Overhead line tree touch fault simulation method

Abstract

The invention belongs to the technical field of power system power distribution network relay protection, and provides an overhead line tree touch fault simulation method, which comprises the following steps of: 1, establishing a circuit model based on physical characteristics of a current path when an overhead line is in contact with a tree; 2, dividing a physical process according to a tree medium state change rule in a tree touch fault development process, and establishing a resistivity dynamic model of each stage; 3, respectively calculating the correlation of the analog signals by using a Pearson's correlation coefficient method; step 4, constructing a criterion based on the average correlation coefficient # imgabs0 # in the step 3; according to the method, through full-stage dynamic modeling and refined simulation, the time-varying characteristic of state change of a tree medium is fully considered, and the physical authenticity of simulation and the continuity of stage transition are remarkably improved; meanwhile, multi-stage correlation verification and reliability criteria are introduced, and the simulation precision is quantified by using a Pearson's correlation coefficient method, so that the credibility and engineering applicability of a touch tree fault simulation result are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection for distribution networks in power systems, and specifically relates to a method for simulating overhead line tree-touching faults. Background Art

[0002] With the increase in the number of intersections between overhead transmission lines and vegetation areas, tree-touching faults on the lines occur frequently, easily triggering accidents such as tripping and wildfires, threatening the safety of the power grid and the ecological environment.

[0003] Existing high-resistance grounding fault models are difficult to effectively characterize the physical process in which the impedance of a tree decreases dynamically with the extension of the contact time, resulting in problems such as insufficient sensitivity and action delay in detection algorithms based on steady-state characteristics, becoming a technical bottleneck restricting the prevention of wildfires and rapid isolation of faults in distribution networks.

[0004] Therefore, it is urgent to conduct in-depth research on the dynamic evolution characteristics of tree-touching faults and construct a dynamic model of tree-touching faults that integrates the coupled effects of electro-thermal-humidity multi-physical fields to break through the limitations of existing detection technologies. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for simulating overhead line tree-touching faults, which solves the problem of simulation distortion caused by the traditional tree-touching fault model being unable to accurately characterize the time-varying characteristics of the fault current path due to ignoring the dynamic physical state evolution of the tree medium.

[0006] In a first aspect, the present invention provides a method for simulating overhead line tree-touching faults, including the following steps: Step 1: Based on the physical characteristics of the current path when an overhead line contacts a tree, establish a series equivalent circuit model composed of an arc resistance R a , a contact resistance R c , and a tree body resistance R v ; through the series coupling of the three, construct a physical model of the overhead line tree-touching fault to achieve a quantitative characterization of the fault current path; Step 2: According to the physical state change law of the tree medium during the development process of the tree-touching fault, divide it into four physical processes: a contact stage, a moisture evaporation stage, a carbonization stage, and a fire stage; establish a dynamic correlation model between the resistivity and the fault state, denoted as , , , , R a to drive the arc resistance R c , the contact resistance R vThe dynamic changes are used to achieve a refined simulation of the whole process of overhead line tree contact faults; Step 3: Use the Pearson correlation coefficient method to calculate the contact stage of the simulated signal , the moisture evaporation stage , the carbonization stage , the open fire stage and the corresponding contact stage of the measured signal , the moisture evaporation stage , the carbonization stage , the open fire stage The correlation between them is denoted as ; Calculate the average correlation coefficient of the contact stage, moisture evaporation stage and carbonization stage ; Step 4: Based on the average correlation coefficient in Step 3 Construct a judgment basis: When the average correlation coefficient Satisfies , the simulation of the overhead line tree contact fault signal is accurate; otherwise, the simulation of the overhead line tree contact fault signal is inaccurate; is the set threshold.

[0007] Preferably, the arc resistance R a , the contact resistance R c and the tree body resistance R v in Step 1 are as follows: The arc resistance R a is calculated as follows: ; In the formula, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median value at which the arc voltage changes from the power supply voltage to 0, i f is the fault current flowing through the tree trunk at any time, and its formula is as follows: ; In the formula, u b is the voltage on the boundary hemisphere of the breakdown area with a radius of ; Its formula includes: ; In the formula, is the voltage on the tree, is the dielectric critical breakdown field strength; Contact resistance R c It is calculated as follows: ; In the formula, is the resistivity of the tree trunk, is the radius of the breakdown area, is a higher-order infinitesimal of ; The resistance of the tree body R v It is calculated as follows: ; In the formula, S is the cross-sectional area of the tree trunk, ρ is the resistivity of the tree trunk, h is the height of the tree trunk.

[0008] Preferably, the segmentation in step 2 is as follows: During the time period is the contact stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 0 is the resistivity of the medium at the ambient temperature, T 0 is the ambient temperature, T is the temperature of the tree trunk, k m is the resistivity correction coefficient, k A is a constant related to the material; During the time period is the moisture evaporation stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 10 is the final value of the resistivity in the contact stage, k n is the resistivity correction coefficient, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of the water content of the tree trunk; The water content of the tree trunk is: ; In the formula, k e is the water content amplitude coefficient; During the time period is the carbonization stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 20 are respectively the final values of the resistivity in the moisture evaporation stage, is the carbonization control coefficient, t 30 is the initial moment of the carbonization stage; During the time period is the open fire stage, and the resistivity formula is as follows: ; In the formula, is the attenuation DC component control coefficient, k r1 is the amplitude coefficient of the attenuation DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle; The resistivity formula for the tree-touching fault is as follows: ; In the formula, is the resistivity in the contact stage, is the resistivity in the moisture evaporation stage, is the resistivity in the carbonization stage, is the resistivity in the open fire stage.

[0009] Preferably, the calculation formula for the Pearson correlation coefficient in step 3 is: ; In the formula: x is the analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the analog signal and the measured signal; , are the mean and variance of the analog signal; , are the mean and variance of the measured signal; The average correlation coefficients for the contact stage, moisture evaporation stage, and carbonization stage The calculation formula is: ; If , then the simulation of the overhead line tree-line contact fault signal is accurate; otherwise, the simulation of the overhead line tree-line contact fault signal is inaccurate; is the set threshold.

[0010] In a second aspect, the present invention provides an overhead line tree contact fault simulation device, which is applied to the above-mentioned overhead line tree contact fault simulation method, and includes: Circuit model construction module: Based on the physical characteristics of the current path when the overhead line contacts the tree, construct a series equivalent circuit model composed of an arc resistance R a , contact resistance R c , and tree body resistance R v ; Fault stage division and resistivity dynamic correlation module: According to the physical state change law of the tree medium during the development of the tree contact fault, divide the fault process into four physical processes: contact stage, water evaporation stage, carbonization stage, and open fire stage, and establish a dynamic correlation model between resistivity and fault state; Signal simulation and correlation calculation module: Use the outputs of the circuit model construction module and the fault stage division and resistivity dynamic correlation module to simulate the overhead line tree contact fault signal, and calculate the correlation between the simulated signal and the measured signal in each stage using the Pearson correlation coefficient method; Simulation accuracy judgment module: Based on the output of the signal simulation and correlation calculation module, construct a judgment basis. When the average correlation coefficient meets the set threshold , it is determined that the simulation of the overhead line tree contact fault signal is accurate; otherwise, it is determined that the simulation is inaccurate; User interface and data management module: Provide a user interface, allowing users to input parameters, view simulation results, adjust thresholds, etc., and manage data storage and retrieval during the simulation process.

[0011] In a third aspect, the present invention provides a processor configured to execute the above-mentioned overhead line tree contact fault simulation method.

[0012] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned overhead line tree contact fault simulation method is implemented.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Full-stage dynamic modeling and refined simulation: By establishing a series-coupled model of arc resistance, contact resistance, and tree body resistance, and combining the four-stage division of the physical state change of tree media (contact, water evaporation, carbonization, open fire), the present invention innovatively proposes a dynamic resistivity correlation model. This model fully considers the time-varying characteristics of physical parameters such as temperature, water content, and carbonization degree, and realizes the dynamic quantitative characterization of the fault current path. Compared with the traditional static model, it can more accurately simulate the whole process of the fault developing from the initial contact to the open fire, significantly improving the physical authenticity of the simulation and the continuity of the stage transition.

[0014] 2. Multi-stage correlation verification and reliability criterion: The present invention introduces the Pearson correlation coefficient method to calculate the local correlation between the simulated signal and the measured signal in four stages respectively, and constructs the average correlation coefficients in the three stages of contact, evaporation, and carbonization as a comprehensive criterion. This method not only avoids the one-sidedness of single-stage evaluation, but also quantifies the simulation accuracy through thresholds, making the verification process repeatable and objective. This criterion can effectively identify the stages with large simulation deviations, provide a clear direction for model optimization, and enhance the credibility and engineering applicability of the fault simulation results. Description of the Drawings

[0015] Figure 1 It is a flowchart of a method for simulating overhead line tree-touching faults of the present invention; Figure 2 It is a schematic diagram of a simulation model of a single-phase tree-touching fault of an overhead line in a 10 kV system without branches in an embodiment of the present invention; Figure 3 It is a schematic diagram of the tree-touching fault signal of the first actual measurement of the overhead line tree-touching fault in an embodiment of the present invention; Figure 4 It is a schematic diagram of the comparison between the simulated signal and the first actual measurement of the overhead line tree-touching fault simulation in an embodiment of the present invention; Figure 5 It is a schematic diagram of the tree-touching fault signal of the second actual measurement of the overhead line tree-touching fault in an embodiment of the present invention; Figure 6 It is a schematic diagram of the comparison between the simulated signal and the second actual measurement of the overhead line tree-touching fault simulation in an embodiment of the present invention. Detailed Embodiment

[0016] The following further describes in detail the embodiments of the present invention in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0017] The present invention provides a method for simulating overhead line tree-touching faults, as Figure 1 shown, specifically: Step 1. Based on the physical characteristics of the current path when the overhead line contacts the tree, establish an arc resistance Ra 、Contact resistance R c 、Tree body resistance R v A series equivalent circuit model composed of them; through the series coupling of the three, a physical model of the overhead line touching the tree fault is constructed to realize the quantitative characterization of the fault current path; Step 2: According to the physical state change law of the tree medium during the development of the tree-touching fault, divide it into four physical processes: the contact stage, the water evaporation stage, the carbonization stage, and the open fire stage; establish a dynamic correlation model between the resistivity and the fault state, denoted as , , , , driving arc resistance R a 、Contact resistance R c 、Tree body resistance R v The dynamic changes of to realize the refined simulation of the whole process of the overhead line touching the tree fault; Step 3: Use the Pearson correlation coefficient method to calculate the contact stage of the simulated signal respectively 、Water evaporation stage 、Carbonization stage 、Open fire stage And the corresponding contact stage of the measured signal 、Water evaporation stage 、Carbonization stage 、Open fire stage The correlation between them, denoted as ; Calculate the average correlation coefficient of the contact stage, the water evaporation stage and the carbonization stage ; Step 4: Based on the average correlation coefficient in Step 3 Construct a judgment basis: When the average correlation coefficient Satisfy When, the simulation of the overhead line tree-line contact fault signal is accurate; otherwise, the simulation of the overhead line tree-line contact fault signal is inaccurate; Is the set threshold.

[0018] As can be seen from the above, firstly, by establishing a series equivalent circuit model including arc resistance, contact resistance, and tree body resistance, and considering the four-stage division of the physical state change of the tree medium, the refined simulation of the whole process of the tree-touching fault is realized, significantly improving the accuracy and physical authenticity of the simulation. Secondly, the Pearson correlation coefficient method is used for multi-stage correlation verification, and a reliability criterion based on the average correlation coefficient is constructed, making the evaluation of the simulation accuracy more objective and repeatable, providing a clear direction for model optimization, and enhancing the credibility and engineering applicability of the fault simulation results.

[0019] Specifically, in step 1, the arc resistance R a , contact resistance R c , and tree body resistance R v are calculated as follows: The arc resistance R a is calculated as follows: ; In the formula, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median value at which the arc voltage changes from the power supply voltage to 0, i f is the fault current flowing through the tree trunk at any time, and its formula is as follows: ; In the formula, u b is the voltage on the boundary hemisphere of the breakdown area with a radius of ; its formula includes: ; In the formula, is the voltage on the tree, is the critical breakdown field strength of the medium; The contact resistance R c is calculated as follows: ; In the formula, is the resistivity of the tree trunk, is the radius of the breakdown area, is the higher-order infinitesimal of; The tree body resistance R v is calculated as follows: ; In the formula, S is the cross-sectional area of the tree trunk, ρ is the resistivity of the tree trunk, h is the height of the tree trunk.

[0020] As can be seen from the above, the above formula quantifies the arc resistance, contact resistance and tree body resistance precisely, considers key parameters such as arc voltage, power supply voltage, breakdown region voltage, tree trunk resistivity, cross-sectional area and height, provides a solid mathematical basis for constructing a physical model of overhead line tree-touching faults, realizes the quantitative characterization of the fault current path, thus significantly improving the accuracy and reliability of the simulation, and provides strong support for subsequent fault analysis and protection strategy formulation.

[0021] Specifically, the segmentation in step 2 is as follows: During the time period is the contact stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 0 is the resistivity of the medium at the ambient temperature, T 0 is the ambient temperature, T is the temperature of the tree trunk, k m is the resistivity correction coefficient, k A is a constant related to the material; During the time period is the water evaporation stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 10 is the final value of the resistivity in the contact stage, k n is the resistivity correction coefficient, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of the water content of the tree trunk; The water content of the tree trunk is: ; In the formula, k e is the water content amplitude coefficient; During the time period is the carbonization stage, and the formula for the resistivity of the tree trunk is as follows: ; In the formula, ρ 20They are the final values of the resistivity during the water evaporation stage, is the carbonization control coefficient, t 30 is the initial moment of the carbonization stage; During the time period is the open fire stage, and the resistivity formula is as follows: ; In the formula, is the decay DC component control coefficient, k r1 is the amplitude coefficient of the decay DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle; The resistivity formula for the tree-touching fault is as follows: ; In the formula, is the resistivity during the contact stage, is the resistivity during the water evaporation stage, is the resistivity during the carbonization stage, is the resistivity during the open fire stage.

[0022] As can be seen from the above, by introducing key variables such as temperature, water content, carbonization degree, and time, the above formula finely depicts the dynamic change of the tree trunk resistivity with the fault process, realizes the quantitative description of the resistivity in the whole process of the tree-touching fault, thus significantly improving the accuracy and refinement degree of the simulation, providing a more real and reliable physical basis for fault simulation and analysis, and helping to more deeply understand the dynamic evolution characteristics of the tree-touching fault.

[0023] Specifically, the calculation formula for the Pearson correlation coefficient in step 3 is: ; In the formula: x is the simulated signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; 、 are the mean and variance of the simulated signal; 、 are the mean and variance of the measured signal; The average correlation coefficients for the contact stage, water evaporation stage, and carbonization stage The calculation formula is: ; If , the simulation of the overhead line tree-line contact fault signal is accurate; otherwise, the simulation of the overhead line tree-line contact fault signal is inaccurate; is the set threshold.

[0024] As can be seen from the above, by calculating the correlation between the simulated signal and the measured signal in the contact stage, the water evaporation stage, and the carbonization stage, and calculating the average correlation coefficient based on these correlations, this method can quantitatively evaluate the simulation accuracy of the overhead line tree-line contact fault signal. By setting the threshold , it is possible to objectively judge whether the simulated signal is accurate, thus avoiding the error of subjective judgment, improving the reliability and accuracy of fault simulation, and providing strong support for fault analysis and the formulation of protection strategies.

[0025] As described above, the working principle of a method for simulating an overhead line tree contact fault in the present invention is as follows: 1. Pearson correlation coefficient: The Pearson correlation coefficient is a way to measure the similarity of vectors, and its output range is -1 to 1, where 0 represents no correlation, negative values represent negative correlation, and positive values represent positive correlation; the calculation formula for the Pearson correlation coefficient is: ; In the formula: x is the simulated signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; , are the mean and variance of the simulated signal; , are the mean and variance of the measured signal. Embodiment

[0026] Use PSCAD to build a simulation model of a single-phase tree contact fault on an overhead line of a 10 kV system without branches, as Figure 2 shown; this system consists of a 25 km pure overhead line, a 5 km pure cable line, a 16 km hybrid line, and a 9 km hybrid line. The parameters of the overhead line and the cable are shown in Table 1; use this simulation system to simulate the tree contact fault on the overhead line; the total simulation time is 5.5 s, set an early fault at 0 s, and the fault duration is 5.5 s;

[0027] Simulation analysis According to the law of the physical state evolution of the tree medium, the fault process is divided into four dynamic stages: contact, water evaporation, carbonization, and open fire. Resistivity dynamic correlation models are established respectively: an exponential resistivity model considering temperature correction in the contact stage , a water content attenuation function is adopted in the water evaporation stage , a power-law decay term is introduced in the carbonization stage , in the open fire stage, the fault process oscillation is characterized by a decaying oscillation function , and finally a dynamic impedance evolution equation integrating electro-thermal-humidity multi-field coupling is formed; a piecewise function is used to achieve refined simulation of the full fault cycle.

[0028] The measured signal waveform of the overhead line tree-touching fault I is as Figure 3 shown; by dividing the resistivity into four sections, the contact stage (0.00 - 17.40 s), water evaporation stage (17.40 - 25.57 s), carbonization stage (25.57 - 28.50 s), and open fire stage (28.50 - 52.00 s) during the fault process are respectively characterized; the simulation comparison diagram of the tree-touching fault signal is as Figure 4 shown, and the simulation parameters are shown in Table 2; the Pearson correlation coefficients of the simulated signal and the measured signal in the contact stage (0.00 - 17.40 s), water evaporation stage (17.40 - 25.57 s), carbonization stage (25.57 - 28.50 s), and open fire stage (28.50 - 52.00 s) are shown in Table 3;

[0029] The measured waveform of the overhead line tree-touching fault II is as Figure 5 shown. By dividing the resistivity into four sections, the contact stage (0.00 - 238.50 s), water evaporation stage (238.50 - 388.75 s), carbonization stage (388.75 - 419.00 s), and open fire stage (419.00 - 550.00 s) during the fault process are respectively characterized; the simulation comparison diagram of the tree-touching fault signal of the second measurement is as Figure 6 shown, and the simulation parameters are shown in Table 4; the Pearson correlation coefficients of the simulated signal and the measured signal in the contact stage (0.00 - 238.50 s), water evaporation stage (238.50 - 388.75 s), carbonization stage (388.75 - 419.00 s), and open fire stage (419.00 - 550.00 s) are shown in Table 5.

[0030]

[0031] As can be seen from the above, the present invention realizes high-precision simulation of the full-cycle dynamic characteristics of overhead line tree-touching faults by establishing a segmented resistivity model that integrates the electro-thermal-humidity multi-field coupling effect. The core innovation lies in decoupling the fault evolution process into four physical state evolution stages: contact, moisture evaporation, carbonization, and open fire. Resistivity dynamic models such as temperature-corrected exponential type, water content attenuation function, power-law attenuation term, and attenuation oscillation function are established respectively, and simulation verification is carried out based on the parameter sets in Table 2 and Table 4. The Pearson correlation coefficients of the contact, evaporation, and carbonization stages between the simulated signal and the measured signal waveform 1 reach 0.9911, 0.9849, and 0.9557 (average 0.9882 > 0.97); the Pearson correlation coefficients of the contact, evaporation, and carbonization stages between the simulated signal and the measured signal waveform 2 reach 0.9991, 0.9250, and 0.9996 (average 0.9745 > 0.97), indicating that the model can accurately characterize the electro-thermal-humidity multi-field coupling characteristics.

[0032] To sum up: This method first constructs a series equivalent circuit model composed of arc resistance, contact resistance, and tree body resistance based on the physical characteristics of the current path when the overhead line contacts the tree, so as to quantitatively characterize the fault current path; Subsequently, according to the physical state change law of the tree medium during the tree-touching fault process, the fault process is divided into four stages: contact, moisture evaporation, carbonization, and open fire, and a dynamic correlation model between resistivity and fault state is established to drive the dynamic change of the resistance in each stage; Finally, the Pearson correlation coefficient method is used to compare the correlation between the simulated signal and the measured signal in each stage, and the average correlation coefficient in the contact, moisture evaporation, and carbonization stages is calculated to evaluate the simulation accuracy. When the average correlation coefficient exceeds the set threshold, it is determined that the simulation is accurate; Through full-stage dynamic modeling and refined simulation, this method fully considers the time-varying characteristics of the physical state change of the tree medium, significantly improving the physical authenticity of the simulation and the continuity of stage transition. At the same time, multi-stage correlation verification and reliability criteria are introduced, and the Pearson correlation coefficient method is used to quantify the simulation accuracy, enhancing the credibility and engineering applicability of the fault simulation results. This method provides an effective fault simulation means for the field of relay protection technology of power system distribution networks, helps to improve the sensitivity and accuracy of fault detection, and is of great significance for ensuring the safety of the power grid.

[0033] An overhead line tree-touching fault simulation device, which is applied to the above-mentioned overhead line tree-touching fault simulation method, includes: Circuit model construction module: Based on the physical characteristics of the current path when the overhead line contacts the tree, construct a series equivalent circuit model composed of arc resistance R a , contact resistance R c , and tree body resistance R v ; Fault stage division and resistivity dynamic correlation module: According to the physical state change law of tree media during the development of the tree-touching fault, the fault process is divided into four physical processes: the contact stage, the water evaporation stage, the carbonization stage, and the open fire stage, and a dynamic correlation model between resistivity and fault state is established; Signal simulation and correlation calculation module: Using the outputs of the circuit model construction module and the fault stage division and resistivity dynamic correlation module, simulate the tree-touching fault signal of the overhead line, and calculate the correlation between the simulated signal and the measured signal in each stage respectively using the Pearson correlation coefficient method; Simulation accuracy judgment module: Based on the output of the signal simulation and correlation calculation module, construct a judgment basis. When the average correlation coefficient meets the set threshold it is determined that the simulation of the tree-line contact fault signal of the overhead line is accurate; otherwise, it is determined that the simulation is inaccurate; User interface and data management module: Provide a user interface, allowing users to input parameters, view simulation results, adjust thresholds, etc., and manage data storage and retrieval during the simulation process.

[0034] As can be seen from the above, through the collaborative work of the above modules, the tree-touching fault simulation device of the overhead line can achieve refined simulation of the whole process of the tree-touching fault of the overhead line, and quantitatively evaluate the simulation accuracy, providing an effective fault simulation and analysis tool for the field of relay protection technology of the power system distribution network.

[0035] An embodiment of the present application provides an electronic device, applicable to the above-mentioned tree-touching fault simulation method for an overhead line, including: A memory for protecting computer programs and data; A processor for running system programs.

[0036] An embodiment of the present application provides a computer storage medium, applicable to the above-mentioned tree-touching fault simulation method for an overhead line, and performs hierarchical confidentiality management on the above system and data according to the requirements of confidentiality management.

[0037] Those skilled in the art should understand that the embodiments of the present application can be provided as a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0038] This application is described with reference to the flowcharts and / or block diagrams of devices (systems) and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combinations of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices generate means for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0039] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufacture including instruction means that implement the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0040] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 or means for implementing the functions specified in multiple blocks.

[0041] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0042] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory, such as read-only memory (ROM) or flash memory (flash RAM). The memory is an example of computer-readable media.

[0043] Computer readable media include permanent and non-permanent, removable and non-removable media, and can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0044] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, commodity or device including the elements.

[0045] The embodiments of the present invention are provided for the purpose of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for simulating the fault of overhead lines contacting trees, characterized in that: Comprising the following steps: Step 1: Based on the physical characteristics of the current path when the overhead line contacts the tree, establish a series equivalent circuit model composed of the arc resistance R a , the contact resistance R c , and the tree body resistance R v ; Step 2: According to the physical state change law of tree medium during the development of tree-touching fault, it is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open fire stage; establish a dynamic correlation model between resistivity and fault state, denoted as , , , , drive the dynamic changes of arc resistance R a , contact resistance R c , tree body resistance R v . Step 3: Calculate the correlation between the contact stage, water evaporation stage, carbonization stage, and open fire stage of the simulated signal and the corresponding contact stage, water evaporation stage, carbonization stage, and open fire stage of the measured signal respectively using the Pearson correlation coefficient method, denoted as ; water evaporation stage ; carbonization stage ; open fire stage and the corresponding contact stage ; water evaporation stage ; carbonization stage ; open fire stage of the measured signal, denoted as ; Calculate the average correlation coefficients for the contact stage, the moisture evaporation stage, and the carbonization stage ; Step 4: Based on the average correlation coefficient in Step 3 Construct a criterion.

2. The method for simulating the fault of overhead line contacting a tree according to claim 1, characterized in that: The arc resistance in step 1 R a , the contact resistance R c and the tree body resistance R v are as follows: Arc resistance R a It is calculated as follows: ； Wherein, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median value at which the arc voltage changes from the power supply voltage to 0, i f is the fault current flowing through the trunk at any time, and its formula is as follows: ； In the formula, u b is the voltage on the hemispherical surface of the boundary of the breakdown region with a radius of ; Its formula Comprising: ； Wherein, is the voltage on the tree, is the critical breakdown field strength of the medium; Contact resistance R c It is calculated as follows: ； In the formula, is the resistivity of the tree trunk, is the radius of the breakdown region, is a higher-order infinitesimal of Tree body resistance R v The calculation is as follows: ； In the formula, S is the cross-sectional area of the tree trunk, ρ is the resistivity of the tree trunk, h is the height of the tree trunk.

3. The method for simulating the fault of overhead line contacting a tree according to claim 1, wherein: In step 2, the segmentation is as follows: During The time period is the contact stage, and the tree trunk resistivity formula is as follows: ； Wherein, ρ 0 is the resistivity of the medium at the ambient temperature, T 0 is the ambient temperature, T is the trunk temperature, k m is the resistivity correction factor, k A is a constant related to the material; During the time period is the water evaporation stage, and the formula for the trunk resistivity is as follows: ； Wherein, ρ 10 is the final value of the resistivity at the contact stage, k n is the resistivity correction coefficient, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of the water content of the tree trunk; The water content of the tree trunk is: ； In the formula, k e is the moisture content amplitude coefficient; During the time period is the carbonization stage, and the formula for the resistivity of the tree trunk is as follows: ； In the formula, ρ 20 are respectively the final values of the resistivity in the moisture evaporation stage, is the carbonation control coefficient, t 30 is the initial moment in the carbonation stage; During the time period is the open flame stage, and the resistivity formula is as follows: ； In the formula, is the attenuation DC component control coefficient, k r1 is the amplitude coefficient of the attenuation DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle; The formula for the resistivity of the tree-touching fault is as follows: ； Wherein, is the resistivity at the contact stage, is the resistivity at the moisture evaporation stage, is the resistivity at the carbonization stage, is the resistivity at the open fire stage.

4. The simulation method for overhead line tree-touching fault according to claim 1, wherein: In step 3, the calculation formula for the Pearson correlation coefficient is: ； Wherein: x is the analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the analog signal and the measured signal; and are the mean and variance of the analog signal; and are the mean and variance of the measured signal; Average correlation coefficients for the contact stage, water evaporation stage, and carbonization stage The calculation formula is as follows: ； If , the simulation of the overhead line tree-line contact fault signal is accurate; otherwise, the simulation of the overhead line tree-line contact fault signal is inaccurate; is the set threshold value.

5. An overhead line tree-touching fault simulation device, characterized in that, Applied to an overhead line tree-touching fault simulation method according to any one of claims 1-4, comprising: Circuit model construction module: Based on the physical characteristics of the current path when an overhead line comes into contact with a tree, a series equivalent circuit model composed of an arc resistance R a , contact resistance R c , and tree body resistance R v is constructed; Fault stage division and resistivity dynamic correlation module: According to the physical state change law of the tree medium during the development of the tree-touching fault, the fault process is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open fire stage, and a dynamic correlation model between resistivity and fault state is established; Signal simulation and correlation calculation module: Using the output of the circuit model construction module and the fault stage division and resistivity dynamic correlation module, simulate the overhead line tree-touching fault signal, and calculate the correlation between the simulated signal and the measured signal in each stage using the Pearson correlation coefficient method; Analog accuracy judgment module: Based on the output of the signal simulation and correlation calculation module, a judgment basis is constructed. When the average correlation coefficient meets the set threshold , it is determined that the simulation of the overhead line tree-line contact fault signal is accurate; otherwise, it is determined that the simulation is inaccurate; User interface and data management module: Provide a user interface, allowing users to input parameters, view simulation results, adjust thresholds, etc., and manage data storage and retrieval during the simulation process.

6. A processor, characterized in that: Configured to execute an overhead line tree-touching fault simulation method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: Stored thereon is a computer program, and when the computer program is executed by a processor, it implements an overhead line tree-touching fault simulation method according to any one of claims 1 to 4.

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