A failure evaluation method for a grounding device of a tower in a seasonal frozen soil area

Abstract

The application discloses a failure evaluation method for a grounding device of a tower in a seasonal frozen soil area, relates to the technical field of lightning protection of a power transmission line, and comprises the following steps: a temperature change curve is established, and on the basis of the temperature change curve, the corresponding partition resistivity of different partition soils is obtained; a current dispersion failure model corresponding to a grounding device on a target tower is established, and on the basis of the corresponding partition resistivity of different partition soils and the current dispersion failure model, a failure curve corresponding to the grounding device on the target tower can be obtained; and finally, on the basis of the failure curve corresponding to the target tower, the failure state of the grounding device of the tower in the seasonal frozen soil area can be evaluated, the running state of the grounding device can be better judged, and then measures can be taken according to the running state of the grounding device, so that the harm caused by lightning current is reduced, and the method has great engineering value.

Description

Technical Field

[0001] This invention relates to the field of lightning protection technology for power transmission lines, specifically to a failure assessment method for grounding devices of power poles in seasonally frozen soil areas. Background Technology

[0002] In recent years, with the launch of the large-scale development strategy for green energy in plateau regions, energy transmission projects inevitably pass through high-altitude permafrost areas. Simultaneously, the unique lightning activity in plateau regions presents transmission lines with the severe challenge of coexisting permafrost and lightning strikes. Plateau regions experience numerous thunderstorms annually, with a wide distribution throughout the year. Even in spring and winter, the average monthly number of thunderstorm days can exceed 10. Positive lightning strikes account for over 10%, and their return stroke amplitude is significantly greater than that of negative strikes, averaging up to 97 kA. In such conditions, a lightning strike could cause serious damage. The soil structure in permafrost regions is dynamic and changes with temperature. Some scholars have studied the lightning protection of transmission lines in permafrost areas, investigating lightning activity along the routes. They suggest that in permafrost regions, grounding devices should be buried in the summer thawed soil to calculate the line's lightning resistance level. Other scholars have pointed out that in permafrost regions, soil temperatures can plummet below 0°C at night in summer, potentially causing localized freezing of grounding devices. In such cases, a lightning strike to a tower could result in a backflashover of the insulator strings.

[0003] The metal tower feet of transmission lines are fixed in permafrost. Due to the high thermal conductivity of the tower feet, they act as an internal heat source, changing the local thermal state of the tower base and thus affecting the current dissipation characteristics of the grounding device.

[0004] In the design of grounding devices in seasonally frozen soil areas, the thermal conductivity of the grounding device has usually been ignored in previous engineering projects. The current dissipation performance is ensured by burying the grounding device deep. However, this method does not take into account the thermal conductivity of the grounding device itself. Therefore, this invention proposes a grounding device failure assessment method. This method can better determine whether the current dissipation performance of the grounding device has failed, which is of great significance for the maintenance and assessment of towers in seasonally frozen soil areas. Summary of the Invention

[0005] The purpose of this invention is to provide a failure assessment method for grounding devices of poles in seasonally frozen soil areas, which solves the problem that existing technologies are unable to accurately assess the failure of grounding devices.

[0006] This invention is achieved through the following technical solution:

[0007] A method for assessing the failure of grounding devices on power poles in seasonally frozen soil areas includes:

[0008] Obtain frozen soil test data at the location of the target tower in a seasonally frozen soil region, and establish a temperature change curve based on the frozen soil test data;

[0009] Based on the temperature change curve, the soil is divided into zones using a multi-zone strategy to obtain the corresponding zone resistivity of the soil in different zones.

[0010] A current-spreading failure model corresponding to the grounding device on the target tower is established, and based on the corresponding zone resistivity of soil in different zones and the current-spreading failure model, the failure curve corresponding to the grounding device on the target tower is obtained.

[0011] Based on the failure curve corresponding to the target tower, a failure assessment is conducted on the grounding device on the target tower in the seasonally frozen soil area, and the failure assessment results are obtained.

[0012] In one possible implementation, frozen soil test data is obtained at the location of the target tower in a seasonally frozen soil region, and a temperature change curve is established based on the frozen soil test data, including:

[0013] Obtain frozen soil test data at the location of the target tower in a seasonally frozen soil region. The frozen soil test data includes different temperatures and the resistivity of the frozen soil at different temperatures.

[0014] Based on the resistivity of frozen soil at different temperatures and the resistivity corresponding to different temperatures, a curve of resistivity changing with temperature is constructed to obtain the temperature change curve.

[0015] In one possible implementation, based on the temperature change curve, the soil is divided into zones using a multi-zone strategy to obtain the corresponding zone resistivity of the soil in different zones, including:

[0016] Based on the temperature change curve, a first partition line and a second partition line are determined. The first partition line is used to separate frozen soil from thawed soil. The second partition line is used to separate the resistivity rising trend when the temperature continues to drop. That is, when the increase in resistivity between two consecutive data points is less than a preset threshold, the previous data point can be used as the second partition line.

[0017] Based on the preset first interval length and the first partition line, the first soil partition is determined;

[0018] The second soil zoning is determined based on the first and second zoning lines;

[0019] Based on the preset second interval length and second zoning line, the third soil zoning is determined;

[0020] For the first soil zone, the second soil zone, the third soil zone, and the temperature change curve, the resistivity of each soil zone was determined by the geometric mean method, thereby obtaining the corresponding zone resistivity of the soil in different zones.

[0021] In one possible implementation, a current-spreading failure model corresponding to the grounding device on the target tower is established, and based on the corresponding regional resistivity of soil in different zones and the current-spreading failure model, the failure curve corresponding to the grounding device on the target tower is obtained, including:

[0022] By combining the heat transfer equations of the grounding conductor on the grounding device, the heat transfer equation of the soil, and Darcy's law, and incorporating Dirichlet boundary conditions, a hydrothermal field coupling model considering heat transfer of the grounding conductor was established.

[0023] The spatiotemporal distribution of soil internal temperature was determined using this hydrothermal field coupling model, and the soil structure under different freezing times was obtained.

[0024] Based on the soil structure under different freezing times and the grounding device on the target tower, a current-spreading failure model is constructed; the current-spreading failure model is used as a simulation model to characterize the grounding device and the environment in which the grounding device is located.

[0025] Multiple evenly distributed potential probes are arranged on the grounding device, and a positive current is injected into the top surface of the grounding device. The transient potential peak value is obtained through the potential probes.

[0026] Based on the transient potential peak value, the resistance change curve of the impulse grounding resistance of the grounding device with respect to time is obtained, and the resistance change curve of the grounding device on the target tower is obtained.

[0027] Based on the corresponding resistivity of soil in different zones, the impulse grounding resistance at the time of failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance at the time of failure.

[0028] In one possible implementation, multiple uniformly distributed potential probes are arranged on the grounding device, a positive current is injected into the top surface of the grounding device, and transient potential peaks are obtained through the potential probes, including:

[0029] Multiple evenly distributed potential probes are arranged on the grounding device;

[0030] Injecting a positive current onto the top surface of the grounding device is as follows:

[0031]

[0032]

[0033] Where I(t) represents the positive current, kA; I p η represents the peak current (kA); η represents the peak correction factor; t represents time (μs); τ1 represents the wavefront time (μs); τ2 represents the wave tail time (μs); n represents the integral coefficient.

[0034] The voltage is detected by multiple uniformly distributed potential probes, and the maximum voltage value detected is taken as the transient potential peak value.

[0035] In one possible implementation, based on the transient potential peak value, the resistance change curve of the grounding device's impulse grounding resistance with respect to time is obtained, resulting in the resistance change curve corresponding to the grounding device on the target tower, including:

[0036] Based on the transient potential peak value, the impulse grounding resistance of the grounding device is obtained as follows:

[0037]

[0038] Among them, R ch Indicates impulse grounding resistance, in Ω; V p This represents the peak value of the transient potential, in kV.

[0039] Using time t as a variable, the resistance change curve of the impulse grounding resistance of the grounding device with respect to time is obtained, thus obtaining the resistance change curve of the grounding device on the target tower.

[0040] In one possible implementation, based on the corresponding resistivity of soil in different zones, the impulse grounding resistance at the time of failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance at the time of failure, including:

[0041] Based on the impulse grounding resistance of the grounding device, the corresponding average resistivity is obtained;

[0042] Based on the corresponding resistivity of the soil in different zones, determine whether the average resistivity meets the failure condition. If so, determine that the impulse grounding resistance corresponding to the average resistivity is the impulse grounding resistance corresponding to the failure condition; otherwise, determine that it has not failed.

[0043] Iterate through the impulse grounding resistance corresponding to each time point to obtain the impulse grounding resistance corresponding to all failures.

[0044] Based on the impulse grounding resistance corresponding to the failure point, the failure point is marked on the resistance change curve to obtain the failure curve.

[0045] In one possible implementation, the corresponding average resistivity is obtained based on the impulse grounding resistance of the grounding device:

[0046]

[0047] in, The average resistivity is expressed in Ω*m; l represents the length of the vertical grounding electrode of the grounding device in m; and d represents the radius of the vertical grounding electrode in m.

[0048] In one possible implementation, determining whether the average resistivity meets the failure condition based on the corresponding zone resistivity of the soil in different zones includes:

[0049] Based on the corresponding resistivity of the soil in different zones, the failure impact factor is obtained as follows:

[0050]

[0051] Where α represents the failure impact factor; ρ2 represents the resistivity of the second soil zone, in Ω*m; and ρ3 represents the resistivity of the third soil zone, in Ω*m.

[0052] Determine whether the failure impact factor is greater than a preset threshold. If so, the failure condition is met; otherwise, the failure condition is not met.

[0053] In one possible implementation, it also includes:

[0054] judge If the condition is met, the grounding device is deemed to be obsolete and an alarm message is generated; otherwise, the failure assessment continues.

[0055] This invention provides a failure assessment method for grounding devices on poles in seasonally frozen soil areas. It establishes a temperature change curve and, based on this curve, obtains the corresponding resistivity of soil in different zones. Then, it establishes a current-spreading failure model for the grounding device on the target pole and, based on the corresponding resistivity of soil in different zones and the current-spreading failure model, obtains the failure curve for the grounding device on the target pole. Finally, based on the failure curve of the target pole, the failure state of the grounding device on poles in seasonally frozen soil areas can be assessed. This method can effectively determine the operating status of the grounding device and allow for measures to be taken to reduce the damage caused by lightning current, thus possessing significant engineering value. Attached Figure Description

[0056] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 A flowchart illustrating a failure assessment method for a tower grounding device in a seasonally frozen soil region, provided as an embodiment of the present invention.

[0058] Figure 2This is a schematic diagram of a temperature change curve provided for an embodiment of the present invention.

[0059] Figure 3 This is a schematic diagram of the grounding device and the geometric model of the current dissipation area in the frozen soil region provided in an embodiment of the present invention.

[0060] Figure 4 This is a schematic diagram of failure curves for grounding devices made of different materials provided in the embodiments of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0062] Figure 1 A flowchart illustrating a failure assessment method for power pole grounding devices in seasonally frozen soil areas, provided as an embodiment of the present invention. (See attached diagram.) Figure 2 The failure assessment method includes:

[0063] S1. Obtain frozen soil test data at the location of the target tower in the seasonally frozen soil area, and establish a temperature change curve based on the frozen soil test data.

[0064] Permafrost experimental data can include different questions and the resistivity of permafrost at different temperatures.

[0065] Optionally, this embodiment of the invention provides an example of obtaining a temperature change curve, which may include: placing frozen soil and a temperature sensor in a cubic sand box with an inner diameter of 20 cm, and freezing it in a low-temperature test chamber. Temperature sensor data is recorded at different times. If a set temperature is reached, the soil resistivity is measured using the four-electrode method, and a temperature change curve is constructed based on the soil resistivity.

[0066] S2. Based on the temperature change curve, the soil is divided into zones using a multi-zone strategy to obtain the corresponding zone resistivity of the soil in different zones.

[0067] The soil resistivity zoning method can be as follows: divide the soil into three zones, where the first zone line separates frozen soil from thawed soil, and the second zone line is the temperature point where the increase in soil resistivity slows down.

[0068] S3. Establish the current dissipation failure model corresponding to the grounding device on the target tower, and obtain the failure curve corresponding to the grounding device on the target tower based on the corresponding zone resistivity of soil in different zones and the current dissipation failure model.

[0069] The process of establishing the current dissipation model can be as follows: First, establish a soil hydrothermal field coupling model that considers the heat transfer of the grounding conductor, calculate the soil structure under different freezing times, and then extract the structure and establish a grounding device impact current dissipation failure model.

[0070] S4. Based on the failure curve corresponding to the target tower, conduct a failure assessment on the grounding device on the target tower in the seasonally frozen soil area and obtain the failure assessment results.

[0071] The failure curve can be constructed by using a current-dissipating model to calculate the failure curve under different grounding device sizes, soil temperatures, and device materials.

[0072] Figure 2 This is a schematic diagram of a temperature change curve provided in an embodiment of the present invention. The method for obtaining this temperature change curve is as follows.

[0073] In one possible implementation, frozen soil test data is obtained at the location of the target tower in a seasonally frozen soil region, and a temperature change curve is established based on the frozen soil test data, including:

[0074] Obtain frozen soil test data at the location of the target tower in a seasonally frozen soil region. The frozen soil test data includes the resistivity of the frozen soil at different temperatures. For example, frozen soil test data can be obtained by selecting soil around the grounding device near the tower in a seasonally frozen soil region and conducting tests using laboratory experimental equipment such as a low-temperature test chamber.

[0075] Based on the resistivity of frozen soil at different temperatures and the resistivity corresponding to different temperatures, a curve of resistivity changing with temperature is constructed to obtain the temperature change curve.

[0076] In one possible implementation, based on the temperature change curve, the soil is divided into zones using a multi-zone strategy to obtain the corresponding zone resistivity of the soil in different zones, including:

[0077] Based on the temperature change curve, a first partition line and a second partition line are determined. The first partition line is used to separate frozen soil from thawed soil. The second partition line is used to separate resistivity increasing trends when the temperature continues to decrease. That is, when the increase in resistivity between two consecutive data points is less than a preset threshold, the previous data point can be used as the second partition line.

[0078] The first soil zone is determined based on the preset first interval length and the first zone line. For example, the first soil zone can be obtained by taking the preset first interval length upward from the first zone line.

[0079] Based on the first and second zoning lines, a second soil zoning is determined. For example, a second soil zoning can be randomly determined between the first and second zoning lines within a preset third interval length.

[0080] The third soil zone is determined based on the preset second interval length and the second zone line. For example, the third soil zone can be obtained by taking the preset second interval length downwards from the second zone line.

[0081] Optionally, the first and second zoning lines can be displayed to staff, and staff can input the first, second, and third soil zoning through human-computer interaction.

[0082] For the first soil zone, the second soil zone, the third soil zone, and the temperature change curve, the resistivity of each soil zone was determined by the geometric mean method, thereby obtaining the corresponding zone resistivity of the soil in different zones.

[0083] To simplify the calculation process, the resistivity versus temperature curve is divided into three intervals. Therefore, this invention is based on... Figure 2 The soil temperature-resistivity curve (i.e., temperature change curve) was used to divide the soil structure into zones and set the corresponding resistivity for each zone. The study shows that the soil at freezing temperature T... f Before and after freezing, the resistivity changes significantly. Therefore, the soil structure is initially divided into zones based on the freezing temperature. The first zoning line is the T = -0.5℃ isotherm, separating frozen soil from thawed soil. Figure 2 The resistivity of the frozen soil within the temperature range (T = -0.5, 4]℃ is set to ρ³ = 100 Ω*m. When the soil temperature falls below the freezing point and begins to freeze, its resistivity rises rapidly. To further refine the zoning of the frozen soil structure, a temperature range of [T = -10, T...]℃ is set. x The resistivity of frozen soil at ℃ is ρ1, and the temperature range is [T]. x T f The resistivity of frozen soil at ℃ is ρ2. In this invention, T is set... x = -4℃. This is because in Figure 2 When the temperature is below -4℃, the upward trend of soil resistivity slows down, so -4℃ is a relatively accurate dividing point.

[0084] according to Figure 2 The resistivity of the frozen soil in the corresponding segmented areas was set using the geometric mean method, with ρ1 = 7092 Ω*m and ρ2 = 2023 Ω*m, respectively. The calculation formula is shown below:

[0085]

[0086] Where, ρT＝-10 ρ represents the resistivity at -10℃. T＝-4 ρ represents the resistivity at -4℃. T＝-0.7 This indicates the resistivity at -0.7℃.

[0087] In one possible implementation, a current-spreading failure model corresponding to the grounding device on the target tower is established, and based on the corresponding regional resistivity of soil in different zones and the current-spreading failure model, the failure curve corresponding to the grounding device on the target tower is obtained, including:

[0088] By combining the heat transfer equations of the grounding conductor, the soil, and Darcy's law, and incorporating Dirichlet boundary conditions, a hydrothermal field coupling model considering heat transfer in the grounding conductor was established.

[0089] The spatiotemporal distribution of soil internal temperature was determined using this hydrothermal field coupling model, and the soil structure under different freezing times was obtained.

[0090] Based on soil structures under different freezing times and grounding devices on target towers, a current-spreading failure model is constructed. This current-spreading failure model is used as a simulation model to characterize the grounding device and its surrounding environment.

[0091] Figure 3 This is a schematic diagram of the grounding device and the geometric model of the current dissipation area in the permafrost region provided in an embodiment of the present invention. The permafrost layer farther from the grounding device is relatively horizontal, while the part closer to the grounding device forms a localized frozen structure around the grounding electrode due to the heat transfer effect of the grounding conductor. Based on this, the failure curve can be obtained. In the figure, ε represents the dielectric constant.

[0092] Multiple evenly distributed potential probes are arranged on the grounding device, and a positive current is injected into the top surface of the grounding device. The transient potential peak value is obtained through the potential probes.

[0093] Based on the transient potential peak value, the resistance change curve of the impulse grounding resistance of the grounding device with respect to time is obtained, and the resistance change curve of the grounding device on the target tower is obtained.

[0094] Based on the corresponding resistivity of soil in different zones, the impulse grounding resistance at the time of failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance at the time of failure.

[0095] Figure 4 The above diagram shows the failure curves of grounding devices made of different materials provided in the embodiments of the present invention. By comparing the failure curves with the actual situation, the failure status of the actual device can be determined.

[0096] In one possible implementation, multiple uniformly distributed potential probes are arranged on the grounding device, a positive current is injected into the top surface of the grounding device, and transient potential peaks are obtained through the potential probes, including:

[0097] Multiple evenly distributed potential probes are arranged on the grounding device.

[0098] Injecting a positive current onto the top surface of the grounding device is as follows:

[0099]

[0100]

[0101] Where I(t) represents the positive current, kA. p η represents the peak current, kA. η represents the peak correction factor. t represents time, μs. τ1 represents the wavefront time, μs. τ2 represents the wave tail time, μs. n represents the integral coefficient.

[0102] The voltage is detected by multiple uniformly distributed potential probes, and the maximum voltage value detected is taken as the transient potential peak value.

[0103] In one possible implementation, based on the transient potential peak value, the resistance change curve of the grounding device's impulse grounding resistance with respect to time is obtained, resulting in the resistance change curve corresponding to the grounding device on the target tower, including:

[0104] Based on the transient potential peak value, the impulse grounding resistance of the grounding device is obtained as follows:

[0105]

[0106] Among them, R ch This represents the impulse grounding resistance, expressed in Ω (V). p This represents the peak value of the transient potential, in kV.

[0107] Using time t as a variable, the resistance change curve of the impulse grounding resistance of the grounding device with respect to time is obtained, thus obtaining the resistance change curve of the grounding device on the target tower.

[0108] In one possible implementation, based on the corresponding resistivity of soil in different zones, the impulse grounding resistance at the time of failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance at the time of failure, including:

[0109] Based on the impulse grounding resistance of the grounding device, the corresponding average resistivity is obtained.

[0110] Based on the corresponding resistivity of the soil in different zones, determine whether the average resistivity meets the failure condition. If so, determine that the impulse grounding resistance corresponding to the average resistivity is the impulse grounding resistance corresponding to the failure condition; otherwise, determine that it has not failed.

[0111] Iterate through the impulse grounding resistance corresponding to each time point to obtain the impulse grounding resistance corresponding to all failures.

[0112] Based on the impulse grounding resistance corresponding to the failure point, the failure point is marked on the resistance change curve to obtain the failure curve.

[0113] In one possible implementation, when the frozen soil wraps around the end of the grounding conductor, R ch A sudden surge is expected.

[0114] Based on the impulse grounding resistance of the grounding device, the corresponding average resistivity is obtained as follows:

[0115]

[0116] in, The value represents the average resistivity, in Ω*m. π represents pi (the mathematical constant for a circle). l represents the length of the vertical grounding electrode of the grounding system, in meters. d represents the radius of the vertical grounding electrode, in meters.

[0117] In one possible implementation, determining whether the average resistivity meets the failure condition based on the corresponding zone resistivity of the soil in different zones includes:

[0118] Based on the corresponding resistivity of the soil in different zones, the failure impact factor is obtained as follows:

[0119]

[0120] Where α represents the failure impact factor. ρ2 represents the resistivity of the second soil zone, in Ω*m. ρ3 represents the resistivity of the third soil zone, in Ω*m.

[0121] The system determines whether the failure impact factor exceeds a preset threshold. If it does, the failure condition is met; otherwise, it is not. For example, when α = 0, the equivalent resistivity of the soil is consistent with the actual resistivity of the unfrozen soil, indicating that the soil freezing process has not yet begun. When α ≥ 0.5, it can be considered that the second layer of soil has completely enveloped the grounding conductor and hindered normal current dissipation, thus indicating that the grounding device has failed.

[0122] In one possible implementation, it also includes:

[0123] judge If the condition is met, the grounding device is deemed to be obsolete and an alarm message is generated; otherwise, the failure assessment continues.

[0124] This invention provides a failure assessment method for grounding devices on poles in seasonally frozen soil areas. By establishing a temperature change curve and using it as a basis, the corresponding resistivity of soil in different zones is obtained. Then, a current-spreading failure model is established for the grounding device on the target pole. Based on the corresponding resistivity of soil in different zones and the current-spreading failure model, the failure curve for the grounding device on the target pole can be obtained. Finally, based on the failure curve of the target pole, the failure state of the grounding device on poles in seasonally frozen soil areas can be assessed. This method can effectively determine the operating status of the grounding device and allow for targeted measures to reduce the damage caused by lightning current, demonstrating significant engineering value.

[0125] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for assessing the failure of grounding devices for power poles in seasonally frozen soil areas, characterized in that, include: Obtain frozen soil test data at the location of the target tower in a seasonally frozen soil region, and establish a temperature change curve based on the frozen soil test data; Based on the temperature change curve, a multi-zone strategy is used to divide the soil into zones to obtain the zone resistivity corresponding to different zones. This includes: determining a first zone line and a second zone line based on the temperature change curve; the first zone line is used to separate frozen soil from thawed soil; the second zone line is used to separate resistivity increasing trends when the temperature continues to decrease, i.e., when the increase in resistivity between two consecutive data points is less than a preset threshold, the previous data point can be used as the second zone line; determining a first soil zone based on a preset first interval length and the first zone line; determining a second soil zone based on the first and second zone lines; determining a third soil zone based on a preset second interval length and the second zone line; and determining the resistivity of each soil zone using the geometric mean method for the first, second, and third soil zones and the temperature change curve, thereby obtaining the zone resistivity corresponding to different soil zones. A current-diffusing failure model corresponding to the grounding device on the target tower was established. Based on the regional resistivity of soil in different zones and the current-diffusing failure model, the failure curves corresponding to the grounding device on the target tower were obtained. This included: establishing a hydrothermal field coupling model considering heat transfer of the grounding conductor by simultaneously solving the heat transfer equations of the grounding conductor, the soil heat transfer equations, and Darcy's law, and combining Dirichlet boundary conditions; determining the spatiotemporal distribution of soil internal temperature through this hydrothermal field coupling model, and obtaining the soil structure under different freezing times; and constructing a current-diffusing failure model based on the soil structure under different freezing times and the grounding device on the target tower. The current-dissipating failure model is used to characterize the grounding device and the environment in which the grounding device is located. Multiple uniformly distributed potential probes are arranged on the grounding device, and a positive current is injected into the top surface of the grounding device. The transient potential peak value is obtained through the potential probes. Based on the transient potential peak value, the resistance change curve of the impulse grounding resistance of the grounding device with respect to time is obtained, and the resistance change curve of the grounding device on the target tower is obtained. Based on the zone resistivity of the soil in different zones, the impulse grounding resistance corresponding to the failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance corresponding to the failure. Based on the failure curves corresponding to the grounding devices on the target towers, a failure assessment of the grounding devices on the target towers in seasonally frozen soil areas is conducted to obtain the failure assessment results.

2. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 1, characterized in that, Obtain permafrost test data at the location of the target tower in a seasonally frozen soil region, and establish a temperature change curve based on the permafrost test data, including: Obtain frozen soil test data at the location of the target tower in a seasonally frozen soil region. The frozen soil test data includes different temperatures and the resistivity of the frozen soil at different temperatures. Based on the resistivity of frozen soil at different temperatures and the resistivity corresponding to different temperatures, a curve of resistivity changing with temperature is constructed to obtain the temperature change curve.

3. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 2, characterized in that, Multiple uniformly distributed potential probes are arranged on the grounding device. A positive current is injected into the top surface of the grounding device, and the transient potential peak value is obtained through the potential probes, including: Multiple evenly distributed potential probes are arranged on the grounding device; Injecting a positive current onto the top surface of the grounding device is as follows: ； ； in, Indicates positive current, kA; Indicates peak current, kA; Indicates the peak correction factor; Indicates time, in μs; Indicates wavefront time, in μs; The wave tail time is represented in μs; n represents the integral coefficient. The voltage is detected by multiple uniformly distributed potential probes, and the maximum voltage value detected is taken as the transient potential peak value.

4. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 3, characterized in that, Based on the transient potential peak value, the resistance variation curve of the grounding device's impulse grounding resistance with respect to time is obtained, resulting in the corresponding resistance variation curve of the grounding device on the target tower, including: Based on the transient potential peak value, the impulse grounding resistance of the grounding device is obtained as follows: ； in, Indicates impulse grounding resistance, in Ω; This represents the peak value of the transient potential, in kV. In time Using the variable as the reference, obtain the resistance change curve of the impulse grounding resistance of the grounding device with respect to time, and obtain the corresponding resistance change curve of the grounding device on the target tower.

5. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 4, characterized in that, Based on the resistivity of soil in different zones, the impulse grounding resistance at failure is determined, and a failure curve is constructed using the resistance change curve and the impulse grounding resistance at failure, including: Based on the impulse grounding resistance of the grounding device, the corresponding average resistivity is obtained; Based on the resistivity of the soil in different zones, determine whether the average resistivity meets the failure condition. If so, determine that the impulse grounding resistance corresponding to the average resistivity is the impulse grounding resistance corresponding to the failure condition; otherwise, determine that it has not failed. Iterate through the impulse grounding resistance corresponding to each time point to obtain the impulse grounding resistance corresponding to all failures. Based on the impulse grounding resistance corresponding to the failure point, the failure point is marked on the resistance change curve to obtain the failure curve.

6. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 5, characterized in that, Based on the impulse grounding resistance of the grounding device, the corresponding average resistivity is obtained as follows: ； in, The average resistivity is expressed in Ω*m. The length of the vertical grounding electrode of the grounding device is expressed in meters (m). The radius of the vertical grounding electrode is expressed in meters (m).

7. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 6, characterized in that, Based on the resistivity of soil in different zones, determine whether the average resistivity meets the failure criteria, including: Based on the resistivity of the soil in different zones, the failure impact factor is obtained as follows: ； in, Indicates the failure impact factor; This represents the resistivity of the second soil zone, in Ω*m; The resistivity of the third soil zone is represented in Ω*m. Determine whether the failure impact factor is greater than a preset threshold. If so, the failure condition is met; otherwise, the failure condition is not met.

8. The failure assessment method for tower grounding devices in seasonally frozen soil areas according to claim 7, characterized in that, Also includes: judge If the condition is met, the grounding device is deemed to be obsolete and an alarm message is generated; otherwise, the failure assessment continues.

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