A method for simulating tree-touching faults in overhead lines

Abstract

The present invention belongs to the technical field of relay protection of power system distribution networks, and provides a method for simulating overhead line tree-touching faults, comprising the following steps: step 1, establishing a circuit model based on the physical characteristics of the current path when the overhead line contacts a tree; step 2, dividing the physical process according to the law of the physical state change of the tree medium during the development of the tree-touching fault, and establishing a dynamic resistivity model of each stage; step 3, respectively calculating the correlation of the simulation signals using the Pearson correlation coefficient method; step 4, constructing a criterion based on the average correlation coefficient #imgabs0# of step 3; the present invention fully considers the time-varying characteristics of the physical state change of the tree medium through full-stage dynamic modeling and refined simulation, significantly improving the physical reality of the simulation and the continuity of the stage transition; at the same time, introducing multi-stage correlation verification and reliability criterion, using the Pearson correlation coefficient method to quantify the simulation accuracy, thereby enhancing the credibility and engineering applicability of the tree-touching fault simulation results.

Description

Technical Field

[0001] The invention belongs to the technical field of relay protection of power system distribution network, in particular to a method for simulating an overhead line tree-touching fault. Background Art

[0002] With the increase in the number of areas where overhead transmission lines intersect with vegetation, line failures due to tree contact occur frequently, which can easily cause accidents such as tripping and forest fires, threatening the safety of the power grid and the ecological environment.

[0003] The existing high-resistance grounding fault model is difficult to effectively characterize the physical process in which the tree impedance dynamically decreases with the extension of contact time, resulting in problems such as insufficient sensitivity and action delay in the detection algorithm based on steady-state characteristics, which has become a technical bottleneck restricting the prevention and control of wildfires and rapid fault isolation in the distribution network.

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

[0005] In order to solve the above technical problems, the present invention provides a method for simulating overhead line tree-touching faults, which solves the problem that traditional tree-touching fault models ignore the dynamic physical evolution of tree media and cannot accurately characterize the time-varying characteristics of the fault current path, resulting in simulation distortion.

[0006] In a first aspect, the present invention provides a method for simulating an overhead line tree fault, comprising the following steps:

[0007] Step 1: Based on the physical characteristics of the current path when the overhead line contacts the tree, establish the arc resistance R a , contact resistance R c , tree body resistance R v The physical model of overhead line tree fault is constructed by the series coupling of the three, and the quantitative characterization of the fault current path is achieved.

[0008] Step 2: According to the physical state change law of the tree medium during the development of the tree-touching fault, it is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage; a dynamic correlation model between resistivity and fault state is established, recorded as , , , , driving arc resistance R a , contact resistance R c , tree body resistanceR v Dynamic changes of the overhead line tree fault can realize the refined simulation of the whole process;

[0009] Step 3: Use the Pearson correlation coefficient method to calculate the contact phase of the simulation signal , water evaporation stage , carbonization stage , open flame stage Contact phase corresponding to the measured signal , water evaporation stage , carbonization stage , open flame stage The correlation between ; Calculate the average correlation coefficient of the contact stage, water evaporation stage and carbonization stage ;

[0010] Step 4: Average correlation coefficient based on step 3 Construction judgment basis: When the average correlation coefficient satisfy When , the overhead line tree line contact fault signal simulation is accurate; otherwise, the overhead line tree line contact fault signal simulation is inaccurate; is the set threshold.

[0011] Preferably, the arc resistance in step 1 R a , contact resistance R c and tree body resistance R v The formula is as follows:

[0012] Arc resistance R a The calculation is as follows:

[0013] ;

[0014] Where, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median when 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:

[0015] ;

[0016] Where, u b The radius is The voltage on the hemispherical surface of the breakdown region boundary; its formula includes:

[0017] ;

[0018] Where, is the voltage on the trees, is the critical breakdown field strength of the medium;

[0019] Contact resistance R c The calculation is as follows:

[0020] ;

[0021] Where, is the trunk resistivity, is the radius of the breakdown area, for Higher-order infinitesimals of

[0022] Tree body resistance R v The calculation is as follows:

[0023] ;

[0024] Where, S is the cross-sectional area of the trunk, ρ is the trunk resistivity, h is the trunk height.

[0025] Preferably, the step 2 is segmented as follows:

[0026] exist The time period is the contact stage, and the formula for the trunk resistivity is as follows:

[0027] ;

[0028] Where, ρ 0 is the resistivity of the medium at 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;

[0029] exist The time period is the water evaporation stage, and the formula for the tree trunk resistivity is as follows:

[0030] ;

[0031] Where, ρ10 is the final value of the resistivity in the contact stage, k n is the resistivity correction factor, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of trunk water content;

[0032] The water content of the trunk is:

[0033] ;

[0034] Where, k e is the moisture content amplitude coefficient;

[0035] exist The time period is the carbonization stage, and the trunk resistivity formula is as follows:

[0036] ;

[0037] Where, ρ 20 are the final values of resistivity during the water evaporation stage, is the carbonization control coefficient, t 30 is the initial moment of carbonization stage;

[0038] exist The time period is the open flame stage, and the resistivity formula is as follows:

[0039] ;

[0040] Where, is the control coefficient of attenuated DC component, k r1 is the amplitude coefficient of the attenuated DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle;

[0041] The resistivity formula for tree fault is as follows:

[0042] ;

[0043] Where, is the resistivity at the contact stage, is the resistivity during the water evaporation stage, is the resistivity in the carbonization stage, is the resistivity in the open flame stage.

[0044] Preferably, the Pearson correlation coefficient calculation formula in step 3 is:

[0045] ;

[0046] Where: x is an analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; 、 is the mean and variance of the simulated signal; 、 is the mean and variance of the measured signal;

[0047] Average correlation coefficients of contact stage, water evaporation stage and carbonization stage The calculation formula is:

[0048] ;

[0049] like , then the overhead line tree-line contact fault signal simulation is accurate; otherwise, the overhead line tree-line contact fault signal simulation is inaccurate; is the set threshold.

[0050] In a second aspect, the present invention provides an overhead line tree-touching fault simulation device, which is applied to the above-mentioned overhead line tree-touching fault simulation method, comprising:

[0051] Circuit model building module: Based on the physical characteristics of the current path when the overhead line contacts the tree, a circuit model consisting of arc resistance is constructed. R a , contact resistance R c , tree body resistance R v The series equivalent circuit model constructed;

[0052] Fault stage division and resistivity dynamic correlation module: Based on the physical state change law of the tree medium during the development of the tree contact fault, the fault process is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage. A dynamic correlation model between resistivity and fault state is established;

[0053] Signal simulation and correlation calculation module: This module uses the outputs of the circuit model construction module and the fault stage division and resistivity dynamic correlation module to simulate the overhead line tree fault signal and calculates the correlation between the simulated signal and the measured signal at each stage using the Pearson correlation coefficient method.

[0054] Simulation accuracy judgment module: Based on the output of the signal simulation and correlation calculation modules, a judgment basis is constructed. When the average correlation coefficient meets the set threshold When , 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;

[0055] User interface and data management module: Provides a user interface that allows users to input parameters, view simulation results, adjust thresholds, etc., and manages data storage and retrieval during the simulation process.

[0056] In a third aspect, the present invention provides a processor configured to execute the above-mentioned method for simulating an overhead line tree fault.

[0057] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the above-mentioned method for simulating an overhead line tree fault.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1. Full-stage dynamic modeling and refined simulation: This invention establishes a series coupling model of arc resistance, contact resistance, and tree resistance, and incorporates the four-stage physical state evolution of the tree medium (contact, water evaporation, carbonization, and open flame). This innovative dynamic resistivity correlation model is proposed. This model fully accounts for the time-varying characteristics of physical parameters such as temperature, moisture content, and carbonization degree, achieving a dynamic quantitative characterization of the fault current path. Compared to traditional static models, it can more accurately simulate the entire fault progression from initial contact to open flame, significantly improving the simulation's physical realism and the continuity of stage transitions.

[0060] 2. Multi-stage Correlation Verification and Reliability Criteria: This paper introduces the Pearson correlation coefficient method to calculate the local correlation between the simulated and measured signals in four stages. The average correlation coefficient for the contact, evaporation, and carbonization stages is constructed as a comprehensive criterion. This method not only avoids the one-sidedness of single-stage evaluation but also quantifies simulation accuracy through thresholds, making the verification process repeatable and objective. This criterion effectively identifies stages with significant simulation deviations, provides clear guidance for model optimization, and enhances the credibility and engineering applicability of fault simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a flow chart of a method for simulating an overhead line tree fault according to the present invention;

[0062] Figure 2 Schematic diagram of a simulation model for a single-phase tree-touching fault in a branchless 10kV overhead line system according to an embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram of a tree-touching fault signal of an overhead line tree-touching fault measured in accordance with an embodiment of the present invention;

[0064] Figure 4 A schematic diagram showing a comparison between a simulated signal and a measured signal of a tree-touching fault simulation of an overhead line according to an embodiment of the present invention;

[0065] Figure 5 This is a schematic diagram of a tree-touching fault signal during a second measurement of an overhead line tree-touching fault according to an embodiment of the present invention;

[0066] Figure 6 Schematic diagram comparing the simulated signal and the measured signal of the overhead line tree fault simulation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0067] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0068] The present invention provides a method for simulating an overhead line tree fault. Figure 1 As shown, specifically:

[0069] Step 1: Based on the physical characteristics of the current path when the overhead line contacts the tree, establish the arc resistance R a , contact resistance R c , tree body resistance R v The physical model of overhead line tree fault is constructed by the series coupling of the three, and the quantitative characterization of the fault current path is achieved.

[0070] Step 2: According to the physical state change law of the tree medium during the development of the tree-touching fault, it is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage; a dynamic correlation model between resistivity and fault state is established, recorded as , , , , driving arc resistance R a , contact resistance R c , tree body resistance R v Dynamic changes of the overhead line tree fault can realize the refined simulation of the whole process;

[0071] Step 3: Use the Pearson correlation coefficient method to calculate the contact phase of the simulation signal , water evaporation stage , carbonization stage , open flame stage Contact phase corresponding to the measured signal , water evaporation stage , carbonization stage , open flame stage The correlation between ; Calculate the average correlation coefficient of the contact stage, water evaporation stage and carbonization stage ;

[0072] Step 4: Average correlation coefficient based on step 3 Construction judgment basis: When the average correlation coefficient satisfy When , the overhead line tree line contact fault signal simulation is accurate; otherwise, the overhead line tree line contact fault signal simulation is inaccurate; is the set threshold.

[0073] From the above, we can see that, 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, a refined simulation of the entire process of tree contact fault is achieved, which significantly improves the accuracy and physical reality of the simulation; secondly, the Pearson correlation coefficient method is used to perform multi-stage correlation verification, and a reliability criterion based on the average correlation coefficient is constructed, which makes the evaluation of simulation accuracy more objective and repeatable, provides a clear direction for model optimization, and enhances the credibility and engineering applicability of the fault simulation results.

[0074] Specifically, the arc resistance in step 1 R a , contact resistance R c and tree body resistance R v The formula is as follows:

[0075] Arc resistance R a The calculation is as follows:

[0076] ;

[0077] Where, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median when 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:

[0078] ;

[0079] Where, u b The radius is The voltage on the hemispherical surface of the breakdown region boundary; its formula includes:

[0080] ;

[0081] Where, is the voltage on the trees, is the critical breakdown field strength of the medium;

[0082] Contact resistance R c The calculation is as follows:

[0083] ;

[0084] Where, is the trunk resistivity, is the radius of the breakdown area, for Higher-order infinitesimals of

[0085] Tree body resistance R v The calculation is as follows:

[0086] ;

[0087] Where, S is the cross-sectional area of the trunk, ρ is the trunk resistivity, h is the trunk height.

[0088] As can be seen from the above, the above formula accurately quantifies the arc resistance, contact resistance and tree body resistance, taking into account key parameters such as arc voltage, power supply voltage, breakdown area voltage, tree trunk resistivity, cross-sectional area and height. It provides a solid mathematical foundation for constructing a physical model of overhead line tree contact faults, realizes the quantitative characterization of the fault current path, thereby significantly improving the accuracy and reliability of the simulation, and providing strong support for subsequent fault analysis and the formulation of protection strategies.

[0089] Specifically, the step 2 is segmented as follows:

[0090] exist The time period is the contact stage, and the formula for the trunk resistivity is as follows:

[0091] ;

[0092] Where, ρ 0 is the resistivity of the medium at 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;

[0093] exist The time period is the water evaporation stage, and the formula for the tree trunk resistivity is as follows:

[0094] ;

[0095] Where, ρ 10 is the final value of the resistivity in the contact stage, k n is the resistivity correction factor, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of trunk water content;

[0096] The water content of the trunk is:

[0097] ;

[0098] Where, k e is the moisture content amplitude coefficient;

[0099] exist The time period is the carbonization stage, and the trunk resistivity formula is as follows:

[0100] ;

[0101] Where, ρ 20 are the final values of resistivity during the water evaporation stage, is the carbonization control coefficient, t 30 is the initial moment of carbonization stage;

[0102] exist The time period is the open flame stage, and the resistivity formula is as follows:

[0103] ;

[0104] Where, is the control coefficient of attenuated DC component, k r1 is the amplitude coefficient of the attenuated DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle;

[0105] The resistivity formula for tree fault is as follows:

[0106] ;

[0107] Where, is the resistivity at the contact stage, is the resistivity during the water evaporation stage, is the resistivity in the carbonization stage, is the resistivity in the open flame stage.

[0108] As can be seen from the above, the above formula accurately depicts the dynamic changes of tree trunk resistivity with the progress of the fault by introducing key variables such as temperature, moisture content, carbonization degree and time, and realizes the quantitative description of the resistivity of the entire process of tree contact fault, thereby significantly improving the accuracy and refinement of the simulation, providing a more realistic and reliable physical basis for fault simulation and analysis, and contributing to a deeper understanding of the dynamic evolution characteristics of tree contact faults.

[0109] Specifically, the Pearson correlation coefficient calculation formula in step 3 is:

[0110] ;

[0111] Where: x is an analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; 、 is the mean and variance of the simulated signal; 、 is the mean and variance of the measured signal;

[0112] Average correlation coefficients of contact stage, water evaporation stage and carbonization stage The calculation formula is:

[0113] ;

[0114] like , then the overhead line tree-line contact fault signal simulation is accurate; otherwise, the overhead line tree-line contact fault signal simulation is inaccurate; is the set threshold.

[0115] From the above, we can see that by calculating the correlation between the simulated signal and the measured signal in the contact stage, water evaporation stage and 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. , it can objectively judge whether the simulation signal is accurate, thereby avoiding the error of subjective judgment, improving the reliability and accuracy of fault simulation, and providing strong support for fault analysis and protection strategy formulation.

[0116] From the above, the working principle of the overhead line tree fault simulation method of the present invention is as follows:

[0117] 1. Pearson correlation coefficient: The Pearson correlation coefficient is a way to measure the similarity of vectors. Its output range is -1~1, where 0 represents no correlation, negative values represent negative correlation, and positive values represent positive correlation. The Pearson correlation coefficient calculation formula is:

[0118] ;

[0119] Where: x is an analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; 、 is the mean and variance of the simulated signal; 、 are the mean and variance of the measured signal. Example

[0120] Use PSCAD to build a simulation model of a single-phase tree-touching fault in a 10kV overhead line without branches. Figure 2 The 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 lines and cables are shown in Table 1. The simulation system is used to simulate an overhead line tree fault. The total simulation time is 5.5 seconds. The early fault is set to occur at 0 seconds, and the fault duration is 5.5 seconds.

[0121]

[0122] Simulation analysis

[0123] According to the physical evolution law of the wood medium, the failure process is divided into four dynamic stages: contact, water evaporation, carbonization and open fire. The resistivity dynamic correlation model is established respectively: the exponential resistivity model considering temperature correction in the contact stage , the water content attenuation function is used in the water evaporation stage , the power law attenuation term is introduced in the carbonization stage In the open flame stage, the oscillation change of the fault process is characterized by the attenuated oscillation function. , and finally form a dynamic impedance evolution equation that integrates electric-thermal-humidity multi-field coupling; through piecewise functions, a refined simulation of the entire fault cycle is achieved.

[0124] The measured signal waveform of overhead line tree fault is as follows: Figure 3 As shown in the figure; by dividing the resistivity into four sections, the contact stage (0.00-17.40s), water evaporation stage (17.40-25.57s), carbonization stage (25.57-28.50s), and open flame stage (28.50-52.00s) in the fault process are represented respectively; the simulation comparison diagram of the tree fault signal is simulated, as shown in the figure Figure 4 The simulation parameters are shown in Table 2; the Pearson correlation coefficients between the simulated signal and the measured signal in the contact stage (0.00-17.40s), water evaporation stage (17.40-25.57s), carbonization stage (25.57-28.50s), and open flame stage (28.50-52.00s) are shown in Table 3;

[0125]

[0126] The second measured waveform of the overhead line tree fault is as follows: Figure 5 By dividing the resistivity into four sections, the contact stage (0.00-238.50s), water evaporation stage (238.50-388.75s), carbonization stage (388.75-419.00s), and open flame stage (419.00-550.00s) of the fault process are represented respectively; the simulation comparison diagram of the measured tree fault signal is simulated, as shown in the figure below. Figure 6 The simulation parameters are shown in Table 4; the Pearson correlation coefficients between the simulated signals and the measured signals in the contact stage (0.00-238.50s), water evaporation stage (238.50-388.75s), carbonization stage (388.75-419.00s), and open flame stage (419.00-550.00s) are shown in Table 5.

[0127]

[0128] As can be seen from the above, this invention achieves high-precision simulation of the full-cycle dynamic characteristics of an overhead line contact tree fault by establishing a segmented resistivity model that integrates the effects of electro-thermal-moisture multi-field coupling. The core innovation lies in decoupling the fault evolution process into four physical phases: contact, water evaporation, carbonization, and open flame. Dynamic resistivity models, including temperature-corrected exponential, moisture decay function, power-law decay term, and decay oscillation function, are established, respectively. Simulation validation is performed using the parameter sets in Tables 2 and 4. The Pearson correlation coefficients between the simulated and measured signals for waveform 1 for the contact, evaporation, and carbonization phases are 0.9911, 0.9849, and 0.9557 (average 0.9882 > 0.97). The Pearson correlation coefficients between the simulated and measured signals for waveform 2 for the contact, evaporation, and carbonization phases are 0.9991, 0.9250, and 0.9996 (average 0.9745 > 0.97), demonstrating that the model accurately characterizes the electro-thermal-moisture multi-field coupling characteristics.

[0129] In summary, this method first constructs a series equivalent circuit model consisting of arc resistance, contact resistance, and tree body resistance based on the physical characteristics of the current path when an overhead line contacts a tree, to quantitatively characterize the fault current path. Subsequently, based on the physical state changes of the tree medium during a tree contact fault, the fault process is divided into four stages: contact, water evaporation, carbonization, and open flame. A dynamic correlation model between resistivity and fault state is established to drive the dynamic changes in resistance in each stage. Finally, the Pearson correlation coefficient method is used to compare the correlation between the simulated and measured signals at each stage. The simulation accuracy is evaluated by calculating the average correlation coefficient of the three stages: contact, water evaporation, and carbonization. When the average correlation coefficient exceeds the set threshold, the simulation is considered accurate.

[0130] This method, through full-stage dynamic modeling and refined simulation, fully considers the time-varying characteristics of the physical state of the tree medium, significantly improving the simulation's physical realism and the continuity of stage transitions. Furthermore, by introducing multi-stage correlation verification and reliability criteria and quantifying simulation accuracy using the Pearson correlation coefficient method, the reliability and engineering applicability of the fault simulation results are enhanced. This method provides an effective fault simulation method for the field of relay protection technology in power distribution networks, helping to improve the sensitivity and accuracy of fault detection and is of great significance for ensuring power grid security.

[0131] An overhead line tree-touching fault simulation device, applied to the above-mentioned overhead line tree-touching fault simulation method, comprises:

[0132] Circuit model building module: Based on the physical characteristics of the current path when the overhead line contacts the tree, a circuit model consisting of arc resistance is constructed. R a , contact resistance R c , tree body resistance Rv The series equivalent circuit model constructed;

[0133] Fault stage division and resistivity dynamic correlation module: Based on the physical state change law of the tree medium during the development of the tree contact fault, the fault process is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage. A dynamic correlation model between resistivity and fault state is established;

[0134] Signal simulation and correlation calculation module: This module uses the outputs of the circuit model construction module and the fault stage division and resistivity dynamic correlation module to simulate the overhead line tree fault signal and calculates the correlation between the simulated signal and the measured signal at each stage using the Pearson correlation coefficient method.

[0135] Simulation accuracy judgment module: Based on the output of the signal simulation and correlation calculation modules, a judgment basis is constructed. When the average correlation coefficient meets the set threshold When , 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;

[0136] User interface and data management module: Provides a user interface that allows users to input parameters, view simulation results, adjust thresholds, etc., and manages data storage and retrieval during the simulation process.

[0137] It can be seen from the above that through the collaborative work of the above modules, the overhead line tree contact fault simulation device can realize the refined simulation of the entire process of the overhead line tree contact fault and quantitatively evaluate the simulation accuracy, providing an effective fault simulation and analysis tool for the field of power system distribution network relay protection technology.

[0138] An embodiment of the present application provides an electronic device applicable to the above-mentioned method for simulating an overhead line tree fault, including:

[0139] Memory, used to protect computer programs and data;

[0140] Processor, used to run system programs.

[0141] An embodiment of the present application provides a computer storage medium, which is applicable to the above-mentioned overhead line tree fault simulation method, and performs hierarchical confidentiality management on the above-mentioned system and data in accordance with confidentiality management requirements.

[0142] Those skilled in the art will appreciate that the embodiments of the present application may be provided as a system or a computer program product. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0143] The present application is described with reference to the flowcharts and / or block diagrams of the devices (systems) and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes 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 a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0144] These computer program instructions may 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, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0145] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0146] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0147] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0148] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology for information storage. 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 disc read-only memory (CD-ROM), digital versatile disc (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 transitory computer-readable media such as modulated data signals and carrier waves.

[0149] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, commodity, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, commodity, or apparatus comprising the element.

[0150] 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 an overhead line tree fault, characterized by: The steps include: Step 1: Based on the physical characteristics of the current path when the overhead line contacts the tree, establish the arc resistance R a , contact resistance R c , tree body resistance R v The series equivalent circuit model constructed; Step 2: According to the physical state change law of the tree medium during the development of the tree-touching fault, it is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage; a dynamic correlation model between resistivity and fault state is established, recorded as , driving arc resistance R a , contact resistance R c , tree body resistance R v Dynamic changes; the step 2 is segmented as follows: exist The time period is the contact stage, and the formula for the trunk resistivity is as follows: ； Where, ρ 0 is the resistivity of the medium at 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; exist The time period is the water evaporation stage, and the formula for the tree trunk resistivity is as follows: ； Where, ρ 10 is the final value of the resistivity in the contact stage, k n is the resistivity correction factor, b is the adjustment coefficient, m e is the water content of the tree trunk, m e0 is the initial value of trunk water content; The water content of the trunk is: ； Where, k e is the moisture content amplitude coefficient; exist The time period is the carbonization stage, and the trunk resistivity formula is as follows: ； Where, ρ 20 are the final values of resistivity during the water evaporation stage, is the carbonization control coefficient, t 30 is the initial moment of carbonization stage; exist The time period is the open flame stage, and the resistivity formula is as follows: ； Where, is the control coefficient of attenuated DC component, k r1 is the amplitude coefficient of the attenuated DC component, k r2 is the amplitude coefficient of the oscillation component, is the angular frequency, is the phase angle; The resistivity formula for tree fault is as follows: ； Where, is the resistivity at the contact stage, is the resistivity during the water evaporation stage, is the resistivity in the carbonization stage, is the resistivity during the open flame stage; Step 3: Use the Pearson correlation coefficient method to calculate the contact phase of the simulation signal , water evaporation stage , carbonization stage , open flame stage Contact phase corresponding to the measured signal , water evaporation stage , carbonization stage , open flame stage The correlation between ; Calculate the average correlation coefficient of the contact stage, water evaporation stage and carbonization stage ; Step 4: Average correlation coefficient based on step 3 Construct criteria.

2. The method for simulating an overhead line tree fault according to claim 1, wherein: The arc resistance in step 1 R a , contact resistance R c and tree body resistance R v The formula is as follows: Arc resistance R a The calculation is as follows: ； Where, u a is the arc voltage, u s is the power supply voltage, u ath is the voltage median when 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: ； Where, u b The radius is The voltage on the boundary hemisphere of the breakdown region; Its formula include: ； Where, is the voltage on the trees, is the critical breakdown field strength of the medium; Contact resistance R c The calculation is as follows: ； Where, is the trunk resistivity, is the radius of the breakdown area, for Higher-order infinitesimals of Tree body resistance R v The calculation is as follows: ； Where, S is the cross-sectional area of the trunk, ρ is the trunk resistivity, h is the trunk height.

3. The method for simulating an overhead line tree fault according to claim 1, wherein: The calculation formula of the Pearson correlation coefficient in step 3 is: ； Where: x is an analog signal; y is the measured signal; is the correlation coefficient; is the covariance between the simulated signal and the measured signal; 、 is the mean and variance of the simulated signal; 、 is the mean and variance of the measured signal; Average correlation coefficients of contact stage, water evaporation stage and carbonization stage The calculation formula is: ； like > , then the overhead line tree-line contact fault signal simulation is accurate; otherwise, the overhead line tree-line contact fault signal simulation is inaccurate; is the set threshold.

4. An overhead line tree fault simulation device, characterized in that: A method for simulating an overhead line tree fault as claimed in any one of claims 1 to 3, comprising: Circuit model building module: Based on the physical characteristics of the current path when the overhead line contacts the tree, a circuit model consisting of arc resistance is constructed. R a , contact resistance R c , tree body resistance R v The series equivalent circuit model constructed; Fault stage division and resistivity dynamic correlation module: Based on the physical state change law of the tree medium during the development of the tree contact fault, the fault process is divided into four physical processes: contact stage, water evaporation stage, carbonization stage, and open flame stage. A dynamic correlation model between resistivity and fault state is established; Signal simulation and correlation calculation module: This module uses the outputs of the circuit model construction module and the fault stage division and resistivity dynamic correlation module to simulate the overhead line tree fault signal and calculates the correlation between the simulated signal and the measured signal at each stage using the Pearson correlation coefficient method. Simulation accuracy judgment module: Based on the output of the signal simulation and correlation calculation modules, a judgment basis is constructed. When the average correlation coefficient meets the set threshold When , 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: Provides a user interface that allows users to input parameters, view simulation results, adjust thresholds, etc., and manages data storage and retrieval during the simulation process.

5. A processor, characterized in that: The method is configured to execute an overhead line tree fault simulation method according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, an overhead line tree fault simulation method according to any one of claims 1 to 3 is implemented.

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