A method, system, device and medium for calculating a lightning overvoltage peak value

Abstract

The application discloses a lightning overvoltage peak value calculation method, system, device and medium, comprising: based on the finite difference time domain algorithm, the lightning electromagnetic coupling process under different ground resistivity and lightning distance is simulated, the magnetic field response quantity and the overvoltage peak value response quantity are extracted, and the correction coefficient function and the parameter function related to the ground resistivity are fitted respectively; the lightning current peak value at the time of lightning is obtained through a lightning current acquisition device; the equivalent complex depth under the non-ideal ground condition is calculated in combination with the above functions, and the equivalent complex depth, the lightning current peak value and the line electrical geometric parameters are substituted into the closed-form analytical model to quickly solve the lightning induction overvoltage peak value of the overhead line. The application effectively overcomes the problem of insufficient precision of the traditional model under the scene of high soil resistivity and long distance lightning, and takes into account the calculation efficiency and engineering practicability.

Description

Technical Field

[0001] This invention relates to the field of lightning protection technology for power transmission lines, and in particular to a method, system, equipment, and medium for calculating peak lightning overvoltage. Background Technology

[0002] Insulators on overhead transmission lines have a relatively low critical flashover voltage, making them susceptible to being "broken down" by overvoltages generated by induced lightning or direct lightning strikes during nearby lightning activity, leading to flashover faults. Once a flashover occurs, it not only causes line tripping and power outages but can also damage other electrical equipment, severely impacting the safe and stable operation of the entire power grid. Therefore, rationally designing the insulation coordination system to enhance the flashover resistance of the insulator strings has become a key means of improving the overall reliability of overhead transmission lines. To achieve a scientific insulation coordination design, it is essential to perform highly accurate calculations of the peak value of lightning overvoltages, as this peak value directly determines the appropriateness of the selected insulation level.

[0003] In recent years, the calculation of lightning overvoltage on overhead lines has been a hot topic in power system overvoltage research. Early calculation models often treated the ground as an ideal conductor, assuming infinite conductivity and zero resistivity. However, numerous studies have confirmed that the actual ground has finite conductivity, and its resistivity significantly affects the dissipation process of lightning current on the ground, thus altering the horizontal electric field distribution around the overhead conductor and ultimately affecting the magnitude of lightning overvoltage. This effect is particularly pronounced in areas with high soil resistivity, such as mountainous regions, deserts, or permafrost zones. Since lightning strikes are highly random and unpredictable, and the resulting overvoltage mechanisms involve complex physical processes such as electromagnetic coupling, wave propagation, and grounding system response, existing calculation methods often struggle to accurately reflect the true overvoltage level under high soil resistivity conditions. Therefore, there is an urgent need to establish a method for calculating the peak lightning overvoltage that considers high soil resistivity, filling a gap in the existing analytical framework. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method, system, device, and medium for calculating peak lightning overvoltage to solve the problem that existing technologies do not fully consider the impact of the finite conductivity of the earth on overhead lines, resulting in insufficient accuracy of lightning overvoltage analysis near overhead transmission lines under extreme weather conditions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for calculating the peak value of lightning overvoltage, comprising: The physical model parameters and simulation scenario matrix are set, and the electromagnetic coupling process under different ground resistivity and lightning strike distance is simulated based on the finite difference time-domain algorithm. The magnetic field response corresponding to the mirror effect is extracted from the simulation results, and the correction coefficient function corresponding to the ground resistivity is obtained by fitting. The peak overvoltage response at different lightning strike distances was extracted from the simulation results, and a parameter function corresponding to the earth resistivity was obtained by fitting. A lightning current acquisition device is installed at the grounding end of the overhead line to obtain the peak value of the lightning current when a lightning strike occurs. By combining the correction coefficient function and the parameter function, the equivalent complex depth of the overhead line under non-ideal ground conditions is calculated; Using the equivalent complex depth, the obtained peak lightning current, and the electrical and geometric parameters of the line itself, the peak value of the lightning induced overvoltage of the overhead line is calculated.

[0007] In a preferred embodiment of the lightning overvoltage peak calculation method described in this invention, the correction coefficient function is obtained in the following manner: Based on the finite-difference time-domain algorithm, the transient electromagnetic field distribution in the space surrounding an overhead power line under lightning strike is simulated. Based on the simulation results, the response curve of the magnetic field coupling factor as a function of the earth resistivity is extracted and fitted into a function of the earth resistivity.

[0008] As a preferred embodiment of the lightning overvoltage peak calculation method of the present invention, the parameter function includes a first parameter function, a second parameter function and a third parameter function, which respectively correspond to the amplitude adjustment term, the attenuation index term and the offset compensation term in the analytical expression of lightning induced overvoltage; The first parameter function, the second parameter function, and the third parameter function are all obtained by fitting the nonlinear relationship between the overvoltage peak value and the ground resistivity obtained from simulations using the finite-difference time-domain algorithm at different lightning strike distances.

[0009] As a preferred embodiment of the lightning overvoltage peak calculation method of the present invention, the equivalent complex depth is constructed based on the complex mirror theory considering ground loss. By introducing the correction coefficient function into the influence relationship between soil electromagnetic parameters and mirror depth, the complex mirror depth of the main frequency band of lightning current under high soil resistivity is equivalently characterized, and an engineering complex depth expression related to ground resistivity is obtained. The electrical and geometric parameters of the line itself include the conductor height to ground, conductor wave impedance, electromagnetic wave relative propagation speed along the line, and line terminal open circuit condition. The conductor height to ground, conductor wave impedance, electromagnetic wave relative propagation speed along the line, line terminal open circuit condition, and the equivalent complex depth are substituted into the closed-form analytical formula for induced overvoltage based on the transmission line model to solve for the peak value of lightning induced overvoltage.

[0010] As a preferred embodiment of the lightning overvoltage peak calculation method described in this invention, wherein: the equivalent complex depth Represented as: The correction coefficient function Expressed as: in, The resistivity of the earth. The horizontal distance between the lightning strike point and the overhead power line. , , These are the first parameter function, the second parameter function, and the third parameter function, respectively.

[0011] As a preferred embodiment of the lightning overvoltage peak calculation method described in this invention, wherein: the first parameter function Represented as: The second parameter function Represented as: The third parameter function Represented as: in, , , , This represents the fitting coefficient of the first parameter function. , , This represents the fitting coefficient of the second parameter function. , , , This represents the fitting coefficient of the third parameter function.

[0012] As a preferred embodiment of the lightning overvoltage peak calculation method of the present invention, wherein: the lightning induced overvoltage peak value Calculate using the following formula: in, For line wave impedance, The relative propagation speed of electromagnetic waves, This represents the peak value of the lightning current. The height of the conductor above the ground. For equivalent complex depth, This represents the distance from the lightning strike.

[0013] Secondly, the present invention provides a lightning overvoltage peak calculation system, comprising: The electromagnetic coupling analysis module is used to set physical model parameters and simulation scene matrix. Based on the finite-difference time-domain algorithm, it simulates the electromagnetic coupling process under different earth resistivity and lightning strike distance. It extracts the magnetic field response corresponding to the mirror effect from the simulation results and fits the correction coefficient function corresponding to the earth resistivity. The overvoltage response fitting module is used to extract the peak overvoltage response at different lightning strike distances from the simulation results and fit the parameter function corresponding to the earth resistivity. The lightning current measurement and acquisition module is used to install a lightning current acquisition device at the grounding end of an overhead line to obtain the peak value of the lightning current when a lightning strike occurs. The equivalent complex depth calculation module is used to calculate the equivalent complex depth of overhead lines under non-ideal ground conditions by combining the correction coefficient function and the parameter function. The lightning induced overvoltage peak value calculation module is used to calculate the peak value of the overhead line lightning induced overvoltage by utilizing the equivalent complex depth, the obtained lightning current peak value, and the electrical and geometric parameters of the line itself.

[0014] Thirdly, the present invention provides an electronic device, comprising: Memory, used to store programs; A processor for executing the computer-executable instructions, which, when executed by the processor, implement the steps of the lightning overvoltage peak calculation method.

[0015] Fourthly, the present invention provides a computer-readable storage medium, comprising: when the program is executed by a processor, the step of implementing the lightning overvoltage peak calculation method.

[0016] The beneficial effects of this invention are as follows: This invention constructs a high soil resistivity and long-distance lightning strike scenario matrix based on finite-difference time-domain (FDTD) simulation, extracts the magnetic field coupling factor and overvoltage peak response from it, and fits the correction coefficient function corresponding to the earth resistivity and a three-parameter function containing amplitude, attenuation and offset characteristics to achieve a refined modeling of the electromagnetic coupling process under non-ideal earth conditions. By introducing the correction coefficient function and parameter function to jointly calculate the equivalent complex depth, replacing the traditional ideal mirror assumption, an equivalent characterization of the lightning field attenuation and phase shift effect in high resistivity soil is achieved. By integrating the equivalent complex depth, measured peak lightning current, and line electrical geometric parameters into a closed analytical formula, an engineering application can be realized that the peak value of lightning induced overvoltage of overhead lines can be quickly and accurately calculated without complex electromagnetic simulation, significantly improving the reliability and applicability of lightning protection design in areas with high soil resistivity. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a basic flowchart illustrating a method for calculating peak lightning overvoltage, provided as an embodiment of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0019] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for calculating the peak value of lightning overvoltage is provided, comprising: S100: Set the physical model parameters and simulation scene matrix, simulate the electromagnetic coupling process under different earth resistivity and lightning strike distance based on the finite difference time-domain algorithm, extract the magnetic field response corresponding to the mirror effect from the simulation results, and fit the correction coefficient function corresponding to the earth resistivity. S200: Extract the peak overvoltage response at different lightning strike distances from the simulation results and fit the parameter function corresponding to the earth resistivity. S300: Install a lightning current acquisition device at the grounding end of the overhead line to obtain the peak value of the lightning current when a lightning strike occurs. S400: Combines the correction coefficient function and parameter function to calculate the equivalent complex depth of overhead lines under non-ideal ground conditions; S500: The peak value of lightning induced overvoltage of overhead lines is calculated using the equivalent complex depth, the obtained peak lightning current, and the electrical and geometric parameters of the line itself.

[0020] It should be noted that existing technologies face a series of challenges during operation. These include traditional methods for calculating lightning induced overvoltages, which are mostly based on the assumption of an ideal conductive ground and cannot accurately reflect the significant attenuation and phase shift effects of electromagnetic waves under conditions of high soil resistivity (e.g., 0.25–20 kΩ·m). This results in calculation results that deviate significantly from measured values ​​in typical high-resistivity areas such as mountains and deserts. Classical analytical models (such as the Rusck formula) do not consider the impact of ground loss on the image depth and lack an accurate description of the coupling mechanism when the lightning strike distance is long (e.g., several kilometers or more), making it difficult to adapt to the actual scenarios of wide-area deployment in modern power distribution networks. In addition, existing methods usually rely on fixed empirical coefficients or simplified frequency domain approximations, which have weak generalization ability under the diversity of lightning current waveforms and changes in line parameters. While full-wave electromagnetic simulation has high accuracy, it is computationally time-consuming and cannot meet the needs of rapid engineering evaluation. As a result, there is a dual dilemma of insufficient accuracy and limited practicality in lightning protection design, insulation coordination, and risk assessment.

[0021] Therefore, to address the problem that existing technologies do not fully consider the impact of the finite conductivity of the ground on overhead lines, resulting in insufficient accuracy in analyzing lightning overvoltage near overhead transmission lines under extreme weather conditions, a closed-loop analytical model containing correction coefficient functions and multi-parameter functions was constructed through steps S100-S500 by integrating FDTD simulation data under high soil resistivity with transmission line theory. This model enables high-precision and rapid engineering calculation of the peak value of lightning induced overvoltage of overhead lines under non-ideal ground conditions.

[0022] Example 2, this is an embodiment of the present invention, which provides a method for calculating the peak value of lightning overvoltage based on the previous embodiment, including: In this embodiment of the application, in step S100, physical model parameters (including line height, lightning current waveform, soil electromagnetic properties, etc.) and simulation scene matrix (earth resistivity covering 0.25–2000 Ω·m, lightning strike distance covering 0.25–20 km, and no less than 20 sets of working conditions set in logarithmic or equal intervals) are set.

[0023] In this embodiment of the application, the correction coefficient function in step S100 is obtained in the following way: Based on the finite-difference time-domain algorithm, the transient electromagnetic field distribution in the space surrounding an overhead power line under lightning strike is simulated. Based on the simulation results, the response curve of the magnetic field coupling factor as a function of the earth resistivity is extracted and fitted into a function of the earth resistivity.

[0024] In an optional implementation, the correction coefficient function in step S100 can also be based on the electromagnetic coupling response data obtained under different ground resistivity and lightning strike distance conditions through time-domain finite difference simulation. The data is used to train a neural network model, which can automatically output the corresponding correction coefficient according to the input ground resistivity and lightning strike distance, thereby replacing the original parameterized function expression and being used for subsequent calculation of equivalent complex depth.

[0025] In an optional implementation, the correction coefficient function in step S100 can also pre-calculate the corresponding correction coefficient values ​​based on time-domain finite-difference simulation under multiple discrete working conditions of earth resistivity and lightning strike distance, construct a two-dimensional interpolation table, and in practical applications, query and obtain the required correction coefficients according to the given earth resistivity and lightning strike distance through piecewise linear or spline interpolation.

[0026] In this embodiment of the application, the correction coefficient function in step S100 Expressed as: in, The resistivity of the earth. The horizontal distance between the lightning strike point and the overhead power line. , , These are the first parameter function, the second parameter function, and the third parameter function, respectively.

[0027] In this embodiment of the application, the functional form of the parameter function in step S200 is achieved through the following steps: obtaining overvoltage peak response data under different ground resistivity and lightning strike distance based on time-domain finite-difference simulation, and fitting the data to obtain the parameter function based on the ground resistivity. The exponential-power combination function expression of the independent variable is used to characterize the amplitude adjustment term, attenuation exponent term, and offset compensation term in the analytical model of lightning induced overvoltage.

[0028] In an optional implementation, the functional form of the parameter function in step S200 can also be based on the nonlinear relationship between the overvoltage peak value and the ground resistivity obtained from the finite-difference time-domain simulation. Rational functions with polynomials in both the numerator and denominator are used to fit each parameter to more stably characterize its variation characteristics over a wide resistivity range, and are used to construct an analytical expression for lightning induced overvoltage.

[0029] In an optional implementation, the functional form of the parameter function in step S200 can also be based on the correspondence between the overvoltage peak value and the ground resistivity obtained by the finite-difference simulation in the time domain. Orthogonal polynomials (such as Chebyshev or Legendre polynomials) are used to expand and fit each parameter to approximate its nonlinear characteristics with the change of ground resistivity with high accuracy, and it is used to construct the analytical model of lightning induced overvoltage.

[0030] In this embodiment of the application, the parameter function in step S200 includes a first parameter function, a second parameter function, and a third parameter function, which correspond to the amplitude adjustment term, the attenuation index term, and the offset compensation term in the analytical expression of lightning induced overvoltage, respectively. The first, second, and third parameter functions were all obtained by fitting the nonlinear relationship between the overvoltage peak value and the ground resistivity obtained from simulations using the finite-difference time-domain algorithm at different lightning strike distances.

[0031] In this embodiment of the application, the first parameter function in step S200 Represented as: Second parameter function Represented as: Third parameter function Represented as: in, , , , This represents the fitting coefficient of the first parameter function. , , This represents the fitting coefficient of the second parameter function. , , , This represents the fitting coefficients of the third parameter function. The fitting coefficients are pre-calibrated according to the lightning strike type and stored in a coefficient table. One set of coefficients is applicable to the first lightning strike, and the other set is applicable to subsequent lightning strikes. In engineering applications, the corresponding parameters can be retrieved by looking up the table according to the lightning strike sequence.

[0032] It should be noted that, to accurately characterize the nonlinear variation of lightning-induced overvoltage under conditions of high soil resistivity and long-distance lightning strikes, the parameter function is not a single scalar, but rather consists of three independent sub-functions: corresponding to the amplitude adjustment term, attenuation exponent term, and offset compensation term in the analytical expression, respectively. This three-parameter structure can synergistically reflect the comprehensive influence of ground loss on the overvoltage waveform amplitude, attenuation rate, and reference level, thereby significantly improving the fitting accuracy and generalization ability of the closed-loop model over a wide range of operating conditions.

[0033] It should be noted that the parameter function adopts a three-parameter structure, corresponding to the amplitude adjustment term, attenuation exponent term, and offset compensation term in the analytical expression of lightning induced overvoltage, respectively, to synergistically characterize the comprehensive impact of ground loss on the overvoltage waveform; the equivalent complex depth is constructed based on the electromagnetic loss mechanism under high soil resistivity, and dynamically reflects the change of non-ideal ground on the mirror effect through correction coefficients; the velocity-related correction coefficient introduced in the closed-form analytical formula is obtained by regression of FDTD simulation waveform, effectively distinguishing it from the traditional ideal ground model; in addition, the peak lightning current can be obtained through various methods such as direct measurement, remote inversion, or inductive voltage back-calculation, thereby improving the applicability of this method in different engineering scenarios.

[0034] In this embodiment of the application, the lightning current acquisition device in step S300 includes a Rogowski coil or a fiber optic current sensor, which is installed at the grounding down conductor of the overhead line tower to capture the lightning current waveform at the moment of lightning strike in real time and extract its peak value as the lightning current peak input.

[0035] In this embodiment of the application, the equivalent complex depth in step S400 is constructed based on the complex mirror theory considering earth loss. By introducing the correction coefficient function into the influence relationship between soil electromagnetic parameters and mirror depth, the complex mirror depth of the main frequency band of lightning current under high soil resistivity is equivalently characterized, and an engineering complex depth expression related to earth resistivity is obtained. In an optional implementation, the equivalent complex depth in step S400 can also be based on the frequency domain electromagnetic model of the ground with losses, solving the full-wave Green's function or Sommerfeld integral in the main frequency band of the lightning current, extracting the complex depth value corresponding to the mirror effect, and using it as the equivalent complex depth for subsequent calculation of the peak value of lightning induced overvoltage.

[0036] In an alternative implementation, the equivalent complex depth in step S400 can also be calculated based on the classical skin depth using the earth resistivity, and a dimensionless correction factor calibrated by simulation is introduced to adjust it, thereby obtaining an equivalent complex depth suitable for non-ideal earth conditions, which is then used for the subsequent calculation of the peak value of lightning induced overvoltage.

[0037] Equivalent Complex Depth Represented as: .

[0038] In the embodiments of this application, the earth resistivity is in the range of high soil resistivity, and the lightning strike distance is in the typical range of lightning strike distances that have a significant impact on the induced overvoltage of overhead lines.

[0039] In this embodiment, the electrical and geometric parameters of the line itself in step S500 include the conductor height to ground, conductor wave impedance, electromagnetic wave relative propagation speed along the line, and line terminal open-circuit conditions. These parameters, along with the equivalent complex depth, are substituted into the closed-form analytical formula for induced overvoltage based on the transmission line model to solve for the peak value. Among these parameters, the conductor wave impedance... A typical value is 30 Ω, the relative propagation speed of electromagnetic waves The value ranges from 0.33 to 0.5, and the conductor height above the ground is... Distance from lightning strike It can be obtained through on-site surveys or Geographic Information System (GIS).

[0040] Furthermore, traditional analytical models often employ fixed propagation characteristics under the ideal geodetic assumption, which fails to reflect wave process distortion caused by high-resistivity soils. Therefore, this invention introduces a dynamic correction related to the relative propagation speed of electromagnetic waves by performing parameter regression on numerous overvoltage waveforms obtained from finite-difference time-domain simulations. Positive coefficient, this coefficient is based on The form of embedding in the closed formula effectively characterizes the effect of the finite conductivity of the earth on... The influence of transient wave propagation characteristics along the line distinguishes it from the velocity treatment method of classical Rusck and other models.

[0041] In this embodiment of the application, the calculation model for the peak value of lightning induced overvoltage in step S500 is achieved through the following steps: substituting the equivalent complex depth, the measured peak value of lightning current, and parameters such as the wave impedance of the line, the relative propagation velocity, the conductor height, and the lightning strike distance into a closed analytical formula based on transmission line theory, the peak value of lightning induced overvoltage considering the influence of high soil resistivity is directly calculated.

[0042] In an optional implementation, the calculation model for the peak value of lightning induced overvoltage in step S500 can also be based on the electrical and geometric parameters of the overhead line to construct a multi-segment π-type distributed parameter circuit model, incorporate the ground loss in the form of frequency-related grounding impedance, and use the obtained lightning current waveform as the excitation source to solve the induced overvoltage waveform on the line and extract its peak value through time-domain electromagnetic transient simulation.

[0043] In an optional implementation, the calculation model for the peak value of lightning induced overvoltage in step S500 can also be trained based on a large number of input features (including earth resistivity, lightning strike distance, peak lightning current, conductor height, etc.) generated by time-domain finite difference simulation and the corresponding overvoltage peak value labels, so that it can directly predict the peak value of lightning induced overvoltage according to the actual operating parameters.

[0044] In this embodiment of the application, the peak value of the lightning induced overvoltage in step S500 Calculate using the following formula: in, For line wave impedance, The relative propagation speed of electromagnetic waves, This represents the peak value of the lightning current. The height of the conductor above the ground. For equivalent complex depth, This represents the distance to the lightning strike. (Coefficient) Through high soil electrical The overvoltage waveform obtained from FDTD simulation at resistivity (0.25–20 kΩ·m) is obtained by parameter regression to reflect the influence of ground loss on the wave process along the line, which is different from the velocity correction term under the traditional ideal ground assumption.

[0045] Example 3 is an embodiment of the present invention. This embodiment differs from the first embodiment in that it provides a lightning overvoltage peak calculation system.

[0046] It should be noted that the technical solution of the lightning overvoltage peak calculation system is based on the same concept as the technical solution of the lightning overvoltage peak calculation method described above. For details not described in detail in the technical solution of the lightning overvoltage peak calculation system in this embodiment, please refer to the description of the technical solution of the lightning overvoltage peak calculation method described above.

[0047] This embodiment provides a lightning overvoltage peak calculation system, comprising: The electromagnetic coupling analysis module is used to set physical model parameters and simulation scene matrix. Based on the finite-difference time-domain algorithm, it simulates the electromagnetic coupling process under different earth resistivity and lightning strike distance. It extracts the magnetic field response corresponding to the mirror effect from the simulation results and fits the correction coefficient function corresponding to the earth resistivity. The overvoltage response fitting module is used to extract the peak overvoltage response at different lightning strike distances from the simulation results and fit the parameter function corresponding to the earth resistivity. The lightning current measurement and acquisition module is used to install a lightning current acquisition device at the grounding end of an overhead line to obtain the peak value of the lightning current when a lightning strike occurs. The equivalent complex depth calculation module is used to calculate the equivalent complex depth of overhead lines under non-ideal ground conditions by combining the correction coefficient function and the parameter function. The lightning induced overvoltage peak value calculation module is used to calculate the peak value of the overhead line lightning induced overvoltage by utilizing the equivalent complex depth, the obtained lightning current peak value, and the electrical and geometric parameters of the line itself.

[0048] This embodiment also provides an electronic device applicable to a lightning overvoltage peak calculation method, including: The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement a method for calculating peak lightning overvoltage as described in the above embodiments.

[0049] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for calculating peak lightning overvoltage as proposed in the above embodiments.

[0050] The storage medium proposed in this embodiment and the method for calculating peak lightning overvoltage proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0051] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for calculating peak lightning overvoltage, characterized in that, include: The physical model parameters and simulation scenario matrix are set, and the electromagnetic coupling process under different ground resistivity and lightning strike distance is simulated based on the finite difference time-domain algorithm. The magnetic field response corresponding to the mirror effect is extracted from the simulation results, and the correction coefficient function corresponding to the ground resistivity is obtained by fitting. The peak overvoltage response at different lightning strike distances was extracted from the simulation results, and a parameter function corresponding to the earth resistivity was obtained by fitting. A lightning current acquisition device is installed at the grounding end of the overhead line to obtain the peak value of the lightning current when a lightning strike occurs. By combining the correction coefficient function and the parameter function, the equivalent complex depth of the overhead line under non-ideal ground conditions is calculated; Using the equivalent complex depth, the obtained peak lightning current, and the electrical and geometric parameters of the line itself, the peak value of the lightning induced overvoltage of the overhead line is calculated.

2. The method for calculating peak lightning overvoltage as described in claim 1, characterized in that: The correction coefficient function is obtained in the following way: Based on the finite-difference time-domain algorithm, the transient electromagnetic field distribution in the space surrounding an overhead power line under lightning strike is simulated. Based on the simulation results, the response curve of the magnetic field coupling factor as a function of the earth resistivity is extracted and fitted into a function of the earth resistivity.

3. The method for calculating peak lightning overvoltage as described in claim 1 or 2, characterized in that: The parameter function includes a first parameter function, a second parameter function, and a third parameter function, which correspond to the amplitude adjustment term, the attenuation index term, and the offset compensation term in the analytical expression of lightning induced overvoltage, respectively. The first parameter function, the second parameter function, and the third parameter function are all obtained by fitting the nonlinear relationship between the overvoltage peak value and the ground resistivity obtained from simulations using the finite-difference time-domain algorithm at different lightning strike distances.

4. The method for calculating peak lightning overvoltage as described in claim 3, characterized in that: The equivalent complex depth is constructed based on the complex mirror theory that takes into account earth loss. By introducing the correction coefficient function into the influence relationship between soil electromagnetic parameters and mirror depth, the complex mirror depth of the main frequency band of lightning current under high soil resistivity is equivalently characterized, and an engineering complex depth expression related to earth resistivity is obtained. The electrical and geometric parameters of the line itself include the conductor height to ground, conductor wave impedance, electromagnetic wave relative propagation speed along the line, and line terminal open circuit condition. The conductor height to ground, conductor wave impedance, electromagnetic wave relative propagation speed along the line, line terminal open circuit condition, and the equivalent complex depth are substituted into the closed-form analytical formula for induced overvoltage based on the transmission line model to solve for the peak value of lightning induced overvoltage.

5. The method for calculating peak lightning overvoltage as described in claim 4, characterized in that: The equivalent complex depth Represented as: The correction coefficient function Expressed as: in, The resistivity of the earth. The horizontal distance between the lightning strike point and the overhead power line. , , These are the first parameter function, the second parameter function, and the third parameter function, respectively.

6. The method for calculating peak lightning overvoltage as described in claim 5, characterized in that: The first parameter function Represented as: The second parameter function Represented as: The third parameter function Represented as: in, , , , This represents the fitting coefficient of the first parameter function. , , This represents the fitting coefficient of the second parameter function. , , , This represents the fitting coefficient of the third parameter function.

7. The method for calculating peak lightning overvoltage as described in claim 6, characterized in that: The peak value of lightning induced overvoltage Calculate using the following formula: in, For line wave impedance, The relative propagation speed of electromagnetic waves, This represents the peak value of the lightning current. The height of the conductor above the ground. For equivalent complex depth, This represents the distance from the lightning strike.

8. A lightning overvoltage peak calculation system, using the method described in any one of claims 1-7, characterized in that, include: The electromagnetic coupling analysis module is used to set physical model parameters and simulation scene matrix. Based on the finite-difference time-domain algorithm, it simulates the electromagnetic coupling process under different earth resistivity and lightning strike distance. It extracts the magnetic field response corresponding to the mirror effect from the simulation results and fits the correction coefficient function corresponding to the earth resistivity. The overvoltage response fitting module is used to extract the peak overvoltage response at different lightning strike distances from the simulation results and fit the parameter function corresponding to the earth resistivity. The lightning current measurement and acquisition module is used to install a lightning current acquisition device at the grounding end of an overhead line to obtain the peak value of the lightning current when a lightning strike occurs. The equivalent complex depth calculation module is used to calculate the equivalent complex depth of overhead lines under non-ideal ground conditions by combining the correction coefficient function and the parameter function. The lightning induced overvoltage peak value calculation module is used to calculate the peak value of the overhead line lightning induced overvoltage by utilizing the equivalent complex depth, the obtained lightning current peak value, and the electrical and geometric parameters of the line itself.

9. An electronic device, characterized in that, include: Memory, used to store programs; A processor for loading the program to perform the steps of the method as claimed in any one of claims 1-7.

10. A computer-readable storage medium storing a program, characterized in that, When the program is executed by a processor, it implements the steps of the method as described in any one of claims 1-7.

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