External multi-gap arrester volt-time characteristic curve estimation method, device and medium

Abstract

The present invention relates to a method, device and medium for estimating the impulse voltage-time characteristic curve of an external multi-gap lightning arrester. The method includes: selecting at least two different standard lightning pulses to conduct lightning strike tests on the external multi-gap lightning arrester test system, and obtaining the initial starting voltage and the corresponding initial lightning strike damage effect value; constructing the voltage-time curve of each standard lightning pulse, and obtaining the damage effect integral function, and combining the initial starting voltage and the initial lightning strike damage effect value to obtain the initial voltage-time curve of the external multi-gap lightning arrester; based on the initial voltage-time curve of the external multi-gap lightning arrester, using a genetic algorithm to optimize the parameters to obtain the voltage-time curve of the external multi-gap lightning arrester. The device and medium are used to implement the above method. Compared with the prior art, the present invention directly estimates the impulse voltage-time characteristic curve of the external multi-gap lightning arrester by using a genetic algorithm, and obtains a characteristic curve that can accurately reflect the lightning strike impact on the distribution network through a simple estimation method.

Description

Technical Field

[0001] The present invention relates to the field of lightning protection for distribution networks in high voltage and insulation technologies, and in particular to a method, device, and medium for estimating the volt-second characteristic curve of an external multi-gap lightning arrester. Background Art

[0002] The power transmission and distribution system delivers electricity from power plants to power demand centers, such as industries and cities, which are usually far from centralized power generation. Power companies must ensure the reliability of power supply, that is, the power supply must be maintained regardless of any unforeseen events or disturbances inside or outside the power grid. In this case, lightning strikes are one of the most difficult disturbances to handle in the distribution network, and the distribution network, especially transformers, is vulnerable to direct and indirect lightning strikes. To solve this problem, different protection schemes have been proposed, mainly including lightning protection devices (SPDs) or lightning arresters, grounding systems, and space shielding device schemes. Regardless of the protection measures adopted, it is necessary to always conduct research on the impact of lightning strikes, and evaluate the effectiveness of the protection scheme through modeling and simulation to verify that the electrical stress applied to the equipment during lightning strike events remains within its support range. For these studies, it is necessary to fully model all components, and the accuracy of the modeling directly affects the reliability of lightning strike research. Existing modeling objects for lightning strike research include line insulators, poles, grounding, transformers, and protection devices, etc. For example, the Chinese invention patent application "CN105184070A" provides a piecewise fitting method for calculating the volt-second characteristic curve based on the voltage integration method. This method uses the voltage integration method as the insulator flashover criterion, and combines numerical analysis methods to piecewise calculate the volt-second characteristic curve of the insulator string under non-standard waveforms, and conducts continuous piecewise fitting and correction. Although it realizes the research on the lightning withstand of the distribution network through insulator flashover, in practical applications, insulator flashover usually occurs in areas with higher electric field strength. Therefore, its volt-second characteristic curve more reflects the breakdown characteristics of the insulator under specific conditions, making it unable to accurately reflect the impact of lightning strikes on the distribution network, and the method provided by the invention patent application "CN105184070A" is relatively cumbersome and requires multiple piecewise fitting and correction of the curve.

[0003] Therefore, providing a volt-second characteristic curve estimation method that can accurately reflect the impact of lightning strikes on the distribution network and is simple is a technical problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a method, device, and medium for estimating the volt-second characteristic curve of an external multi-gap lightning arrester. By integrating and modeling the three-electrode external gap of the lightning-type pulse, and using a genetic algorithm to adjust the parameters of the integral curve, a real and effective curve is constructed, providing strong support for high-precision lightning strike research.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] According to the first aspect of the present invention, a method for estimating the impulse voltage-time characteristic curve of an external multi-gap lightning arrester is provided. The method includes:

[0007] Build an external multi-gap lightning arrester test system, select at least two different standard lightning pulses to conduct lightning strike tests on the external multi-gap lightning arrester test system, and obtain the initial starting voltage and the corresponding initial lightning strike damage effect value;

[0008] Construct the voltage-time curve of each standard lightning pulse, and obtain the damage effect integral function. Combine the initial starting voltage and the initial lightning strike damage effect value to obtain the initial voltage-time curve of the external multi-gap lightning arrester;

[0009] Based on the initial voltage-time curve of the external multi-gap lightning arrester, use the genetic algorithm to optimize the parameters to obtain the voltage-time curve of the external multi-gap lightning arrester.

[0010] As a preferred technical solution, the expression of the voltage-time curve of the standard lightning pulse is:

[0011] ,

[0012] where, represents the voltage peak generated by the standard lightning pulse; both A and B represent constants and are to be solved.

[0013] As a preferred technical solution, the method for solving the unknown constants A and B is:

[0014] Take the derivative of the minimized double-exponential function with respect to time as the objective function, and its expression is:

[0015] ,

[0016] Solve the constants A and B based on the objective function using the simplex search method, and substitute them into the double-exponential wave function to obtain the voltage-time curve of the standard lightning pulse.

[0017] As a preferred technical solution, the expression of the damage effect integral function is:

[0018] ,

[0019] where, represents at the moment of; represents the breakdown time; represents the applied voltage generated by the standard lightning pulse; starting voltage; , represents the parameter to be determined, and k represents a constant.

[0020] As a preferred technical solution, the method for obtaining the voltage-time curve of the initial external multi-gap arrester includes:

[0021] Obtain all standard lightning impulse voltage-time curves based on the standard lightning impulse voltage-time curve and plot them in the same coordinate system;

[0022] Obtain the abscissa value of the intersection point of each standard lightning impulse voltage-time curve and the initial starting voltage, and this abscissa value is the value in the breakdown effect integral function. Combine with the corresponding initial lightning strike breakdown effect value, and use the breakdown effect integral function to obtain the breakdown time of each standard lightning impulse, that is, the value in the breakdown effect integral function;

[0023] Substitute the breakdown time into the standard lightning impulse voltage-time curve to obtain the ordinate value with the abscissa being the value, and obtain the target coordinate point;

[0024] Connect all the target coordinate points to obtain the voltage-time curve of the initial external multi-gap arrester.

[0025] As a preferred technical solution, the method for obtaining the voltage-time curve of the external multi-gap arrester includes:

[0026] Take the curve parameters to be optimized as genes, encode them to generate chromosomes, randomly generate multiple chromosomes and initialize them within the limit conditions. Among them, when , there is exactly one gene in the genetic algorithm chromosome, which is the starting voltage; when , the genes of the genetic algorithm chromosome are the starting voltage and the parameter to be determined, and the starting voltage is the first gene of the chromosome.

[0027] Select at least any two data points in the preset time interval in the voltage-time curve of the initial external multi-gap arrester, and take the difference between the breakdown effect values of the two data points as the fitness function;

[0028] Calculate the fitness value of each chromosome based on the fitness function and perform selection, crossover, and mutation based on the fitness value to generate a new population;

[0029] Determine whether the new population meets the iteration termination condition. If it meets, the current new population is the optimal parameter set of the starting voltage and the parameter to be determined; otherwise, continue the iterative solution.

[0030] As a preferred technical solution, the above-mentioned limiting conditions include coefficient constraints, and its expression is: ,

[0031] and starting voltage constraints, and its expression is: , where represents the breakdown discharge voltage with a breakdown probability of 50%, which is a known value; represents the standard deviation of the normal distribution.

[0032] As a preferred technical solution, the above-mentioned preset time interval is from 1.5 μs to 8 μs.

[0033] According to the second aspect of the present invention, there is provided an electronic device, including a memory and a processor, where a computer program is stored on the memory, and when the processor executes the program, the above-mentioned method is implemented.

[0034] According to the third aspect of the present invention, there is provided a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned method is implemented.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1). By combining the integral method and the genetic algorithm to estimate the impulse voltage-time characteristic curve of a multi-gap lightning arrester, and performing genetic algorithm iterative optimization on the starting voltage and the undetermined parameter α in the damage effect integral function or only on the starting voltage to obtain the optimal solution of the curve parameters. Compared with the prior art that combines the integral method with the piecewise curve fitting method to obtain the impulse voltage-time characteristic curve, it is more convenient, and can find the global optimal solution, improving the reliability and accuracy of the impulse voltage-time characteristic curve.

[0037] 2). The present invention directly estimates the impulse voltage-time characteristic curve of a multi-gap lightning arrester, which can intuitively reflect the impact on the distribution network under lightning strikes, and is of great significance for evaluating the protection performance of the lightning arrester. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is the flowchart of the method of the present invention;

[0039] Figure 2 is the standard lightning impulse voltage-time curve diagram of the present invention;

[0040] Figure 3 is the chromosome schematic diagram of the genetic algorithm of the present invention;

[0041] Figure 4 is the circuit diagram of the three-stage gap lightning arrester system in the embodiment of the present invention;

[0042] Figure 5This is the curve graph of the method verification result of the present invention. Specific implementation manners

[0043] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Unless otherwise defined, the technical terms or scientific terms involved in this application should be of the ordinary meaning understood by those with ordinary skills in the technical field to which this application belongs. The "one", "a", "an", "the" and other similar words involved in this application do not indicate a quantity limit and can represent a single or plural number. The terms "including", "comprising", "having" and any deformation thereof involved in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or modules (units) is not limited to the listed steps or units, but may further include unlisted steps or units, or may further include other steps or units inherent to these processes, methods, products or devices. The "connection", "connection", "coupling" and other similar words involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. The "and / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0045] Embodiment 1

[0046] To solve the lack of an intuitive and accurate method for realizing lightning strike research in the prior art, this embodiment provides a method for estimating the impulse-voltage-time characteristic curve of an external multi-gap lightning arrester. The flow of this method is as Figure 1 shown and specifically includes:

[0047] S1. Build an external multi-gap lightning arrester test system, select at least two different standard lightning pulses (two different standard lightning pulses are selected in this embodiment) to conduct lightning strike tests on the external multi-gap lightning arrester test system, and obtain the initial starting voltage and the corresponding initial lightning strike damage effect value.

[0048] S2. Construct each standard lightning impulse voltage-time curve, obtain the damage effect integral function, and combine the initial starting voltage and the initial lightning strike damage effect value to obtain the initial external multi-gap arrester voltage-time curve.

[0049] S21. Construct the standard lightning impulse voltage-time curve:

[0050] Model the interruption or arc between the terminals caused by the 1.2 / 50µs standard voltage pulse applied to the multi-gap using the double-exponential wave formula. Specifically, the expression of the double-exponential wave formula is:

[0051] ,

[0052] where, represents the peak voltage generated by the standard lightning impulse; both A and B are constants and need to be solved. The method for solving them is:

[0053] S211. Take the derivative of the minimized double-exponential function with respect to time as the objective function, and its expression is:

[0054] ,

[0055] S212. Solve the constants A and B using the simplex search method based on the objective function, and substitute them into the double-exponential wave function to obtain the standard lightning impulse voltage-time curve.

[0056] After solving through the above steps, the standard lightning impulse 1 and standard lightning impulse 2 curves with the solid + dashed line in the middle can be obtained as shown in Figure 2 .

[0057] S22. Obtain the damage effect integral function:

[0058] The discharge process in gas, liquid, and solid insulation depends on the magnitude and duration of the pulsed voltage. Electric utilities must establish acceptable methods to evaluate the impact of non-standard waveform voltage surges on the electrical insulation of equipment. Any method finally adopted should be verified through laboratory tests. The discharge process that leads to insulation breakdown is called the damage effect (DE) of the applied pulse. For the DE assessment of non-standard voltage waveforms of oil-insulated transformers, an integral method is proposed. In the literature, the DE of the voltage pulse of the insulation system is defined as , where e(t) is the externally applied voltage pulse, expressed as a function of time; K1 and K2 are constants depending on the results of the transformer surge test.

[0059] The above formula is based on the fact that the transformer insulation can withstand a given voltage magnitude K1 for a long time without significantly affecting its service life. DE is a function of voltage amplitude and time, and these two factors should not be given the same weight. The constant K2 is introduced to allow some variation in the relative weights of voltage amplitude or time. The constants K1 and K2 of the transformer insulation system can be estimated by standard lightning impulse tests. The definition of such constants gives the integration method a high degree of flexibility; that is, when the values of K1 and K2 are appropriate, the voltage-time curve is very close to the measured values and consistent with the observed data. Under this assumption, the expression of the damage effect integral function is: , in this formula, DE is a constant that depends on the type of insulation system and the applied voltage; represents the applied voltage generated by the standard lightning impulse; U0 The starting voltage, which depends on the type of gap and the applied impulse voltage; represents the moment of; represents the breakdown time; k represents a constant, and in this embodiment, it is assumed that k = 1.

[0060] In addition to the above formula, this embodiment also provides another damage effect integral function, and its expression is: , represents the undetermined coefficient.

[0061] In this embodiment, the above two forms of the damage effect integral function are uniformly set as: , where, , represents the undetermined parameter, k represents a constant, and this formula is derived by the integration method to evaluate DE. Its working principle is associated with the energy required for dielectric breakdown. Therefore, it can be applied to the multi-gap modeling under non-standard pulses.

[0062] S23. Obtain the initial external multi-gap arrester voltage-time curve:

[0063] S231. Obtain all standard lightning impulse voltage-time curves based on the standard lightning impulse voltage-time curve and plot them in the same coordinate system. The effect is as Figure 2 shown.

[0064] S232. Obtain the abscissa value of the intersection point of each standard lightning impulse voltage-time curve and the straight line where the initial starting voltage (known) is located. This abscissa value is the value in the damage effect integral function, that is Figure 2 in and , and combine it with the corresponding initial lightning strike damage effect value (known), that is Figure 2The shaded part in. At this time, since the corresponding standard lightning impulse voltage-time curve is known, the breakdown time of each standard lightning pulse can be obtained by using the damage effect integral function, that is, the value corresponds to Figure 2 in and .

[0065] S233. Substitute the breakdown time into the standard lightning pulse voltage-time curve to obtain the ordinate value with the abscissa being value, and obtain the target coordinate point.

[0066] S234. Connect all the target coordinate points to obtain the initial external multi-gap arrester voltage-time curve, that is, the Figure 2 "U-t curve" in.

[0067] S3. Based on the initial external multi-gap arrester voltage-time curve, use the genetic algorithm for parameter optimization to obtain the external multi-gap arrester voltage-time curve.

[0068] S31. Use the curve parameters to be optimized as genes, encode them to generate chromosomes, randomly generate 50 chromosomes and initialize them within the limit conditions. Specifically, its encoding effect is as Figure 3 shown, where when , the genetic algorithm chromosome gene has and only has one, which is the Figure 3 starting voltage in; when , the genetic algorithm chromosome genes are the starting voltage and the undetermined parameter, and the starting voltage is the first gene of the chromosome.

[0069] Specifically, its limit conditions include: the coefficient constraint, its expression is: , and the starting voltage constraint, its expression is: , where represents the breakdown discharge voltage with a 50% breakdown probability, which is a known value; represents the standard deviation of the normal distribution.

[0070] Among them, the method for determining the starting voltage constraint is obtained by fitting based on the experimental measurement values and their corresponding normal distribution. The results shown in Table 1 are the experimental results of the positive polarity pulses fitted to the normal distribution and follow the procedure established in Section 15 of IEEE4-2013 standard. In this case, corresponds to the standard deviation, and the 95th percentile confidence interval is shown in square brackets. The p-value of the Kolmogorov-Smirnov test is 0.12.

[0071] Table 1 Analysis table of experimental test results of positive pulses

[0072]

[0073] As can be seen from Table 1, the search space of is defined as

[0074] S32. Select at least any two data points in the interval of 1.5 μs to 8 μs in the initial external multi-gap arrester voltage-time curve. In this embodiment, two data points (Upa, tba) and (Upb, tbb) are selected, and the difference between the damage effect values of the two data points is used as the fitness function, that is, .

[0075] S33. Calculate the fitness value of each chromosome based on the fitness function and perform selection, crossover, and mutation based on the fitness value to generate a new population. The mutation rate and selection rate are 0.4 and 0.5 respectively; the tournament method is used to select parents to generate new individuals in the next generation.

[0076] S34. Determine whether the new population meets the iteration termination condition. If it meets, the current new population is the optimal parameter set of the starting voltage and undetermined parameters; otherwise, continue the iterative solution.

[0077] Embodiment 2

[0078] To verify the feasibility of the method proposed in Embodiment 1, in this embodiment, the simulation results are compared with the experimental measurement results. An external multi-gap arrester test system is built, considering the experimental results corresponding to a 0.1 m spacing under positive standard lightning strike pulses. In this embodiment, the U50 and standard deviation used are 94 kV and 3.1 kV respectively. This verification experiment measurement is carried out using a 400 kV, 10 kJ four-stage Marx pulse generator. A digital peak voltmeter is used to measure the impulse voltage through a 400 kV resistor divider, with a response time less than 60 ns and a measurement accuracy within the range of + / −3%. The breakdown time is directly measured by an oscilloscope recorded by a Yokogawa DL1520 digital oscilloscope, with a bandwidth of 150 MHz and a sampling rate of 200 MS / s. The breakdown frequency and standard deviation of the flashover voltage for each voltage level are determined by 10 to 20 applied pulses. The difference in the applied voltage between consecutive intervals does not exceed 3% of the expected 50% interference discharge voltage.

[0079] The data points selected in this embodiment are (117.4 kV, 1.5 μs) and (184.3 kV, 0.76 μs). Based on the above two data points, the volt-second characteristic curve is estimated using the estimation method provided in Embodiment 1. Specifically, the estimation results are shown in Table 2.

[0080] Table 2 Volt-Second Curve Estimation Parameter Result Table

[0081]

[0082] and construct a circuit as shown in Figure 4 to reproduce the voltage-second characteristic curve obtained in Table 2. The inductor is the inductor of the circuit connected to the high-voltage side of the source, and its value is 10 µH; the value of the inductance of the breakdown gap channel is 1 µH / m. Figure 4 The control module in Figure 5 is a switch that allows controlling the simulated dielectric breakdown. The reproduction results are shown in Figure 5. It can be seen that the U-t curves reproduced by the two curves are very close to the characteristic curves measured experimentally. The average difference between the experimental value and the calculated value of Curve 1 is 0.051 µs, and the average difference of Curve 2 is 0.049 µs, both of which are smaller than the average difference in the prior art. It can be seen from

[0083] In summary, the method proposed in Embodiment 1 is reliable and has a smaller error compared with the results obtained by the methods of the prior art.

[0084] Embodiment 3

[0085] In order to verify the method provided in Embodiment 1, a test experiment was carried out in this embodiment, and first, a positive-polarity pulse (instead of the standard lightning impulse) used for the test experiment was modeled. For each polarity and voltage level, 15 tests were carried out, and it was found that the difference in the basic insulation level (BIL) of the three-electrode gap under the two polarities was less than 4%, as shown in Table 3.

[0086] Table 3 Summary of Measurement Results of Three-Electrode Gap under Standard Positive-Polarity Pulse

[0087]

[0088] It can be seen that the basic insulation level (BIL) of the device does not depend on the polarity of the applied pulse. Therefore, in this study, only positive-polarity pulses were considered. Based on the data in Table 3, a standard positive-polarity pulse voltage-time curve was constructed, and two data points were selected. In this embodiment, the data points corresponding to Level 4 and Level 7 were selected because their relative frequencies allow assuming that the random behavior of the dielectric breakdown process can be ignored, that is, (56.3 kV, 4.236 µs) and (61.2 kV, 2.630 µs). Using the method provided in Embodiment 1 for parameter estimation, the data shown in Table 4 can be obtained.

[0089] Table 4 Results Table of Estimated Parameters of Voltage-Second Curve

[0090]

[0091] As can be seen from Table 4, the starting voltage values obtained from the two curves are detailed, with a difference of 4.311%. In addition, in both cases, the value of the objective function is less than , which can prove that the volt-second characteristic curve estimated by the method provided in Example 1 can more accurately reproduce the actual situation.

[0092] Example 4

[0093] The electronic device of the present invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or computer program instructions loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM, and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0094] Multiple components in the device are connected to the I / O interface, including: an input unit, such as a keyboard, a mouse, etc.; an output unit, such as various types of displays, speakers, etc.; a storage unit, such as a magnetic disk, an optical disc, etc.; and a communication unit, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0095] The processing unit executes the various methods and processes described above, such as methods S1 to S3. For example, in some embodiments, methods S1 to S3 can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program can be loaded and / or installed onto the device via the ROM and / or the communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of methods S1 to S3 described above can be executed. Alternatively, in other embodiments, the CPU can be configured to execute methods S1 to S3 by any other suitable means (e.g., by means of firmware).

[0096] The functions described above herein can be performed at least in part by one or more hardware logic components. For example, by way of non-limitation, exemplary types of hardware logic components that can be used include: field programmable gate arrays (FPGA), application specific integrated circuits (ASIC), application specific standard products (ASSP), system on a chip (SOC), complex programmable logic devices (CPLD), and so on.

[0097] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing devices, such that when the program codes are executed by the processor or controller, the functions / operations specified in the flowchart and / or block diagram are implemented. The program codes can be executed entirely on the machine, partially on the machine, executed partially on the machine and partially on a remote machine as an independent software package, or executed entirely on a remote machine or server.

[0098] In the context of the present invention, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0099] As described above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for estimating the volt-second characteristic curve of an external multi-gap arrester, characterized in that: The method includes: Building an external multi-gap lightning arrester test system, selecting at least two different standard lightning pulses to perform a lightning strike test on the external multi-gap lightning arrester test system, and obtaining an initial starting voltage and a corresponding initial lightning strike damage effect value; Constructing each of the standard lightning pulse voltage-time curves, and obtaining a damage effect integral function, and combining the initial starting voltage and the initial lightning damage effect value to obtain an initial external multi-gap arrester voltage-time curve; Based on the initial external multi-gap arrester voltage-time curve, a genetic algorithm is used to perform parameter optimization to obtain the external multi-gap arrester voltage-time curve.

2. A method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 1, characterized in that: The expression of the standard lightning pulse voltage-time curve is: ， in, represents the peak voltage generated by the standard lightning pulse; A and B are both constants to be solved.

3. A method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 2, characterized in that: The method to solve the unknown constants A and B is: The objective function is to minimize the derivative of the double exponential function with respect to time, and its expression is: ， Based on the objective function, the constants A and B are solved by the simplex search method, and the double exponential wave function is substituted to obtain the standard lightning pulse voltage-time curve.

4. The method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 1, characterized in that: The damage effect integral function expression is: ， in, express moment; Indicates the breakdown time; Indicates the applied voltage due to a standard lightning pulse; Starting voltage; , represents an undetermined parameter, and k represents a constant.

5. A method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 4, characterized in that: The method for obtaining the initial external multi-gap arrester voltage-time curve comprises: Based on the standard lightning pulse voltage-time curve, all standard lightning pulse voltage-time curves are obtained and plotted in the same coordinate system; Obtain the abscissa value of the intersection point of each standard lightning pulse voltage-time curve and the initial starting voltage, which is the abscissa value in the damage effect integral function. The value is combined with the corresponding initial lightning damage effect value, and the breakdown time of each standard lightning pulse is obtained by using the damage effect integral function, that is, value; Substitute the breakdown time into the standard lightning pulse voltage-time curve to obtain the horizontal coordinate: The vertical coordinate value of the value is used to obtain the target coordinate point; Connect all target coordinate points to obtain the initial external multi-gap arrester voltage-time curve.

6. The method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 1, characterized in that: The method for obtaining the voltage-time curve of the external multi-gap arrester includes: The curve parameters to be optimized are used as genes to encode chromosomes, and multiple chromosomes are randomly generated and initialized within the constraints. When , the genetic algorithm chromosome gene has only one, which is the starting voltage; when When , the genetic algorithm chromosome gene is the starting voltage and the parameters to be determined, and the starting voltage is the first gene of the chromosome; Select at least two data points in the initial external multi-gap arrester voltage-time curve located in a preset time interval, and use the difference between the damage effect values ​​of the two data points as the fitness function; Calculating the fitness value of each chromosome based on the fitness function and performing selection, crossover and mutation based on the fitness value to generate a new population; Determine whether the new population meets the iteration termination condition. If so, the current new population is the optimal parameter set of the starting voltage and the parameters to be determined; otherwise, continue to iterate and solve.

7. A method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 6, characterized in that: The restriction conditions include coefficient constraints, which are expressed as follows: , And the starting voltage constraint, its expression is: ,in, The destructive discharge voltage indicating a 50% breakdown probability is a known value; express The standard deviation of the normal distribution.

8. A method for estimating the volt-second characteristic curve of an external multi-gap arrester according to claim 6, characterized in that: The preset time interval is 1.5µs to 8µs.

9. An electronic device for estimating the volt-second characteristic curve of an external multi-gap lightning arrester, comprising a memory and a processor, wherein a computer program is stored in the memory, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

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