction process is as follows: Set multiple wind speeds (3 - 20 m / s), different wind directions (0°, 45°, 90°), and turbulence intensities (10% - 50%) in the artificial climate chamber to simulate the dynamic response of the conductor under extreme wind conditions. Real-time monitor the dynamic tension fluctuation of the conductor through a high-precision tension sensor. Use an inertial unit (IMU) to collect the three-dimensional swing trajectory of the conductor and extract the maximum amplitude and main frequency.

[0123] Based on the aerodynamic load formula and the turbulence correction term, establish a tension - wind speed - wind direction mapping relationship. Swing dynamics model: Solve the frequency-domain response characteristics of the amplitude and wind speed through the swing equation to map the corresponding weight factors. Compile the training model into FPGA-executable code to achieve microsecond-level weight query (resolution 0.5 m / s, 5° wind direction). Generate a wind speed - weight mapping table to support bilinear interpolation for dynamic correction.

[0124] Furthermore, perform the third harmonic optimization adjustment according to the monitoring and analysis results of the external environment fluctuation of the large-load overhead line. Specifically, if the negative impact value of the external environment of the large-load overhead line is less than the negative impact threshold of the external environment of the large-load overhead line, no adjustment is made; if the negative impact value of the external environment of the large-load overhead line is equal to or greater than the negative impact threshold of the external environment of the large-load overhead line, then perform spread-spectrum gain on the large-load overhead line at the corresponding injection point through a predefined broadband coupler and perform non-linear notch filtering on the predefined frequency.

[0125] In this embodiment, the coupling device: Install a broadband coupler (compatible with the installation position of the leakage current monitoring loop) on the top of the insulator string to support signal injection / extraction in the 1 kHz - 30 MHz frequency band.

[0126] The matching network can be pre-adjusted according to the actual conductor differences to make the signal reflection loss ≤ 20 dB.

[0127] For example, if the negative impact value of the external environment of the high-load overhead line is equal to or greater than the negative impact threshold of the external environment of the high-load overhead line, the spread spectrum bandwidth will be expanded from the baseband of 10 kHz to 1 MHz, reducing the interference power density by more than 20 dB. The coupling degree between the signal frequency band and the harmonic energy directly affects the signal-to-noise ratio. By hopping frequencies to avoid the interference area and combining spread spectrum to disperse energy, the suppression effect of narrowband harmonics on specific frequency points can be suppressed.

[0128] Example steps for implementing nonlinear notch filtering:

[0129] Obtain the wire swing acceleration signal through a fiber grating sensor, with a sampling rate ≥ 100 Hz (meeting the Nyquist theorem for capturing 2 Hz interference). Modulation frequency estimation: Perform a fast Fourier analysis on the wire swing acceleration signal to extract the dominant modulation frequency and its harmonics.

[0130] Band-pass filtering: Use an FIR filter (such as designed with a Hamming window) to extract the signal in the 0.52 Hz frequency band and suppress high-frequency noise. Use the preprocessed wire swing acceleration signal as the input and the interfered line signal as the output to construct a training data set.

[0131] Model the nonlinear system through the Volterra series to describe the coupling relationship between mechanical vibration and electrical signal interference. Volterra kernel identification: Use the acceleration signal as the input and adaptively identify the high-order kernel parameters through the LMS algorithm to optimize the nonlinear interference prediction model. The LMS (Least Mean Squares) algorithm is an adaptive filtering algorithm, also called the minimum mean square error algorithm, which is widely used in fields such as signal processing, system identification, and noise cancellation. Its core idea is to iteratively adjust the filter coefficients to minimize the mean square error (MSE) between the output of the filter and the desired signal. Dynamic notch design: Construct a multi-stage notch filter bank, design the transfer function for the modulation harmonics, and superimpose the Volterra nonlinear correction term to cancel the interference. Use a sliding window (such as a 5-second data block) to update the kernel parameters in real time to adapt to the frequency drift caused by changes in wind speed. Dynamically adjust the nonlinear order according to the wind speed (such as enabling a 3rd-order kernel when the wind speed ≥ 15 m / s) to enhance the ability to suppress nonlinear interference. Evaluate the filtering effect through the signal-to-noise ratio (SNR) and verify the fault location error. When the error exceeds the threshold, trigger parameter retraining. The Volterra series can accurately capture the nonlinear interaction between wire swing and electrical signals through high-order kernels (such as 2nd-order and 3rd-order), which cannot be achieved by traditional linear filters.

[0132] Such as Figure 2As shown in the figure, it is the structure diagram of the operation status fault monitoring system for large-load overhead lines provided by the embodiments of the present application. The operation status fault monitoring system for large-load overhead lines provided by the embodiments of the present application includes a predefined fault detection module, a first harmonic optimization adjustment module, a second harmonic optimization adjustment module, and a third harmonic optimization adjustment module; the predefined fault detection module is used to inject a high-frequency test signal into the large-load overhead line for predefined fault detection to obtain the total harmonic distortion rate; the first harmonic optimization adjustment module is used to perform the first harmonic optimization adjustment according to the comparison and analysis of the total harmonic distortion rate and the threshold; the second harmonic optimization adjustment module is used to monitor and analyze the external load fluctuation of the large-load overhead line after the first harmonic optimization adjustment, and perform the second harmonic optimization adjustment according to the monitoring and analysis result of the external load fluctuation of the large-load overhead line; the third harmonic optimization adjustment module is used to monitor and analyze the external environment fluctuation of the large-load overhead line after the second harmonic optimization adjustment, and perform the third harmonic optimization adjustment according to the monitoring and analysis result of the external environment fluctuation of the large-load overhead line.

[0133] The operation status fault monitoring device for large-load overhead lines provided by the embodiments of the present application includes: a hydraulic cylinder of the hydraulic tension adjustment device, a hydraulic pump station of the hydraulic tension adjustment device, a control valve group of the hydraulic tension adjustment device, a sensing module of the hydraulic tension adjustment device, a control module of the hydraulic tension adjustment device, a communication module of the hydraulic tension adjustment device, and a protective housing of the hydraulic tension adjustment device: the hydraulic cylinder of the hydraulic tension adjustment device: is used to change the effective length of the wire through the telescopic movement of the piston rod; the hydraulic pump station of the hydraulic tension adjustment device: is used to provide a high-pressure oil source to drive the hydraulic cylinder to act; the control valve group of the hydraulic tension adjustment device: is used to control the flow rate and direction of the hydraulic oil; the sensing module of the hydraulic tension adjustment device: is used to detect and feedback through a fiber Bragg grating sensor; the control module of the hydraulic tension adjustment device: is used for the embedded controller to receive the sensor signal and output an adjustment instruction according to PID control; the communication module of the hydraulic tension adjustment device: is used to be linked with the operation status fault monitoring system of the large-load overhead line and support the remote instruction and status feedback; the protective housing of the hydraulic tension adjustment device: is used for corrosion resistance, rain and dust protection, and adopts the IP67 protection level.

[0134] In this embodiment, the hydraulic actuator: the hydraulic cylinder: is installed between the wire and the suspension point of the tower to adjust the tension. The hydraulic pump station can integrate an electric or diesel-driven pump. The control valve group: includes a proportional valve, a directional valve, etc., to accurately control the flow rate and direction of the hydraulic oil. The sensing and feedback system: the displacement sensor: monitors the stroke of the hydraulic cylinder to ensure the adjustment accuracy.

[0135] Those skilled in the art will understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0136] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0137] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that realize the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0138] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0139] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0140] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for monitoring operating status faults of heavy-load overhead lines, characterized in that: The following steps are involved: The total harmonic distortion rate is obtained by injecting high-frequency test signals into heavily loaded overhead lines for predefined fault detection; According to the comparative analysis of total harmonic distortion rate and threshold, the first harmonic optimization adjustment is carried out; After the first harmonic optimization adjustment, the external load fluctuation monitoring and analysis of the heavy-load overhead line is carried out, and the second harmonic optimization adjustment is carried out according to the monitoring and analysis results of the external load fluctuation of the heavy-load overhead line; After the second harmonic optimization adjustment, the external environmental fluctuation monitoring and analysis of the heavy-load overhead line is carried out, and the third harmonic optimization adjustment is carried out based on the monitoring and analysis results of the external environmental fluctuation monitoring and analysis of the heavy-load overhead line.

2. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: The method of injecting a high-frequency test signal into a heavy-load overhead line to detect a predefined fault specifically includes: A high-frequency test signal generator is used to generate a pulse signal of a specific frequency, and the high-frequency test signal is coupled and injected into a heavy-load overhead line through a capacitive coupler; Install high-frequency sensors at receiving monitoring points to capture reflected and transmitted signals; Through spectrum analysis extraction and traveling wave positioning algorithm, the impedance abnormal points and resonance abnormal points are located.

3. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: The method of injecting a high-frequency test signal into a heavy-load overhead line to perform predefined fault detection also includes: At the downstream of the injection point or at the end of the line, the high-frequency time domain signal is obtained by sampling and collecting at the built-in sampling rate of the wide-band current transformer; The high-frequency time-domain signal is processed by fast Fourier transform to obtain the frequency-domain complex spectrum; The fundamental wave amplitude of the frequency domain complex spectrum is extracted through the heavy-load overhead line operation status fault database, and if the frequency domain amplitude value of the frequency domain complex spectrum is greater than a predefined proportion value of the fundamental wave amplitude, no adjustment is made; If the frequency domain amplitude value of the frequency domain complex spectrum is less than or equal to the predefined ratio value of the fundamental wave amplitude, filtering is performed on the part of the frequency domain complex spectrum where the corresponding frequency domain complex spectrum is less than the predefined ratio value of the corresponding fundamental wave amplitude; The total harmonic distortion rate of heavy-load overhead lines is obtained by extracting and analyzing the complex spectrum in the frequency domain.

4. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: The first harmonic optimization adjustment specifically includes: If the total harmonic distortion rate of the heavy-load overhead line is less than the total harmonic distortion rate threshold, no adjustment will be made; If the total harmonic distortion rate of the heavily loaded overhead line is equal to or greater than the total harmonic distortion rate threshold, the passive filter is activated at a predefined position for harmonic suppression through passive filter tuning.

5. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: After the first harmonic optimization adjustment, the external load fluctuation monitoring and analysis of the heavy-load overhead line is performed, specifically including: Directly extract the historical average value of the load power of the heavy-load overhead line, the historical average value of the leakage current of the heavy-load overhead line, and the average value of the discharge intensity of the partial discharge from the heavy-load overhead line database; The maximum load power value and the minimum load power value of the heavy-load overhead line are obtained by detecting the heavy-load overhead line intelligent monitoring terminal; The maximum leakage current of the heavy-load overhead line is obtained by detecting the corresponding leakage current acquisition loop; The maximum discharge intensity of partial discharge of heavy-load overhead lines is obtained by detecting with a corresponding high-frequency partial discharge detector; The difference between the maximum load power of the heavy-load overhead line and the minimum load power of the heavy-load overhead line is analyzed with the historical average load power of the heavy-load overhead line, and then the weight factor of the load power is corrected with the corresponding humidity to obtain the first negative impact component of the external load fluctuation of the heavy-load overhead line; The first proportional value is obtained by performing an exponential correction on the ratio of the maximum leakage current of the heavy-load overhead line to the historical average leakage current of the heavy-load overhead line, and the second proportional value is obtained by performing a multiple joint analysis on the ratio of the maximum discharge intensity of the local discharge of the heavy-load overhead line to the average discharge intensity of the local discharge of the heavy-load overhead line and the discharge times of the discharge intensity of the local discharge of the heavy-load overhead line, and the first proportional value is superimposed on the second proportional value, and then corrected with the weight factor of the humidity on the local and leakage discharge, to obtain the negative second impact component of the external load fluctuation of the heavy-load overhead line; The negative impact value of the external load fluctuation of the heavy-load overhead line is obtained by comprehensively analyzing the first negative impact component of the external load fluctuation of the heavy-load overhead line and the second negative impact component of the external load fluctuation of the heavy-load overhead line.

6. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: The second harmonic optimization adjustment according to the external load fluctuation monitoring and analysis results of the heavy-load overhead line specifically includes: If the negative impact value of the external load fluctuation of the heavy-load overhead line is less than the negative threshold value of the external load fluctuation of the heavy-load overhead line, the second harmonic optimization adjustment is not performed; If the negative impact value of the external load fluctuation of the heavy-load overhead line is equal to or greater than the negative threshold value of the external load fluctuation of the heavy-load overhead line, the negative impact value of the external load fluctuation of the heavy-load overhead line is subtracted from the negative threshold value of the external load fluctuation of the heavy-load overhead line to obtain the negative difference value of the external load fluctuation of the heavy-load overhead line; According to the negative difference of the external load fluctuation of the heavy-load overhead line and the predefined load fluctuation negative difference matching rule, the period window of the fast Fourier transform is reduced and the overlap rate of the fast Fourier transform is increased.

7. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: After the second harmonic optimization adjustment, the external environmental fluctuation monitoring and analysis of the heavy-load overhead line is carried out, specifically including: The maximum value of the conductor mechanical stress and the maximum value of the conductor swing amplitude corresponding to the acquisition of the heavy-load overhead line by the fiber Bragg grating sensor; If the maximum value of the mechanical stress or the maximum value of the wire swing amplitude is greater than or equal to the corresponding threshold value, the hydraulic tension adjustment device is activated; If the maximum value of mechanical stress or the maximum value of conductor swing amplitude is less than the corresponding threshold, no adjustment is made. The standard value of line mechanical stress, the standard value of conductor swing amplitude and the capacitance threshold of heavy-load overhead line are directly extracted from the database of heavy-load overhead lines. The maximum value of heavy-load overhead line capacitance and the minimum value of heavy-load overhead line capacitance are collected by distributed capacitance sensors. The ratio of the maximum value of conductor mechanical stress to the standard value of conductor mechanical stress is corrected with the conductor mechanical stress weight factor to obtain the first negative component of the external environment of heavy-load overhead line. The ratio of the maximum value of conductor swing amplitude to the standard value of conductor swing amplitude is corrected with the conductor swing amplitude weight factor to obtain the second negative component of the external environment of heavy-load overhead line. The difference between the maximum value of heavy-load overhead line capacitance and the minimum value of heavy-load overhead line capacitance is analyzed and compared with The proportional analysis of the capacitance threshold of the heavy-load overhead line is then corrected with the capacitance weight factor of the heavy-load overhead line to obtain the negative third component of the external environment of the heavy-load overhead line. The negative impact value of the external load fluctuation of the heavy-load overhead line, the negative first component of the external environment of the heavy-load overhead line, the negative second component of the external environment of the heavy-load overhead line and the negative third component of the external environment of the heavy-load overhead line are combined to obtain the negative impact value of the external environment of the heavy-load overhead line. The negative impact value of the external environment of the heavy-load overhead line is used to represent the quantitative level of the degree of influence of the external load fluctuation of the heavy-load overhead line on the heavy-load overhead line by the negative impact value of the external load fluctuation of the heavy-load overhead line, the negative first component of the external environment of the heavy-load overhead line, the negative second component of the external environment of the heavy-load overhead line and the negative third component of the external environment of the heavy-load overhead line.

8. The operating status fault monitoring method for heavy-load overhead lines according to claim 1, characterized in that: The third optimization adjustment of harmonics according to the monitoring and analysis results of the external environmental fluctuations of the heavy-load overhead line specifically includes: If the negative impact value of the external environment of the heavy-load overhead line is less than the negative impact threshold of the external environment of the heavy-load overhead line, no adjustment will be made; If the negative impact value of the external environment of the heavy-load overhead line is equal to or greater than the negative impact threshold of the external environment of the heavy-load overhead line, the heavy-load overhead line at the corresponding injection point is spread spectrum gain through a predefined broadband coupler and nonlinear notch filtering is performed on the predefined frequency.

9. A system for monitoring the operating status of a heavy-load overhead line, characterized in that: It includes a predefined fault detection module, a first harmonic optimization and adjustment module, a second harmonic optimization and adjustment module, and a third harmonic optimization and adjustment module; A predefined fault detection module is used to detect predefined faults by injecting high-frequency test signals into heavy-load overhead lines to obtain the total harmonic distortion rate; A harmonic first optimization adjustment module is used to perform harmonic first optimization adjustment based on the comparison and analysis between the total harmonic distortion rate and the threshold value; A harmonic second optimization adjustment module is used to monitor and analyze the external load fluctuation of the heavy-load overhead line after the first harmonic optimization adjustment, and perform the second harmonic optimization adjustment according to the monitoring and analysis results of the external load fluctuation of the heavy-load overhead line; The harmonic third optimization adjustment module is used to monitor and analyze the external environmental fluctuations of heavy-load overhead lines after the harmonic second optimization adjustment, and to perform the harmonic third optimization adjustment based on the monitoring and analysis results of the external environmental fluctuations of heavy-load overhead lines.

10. A device using the method for monitoring operating status faults of heavy-load overhead lines as claimed in any one of claims 1 to 8, characterized in that: It includes a hydraulic cylinder of a hydraulic tension regulating device, a hydraulic pump station of a hydraulic tension regulating device, a control valve group of a hydraulic tension regulating device, a sensor module of a hydraulic tension regulating device, a control module of a hydraulic tension regulating device, a communication module of a hydraulic tension regulating device and a protective housing of a hydraulic tension regulating device: Hydraulic tension adjustment device Hydraulic cylinder: used to change the effective length of the wire by extending and retracting the piston rod; Hydraulic tension adjustment device hydraulic pump station: used to provide high-pressure oil source to drive the hydraulic cylinder to move; Hydraulic tension adjustment device control valve group: used to control the flow and direction of hydraulic oil; Hydraulic tension adjustment device sensing module: used to detect feedback through fiber grating sensors; Hydraulic tension adjustment device control module: used for embedded controller to receive sensor signals and output adjustment instructions according to PID control; Communication module for hydraulic tension adjustment device: used to link with the operation status fault monitoring system of heavy-load overhead lines, supporting remote commands and status feedback; Hydraulic tension adjustment device protective housing: used for corrosion resistance, rain and dust resistance, with IP67 protection grade.

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