A method, system and device for monitoring insulator flashover faults.

Abstract

This application relates to the field of transmission line insulator fault detection technology, specifically to a method, system, and device for monitoring insulator flashover faults. The method includes: acquiring leakage current data of the transmission line; analyzing the amplitude variation of the leakage current at different frequencies in the frequency domain, and then combining this with the amplitude distribution characteristics of harmonics in the frequency domain to obtain the high-frequency harmonic hazard level at each acquisition time; analyzing the leakage current pulse characteristics at each acquisition time based on the peak value variation and peak frequency in the leakage current data to obtain flashover fault characteristic values ​​at each acquisition time; and monitoring flashover faults in the transmission line insulators based on the flashover fault characteristic values. This application can improve the accuracy of detecting flashover faults in transmission line insulators.

Description

Technical Field

[0001] This application relates to the field of insulator fault detection technology for transmission lines, specifically to a method, system, and device for monitoring insulator flashover faults. Background Technology

[0002] Transmission lines are a crucial component of the power system, and their reliability directly impacts the safe and reliable operation of the power system. However, due to the environment in which transmission lines are located, various particles such as industrial exhaust gases, industrial dust, and bird droppings accumulate on the surface of transmission line insulators, forming a contamination layer. This makes the insulators susceptible to flashover faults under humid conditions. If these flashover faults are not addressed promptly, they can cause large-scale power outages, affecting the safe and reliable operation of the power system. Therefore, to ensure the safe and reliable operation of the power system, it is necessary to promptly address flashover faults in transmission line insulators, requiring accurate real-time monitoring of these faults.

[0003] In existing technologies, leakage current monitors are installed on transmission lines to monitor leakage current data. The time-domain variation characteristics of this leakage current data are then used to infer whether an insulator flashover fault has occurred, thus enabling rapid detection of insulator flashover faults on transmission lines. However, because the leakage current undergoes harmonic interference changes when a flashover fault occurs in the insulators of transmission lines, existing technologies, which rely on the time-domain variation characteristics of the leakage current for monitoring, do not fully exploit the harmonic interference features of the leakage current. This results in poor accuracy in monitoring insulator flashover faults on transmission lines, making it impossible to address these faults promptly and effectively. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method, system, and device for monitoring insulator flashover faults. The specific technical solution adopted is as follows:

[0005] In a first aspect, embodiments of this application provide a method for monitoring insulator flashover faults, comprising the following steps:

[0006] Obtain leakage current data of transmission lines;

[0007] By analyzing the amplitude variation of leakage current on the transmission line in the frequency domain, the high-frequency harmonic interference degree at each acquisition time is obtained. Then, combined with the amplitude distribution characteristics of the leakage current in the frequency domain, the high-frequency harmonic hazard degree at each acquisition time is obtained.

[0008] Based on the degree of peak variation and the frequency of peak occurrence in the leakage current data on the transmission line, the pulse anomaly degree at each acquisition time is obtained. Combined with the high-frequency harmonic hazard degree, the characteristic value of flashover fault at each acquisition time is obtained.

[0009] The flashover fault characteristics of the transmission line insulators are monitored.

[0010] Preferably, the acquisition of the high-frequency harmonic interference at each acquisition time is further described as follows:

[0011] In the formula, Let be the high-frequency harmonic interference at the t-th acquisition time. Let be the mean of the harmonic amplitude sequence at the t-th acquisition time. and Let J and (j-1) be the harmonic amplitude values ​​in the harmonic amplitude sequence at the t-th acquisition time, respectively. denoted as the number of harmonic amplitude values ​​in the harmonic amplitude sequence at the t-th acquisition time.

[0012] Preferably, the leakage current data within a preset time period before each acquisition time are arranged in chronological order to form the leakage current sequence for each acquisition time. The leakage current sequence is then transformed in the frequency domain. The amplitudes corresponding to all integer multiples of the fundamental frequency greater than 1 in the frequency domain transformed spectrum curve are arranged in ascending order of frequency to form the harmonic amplitude sequence for each acquisition time.

[0013] Preferably, the acquisition of the high-frequency harmonic hazard degree at each acquisition time further comprises:

[0014] In the formula, Let represent the high-frequency harmonic hazard level at the i-th acquisition time. Let be the high-frequency harmonic interference at the t-th acquisition time. Let be the mean of the amplitudes corresponding to all odd multiples of the fundamental frequency in the harmonic amplitude sequence at time i. Let be the mean value of the amplitudes corresponding to all even-number multiples of the fundamental frequency in the harmonic amplitude sequence at the i-th acquisition time. To avoid constants in the numerator and denominator of fractions being zero.

[0015] Preferably, peak detection is performed on the leakage current sequence at each acquisition time to extract all peak values ​​in the leakage current sequence, and the position of all peak values ​​in the leakage current sequence is counted.

[0016] Preferably, the acquisition of the pulse anomaly degree at each acquisition time is further described as follows:

[0017] In the formula, Let be the pulse anomaly degree at the t-th acquisition time. Let be the number of peak values ​​in the leakage current sequence at the t-th acquisition time. The sigmoid normalization function. and These are the i-th and (i-1)-th peak values ​​in the leakage current sequence at the t-th acquisition time, respectively. and These are the positional values ​​of the i-th and (i-1)-th peak values ​​in the leakage current sequence at the t-th acquisition time, respectively.

[0018] Preferably, the characteristic value of the flashover fault at each acquisition time is the sum of the normalized result of the high-frequency harmonic hazard degree and the normalized result of the pulse anomaly degree at each acquisition time.

[0019] Preferably, anomaly detection is performed on all flashover fault characteristic values ​​within the current acquisition time and the preset time period prior to it. If the flashover fault characteristic value at the current acquisition time is abnormal data, it indicates that an insulator flashover fault has occurred in the transmission line at this time; otherwise, no insulator flashover fault has occurred in the transmission line.

[0020] Secondly, embodiments of this application also provide an insulator flashover fault monitoring system, 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 of the above-described insulator flashover fault monitoring methods.

[0021] Thirdly, embodiments of this application also provide an insulator flashover fault monitoring device, wherein the device stores a computer program, and when the computer program is executed by a processor, it implements any of the above-described insulator flashover fault monitoring methods.

[0022] As can be seen from the above, the insulator flashover fault monitoring method, system, and device provided in this application have at least the following beneficial effects:

[0023] This application uses frequency domain analysis to extract the spectrum curve of leakage current, and analyzes the high-frequency harmonic characteristics of insulator flashover faults in transmission lines through the spectrum curve of leakage current. It accurately measures the high-frequency harmonic interference characteristics present in the leakage current, and more clearly reflects the high-frequency harmonic interference when insulator flashover faults occur, which is beneficial for subsequent accurate monitoring of insulator flashover faults in transmission lines.

[0024] Furthermore, this application fully considers the harmfulness of harmonics with odd multiples of the fundamental frequency in the leakage current. Based on the characteristics of high-frequency harmonic interference in the leakage current and the distribution of harmonic amplitude in the leakage current, it accurately measures the harmfulness of high-frequency harmonics in the leakage current of the transmission line, more fully reflecting the dangerousness of high-frequency harmonic interference in the leakage current, which is conducive to improving the accuracy of monitoring insulator flashover faults on the transmission line.

[0025] This application extracts the abnormal characteristics of leakage current pulses on transmission lines through time-domain analysis and combines the degree of harm of high-frequency harmonics in the leakage current on the transmission line to accurately measure the leakage current fault characteristics when flashover occurs in transmission line insulators. Thus, the LOF anomaly detection algorithm can accurately monitor flashover faults in transmission line insulators in real time, avoiding affecting the timeliness and effectiveness of handling flashover faults in transmission line insulators. Attached Figure Description

[0026] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A flowchart illustrating the steps of an insulator flashover fault monitoring method provided in this application. Detailed Implementation

[0028] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of an insulator flashover fault monitoring method, system, and apparatus proposed according to this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0029] Unless otherwise specified and limited, terms such as “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a circuit structure, article, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the article or device that includes said element. Furthermore, the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0030] The following description, in conjunction with the accompanying drawings, details the specific scheme of the insulator flashover fault monitoring method, system, and device provided in this application.

[0031] Please see Figure 1 The diagram illustrates a flowchart of an insulator flashover fault monitoring method according to an embodiment of this application, including the following steps:

[0032] Step 1: Obtain leakage current data of the transmission line.

[0033] To effectively and promptly address flashover faults in transmission line insulators, accurate real-time monitoring of these faults is crucial. This embodiment first installs a leakage current monitor on the transmission line under test. The monitor samples the leakage current signal in real time, and an analog-to-digital converter (ADC) converts the sampled signal into numerical values ​​to obtain the leakage current data. In this embodiment, the sampling frequency of the leakage current signal is 1 kHz. The implementer can adaptively select the sampling frequency based on the required monitoring accuracy. Higher accuracy requirements necessitate a higher sampling frequency, and vice versa.

[0034] Furthermore, in order to reduce the adverse effects of external noise interference on insulator flashover fault monitoring, in this embodiment, preferably, the leakage current data is denoised using a wavelet threshold denoising algorithm, and the leakage current data within one second before each acquisition moment is arranged in chronological order to obtain the leakage current sequence at each acquisition moment. The wavelet threshold denoising algorithm is a well-known technology, and the specific process will not be described in detail. In actual application scenarios, implementers may also use other existing denoising algorithms to denoise the leakage current data, and this embodiment does not impose any special restrictions on this.

[0035] Step 2: By analyzing the amplitude variation of the leakage current on the transmission line in the frequency domain, the high-frequency harmonic interference degree at each sampling time is obtained. Then, combined with the amplitude distribution characteristics of the leakage current harmonics in the frequency domain, the high-frequency harmonic hazard degree at each sampling time is obtained.

[0036] Because the leakage current undergoes harmonic interference changes to a certain extent when a flashover fault occurs in the insulators of transmission lines, and current technologies do not fully exploit the harmonic interference characteristics of the leakage current, the accuracy of monitoring flashover faults in transmission line insulators is poor, thus hindering timely and effective handling of these faults. Therefore, to accurately monitor flashover faults in transmission line insulators, it is necessary to fully exploit the harmonic interference characteristics of the leakage current.

[0037] To analyze the high-frequency harmonic interference characteristics of the leakage current sequence, the leakage current sequence at each acquisition time is used as the input of the Fourier transform. The Fourier transform can be either a discrete Fourier transform or a fast Fourier transform. In this embodiment, the fast Fourier transform is used for frequency domain transformation, with a preset frequency range of 0-1kHz. The resulting spectrum curve at each acquisition time reflects the frequency domain characteristics of the leakage current. The Fourier transform is a well-known technique, and the specific process will not be described in detail.

[0038] Furthermore, the frequency corresponding to the largest amplitude in the spectrum curve is calculated as the fundamental frequency of the leakage current. The amplitudes of all frequencies greater than 1 of the fundamental frequency in the spectrum curve are arranged in ascending order of frequency to obtain the harmonic amplitude sequence at each acquisition time. The harmonic amplitude sequence can reflect the harmonic abnormality characteristics during the flashover fault of the insulator of the transmission line, which is beneficial for more accurate monitoring of the flashover fault of the insulator in the future.

[0039] Under normal circumstances, if the surface of the insulator of the transmission line is clean, the leakage current on the transmission line is mainly of the power frequency. However, if the surface of the insulator of the transmission line is seriously dirty, the harmonic amplitude of the leakage current will show a more significant difference. The higher the average level of the harmonic amplitude, the higher the high-frequency harmonic interference of the leakage current caused by the dirt on the surface of the transmission line insulator, and the more likely it is to cause flashover fault of the transmission line insulator.

[0040] Based on the above analysis, the high-frequency harmonic interference level at each acquisition time is calculated:

[0041] In the formula, Let be the high-frequency harmonic interference at the t-th acquisition time. Let be the mean of the harmonic amplitude sequence at the t-th acquisition time. and Let J and (j-1) be the harmonic amplitude values ​​in the harmonic amplitude sequence at the t-th acquisition time, respectively. denoted as the number of harmonic amplitude values ​​in the harmonic amplitude sequence at the t-th acquisition time.

[0042] Among them, the high-frequency harmonic interference degree reflects the high-frequency harmonic interference characteristics of leakage current caused by contamination of the surface of insulators of transmission lines. The greater the high-frequency harmonic interference degree, the more serious the high-frequency harmonic interference of leakage current on the transmission line is, and the more likely it is to cause flashover fault of insulators of transmission lines.

[0043] Generally, flashover faults in transmission line insulators can cause serious damage to the transmission line, especially the odd-numbered harmonics generated in the leakage current. Because these odd-numbered harmonics are difficult to eliminate, their harmfulness is often greater than that caused by even-numbered harmonics. Therefore, to accurately monitor flashover faults in transmission line insulators, this embodiment uses the characteristics of high-frequency harmonic interference in the leakage current, combined with the distribution of harmonic amplitudes, to accurately measure the hazard of high-frequency harmonics in the leakage current.

[0044] Based on the above analysis, the high-frequency harmonic hazard level at each acquisition time is calculated:

[0045] In the formula, Let represent the high-frequency harmonic hazard level at the i-th acquisition time. Let be the mean of the amplitudes corresponding to all odd multiples of the fundamental frequency in the harmonic amplitude sequence at time i. Let be the mean value of the amplitudes corresponding to all even-number multiples of the fundamental frequency in the harmonic amplitude sequence at the i-th acquisition time. To avoid constants with numerators and denominators of fractions being zero, values ​​are taken within a small data range (0.01, 0.1), where the impact on the calculation results is small and negligible. In this embodiment, the value is 0.05.

[0046] Among them, the high-frequency harmonic hazard degree reflects the degree of harm caused by insulator flashover faults to transmission lines by high-frequency harmonics. The greater the high-frequency harmonic hazard degree, the higher the degree of harm caused by high-frequency harmonics in the leakage current. At this time, the transmission line is more likely to experience insulator flashover faults, affecting the safe and reliable operation of the power system. It is necessary to deal with insulator flashover faults of transmission lines in a timely and effective manner.

[0047] Step 3: Based on the degree of peak variation and the frequency of peak occurrence in the leakage current data on the transmission line, obtain the pulse anomaly degree at each acquisition time. Combined with the high-frequency harmonic hazard degree, obtain the pollution flashover fault characteristic value at each acquisition time.

[0048] In the time domain of leakage current, the peak value and frequency of the leakage current continuously increase before a flashover fault occurs in the transmission line insulator, until the insulator experiences a flashover fault. Therefore, to more accurately monitor flashover faults in transmission line insulators, this embodiment extracts features of flashover faults in transmission line insulators based on the severity of high-frequency harmonics extracted from frequency domain features, combined with the characteristics of current pulse anomalies in the time domain.

[0049] Furthermore, the leakage current sequence at each acquisition moment is used as the input of the AMPD (Asymmetric Maximum Peak Detection) algorithm. The AMPD algorithm is used to detect peaks in the leakage current sequence, obtaining all peaks in the leakage current sequence. The order of all peaks in the leakage current sequence is then calculated. The greater the increase in the peaks in the leakage current and the smaller the distance between the peaks in the leakage current sequence, the more it reflects the characteristics of the pulse peak and the continuously increasing pulse frequency of the leakage current. At this time, the leakage current exhibits abnormal current pulse characteristics. The AMPD peak detection algorithm is a well-known technology, and the specific process will not be described in detail.

[0050] Based on the above analysis, the pulse anomaly degree at each acquisition time is calculated:

[0051] In the formula, Let be the pulse anomaly degree at the t-th acquisition time. Let be the number of peak values ​​in the leakage current sequence at the t-th acquisition time. The sigmoid normalization function. and These are the i-th and (i-1)-th peak values ​​in the leakage current sequence at the t-th acquisition time, respectively. and These are the positional values ​​of the i-th and (i-1)-th peak values ​​in the leakage current sequence at the t-th acquisition time, respectively.

[0052] Among them, the pulse anomaly degree reflects the pulse anomaly change of leakage current before the occurrence of insulator flashover fault. The larger the pulse anomaly degree, the greater the current pulse anomaly change of leakage current in the time domain space. At this time, the transmission line is more likely to have an insulator flashover fault, which will affect the safe and reliable operation of the power system.

[0053] Furthermore, based on the analysis results of the leakage current in the time-frequency domain, combined with the hazard level of high-frequency harmonics in the leakage current and the abnormal characteristics of the current pulse, feature extraction is performed on the insulator flashover fault on the transmission line. Preferably, in this embodiment, the high-frequency harmonic hazard level and pulse anomaly level at all acquisition times are respectively normalized by range processing. The sum of the normalized range results of the high-frequency harmonic hazard level and pulse anomaly level at each acquisition time is recorded as the flashover fault feature value at each acquisition time, which is used to reflect the leakage current fault characteristics when the transmission line insulator flashover occurs. When the transmission line insulator flashover fault occurs, it will cause high-frequency harmonic hazards and abnormal changes in current pulses. The larger the flashover fault feature value, the more likely the insulator flashover fault will occur on the transmission line, and the more timely and effective the handling of the transmission line insulator flashover fault needs to be.

[0054] Step 4: Monitor flashover faults in transmission line insulators based on the aforementioned flashover fault characteristic values.

[0055] To address flashover faults in transmission line insulators in a timely and effective manner, this embodiment performs accurate real-time monitoring of these faults. Preferably, in this embodiment, the flashover fault feature values ​​calculated in real-time within the current acquisition time and the previous second are used as input to the LOF (Local Outlier Factor) anomaly detection algorithm. The algorithm has a preset neighborhood parameter of 12. The LOF anomaly detection algorithm obtains the anomaly detection results of flashover fault features within a short period prior to the current acquisition time. The LOF anomaly detection algorithm is a well-known technology, and its specific process will not be elaborated further.

[0056] By utilizing the LOF anomaly detection algorithm to monitor insulator flashover faults on transmission lines in real time, if the flashover fault characteristic value at the current acquisition time is abnormal data, it indicates that the flashover fault characteristics on the transmission line at this time are significantly different from those on the transmission line one second ago, indicating that an insulator flashover fault has occurred on the transmission line. In this case, it is necessary to handle the insulator flashover fault on the transmission line in a timely and effective manner to avoid causing large-scale power outages and affecting the safe and reliable operation of the power system. Conversely, if the flashover fault characteristic value at the current acquisition time is not abnormal data, it indicates that the flashover fault characteristics on the transmission line at this time are only slightly different from those on the transmission line one second ago, indicating that no insulator flashover fault has occurred on the transmission line at this time.

[0057] Based on the same inventive concept as the above method, this application embodiment also provides an insulator flashover fault monitoring system, 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 insulator flashover fault monitoring methods.

[0058] Meanwhile, this application also provides an insulator flashover fault monitoring device, which stores a computer program. When the computer program is executed by a processor, it implements any of the above-described insulator flashover fault monitoring methods.

[0059] It is understood that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0060] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0061] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Any equivalent structural or procedural transformations made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for monitoring pollution flashover failure of an insulator, characterized by, The method comprises the following steps: obtaining leakage current data of a power transmission line; obtaining high-frequency harmonic interference degrees of each collection time by analyzing the amplitude variation of the leakage current on the power transmission line corresponding to the frequency in the frequency domain, and then obtaining high-frequency harmonic hazard degrees of each collection time in combination with the amplitude distribution characteristics of the harmonics in the frequency domain; arranging the leakage current data in a preset time length before each collection time in chronological order to form a leakage current sequence of each collection time, performing frequency domain transformation on the leakage current sequence, arranging all the amplitudes corresponding to the integer multiples greater than 1 of the fundamental frequency in the frequency spectrum curve diagram in ascending order of frequency to form a harmonic amplitude sequence of each collection time; obtaining pulse abnormality degrees of each collection time according to the peak value variation degree and the peak value occurrence frequency in the leakage current data on the power transmission line, and obtaining pollution flashover fault characteristic values of each collection time in combination with the high-frequency harmonic hazard degrees; monitoring the pollution flashover fault of the insulator of the power transmission line based on the pollution flashover fault characteristic values; the obtaining of the high-frequency harmonic interference degrees of each collection time further comprises: wherein, is the high-frequency harmonic interference degree at the tth acquisition time, is the mean value of the harmonic amplitude sequence at the tth acquisition time, and are the jth and the j-1th amplitudes in the harmonic amplitude sequence at the tth acquisition time, respectively, is the number of amplitudes in the harmonic amplitude sequence at the tth acquisition time. the obtaining of the high-frequency harmonic hazard degrees of each collection time further comprises: wherein, is the high-frequency harmonic hazard at the tth acquisition time, is the high-frequency harmonic interference at the tth acquisition time, is the mean of all odd multiple of fundamental frequency corresponding amplitude in the harmonic amplitude sequence at the tth acquisition time, is the mean of all even multiple of fundamental frequency corresponding amplitude in the harmonic amplitude sequence at the tth acquisition time, is a constant to avoid the numerator and denominator of the fraction being 0; the obtaining of the pulse abnormality degrees of each collection time further comprises: wherein, is the pulse abnormality at the t-th acquisition time, is the number of peaks in the leakage current sequence at the t-th acquisition time, is a sigmoid normalization function, and are the i-th and i-1-th peaks in the leakage current sequence at the t-th acquisition time, respectively, and are the bit sequences of the i-th and i-1-th peaks in the leakage current sequence at the t-th acquisition time, respectively.

2. The method of monitoring pollution flashover failure of an insulator according to claim 1, wherein performing peak value detection on the leakage current sequence of each collection time to extract all the peak values in the leakage current sequence, and counting the bit sequence of all the peak values in the leakage current sequence.

3. The method of monitoring pollution flashover failure of an insulator according to claim 1, wherein The pollution flashover fault characteristic value of each collection time is the sum of the normalized result of the high-frequency harmonic hazard degree and the normalized result of the pulse abnormality degree of each collection time.

4. The method of claim 1, wherein the step of monitoring the pollution flashover failure of the insulator is characterized by, performing anomaly detection on all the pollution flashover fault characteristic values in a preset time length before the current collection time, and if the pollution flashover fault characteristic value of the current collection time is abnormal data, it indicates that the insulator of the power transmission line has a pollution flashover fault, otherwise, the insulator of the power transmission line does not have a pollution flashover fault.

5. An insulator pollution flashover failure monitoring system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, The processor executes the computer program to realize the steps of the insulator pollution flashover fault monitoring method according to any one of claims 1-4.

6. An insulator pollution flashover failure monitoring device, a computer program is stored in the device, characterized in that, The computer program is executed by the processor to realize the insulator pollution flashover fault monitoring method according to any one of claims 1-4.

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