An intelligent SPD lightning protection detection system

Abstract

The present invention relates to the field of SPD lightning protection technology, and specifically to an intelligent SPD lightning protection detection system. The system includes: a data acquisition module for obtaining the leakage current, voltage and temperature of a varistor; a lightning protection analysis module for analyzing the discrete degree of the leakage current of the varistor and the leakage current change trend, and combining the temperature extremes of the varistor and the discrete degree of all elements in the leakage current coupling sequence to determine the damage degree of the varistor; by analyzing the complexity of the mutation data in the varistor voltage and the voltage change trend, and combining the similarity of the voltage change trend between parallel varistors, the voltage anomaly of the varistor is determined; a lightning protection detection module for judging the lightning protection detection accuracy at the current moment. This application solves the problem that the SPD lightning protection detection system cannot avoid the damage to electrical equipment caused by lightning surges and power frequency voltage, and improves the reliability of the SPD lightning protection detection system.

Description

Technical Field

[0001] The present invention relates to the technical field of SPD lightning protection, and in particular to an intelligent SPD lightning protection detection system. Background Art

[0002] SPD (Surge Protective Device), also known as a surge protector, and the intelligent SPD lightning protection detection system are a surge protection device monitoring system that integrates the Internet of Things, edge computing, and artificial intelligence technologies. Based on the surge discharge function of traditional SPDs, it uses embedded sensors and intelligent algorithms to achieve real-time monitoring, early warning, and data analysis of lightning activity, equipment status, and environmental parameters, promoting the development and progress of lightning protection systems from "passive protection" to a combination of active prediction and adaptive protection.

[0003] In an SPD lightning protection detection system, the core function of the varistor is to protect electrical equipment from damage caused by lightning surge current. Its stable electrical characteristics also ensure that the entire lightning protection system can effectively protect electrical equipment during long-term use. However, the SPD lightning protection detection system operates under power frequency voltage for a long time and is constantly subjected to overvoltage shocks. Under repeated overvoltage shocks, the varistor will suffer grain damage and accelerated grain boundary degradation, resulting in a gradual increase in leakage current, an aggravated temperature rise, and a corresponding change in voltage. As a result, the SPD lightning protection detection system cannot effectively prevent lightning surge damage to electrical equipment during a lightning strike, reducing the reliability of the SPD lightning protection detection system. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide an intelligent SPD lightning protection detection system, and the technical solutions adopted are as follows:

[0005] The present invention proposes an intelligent SPD lightning protection detection system, which includes:

[0006] Data acquisition module, used to obtain the leakage current, voltage and temperature of each varistor in real time during the SPD lightning protection detection process;

[0007] The lightning protection analysis module is used to number the leakage current peaks and temperature peaks of each varistor at all times within a preset time period before the current moment, and compare the differences between all leakage current peaks and temperature peaks with the same number to construct a leakage current-temperature coupling sequence for each varistor at the current moment;

[0008] Within the preset time period, the discrete degree of leakage current of each varistor at all times and the difference in leakage current between all adjacent times are analyzed to determine the leakage current fluctuation of each varistor at the current moment; by calculating the temperature extreme difference of each varistor and the discrete degree of all elements in the leakage current coupling sequence within the preset time period before the current moment, the leakage current coupling abnormality of each varistor at the current moment is determined, and combined with the leakage current fluctuation, the damage degree of each varistor at the current moment is determined;

[0009] Within the preset time length, by analyzing the complexity of the mutation data in the voltage of each varistor at all times and the difference in voltage between all adjacent moments, the voltage attenuation jump degree of each varistor at the current moment is determined; within the preset time length, based on the similarity of all voltage change trends between each varistor and each varistor connected in parallel with it, the voltage consistency of each varistor at the current moment is determined, and combined with the voltage attenuation jump degree, the voltage anomaly of each varistor at the current moment is determined;

[0010] The lightning protection detection module is used to determine the degradation factor of each varistor at the current moment based on the damage degree and the voltage abnormality, so as to judge the lightning protection detection accuracy at the current moment.

[0011] Preferably, the step of constructing the leakage current-temperature coupling sequence of each varistor at the current moment includes:

[0012] The ratios between all leakage current peaks and temperature peaks with the same number for each varistor within a preset time period before the current moment are calculated, and all the ratios are combined into a leakage current coupling sequence for each varistor at the current moment.

[0013] Preferably, the leakage current fluctuation of each varistor at the current moment is: the result of the positive fusion of the cumulative result of the leakage current difference between all adjacent moments of each varistor within a preset time period before the current moment and the leakage current discrete degree at all moments.

[0014] Preferably, the leakage current coupling abnormality of each varistor at the current moment is: the result of dividing the temperature extreme difference of each varistor within a preset time period before the current moment by the discrete degree of all elements in the leakage current coupling sequence.

[0015] Preferably, the damage degree of each varistor at the current moment is a normalized value of the multiplication result of the leakage current fluctuation degree and the leakage current coupling anomaly degree of each varistor at the current moment.

[0016] Preferably, the expression of the voltage attenuation jump degree of each varistor at the current moment is: Where, Indicates the voltage attenuation jump degree of varistor i at the current moment; Represents the cumulative sum of all elements in the first-order difference sequence of the voltage of varistor i at all times within a preset time period before the current moment; The Hurst index represents the sudden change data of the voltage of the varistor i at all times within the preset time period before the current moment; Represents the preset adjustment parameter; exp( ) represents the exponential function with a natural constant as the base.

[0017] Preferably, the method for determining the voltage consistency of each varistor at the current moment is:

[0018] The similarity of the first-order difference sequence of the voltage between each varistor and each varistor connected in parallel with it at all times is calculated, and the cumulative sum of the similarities between each varistor and all the varistors connected in parallel with it is used as the voltage consistency of each varistor at the current moment.

[0019] Preferably, the voltage anomaly degree of each varistor at the current moment is the ratio of the voltage attenuation jump degree to the voltage consistency degree of each varistor at the current moment.

[0020] Preferably, the degradation factor of each varistor at the current moment is a normalized value of the product of the damage degree of each varistor and the voltage abnormality degree at the current moment.

[0021] Preferably, the determining of the lightning protection detection accuracy at the current moment includes:

[0022] If the degradation factor of any varistor at the current moment is greater than or equal to the preset degradation threshold, the SPD lightning protection detection accuracy at the current moment is unqualified; otherwise, the SPD lightning protection detection accuracy at the current moment is qualified.

[0023] The present invention has the following beneficial effects:

[0024] This application first constructs the damage degree of the varistor by monitoring the leakage current fluctuation degree of the varistor and the degree of abnormal coupling between the leakage current and temperature, and effectively evaluates the degree of grain boundary damage of the varistor, which helps to timely discover potential faults and improve the reliability and safety of the lightning protection system; further, this application constructs the voltage anomaly degree by introducing two key indicators, voltage attenuation jump degree and voltage consistency, which makes up for the shortcomings of relying solely on leakage current and temperature coupling analysis. It not only quantitatively analyzes the mutation complexity and variation amplitude of the voltage of a single varistor, but also evaluates the similarity of the voltage change trend between parallel varistors, and judges the voltage anomaly degree accordingly, so as to more comprehensively capture the damage of the varistor due to grain boundary damage under the action of lightning surge and power frequency voltage. The voltage characteristic degradation caused by melting, uneven damage, etc., especially the identification of unbalanced working problems in parallel structures, improves the accuracy of judging the degree of SPD degradation and aging by comprehensively evaluating multi-dimensional information such as voltage and leakage current, which helps to give early warning of potential faults and ensure the reliable operation of the lightning protection system; further, the present application comprehensively considers the damage degree and voltage abnormality to determine the degradation factor of the varistor, which is used to judge the overall degradation degree of the SPD and the lightning protection detection accuracy, which can overcome the shortcomings of traditional detection methods, and realize accurate early warning of the internal state of the SPD, especially grain boundary damage and voltage degradation, ensuring that the SPD lightning protection system can effectively protect electrical equipment when a lightning strike occurs, thereby improving the reliability of the SPD lightning protection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A block diagram of an intelligent SPD lightning protection detection system provided in one embodiment of the present application;

[0027] Figure 2 A schematic diagram of the degradation factor extraction process provided in one embodiment of the present application. DETAILED DESCRIPTION

[0028] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of an intelligent SPD lightning protection detection system proposed in accordance with the present invention. In the following description, references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0029] Unless defined otherwise, 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 invention belongs.

[0030] The specific solution of an intelligent SPD lightning protection detection system provided by the present invention is described in detail below with reference to the accompanying drawings.

[0031] See also Figure 1 , which shows a block diagram of an intelligent SPD lightning protection detection system provided by an embodiment of the present invention. The system includes: a data acquisition module 101, a lightning protection analysis module 102, and a lightning protection detection module 103.

[0032] The data acquisition module 101 is used to obtain the leakage current, voltage and temperature of each varistor in real time during the SPD lightning protection detection process.

[0033] In this embodiment, a zero-flux current sensor, a high-voltage differential probe, and a thermocouple are deployed in the intelligent SPD lightning protection detection system to respectively collect the leakage current, voltage, and temperature of each metal oxide (MOV) varistor in the intelligent SPD lightning protection detection system in real time through the zero-flux current sensor, the high-voltage differential probe, and the thermocouple. For ease of description, the metal oxide varistor is simply referred to as a varistor. Furthermore, the leakage current, voltage, and temperature are synchronously collected, and the collection frequency is f.

[0034] It should be noted that the data acquisition frequency f is manually set. In this embodiment, the data acquisition frequency f is 256 Hz. In actual application, as other implementation methods, the implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

[0035] Furthermore, in order to prevent the external environment interference from causing information loss during the collection process of the above data and the different impacts of different data dimensions, this embodiment uses the median filling method to fill the various types of data collected above. In actual application, as other implementation methods, the implementer can also use other filling methods such as the mean filling method based on the specific situation. Regarding the selection of filling method, this embodiment does not impose any special restrictions.

[0036] Among them, the median filling method is a well-known technology, that is, the median of a set of data is used as the value of the missing value position. The specific process of using the median filling method to fill the missing value will not be described in detail.

[0037] In addition, in order to prevent the influence of data dimension, this embodiment normalizes each type of data after the above-mentioned median filling. In this embodiment, the data normalization method adopts the z-score normalization method. In the actual application process, as other implementation methods, the implementer can also adopt other methods such as maximum and minimum value normalization method according to the specific situation. Regarding the selection of normalization method, this embodiment does not impose any special restrictions.

[0038] Among them, the z-score normalization method is a well-known technology, and the specific process of using it to normalize the data will not be described in detail.

[0039] It is additionally noted that, unless otherwise specified, all contents involving normalization processing or calculation in this embodiment adopt the z-score normalization method.

[0040] The lightning protection analysis module 102 is used to determine the voltage anomaly degree of each varistor.

[0041] S1: Number the leakage current peaks in the leakage current and the temperature peaks in the temperature of each varistor at all moments within a preset time period before the current moment respectively according to the time sequence, compare the differences between all leakage current peaks and temperature peaks with the same numbers, so as to construct a leakage current-temperature coupling sequence of each varistor at the current moment; within the preset time period, analyze the discrete degree of the leakage current of each varistor at all moments and the difference in leakage current between all adjacent moments to determine the leakage current fluctuation of each varistor at the current moment; determine the leakage current coupling anomaly of each varistor at the current moment by calculating the temperature extreme difference of each varistor within the preset time period before the current moment and the discrete degree of all elements in the leakage current coupling sequence, and determine the damage degree of each varistor at the current moment in combination with the leakage current fluctuation.

[0042] During the operation of the intelligent SPD lightning protection detection system, lightning surge impact or long-term power frequency voltage will cause irreversible damage to the grain boundary barrier potential of the varistor, and accelerate the degradation and aging of the voltage. After the varistor is subjected to lightning surge or power frequency current impact, the grains in the grain boundary layer of the varistor are crushed and have higher resistance. The heat accumulation effect caused by the temperature increase will further weaken the barrier potential of the grain boundary layer of the varistor, thereby increasing the leakage current.

[0043] Specifically, the more severe the degradation and aging condition of the varistor under lightning surge impact or long-term power frequency voltage, the more obvious fluctuations in the leakage current will be caused by the random enhancement of ion migration due to grain boundary breakdown of the varistor, and the nonlinear growth of the leakage current over time will be more severe due to the damage to the grain boundaries of the varistor and the increased probability of electron tunneling. At the same time, according to Joule's law, the more consistent the change trend of the coupling effect of the synchronous growth of temperature and leakage current caused by the comminuted destruction of the grain boundary structure of the varistor, the higher the degree of temperature growth.

[0044] Based on the above analysis, this embodiment determines the leakage current fluctuation of each varistor at the current moment by analyzing the discrete degree of the leakage current of each varistor at all times within the preset time length before the current moment and the difference in leakage current between all adjacent moments; by calculating the temperature extreme difference of each varistor within the preset time length before the current moment and the discrete degree of all elements in the leakage current coupling sequence, the leakage current coupling abnormality of each varistor at the current moment is determined, and combined with the leakage current fluctuation, the damage degree of each varistor at the current moment is determined, specifically:

[0045] First, this embodiment uses the leakage current and temperature of each varistor at all times within a preset time period before the current moment as inputs to an Automatic Multiscale-based Peak Detection (AMPD) algorithm, and outputs all leakage current peaks of the leakage current and all temperature peaks of the temperature, and numbers all leakage current peaks and all temperature peaks in chronological order. Furthermore, this embodiment compares the differences between all leakage current peaks and temperature peaks with the same number to construct a leakage current-temperature coupling sequence of each varistor at the current moment. Specifically: in this embodiment, the ratio between all leakage current peaks and temperature peaks with the same number of each varistor within the preset time period before the current moment is calculated, and all the ratios are combined into a leakage current coupling sequence of each varistor at the current moment.

[0046] It should be noted that the value of the preset time length is set manually. In this embodiment, the value of the preset time length is 30s. In actual application, as other implementation methods, the implementer can also set it by himself based on the specific situation. This embodiment does not impose any special restrictions.

[0047] Among them, the multi-scale peak detection algorithm is a well-known technology, and the specific process of using it to extract a group of data peaks will not be described in detail.

[0048] Furthermore, this embodiment determines the leakage current fluctuation of each varistor at the current moment by analyzing the discrete degree of the leakage current of each varistor at all moments and the difference of the leakage current between all adjacent moments, specifically:

[0049] In this embodiment, the cumulative result of the leakage current differences between all adjacent moments of each varistor within a preset time period before the current moment and the forward fusion result of the leakage current discreteness at all moments are used as the leakage current fluctuation of each varistor at the current moment.

[0050] It should be understood that forward fusion refers to combining two or more indicators through addition or multiplication to obtain a comprehensive indicator, thereby more comprehensively and accurately evaluating a phenomenon or problem. This fusion method is not limited to simple arithmetic operations and can also include more complex statistical models and analysis methods. Implementers can choose according to their specific circumstances and this embodiment does not impose any special restrictions.

[0051] Preferably, as an implementation method, in this embodiment, the leakage current fluctuation of the varistor i at the current moment is The expression is: Where, Indicates the standard deviation of the leakage current of varistor i at all times within the preset time period before the current moment; represents the cumulative sum of the absolute values ​​of the leakage current differences between all adjacent moments of varistor i within a preset time period before the current moment; exp( ) represents an exponential function with a natural constant as the base, which traverses all varistors to obtain the leakage current fluctuation of each varistor at the current moment.

[0052] It should be noted that there are many methods for measuring the degree of discreteness of a set of data and the differences between data. In this embodiment, the standard deviation of the leakage current of the varistor i at all moments within the preset time length before the current moment is used as the discreteness of the leakage current of the varistor i at all moments within the preset time length before the current moment, and the cumulative sum of the absolute values ​​of the leakage current differences between all adjacent moments of the varistor i within the preset time length before the current moment is used as the cumulative sum of the leakage current differences between all moments of the varistor i within the preset time length before the current moment. In actual application, the implementer may also adopt other methods for measuring the degree of discreteness of data, such as variance or dispersion coefficient, in combination with specific circumstances, or may adopt other methods for measuring the differences between data, such as the square or ratio of the difference, in combination with specific circumstances. The methods for measuring the degree of discreteness of a set of data and the selection of methods for measuring the differences between data will not be repeated here.

[0053] Furthermore, according to the leakage current fluctuation of each varistor at the current moment, it can be understood that the leakage current fluctuation is used to characterize the complexity and irregularity of the leakage current changing over time. If the standard deviation of the leakage current of the varistor i at all moments in the preset time period before the current moment is larger, it means that the leakage current fluctuation amplitude of the varistor i is larger, that is, the leakage current fluctuates more violently in the preset time period before the current moment, and the stability is poor. Therefore, the corresponding leakage current fluctuation is correspondingly larger; at the same time, if the cumulative sum of the absolute values ​​of the leakage current differences between all adjacent moments of the varistor i in the preset time period before the current moment is larger, it means that the leakage current of the varistor i deviates more seriously from its linear growth trend, that is, the nonlinear growth characteristics of the leakage current over time are more obvious, and its change trend is more irregular. Therefore, the corresponding leakage current fluctuation is correspondingly larger.

[0054] On the contrary, if the standard deviation of the leakage current of the varistor i at all moments within the preset time length before the current moment is smaller, it means that the leakage current fluctuation amplitude of the varistor i is smaller, that is, the leakage current fluctuates more gently within the preset time length before the current moment, and the stability is better. Therefore, the corresponding leakage current fluctuation is correspondingly smaller; at the same time, if the cumulative sum of the absolute values ​​of the leakage current differences between all adjacent moments of the varistor i within the preset time length before the current moment is smaller, it means that the degree to which the leakage current of the varistor i deviates from its linear growth trend is more slight, that is, the nonlinear growth characteristics of the leakage current over time are less obvious, and its change trend is more regular. Therefore, the corresponding leakage current fluctuation is correspondingly smaller.

[0055] Furthermore, this embodiment determines the leakage current coupling anomaly degree of each varistor at the current moment by calculating the temperature extreme difference of each varistor within a preset time period before the current moment and the discrete degree of all elements in the leakage current coupling sequence, specifically:

[0056] In this embodiment, the temperature extreme difference of each varistor within a preset time period before the current moment is divided by the discrete degree of all elements in the leakage current coupling sequence to serve as the leakage current coupling abnormality degree of each varistor at the current moment.

[0057] It should be noted that there are many methods for measuring the degree of discreteness of a set of data. In this embodiment, the discrete coefficient of all elements in the leakage current coupling sequence is used as the discreteness of all elements in the leakage current coupling sequence. In actual application, the implementer may also use other methods such as standard deviation or variance to measure the discreteness of a set of data based on specific circumstances. This embodiment does not impose any special restrictions.

[0058] The calculation process of the dispersion coefficient is a well-known technology, and its specific calculation process will not be repeated here.

[0059] According to the leakage current coupling anomaly of each varistor at the current moment, it can be understood that the leakage current coupling anomaly reflects the instability of the temperature growth and leakage current-temperature coupling change trend caused by grain boundary damage of the varistor. If the temperature range of the current varistor is larger within the preset time period before the current moment, it means that the temperature fluctuation range of the current varistor is larger and the temperature growth is more significant. According to Joule's law, this usually means that the leakage current is larger or more unstable, resulting in more severe heating, indicating that the instability of the temperature growth and leakage current-temperature coupling change trend caused by grain boundary damage of the varistor is greater, indicating that the SPD lightning protection detection system is subjected to a lightning surge or long-term power frequency voltage at this time; at the same time, if the discrete degree of all elements in the leakage current-temperature coupling sequence of the current varistor within the preset time period before the current moment is smaller, and the temperature change range is larger, it means that the leakage current change range is smaller. Under normal circumstances, the leakage current and temperature change trends are consistent. Therefore, the possibility of an abnormality in the coupling between the leakage current and temperature is more serious, that is, the corresponding leakage current coupling anomaly is greater.

[0060] Furthermore, this embodiment determines the voltage anomaly degree of each varistor at the current moment based on the voltage consistency and voltage attenuation jump degree of each varistor at the current moment, specifically:

[0061] As a specific implementation, in this embodiment, the normalized value of the multiplication result of the leakage current fluctuation degree and the leakage current coupling abnormality degree of each varistor at the current moment is used as the damage degree of each varistor at the current moment.

[0062] According to the damage degree of each varistor at the current moment, it can be understood that the damage degree is used to characterize the degree of grain boundary damage caused by lightning surge and power frequency voltage to the varistor. The closer the damage degree is to 1, the more serious the grain boundary damage is. If the damage degree of the varistor is closer to 0, the grain boundary damage is milder. If the leakage current fluctuation degree of each varistor at the current moment is greater, it means that the nonlinear fluctuation of the leakage current of the varistor is stronger, that is, the leakage current fluctuates violently and the nonlinear trend is obvious, indicating that the grain boundary damage is more serious, and therefore, the corresponding damage degree is greater. At the same time, if the leakage current coupling anomaly of the current varistor at the current moment is greater, that is, the anomaly of the coupling between the leakage current of the varistor and the temperature is stronger, it means that the temperature fluctuation is large and the coupling of the remaining leakage current is unstable, which means that the grain boundary damage is more serious and the grain boundary is more damaged by the lightning surge impact or long-term power frequency voltage.

[0063] On the contrary, if the leakage current fluctuation of each varistor at the current moment is smaller, it means that the nonlinear fluctuation of the leakage current of the varistor is weaker, that is, the leakage current fluctuation is smooth and the linear trend is obvious, indicating that its grain boundary damage is milder, and therefore, the corresponding damage degree is smaller; at the same time, if the leakage current of the varistor is less abnormally coupled with temperature, that is, the temperature fluctuation is small and the coupling with the leakage current is more stable, it indicates that its grain boundary damage is milder, and the grain boundary is less damaged by lightning surge impact or long-term power frequency voltage.

[0064] Thus, this embodiment has established the damage degree of the varistor by monitoring the leakage current fluctuation degree of the varistor and the abnormal coupling degree of the leakage current and temperature, and effectively evaluated the grain boundary damage degree of the varistor, thereby helping to timely detect potential faults and improve the reliability and safety of the lightning protection system.

[0065] S2: Within the preset time length, by analyzing the complexity of the mutation data in the voltage of each varistor at all times and the difference in voltage between all adjacent moments, the voltage attenuation jump degree of each varistor at the current moment is determined; within the preset time length, based on the similarity of all voltage change trends between each varistor and each varistor connected in parallel with it, the voltage consistency of each varistor at the current moment is determined, and combined with the voltage attenuation jump degree, the voltage abnormality of each varistor at the current moment is determined.

[0066] During the operation of the intelligent SPD lightning protection detection system, the varistor will also cause the grain boundaries to melt and bond under the action of lightning surge and power frequency voltage, forming larger grain clusters, exacerbating the uneven damage of the grain boundary barrier potential. There are still certain disadvantages in evaluating the degree of degradation and aging of the varistor based solely on the abnormal leakage current of the varistor and the leakage current-temperature coupling change characteristics. That is, it does not take into account the abnormal changes in the voltage of the varistor caused by internal damage due to the impact of lightning surge and power frequency voltage. There is a lack of coordinated analysis of multiple parallel varistors in the SPD lightning protection detection system, resulting in inaccurate assessment of the degradation and aging degree of the varistor, which in turn affects the normal operation of the SPD lightning protection detection system.

[0067] Specifically, in the SPD lightning protection detection system, the stronger the aging degradation of the varistor, the stronger the voltage drop trend caused by grain boundary fusion and bonding, and the voltage jump is significantly irregular due to the influence of the micro-short-circuit channel formed by grain boundary breakdown. At the same time, the aging degradation of the varistor will also seriously affect the consistency of the parallel structure of the varistor in the SPD lightning protection detection system, and the voltage change degree of different varistors is significantly inconsistent.

[0068] Based on the above analysis, this embodiment determines the voltage attenuation jump degree of each varistor at the current moment by analyzing the complexity of the mutation data in the voltage of each varistor at all times and the difference in voltage between all adjacent moments; within the preset time length, based on the similarity of all voltage change trends between each varistor and each varistor connected in parallel with it, the voltage consistency of each varistor at the current moment is determined, and combined with the voltage attenuation jump degree, the voltage anomaly of each varistor at the current moment is determined, which is used to characterize the voltage anomaly caused by grain boundary barrier potential damage caused by lightning surge impact and power frequency voltage in the test interval. The specific process is as follows:

[0069] In this embodiment, first, by analyzing the complexity of the mutation data in the voltage of each varistor at all times and the difference in voltage between all adjacent moments, the voltage attenuation jump degree of each varistor at the current moment is determined, specifically:

[0070] As a specific implementation, in this embodiment, the expression of the voltage attenuation jump degree of each varistor at the current moment is: Where, Indicates the voltage attenuation jump degree of varistor i at the current moment; Represents the cumulative sum of all elements in the first-order difference sequence of the voltage of varistor i at all times within a preset time period before the current moment; The Hurst index represents the sudden change data of the voltage of the varistor i at all times within the preset time period before the current moment; Represents the preset adjustment parameter; exp( ) represents the exponential function with a natural constant as the base.

[0071] It should be noted that the value of the preset adjustment parameter is set manually. In this embodiment, the value of the preset adjustment parameter is 0.5. In actual application, as other implementation methods, the implementer can also set it by himself based on the specific situation. This embodiment does not impose any special restrictions.

[0072] The calculation method of the Hurst index is a well-known technique, and its specific calculation process will not be described in detail.

[0073] According to the voltage attenuation jump degree of each varistor at the current moment, it can be understood that the voltage attenuation jump degree quantifies the intensity of the voltage attenuation trend and the degree of abnormal voltage change caused by the two situations of crystallization melting bonding and micro-short circuit channel formation; if the cumulative sum of all elements in the first-order difference sequence of the voltage of the varistor i at all times within the preset time before the current moment is greater than 0 and the larger it is, the greater the voltage change amplitude between adjacent moments, indicating that the varistor is affected by internal damage, and has a more significant and rapid attenuation or jump, and the voltage stability is extremely poor, and the corresponding voltage attenuation jump degree is correspondingly larger; at the same time, if the Hurst index is greater than And with The larger the difference, the more intense and sustained the change trend of the varistor voltage is when a sudden change occurs. For example, once the voltage starts to drop, it continues to drop rather than fluctuating randomly. This means that some kind of continuous damage mechanism is at work, causing the voltage of the varistor i to continue to decay. Therefore, the corresponding voltage decay jump is larger.

[0074] On the contrary, if the cumulative sum of all elements in the first-order difference sequence of the voltage of the varistor i at all times within the preset time period before the current moment is less than or equal to 0, the smaller the voltage change amplitude between adjacent moments is, indicating that the varistor is less affected by internal damage, the voltage change is relatively gentle, the stability is better, and the corresponding voltage attenuation jump degree is correspondingly smaller; at the same time, if the Hurst index is less than or equal to or with The smaller the phase difference, the more random and less persistent the change trend of the varistor's voltage is when a sudden change occurs. For example, a drop or rise in voltage is more likely to be a short, random fluctuation rather than a continuous change in a single direction. This means that the internal damage mechanism is relatively stable or mild, and does not lead to continuous and strong voltage attenuation. Therefore, the corresponding voltage attenuation jump is smaller.

[0075] Furthermore, this embodiment obtains a first-order differential sequence of the voltage of each varistor at all times within a preset time period before the current moment. This embodiment calculates the similarity of the first-order differential sequences of the voltages at all times between each varistor and each varistor connected in parallel with it, and uses the cumulative sum of the similarities between each varistor and all the varistors connected in parallel with it as the voltage consistency of each varistor at the current moment, which is used to characterize the consistency of the working states of the parallel varistors.

[0076] If the voltage consistency of the current varistor is greater, it means that the voltage change rate between the current varistor and the varistor connected in parallel is more similar, indicating that the working state between the current varistor and the varistor connected in parallel is more consistent, indicating that the current varistor is less likely to be affected by aging and degradation; conversely, if the voltage consistency of the current varistor is smaller, it means that the voltage change rate difference between the current varistor and the varistor connected in parallel is greater, indicating that the working state difference between the current varistor and the varistor connected in parallel is greater, indicating that the current varistor is more likely to be affected by aging and degradation.

[0077] It should be noted that there are many methods for measuring the similarity between sequences. In this embodiment, the cosine similarity of the first-order difference sequence of the voltage between each varistor and each varistor connected in parallel with it at all times is used as the similarity of the first-order difference sequence of the voltage between each varistor and each varistor connected in parallel with it at all times. In actual application, as other real-time methods, the implementer may also adopt other methods for measuring the similarity between sequences, such as the inverse of the DTW distance, based on specific circumstances. This embodiment does not impose any special restrictions on the selection of methods for measuring the similarity between sequences.

[0078] The calculation method of cosine similarity is a well-known technology, and its specific calculation process will not be described in detail.

[0079] Furthermore, this embodiment determines the voltage anomaly of each varistor at the current moment based on the voltage consistency of each varistor at the current moment and in combination with the voltage attenuation jump degree, specifically:

[0080] In this embodiment, the ratio of the voltage attenuation jump degree to the voltage consistency of each varistor at the current moment is used as the voltage anomaly degree of each varistor at the current moment.

[0081] According to the voltage anomaly of each varistor at the current moment, it can be understood that the voltage anomaly is used to judge the degree of abnormality of the voltage characteristic of the varistor. If the voltage attenuation jump degree of the current varistor is larger, it means that the voltage of the current varistor itself has a more serious irregular attenuation jump, and the abnormality of its voltage characteristic will increase. Therefore, the corresponding voltage anomaly is larger; at the same time, if the voltage consistency of the current varistor is smaller, it means that the current varistor itself may have attenuation or jump, and the voltage change rate between the current varistor and the varistor in parallel is very different, which makes the voltage anomaly significantly increase. The larger the corresponding voltage anomaly is, it indicates that the current varistor has serious abnormality and imbalance.

[0082] On the contrary, if the voltage attenuation jump degree of the current varistor is smaller, it means that the voltage of the current varistor itself changes more slowly and regularly, and the abnormality of its voltage characteristics will be reduced. Therefore, the corresponding voltage abnormality is smaller; at the same time, if the voltage consistency of the current varistor is greater, it means that the voltage of the current varistor itself is stable, and the difference in voltage change rate between it and the parallel varistor is small, the overall working state is more balanced, which significantly reduces the voltage abnormality, and the corresponding voltage abnormality is smaller; it indicates that the current varistor working state is normal and balanced.

[0083] At this point, this embodiment has constructed a voltage anomaly degree by introducing two key indicators, namely voltage attenuation jump degree and voltage consistency, to make up for the shortcomings of relying solely on leakage current and temperature coupling analysis. It not only quantitatively analyzes the mutation complexity and change amplitude of the voltage of a single varistor, but also evaluates the similarity of the voltage change trends between parallel varistors, and judges the voltage anomaly degree accordingly. This method can more comprehensively capture the voltage characteristic degradation of varistors caused by grain boundary melting, uneven damage, etc. under the action of lightning surges and power frequency voltage, especially identify the working imbalance problem in the parallel structure. By comprehensively evaluating multi-dimensional information such as voltage and leakage current, the accuracy of judging the degree of SPD degradation and aging is significantly improved, which helps to provide early warning of potential faults and ensure the reliable operation of the lightning protection system.

[0084] The lightning protection detection module 103 is configured to determine a degradation factor of each varistor at a current moment based on the damage degree and the voltage abnormality degree, so as to judge the lightning protection detection accuracy at a current moment.

[0085] Based on the damage degree and voltage anomaly degree obtained in the lightning protection analysis module, the degradation factor of each varistor at the current moment is further constructed to characterize the degree of degradation and aging of the varistor caused by lightning surge impact and power frequency voltage. Specifically, it is:

[0086] In this embodiment, a normalized value of a product of the damage degree of each varistor and the voltage abnormality degree at the current moment is used as the degradation factor of each varistor at the current moment.

[0087] Preferably, the degradation factor extraction process diagram provided in this embodiment is as follows: Figure 2 shown.

[0088] Based on the degradation factor of each varistor at the current moment, it can be understood that the greater the current damage degree of the varistor, the more serious the internal structure damage caused by the lightning surge and power frequency voltage, and the higher the overall degree of degradation and aging. At the same time, the greater the current voltage abnormality of the varistor, the more obvious the abnormality of the voltage characteristics of the varistor, and the higher the overall degree of degradation and aging. Therefore, the larger the corresponding degradation factor, the higher the overall degree of degradation of the current varistor, and the more vigilant or even replacement is needed.

[0089] Conversely, a smaller degradation factor indicates less damage to the varistor's internal structure and less degradation from lightning surges and power-frequency voltage. Furthermore, its voltage characteristics are relatively stable, with fewer anomalies. Therefore, a smaller degradation factor indicates a lower overall degradation level and a relatively healthy condition for the varistor. No special precautions or replacement are required, and the varistor can continue to operate safely.

[0090] Furthermore, this embodiment determines the lightning protection detection accuracy based on the degradation factor, specifically:

[0091] In this embodiment, if the degradation factor of any varistor at the current moment is greater than or equal to the preset degradation threshold, it means that the degree of damage to the grain boundary barrier potential of the varistor is high and the grain crushing damage is serious, which in turn affects the detection accuracy of the SPD lightning protection detection system for lightning surges. It is low and cannot effectively protect electrical equipment from accumulated surges. Therefore, the SPD lightning protection detection accuracy at the current moment is unqualified; on the contrary, if the degradation factors of all varistors at the current moment are less than the preset degradation threshold, it means that the degree of degradation and aging of the varistor caused by lightning surges and power frequency voltage at the current moment is slight. Therefore, the SPD lightning protection detection accuracy at the current moment is qualified.

[0092] It should be noted that the value of the preset degradation threshold is artificially set. In this embodiment, the value of the preset degradation threshold is 0.6. In actual application, as other implementation methods, the implementer can also set it by himself based on the specific situation. This embodiment does not impose any special restrictions.

[0093] At this point, this embodiment collects the leakage current, voltage and temperature data of the varistor in real time, and uses multiple intelligent algorithms such as multi-scale peak detection, discrete degree analysis, and Hurst index to quantitatively evaluate key indicators such as the leakage current fluctuation, leakage current-temperature coupling anomaly, voltage attenuation jump, and voltage consistency of the varistor. Based on these indicators, the damage degree and voltage anomaly are comprehensively calculated, and finally a degradation factor is formed to judge the overall degradation degree of the SPD and the lightning protection detection accuracy. It can overcome the shortcomings of traditional detection methods and achieve accurate early warning of the internal state of the SPD, especially grain boundary damage and voltage degradation, significantly improving the reliability of the lightning protection system and ensuring that it can effectively protect electrical equipment when a lightning strike occurs.

[0094] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0095] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An intelligent SPD lightning protection detection system, characterized in that: The system comprises: Data acquisition module, used to obtain the leakage current, voltage and temperature of each varistor in real time during the SPD lightning protection detection process; The lightning protection analysis module is used to number the leakage current peaks and temperature peaks of each varistor at all times within a preset time period before the current moment, and compare the differences between all leakage current peaks and temperature peaks with the same number to construct a leakage current-temperature coupling sequence for each varistor at the current moment; Within the preset time period, the discrete degree of leakage current of each varistor at all times and the difference in leakage current between all adjacent times are analyzed to determine the leakage current fluctuation of each varistor at the current moment; by calculating the temperature extreme difference of each varistor and the discrete degree of all elements in the leakage current coupling sequence within the preset time period before the current moment, the leakage current coupling abnormality of each varistor at the current moment is determined, and combined with the leakage current fluctuation, the damage degree of each varistor at the current moment is determined; Within the preset time length, by analyzing the complexity of the mutation data in the voltage of each varistor at all times and the difference in voltage between all adjacent moments, the voltage attenuation jump degree of each varistor at the current moment is determined; within the preset time length, based on the similarity of all voltage change trends between each varistor and each varistor connected in parallel with it, the voltage consistency of each varistor at the current moment is determined, and combined with the voltage attenuation jump degree, the voltage anomaly of each varistor at the current moment is determined; The lightning protection detection module is used to determine the degradation factor of each varistor at the current moment based on the damage degree and the voltage abnormality, so as to judge the lightning protection detection accuracy at the current moment.

2. An intelligent SPD lightning protection detection system according to claim 1, characterized in that: The step of constructing a leakage current-temperature coupling sequence for each varistor at the current moment includes: The ratios between all leakage current peaks and temperature peaks with the same number for each varistor within a preset time period before the current moment are calculated, and all the ratios are combined into a leakage current coupling sequence for each varistor at the current moment.

3. An intelligent SPD lightning protection detection system according to claim 1, characterized in that: The leakage current fluctuation of each varistor at the current moment is: the result of the positive fusion of the cumulative result of the leakage current difference between all adjacent moments of each varistor within a preset time period before the current moment and the leakage current discrete degree at all moments.

4. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The leakage current coupling abnormality of each varistor at the current moment is: the temperature extreme difference of each varistor within a preset time period before the current moment is divided by the discrete degree of all elements in the leakage current coupling sequence.

5. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The damage degree of each varistor at the current moment is a normalized value of the multiplication result of the leakage current fluctuation degree and the leakage current coupling anomaly degree of each varistor at the current moment.

6. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The expression of the voltage attenuation jump degree of each varistor at the current moment is: Where, Indicates the voltage attenuation jump degree of varistor i at the current moment; Represents the cumulative sum of all elements in the first-order difference sequence of the voltage of varistor i at all times within a preset time period before the current moment; The Hurst index of the voltage mutation data of the varistor i at all times within the preset time period before the current moment; Represents the preset adjustment parameter; exp( ) represents the exponential function with a natural constant as the base.

7. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The method for determining the voltage consistency of each varistor at the current moment is: The similarity of the first-order difference sequence of the voltage between each varistor and each varistor connected in parallel with it at all times is calculated, and the cumulative sum of the similarities between each varistor and all the varistors connected in parallel with it is used as the voltage consistency of each varistor at the current moment.

8. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The voltage anomaly degree of each varistor at the current moment is the ratio of the voltage attenuation jump degree to the voltage consistency degree of each varistor at the current moment.

9. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: The degradation factor of each varistor at the current moment is a normalized value of the product of the damage degree of each varistor and the voltage abnormality degree at the current moment.

10. The intelligent SPD lightning protection detection system according to claim 1, characterized in that: Determining the lightning protection detection accuracy at the current moment includes: If the degradation factor of any varistor at the current moment is greater than or equal to the preset degradation threshold, the SPD lightning protection detection accuracy at the current moment is unqualified; otherwise, the SPD lightning protection detection accuracy at the current moment is qualified.

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