Mountain fire early warning method for improving grassland distribution line grounding research and judgment capability

Abstract

The invention discloses a forest fire early warning method for improving the grounding research and judgment capability of a grassland distribution line, and relates to the field of power distribution network fault monitoring, and the method comprises the steps: obtaining a zero-sequence voltage recording file based on monitoring equipment; obtaining a first wave recording file group based on the zero-sequence voltage wave recording file of the power distribution main line group, obtaining first time of the first wave recording file group, obtaining a hidden danger event based on the first time and a first preset time range, and obtaining a hidden danger wave recording file of the hidden danger event; based on a preset zero-sequence voltage range and a second preset time range, grouping the hidden danger wave recording files to obtain a second wave recording file group, and based on wave recording data of the second wave recording file group, obtaining an external hidden danger point and an internal hidden danger point; early warning information is obtained based on the external hidden danger points and the internal hidden danger points, and the problem that according to an existing single-phase earth fault monitoring method for the grassland-crossing power distribution network line, line electrical faults can only be reduced by rapidly isolating the single-phase earth faults, and the line faults cannot be monitored in advance can be solved.

Description

Technical Field

[0001] The present invention relates to the field of distribution network fault monitoring, and specifically, to a wildfire warning method for improving the grounding judgment ability of grassland distribution lines. Background Art

[0002] Fire is one of the important factors endangering ecological security, which not only destroys natural resources but also poses a threat to people's lives and property. With the continuous expansion of the distribution network, power facilities such as wires and cables pass through forest areas in grasslands, increasing the risk of fire. For a long time, the power department and research institutions have carried out a large number of studies on the impact of wildfires on power lines and power grid operation, forming a technical system for wildfire monitoring, warning and disposal.

[0003] Currently, the distribution network lines across grasslands mainly avoid line electrical faults and thus trigger fires by quickly isolating single-phase grounding faults. Quickly isolating grounding faults can reduce the risk of fires caused by electricity, but this belongs to minimizing the losses caused by faults to the greatest extent after the faults occur, and cannot avoid the occurrence of faults. Especially for the lines operating in grassland forest areas for a long time, it is very difficult to detect fires caused by tree-line connection or continuous heat accumulation due to the increasingly deteriorated insulation of the lines in the early stage of fault occurrence. Summary of the Invention

[0004] In order to solve the problem that the current single-phase grounding fault monitoring method for distribution network lines across grasslands can only reduce line electrical faults by quickly isolating single-phase grounding faults and cannot detect line faults in advance, the present invention provides a wildfire warning method for improving the grounding judgment ability of grassland distribution lines, and the method includes:

[0005] S1. Install monitoring devices at key nodes of the distribution network line to obtain the topology map of the distribution network;

[0006] S2. Based on the monitoring devices, obtain the line oscillogram file, screen the line oscillogram file, and obtain the zero-sequence voltage oscillogram file;

[0007] S3. Group the zero-sequence voltage oscillogram files based on the distribution trunk line to obtain several first oscillogram file groups, obtain the first time of the first oscillogram file group, obtain potential hazard events based on the first time and the first preset time range, and obtain the potential hazard oscillogram files of the potential hazard events;

[0008] S4. Group the potential hazard oscillogram files based on a preset zero-sequence voltage range and a second preset time range to obtain several second oscillogram file groups, obtain out-of-region potential hazard points and in-region potential hazard points based on the oscillogram data of the second oscillogram file groups, and mark the out-of-region potential hazard points and the in-region potential hazard points;

[0009] S5. Based on the topological graph, the off-site potential hazard points, and the on-site potential hazard points, obtain a number of potential hazard areas, and based on the potential hazard areas, obtain early warning information.

[0010] The on-site potential hazard points refer to the direction of electric energy of the current monitoring device being the outgoing direction, and the off-site potential hazard points refer to the direction of electric energy of the current monitoring device being the incoming direction.

[0011] The present invention takes the substation main station system as the carrier and the monitoring devices with the function of recording waves as the nodes. By uploading the wave recording files of each key node to the main station, based on the frequent instantaneous fault characteristics before the permanent ground fault occurs, that is, the zero-sequence voltage will increase significantly after the ground fault occurs, only obtain the wave recording files generated by the mutation or over-limit of the zero-sequence voltage; excavate the relatively hidden ground faults such as high-resistance grounding and tree-line connection of the distribution lines across the forest area, group the wave recording files of the same trunk line into one group, and classify the wave recording files within the same time range as potential hazard events. According to the magnitude and duration of the zero-sequence voltage, use different grounding protection algorithms to process the potential hazard events, judge the potential hazard direction, so as to obtain the potential hazard areas, and use the number of fault sections counted per unit time to represent the crisis degree of the early warning, which can detect the potential forest fire hazards in the early stage of the fault and effectively reduce the forest fires caused by power failures. Further, in S4, if the preset zero-sequence voltage range is the first voltage range and the second preset time range is the first time range, then based on the grouping of the second wave recording files, obtain the first zero-sequence voltage mutation point, based on the first zero-sequence voltage mutation point, obtain the zero-sequence voltage and zero-sequence current within the first preset period, obtain the voltage value of the zero-sequence voltage and the current value of the zero-sequence current, and based on the voltage value and the current value, obtain the off-site potential hazard points and the on-site potential hazard points.

[0012] Further, in S4, if the preset zero-sequence voltage range is the second voltage range and the second preset time range is the second time range, then based on the grouping of the second wave recording files, obtain the second zero-sequence voltage mutation point, based on the second zero-sequence voltage mutation point, obtain a number of sampling points within the second preset period, obtain the zero-sequence active power and zero-sequence reactive power of the sampling points, add the zero-sequence active power and the zero-sequence reactive power to obtain the total zero-sequence active power and the total zero-sequence reactive power, and based on the total zero-sequence active power and the total zero-sequence reactive power, obtain the off-site potential hazard points and the on-site potential hazard points.

[0013] Accumulate the zero-sequence active power and zero-sequence reactive power of a single sampling point respectively, and integrate the subtle grounding fault characteristics of high-resistance grounding within the unit time, so as to reveal the hidden and potential grounding characteristics and more accurately judge the potential hazard direction.

[0014] Further, in S5, based on the potential hazard area and a preset rule, warning information is obtained. The preset rule is as follows: different scoring periods are preset, and each scoring period corresponds to a warning threshold and a warning level; based on a preset score and the scoring period, the potential hazard score of the potential hazard area is obtained, based on the potential hazard score and the warning threshold, the warning level is obtained, and based on the warning level, the warning information is obtained.

[0015] Setting different warning periods can provide fault warnings of different degrees, improving the timeliness and accuracy of warnings.

[0016] Considering the general line load balance, the zero-sequence voltage will be lower than 500V. When it is greater than 1000V, there may be a ground fault. If the duration is less than 40ms (less than two cycles), it is an instantaneous ground fault. Generally, it is caused by branches occasionally overlapping the line under the action of wind, and there is a situation where high-voltage arcs ignite trees. For medium and low-resistance ground faults, the zero-sequence voltage is generally above 12kV. If the zero-sequence voltage is between 1 and 8kV and exists for a long time, it is a high-resistance ground fault. If such a situation exists in the forest, although the fault current is small, long-term heat accumulation still poses a risk of igniting shrubs. Therefore, the present method considers the following two ranges for classification.

[0017] Further, the first voltage range is greater than 1kV, and the first time range is less than 40ms; the second voltage range is greater than or equal to 1kV and less than or equal to 8kV, and the second time range is the time from the start of recording the potential hazard recording file to the end of recording.

[0018] Further, the specific steps for obtaining the out-of-area potential hazard point and the in-area potential hazard point based on the voltage value and the current value include: obtaining the first-order difference value of the voltage value. If both the first-order difference value and the current value are positive or negative, the monitoring device is an out-of-area potential hazard point. If the first-order difference value and the current value are not both positive or negative, the monitoring device is an in-area potential hazard point.

[0019] Further, the specific steps for obtaining the out-of-area potential hazard point and the in-area potential hazard point based on the total zero-sequence active power and the total zero-sequence reactive power include: if the total zero-sequence active power is less than 0, the monitoring device is an in-area potential hazard point. If the total zero-sequence active power is greater than or equal to 0 and the total zero-sequence reactive power is less than 0, the monitoring device is an out-of-area potential hazard point.

[0020] The zero-sequence power direction method determines a fault by calculating the power criterion within a unit time for a single sampling point, but for high-resistance ground faults, the fault current is small, and the power calculated from a single sampling point is small and cannot meet the power criterion requirements. Therefore, the present method judges the fault direction by integrating the sampling points within a unit time to improve the accuracy of judgment.

[0021] Furthermore, the first calculation formula for obtaining the total zero-sequence active power is:

[0022]

[0023] The second calculation formula for obtaining the total zero-sequence reactive power is:

[0024]

[0025] in, represents the zero sequence voltage, Represents the zero sequence current, represents the zero-sequence voltage angle, represents the zero-sequence current angle, ∠Z represents the zero-sequence impedance angle, P0total represents the total zero-sequence active power, Q0total represents the total zero-sequence reactive power, i represents the i-th sampling point, and n represents the number of sampling points.

[0026] Furthermore, if the effective value of the zero-sequence current of the hidden danger point in the area is less than a preset current threshold, the mark of the hidden danger point in the area is deleted.

[0027] To ensure the accuracy of the judgment results, a lower limit value of zero-sequence current is set. The maximum effective value of the zero-sequence current of the waveform judged as a ground fault in the area should be greater than this value. If it is less than this value, it will not participate in the early warning, reducing the problem of accuracy not meeting the requirements due to the zero-sequence current being too small, thereby affecting the algorithm judgment.

[0028] Considering that branches on both sides of the line in the forest area will grow in spring, the newly grown branches may overlap the line and cause line failure. This method predicts the growth direction of the branches in real time through continuous growth images of the branches within a certain time range. The real-time growth rate of the current branches is obtained through the length of the branches grown, the changing branch diameter and the growth time of the current branches of different types. The growth rate of different types of branches at different diameters is then inferred. The maximum growth length is predicted by combining the growth rate and diameter. The growth direction and maximum growth length are comprehensively considered to determine whether the branches will overlap the line, thereby issuing an early warning to the branch area and pruning it, reducing the possibility of line failure, thereby further reducing the possibility of wildfires.

[0029] Furthermore, the method further comprises:

[0030] Obtain forest area images, obtain the first distance between branches and lines based on the forest area images, and obtain dangerous areas based on a preset distance range and the first distance; obtain dangerous branches in the dangerous areas, obtain the tip areas of the dangerous branches, obtain the branch diameters of the tip areas, obtain branch images of the dangerous branches within a preset time range, and obtain the growth diameter based on the branch images; obtain the first line of the branch images, and predict the growth direction of the dangerous branches based on the first line; obtain the growth length based on the first line, obtain the first growth speed based on the growth diameter, the growth length, and the preset time range, and preset the second growth speed of the dangerous branches under different branch diameters based on the first growth speed; predict the longest growth lengths of different types of branches based on the second growth speed and the branch diameter; and obtain a danger warning based on a preset dangerous direction, the longest growth length, and the growth direction.

[0031] Only obtain the branches in the dangerous areas, reduce the number of branches to be monitored, and achieve a faster warning response; obtain the real-time growth conditions of different types of branches at different time points in continuous images as they grow, change with the weather, and change with the growth environment, obtain the real-time growth direction, real-time growth speed, and real-time growth diameter of different types of branches through image comparison, and give priority to the longest growth length of the branches along a straight line in the current direction. The current straight line direction is the longest growth length when the branches do not change. If the currently predicted length exceeds the dangerous area, a warning is issued, reducing the situation where it is difficult to calculate the length after the morphological appearance of the branches changes later and the warning is not timely. It comprehensively considers the changes in the types, volume sizes, and shapes of the branches, and even if affected by human and animal interference, it can obtain the changes according to the image changes, thereby achieving accurate danger warnings.

[0032] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0033] 1. The present invention uses the substation master station system as a carrier and monitoring equipment with a recording function as a node. By uploading the recording files of each key node to the main station, based on the frequent transient fault characteristics before the permanent grounding fault occurs, the zero-sequence voltage will increase significantly after the grounding fault occurs, so only the recording files generated by the zero-sequence voltage mutation or exceeding the limit are obtained; the more hidden grounding faults such as high-resistance grounding and tree-line overlap of distribution lines crossing forest areas are explored, the recording files of the same trunk line are grouped, and the recording files of the same time range are classified as hidden danger events. Different grounding protection algorithms are used to process the hidden danger events according to the size and duration of the zero-sequence voltage, and the hidden danger direction is determined to obtain the hidden danger area. The fault section count per unit time is used to indicate the crisis level of the early warning, so that forest fire hazards can be discovered in the early stage of the fault, effectively reducing forest fires caused by power failures.

[0034] 2. Accumulate the zero-sequence active power and zero-sequence reactive power of a single sampling point separately. By integrating the subtle grounding fault characteristics of high-resistance grounding within a unit time, the hidden and potential grounding characteristics are revealed, and the direction of the hidden danger is judged more accurately.

[0035] 3. Based on the hidden danger areas and preset rules, early warning information is obtained and different early warning cycles are set, which can provide different degrees of fault early warning and improve the timeliness and accuracy of the early warning.

[0036] 4. Obtain danger warnings based on branch diameter, growth direction, and growth rate. By predicting the growth direction, growth rate, and maximum length of branches, it is determined whether they will overlap with the line, thereby issuing an early warning to the branch area and pruning it to reduce line failures, thereby further reducing the occurrence of wildfires. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation of the embodiments of the present invention;

[0038] Figure 1 This is a flow chart of a wildfire early warning method for improving the grounding analysis and judgment capability of grassland power distribution lines in the present invention;

[0039] Figure 2 It is a flow chart for obtaining hidden danger points outside the area and hidden danger points inside the area;

[0040] Figure 3 It is a schematic diagram showing that the first-order difference value and the current value are inverse in value in the present invention. DETAILED DESCRIPTION

[0041] To better understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0042] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described within the scope here. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0043] Embodiment 1

[0044] Reference Figures 1 - 3 , this embodiment provides a wildfire warning method for improving the grounding judgment ability of grassland distribution lines, and the method includes:

[0045] S1. Install monitoring equipment at key nodes of the distribution network line to obtain the topology diagram of the distribution network; in this embodiment, the monitoring equipment can be a primary-secondary integrated terminal device with a wave recording function, and the primary-secondary integrated terminal device can identify electrical characteristic quantities (zero-sequence voltage) and generate wave recording files due to the mutation of over-limit wave recording;

[0046] The key nodes can be substation outlet points, branch line connection points, line section switches, important user access points, cable and overhead line conversion points, etc. Since the above positions are key points for power distribution, current shunting, fault isolation, etc., which are related to power supply reliability and balance, and some nodes involve special guarantee requirements or are prone to faults and difficult to repair, they are crucial for the smooth operation of the distribution network, so they are selected as key nodes.

[0047] S2. Based on the line wave recording file obtained by the monitoring equipment, screen the line wave recording file to obtain a zero-sequence voltage wave recording file; when the distribution network is operating normally, the zero-sequence voltage is very small and almost zero. After a grounding fault occurs, the zero-sequence voltage will increase significantly. Therefore, only obtain the wave recording files generated due to the mutation or over-limit of the characteristic values of the zero-sequence voltage channel, and the over-limit value can be set to 0.5 - 1 kV, which can be specifically determined according to the line load imbalance degree and the expected degree of identifying high resistance.

[0048] The wave recording file generally contains 8 analog quantity data channels and 1 status quantity data channel. The 8 analog quantity data channels are the voltages and currents of phases A, B, and C, as well as zero-sequence voltage and zero-sequence current respectively. The characteristic value of the zero-sequence voltage channel refers to the sampled value of the zero-sequence voltage recorded in the wave recording file.

[0049] S3. Group the zero-sequence voltage recording files based on the distribution main line to obtain several first groups of recording files. Obtain the first time of the first group of recording files. Based on the first time and the first preset time range, obtain potential hazard events, and obtain the hazard recording files of the potential hazard events. For example, if grouping is performed according to the same main line of the same substation, and it is found that there are zero-sequence voltage recording files on the same main line within a certain time range (such as 10 s) after grouping, then the waveform files of the same main line are classified as a primary fault potential hazard event. Perform preliminary screening and analysis on the recording files of the primary fault potential hazard event.

[0050] S4. Based on the preset zero-sequence voltage range and the second preset time range, group the hazard recording files to obtain several second groups of recording files. Based on the recording data of the second groups of recording files, obtain out-of-region potential hazard points and in-region potential hazard points, and mark the out-of-region potential hazard points and the in-region potential hazard points. Classify and analyze the waveforms according to the magnitude of the zero-sequence voltage and the duration of the zero-sequence voltage to judge the potential hazard direction more accurately.

[0051] Among them, in S4, if the preset zero-sequence voltage range is the first voltage range and the second preset time range is the first time range, then obtain the first zero-sequence voltage mutation point based on the second group of recording files. Based on the first zero-sequence voltage mutation point, obtain the zero-sequence voltage and zero-sequence current within the first preset period. For example, according to the zero-sequence voltage and zero-sequence current within the first half-wave period after the zero-sequence voltage mutation point, obtain the voltage value of the zero-sequence voltage and the current value of the zero-sequence current. Based on the voltage value and the current value, obtain the out-of-region potential hazard points and the in-region potential hazard points. Analyze the instantaneous ground fault.

[0052] Among them, the specific steps of obtaining the out-of-region potential hazard points and the in-region potential hazard points based on the voltage value and the current value include: obtain the first-order difference value of the voltage value. If both the first-order difference value and the current value are positive or negative, then the monitoring device is an out-of-region potential hazard point. If the first-order difference value and the current value are not both positive or negative, then the monitoring device is an in-region potential hazard point. Refer to Figure 3 , obtain the waveform diagrams of the first-order difference value and the current value. If the waveforms are opposite within the same time, then mark it as an in-region potential hazard point. Similarly, if they are the same, then it is an out-of-region potential hazard point.

[0053] Among them, in S4, if the preset zero-sequence voltage range is the second voltage range and the second preset time range is the second time range, then based on the second grouped oscillogram files, second zero-sequence voltage mutation points are obtained. Based on the second zero-sequence voltage mutation points, a number of sampling points within a second preset period are obtained. The zero-sequence active power and zero-sequence reactive power of the sampling points are obtained. For example, the zero-sequence active power and zero-sequence reactive power of the sampling points two cycles after the zero-sequence voltage mutation point are obtained. The zero-sequence active power and the zero-sequence reactive power are added together to obtain the total zero-sequence active power and the total zero-sequence reactive power. Based on the total zero-sequence active power and the total zero-sequence reactive power, the out-of-region potential trouble points and the in-region potential trouble points are obtained. Analysis is carried out for high-resistance grounding.

[0054] Among them, the specific steps for obtaining the out-of-region potential trouble points and the in-region potential trouble points based on the total zero-sequence active power and the total zero-sequence reactive power include:

[0055] If the total zero-sequence active power is less than 0, then the monitoring device is an in-region potential trouble point. If the total zero-sequence active power is greater than or equal to 0 and the total zero-sequence reactive power is less than 0, then the monitoring device is an out-of-region potential trouble point.

[0056] Among them, if the effective value of the zero-sequence current of the in-region potential trouble point is less than the preset current threshold, then the mark of the in-region potential trouble point is deleted.

[0057] Among them, the first voltage range is greater than 1 kV and the first time range is less than 40 ms; the second voltage range is greater than or equal to 1 kV and less than or equal to 8 kV, and the second time range is the time from the start of recording of the trouble oscillogram file to the end of recording.

[0058] S5. Based on the topology diagram, the out-of-region potential trouble points and the in-region potential trouble points, a number of potential trouble regions are obtained. Based on the potential trouble regions, warning information is obtained. For example, the primary and secondary integrated terminal device of switch 3 is marked as an in-region potential trouble point (i.e., the direction of power transmission), and the primary and secondary integrated terminal devices of switches 2 and 4 are marked as out-of-region potential trouble points (i.e., the direction of power input). According to the topology diagram, the line regions in front of switches 2 and 4 and behind switch 3 are marked as potential trouble regions.

[0059] Among them, in S5, based on the potential trouble regions and preset rules, warning information is obtained. The preset rules are as follows:

[0060] Different scoring periods are preset, and each scoring period corresponds to a warning threshold and a warning level; for example, long-term period, medium-term period, and short-term period are preset, and each period corresponds to a preset threshold, and the warning levels are set as general, serious, and critical in sequence;

[0061] Based on the preset score and the scoring period, obtain the hidden danger score of the hidden danger area. Based on the hidden danger score and the warning threshold, obtain the warning level. Based on the warning level, obtain the warning information. For example, assign scores to each hidden danger area, count the number of hidden danger areas in each period, so as to obtain the total score, and compare it with the preset threshold. If it exceeds, issue a warning.

[0062] In the scenario of judging the grounding fault of the line across the forest area and grassland, instantaneous grounding faults and high-resistance grounding faults are relatively common fault types that have a greater impact on the safe and stable operation of the system. Among them, the instantaneous grounding fault is aimed at the fault scenario of the frequent contact between the tree line and the line under the action of wind, and the high-resistance grounding fault is aimed at the fault scenario of the line insulation deteriorating for a long time and continuously accumulating heat to cause a wildfire. The fault discrimination has a clear direction. For these two types of faults, the first half-wave method and the zero-sequence power integration method are respectively used for judgment, which is the result of comprehensive consideration based on the fault characteristics, detection principles and actual application requirements, and they each have unique advantages.

[0063] At the beginning of the protection startup, the present invention can select a suitable grounding judgment algorithm through waveform characteristics (the first half-wave method is used for instantaneous grounding faults, and the zero-sequence power integration method is used for high-resistance grounding faults), improving the accuracy of grounding fault discrimination.

[0064] Instantaneous grounding faults are often caused by occasional contact between branches and the line under the action of wind, and have the characteristic of short duration, generally less than 40ms. At the moment of fault occurrence, the transient capacitance current characteristic is obvious. When the free component and the forced component of the transient capacitance current are single-phase grounded at the moment when the phase voltage is close to the maximum value, the transient capacitance current is much larger than the transient inductance current flowing through the arc suppression coil, and the transient inductance current can be ignored. This makes the first half-wave of the first cycle of the transient zero-sequence current of the faulty line opposite to that of the non-faulty line. Therefore, the present invention utilizes this characteristic of the first half-wave method to quickly capture the characteristics of instantaneous grounding faults. In the initial stage of fault occurrence, only need to analyze the zero-sequence voltage and current within the first half-wave cycle after the zero-sequence voltage mutation point, obtain the voltage value and current value, and determine whether the monitoring device is an external hidden danger point or an internal hidden danger point by judging the positive and negative relationship between the first-order difference value of the voltage value and the current value, realizing the rapid judgment of the fault direction, responding more quickly to instantaneous faults, being able to detect potential fault hidden dangers in time, and reducing the situation that may be ignored due to the short fault duration. At the same time, this method focuses on the transient characteristics at the moment of fault occurrence, avoiding the interference of other factors in the steady state process and improving the accuracy of fault judgment.

[0065] A high-resistance grounding fault refers to a situation where the feeder is grounded via non-metallic conductive media such as grass, concrete, branches, etc. The fault current is small, the zero-sequence power is small, and the fault characteristics are weak. However, the fault will persist and may cause serious consequences. Traditional detection methods based on traveling wave waveforms, high-order harmonic components, and directly using the zero-sequence active power and zero-sequence reactive power at a single sampling point have limitations in detecting high-resistance grounding faults and are difficult to accurately discriminate.

[0066] The present invention adopts the zero-sequence power integration method, which is an upgrade and innovation based on the zero-sequence power direction method. By integrating and accumulating the weak zero-sequence power within a unit time, the zero-sequence active power and zero-sequence reactive power at a single sampling point are respectively accumulated, and the subtle grounding fault characteristics of high-resistance grounding are integrated within a unit time, thereby revealing the hidden and potential grounding characteristics. By calculating the total zero-sequence active power and the total zero-sequence reactive power and judging the potential fault points outside and inside the zone based on their numerical relationships, the fault direction can be more accurately judged, effectively overcoming the problem of difficult detection of high-resistance grounding faults, improving the detection sensitivity and accuracy for such faults. Integrating and accumulating the weak zero-sequence power within a unit time during high-resistance grounding faults can more quickly and accurately detect high-resistance grounding faults caused by insulation deterioration, solving the problem that the traditional zero-sequence power direction method is limited by the too small zero-sequence power of high-resistance grounding faults and cannot make discrimination.

[0067] Embodiment 2

[0068] Based on Embodiment 1, in this embodiment, the first calculation formula for obtaining the total zero-sequence active power is:

[0069]

[0070] The second calculation formula for obtaining the total zero-sequence reactive power is:

[0071]

[0072] Wherein, represents the zero-sequence voltage, represents the zero-sequence current, represents the zero-sequence voltage angle, represents the zero-sequence current angle, ∠Z represents the zero-sequence impedance angle, P0 total represents the total zero-sequence active power, Q0 total represents the total zero-sequence reactive power, i represents the i-th sampling point, and n represents the number of sampling points.

[0073] Improve the zero-sequence power direction method. Use the integration of zero-sequence active power and zero-sequence reactive power within a unit time to replace the method of directly using the zero-sequence active power and zero-sequence reactive power at a single sampling point. Amplifying the grounding fault characteristics is beneficial to more sensitively detecting high-resistance grounding faults.

[0074] Embodiment 3

[0075] Based on the above embodiments, in this embodiment, the method further includes:

[0076] Obtain a forest area image, obtain a first distance between a branch and a line based on the forest area image, and obtain a dangerous area based on a preset distance range and the first distance; for example, collect an image around the line through a collection device such as a drone, obtain the distance between the branch and the line, and the distance can include a lateral distance and a longitudinal distance, and screen the area where the branch is close to the line according to the distance;

[0077] Obtain dangerous branches in the dangerous area, obtain the tip area of the dangerous branches, obtain the branch diameter of the tip area, obtain branch images of the dangerous branches within a preset time range, and obtain a growth diameter based on the branch images; obtain a first line of the branch images, and predict the growth direction of the dangerous branches based on the first line; for example, obtain continuous growth images of the dangerous branches within a week, obtain change data of the branch diameter through the continuous growth images, extract the lines of the growth images, and obtain its current real-time growth direction through the comparison of the lines;

[0078] Obtain a growth length based on the first line, obtain a first growth speed based on the growth diameter, the growth length, and the preset time range, and preset a second growth speed of the dangerous branches under different branch diameters based on the first growth speed; for example, through the comparison of the lines, obtain the length of the corresponding growth of the dangerous branches within a week in the current growth environment, predict the growth speed at the current diameter through the change data of the diameter and the growth length, and then predict the growth speed under different diameters in the later stage by combining the relevant data of this type of branch (such as a deep learning model pre-trained according to the growth data of the branch);

[0079] Predict the longest growth length of different types of branches based on the second growth speed and the branch diameter; for example, preset the minimum diameter that can grow for different types, and comprehensively predict its longest growth length through the minimum diameter, the second growth speed, and the current diameter;

[0080] Obtain a danger warning based on a preset dangerous direction, the longest growth length, and the growth direction. For example, first determine whether the growth direction is within the preset dangerous direction range. If so, then determine whether it will exceed the dangerous area according to its longest growth length. If so, issue a danger warning, so as to perform branch pruning in advance and reduce line failures caused by branches overlapping the line.

[0081] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0082] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A wildfire warning method for improving the grounding judgment ability of grassland distribution lines, characterized in that The method includes: S1. Install monitoring devices at key nodes of the distribution network line to obtain the topology diagram of the distribution network; S2. Obtain the line wave recording file based on the monitoring device, screen the line wave recording file, and obtain the zero-sequence voltage wave recording file; S3. Group the zero-sequence voltage wave recording files based on the distribution main line to obtain several first wave recording file groups, obtain the first time of the first wave recording file group, obtain potential hazard events based on the first time and the first preset time range, and obtain the potential hazard wave recording files of the potential hazard events; S4. Group the potential hazard wave recording files based on the preset zero-sequence voltage range and the second preset time range to obtain several second wave recording file groups, obtain the out-of-region potential hazard points and in-region potential hazard points based on the wave recording data of the second wave recording file groups, and mark the out-of-region potential hazard points and the in-region potential hazard points; S5. Obtain several potential hazard regions based on the topology diagram, the out-of-region potential hazard points, and the in-region potential hazard points, and obtain early warning information based on the potential hazard regions.

2. The wildfire warning method for enhancing the grounding judgment ability of grassland distribution lines according to claim 1, characterized in that, In S4, if the preset zero-sequence voltage range is the first voltage range and the second preset time range is the first time range, obtain the first zero-sequence voltage mutation point based on the second wave recording file group, obtain the zero-sequence voltage and zero-sequence current within the first preset period based on the first zero-sequence voltage mutation point, obtain the voltage value of the zero-sequence voltage and the current value of the zero-sequence current, and obtain the out-of-region potential hazard points and the in-region potential hazard points based on the voltage value and the current value.

3. The wildfire warning method for enhancing the grounding judgment ability of grassland distribution lines according to claim 2, characterized in that, In S4, if the preset zero-sequence voltage range is the second voltage range and the second preset time range is the second time range, obtain the second zero-sequence voltage mutation point based on the second wave recording file group, obtain several sampling points within the second preset period based on the second zero-sequence voltage mutation point, obtain the zero-sequence active power and zero-sequence reactive power of the sampling points, add the zero-sequence active power and the zero-sequence reactive power to obtain the total zero-sequence active power and the total zero-sequence reactive power, and obtain the out-of-region potential hazard points and the in-region potential hazard points based on the total zero-sequence active power and the total zero-sequence reactive power.

4. A wildfire early warning method for improving grassland power distribution line grounding analysis and judgment capabilities according to claim 1, characterized in that: In S5, obtain early warning information based on the potential hazard regions and preset rules, and the preset rules are: Preset different scoring periods, and each scoring period corresponds to a warning threshold and a warning level; Obtain the potential hazard score of the potential hazard region based on the preset score and the scoring period, obtain the warning level based on the potential hazard score and the warning threshold, and obtain the early warning information based on the warning level.

5. A wildfire warning method for improving the grounding judgment ability of grassland distribution lines according to claim 3, characterized in that, The first voltage range is greater than 1 kV, and the first time range is less than 40 ms; the second voltage range is greater than or equal to 1 kV and less than or equal to 8 kV, and the second time range is the time from the start of wave recording to the end of wave recording of the potential hazard wave recording file.

6. The wildfire warning method for enhancing the grounding judgment ability of grassland distribution lines according to claim 2, characterized in that, The specific steps of obtaining the out-of-region potential hazard points and the in-region potential hazard points based on the voltage value and the current value include: Obtain the first-order difference value of the voltage value. If both the first-order difference value and the current value are positive or negative, the monitoring device is a potential hazard point outside the area. If the first-order difference value and the current value are not both positive or negative, the monitoring device is a potential hazard point inside the area.

7. A wildfire early warning method for improving grassland power distribution line grounding analysis and judgment capabilities according to claim 3, characterized in that: Based on the total zero-sequence active power and the total zero-sequence reactive power, the specific steps for obtaining the potential hazard point outside the area and the potential hazard point inside the area are as follows: If the total zero-sequence active power is less than 0, the monitoring device is a potential hazard point inside the area. If the total zero-sequence active power is greater than or equal to 0 and the total zero-sequence reactive power is less than 0, the monitoring device is a potential hazard point outside the area.

8. A wildfire warning method for improving the grounding judgment ability of grassland distribution lines according to claim 3, characterized in that, The first calculation formula for obtaining the total zero-sequence active power is: The second calculation formula for obtaining the total zero-sequence reactive power is: Among them, represents the zero-sequence voltage, represents the zero-sequence current, represents the zero-sequence voltage angle, represents the zero-sequence current angle, ∠Z represents the zero-sequence impedance angle, P0 total represents the total zero-sequence active power, Q0 total represents the total zero-sequence reactive power, i represents the i-th sampling point, and n represents the number of sampling points.

9. A wildfire warning method for enhancing the grounding judgment ability of grassland distribution lines according to claim 3, characterized in that, If the effective value of the zero-sequence current of the potential hazard point inside the area is less than the preset current threshold, delete the mark of the potential hazard point inside the area.

10. A wildfire warning method for improving the grounding judgment ability of grassland distribution lines according to claim 1, characterized in that, The method further includes: Obtain a forest area image, obtain the first distance between the branches and the line based on the forest area image, and obtain a dangerous area based on the preset distance range and the first distance; Obtain the dangerous branches in the dangerous area, obtain the tip area of the dangerous branches, obtain the branch diameter of the tip area, obtain the branch images of the dangerous branches within a preset time range, and obtain the growth diameter based on the branch images; Obtain the first line of the branch image, and predict the growth direction of the dangerous branches based on the first line; Obtain the growth length based on the first line, obtain the first growth rate based on the growth diameter, the growth length, and the preset time range, and preset the second growth rate of the dangerous branches under different branch diameters based on the first growth rate; Predict the longest growth length of different types of branches based on the second growth rate and the branch diameter; Obtain a danger warning based on the preset danger direction, the longest growth length, and the growth direction.

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