Fault detection method, device and system for overhead line based on double-ended traveling wave positioning

Abstract

This application relates to the field of line fault detection technology, specifically to a method, equipment, and system for detecting overhead line faults based on dual-end traveling wave localization. The method includes: acquiring traveling wave signals synchronously collected from both ends of an overhead line and filtering to obtain real traveling wave signals; locking the initial fault traveling wave fronts at both ends of the overhead line from the real traveling wave signals and recording the corresponding initial arrival times; calculating the energy spectrum determination coefficient and the time difference determination coefficient for the real traveling wave signals after the initial fault traveling wave fronts; performing a weighted calculation on the energy spectrum determination coefficient and the time difference determination coefficient, using the calculation results to lock the fault secondary echo in the real traveling wave signals and recording the corresponding secondary arrival time; and calculating the location of the fault point using a time difference ratio formula based on the initial arrival time and secondary arrival time at both ends of the overhead line. This improves the accuracy of overhead line fault detection.

Description

Technical Field

[0001] This application relates to the field of line fault detection technology, specifically to an overhead line fault detection method, equipment, and system based on dual-end traveling wave positioning. Background Technology

[0002] Overhead transmission lines traverse complex terrain and are exposed to the outdoors year-round, making them highly susceptible to grounding faults. Quickly and accurately locating the fault point is crucial for the reliable operation of the power grid.

[0003] However, in actual overhead transmission lines, numerous towers and T- or Y-shaped branch structures are widely distributed along the route, creating a large number of impedance discontinuities. When a fault traveling wave encounters these impedance discontinuities, complex refraction and reflection occur, resulting in a large number of false traveling wave signals (pseudo-traveling waves) at the monitoring end. These false traveling waves severely interfere with the identification of the true fault traveling wave characteristics (especially secondary reflected echoes). Traditional two-end traveling wave localization methods rely on single wavefront identification, which is prone to misjudging the traveling wavefront or echo when faced with complex reflection and refraction interference, leading to significant deviations or even complete failure in localization calculations.

[0004] Therefore, how to effectively overcome the reflection interference caused by towers or branch structures in overhead lines, accurately eliminate false traveling waves in complex waveforms and lock the real fault secondary echo, and thus achieve high-precision double-end traveling wave fault location is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, the purpose of this application is to provide a method, equipment, and system for detecting faults in overhead lines based on dual-end traveling wave positioning. The specific technical solution adopted is as follows:

[0006] In a first aspect, embodiments of this application provide an overhead line fault detection method based on dual-end traveling wave positioning, the method comprising the following steps:

[0007] Traveling wave signals synchronously acquired at both ends of the overhead line are obtained, and the traveling wave signals are sliced ​​to extract potential traveling wave signals; noise waves in the potential traveling wave signals are removed to obtain the real traveling wave signals;

[0008] By using the time difference constraint between the signal peak value and the arrival time at both ends of the line, the initial fault traveling wave fronts at both ends of the overhead line are locked in the real traveling wave signal, and the corresponding initial arrival times are recorded.

[0009] For the actual traveling wave signal after the initial fault traveling wave front, the energy spectrum determination coefficient is calculated based on the energy attenuation law including the reflection characteristics of the fault point; and the theoretical arrival time of the second echo is estimated based on the time difference of the initial arrival time at both ends of the line, and the time difference determination coefficient is calculated in combination with the actual arrival time.

[0010] The energy spectrum determination coefficient and the time difference determination coefficient are weighted and calculated. The calculation results are used to locate the fault secondary echo in the real traveling wave signal and record the corresponding secondary arrival time.

[0011] The location of the fault point is calculated using the time difference ratio formula based on the initial arrival time and the second arrival time at both ends of the overhead line.

[0012] In one embodiment, removing noise from the potential traveling wave signal to obtain the true traveling wave signal includes:

[0013] Calculate the first derivative feature of the potential traveling wave signal, and based on the first derivative feature, remove noise waves from the potential traveling wave signal by threshold segmentation to obtain the real traveling wave signal.

[0014] In one embodiment, the method of locking the initial fault traveling wavefronts at both ends of the overhead line includes:

[0015] Set a time window that includes the current actual traveling wave signal, select the actual traveling wave signal with the maximum peak value within the time window, and record it as the candidate traveling wave signal. If the time difference between the peak values ​​of the candidate traveling wave signals at both ends of the overhead line is less than the preset theoretical time, the candidate traveling wave signal is determined to be the initial fault traveling wave, and the initial fault traveling wave head is determined.

[0016] In one embodiment, the calculation process of the energy spectrum determination coefficient is as follows:

[0017] The theoretical propagation distance of the fault secondary echo to both ends of the overhead line is calculated based on the initial arrival time, and a preset energy attenuation function is input to obtain the theoretical secondary echo peak value.

[0018] The deviation between the actual peak value of the real traveling wave signal after the initial fault traveling wave front and the theoretical second echo peak value is determined, and the energy spectrum determination coefficient is negatively correlated with the deviation.

[0019] In one embodiment, the calculation process for the theoretical second echo arrival time is as follows:

[0020] Calculate the time difference between the initial arrival times at both ends of the overhead line, and combine the theoretical one-way propagation time of the traveling wave along the entire length of the overhead line with the time difference, as well as the initial arrival time at either end of the overhead line, to obtain the theoretical second echo arrival time corresponding to that end.

[0021] In one embodiment, the calculation process of the time difference determination coefficient is as follows:

[0022] Determine the actual arrival time of the real traveling wave signal after the initial fault traveling wave front at either end, calculate the absolute value of the difference between the actual arrival time and the theoretical second echo arrival time corresponding to either end, perform negative correlation mapping on the absolute value of the difference, and obtain the time difference determination coefficient.

[0023] In one embodiment, the weighted calculation is the average of the energy spectrum determination coefficient and the time difference determination coefficient.

[0024] In one embodiment, locking the fault secondary echo in the real traveling wave signal includes:

[0025] Within a preset time window after the arrival time of the initial fault traveling wave front at both ends of the overhead line, the actual traveling wave signal with the largest mean value is selected and marked as the corresponding fault secondary echo.

[0026] Secondly, embodiments of this application also provide an overhead line fault detection device based on dual-end traveling wave positioning, wherein the device stores a computer program, and when the computer program is executed by a processor, it implements the steps of any of the methods described above.

[0027] Thirdly, embodiments of this application also provide an overhead line fault detection system based on dual-end traveling wave positioning, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0028] This application has at least the following beneficial effects:

[0029] This application eliminates environmental electromagnetic interference and mechanical vibration-induced distortion pulses by slicing the traveling wave signal and removing noise waves, thus avoiding interference from external noise on waveform recognition. Through dual verification using signal peak value and double-ended time difference constraints, it eliminates occasional strong interference signals at one end, ensuring the accuracy of initial fault traveling wave front locking. It introduces energy attenuation laws incorporating fault point reflection characteristics to calculate energy spectrum determination coefficients. Utilizing the high reflectivity of grounding fault points, which significantly distinguishes them from the high refraction and low reflection properties of conventional impedance discontinuities such as existing towers or branches, it accurately isolates false reflection interference caused by line structure in the energy domain. By deriving the theoretical fault secondary echo time using the initial time difference at both ends and calculating the time difference determination coefficient, it provides physical location verification of the true secondary echo in the time domain, achieving cross-verification of energy attenuation mechanisms and time propagation laws. Among numerous complex false traveling waves with reflections, it ensures the unique and accurate locking of the true fault secondary echo, improving the accuracy and reliability of overhead line fault point detection. Attached Figure Description

[0030] Figure 1 A flowchart illustrating the steps of an overhead line fault detection method based on dual-end traveling wave positioning provided in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram showing the location of a line fault.

[0032] Figure 3 This is a schematic diagram of the traveling wave propagation in the fault area.

[0033] Figure 4 This is a schematic diagram illustrating the principle of traveling wave refraction and reflection.

[0034] Figure 5 This is a schematic diagram of interference points for overhead power lines. Detailed Implementation

[0035] The following description, in conjunction with the accompanying drawings, details the specific scheme of the overhead line fault detection method, equipment, and system based on dual-end traveling wave positioning provided in this application.

[0036] Please see Figure 1 The diagram illustrates a flowchart of an overhead line fault detection method based on dual-end traveling wave localization according to an embodiment of this application. The method includes the following steps:

[0037] S1. Acquire traveling wave signals synchronously collected from both ends of the overhead line, slice the traveling wave signals to extract potential traveling wave signals, and remove noise waves from the potential traveling wave signals to obtain the real traveling wave signals.

[0038] When a fault occurs on an overhead transmission line, specifically as follows: Figure 2 As shown, a sudden voltage change occurs at fault point K, resulting in positive and negative ground fault voltages at points X and Y of the line, respectively. Consequently, under the influence of the fault voltage components, fault traveling wave voltage and fault traveling wave current are generated and propagate along the line to both ends.

[0039] When the traveling wave signal generated at fault point K propagates along the line to both ends, when the fault traveling wave reaches the busbars at both ends of the X and Y lines, it will further reflect the signal and transmit it back to the middle of the line. A detailed diagram is shown below. Figure 3 As shown, KX1 represents the initial fault traveling wave propagating towards the X end, KX2 represents the secondary fault echo propagating towards the X end after reflection from the fault point, KY1 represents the initial fault traveling wave propagating towards the Y end, KY2 represents the secondary fault echo propagating towards the Y end after reflection from the fault point, and XY1 and YX1 both represent traveling waves formed by refraction. Assuming that in... A fault occurs at point K on the line, with a total line length of L. The initial traveling wave front arrives at the X and Y ends of the bus at the following times: and The initial traveling wave front will be further reflected when it reaches the bus terminal. When the reflected traveling wave signal reaches the fault point, it will be further refracted and reflected. Therefore, multiple traveling wave fronts can be detected at the bus terminal. Figure 3 The traveling wavefronts at the X end are denoted as follows: and Similarly, the traveling wavefront at the Y end is marked as... and .

[0040] Based on the above analysis, this embodiment deploys corresponding cable traveling wave fault location devices at both ends of the overhead line to continuously acquire traveling wave signals during power grid operation. Assuming a fault occurs at a point on the line, high-frequency transient electromagnetic waves will be generated. To acquire complete fault traveling wave signals, the sampling interval of the cable traveling wave fault location device should be on the order of nanoseconds, the sampling frequency should be no less than 20MHz, and the range of the traveling wave current sensor should be 0.1A to 200A with an accuracy of 0.1A.

[0041] Furthermore, during double-ended traveling wave localization, the traveling wave fault location devices at both ends of the cable require strict time synchronization. Therefore, an integrated module within the double-ended traveling wave fault location devices is needed to synchronize with a satellite time source, ensuring synchronized data acquisition by the fault location devices at both ends. A GPS clock source can be used, and time synchronization between the traveling wave detection devices at both ends of the power distribution line can be achieved through hardware and the PTP time synchronization protocol.

[0042] When a fault occurs at a certain location K on an overhead line at a certain moment, a high-frequency transient traveling wave signal will be generated. In this embodiment, a current signal is used as an example to analyze the fault traveling wave; therefore, the traveling wave signal in this embodiment is a current signal. The high-frequency transient traveling wave signal will be transmitted along the line and, through a series of refractions and reflections, will finally be detected by the cable traveling wave fault location device at both ends of the busbar. At the detection end, the traveling wave signal is manifested as a pulse peak, and the overall traveling wave signal exhibits a waveform distribution that rapidly reaches the peak value and gradually decays.

[0043] Therefore, for the traveling wave signal received by the detection end, a peak detection algorithm and baseline correction are used to treat the signal between two adjacent baseline segments as a potential traveling wave signal. The resulting potential traveling wave signal may be a real fault traveling wave, a pseudo traveling wave formed by interference points, or a noise wave formed by environmental noise.

[0044] In practice, electromagnetic noise often exists during signal transmission in a line, further causing waveform distortion and thus forming noise waves. These noise waves are generated by external interference factors and are not traveling wave signals produced by actual fault conditions. Therefore, it is necessary to filter and remove noise waves from all potential traveling wave signals.

[0045] First, the propagation speed of the fault traveling wave can be obtained based on the basic signal estimation of the line. For example, for a transmission line 200km long, with 3 phases and a signal frequency of 50Hz, the corresponding positive-sequence inductance is: The positive sequence capacitance is Substitute this data into the wave speed estimation formula. So, what is the propagation time of the fault traveling wave on the line? .

[0046] Taking the traveling wave signal at line X as an example, with the peak time of the current single potential traveling wave signal as the center, 2 values ​​are obtained before and after. The time window is defined by analyzing the differences between the current potential traveling wave signal and other potential traveling wave signals to filter noise waves. The peak time is the time corresponding to the maximum value. It should be noted that this embodiment performs overhead line fault detection based on acquiring sufficient traveling wave signals, thus avoiding situations where future times exist within the time window of acquiring a single potential traveling wave signal. If the current potential traveling wave signal is the last potential traveling wave signal acquired during overhead line fault detection, then only the time two seconds prior to the peak time of that potential traveling wave signal are selected. The time window.

[0047] Furthermore, for the real traveling wave signal generated at the fault point, due to the abrupt change of the ground fault, the traveling wave signal has a fast rising edge and obvious high-frequency components. Conversely, for the spurious traveling wave signal generated by noise factors, due to environmental noise such as electromagnetic noise and mechanical vibration, the noise wave exhibits a slow rising edge, weak high-frequency components, and is prone to distortion.

[0048] Therefore, based on the transition characteristics of the rising edge of a single potential traveling wave signal, a distinguishing feature value is constructed: In the formula, This represents the distinguishing characteristic value of the current potential traveling wave signal at the X end of the line. This indicates that the first derivative of the current potential traveling wave signal is calculated, and max{} indicates that the maximum value is obtained.

[0049] Finally, within the time window of the current potential traveling wave signal at line X, the distinguishing feature values ​​of all potential traveling wave signals are calculated, and the noise wave and the real traveling wave signal are distinguished by the magnitude of the distinguishing feature values.

[0050] In this embodiment, a threshold segmentation method is used. The mean of the distinguishing feature values ​​of all potential traveling wave signals within the current potential traveling wave signal time window is calculated and used as the segmentation threshold. Potential traveling wave signals with distinguishing feature values ​​less than the segmentation threshold are marked as noise waves, and other potential traveling wave signals are marked as real traveling wave signals. Among them, real traveling wave signals include real fault traveling waves and pseudo traveling waves.

[0051] S2, by using the time difference constraint between the signal peak value and the arrival time at both ends of the line, locks the initial fault traveling wave front at both ends of the overhead line in the real traveling wave signal and records the corresponding initial arrival time.

[0052] When a fault occurs at a point on an overhead line, the resulting transient traveling wave signal will propagate along the line. If, during its propagation along a single line, it encounters a tower or line branch structure, there may be a change in impedance value, i.e., an impedance discontinuity. This will cause reflection and refraction of the transient traveling wave signal at the impedance discontinuity, resulting in additional traveling wave signals, i.e., pseudo-traveling wave signals, that can be detected at both ends of the busbar due to the impedance discontinuity.

[0053] The refraction and reflection of traveling waves are basically related to the corresponding impedance, and the corresponding refraction and reflection principle diagram is as follows: Figure 4 As shown, an impedance discontinuity occurs at the dashed line, corresponding to the impedances at both ends of the line as follows: and , Figure 4 In the diagram, 1 represents the incident traveling wave, 2 represents the reflected traveling wave, and 3 represents the refracted traveling wave.

[0054] Calculate the corresponding refractive index based on existing formulas. and reflection coefficient They are respectively:

[0055]

[0056] At impedance discontinuities such as those on towers or branch lines, the detection of the secondary traveling wave of a fault is often only affected, not the initial traveling wave front. Assuming a fault occurs at point K, an initial fault traveling wave KX1 will be generated from K to the X end of the line. If an impedance discontinuity exists on the line from K to X, part of the initial fault traveling wave KX1 will be refracted at this discontinuity and continue propagating in its original direction, while the other part will be reflected and propagate towards the Y end of the line. This does not affect the initial fault traveling wave KX1 reaching the X end. Therefore, impedance discontinuities only affect the detection of the secondary fault echo, not the initial traveling wave front.

[0057] By eliminating noise waves caused by noise interference, the selected real traveling wave signals are further analyzed to determine the initial fault traveling wave front. When a ground fault occurs on a high-voltage transmission line, the generated initial traveling wave energy is high. Therefore, among the selected real traveling wave signals, the initial traveling wave front has the highest energy intensity, which is used to determine the initial traveling wave front. This embodiment performs a dual determination, specifically:

[0058] Judgment condition (1): For a single end, taking the X end as an example, divide the time window for a single real traveling wave signal, take the current peak value of the real traveling wave signal as the midpoint of the time, and obtain 2... Get 2 from the next step As a time window, the actual traveling wave signal with the maximum peak value within the current time window is selected and denoted as the candidate traveling wave signal. The time corresponding to the peak value of the candidate traveling wave signal is obtained and denoted as the arrival time of the initial traveling wave front. .

[0059] Judgment condition (2): If the initial traveling wave front can be determined and filtered at the X end, then the initial traveling wave front at the Y end within the corresponding time window and the corresponding arrival time are obtained. Since the X and Y ends are strictly time-synchronized, the traveling wave generated by a real fault will propagate to both ends simultaneously. Theoretically, the arrival time difference of the initial traveling wave front at both ends must be less than the total transmission time from the X end to the Y end. Therefore, the time judgment is set as follows: In this embodiment, considering the possibility of slight deviations in time synchronization between the two ends, the theoretical formula is amplified by setting a fault tolerance coefficient k, i.e. k is set to 1.01~1.05. In this embodiment, k=1.03.

[0060] Only when both conditions (1) and (2) are met simultaneously, the candidate traveling wave signal is determined to be the initial fault traveling wave. If the conditions are not met, the determination is deemed unqualified, and the analysis needs to be performed again on the next real traveling wave signal. In addition, after obtaining the arrival time of the initial fault traveling wave fronts at both ends of the line, the end that arrives first is marked as the near end, and the other end is marked as the far end. In this embodiment, the X end is taken as the near end for analysis.

[0061] S3, for the actual traveling wave signal after the initial fault traveling wave front, calculates the energy spectrum determination coefficient based on the energy attenuation law including the reflection characteristics of the fault point; and calculates the theoretical arrival time of the second echo based on the time difference of the initial arrival time at both ends of the line, and calculates the time difference determination coefficient in combination with the actual arrival time.

[0062] When a traveling wave propagates on a uniform transmission line, it encounters points of impedance discontinuity, such as fault points, towers, and branching points. Some of the energy is reflected, and some is refracted. Based on the law of conservation of energy, the sum of the refracted and reflected waves equals the energy of the incident wave. The difference in impedance change at fault points and interference points determines the corresponding reflection and refraction coefficients, from which the corresponding energy attenuation trend can be derived.

[0063] For overhead lines, impedance changes occur not only at the fault point but also at impedance discontinuities such as towers and branching points. At these discontinuities, traveling waves undergo refraction and reflection, as illustrated in the diagram below. Figure 5 As shown. In Figure 5 In this context, K represents the actual fault point, while P represents the impedance discontinuity point caused by the normal structure on the line. When the fault traveling wave passes through each impedance discontinuity point, it will generate corresponding refracted and reflected waves. These refracted and reflected waves will be detected when they reach the detection end, which greatly increases the difficulty of identifying the secondary reflected waves in the actual fault traveling wave.

[0064] There is a significant difference in impedance distribution between the actual fault point and the impedance discontinuity point. The impedance of a typical line is 400Ω~500Ω, varying slightly depending on the line material. When a fault occurs, a corresponding transition impedance is generated at the fault point. Due to the short-circuit grounding fault, this transition impedance is often lower, typically between 20Ω and 50Ω, resulting in a large impedance difference between the two. Therefore, when a traveling wave reaches the actual fault point, more of its energy is reflected, and less is refracted. At impedance discontinuities, usually towers or branching points, although there is some impedance difference, the overall difference from the line impedance is smaller. Thus, at impedance discontinuities, more energy is refracted, and less is reflected.

[0065] Based on the impedance differences corresponding to the aforementioned fault points and impedance discontinuities, the refractive index and reflection index calculated from the impedance differences, and the energy attenuation, the energy spectrum determination coefficient is calculated. Taking the X end as an example, for each real traveling wave signal after the initial fault traveling wave front (which may be a pseudo-traveling wave generated by the interference point or a secondary reflected wave corresponding to the fault point), the energy spectrum determination coefficient is obtained based on the energy attenuation, and the expression is:

[0066] In the formula, This represents the energy spectrum determination coefficient of the i-th actual traveling wave signal after the initial fault traveling wave front at line X end. This represents the peak value corresponding to the i-th real traveling wave signal. This represents the preset energy decay function, and norm() represents the normalization function. This represents a preset, extremely small constant greater than 0, used to avoid a denominator of 0. In this embodiment... The implementer can set the parameters according to the actual situation. In this embodiment, the energy decay function is: ,in, Let e ​​be the actual peak value of the traveling wave front at the initial fault at end X of the line, λ be the natural constant, and λ be the inherent traveling wave attenuation constant of the overhead line, a known empirical constant determined by basic parameters such as line material and wire diameter. In this embodiment, the preset reflection attenuation coefficient is used. D is the theoretical propagation distance of the input, i.e., the distance from the input to the output in the formula. The calculated distance the secondary echo travels compared to the initial echo is given, and the calculated energy attenuation function can represent the peak value of the theoretical fault secondary echo.

[0067] In this embodiment, the norm() normalization function uses maximum-minimum normalization, and the normalization is applied to the 3rd wavefront after the initial fault traveling wave at the current end. The energy spectrum determination coefficients corresponding to the actual traveling wave signal within the time window are normalized by maximum-minimum.

[0068] In the formula for calculating the energy spectrum determination coefficient Assuming the fault traveling wave travels at the same speed from the fault point to both the X and Y ends of the line, if a fault occurs at a certain moment, then the time it takes for the fault traveling wave to reach the X end of the line is... This indicates that at the current moment, the fault traveling wave towards the Y end has reached a symmetrical distance. This indicates the time it takes for the fault traveling wave to propagate from a position symmetrical to the X end to its endpoint at the Y end. Taking the fault point as the center point and the distance to the X end as the symmetrical distance, a symmetrical point can be found at the Y end corresponding to the X end. The distance from this symmetrical point at the Y end to the endpoint at the Y end is denoted as the asymmetrical segment. This indicates the propagation time of the fault traveling wave in the asymmetric segment.

[0069] Secondly, since the fault point in this embodiment is set closer to the X end of the line, therefore, The result has a negative sign; the formula for calculating the energy spectrum determination coefficient is... Equivalent to ,and This means that the total distance L is the length of the asymmetrical segment. Subtracting the distance of the asymmetrical segment from the total distance L gives the total distance of the symmetrical segment, which is twice the distance from the fault point to the X end of the line. When the secondary echo of the real fault reaches the X end, the total distance of the traveling wave transmission is equal to the total distance of the symmetrical segment.

[0070] Correspondingly, for the Y-end of the line, the energy spectrum determination coefficient of the i-th real traveling wave signal after the initial fault traveling wave front. The calculation method is as follows: .

[0071] Therefore, after detecting the initial fault traveling wave at both ends of the line, the energy spectrum determination coefficients of each actual traveling wave signal at both ends of the line are calculated. The larger the value of the selected energy spectrum determination coefficient, the higher the probability that the corresponding actual traveling wave signal is a fault secondary echo. Conversely, the smaller the value of the energy spectrum determination coefficient, the lower the probability that the corresponding actual traveling wave signal is a fault secondary echo.

[0072] The calculation of the energy spectrum determination coefficient is based on the distance inference relationship, and it can also determine the time correlation relationship corresponding to the secondary echo of the fault. Taking the X end of the line as an example, Let represent the propagation time of the fault traveling wave in the asymmetric segment. Let represent the time required for the fault traveling wave to traverse the total distance of the symmetrical segment. Sum the result with the time length, i.e. , representing the time when the secondary echo from the fault arrives at end X. The time difference determination coefficient is obtained by comparing the theoretical time with the actual time; the specific expression is as follows:

[0073] In the formula, This represents the time difference determination coefficient of the i-th actual traveling wave signal after the initial fault traveling wave front at line X end. This represents the time corresponding to the peak value of the i-th real traveling wave signal, and norm() represents the normalization function, which is consistent with the normalization method of the energy spectrum determination coefficient.

[0074] Correspondingly, the time difference determination coefficient of the i-th real traveling wave signal after the initial fault traveling wave front at the Y-end of the line. The expression is: .in, This indicates the arrival time of the secondary echo at the theoretical fault at end X of the line. This indicates the arrival time of the secondary echo from the theoretical fault at the Y-end of the line. This represents the theoretical one-way propagation time of a traveling wave along the entire length of an overhead line. This represents the time difference between the initial arrival times of the fault traveling waves at both ends of an overhead line. and Each represents the fusion result for each time length, while the time difference determination coefficient is the negative correlation mapping result of the fusion result. The negative correlation mapping indicates that the time difference determination coefficient is negatively correlated with the fusion result.

[0075] The arrival time of the secondary echo from the fault is theoretically calculated and compared with the actual arrival time to obtain the corresponding time difference determination coefficient. The larger the value of the time difference determination coefficient, the greater the probability that the current actual traveling wave signal is the secondary echo from the fault.

[0076] S4, perform weighted calculation on the energy spectrum determination coefficient and the time difference determination coefficient, use the calculation result to lock the fault secondary echo in the real traveling wave signal, and record the corresponding secondary arrival time.

[0077] Taking line X as an example, the energy spectrum determination coefficient and time difference determination coefficient of the i-th real traveling wave signal after the initial fault traveling wave wavefront are weighted and averaged to obtain the determination coefficient. 3 days after the arrival time of the initial fault traveling wave front Within the time window, the determination coefficients for all real traveling wave signals Sort the signals in descending order, mark the actual traveling wave signal corresponding to the maximum value of the judgment coefficient as the corresponding fault secondary echo, and record the corresponding arrival time. Similarly, the actual traveling wave signal corresponding to the maximum value of the judgment coefficient at the Y end of the line is obtained, marked as the corresponding fault secondary echo, and the corresponding arrival time is recorded. .

[0078] S5. Based on the initial arrival time and the second arrival time at both ends of the overhead line, the location of the fault point is calculated using the time difference ratio formula.

[0079] Further, based on the time difference ratio formula, the fault point of the overhead line is located, and the specific expression is as follows:

[0080]

[0081] In the formula, This indicates the distance from the fault point to the X end of the line. This represents the arrival time of the secondary echo at the Y-end of the line where the fault occurred. Therefore, the double-ended traveling wave is used to accurately locate the fault point on the overhead line. The aforementioned time difference ratio formula is a known existing technique, and the specific process will not be elaborated upon.

[0082] Based on the same inventive concept as the above methods, this application also provides an overhead line fault detection device based on dual-end traveling wave positioning. The device stores a computer program, which, when executed by a processor, implements the steps of any one of the above-described overhead line fault detection methods based on dual-end traveling wave positioning.

[0083] Based on the same inventive concept as the above methods, this application also provides an overhead line fault detection system based on dual-end traveling wave positioning, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described overhead line fault detection methods based on dual-end traveling wave positioning.

Claims

1. A fault detection method for overhead lines based on double-ended traveling wave localization, characterized in that, The method includes the following steps: Traveling wave signals synchronously acquired at both ends of the overhead line are obtained, and the traveling wave signals are sliced ​​to extract potential traveling wave signals; noise waves in the potential traveling wave signals are removed to obtain the real traveling wave signals; By using the time difference constraint between the signal peak value and the arrival time at both ends of the line, the initial fault traveling wave fronts at both ends of the overhead line are locked in the real traveling wave signal, and the corresponding initial arrival times are recorded. For the actual traveling wave signal after the initial fault traveling wave front, the energy spectrum determination coefficient is calculated based on the energy attenuation law including the reflection characteristics of the fault point; and the theoretical arrival time of the second echo is estimated based on the time difference of the initial arrival time at both ends of the line, and the time difference determination coefficient is calculated in combination with the actual arrival time. The energy spectrum determination coefficient and the time difference determination coefficient are weighted and calculated. The calculation results are used to locate the fault secondary echo in the real traveling wave signal and record the corresponding secondary arrival time. The location of the fault point is calculated using the time difference ratio formula based on the initial arrival time and the second arrival time at both ends of the overhead line.

2. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 1, characterized in that, The process of removing noise from the potential traveling wave signal to obtain the true traveling wave signal includes: Calculate the first derivative feature of the potential traveling wave signal, and based on the first derivative feature, remove noise waves from the potential traveling wave signal by threshold segmentation to obtain the real traveling wave signal.

3. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 1, characterized in that, The initial fault traveling wavefronts at both ends of the overhead line are locked, including: Set a time window that includes the current actual traveling wave signal, select the actual traveling wave signal with the maximum peak value within the time window, and record it as the candidate traveling wave signal. If the time difference between the peak values ​​of the candidate traveling wave signals at both ends of the overhead line is less than the preset theoretical time, the candidate traveling wave signal is determined to be the initial fault traveling wave, and the initial fault traveling wave head is determined.

4. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 1, characterized in that, The calculation process for the energy spectrum determination coefficient is as follows: The theoretical propagation distance of the fault secondary echo to both ends of the overhead line is calculated based on the initial arrival time, and a preset energy attenuation function is input to obtain the theoretical secondary echo peak value. The deviation between the actual peak value of the real traveling wave signal after the initial fault traveling wave front and the theoretical second echo peak value is determined, and the energy spectrum determination coefficient is negatively correlated with the deviation.

5. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 1, characterized in that, The calculation process for the theoretical second echo arrival time is as follows: Calculate the time difference between the initial arrival times at both ends of the overhead line, and combine the theoretical one-way propagation time of the traveling wave along the entire length of the overhead line with the time difference, as well as the initial arrival time at either end of the overhead line, to obtain the theoretical second echo arrival time corresponding to that end.

6. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 5, characterized in that, The calculation process for the time difference determination coefficient is as follows: Determine the actual arrival time of the real traveling wave signal after the initial fault traveling wave front at either end, calculate the absolute value of the difference between the actual arrival time and the theoretical second echo arrival time corresponding to either end, perform negative correlation mapping on the absolute value of the difference, and obtain the time difference determination coefficient.

7. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 1, characterized in that, The weighted calculation is the average of the energy spectrum determination coefficient and the time difference determination coefficient.

8. The overhead line fault detection method based on double-ended traveling wave positioning as described in claim 7, characterized in that, The process of locking the fault secondary echo in the actual traveling wave signal includes: Within a preset time window after the arrival time of the initial fault traveling wave front at both ends of the overhead line, the actual traveling wave signal with the largest mean value is selected and marked as the corresponding fault secondary echo.

9. An overhead line fault detection device based on dual-end traveling wave positioning, wherein the device stores a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-8.

10. An overhead line fault detection system based on dual-end traveling wave positioning, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-8.

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