Transient low-energy signal identifying and positioning method and system based on high-voltage cable

Abstract

The invention discloses a transient low-energy signal identification and positioning method and system based on a high-voltage cable. The method comprises the following steps: acquiring operation state data of a plurality of monitoring points on a cable line; extracting a power frequency signal of the operation state data of each monitoring point; calculating and determining the deviation between the operation state data of each monitoring point and the power frequency signal thereof, and taking the deviation as a residual signal of each monitoring point; extracting a transient pulse signal from the residual signal of each monitoring point; and determining the type of the transient pulse signal according to the change trend of the transient signals of the plurality of monitoring points on the cable line at the same time. Accurate extraction and identification of the low-energy transient pulse signal of the high-voltage cable are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment state monitoring and fault diagnosis, and particularly relates to a high-voltage cable transient small energy signal identification and positioning method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] In the long-term operation of high-voltage cables and their joints, early fault phenomena such as partial discharge may occur due to insulation aging, manufacturing process defects, or mechanical damage. These faults, in the initial stage, are characterized by extremely small amplitude and extremely short duration transient pulse signals. However, these weak defect signals (endogenous signals) are not only overwhelmed by the powerful power frequency (50Hz / 60Hz) current signals, but also easily confused with transient interferences (exogenous signals) from the outside of the system (such as adjacent equipment operation, environmental electromagnetic noise, etc.).

[0004] In related technologies, the current signals of each monitoring point of the cable are collected through a high-frequency current transformer (HFCT), and then the transient signals are directly extracted from the obtained current signals to determine the type of the transient signals.

[0005] However, the above method has the problems of difficulty in extracting transient signals and inability to accurately determine the amplitude of the transient signals, which further leads to inaccurate determination of the type of the transient signals. SUMMARY

[0006] To solve the above problems, the present application proposes a high-voltage cable transient small energy signal identification and positioning method and system, which realizes accurate extraction of transient signals and accurate determination of the type of the transient signals.

[0007] To achieve the above purpose, the present application adopts the following technical solutions: In a first aspect, the high-voltage cable transient small energy signal identification and positioning method comprises: obtaining the operating state data of a plurality of monitoring points on the cable line; extracting the power frequency signal of the operating state data of each monitoring point; calculating and determining the deviation between the operating state data of each monitoring point and its power frequency signal as the residual signal of each monitoring point; extracting the transient pulse signal from the residual signal of each monitoring point; determining the type of the transient pulse signal according to the change trend of the transient signals of the plurality of monitoring points on the cable line at the same time.

[0008] Further, the operating state data includes three-phase operating current, three-phase grounding current, and total grounding current.

[0009] Further, the transient pulse signal is a signal with an amplitude greater than a set amplitude threshold in the residual signal.

[0010] Further, when the change trend of the transient signals of the multiple monitoring points on the cable line at the same time is that the amplitudes of the signals present monotonic attenuation from one end to the other end along the cable path, and the waveforms of the signals are consistently distorted, the type of the transient pulse signal is determined as an external source signal.

[0011] Further, when the change trend of the transient signals of the multiple monitoring points on the cable line at the same time is that the amplitudes of the signals present attenuation from a certain point in the middle to both sides, the type of the transient pulse signal is determined as an internal source signal.

[0012] Further, when the type of the transient pulse signal is an internal source signal, the position of the fault point is determined according to the change trend of the transient signals of the multiple monitoring points on the cable line at the same time.

[0013] In a second aspect, a high-voltage cable transient small-energy signal identification and positioning system is provided, comprising: a data acquisition unit configured to acquire operating state data of multiple monitoring points on a cable line; a power frequency signal extraction unit configured to extract a power frequency signal of the operating state data of each monitoring point; a residual signal calculation unit configured to calculate a deviation between the operating state data of each monitoring point and the power frequency signal thereof as a residual signal of each monitoring point; a pulse signal extraction unit configured to extract a transient pulse signal from the residual signal of each monitoring point; the type of the transient pulse signal is determined according to the change trend of the transient signals of the multiple monitoring points on the cable line at the same time.

[0014] In a third aspect, a computer device is provided, comprising: a processor adapted to execute a computer program; a computer readable storage medium having a computer program stored therein, wherein the computer program is executed by the processor to implement the high-voltage cable transient small-energy signal identification and positioning method according to the first aspect.

[0015] In a fourth aspect, a computer readable storage medium is provided, wherein the computer readable storage medium stores a computer program, and the computer program is adapted to be loaded and executed by a processor to implement the high-voltage cable transient small-energy signal identification and positioning method according to the first aspect.

[0016] In a fifth aspect, a computer program product is provided, which comprises a computer program, and when the computer program is executed by a processor, the method for identifying and positioning based on a high-voltage cable transient small energy signal is realized.

[0017] Compared with the prior art, the present application has the following beneficial effects: The method for identifying and positioning based on a high-voltage cable transient small energy signal provided by the present application firstly removes the power frequency signal in the original operation state data before extracting the transient pulse signal, which removes most of the defect transient signals and noise after the power frequency interference in the original signal, realizes effective identification and extraction of the transient signal, and then realizes accurate determination of the type of the transient pulse signal by using the change trend of the transient signal at the same time of the multiple monitoring points on the cable line, which plays a crucial role in realizing the true "intelligent early warning" and "precise operation and maintenance" of the high-voltage cable, guarantees the long-term stable operation of the high-voltage cable and its joint, and guarantees the safety and reliability of power supply.

[0018] The advantages of the additional aspects of the present application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application should not be limited by the accompanying drawings.

[0020] Figure 1 The flow chart of the method for identifying and positioning based on a high-voltage cable transient small energy signal provided by the present application. DETAILED DESCRIPTION

[0021] The present application will be further described below in combination with the drawings and embodiments.

[0022] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0023] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form, and in addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, they indicate the presence of the features, steps, operations, devices, components and / or combinations thereof.

[0024] In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0025] Firstly, the application scenario of the method for identifying and positioning based on the transient small energy signal of the high-voltage cable proposed in the embodiments of the application is described.

[0026] The method for identifying and positioning based on the transient small energy signal of the high-voltage cable proposed in the embodiments of the application is applied to the application scenario of identifying and positioning the transient signal in the high-voltage cable line.

[0027] The high-voltage cable and its joint will produce early fault phenomena such as partial discharge due to insulation aging, manufacturing process defects or mechanical damage in long-term operation. These faults show extremely small amplitude and extremely short duration transient pulse signals in the initial stage. However, these weak defect signals (endogenous signals) are not only overwhelmed by the strong power frequency (50Hz / 60Hz) load current signal, but also easily confused with transient interference (exogenous signals) from the outside of the system (such as adjacent equipment operation, environmental electromagnetic noise, etc.).

[0028] In the related art, there is a technical solution that acquires the current signals of each monitoring point of the cable through a high-frequency current transformer (HFCT), and then extracts the transient signal from the acquired current signal to determine the type of the transient signal.

[0029] Although the method in the related art can acquire high-frequency signals, there are two major bottlenecks: (1) Transient signal extraction problem: The strong power frequency background signal makes the signal-to-noise ratio extremely low, and it is extremely difficult to observe and extract weak transient signals from raw data, making it difficult to obtain real amplitude information.

[0030] (2) Transient signal identification problem: Even if the transient signal is extracted, it is difficult to effectively distinguish whether the signal is an "endogenous signal" representing internal insulation problems of the cable or an "exogenous interference" from the external environment. This leads to a high false alarm rate, and the operation and maintenance personnel cannot intervene in real-time and effectively to the real internal defects.

[0031] Therefore, developing a method that can extract weak transient signals from strong power frequency noise and accurately identify their source is crucial for realizing the true "intelligent early warning" and "precise operation and maintenance" of high-voltage cables.

[0032] The application proposes a high-voltage cable transient small energy signal identification positioning method to solve the above problems, which can not only effectively extract weak transient pulse signals from strong power frequency noise in the high-voltage cable line, but also reliably distinguish whether the transient pulse signal is derived from internal defects of the cable (internal source signal) or external interference (external source signal), plays a crucial role in realizing the true "intelligent early warning" and "precise operation and maintenance" of the high-voltage cable, and guarantees the long-term stable operation of the high-voltage cable and its joint and the safe and reliable power supply.

[0033] As shown in Figure 1 The high-voltage cable transient small energy signal identification positioning method proposed by the embodiment of the application comprises: obtaining operation state data of a plurality of monitoring points on a cable line; extracting a power frequency signal of the operation state data of each monitoring point; calculating a deviation between the operation state data of each monitoring point and the power frequency signal thereof as a residual signal of each monitoring point; extracting a transient pulse signal from the residual signal of each monitoring point; determining a transient pulse signal type according to a change trend of the transient signals of the plurality of monitoring points on the cable line at the same time.

[0034] The high-voltage cable transient small energy signal identification positioning method proposed by the embodiment of the application first removes the power frequency signal in the original operation state data before extracting the transient pulse signal, which removes most of the defect transient signals and noise after the power frequency interference in the original signal, realizes effective identification and extraction of the transient signal, and then uses the change trend of the transient signals of the plurality of monitoring points on the cable line at the same time to accurately determine the transient pulse signal type, which plays a crucial role in realizing the true "intelligent early warning" and "precise operation and maintenance" of the high-voltage cable, guarantees the long-term stable operation of the high-voltage cable and its joint, and guarantees the safe and reliable power supply.

[0035] In some embodiments, the obtained operation state data of each monitoring point comprises three-phase operation currents, three-phase grounding currents and total grounding currents.

[0036] The embodiment of the application arranges at least two monitoring points along the cable line, usually sets the monitoring points at the cable joints, and the distance between the adjacent two monitoring points is known as L, which is determined according to the actual demand of the cable, such as the high-voltage cable usually has a segment spacing of about 500 meters.

[0037] Each monitoring point is provided with 8 data channels to collect the main cable operation current and the grounding current of the protective layer. The data collected by the 8 data channels are usually ABC three-phase operation currents, ABC three-phase grounding currents and total grounding currents, and the remaining one data channel is empty.

[0038] The application collects the operation state data of each monitoring point at a sampling frequency fs (fs≥20KHz). The length of the data of each monitoring point collected each time is 100ms, ensuring the capture of multiple complete power frequency cycles.

[0039] Suppose the operation state signal of the ith monitoring point triggered at time t is .

[0040] In some embodiments, the power frequency signal of each monitoring point operation state data is extracted; The deviation between the operation state data of each monitoring point and its power frequency signal is calculated and determined as the residual signal of each monitoring point.

[0041] The embodiments of the application model and predict the 50Hz power frequency component and its main harmonics in the operation state signal of each monitoring point collected at the same time .

[0042] Specifically, adaptive filtering or least square method fitting is used to determine the power frequency signal in the operation state signal :

[0043] wherein, f 0=50Hz, H is the harmonic number of fitting (usually H ≥5), and are the amplitude and phase of the nth harmonic in the operation state signal of the ith monitoring point i . h The operation state signal of the ith monitoring point is subtracted by the power frequency signal extracted from the signal

[0044] , to obtain the residual signal of the ith monitoring point i : i The residual signal contains the defect transient signal and noise after removing most of the power frequency interference. When the residual signal is used for transient signal extraction and identification, the accuracy of transient signal extraction and identification is ensured.

[0045] In some embodiments, the transient pulse signal is the signal with an amplitude greater than a set amplitude threshold in the residual signal.

[0046] In some embodiments, the transient pulse signal is the signal with an amplitude greater than a set amplitude threshold in the residual signal.

[0047] ​​​This invention extracts transient pulse signals from pulse signals at each monitoring point by setting an amplitude threshold. The process includes: Determine the operating status signal of the monitoring point Standard deviation of the pulse-free interval Data collected before the trigger acquisition time is considered to be in a pulse-free interval. Standard deviation is used to measure the dispersion or fluctuation of data in pulse-free intervals; According to standard deviation Calculate and determine the operating status signal amplitude threshold ,in, k is a coefficient, usually taken as 3 to 5; Extracting residual signals with amplitudes greater than an amplitude threshold The signal, as the first i Transient pulse signals from each monitoring point. Key features of the transient pulse signal at each monitoring point are extracted, including signal amplitude. Waveform and the time of occurrence of transient signals Where i represents the i-th monitoring point, j represents the j-th transient pulse signal detected by that monitoring point, and the subscript 0 indicates the start time of the pulse.

[0048] In some embodiments, when the transient signal at multiple monitoring points on a cable line changes at the same time with the signal amplitude monotonically decreasing from one end to the other along the cable path and the waveform of the signal undergoing consistent distortion, the transient pulse signal type is determined to be an external signal.

[0049] When the transient signal at multiple monitoring points on a cable line changes in a trend where the amplitude of the signal decreases from a certain point in the middle to both sides along the cable path, the transient pulse signal type is determined to be an internal signal.

[0050] When the transient pulse signal type is an internal signal, the location of the fault point is also determined based on the changing trend of the transient signals at multiple monitoring points on the cable line at the same time.

[0051] This invention describes a method for identifying the source of transient signals and determining the type of transient pulse signals by analyzing the spatial propagation characteristics of transient signals within the same time window ΔT extracted from multiple monitoring points on a cable line. Assume there are N monitoring points on the cable line, defined sequentially as M1, M2, ..., MN along the cable's power supply side → power receiving side path.

[0052] If the amplitude of the transient signal at multiple monitoring points on the cable line at the same time presents a trend of monotonic attenuation from one end to the other end along the cable path, and the waveform presents consistent distortion (such as pulse broadening), it is determined that the signal is more likely to be an external interference signal from one end of the cable line, and the type of the transient pulse signal is determined to be an exogenous signal.

[0053] Specifically, the specific determination condition for determining that the type of the transient pulse signal is an exogenous signal includes: (1) Assuming that the signal originates from the outside of the monitoring point M1, the amplitudes of the transient signals at multiple monitoring points on the cable line should satisfy the approximate relationship: > >…>

[0054] (2) The pulse arrival times at each monitoring point should satisfy < <…< , and the time difference is consistent with the monitoring point spacing L and the electromagnetic wave propagation speed v in the cable (ΔT ≈ L / v).

[0055] (3) The pulse width is broadened with the increase of the propagation distance, FWHM( )<FWHM( )<…<FWHM( ), where FWHM is the full width at half maximum of the pulse.

[0056] If the amplitudes of the transient signals at multiple monitoring points on the cable line at the same time present a trend of attenuation from a certain point in the middle to both sides, it is determined that the signal is more likely to be an internal defect signal originating from a certain point inside the cable line, and the type of the transient pulse signal is determined to be an endogenous signal.

[0057] Specifically, the specific determination condition for determining that the type of the transient pulse signal is an endogenous signal includes: (1) There is a monitoring point Mk(1<K<N) whose transient signal amplitude is the largest and monotonically decreases to both sides: <… < …>

[0058] Positioning formula: fault point position X fault The amplitude attenuation law can be used for preliminary positioning. An exponential attenuation model is adopted, and by fitting the amplitudes of the transient signals at the monitoring points and their positions , the fault position can be estimated and determined. A simplified linear interpolation positioning (applicable to three monitoring points) is:

[0059] (2) Time arrival characteristic: the pulse arrival time of each monitoring point is also centered on M k and increases to both sides.

[0060] The high-voltage cable transient small energy signal identification and positioning method provided by the embodiment can effectively extract weak transient small energy pulse signals from strong power frequency noise in the high-voltage cable line, can reliably distinguish whether the small signals are from internal defects of the cable or external interference, and can realize true "intelligent early warning" and "precise operation and maintenance" of the high-voltage cable through analysis of the signals, thereby ensuring long-term stable operation of the high-voltage cable and its joint and ensuring the safety and reliability of power supply.

[0061] The embodiment further provides a high-voltage cable transient small energy signal identification and positioning system, which comprises: a data acquisition unit configured to acquire operation state data of a plurality of monitoring points on a cable line; a power frequency signal extraction unit configured to extract a power frequency signal of the operation state data of each monitoring point; a residual signal calculation unit configured to calculate a deviation between the operation state data of each monitoring point and the power frequency signal thereof as a residual signal of each monitoring point; a pulse signal extraction unit configured to extract a transient pulse signal from the residual signal of each monitoring point; determine the type of the transient pulse signal according to the change trend of the transient signals of the plurality of monitoring points at the same time on the cable line.

[0062] It should be noted that the high-voltage cable transient small energy signal identification and positioning system provided in the above embodiment is only used as an example to illustrate the division of the above functional modules during extraction and positioning of the high-voltage cable transient pulse signal, and in actual application, the above functions can be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the high-voltage cable transient small energy signal identification and positioning system provided in the above embodiment and the high-voltage cable transient small energy signal identification and positioning method embodiment belong to the same concept, and the specific implementation process is described in the method embodiment, which will not be repeated here.

[0063] The application further discloses a computer device, which comprises: a processor adapted to execute a computer program; a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program is executed by the processor to realize the high-voltage cable transient small energy signal identification and positioning method provided by the embodiment.

[0064] The application further discloses a computer readable storage medium, which stores a computer program, and the computer program is suitable for being loaded by a processor and performing the high-voltage cable transient small energy signal identification and positioning method.

[0065] The application further discloses a computer program product, which comprises a computer program, and the computer program is executed by a processor to realize the high-voltage cable transient small energy signal identification and positioning method.

[0066] The method provided by the embodiments of the application can be directly embodied as hardware processor execution completion, or be executed by a combination of hardware and software modules in the processor. The software module can be located in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, a register, and other mature storage media in the field. The storage medium is located in the memory, and the processor reads information in the memory and combines the hardware to complete the steps of the above method. To avoid repetition, no longer detailed description is made herein.

[0067] Those skilled in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software mode depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.

[0068] The above describes the specific embodiments of the application in combination with the drawings, but is not a limitation on the protection scope of the application. Those skilled in the art should understand that various modifications or deformations made by the skilled person on the basis of the technical solutions of the application without creative labor are still within the protection scope of the application.

Claims

1. A method for identifying and locating a transient low-energy signal based on a high-voltage cable, characterized in that, The method comprises: acquiring operating state data of a plurality of monitoring points on a cable line; extracting power frequency signals of the operating state data of each monitoring point; calculating a deviation between the operating state data of each monitoring point and the power frequency signals thereof as a residual signal of each monitoring point; extracting a transient pulse signal from the residual signal of each monitoring point; determining a type of the transient pulse signal according to a variation trend of the transient signals of the plurality of monitoring points on the cable line at the same time.

2. The method for identifying and locating a high-voltage cable transient small energy signal based on the high-voltage cable transient small energy signal according to claim 1, wherein, The operating state data comprises three-phase operating currents, three-phase grounding currents and total grounding currents.

3. The method of claim 1, wherein, The transient pulse signal is a signal with an amplitude greater than a set amplitude threshold in the residual signal.

4. The method of claim 1, wherein, When the variation trend of the transient signals of the plurality of monitoring points on the cable line at the same time is that the amplitudes of the signals monotonically attenuate from one end to the other end along the cable path, and the waveforms of the signals are consistently distorted, the type of the transient pulse signal is determined as an external source signal.

5. The method of claim 1, wherein, When the variation trend of the transient signals of the plurality of monitoring points on the cable line at the same time is that the amplitudes of the signals attenuate from a certain point in the middle to both sides, the type of the transient pulse signal is determined as an internal source signal.

6. The method of claim 5, wherein, When the type of the transient pulse signal is the internal source signal, a fault point position is further determined according to the variation trend of the transient signals of the plurality of monitoring points on the cable line at the same time.

7. A system for identification and location based on transient low energy signals in high voltage cables, characterized in that The method comprises: a data acquisition unit configured to acquire operating state data of a plurality of monitoring points on a cable line; a power frequency signal extraction unit configured to extract power frequency signals of the operating state data of each monitoring point; a residual signal calculation unit configured to calculate a deviation between the operating state data of each monitoring point and the power frequency signals thereof as a residual signal of each monitoring point; a pulse signal extraction unit configured to extract a transient pulse signal from the residual signal of each monitoring point; a type determination unit configured to determine a type of the transient pulse signal according to a variation trend of the transient signals of the plurality of monitoring points on the cable line at the same time.

8. An electronic device, comprising: The device comprises: a processor adapted to execute a computer program; a computer readable storage medium having a computer program stored therein, the computer program being executed by the processor to implement the method for identifying and locating a transient small energy signal of a high-voltage cable according to any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is adapted to be loaded and executed by the processor to implement the method for identifying and locating a transient small energy signal of a high-voltage cable according to any one of claims 1-6.

10. A computer program product, characterised in that, The computer program product comprises a computer program, and the computer program is executed by the processor to implement the method for identifying and locating a transient small energy signal of a high-voltage cable according to any one of claims 1-6.

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