System and method for determining model parameters for tower head gap simulation of overhead power transmission lines

Abstract

The application discloses a tower head gap simulation system and a model parameter determination method of an overhead transmission line. The system comprises a simulation tower head test model, a tower head gap equivalent test model, test equipment and power supply equipment. In the tower head gap equivalent test model, a lower rod electrode is vertically fixed at the center of a plate electrode, the length of the lower rod electrode is adjustable within a first length range, an upper rod electrode is hung directly above the lower rod electrode, an air gap is left between the upper rod electrode and the lower rod electrode, the length of the upper rod electrode is adjustable within a second length range, one end of a grounding wire is connected to the plate electrode, and the other end of the grounding wire is connected to a grounding stake. The test equipment is used for providing an air gap breakdown voltage to the simulation tower head test model and the tower head gap equivalent test model and performing relevant measurement. The power supply equipment is used for supplying power to the test equipment. The application solves the technical problems of high difficulty and large workload in building a tower head gap test model of an overhead transmission line in the related art.

Description

Technical Field

[0001] This application relates to the field of high voltage and insulation technology, and more specifically, to a tower head gap simulation system and model parameter determination method for overhead transmission lines. Background Technology

[0002] The design of external insulation for ultra-high voltage and extra-high voltage power transmission and transformation projects is crucial. Failures in the operation of these projects are often related to the design and selection of external insulation. Therefore, how to select the air gap distance is an important issue in determining the external insulation design of power transmission and transformation projects.

[0003] However, due to significant differences between typical gap structures such as rod-rod and rod-plate structures and electrode structures in power transmission and transformation projects, the discharge voltage per unit length and voltage variation characteristics under different voltage waveforms also differ considerably. Therefore, current power transmission and transformation projects cannot use the discharge characteristics of typical gap structures to reflect the actual discharge characteristics of gaps in the project. Furthermore, the analysis of external insulation faults in transmission lines typically involves establishing simulated tower head test models for experimental analysis. However, the construction of such models is usually constrained by on-site test conditions, and the model construction is difficult and labor-intensive.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This application provides a tower head gap simulation system and model parameter determination method for overhead transmission lines, so as to at least solve the technical problems of high difficulty and large workload in building test models for tower head gaps of overhead transmission lines in related technologies.

[0006] According to one aspect of the embodiments of this application, a tower head gap simulation system for overhead transmission lines is provided, comprising: a simulated tower head test model, a tower head gap equivalent test model, test equipment, and power supply equipment. The simulated tower head test model includes at least one of the following: a conductor-tower test model, and a conductor-tower window test model. The tower head gap equivalent test model includes: a plate electrode, an upper rod electrode, a lower rod electrode, and a grounding wire. The lower rod electrode is vertically fixed at the center of the plate electrode, and its length is adjustable within a first length range. The upper rod electrode is suspended directly above the lower rod electrode, with an air gap between them, and its length is adjustable within a second length range. One end of the grounding wire is connected to the plate electrode, and the other end is connected to a grounding stake. The test equipment includes: a voltage generating device and its associated measuring device for providing air gap breakdown voltage to the simulated tower head test model and the tower head gap equivalent test model; and power supply equipment for supplying power to the test equipment.

[0007] Optionally, the test equipment includes at least one of the following: an impulse voltage generator and its measuring equipment, a power frequency voltage generator and its measuring equipment, and a DC voltage generator and its measuring equipment.

[0008] Optionally, the air gap distance between the upper rod electrode and the lower rod electrode can range from [1m to 9m].

[0009] Optionally, the plate electrode is a metal plate with a square structure, and the side length of the plate electrode is not less than twice the air gap distance.

[0010] Optionally, the upper rod electrode is composed of one or more rod electrodes spliced ​​together, and the length of the upper rod electrode is not less than 1.5 times the air gap distance.

[0011] Optionally, the length of the lower electrode does not exceed the length of the upper electrode, and the length adjustment accuracy of the lower electrode does not exceed 0.1 times the air gap distance.

[0012] Optionally, the upper electrode and the lower electrode have the same diameter.

[0013] According to another aspect of the embodiments of this application, a method for determining model parameters is also provided, comprising: obtaining a first discharge voltage corresponding to different lower rod electrode lengths of a tower head gap equivalent test model at multiple target air gap distances, wherein the first discharge voltage is used to reflect the air gap breakdown voltage of the tower head gap equivalent test model; determining a first relationship between the first discharge voltage and the lower rod electrode length at each target air gap distance; obtaining multiple second discharge voltages of a simulated tower head test model at multiple target air gap distances, wherein the second discharge voltage is used to reflect the air gap breakdown voltage of the simulated tower head test model; substituting each second discharge voltage into the first relationship at the target air gap distance corresponding to the second discharge voltage to obtain the target lower rod electrode length corresponding to each target air gap distance; determining a second relationship between the target air gap distance and the target lower rod electrode length, and determining the model parameters in the tower head gap equivalent test model based on the second relationship.

[0014] Optionally, obtaining the first discharge voltage corresponding to different lower rod electrode lengths of the equivalent test model of the tower head gap under multiple target air gap distances includes: obtaining the first discharge voltage corresponding to different lower rod electrode lengths of the equivalent test model of the tower head gap under multiple target air gap distances using a lifting method test; obtaining multiple second discharge voltages of the simulated tower head test model under multiple target air gap distances includes: obtaining multiple second discharge voltages of the simulated tower head test model under multiple target air gap distances using a lifting method test.

[0015] Optionally, determining a first relationship between the first discharge voltage and the length of the lower rod electrode at each target air gap distance includes: using the least squares method to perform curve fitting on multiple lower rod electrode lengths and multiple first discharge voltages to obtain a first relationship at each target air gap distance; determining a second relationship between the target air gap distance and the target lower rod electrode length includes: using the least squares method to perform curve fitting on multiple target air gap distances and multiple target lower rod electrode lengths to obtain a second relationship.

[0016] In the equivalent test model of tower head gap constructed in this embodiment, the lower rod electrode is vertically fixed at the center of the plate electrode, and the length of the lower rod electrode is adjustable within a first length range. The upper rod electrode is suspended directly above the lower rod electrode, and an air gap is left between the upper and lower rod electrodes. The length of the upper rod electrode is adjustable within a second length range. One end of the grounding wire is connected to the plate electrode, and the other end is connected to the grounding stake. The plate electrode and the rod electrode can accurately simulate the tower head gap structure. The air gap distance can be adjusted by adjusting the length of the upper and lower rod electrodes. At the same time, accurate model parameters can be obtained by conducting discharge tests on the simulated tower head test model and the equivalent test model of tower head gap, thereby constructing an equivalent test model that accurately simulates the tower head gap. This solves the technical problem of high difficulty and large workload in constructing test models of tower head gap for overhead transmission lines in related technologies. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of an optional overhead transmission line tower head gap simulation system according to an embodiment of this application;

[0019] Figure 2 This is a schematic diagram of the structure of an optional tower head gap equivalent test model according to an embodiment of this application;

[0020] Figure 3 This is an optional impact test circuit according to an embodiment of this application;

[0021] Figure 4 This is an optional power frequency test circuit according to an embodiment of this application;

[0022] Figure 5 This is a flowchart illustrating an optional model parameter determination method according to an embodiment of this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0024] It should be noted that the terms "first," "second," etc., used in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] Example 1

[0026] Studies have shown that the positive impulse discharge voltage of insulation gap structures used in engineering, such as conductor-tower and conductor-tower window structures, is higher than that of the typical gap structure rod-plate, but lower than that of the typical gap structure rod-rod. Since rod-plate and rod-rod structures, as two typical electrodes—asymmetric and symmetric electric field electrodes, respectively—are universally significant for studying the discharge characteristics of long gaps, the discharge characteristics of any electrode structure, regardless of AC or impulse voltage, fall between the discharge characteristics of these two typical electrodes, provided that the voltage is the same. Currently, however, there is no suitable gap structure that most closely approximates the discharge characteristics of actual engineering gaps.

[0027] In addition, since the analysis of external insulation faults in transmission lines usually requires the establishment of a simulated tower head test model, the construction of the simulated tower head test model is difficult and labor-intensive due to the constraints of the test site conditions.

[0028] Therefore, the problem of unsatisfactory simulation test results for the tower head gap of overhead transmission lines still needs to be solved.

[0029] To address the aforementioned problems, this application first provides a tower head gap simulation system for overhead transmission lines. Figure 1 This is a schematic diagram of the structure of an optional overhead transmission line tower head gap simulation system according to an embodiment of this application, as shown below. Figure 1As shown, the simulation system includes: a simulated tower head test model 11, a tower head gap equivalent test model 12, test equipment 13, and power supply equipment 14. The simulated tower head test model 11 is used to simulate the real tower head during the test, while the tower head gap equivalent test model 12 is used to replace the real tower head to reduce the difficulty of the test and thus reduce the workload.

[0030] Specifically, the simulated tower head test model 11 includes at least one of the following: conductor-tower body test model 111, conductor-tower window test model 112.

[0031] The tower head gap equivalent test model 12 includes: a plate electrode 121, an upper rod electrode 122, a lower rod electrode 123, and a grounding wire 124. The lower rod electrode 123 is vertically fixed at the center of the plate electrode 121, and the length of the lower rod electrode 123 is adjustable within a first length range. The upper rod electrode 122 is suspended directly above the lower rod electrode 123, and an air gap is left between the upper rod electrode 122 and the lower rod electrode 123. The length of the upper rod electrode 122 is adjustable within a second length range. One end of the grounding wire 124 is connected to the plate electrode 121, and the other end is connected to the grounding stake.

[0032] As an optional implementation, a base 125 can typically be added to mount and fix the lower electrode 123, thereby ensuring the stability of the lower electrode 123. Figure 2 A schematic diagram of the actual structure of an optional tower head gap equivalent test model is shown.

[0033] The test equipment 13 includes: a voltage generating device 131 for providing air gap breakdown voltage to the simulated tower head test model and the tower head gap equivalent test model, and its matching measuring device 132.

[0034] Optionally, the test equipment 13 includes at least one of the following: an impulse voltage generator and its measuring device, a power frequency voltage generator and its measuring device, and a DC voltage generator and its measuring device.

[0035] Power supply device 14 is used to supply power to test equipment 13.

[0036] In this embodiment of the application, the discharge characteristics of the real power transmission circuit need to be reflected by the air gap between the upper rod electrode 122 and the lower rod electrode 123 in the tower head gap equivalent test model 12. Therefore, the range d of the air gap distance between the upper rod electrode 122 and the lower rod electrode 123 is preferably [1m, 9m].

[0037] The tower head gap equivalent test model 12 needs to be grounded during the test. Since the surface of the metal plate has good conductivity, it can ensure that the overlapping plate electrodes are at the same potential. Therefore, the plate electrode 121 in the tower head gap equivalent test model 12 is a metal plate with a regular quadrilateral structure, and the side length of the plate electrode 121 is not less than twice the air gap distance. The metal plate is preferably a galvanized iron plate, which has strong oxidation resistance and can enhance the resistance to rust penetration.

[0038] In addition, the upper rod electrode 122 is composed of one or more rod electrodes spliced ​​together. The length l1 of the upper rod electrode 122 is not less than 1.5 times the air gap distance, that is, l1≥1.5d. The length l2 of the lower rod electrode 123 does not exceed the length l1 of the upper rod electrode 122. The length adjustment accuracy Δl of the lower rod electrode 123 does not exceed 0.1 times the air gap distance d, that is, 0m≤Δl≤0.1d. The upper rod electrode 122 and the lower rod electrode 123 are the same. In this embodiment, it is preferably 60mm.

[0039] When conducting an air gap breakdown test, the voltages that can be applied include: impulse voltage, power frequency AC voltage, and DC voltage. Figure 3 An optional impulse test circuit is shown, wherein an impulse voltage generator consisting of a charging power supply, a damping resistor, a discharge sphere gap, a wavefront resistor, a half-peak resistor, and a voltage divider capacitor provides an impulse voltage to the test model, and the waveform is measured by a matching measuring device.

[0040] When the waveform of the impulse voltage is a positive polarity operating impulse wave, the waveform parameter is denoted as T. p / T2, in this embodiment of the application, the preferred parameters of the positive polarity operating shock wave are 250±20% / 2500±60%us; and when the waveform of the impulse voltage is a lightning shock wave, the waveform parameters are denoted as T1 / T2, in this embodiment of the application, the preferred parameters of the lightning shock wave are 1.2±30% / 50±20%us.

[0041] Figure 4 This paper presents an optional power frequency test circuit, in which a power frequency voltage generator, consisting of a voltage regulator, a transformer, a protective resistor, and a voltage divider capacitor, provides power frequency voltage to the test model, and waveform measurement is performed using matching measuring equipment. In this embodiment, the preferred AC frequency is 45-50Hz.

[0042] In the equivalent test model of tower head gap constructed in this embodiment, the lower rod electrode is vertically fixed at the center of the plate electrode, and the length of the lower rod electrode is adjustable within a first length range. The upper rod electrode is suspended directly above the lower rod electrode, and an air gap is left between the upper and lower rod electrodes. The length of the upper rod electrode is adjustable within a second length range. One end of the grounding wire is connected to the plate electrode, and the other end is connected to the grounding stake. The plate electrode and the rod electrode can accurately simulate the tower head gap structure. The air gap distance can be adjusted by adjusting the length of the upper and lower rod electrodes. At the same time, accurate model parameters can be obtained by conducting discharge tests on the simulated tower head test model and the equivalent test model of tower head gap, thereby constructing an equivalent test model that accurately simulates the tower head gap. This solves the technical problem of high difficulty and large workload in constructing test models of tower head gap for overhead transmission lines in related technologies.

[0043] Example 2

[0044] Based on the tower head gap simulation system for overhead transmission lines provided in Example 1, this application also provides a method for determining model parameters of overhead transmission lines. The complete process of this method will be described in detail below.

[0045] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0046] Figure 5 This is a flowchart illustrating an optional model parameter determination method according to an embodiment of this application, as shown below. Figure 5 As shown, the method includes at least steps S501-S505, wherein:

[0047] Step S501: Obtain the first discharge voltage corresponding to different lower rod electrode lengths for the tower head gap equivalent test model under multiple target air gap distances. The first discharge voltage is used to reflect the air gap breakdown voltage of the tower head gap equivalent test model.

[0048] In this embodiment of the application, the preferred range of the air gap distance is [1m, 9m]; the length adjustment accuracy of the lower rod electrode does not exceed 0.1 times the air gap distance.

[0049] In this embodiment of the application, the equivalent test model of the tower head gap includes: a plate electrode, an upper rod electrode, a lower rod electrode, and a grounding wire. The lower rod electrode is vertically fixed at the center of the plate electrode, and the length of the lower rod electrode is adjustable within a first length range. The upper rod electrode is suspended directly above the lower rod electrode, and an air gap is left between the upper rod electrode and the lower rod electrode. The length of the upper rod electrode is adjustable within a second length range. One end of the grounding wire is connected to the plate electrode, and the other end is connected to the grounding stake.

[0050] In addition, the lifting method test can be used to obtain the first discharge voltage corresponding to different lower rod electrode lengths under multiple target air gap distances in the equivalent test model of the tower head gap.

[0051] As an optional implementation, the voltage generating equipment and its matching measuring equipment for providing air gap breakdown voltage for the tower head gap equivalent test model can be provided by the following test equipment: impulse voltage generator and its measuring equipment, power frequency voltage generator and its measuring equipment, and DC voltage generator and its measuring equipment.

[0052] Specifically, the impulse voltage can be provided by an impulse voltage generator, and its parameters can be determined by matching measuring equipment. When the impulse voltage waveform is a positive polarity operating impulse wave, the waveform parameters are denoted as T. p In this embodiment, the preferred parameters for the positive polarity operating shock wave are 250±20% / 2500±60%us; when the waveform of the impulse voltage is a lightning shock wave, the waveform parameters are denoted as T1 / T2, and in this embodiment, the preferred parameters for the lightning shock wave are 1.2±30% / 50±20%us. Alternatively, a power frequency AC voltage can be provided by a power frequency voltage generator, and the parameters of the power frequency AC voltage can be determined by a matching measuring device; in this embodiment, an AC frequency of 45-50Hz is preferred.

[0053] For example, when the target air gap distance d is 1m, 2m, 3m, 4m, 5m, 6m, 7m, 8m, and 9m, the 50% discharge voltage corresponding to different lower rod electrode lengths can be obtained by adjusting the lower rod electrode length, and this voltage can be used as the first discharge voltage.

[0054] Step S502: Determine the first relationship between the first discharge voltage and the length of the lower rod electrode at each target air gap distance.

[0055] Optionally, the least squares method can be used to perform curve fitting on multiple lower electrode lengths and multiple first discharge voltages to obtain the first relationship for each target air gap distance. For example, if the 50% discharge voltage is denoted as U and the lower electrode length is denoted as l2, then the curves U-l2 for target air gap distances d of 1m, 2m, 3m, 4m, 5m, 6m, 7m, 8m, and 9m can be obtained by least squares fitting, and the first relationship f(U,l2) between U and l2 for each target air gap distance can be determined.

[0056] Step S503: Obtain multiple second discharge voltages of the simulated tower head test model at multiple target air gap distances, wherein the second discharge voltage is used to reflect the air gap breakdown voltage of the simulated tower head test model.

[0057] The simulated tower head test model includes at least one of the following: conductor-tower body test model, conductor-tower window test model.

[0058] Optionally, the lifting method test can be used to obtain multiple second discharge voltages of the simulated tower head test model at multiple target air gap distances, wherein the second discharge voltage is preferably 50% discharge voltage.

[0059] For example, the 50% discharge voltage when the target air gap distance d is 1m, 3m, 5m, 7m, and 9m can be obtained as the second discharge voltage. Then, the discharge characteristic curve relationship between the second discharge voltage and the target air gap distance can be obtained through curve fitting, thereby calculating the second discharge voltage corresponding to target air gap distances of 2m, 4m, 6m, and 8m.

[0060] Step S504: Substitute each second discharge voltage into the first relationship under the target air gap distance corresponding to the second discharge voltage to obtain the target lower rod electrode length corresponding to each target air gap distance.

[0061] For example, by substituting the second discharge voltage when the target air gap distance d is 1m, 2m, 3m, 4m, 5m, 6m, 7m, 8m, and 9m into the first relational expression f(U,l2) for the corresponding target air gap distance, the target lower rod electrode length l2 when the target air gap distance d is 1m, 2m, 3m, 4m, 5m, 6m, 7m, 8m, and 9m is obtained.

[0062] Step S505: Determine the second relationship between the target air gap distance and the target lower rod electrode length, and determine the model parameters in the tower head gap equivalent test model based on the second relationship.

[0063] Optionally, the least squares method can be used to perform curve fitting on the air gap distance d of multiple targets and the lower rod electrode length l2 of multiple targets to obtain the second relationship f(d,l2).

[0064] In this embodiment, the first discharge voltage corresponding to different lower rod electrode lengths of the tower head gap equivalent test model is obtained under multiple target air gap distances. The first discharge voltage reflects the air gap breakdown voltage of the tower head gap equivalent test model. A first relationship between the first discharge voltage and the lower rod electrode length is determined for each target air gap distance. Multiple second discharge voltages of the simulated tower head test model under multiple target air gap distances are obtained. The second discharge voltage reflects the air gap breakdown voltage of the simulated tower head test model. Each second discharge voltage is substituted into the first relationship corresponding to the target air gap distance to obtain the target lower rod electrode length corresponding to each second discharge voltage. A second relationship between the second discharge voltage and the target lower rod electrode length is determined, and model parameters in the tower head gap equivalent test model are determined based on the second relationship, thereby obtaining model parameters of the tower head gap model that most closely approximates the discharge characteristics of the actual transmission line.

[0065] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0066] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0067] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between units or modules may be electrical or other forms.

[0068] The units described as separate components may or may not be physically separate. Similarly, the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0069] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0070] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard drive, magnetic disk, or optical disk.

[0071] The above are merely preferred embodiments of this application. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A tower head gap simulation system for overhead transmission lines, characterized in that, include: The test model for simulating the tower head, the equivalent test model for the tower head gap, the test equipment, and the power supply equipment, among which... The simulated tower head test model includes at least one of the following: conductor-tower body test model, conductor-tower window test model; The equivalent test model for the tower head gap includes: a plate electrode, an upper rod electrode, a lower rod electrode, and a grounding wire. The lower rod electrode is vertically fixed at the center of the plate electrode, and its length is adjustable within a first length range. The upper rod electrode is suspended directly above the lower rod electrode, with an air gap between them, and its length is adjustable within a second length range. One end of the grounding wire is connected to the plate electrode, and the other end is connected to a grounding stake. The test equipment includes: a voltage generating device and its supporting measuring device for providing air gap breakdown voltage to the simulated tower head test model and the tower head gap equivalent test model; The power supply equipment is used to supply power to the test equipment.

2. The system according to claim 1, characterized in that, The test equipment includes at least one of the following: an impulse voltage generator and its measuring device, a power frequency voltage generator and its measuring device, and a DC voltage generator and its measuring device.

3. The system according to claim 1, characterized in that, The air gap distance between the upper electrode and the lower electrode ranges from [1m to 9m].

4. The system according to claim 3, characterized in that, The plate electrode is a metal plate with a regular quadrilateral structure, and the side length of the plate electrode is not less than twice the air gap distance.

5. The system according to claim 3, characterized in that, The upper rod electrode is composed of one or more rod electrodes spliced ​​together, and the length of the upper rod electrode is not less than 1.5 times the distance of the air gap.

6. The system according to claim 5, characterized in that, The length of the lower electrode does not exceed the length of the upper electrode, and the length adjustment accuracy of the lower electrode does not exceed 0.1 times the air gap distance.

7. The system according to claim 1, characterized in that, The upper electrode and the lower electrode have the same diameter.

8. A method for determining model parameters, applied to the tower head gap simulation system for overhead transmission lines according to any one of claims 1 to 7, characterized in that, include: The first discharge voltage corresponding to different lower rod electrode lengths of the tower head gap equivalent test model is obtained under multiple target air gap distances. The first discharge voltage is used to reflect the air gap breakdown voltage of the tower head gap equivalent test model. Determine a first relationship between the first discharge voltage and the length of the lower rod electrode for each of the target air gap distances; Multiple second discharge voltages are obtained for the simulated tower head test model at multiple target air gap distances, wherein the second discharge voltages are used to reflect the air gap breakdown voltage of the simulated tower head test model; Substituting each of the second discharge voltages into the first relationship under the target air gap distance corresponding to the second discharge voltage, the target lower rod electrode length corresponding to each target air gap distance is obtained; A second relationship between the target air gap distance and the target lower rod electrode length is determined, and model parameters in the equivalent test model of the tower head gap are determined based on the second relationship.

9. The method according to claim 8, characterized in that, Obtaining the first discharge voltage corresponding to different lower rod electrode lengths of the equivalent test model of the tower head gap under multiple target air gap distances includes: obtaining the first discharge voltage corresponding to different lower rod electrode lengths of the equivalent test model of the tower head gap under multiple target air gap distances using the lifting method test; Obtaining multiple second discharge voltages of the simulated tower head test model at multiple target air gap distances includes: obtaining multiple second discharge voltages of the simulated tower head test model at multiple target air gap distances using a rise-fall method test.

10. The method according to claim 8, characterized in that, Determining the first relationship between the first discharge voltage and the length of the lower rod electrode for each target air gap distance includes: using the least squares method to perform curve fitting on multiple lower rod electrode lengths and multiple first discharge voltages to obtain the first relationship for each target air gap distance; Determining the second relationship between the target air gap distance and the target lower rod electrode length includes: The second relationship is obtained by curve fitting of the air gap distances of the multiple targets and the lengths of the lower rod electrodes of the multiple targets using the least squares method.

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