A method and system for estimating the fire time of a conductor touching a tree fault based on long-time window area detection

Abstract

The application discloses a kind of long-time window area detection-based wire contact tree fault fire time estimation method and system, comprising: obtaining the energy required for test tree and wire to contact from the time of contact to fire during simulation test process, and building test power frequency amplitude waveform curve diagram, and obtaining first area threshold value;Obtain the amplitude of the zero sequence current power frequency component of the single-phase conductor at the protection device, and obtain the power frequency amplitude waveform curve according to the amplitude of the zero sequence current power frequency component;The power frequency amplitude waveform curve is filtered and smoothed, and all extreme points on the curve are obtained, the total area of the triangle composed of each extreme point is calculated with respect to the extreme point;The total area is compared with the first area threshold value, and the wire contact tree fault fire estimation time is obtained.Through the analysis of tree fire and amplitude change, the fire time detection method based on area size is proposed, which provides a new perspective for the development of fire fighting strategy and fire prevention.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of estimation of the moment of the fault of the conductor touching the tree, and in particular to a method and system for estimating the moment of the fault of the conductor touching the tree based on long-time window area detection. BACKGROUND

[0002] In the distribution network fault, the high impedance grounding fault is a common form, accounting for about 5% to 10%. When the overhead line contacts with sand, branches, concrete and other media, the grounding resistance is nonlinear and the resistance value is as high as several hundred to several thousand ohms, which is called high impedance grounding fault (HIF). The Institute of Electrical and Electronic Engineers (IEEE) defines HIF as a line grounding through grass, concrete, branches and other media in the neutral point effective grounding system, but it cannot be detected by the conventional overcurrent protection device. In the neutral point non-effective grounding system, there is no clear definition of HIF, and researchers believe that the resistance value of HIF is between several hundred ohms and several tens of kilohms. The occurrence form of HIF is various, mainly divided into three types, namely, the broken line grounding through non-metallic media such as grass and asphalt; the tree flashover caused by the branches blown by the wind; and the fault caused by the contact between the drooping line and the human body or other conductive body. The single-phase tree grounding fault of the overhead conductor belongs to one of the HIFs.

[0003] At present, researchers at home and abroad have carried out test simulation on the triggering effect of the electrical conductor on the trees, and have further studied the mechanism of tree ignition and electrical quantity change on this basis. Although there have been preliminary studies on the correlation between the tree ignition mechanism and the electrical characteristics and ignition process, the mechanism analysis of how the fire develops after the tree is ignited, and how to link the electrical characteristics with the tree ignition process to provide guidance for actual fire engineering is still relatively scarce. Therefore, the present application carries out test simulation of single-phase tree grounding of the conductor in an open environment, and then analyzes the relationship between the electrical characteristics and the physical phenomena through in-depth analysis of the principles of vegetation ignition and amplitude change. Through the combination of experimental results and theoretical analysis, a method for estimating the moment of the fault of the conductor touching the tree based on long-time window area detection is proposed. SUMMARY

[0004] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above existing problems, the present application is proposed.

[0006] Therefore, the application provides a long-time window area detection-based conductor tree contact fault fire time estimation method and system, which can solve the problems mentioned in the background art.

[0007] To solve the above technical problems, the application provides the following technical solutions.

[0008] In the first aspect, the application provides a long-time window area detection-based conductor tree contact fault fire time estimation method, which comprises the following steps:

[0009] Obtaining the energy required for the test tree and the conductor to contact and catch fire during the simulation test, and establishing a test power frequency amplitude waveform curve based on time about the energy, and obtaining a first area threshold formed by the test power frequency amplitude waveform curve and the time axis;

[0010] Obtaining the zero sequence current power frequency component amplitude of the single-phase conductor at the protection device, and obtaining the power frequency amplitude waveform curve according to the zero sequence current power frequency component amplitude;

[0011] Filtering and smoothing the power frequency amplitude waveform curve to obtain all extreme points on the curve, constructing a horizontal line segment with each extreme point as a starting point, and forming several triangles together with the horizontal line segment and the vertical line segment formed by adjacent extreme points, and calculating the total area of all triangles;

[0012] Comparing the total area with the first area threshold to obtain the conductor tree contact fault fire estimation time.

[0013] As a preferred scheme of the long-time window area detection-based conductor tree contact fault fire time estimation method, the step of obtaining the energy required for the test tree and the conductor to contact and catch fire during the simulation test, and establishing a test power frequency amplitude waveform curve based on time about the energy, and obtaining a first area threshold formed by the test power frequency amplitude waveform curve and the time axis comprises the following steps:

[0014] Obtaining a first time point at which the test tree and the conductor contact and a second time point at which the test tree catches fire;

[0015] According to the first time point, the second time point, the equivalent coefficient of the zero sequence voltage amplitude, and the test power frequency amplitude waveform curve, the energy required for the test tree to contact and catch fire is calculated;

[0016] According to the energy, the area enclosed by the test power frequency amplitude waveform curve and the time axis is obtained, and the triangular area is formed after optimization processing, and the triangular area is corrected and set as the first area threshold of the fire.

[0017] As a preferred scheme of the long-time window area detection based estimation method of the wire-tree contact fault fire time point, the first time point of the test tree contacting the wire and the second time point of the test tree catching fire are obtained by:

[0018] The whole process of the test tree catching fire is recorded by the camera equipment.

[0019] According to the video data recorded by the camera equipment, the first time point of the test tree contacting the wire and the second time point of the test tree catching fire are obtained.

[0020] As a preferred scheme of the long-time window area detection based estimation method of the wire-tree contact fault fire time point, the first time point of the test tree contacting the wire and the second time point of the test tree catching fire are obtained by:

[0021] The sampling data of the zero-sequence current frequency component amplitude is obtained at every preset time interval in a preset period.

[0022] According to the sampling data, a frequency amplitude waveform curve of the preset period is obtained.

[0023] As a preferred scheme of the long-time window area detection based estimation method of the wire-tree contact fault fire time point, the first time point of the test tree contacting the wire and the second time point of the test tree catching fire are obtained by:

[0024] The frequency amplitude waveform curve is smoothed.

[0025] The first derivative of the smoothed curve is calculated, and the extreme points are calculated according to the first derivative.

[0026] The difference of each extreme point is calculated, and the position of the extreme point is determined according to the positive and negative of the difference value.

[0027] The region with negative slope of the line segment is deleted, and the triangle surrounded by the line segment with positive slope is retained.

[0028] The retained positive slope triangle is reconnected, and the total area of all triangles is calculated.

[0029] As a preferred scheme of the long-time window area detection based estimation method of the wire-tree contact fault fire time point, the first time point of the test tree contacting the wire and the second time point of the test tree catching fire are obtained by:

[0030] If the total area is less than the first area threshold, the amplitude of the power frequency component of the zero sequence current of the single-phase conductor at the protection device is re-acquired, and the calculation is restarted until the total area is not less than the first area threshold;

[0031] If the total area is greater than or equal to the first area threshold, it is determined that the total area is equal to the first area threshold at the last time point on the time axis, or the time point when the total area is greater than the first area threshold is the fire starting point.

[0032] As a preferred scheme of the method for estimating the fire starting time of the conductor touching tree fault based on long-time window area detection, in the application, the first area threshold set after the correction of the triangular area includes:

[0033] The average area and the area standard deviation under the simulation test are acquired.

[0034] The corrected area threshold is obtained according to the average area and the area standard deviation.

[0035] In a second aspect, the application provides a system for estimating the fire starting time of the conductor touching tree fault based on long-time window area detection, which comprises:

[0036] A first area acquisition module is configured to acquire the energy required for the test tree and the conductor to contact and then to catch fire during the simulation test, to establish a time-based test power frequency amplitude waveform curve about the energy, and to acquire a first area threshold formed by the test power frequency amplitude waveform curve and the time axis.

[0037] A curve acquisition module is configured to acquire the amplitude of the power frequency component of the zero sequence current of the single-phase conductor at the protection device, and to acquire a power frequency amplitude waveform curve according to the amplitude of the power frequency component of the zero sequence current.

[0038] A second area acquisition module is configured to perform filtering and smoothing processing on the power frequency amplitude waveform curve to obtain all extreme points on the curve, to construct a horizontal line segment with each extreme point as a starting point, to form several triangles together with the horizontal line segment and the vertical line segment formed by adjacent extreme points, and to calculate the total area of all the triangles.

[0039] A comparison module is configured to compare the total area with the first area threshold to obtain the estimated time of the conductor touching tree fault.

[0040] In a third aspect, the application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method described above when executing the computer program.

[0041] In a fourth aspect, the present application provides a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method as described above.

[0042] Compared with the prior art, the present application has the beneficial effects that: the present application provides a conductor tree contact fault fire time estimation method and system based on long-time window area detection, obtains the energy required from the contact of the test tree and the conductor to the ignition during the simulation test process, establishes a time-based test power frequency amplitude waveform curve about the energy, and obtains a first area threshold formed by the test power frequency amplitude waveform curve and the time axis; obtains the power frequency component amplitude of the zero sequence current of the single-phase conductor at the protection device, obtains the power frequency amplitude waveform curve according to the zero sequence current power frequency component amplitude, performs filtering and smoothing processing on the power frequency amplitude waveform curve to obtain all extreme points on the curve, constructs a horizontal line segment with each extreme point as a starting point, and forms several triangles together with the horizontal line segment and the vertical line segment formed by the adjacent extreme points, and calculates the total area of all triangles; compares the total area with the first area threshold to obtain the conductor tree contact fault fire estimation time. Through in-depth analysis of the tree fire and amplitude change principle, the relationship between the electrical characteristics and the physical phenomena is combed, a fire time detection method based on the area size is proposed, and the area threshold of the amplitude when the vegetation ignites is obtained. The area threshold has applicability in most tree fire scenarios, and this finding provides a beneficial reference for actual fire fighting engineering and provides a new perspective for the development of fire fighting strategies and fire prevention. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0044] Figure 1 A method flow chart of a conductor tree contact fault fire time estimation method and system based on long-time window area detection provided for an embodiment of the present application;

[0045] Figure 2 A principle diagram of a conductor tree contact fault simulation test platform of a conductor tree contact fault fire time estimation method and system based on long-time window area detection provided for an embodiment of the present application;

[0046] Figure 3 A current amplitude waveform schematic diagram after median filtering processing in a simulation test of a conductor tree contact fault fire time estimation method and system based on long-time window area detection provided for an embodiment of the present application;

[0047] Figure 4 A fault detection area schematic diagram of a long-time window area detection based conductor tree contact fault fire time estimation method and system provided for an embodiment of the present application;

[0048] Figure 5 A total area schematic diagram of a positive slope triangle of a long-time window area detection based conductor tree contact fault fire time estimation method and system provided for an embodiment of the present application;

[0049] Figure 6 A schematic diagram in the interval of the fire point under the same comparison experiment of the direction of the zero sequence current and the unbalanced current of a long-time window area detection based conductor tree contact fault fire time estimation method and system provided for an embodiment of the present application;

[0050] Figure 7 A schematic diagram in the interval of the fire point under the opposite comparison experiment of the direction of the zero sequence current and the unbalanced current of a long-time window area detection based conductor tree contact fault fire time estimation method and system provided for an embodiment of the present application;

[0051] Figure 8 An internal structure diagram of a computer device of a long-time window area detection based conductor tree contact fault fire time estimation method and system provided for an embodiment of the present application. DETAILED DESCRIPTION

[0052] In order to make the above objectives, characteristics and advantages of the present application more apparent, obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0053] Embodiment 1

[0054] Reference Figures 1-8 For the first embodiment of the present application, the embodiment provides a long-time window area detection based conductor tree contact fault fire time estimation method and system, including a long-time window area detection based conductor tree contact fault fire time estimation method and a long-time window area detection based conductor tree contact fault fire time estimation system, wherein the long-time window area detection based conductor tree contact fault fire time estimation method includes:

[0055] Before the embodiments of the present application are described in detail, for the sake of clarity, some related concepts are first explained.

[0056] Arcing time: This is the time it takes for an electrical arc to form between two conductors when they come into contact. It is an important parameter in understanding the behavior of electrical systems and can be used to estimate the severity of a fault.

[0057] Power frequency amplitude waveform curve: Power frequency usually refers to the frequency of industrial electricity, which is 50Hz or 60Hz for most countries. In power systems, the "power frequency amplitude waveform curve" describes the graph of current or voltage changing over time, where the shape of the wave reflects the periodic changes of power frequency AC. This curve can show the state of power transmission, including normal operation, abnormal changes during fault occurrence, etc. By analyzing the waveform, engineers can understand the stability of the system, the type and severity of faults.

[0058] Zero sequence current power frequency component amplitude: In a three-phase power system, the three-phase currents should be balanced under normal circumstances, and their vector sum should theoretically be zero. However, when a ground fault occurs (such as a conductor touching a tree), a zero sequence current will be generated, which is the part of the current that is not balanced among the three phases. The "zero sequence current power frequency component amplitude" specifically refers to the size of the component corresponding to the power frequency in this unbalanced current, which is a key indicator for detecting ground faults. By monitoring the zero sequence current, faults can be quickly located and judged.

[0059] Filtering and smoothing: Filtering and smoothing is a signal processing technique used to remove noise or irregular fluctuations in the original data, so that the basic characteristics or trends of the signal can be more clearly observed. In this context, it may involve low-pass filtering of current and voltage waveform data, i.e. allowing low-frequency signals to pass while attenuating high-frequency signals (such as random noise), or using median filtering, mean filtering, etc. to reduce data spikes or fluctuations, making the waveform smoother for subsequent analysis and processing, such as accurately identifying extreme points and calculating areas.

[0060] In related technologies, the estimation of the ignition time caused by conductor-tree fault usually relies on traditional monitoring and diagnosis methods, which may have some limitations such as insufficient sensitivity to fault signals, slow response, high false alarm rate, etc.

[0061] The application provides a long-time window area detection-based conductor contact tree fault fire time estimation method which can effectively solve the above-mentioned problems.

[0062] Figure 1 A method flowchart of a long-time window area detection-based conductor contact tree fault fire time estimation method and system is shown, including:

[0063] S101, acquiring energy required for a test tree and a conductor to be in contact from a contact time to a fire time in a simulation test process, and establishing a test power frequency amplitude waveform curve diagram based on time about the energy, and acquiring a first area threshold formed by a test power frequency amplitude waveform curve and a time axis;

[0064] In the embodiment of the application, the simulation test platform is built, and the simulation test platform includes a power frequency test power supply, a data acquisition and processing module and a test tree; the power frequency test power supply is used for power supply of the conductor; one end of the test tree is in contact with the single-phase conductor, and the other end is connected with the ground; the data acquisition and processing module is connected with the conductor of the test tree;

[0065] As shown in Figure 2 the simulation test platform includes a power frequency test power supply, a data acquisition and processing module and a test tree; the power frequency test power supply is used for power supply of the conductor; one end of the test tree is in contact with the single-phase conductor, and the other end is connected with the ground; the data acquisition and processing module is connected with the conductor of the test tree;

[0066] In the embodiment of the application, some representative tree species commonly seen in forests are tested, for example, national locust, poplar, elm, katsura and pine, etc., so that the test is universal and the fire time of each tree is recorded in detail, which is helpful for the research on the fire characteristics of each tree species in the following.

[0067] As shown in Table 1, different tree species are shown, and the fire time of each tree is recorded in detail, so that the fire characteristics of different tree species can be fully understood in subsequent analysis.

[0068] Table 1: Related parameters of different tree species.

[0069] Tree species Tree diameter / m Height of contact point from ground / m Sophora japonica 0.12 1 Sophora japonica 0.105 2 Sophora japonica 0.12 2.17 Poplar 0.10 1.8 Elm 0.06 2 Koelreuteria paniculata 0.12 1.5 Pine 0.06 1.5

[0070] It should be noted that, since the tree resistance during the fault process can reach thousands of ohms and the voltage does not appear obvious distortion, in order to simplify the subsequent analysis and calculation, the influence of the fault on the voltage is ignored in the embodiment. Due to the change of circuit characteristics, the influence of tree conduction characteristics, the change of contact area and contact quality and other factors, only the amplitude of the fault current signal shows obvious amplitude. Therefore, the current amplitude is focused on to further explore the generation and curve characteristics of them in the fault signal.

[0071] In the embodiment of the present application, in the zero sequence current amplitude, the proportion of the power frequency component in the current is particularly significant. The power supply uses a power frequency test power supply, a voltage regulator and a 10kV transformer to realize power supply of the 10kV power supply voltage to the conductor; the conductor forms a loop with the tree and the ground; at the same time, the tree branches are pruned as necessary, the purpose is to reduce the influence of unstable factors such as tree branches, so as to better observe the fault development trend of the tree line.

[0072] Further, the data acquisition and processing module acquires the current signal of the test tree, and processes the current signal to obtain a test power frequency amplitude waveform curve;

[0073] In the embodiment of the present application, the current signal during the fault is collected by the current transformer at a frequency of 10kHz, considering that the change amount of the current within 1 second is relatively weak, the first 200 sampling points within each second are selected for analysis and reference. Subsequently, it is observed that there is a significant peak phenomenon in the curve, based on the consideration of long-term analysis of the current amplitude, the time interval between each point in the data should be shortened, so as to facilitate the observation of the current amplitude characteristics, reduce the influence of the remaining peaks on the waveform, and at the same time not lose more detailed information. Therefore, the current signal during the fault is subjected to twice median filtering processing with a wide window of 4 and a wide window of 50, and the current amplitude waveform is obtained as shown in Figure 3 .

[0074] Further, the first time point at which the test tree contacts the conductor and the second time point at which the test tree catches fire are recorded;

[0075] Further, according to the first time point, the second time point, the equivalent coefficient of the zero sequence voltage amplitude and the test power frequency amplitude waveform curve, the energy required for the test tree from contacting the conductor to catching fire is calculated;

[0076] Further, based on the mechanism of tree fire, it is assumed that the energy required in the process from the contact of the tree with the conductor to the tree catching fire mainly comes from the energy transmission of the arc current and the work done by the current in the tree, and the energy required for the tree to catch fire is:

[0077]

[0078] Wherein, t1 is the contact time of the conductor and the tree; t2 is the time when the tree catches fire and continues to burn; E th is the required energy; V(t) is the zero sequence voltage amplitude varying with time; I(t) is the zero sequence current amplitude varying with time.

[0079] Further, due to the high resistivity of the tree, the zero sequence voltage amplitude has almost no significant fluctuation during the fault process. Therefore, it can be regarded as a constant coefficient. In addition, the zero sequence current amplitude mainly contains the power frequency component, so the power frequency amplitude can be used to approximate the replacement. Considering the above factors, the calculation formula of the fire energy is simplified as follows:

[0080]

[0081] Wherein, a is the equivalent coefficient of the zero sequence voltage amplitude; t1 is the contact time of the conductor and the tree; t2 is the open fire time of the tree fire lasting combustion; I pf (t) is the power frequency amplitude changing with time.

[0082] It should be noted that the test process of the tree being ignited is recorded by a high-definition camera, and the test phenomenon is observed until the discharge channel penetrates the vegetation and a short circuit occurs. At the same time, a thermal imaging temperature measuring instrument is used to observe the temperature change of the tree; according to the video data recorded by the camera equipment, the first time point of the test tree contacting the conductor and the second time point of the test tree being ignited are obtained.

[0083] Further, according to the area surrounded by the test power frequency amplitude waveform curve and the time axis, the triangular area is formed by optimization processing, and the triangular area is corrected to set the first area threshold of the fire.

[0084] The area surrounded by the power frequency amplitude curve changing with time and the time axis is:

[0085]

[0086] In the embodiments of the present application, there is a certain linear relationship between the energy required for the tree to form an open fire lasting combustion and the area surrounded by the amplitude change curve. As Figure 4 shown, the triangular area of the interval of the required detection area is proportional to the area surrounded by the amplitude change curve and the time axis, although the triangular area cannot be completely equal to the size of the energy input, but can reflect the energy input to a certain extent. In other words, the larger the area, the more energy input, and the higher the possibility of tree fire. Therefore, from the perspective of mechanism, the triangular area is taken as the basis, and the area threshold is set, which can be regarded as a kind of method with high feasibility for detecting the fire time of the fault occurrence.

[0087] Further, obtaining the first time point of the test tree contacting the conductor and the second time point of the test tree being ignited includes:

[0088] Obtaining the test whole process of the test tree being ignited recorded by the camera equipment;

[0089] According to the video data recorded by the camera equipment, the first time point of contact between the test tree and the conductor and the second time point of recording the fire of the test tree are obtained.

[0090] The first area threshold value of the fire is set after correcting the area of the triangle, including:

[0091] Obtain the mean area and area standard deviation under the simulation test;

[0092] According to the mean area and the area standard deviation, a corrected area threshold value is obtained.

[0093] In the embodiments of the present application, the corrected area threshold value is obtained according to the mean area and the area standard deviation, and the correction formula is:

[0094] S min = S ave - δ

[0095] Wherein, S min is the area threshold value; S ave is the mean area of the experimental results; δ is the standard deviation.

[0096] It should be noted that by processing and analyzing the data of the actual simulation test, a more accurate area threshold value is determined. By obtaining the mean area and area standard deviation under the simulation test, and correcting based on these statistical data, the area threshold value can be more close to the actual situation, and the accuracy and reliability of detecting tree fire can be improved.

[0097] Furthermore, the corrected area threshold value not only considers the average value of the test results, but also considers the dispersion degree of the data, i.e. the standard deviation. This helps to adapt to the differences that may exist under different test conditions, making the area threshold value more universal and stable.

[0098] In addition, through detailed recording and analysis of the test process, including the use of high-definition cameras and thermal imaging thermometers and other equipment, the key time points of tree contact with conductor and tree fire can be obtained. These time points are crucial for subsequent energy calculation and area threshold setting, which helps to more accurately judge the tree fire situation.

[0099] In summary, through the implementation of the above steps, the method can correct and optimize the area threshold value using simulation test data, improve the accuracy and reliability of tree fire detection. At the same time, combined with detailed test records and analysis, the mechanism and process of tree fire can be more comprehensively understood, which provides strong support for subsequent fault prevention and response measures.

[0100] S102, obtain the zero sequence current frequency component amplitude of the single-phase conductor at the protection device, and obtain the frequency amplitude waveform curve according to the zero sequence current frequency component amplitude;

[0101] The zero-sequence current power frequency component amplitude of the single-phase conductor at the protection device is obtained, and the power frequency amplitude waveform curve is obtained according to the zero-sequence current power frequency component amplitude, comprising:

[0102] The sampling data of the zero-sequence current power frequency component amplitude collected every other preset time interval in a preset period is obtained;

[0103] The power frequency amplitude waveform curve of a preset period is obtained according to the sampling data.

[0104] In the embodiments of the present application, the protection device can be a relay protection device, a line protection relay, a distributed feeder automation device, etc. In order to realize the functions of obtaining the zero-sequence current power frequency component amplitude and drawing the power frequency amplitude waveform curve, the protection device is usually equipped with a high-performance current transformer, an AD converter (analog signal to digital signal), a microprocessor and necessary software algorithms. The software part is responsible for controlling the sampling frequency, executing data processing algorithms (such as filtering, denoising), calculating the zero-sequence current component, and generating a waveform curve according to the sampling data.

[0105] S103, filtering and smoothing the power frequency amplitude waveform curve to obtain all extreme points on the curve, constructing a horizontal line segment with each extreme point as a starting point, and forming several triangles with the horizontal line segment formed by adjacent extreme points and the vertical line segment, and calculating the total area of all triangles;

[0106] Filtering and smoothing the power frequency amplitude waveform curve to obtain all extreme points on the curve, constructing a horizontal line segment with each extreme point as a starting point, and forming several triangles with the horizontal line segment formed by adjacent extreme points and the vertical line segment, and calculating the total area of all triangles, comprising:

[0107] Smoothly processing the power frequency amplitude waveform curve;

[0108] Calculating the first derivative of the curve after smoothing, and calculating the extreme points according to the first derivative;

[0109] Differential calculation is performed on each extreme point, and the position of the extreme point is determined according to the positive and negative of the differential value;

[0110] Delete the region with negative slope of the line segment, and retain the triangles surrounded by the line segments with positive slope;

[0111] The retained positive slope triangles are re-spliced, and the total area of all triangles is calculated.

[0112] It should be noted that after obtaining the triangular area, due to the high overall resistance of the trees, the temperature rise process is relatively slow, so in the early stage of the fault, the amplitude as a whole shows an upward trend. However, the influence of contact resistance, arc extinction and other factors on the amplitude may cause a temporary decrease. Therefore, the region with negative slope of the line segment is selected to be deleted, only the triangular area surrounded by the line segment with positive slope is retained, and the total area of the positive slope triangular area is calculated. The re-splicing process may form one or more triangles, as shown in Figure 5 The total area of all triangles is calculated.

[0113] It should be noted that by filtering and smoothing the power frequency amplitude waveform curve, noise and interference can be effectively removed, making the waveform curve smoother and conducive to accurate identification and calculation of extreme points. Filtering and smoothing can eliminate waveform fluctuations caused by measurement errors, electromagnetic interference and other factors, improving data reliability and stability.

[0114] It should be noted that the first derivative of the smoothed curve is calculated to determine the extreme points, which can accurately locate the extreme positions of the waveform curve. The extreme points reflect the local maximum or minimum value of the zero sequence current amplitude, which is of great significance for analyzing tree fire faults. By identifying the extreme points, the electrical characteristics of the tree contact with the conductor can be further analyzed to determine whether the tree is likely to catch fire.

[0115] It should be noted that by constructing a horizontal line segment with each extreme point as the starting point, and forming several triangles with the horizontal line segment and the vertical line segment formed by the adjacent extreme points, and calculating the total area of all triangles, the change of the zero sequence current can be quantitatively reflected. This triangular area calculation method can intuitively show the dynamic change of the zero sequence current during the fault occurrence, providing an effective basis for judging tree fire.

[0116] It should be noted that by deleting the line segment with negative slope, and retaining the triangular area surrounded by the line segment with positive slope, the influence of temporary decrease caused by contact resistance, arc extinction and other factors on area calculation can be excluded. This processing method makes the area calculation more accurate and avoids misjudgment caused by non-fault factors.

[0117] It should be noted that the retained positive slope triangular area is re-spliced and the total area is calculated, which can further simplify the calculation process and improve the calculation efficiency. The re-spliced triangular area can more comprehensively reflect the overall trend of the zero sequence current, providing strong support for subsequent fault analysis and processing.

[0118] S104, compare the total area with the first area threshold to obtain the estimated time of the conductor tree fault fire.

[0119] In the embodiment of the present application, the total area is compared with the first area threshold value to obtain the estimated time of the conductor tree contact fault fire.

[0120] If the total area is less than the first area threshold value, the amplitude of the zero sequence current power frequency component of the single-phase conductor at the protection device is re-acquired, and the calculation is restarted until the total area is not less than the first area threshold value.

[0121] If the total area is greater than or equal to the first area threshold value, it is determined that the total area equal to the first area threshold value is the fire point at the last time point on the time axis, or the time point when the total area is greater than the first area threshold value is the fire point.

[0122] It should be noted that the present application proposes a conductor tree contact fault fire time estimation method and system based on long-time window area detection, acquires the energy required for the test tree and the conductor to contact from the time of contact to the time of fire during the simulation test process, establishes a test power frequency amplitude waveform curve based on time about the energy, and acquires a first area threshold value formed by the test power frequency amplitude waveform curve and the time axis; acquires the amplitude of the zero sequence current power frequency component of the single-phase conductor at the protection device, and acquires the power frequency amplitude waveform curve according to the amplitude of the zero sequence current power frequency component; the power frequency amplitude waveform curve is filtered and smoothed to obtain all extreme points on the curve, a horizontal line segment is constructed from each extreme point as a starting point, and a plurality of triangles are formed together with the horizontal line segment and the vertical line segment formed by adjacent extreme points, and the total area of all triangles is calculated; the total area is compared with the first area threshold value to obtain the estimated time of the conductor tree contact fault fire. Through in-depth analysis of the principle of tree fire and amplitude change, the relationship between electrical characteristics and physical phenomena is sorted out, a fire time detection method based on area size is proposed, and an area threshold value of the amplitude when the vegetation catches fire is obtained. The area threshold value has applicability in most tree fire scenarios, which provides a useful reference for actual fire fighting engineering and provides a new perspective for the development of fire fighting strategies and fire prevention.

[0123] The embodiment also provides a conductor tree contact fault fire time estimation system based on long-time window area detection, comprising:

[0124] The first area acquisition module is configured to acquire the energy required for the test tree and the conductor to contact from the time of contact to the time of fire during the simulation test process, establish a test power frequency amplitude waveform curve based on time about the energy, and acquire a first area threshold value formed by the test power frequency amplitude waveform curve and the time axis.

[0125] The curve acquisition module is configured to acquire the amplitude of the zero sequence current power frequency component of the single-phase conductor at the protection device, and acquire the power frequency amplitude waveform curve according to the amplitude of the zero sequence current power frequency component.

[0126] The second area obtaining module is configured to filter and smooth the power frequency amplitude waveform curve, obtain all extreme points on the curve, construct a horizontal line segment with each extreme point as a starting point, and form a plurality of triangles together with the horizontal line segment and the vertical line segment formed by adjacent extreme points, and calculate the total area of all the triangles.

[0127] The comparison module is configured to compare the total area with the first area threshold to obtain the estimated time of the conductor tree fault fire.

[0128] The above each unit module can be embedded in or independent of the processor in the computer device in hardware form, or can be stored in the memory in the computer device in software form, so as to call and execute the operations corresponding to the above each module by the processor.

[0129] The embodiment also provides a computer device which can be a terminal, and an internal structure diagram of the computer device can be as shown in Figure 8 The computer device includes a processor, a memory, a communication interface, a display screen and an input device which are connected through a system bus. The processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The communication interface of the computer device is configured to perform wired or wireless communication with an external terminal. The wireless communication can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The computer program is executed by the processor to implement a long-time window area detection based conductor tree fault fire time estimation method. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or can be a key, trackball or touchpad arranged on the shell of the computer device, or can be an external keyboard, touchpad or mouse, etc.

[0130] The embodiment also provides a computer readable storage medium having a computer program stored thereon. The computer program is executed by the processor to implement the following steps:

[0131] Obtain the energy required from the contact of the test tree and the conductor to the fire in the simulation test process, and establish a time-based test power frequency amplitude waveform curve graph about the energy, and obtain a first area threshold formed by the test power frequency amplitude waveform curve and a time axis;

[0132] Obtain the zero sequence current power frequency component amplitude of the single-phase conductor at the protection device, and obtain the power frequency amplitude waveform curve according to the zero sequence current power frequency component amplitude;

[0133] The total area is compared with the first area threshold to obtain the estimated time of the conductor tree contact fault fire.

[0134] The total area is compared with the first area threshold to obtain the estimated time of the conductor tree contact fault fire.

[0135] Embodiment 2

[0136] Reference Figures 1-8 For an embodiment of the present application, a conductor tree contact fault fire time estimation method and system based on long window area detection are provided. In order to verify the beneficial effects of the present application, scientific demonstration is carried out through experiments.

[0137] In order to better understand the relationship between the electrical characteristics and physical phenomena of tree contact conductor fire, the test results of tree contact conductor fire are observed, including the following stages:

[0138] Stage I:

[0139] When the conductor contacts the tree trunk or branch, an electric circuit is formed with the tree body and the ground. During this process, the ionized substances in the free water in the tree tissue are affected by the electric field, causing strong electrodynamic movement. These ions generate Joule heat due to the work done by the current, which in turn causes the temperature of the water in the plant tissue to gradually rise. Due to the influence of heat conduction, the heat in the free water begins to spread to the inside of the plant tissue and the surrounding environment, causing the overall plant body temperature to gradually rise, eventually approaching the boiling point. At the same time, the gap near the contact point between the conductor and the tree bark is affected by the strong electric field, resulting in gap breakdown and the formation of a small electric arc, i.e. several irregular bright spots are formed on the surface of the bark around the contact point.

[0140] As the temperature of the tree rises, the tree begins to undergo thermal decomposition, resulting in the production of colorless and odorless gases such as water vapor, carbon dioxide, carbon monoxide, wood tar, acetic acid, and methanol. These gases mix and condense into organic aerosols, dust, and smoke, i.e. the observed "smoke" phenomenon. Subsequently, the combustible gases volatilize in the air and mix with oxygen. However, the amount of combustible gas produced during the initial stage of the fault is relatively small, and the temperature of the contact point arc is sufficient to reach the ignition temperature of the combustible gas. Therefore, only intermittent flames are produced near the contact point.

[0141] Stage II:

[0142] In wood, the main chemical elements include carbon, hydrogen, oxygen, and nitrogen, with the proportions of 49-50%, 6%, 45-50%, and 0.1-1%, respectively. These elements constitute the main organic molecules of wood, and the simple chemical formula can be expressed as C47O46H6N, which mainly constitutes the three major chemical components of lignin, cellulose, and hemicellulose.

[0143] Under the action of high temperature, part of the carbon elements in wood combine with hydrogen and oxygen to form organic substances such as phenol, aldehyde, ketone, acid, and alcohol. At the same time, the remaining carbon elements are decomposed, rearranged, and combined under high temperature to form more stable carbon structures, thus promoting the formation of charcoal. Since the electric arc is first generated at the contact point, the temperature is the highest, so the carbonization path first forms from the contact point.

[0144] At this stage, the water in the tree begins to evaporate in large quantities and is released from the surface of the bark. However, due to the faster evaporation rate of water than the release rate of the bark surface, the internal water vapor of the tree accumulates, increasing the internal pressure.

[0145] After a small range of carbonization occurs near the contact point, the electrical conductivity of this area increases, making it easier for air gap breakdown to occur, thus generating an electric arc. Therefore, the carbonized part is ignited under the condition of intermittent fire and electric arc providing heat, causing the intermittent fire near the contact point to gradually transition to a continuous burning open flame.

[0146] Stage III:

[0147] During the development of the fault, the equivalent resistance of the entire tree can be divided into two parts, namely the carbonized part and the non-carbonized part. Since the electrical conductivity of the carbonized part is much higher than that of the non-carbonized part, there is a strong electric field in a small range of the non-carbonized part that is in contact with the carbonized part. This strong electric field causes the wood in this small range to break down, and the high temperature generated in the breakdown instant causes it to carbonize. Eventually, the non-carbonized part in this small range will gradually transition to the carbonized part.

[0148] With the continuous rise of the internal water vapor pressure of the tree, when the water vapor pressure exceeds the limit that the tree can withstand, due to the differences between different tree species, there are also differences in the limit of pressure that the tree can withstand. Some trees may crack the bark, while others may emit a "bang" explosion. Although the manifestations are different, the result is that the accumulated steam in the tree body is released in large quantities from the non-carbonized part.

[0149] The intermittent fire and arc formed by igniting the combustible material together provide heat, causing the covalent bonds of the carbon structure near the contact point to break. The energy released by the broken covalent bonds is manifested in the form of light and heat as the visible fire observed in the experiment. After the charcoal near the contact point is ignited, the heat of the visible fire begins to spread to the surrounding through heat conduction. Because the uncarbonized part of the tree has a high water content, it is not easy to ignite, so the heat energy of the visible fire first ignites the adjacent charcoal, forming a visible fire channel along the carbonization path.

[0150] When the tree carbonization path develops to the end, the tree is prone to breakdown region. Because the electric field at the contact point is the strongest, the wood at the contact point is the first to carbonize, producing a continuous visible fire that burns most fully. After the wood at the contact point is fully burned, it turns into incombustible inorganic matter and is affected by factors such as wind and gravity, and these inorganic matter will fall off, causing the wire to have incomplete contact with the tree. Eventually, the flame development degree of the surface of the tree accounts for about 60% of the total length of the tree, and a bright arc is generated at the core of the flame.

[0151] In summary, the wire-tree fault is often accompanied by physical phenomena such as temperature rise, wood carbonization, and water evaporation. These physical phenomena affect the overall resistance of the tree, which in turn causes the amplitude to change. Therefore, in the wire-tree fault, the amplitude change shows a consistent regularity. Based on this law, the fault point detection analysis has high reliability and universality.

[0152] Based on the analysis of the mechanism of the tree contacting the wire and the change in amplitude, it can be seen that the moment of starting the fire usually occurs during the tree warming stage. The analysis is limited to the range from the start of contact to the saturation stage of the tree warming.

[0153] Taking into account various factors such as the internal structure of the tree, water content, and external environment, it is assumed that 1 sample point is sampled per second during the detection process of the protection device, and the data is summarized and detected once every 300 sampling points.

[0154] The preset period is set to 300 seconds, the preset time interval for each collection is set to 1 second, and the data is summarized and detected once every 300 sampling points. In other embodiments, the preset period and the preset time interval can be set according to actual conditions.

[0155] A method with a window width of 5 is used to find possible extreme points.

[0156] In order to ensure the reliability of the found extreme points and prevent errors in data smoothing, the extreme points are subjected to difference calculation, and then the positions of the extreme points are determined according to the positive and negative of the difference value, to find more accurate extreme point positions, facilitating area calculation in the later stage.

[0157] After getting the triangle area, the temperature rise process is relatively slow due to the high overall resistance of the tree, so the amplitude shows an overall upward trend in the early stage of the fault. However, the influence of contact resistance, arc extinction and other factors on the amplitude may cause a temporary decrease. Therefore, the area with a negative line segment slope is deleted, only the triangle area surrounded by the line segment with a positive slope is retained, and the positive slope triangle area is reconnected. The reconnection process may form one or more triangles, as shown in Figure 5 The total area of all triangles is calculated.

[0158] If the total area is less than the area threshold, repeat steps S2-S5 to start the calculation again until the total area is not less than the area threshold; determine that the total area equal to the area threshold at the last time point on the time axis is the ignition point.

[0159] If the total area is greater than or equal to the area threshold, determine that the total area equal to the area threshold at the last time point on the time axis is the ignition point, or the time when the total area is greater than the area threshold is the ignition point.

[0160] This process detects the characteristics of the current waveform and uses the triangle area as the basis for determination, achieving accurate identification of the conductor-tree fault. This method can not only exclude the influence of unbalanced zero sequence current in the system itself, but also avoid the problem that the traditional integral method may not accurately calculate the integral when the curve has singular points or oscillation behavior.

[0161] Experimental comparison of different methods:

[0162] The current traditional fault detection method mainly uses threshold detection method to detect the effective value vector modulus of the current. Generally, in order to avoid misoperation, the threshold is usually set to twice the maximum zero sequence current amplitude at the fault time. Although this method has strong universality, it has certain limitations for faults affected by multiple factors such as tree water content, diameter, and conductor-tree contact height. For example, when the tree diameter is large and the water content is low, the overall resistance of the tree is low, causing the zero sequence current to remain below the threshold level from the beginning of the fault to the occurrence of the fire. Therefore, this threshold detection fault method has the following important shortcomings: lack of sensitivity, easy to miss the real fault or false alarm; difficult to adapt to dynamic changes, frequent calibration is required to ensure effectiveness; lack of adaptability to hidden faults and new systems.

[0163] The application carries out the test under ideal experimental conditions, and the content of unbalanced zero sequence current is extremely low, therefore, in order to better show the superiority of the method, the proposed method and the traditional threshold detection method are compared and analyzed under extreme conditions respectively. The data recorded by Tai'an 35kV Sun village transformer in table 2 shows that the amplitude of unbalanced zero sequence current existing in the system is always floating at 0.7A. Based on this data, it is assumed that the current direction is two, that is, one is the same as the zero sequence current direction when the fault occurs, and the other is opposite. In these two extreme cases, the error of the two different methods will be tested respectively, and the amplitude of 1.4A, which is twice the amplitude, is used as the data basis of the traditional threshold detection method.

[0164] Table 2: Data recorded by Tai'an 35kV Sun village transformer

[0165]

[0166] Figure 6 And Figure 7 The results of the comparative experiment are shown, it can be seen that the method proposed in the application is not sensitive to the unbalanced current of the system itself, and the starting point of the traditional threshold detection will be randomly distributed in the interval of the starting points detected in the two extreme conditions due to the influence of the unbalanced current. In order to verify the accuracy of the proposed method, TSF tests are carried out many times, involving different contact heights, diameters and tree species conditions, and the related parameters and results are shown in table 3.

[0167] Table 3: Related parameters and results.

[0168]

[0169]

[0170] Through the analysis, it can be seen that the area detection method proposed in the application can more accurately estimate the occurrence time of the fault to a certain extent, has higher sensitivity, can help the power company to locate and solve the problem faster, and thus maximally reduces the power-off time and influence.

[0171] The conductor tree contact fault ignition time estimation method based on long-time window area detection of the application utilizes the test simulation of single-phase tree contact of the conductor, through the in-depth analysis of the tree ignition and amplitude change principle, the relationship between the electrical characteristics and the physical phenomena is combed, the ignition time detection method based on the area size is proposed, the area threshold of the amplitude when the vegetation ignites is obtained, the area threshold has applicability in most tree ignition situations, through the comparison with the traditional threshold method, the superiority of the proposed method is highlighted, and this finding provides a beneficial reference for the actual fire fighting engineering, and provides a new perspective for the formulation of fire fighting strategy and fire prevention.

[0172] In a preferred embodiment of this application, the area threshold for ignition after correcting the area of ​​the triangle specifically refers to:

[0173] Obtain the mean and standard deviation of the area under the simulated experiment;

[0174] The corrected area threshold is obtained based on the mean area and the standard deviation of the area.

[0175] The corrected formula is:

[0176] S min =S ave -δ

[0177] In the formula: S min S is the area threshold; ave δ represents the mean area of ​​the experimental results; δ is the standard deviation. In this embodiment, the threshold S is obtained based on the experimental data in Table 4. min =11.2064.

[0178] Table 4: Experimental data.

[0179] Date of experiment Area at ignition Time at ignition 11-07-23 16.8725 15 15-13-49 18.1483 17 10-37-00 10.5948 6 10-23-24 10.422 27 2023-6-3 13-20-49 16.5 11

[0180] The calculation of the triangle area is mainly affected by the distribution of extreme points and the time interval between two extreme points. Meanwhile, the magnitude of the unbalanced current in the system has no significant impact on the area of ​​the triangle to be detected. Therefore, during threshold tuning, the influence of the unbalanced current in the system itself can be ignored, thus allowing for a more accurate determination of the threshold parameters.

[0181] Based on the statistical data, the area before ignition represents the portion of the tree that has not yet reached temperature saturation at the time of ignition. Therefore, after the tree catches fire, the effective value of the zero-sequence current continues to increase, leading to a corresponding increase in the area. The area threshold setting can be appropriately adjusted upwards. On the other hand, since the aforementioned setting value is sufficient to cover the maximum unbalanced zero-sequence current, there is also a margin for downward adjustment. After weighing these factors, this study chooses to set the threshold with backward compatibility to ensure the stability and reliability of the system.

[0182] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0183] Those skilled in the art will appreciate that embodiments of the application can be readily used as software, hardware, or a combination of software and hardware. In one embodiment, the application can be implemented in software and / or firmware. In addition, those skilled in the art will further appreciate that the application can be implemented as a method, apparatus, or computer program product. Therefore, embodiments of the application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a "circuit" or "module." Furthermore, embodiments of the application can take the form of a computer program product on a computer-readable storage medium having computer program code embodied in the storage medium. The computer program code can cause a computer, processor, or other programmable data processing apparatus to effect the steps in the embodiments of the application as set forth in the description below.

[0184] The embodiments of methods, apparatuses (systems) and computer program products of the application are described herein with reference to flowchart and / or block diagrams illustrations of the methods, apparatuses (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart and / or block diagrams illustrations, and combinations of blocks in the flowchart and / or block diagrams illustrations, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing element or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof.

[0185] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof.

[0186] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof. Figure 1 one or more functions specified in the flowchart and / or block diagram block(s) or combinations thereof.

[0187] While the preferred embodiments of the application have been described, additional variations and modifications can be employed by those skilled in the art. Therefore, the appended claims are intended to cover all such variations and modifications as falling within the scope of the application.

[0188] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method for estimating the fire time of a conductor tree fault based on long-time window area detection, characterized in that, The method comprises the following steps: acquiring the energy required for a test tree and a conductor to be in contact and then to catch fire during a simulation test, and establishing a test power frequency amplitude waveform curve based on time about the energy, and acquiring a first area threshold formed by the test power frequency amplitude waveform curve and a time axis; acquiring a zero sequence current power frequency component amplitude of a single-phase conductor at a protection device, and acquiring a power frequency amplitude waveform curve according to the zero sequence current power frequency component amplitude; filtering and smoothing the power frequency amplitude waveform curve to obtain all extreme points on the curve, constructing a horizontal line segment with each extreme point as a starting point, and forming a plurality of triangles together with the horizontal line segment and a vertical line segment formed by adjacent extreme points, and calculating a total area of all the triangles; comparing the total area with the first area threshold to obtain an estimated time for the conductor to catch fire due to tree fault.

2. The long-time window area detection based method for estimating the fire occurrence time of a conductor tree fault according to claim 1, characterized in that, The method comprises the following steps: acquiring a first time point at which the test tree is in contact with the conductor and a second time point at which the test tree catches fire; calculating the energy required for the test tree to catch fire from being in contact with the conductor according to the first time point, the second time point, an equivalent coefficient of the zero sequence voltage amplitude, and the test power frequency amplitude waveform curve; obtaining an area enclosed by the test power frequency amplitude waveform curve and the time axis according to the energy, optimizing the area to form a triangular area, and setting the triangular area as the first area threshold after correction.

3. The long-time window area detection based line contact tree fault fire time estimation method of claim 2, wherein, The method comprises the following steps: acquiring a test whole process of the test tree being ignited recorded by a camera device; obtaining the first time point at which the test tree is in contact with the conductor and the second time point at which the test tree catches fire according to video data recorded by the camera device.

4. The long-time window area detection based line contact tree fault fire time estimation method of claim 3, wherein, The method comprises the following steps: acquiring sampling data of the zero sequence current power frequency component amplitude collected every other preset time interval within a preset period; obtaining a power frequency amplitude waveform curve of the preset period according to the sampling data.

5. The long-time window area detection based line contact tree fault fire time estimation method of claim 4, wherein, The method comprises the following steps: smoothing the power frequency amplitude waveform curve; calculating a first derivative of the smoothed curve, and calculating extreme points according to the first derivative; performing difference calculation on each extreme point, and determining the position of the extreme point according to the positive and negative of the difference value; deleting a region with a negative slope, and retaining triangles enclosed by line segments with a positive slope; reconnecting the retained triangles with a positive slope, and calculating a total area of all the triangles.

6. The long-time window area detection based line contact tree fault fire time estimation method of claim 5, wherein, The comparing the total area with the first area threshold value to obtain the estimated time of the tree fault fire of the conductor includes: If the total area is less than the first area threshold value, the amplitude of the power frequency component of the zero sequence current of the single-phase conductor at the protection device is re-acquired, and the calculation is restarted until the total area is not less than the first area threshold value; If the total area is greater than or equal to the first area threshold value, it is determined that the total area is equal to the first area threshold value at the last time point on the time axis, or the time point when the total area is greater than the first area threshold value is the fire point.

7. The long-time window area detection based line contact tree failure fire time estimation method of claim 6, wherein, The first area threshold value of the fire is set after the correction of the triangular area includes: The mean area and the area standard deviation under the simulation test are acquired; The corrected area threshold value is obtained according to the mean area and the area standard deviation.

8. A long-time window area detection-based conductor contact tree fault ignition time estimation system, characterized in that, It includes: The first area acquisition module is configured to acquire the energy required for the tree and the conductor to contact and ignite during the simulation test, establish a time-based test power frequency amplitude waveform curve about the energy, and acquire a first area threshold value formed by the test power frequency amplitude waveform curve and a time axis; The curve acquisition module is configured to acquire the amplitude of the power frequency component of the zero sequence current of the single-phase conductor at the protection device, and acquire a power frequency amplitude waveform curve according to the amplitude of the power frequency component of the zero sequence current; The second area acquisition module is configured to perform filtering and smoothing processing on the power frequency amplitude waveform curve to obtain all extreme points on the curve, construct a horizontal line segment with each extreme point as a starting point, and form several triangles with the horizontal line segment and the vertical line segment formed by adjacent extreme points, and calculate the total area of all triangles; The comparison module is configured to compare the total area with the first area threshold value to obtain the estimated time of the tree fault fire of the conductor. 9.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-8 when the computer program is executed by the processor. The processor executes the computer program to realize the steps of the method of any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the method of any one of claims 1 to 7.

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