Methods and apparatus for detecting thermal damage to overhead power lines

Abstract

This application provides a method and apparatus for detecting thermal damage to overhead power lines. The method includes: acquiring the resistance of a system under test, wherein the experimental platform includes the system under test and an excitation module connected thereto; controlling the excitation module to apply a power frequency current to the system under test to acquire a first duration for the system under test to reach a preset temperature and a second duration for the temperature sensing device to activate; determining, at least based on the resistance, a first heat and a second heat, wherein the first heat is the heat generated when the system under test reaches the preset temperature, and the second heat is the heat generated when the temperature sensing device activates; determining, based on the first heat and the second heat, whether the activation of the temperature sensing device meets accuracy requirements; and, if the activation of the temperature sensing device meets accuracy requirements, using the temperature sensing device to detect thermal damage to the overhead power line. This method at least addresses the problem of insufficient accuracy in detecting thermal defects in overhead power lines in the prior art.

Description

Technical Field

[0001] This application relates to the field of detecting thermal damage to overhead lines, and more specifically, to a method and apparatus for detecting thermal damage to overhead lines. Background Technology

[0002] Among power grid operational faults, overhead ground wire breakage due to lightning strikes is one of the most common permanent faults. Although overhead ground wires are the most basic and effective lightning protection measure for high-voltage transmission lines, they themselves are still at risk of breaking and falling when struck by lightning. Generally, it is extremely rare for a single lightning strike to directly cause a break; often, multiple lightning strikes cause strand damage, and the process from strand damage to a complete break is gradual. Timely detection of strand damage is crucial to prevent a break. Once a break occurs, the protective function for equipment is lost, potentially leading to equipment damage, cascading failures across multiple towers, and posing a significant threat to the surrounding environment. Therefore, timely detection and handling of potential breakage hazards are extremely important for the stable operation of the power grid and the safety of people's lives and property.

[0003] As a crucial line of defense against lightning strikes on high-voltage transmission lines, the ground wire is erected above the transmission line via suspension clamps. When lightning strikes the overhead ground wire, the lightning strikes the ground along the path from the ground wire to the suspension clamp and then to the tower. Prolonged exposure to lightning strikes can cause thermal damage to both the overhead ground wire and the suspension clamp. These damaged areas, exposed to wind, sun, and rain, may corrode, further weakening their mechanical strength and posing safety hazards. Therefore, it is essential to detect thermal damage and defects in the suspension clamp area.

[0004] Currently, the main methods for detecting thermal defects and damage in overhead lines in power grid systems are infrared thermography and infrared thermography. These two infrared detection technologies can accurately and efficiently predict and infer initial fault deviations and insulation conditions in electrical facilities, enabling the inspection and maintenance of electrical facilities to evolve from defensive maintenance to predictive maintenance. Furthermore, their application can be carried out without connection, power outage, or disassembly, achieving high efficiency. However, they also have significant limitations, such as limited measurement range, insufficient measurement accuracy, and susceptibility to environmental influences.

[0005] Existing technologies employ various experimental methods, but all suffer from intractable drawbacks. One method involves directly exciting the sample on the experimental platform with lightning current; however, existing excitation devices cannot fully simulate lightning current, and the immense energy of lightning current poses significant safety hazards. Another method employs finite element simulation, but this method cannot completely simulate actual conditions, requires quantification of experimental platform parameters, resulting in complex data and a large computational burden. Platform construction is also difficult, with poor adjustability of structural parameters, boundary conditions, and excitation settings, requiring substantial time and effort. A third method uses a constant-temperature chamber, but the physical processes within the chamber differ significantly from those during an actual lightning strike, leading to substantial errors compared to the short-duration high-temperature conditions of a lightning strike. Summary of the Invention

[0006] The main objective of this application is to provide a method and apparatus for detecting thermal damage to overhead lines, so as to at least solve the problem of insufficient accuracy in detecting thermal defects of overhead lines in the prior art.

[0007] To achieve the above objectives, according to one aspect of this application, a method for detecting thermal damage to overhead power lines is provided, comprising: acquiring the resistance of a system under test, wherein an experimental platform includes the system under test and an excitation module connected thereto; the system under test includes a temperature sensing device, a test element, and a pressure plate, the pressure plate being connected to the temperature sensing device and the test element; controlling the excitation module to apply a power frequency current to the system under test to acquire a first duration for the temperature of the system under test to reach a preset temperature and a second duration for the temperature sensing device to activate; determining a first heat and a second heat based at least on the resistance, wherein the first heat is the heat generated when the temperature of the system under test reaches the preset temperature, and the second heat is the heat generated when the temperature sensing device activates; determining whether the activation of the temperature sensing device meets accuracy requirements based on the first heat and the second heat; and, if the activation of the temperature sensing device meets the accuracy requirements, using the temperature sensing device to detect thermal damage to the overhead power line.

[0008] Optionally, determining the first heat and the second heat, at least based on the resistance, includes: based on the resistance and a first formula: The first heat Q1 is obtained, where I0 is the power frequency current, and R... 总 Let t1 be the resistance and t1 be the first duration; according to the resistance and the second formula: The second heat Q2 is obtained, where t2 is the second duration.

[0009] Optionally, determining whether the operation of the temperature sensing device meets the accuracy requirement based on the first heat and the second heat includes: based on the first heat, the second heat, and a third formula: The relative error σ is obtained; the relationship between the relative error σ and the first threshold is determined; if the relative error σ is less than the first threshold, the operation of the temperature sensing device meets the accuracy requirement.

[0010] Optionally, the method further includes: determining a third heat source based at least on the resistance, the third heat source being the heat generated by the temperature sensing device under the condition of passing a lightning current; determining a fourth heat source based at least on the first duration, the fourth heat source being the heat generated by the temperature sensing device under the condition of passing a power frequency current; and verifying whether the experimental platform meets the rationality requirements based on the third heat source and the fourth heat source.

[0011] Optionally, determining the third heat source based at least on the resistance includes: determining a fifth heat source based on the resistance and Joule's law, wherein the fifth heat source is the heat generated by the lightning current flowing through the system under test; determining a sixth heat source based on the resistance and Gaussian heat source model, wherein the sixth heat source is the heat generated by the system under test being partially broken down; and determining the third heat source based on the fifth heat source and the sixth heat source, wherein the third heat source is the sum of the fifth heat source and the sixth heat source.

[0012] Optionally, determining the fifth heat based on the resistance and Joule's law includes: based on the resistance and the fourth formula: The heat Q generated by the first conductive current is obtained A , among which, I p R is the amplitude of the leading current. 总 Let α be the resistance, β be the wavefront time of the lightning current, t be the half-peak time of the lightning current, t be the duration of the leading current, and t3 be the total duration of the leading current, wherein the lightning current includes the leading current and the continuous current; according to the resistance and the fifth formula: The heat Q generated by the continuous current is obtained. C , among which, I C t4 is the continuous current, and t4 is the total duration of the continuous current; according to the heat Q A and the heat Q C The fifth heat is obtained, wherein the fifth heat is the heat Q. A and the heat Q C sum.

[0013] Optionally, determining the fourth heat source based at least on the first duration includes: acquiring a first temperature, a second temperature, and a third temperature of the pressure plate, wherein the pressure plate has a first surface and a second surface, the first surface is in contact with the element under test, the second surface is in contact with air, the first temperature is the temperature of the first surface, the second temperature is the temperature of the second surface, and the third temperature is the temperature of the air; determining a seventh heat source based on the first duration, the first temperature, the second temperature, and the third temperature; and determining the fourth heat source based on the first heat source and the seventh heat source, wherein the fourth heat source is the difference between the first heat source and the seventh heat source.

[0014] Optionally, determining the seventh heat based on the first temperature, the second temperature, and the third temperature includes: based on the first temperature, the second temperature, and the sixth formula: The first heat loss q1 is obtained, where λ is the thermal conductivity of the material of the pressure plate, A1 is the area of ​​the contact surface between the pressure plate and the element under test, S is the thickness of the pressure plate, and ΔT1 is the difference between the first temperature and the second temperature. Based on the second temperature, the third temperature, and the seventh formula: q2 = aA2ΔT2, the second heat loss q2 is obtained, where a is the convective heat transfer coefficient, A2 is the contact area between the pressure plate and the air, and ΔT2 is the difference between the second temperature and the third temperature. Based on the first duration and the eighth formula: Q4 = (q1 + q2)t1, the seventh heat Q4 is obtained, where t1 is the first duration.

[0015] Optionally, based on the third heat and the fourth heat, verifying whether the experimental platform meets the rationality requirement includes: determining the relationship between the first difference and the second threshold, where the first difference is the absolute value of the difference between the third heat and the fourth heat; if the first difference is less than the second threshold, the experimental platform meets the rationality requirement.

[0016] According to another aspect of this application, a detection device for thermal damage of overhead power lines is provided, comprising: a first acquisition unit for acquiring the resistance of a system under test, wherein an experimental platform includes the system under test and an excitation module connected thereto, the system under test including a temperature sensing device, a test element, and a pressure plate, the pressure plate connecting the temperature sensing device and the test element; a control unit for controlling the excitation module to apply a power frequency current to the system under test to acquire a first duration for the temperature of the system under test to reach a preset temperature and a second duration for the temperature sensing device to activate; a determination unit for determining, at least based on the resistance, a first heat and a second heat, wherein the first heat is the heat generated when the temperature of the system under test reaches the preset temperature, and determining whether the activation of the temperature sensing device meets accuracy requirements; a judgment unit for determining, based on the first heat and the second heat, whether the activation of the temperature sensing device meets accuracy requirements; and a detection unit for detecting thermal damage of the overhead power line using the temperature sensing device if the activation of the temperature sensing device meets the accuracy requirements.

[0017] By applying the technical solution of this application, the accuracy and reliability of the temperature sensing device's operation are verified through an experimental platform, overcoming the shortcomings of existing experimental methods for testing thermal damage to overhead lines in power grid systems. The experimental platform includes the system under test (SUT) and an excitation module. The SUT includes a temperature sensing device, a test element, and a pressure plate. The pressure plate connects the temperature sensing device and the test element, acquiring the resistance of the SUT to increase detection accuracy. The excitation module applies a power frequency current to the SUT to obtain the first duration for the SUT's temperature to reach a preset temperature and the second duration for the temperature sensing device to activate. Using the power frequency current as the excitation current, the physical process of lightning current can be equivalently represented, as its current path is the same as that of lightning current. Furthermore, it can equivalently represent the heat generated at the sensing part during the lightning current's action, avoiding the high costs and harshness associated with artificial lightning strikes. To mitigate the risks associated with manual drainage, the method employs a specific approach. Based on the resistance, a first heat source and a second heat source are determined. The first heat source is the heat generated when the system under test reaches the preset temperature, and the second heat source is the heat generated when the temperature sensing device activates. Based on these two heat sources, the accuracy of the temperature sensing device's operation is assessed. Using power frequency current as the excitation, the heat generated when the device reaches its operating temperature is compared with the heat generated when the device activates, verifying the accuracy of the core temperature sensing element's operating temperature design. When the temperature sensing device's operation meets the accuracy requirements, it is used to detect thermal damage to the overhead line. Using a temperature sensing device that meets accuracy standards simplifies the detection method and increases its accuracy. This method, using power frequency current as the excitation, provides an equivalent heat experiment that can represent the physical process of lightning current. Its current path is the same as the lightning current path, and it can represent the heat generated at the sensing point during the lightning current's action. Furthermore, this experimental method offers advantages such as low cost, convenient operation, and a high safety factor. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0019] Figure 1 A hardware structure block diagram of a mobile terminal for performing a method for detecting thermal damage to overhead lines, according to an embodiment of this application, is shown.

[0020] Figure 2 A schematic flowchart of a method for detecting thermal damage to overhead lines according to an embodiment of this application is shown.

[0021] Figure 3A structural diagram of a component under test provided according to an embodiment of this application is shown;

[0022] Figure 4 A structural diagram of a temperature sensing device and a pressure plate provided according to an embodiment of this application is shown;

[0023] Figure 5 A structural diagram of another temperature sensing device provided according to an embodiment of this application is shown;

[0024] Figure 6 A structural diagram of a temperature sensing device in the case of lever lock unlocking, according to an embodiment of this application, is shown.

[0025] Figure 7 A structural diagram of the temperature sensing device structure provided according to an embodiment of this application in the case where the lever lock is disengaged from the slot is shown.

[0026] Figure 8 A structural block diagram of an overhead line thermal damage detection device provided according to an embodiment of this application is shown.

[0027] The above figures include the following reference numerals:

[0028] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device; 301. Ground wire; 302. Aluminum cladding strip; 303. Pressure plate; 304. Hanging plate; 305. Current line; 306. Temperature sensing device; 401. Bimetallic strip; 402. Lever lock; 403. Spring; 404. Metal jacket; 4041. Upper metal sleeve; 4042. Lower metal sleeve; 405. Red warning device. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] 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.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying 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 for the embodiments of this application 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.

[0032] As described in the background section, various experimental methods can be used to detect thermal damage to overhead lines in the prior art, but all have intractable drawbacks. One method is to directly excite the sample on the experimental platform using lightning current, but existing excitation devices cannot fully simulate lightning current, and the energy of lightning current is enormous, posing significant safety hazards. Another method is to use finite element simulation, but this method cannot fully simulate the actual situation, requires quantification of the experimental platform parameters, resulting in complex data and a large computational load. The platform is also difficult to build, with poor adjustability of structural parameters, boundary conditions, and excitation settings, requiring a significant investment of time and effort. Yet another method is to use a constant temperature chamber, but the physical processes within the chamber differ greatly from those during an actual lightning strike, leading to substantial errors compared to the short-term high temperatures of a lightning strike. To address the aforementioned technical problems, embodiments of this application provide a method and apparatus for detecting thermal damage to overhead lines.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a method of detecting thermal damage to overhead power lines according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0035] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the overhead line thermal damage detection method in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0036] This embodiment provides a method for detecting thermal damage to overhead lines that runs on a mobile terminal, computer terminal, or similar computing device. 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. 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.

[0037] Specifically, an existing patent designs an intelligent passive detection device for short-term high temperatures in suspension clamps based on finite element simulation, as shown in the figure below. This detection device uses a bimetallic strip as the core temperature-sensing element to quickly detect the transient process of abnormal temperature rise caused by lightning current acting on the suspension clamp. The device's operating mechanism is as follows: based on the characteristics of the bimetallic strip, the two metal layers expand to different degrees when heated. The bimetallic strip bends, unlocking the lever lock, and the spring action pops out the alarm. After troubleshooting, the alarm can be reset and reused. Regarding the design of the device's operating temperature, this patent uses finite element simulation to simulate and model the short-term high temperature caused by lightning strikes. This includes establishing a geometric model of the ground wire-clamp assembly wrapped with aluminum tape, setting material property parameters, and model boundary conditions. Based on the simulation results of the short-term high temperature caused by lightning strikes and the calculation and analysis of the decrease in tensile strength of overhead ground wires with temperature, combined with the ambient temperature value of long-term outdoor operation in summer, a corresponding operating temperature value, i.e., the temperature-sensing operating threshold, can be selected.

[0038] The current requirement is to employ an experimental method to verify that the designed intelligent passive detection device is suitable for practical application and can achieve the expected results in detecting short-term high-temperature thermal defects. As can be seen above, the core component of the intelligent passive detection device is the temperature sensing element; therefore, only an experimental method needs to be designed to calibrate the temperature sensing element and verify its accuracy and reliability. Several existing methods may achieve the experimental objective, but all have shortcomings:

[0039] Method 1 involves using an impulse current generator to build a lightning current simulation experimental platform. However, existing excitation devices can only simulate direct lightning current damage and cannot simulate the damage caused by lightning current flowing through the clamp after being injected into the ground wire.

[0040] Method two, which uses artificial lightning, can recreate the actual physical scene, but it is expensive and can only be tested outdoors during thunderstorm season, which is very demanding.

[0041] Method three is to use the finite element simulation method. However, this method cannot fully simulate the actual situation. In particular, it requires quantitative processing of the experimental platform parameters, which results in a large amount of computation and poor adjustability of structural parameters, boundary conditions, and excitation settings.

[0042] Method four uses a constant temperature chamber for testing. The disadvantage is that the constant temperature chamber mainly uses air for heat transfer, which causes the temperature change of the sample inside the chamber to be very different from the physical process of temperature change inside the clamp during an actual lightning strike. This will produce a large error compared to the short-term high temperature of a lightning strike.

[0043] Figure 2 This is a flowchart of a method for detecting thermal damage to overhead power lines according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0044] Step S201: Obtain the resistance of the system under test. The experimental platform includes the system under test and the excitation module. The system under test includes a temperature sensing device, a component under test, and a pressure plate. The pressure plate is connected to the temperature sensing device and the component under test.

[0045] Specifically, the resistance of the system under test can be obtained using a black-box experiment. This involves treating the components corresponding to the resistance as a whole, applying an external excitation, measuring the response, and then calculating the corresponding value. Existing impedance measuring instruments and the bridge method for measuring resistance can be used to perform this black-box experiment. Calculating heat based on the resistance of the component under test not only simplifies the experimental platform but also increases the accuracy of the detection.

[0046] Step S202: Control the excitation module to apply power frequency current to the system under test in order to obtain the first duration for the temperature of the system under test to reach the preset temperature and the second duration for the temperature sensing device to activate.

[0047] Specifically, power frequency current refers to the frequency of mains electricity (industrial electricity), a type of alternating current with a relatively low frequency, typically 50 Hz or 60 Hz. The stable frequency and waveform of power frequency current are beneficial for the stable operation of power systems and the normal operation of equipment. The heat equivalent experimental method using power frequency current as excitation can equivalently represent the physical process of lightning current, with its current path being the same as that of lightning current. This avoids the high costs and harsh conditions associated with artificial lightning strikes and reduces the dangers of manual current induction.

[0048] Step S203: Determine the first heat and the second heat based at least on the resistance, wherein the first heat is the heat generated when the temperature of the system under test reaches the preset temperature, and the second heat is the heat generated by the system under test when the temperature sensing device is activated.

[0049] Specifically, an experimental platform was established using power frequency current as excitation and the suspension clamp-ground wire system as the excitation object. The ground wire, the contact resistance of the ground wire and the aluminum sheath, and the aluminum sheath are all incorporated into the current loop. On this experimental platform, the heat generated to reach the designed operating temperature of the system under test under power frequency current excitation is the first type of heat. The heat generated at the point where the temperature sensing device needs to activate under power frequency current is the second type of heat. By obtaining the theoretical heat required for the system to reach its operating temperature and the actual heat required for the temperature sensing device to activate, the experimental process is simplified, the experimental cost is reduced, operation is convenient, and the safety factor is high.

[0050] Step S204: Based on the first heat and the second heat, determine whether the operation of the temperature sensing device meets the accuracy requirements.

[0051] Specifically, the first and second heat obtained under this experimental method are kept within a specified error range so that the error of the temperature sensing device is within a controllable range. Furthermore, the error setting can be adjusted according to the user's needs, thereby improving the user experience while accurately and reliably determining whether the operating temperature setting of the temperature sensing device needs to meet the requirements.

[0052] Step S205: If the operation of the temperature sensing device meets the accuracy requirements, the temperature sensing device is used to detect thermal damage to the overhead line.

[0053] Specifically, using power frequency current as the current excitation, the heat generated when the device reaches its operating temperature and the heat generated when the device operates are compared and analyzed to verify the accuracy of the operating temperature design of the core temperature sensing element. Under the condition that the operation of the temperature sensing device meets the accuracy requirements, the temperature sensing device is used to detect thermal damage to overhead lines. Using a temperature sensing device that meets the accuracy requirements to detect thermal damage and thermal defects of overhead lines simplifies the detection method and increases the accuracy of the detection.

[0054] This embodiment overcomes the shortcomings of existing experimental methods for testing thermal damage to overhead lines in power grid systems by constructing an experimental platform to verify the accuracy and reliability of the temperature sensing device. The experimental platform includes a system under test (SUT) and an excitation module. The SUT includes a temperature sensing device, a test element (TI), and a pressure plate. The pressure plate connects the temperature sensing device and the TTI to obtain the resistance of the SUT, increasing the accuracy of the detection. The excitation module applies a power frequency current to the SUT to obtain the first duration for the SUT to reach a preset temperature and the second duration for the temperature sensing device to activate. Using the power frequency current as the excitation current can equivalently represent the physical process of lightning current, as its current path is the same as that of lightning current, and it can also equivalently represent the heat generated at the sensing part during the lightning current's action, avoiding the high costs associated with artificial lightning strikes. This method minimizes the risks associated with manual heat transfer under stringent conditions. It determines the first and second heat sources based on resistance. The first heat source is the heat generated when the system reaches a preset temperature, and the second heat source is the heat generated when the temperature sensing device activates. Based on these two heat sources, the accuracy of the temperature sensing device's operation is assessed. Using power frequency current as the excitation, the heat generated when the device reaches its activation temperature is compared with the heat generated when the device activates, verifying the accuracy of the core temperature sensing element's activation temperature design. When the temperature sensing device's operation meets accuracy requirements, it is used to detect thermal damage to overhead lines. Using an accurate temperature sensing device to detect thermal damage and defects in overhead lines simplifies the detection method and increases accuracy. The above method, using power frequency current as the excitation, is a heat equivalent experiment that can equivalently represent the physical process of lightning current, with the current path being the same as the lightning current path, and can equivalently represent the heat generated at the sensing part during the lightning current's action. This experimental method also has advantages such as low cost, convenient operation, and high safety factor.

[0055] Existing technologies employ various experimental methods, but all suffer from intractable drawbacks. One method involves directly exciting the sample on the experimental platform with lightning current; however, existing excitation devices cannot fully simulate lightning current, and the immense energy of lightning current poses significant safety hazards. Another method employs finite element simulation, but this method cannot completely simulate actual conditions, requiring quantification of experimental platform parameters, resulting in complex data and a large computational burden. Platform construction is also difficult, with poor adjustability of structural parameters, boundary conditions, and excitation settings, demanding substantial time and effort. A third method uses a constant temperature chamber, but the physical processes within the chamber differ significantly from those during actual lightning strikes, leading to substantial errors compared to the short-duration high temperatures of a lightning strike. To address these shortcomings, this patent proposes a thermal equivalence experimental method using power frequency current as excitation. This method can equivalently represent the physical process of lightning current, with the current path mirroring the lightning current path and effectively representing the heat generated at the sensing point during the lightning current's action. Furthermore, this experimental method offers advantages such as low cost, ease of operation, and a high safety factor.

[0056] The geometric model of the aforementioned experimental platform includes the system under test, namely the suspension clamp-ground wire system sample, such as... Figure 3 As shown, it includes a ground wire 301, an aluminum cladding strip 302, a pressure plate 303, a hanging plate 304, and a current line 305.

[0057] The aforementioned experimental platform also includes a section of wire strand, a section of aluminum sheathing tape, a suspension clamp, a set of temperature sensing devices, a high current generator, a thermocouple temperature measuring device, and a support for fixing.

[0058] The current excitation source is a high-current generator, connected to the experimental sample via a large-section copper wire capable of carrying hundreds of amperes. One end of the copper wire is connected to the wire strands, and the other end is connected to the suspension clamp plate, specifically at the locations of ground wire 301 and plate 304. The high-current generator consists of two parts: a generation circuit and a control circuit. The generation circuit comprises a 220V AC power supply, a voltage regulator, and a fixed-ratio step-down transformer. The 220V AC power supply powers the voltage regulator, which in turn powers the step-down transformer. The secondary side of the step-down transformer serves as the high-current output port, amplifying the current. The control circuit controls the lever action of the voltage regulator. By adjusting the lever, the voltage supplied by the voltage regulator to the primary side of the step-down transformer is changed, thereby controlling the output voltage and current on the secondary side of the step-down transformer, achieving current regulation. The excitation object is a sample constructed using experimental materials. Figure 3 The suspended clamp-ground system sample is shown. The temperature-sensing actuator is mounted at position 303 of the pressure plate, as shown. Figure 4 As shown. The thermocouple temperature measuring device is laid on the contact surface between the pressure plate 303 and the temperature sensing device 306, and on the contact surface between the pressure plate 303 and the aluminum sheath. Specifically, the temperature sensing device is as follows: Figure 5 As shown, a thermo-deformable bimetallic strip is used as the core temperature-sensing material. Utilizing the different thermal expansion rates of different metals during temperature changes, the bimetallic strip bends towards the side with the lower thermal expansion rate when heated, thus achieving a mechanical action.

[0059] like Figure 6 As shown, the main body of the temperature sensing device consists of a bimetallic strip 401 as the core temperature-sensing actuating element, a lever lock 402, a spring 403 as the indicating actuating element, a metal jacket 404, and a red warning device 405. Figure 7 As shown, the metal sleeve 404 includes an upper metal sleeve 4041 and a lower metal sleeve 4042. From bottom to top, the lower metal sleeve 4042 contains a bimetallic strip 401, a lever lock 402, a spring (located inside the metal sleeve 404 in the figure, not shown), and a red warning device 405. The lower metal sleeve 4042 is then threadedly connected to the upper metal sleeve 4041. The lower end of the lever presses against the bimetallic strip 401, and the upper end locks the red warning device 405. The spring is also located between the red warning device 405 and the bimetallic strip 401, and is normally in a compressed state. The upper metal sleeve 4041 has a hole to allow the red warning device 405 to pop out after activation. The lower end of the red warning device 405 has a tube clamp to lock the spring after it pops out. When the temperature at the bottom rises to a preset temperature (thermal defect temperature),... When the bimetallic strip at the bottom of the temperature sensing core is heated, the two metal layers expand to different degrees due to the characteristics of the bimetallic strip. The bimetallic strip bends, which unlocks the lever lock, causing the lever lock to disengage from the slot. The spring releases its elastic force upward, causing the red alarm to pop out, thus realizing the alarm function.

[0060] In the specific implementation process, the first heat and the second heat are determined at least based on the resistance, including: based on the resistance and the first formula: The first heat Q1 is obtained, where I0 is the power frequency current and R... 总 Let t1 be the resistance, and t1 be the first duration; according to the resistance and the second formula: The second heat Q2 is obtained, where t2 is the second duration.

[0061] In the above embodiments, according to Joule's law, the corresponding heat can be obtained simply by acquiring the experimental time. During the experiment, the duration is relatively easy to obtain, and the obtained heat is also relatively accurate for the duration, reducing the operational difficulty of the experimental platform, improving its accuracy, and simultaneously reducing its cost.

[0062] Specifically, to improve the accuracy of duration acquisition, multiple first durations and multiple second durations are acquired on the experimental platform under the same conditions. A target first duration is obtained from the multiple first durations, and a target second duration is obtained from the multiple second durations. The target first duration is then updated to the first duration to acquire the first heat, and the target second duration is then updated to the second duration to acquire the second heat. Here, the target first duration is the average of the multiple first durations, and the target second duration is the average of the multiple second durations. The first heat is calculated using the target first duration, and the second heat is calculated using the target second duration, thereby reducing experimental errors and increasing the accuracy of detection.

[0063] In the specific implementation process, based on the first heat and the second heat, it is determined whether the operation of the temperature sensing device meets the accuracy requirements, including: based on the first heat, the second heat, and the third formula: Obtain the relative error σ; determine the relationship between the relative error σ and the first threshold; if the relative error σ is less than the first threshold, the operation of the temperature sensing device meets the accuracy requirements.

[0064] In the above embodiments, using power frequency current as the current excitation, the heat generated when the device reaches its operating temperature and the heat generated when the device activates are compared and analyzed to verify the accuracy of the operating temperature design of the core temperature sensing element. By setting a first threshold to determine whether the operation of the temperature sensing device meets the accuracy requirements, the experimental difficulty is reduced. Furthermore, the error setting can be adjusted according to user needs, improving the user experience while accurately and reliably determining whether the operating temperature setting of the temperature sensing device meets the requirements.

[0065] In the specific implementation process, the method also includes: determining the third heat based at least on the resistance, the third heat being the heat generated by the temperature sensing device under the condition of passing lightning current; determining the fourth heat based at least on the first duration, the fourth heat being the heat generated by the temperature sensing device under the condition of passing power frequency current; and verifying whether the experimental platform meets the rationality requirements based on the third heat and the fourth heat.

[0066] In the above embodiments, mathematical models are established for the heat energy and temperature generated by the ground wire-suspension clamp assembly under the action of lightning current and power frequency current, respectively. The effects of both on the temperature sensing element are then equated by combining the experimental results under power frequency current. A comparison is made between the heat generated by the system under test under lightning current and the heat generated by the temperature sensing device under power frequency current to determine the rationality of the experimental platform. If the experimental platform meets the rationality requirements, the accuracy of the temperature sensing device is assessed, further enhancing the platform's ability to judge the accuracy of the temperature sensing device. If the experimental platform does not meet the rationality requirements, further adjustments are made to obtain a reasonable power frequency current.

[0067] In the specific implementation process, at least based on the resistance, the third heat is determined, including: the fifth heat is determined based on the resistance and Joule's law, wherein the fifth heat is the heat generated by the lightning current flowing through the system under test; the sixth heat is determined based on the resistance and Gaussian heat source model, wherein the sixth heat is the heat generated by the local breakdown of the system under test; and the third heat is determined based on the fifth heat and the sixth heat, wherein the third heat is the sum of the fifth heat and the sixth heat.

[0068] In the above embodiments, lightning breakdown is a complex process that generates various types of heat. In these embodiments, based on the characteristics of lightning current, the heat generated by the system under test under lightning current conditions is obtained, including the heat mainly generated under the action of lightning current, as well as the heat generated by internal breakdown caused by lightning current. This simplifies the experimental procedure while ensuring the accuracy of the experiment.

[0069] Specifically, the lightning current enters from the point of impact, flows sequentially through the ground wire, aluminum sheathing, suspension clamp, fasteners, grounding tower, and finally into the earth. According to existing aircraft lightning protection and testing standards, the standard lightning current waveform has four stages: initial conduction current, intermediate current, continuous DC, and final impulse current. The fifth heat source can be calculated based on the lightning current waveform. Simultaneously, localized breakdown near the ground wire-clamp contact point generates an electric arc discharge. Therefore, the heat generated by the lightning current within the components, resulting in localized high temperatures, is partly Joule heating and partly arc heating.

[0070] In the specific implementation process, the fifth heat is determined based on resistance and Joule's law, including: based on resistance and the fourth formula: The heat Q generated by the first conductive current is obtained A , among which, I p R is the amplitude of the initial current. 总 Let be the resistance, α be the wavefront time of the lightning current, β be the half-peak time of the lightning current, t be the duration of the preceding current, and t3 be the total duration of the preceding current. The lightning current includes both the preceding current and the continuous current. Based on the resistance and the fifth formula: The heat Q generated by the continuous current is obtained C , among which, I C Let t4 be the continuous current, and t4 be the total duration of the continuous current; based on the heat Q... A And calories Q C The fifth calorie is obtained, where the fifth calorie is calorie Q. A And calories Q C sum.

[0071] Specifically, the Joule heat source and the arc heat source generated by the high-frequency pulse component and DC component of the lightning current are modeled and described as follows: For the high-frequency pulse component A, a double exponential function model is used for mathematical description: iA (t)=I P (e -αt -e β- ) t In the formula, I p The amplitude of the A-component of the lightning current is represented by α. Studies of lightning current waveforms and their expressions show that the parameters α and β can be calculated using existing formulas based on the wavefront time and half-peak time of the lightning current. For example, if the national standard specifies a wavefront / half-peak time constant of 1.2 / 50 μs (wavefront time / half-peak time), the values ​​of α and β can be calculated using existing methods to be 1.473 × 10⁴ and 2.08 × 10⁶, respectively. The total duration of the A-component of the lightning current is set to t³. Considering the rapid decay rate of the A-component, t³ can be set to 500 μs, at which point the magnitude of the A-component is approximately 10% of its peak value.

[0072] The DC component C can be directly described mathematically using a square wave, with the current magnitude being I. C The action time is t4, and the generated electric arc heat source is mathematically described using a Gaussian heat source model:

[0073]

[0074] In the formula, I C R(t) represents the DC component of the lightning current, R(t) represents the maximum radius of the Gaussian heat source, and r represents the radius of the electric arc heat source.

[0075] The Joule heating and arc heating generated by the lightning current are calculated using the model formulas given above: the total resistance of the lightning current through the ground wire-suspension clamp assembly path is taken as R. 总 The heat generation of the A component of the lightning current was calculated using Joule's law: Heat generated by the C component of lightning current: The total Joule heat generated, i.e., the fifth heat, is: Q5 = Q A +Q C .

[0076] In the above embodiment, the fifth heat is the heat generated by the lightning current flowing through the system under test. The standard lightning current waveform has four stages: initial current, intermediate current, continuous DC, and re-impact current. According to relevant research on direct damage from lightning strikes to OPGW lines, the main contributing components to the damage to metallic materials caused by lightning strikes are the initial current (A component), which leaves a large number of charge carriers in the metallic material, and the continuous current (C component), which injects a large amount of transferred charge into the metal. Therefore, considering only the influence of the A and C components on the heating of the ground wire-clamp assembly, by obtaining the heat generated by the initial current (A) and the continuous current (C), the heat generated by the lightning current flowing through the system under test can be obtained. This allows for a scientific determination of the heat generated by the lightning current flowing through the system under test, further obtaining accurate heat values, while reducing experimental procedures. Accurate heat values ​​can be obtained with simple operations.

[0077] Furthermore, the arc heat generated, i.e., the sixth heat Q6, is calculated using the Gaussian heat source model formula. Since the arc's duration is almost the same as the lightning current's duration, t4 represents the arc's duration. From the model formula given above, the integral formula for calculating the arc heat is: Since the duration of lightning current is short, heat loss can be ignored. That is, the total heat generated to bring the temperature sensing device to the operating temperature under the action of lightning current is: Q3 = Q5 + Q6.

[0078] In the specific implementation process, at least based on the first duration, the fourth heat is determined, including: obtaining the first temperature, second temperature, and third temperature of the pressure plate, wherein the pressure plate has a first surface and a second surface, the first surface is in contact with the component under test, the second surface is in contact with air, the first temperature is the temperature of the first surface, the second temperature is the temperature of the second surface, and the third temperature is the temperature of the air; based on the first duration, the first temperature, the second temperature, and the third temperature, the seventh heat is determined; based on the first heat and the seventh heat, the fourth heat is determined, wherein the fourth heat is the difference between the first heat and the seventh heat.

[0079] In the above embodiments, in the experimental platform, when current passes through the system under test, some heat is consumed by the pressure plate. The heat loss of the pressure plate can be obtained by measuring the internal and external temperatures of the pressure plate, as well as the temperature between the pressure plate and the air, thereby increasing the rationality and accuracy of the experimental platform. Specifically, the first temperature refers to the internal and external temperatures of the pressure plate; the theoretical heat transfer loss can be obtained from the first and second temperatures. The third temperature is the air temperature; the heat convection loss, heat conduction loss, and heat convection loss can be obtained from the second and third temperatures, and can be considered as the heat loss of the pressure plate.

[0080] In the specific implementation process, the seventh heat is determined based on the first temperature, the second temperature, and the third temperature, including: based on the first temperature, the second temperature, and the sixth formula: The first heat loss q1 is obtained, where λ is the thermal conductivity of the pressure plate material, A1 is the area of ​​the contact surface between the pressure plate and the element under test, S is the thickness of the pressure plate, and ΔT1 is the difference between the first and second temperatures. According to the second temperature, the third temperature, and the seventh formula: q2=aA2ΔT2, the second heat loss q2 is obtained, where a is the convective heat transfer coefficient, A2 is the contact area between the pressure plate and the air, and ΔT2 is the difference between the second and third temperatures. According to the first duration and the eighth formula: Q4=(q1+q2)t1, the seventh heat Q4 is obtained, where t1 is the first duration.

[0081] Specifically, analyzing the heat transfer process within the suspension clamp-ground system reveals that when measuring the heat Q generated to bring the device to its operating temperature, it is necessary to consider the heat transfer losses at the contact points between the aluminum sheath and the pressure plate, the contact points between the pressure plate and the sensing core, and the convection losses at the contact points between the pressure plate and the air. The theoretical heat transfer and convection losses are calculated using relevant formulas. The heat conduction loss formula is used as follows: Where q1 is the conductive heat loss per unit time (W), λ is the thermal conductivity of the material (the unit of thermal conductivity is W / (m·K)), A1 is the contact area between the pressure plate and the aluminum strip, ΔT1 is the temperature difference between the upper and lower parts of the pressure plate, and S is the thickness of the pressure plate. Using the heat convection loss formula: q2=aA2ΔT2, where q2 is the convective heat loss per unit time (W), a is the convective heat transfer coefficient (the unit of convective heat transfer coefficient is W / (m2·K)), A2 is the contact area between the pressure plate and the air, and ΔT2 is the temperature difference between the pressure plate and the air. The above two heat loss formulas can yield the total heat loss when the device reaches its designed operating temperature. Based on the actual conditions of the experimental platform, the arc heat generated by the system under test under lightning current can be obtained, further increasing the rationality of the experimental platform and simplifying its operation.

[0082] From these two heat loss formulas, we can obtain the total heat loss when the device reaches the designed operating temperature: Q4=(q1+q2)t1, which gives us the seventh heat Q4, and the fourth heat is the difference between the first heat and the seventh heat.

[0083] In the specific implementation process, based on the third and fourth heat values, the experimental platform is checked to see if it meets the rationality requirements. This includes: determining the relationship between the first difference and the second threshold. The first difference is the absolute value of the difference between the third and fourth heat values. If the first difference is less than the second threshold, the experimental platform meets the rationality requirements.

[0084] Specifically, in the experimental platform, the effects of the combined experimental results under power frequency current and the temperature sensing element are made equivalent. Furthermore, the heat generated by the electric arc is increased by the first heat source, and the heat generated by the pressure plate is subtracted from the third heat source to make the experimental platform meet the conditions for simulating lightning current. In addition, the interference of other components in the system under test on the temperature sensing device is eliminated to increase the accuracy of the experimental platform. Moreover, the difference between the heat generated by the system under test under lightning current and the heat generated by the ground wire-suspension clamp assembly under power frequency current is calculated, and the rationality of the experimental platform is judged by a set second threshold. On the one hand, the rationality error setting of the experimental platform can be adjusted according to the user's needs. On the other hand, when the experimental platform is reasonable, the accuracy of the temperature sensing device is tested, which improves the accuracy of the test results and the user experience.

[0085] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the method for detecting thermal damage to overhead lines of this application will be described in detail below with reference to specific embodiments.

[0086] This embodiment relates to a specific method for detecting thermal damage to overhead power lines, including the following steps:

[0087] Step S11: The lightning current is injected from the lightning strike point, flowing sequentially through the ground wire, aluminum sheath, suspension clamp, fasteners, grounding tower, and finally into the ground. Referring to the SAE (Society of Automotive Engineers) standards for aircraft lightning protection and testing, the standard lightning current waveform has four stages: initial current, intermediate current, continuous DC, and re-impact current. According to research on direct lightning damage to OPGW lines, the main contributing components to the damage to metallic materials caused by lightning strikes are the initial current (A component), which leaves a large number of charge carriers in the metallic material, and the continuous current (C component), which injects a large amount of transferred charge into the metal. Therefore, only the influence of the A and C components on the heating of the ground wire-clamp assembly is considered. Simultaneously, local breakdown occurs near the ground wire-clamp contact point, resulting in arc discharge. Therefore, the heat generated by the lightning current inside the assembly is partly Joule heating and partly arc heating.

[0088] Step S111: Model and describe the Joule heat source and the arc heat source generated by the high-frequency pulse component and DC component of the lightning current:

[0089] The high-frequency pulse component A is mathematically described using a double exponential function model:

[0090] i A (t)=I P (e -αt -e -βt ),

[0091] In the formula, I pThis represents the amplitude of the A-component of the lightning current. Studies of the lightning current waveform and its expression show that the α and β parameters can be calculated using existing formulas based on the wavefront time and half-peak time of the lightning current. (This calculation method is existing and not an innovation or protection point of this patent.) If the national standard specifies the lightning current wavefront and tail time constant as 1.2 / 50μs (wavefront time / half-peak time), then the values ​​of α and β can be calculated using existing methods to be 1.473×10⁴ and 2.08×10⁶, respectively. The total duration t₃ of the A-component of the lightning current is set. Considering the rapid decay rate of the A-component, t₃ can be set to 500μs, at which point the magnitude of the A-component is approximately 10% of its peak value.

[0092] The DC component C can be directly described mathematically using a square wave, with the current magnitude being I. C The duration of action is t4.

[0093] The generated electric arc heat source is mathematically described using a Gaussian heat source model:

[0094]

[0095] In the formula, I C R(t) represents the DC component of the lightning current, R(t) represents the maximum radius of the Gaussian heat source, and r represents the radius of the electric arc heat source.

[0096] Step S112: Calculate the Joule heat and arc heat generated by the lightning current using the model formulas given above.

[0097] Let R be the total resistance of the lightning current along the path of the ground wire-suspension clamp assembly. 总 The heat generation of the A component of the lightning current was calculated using Joule's law:

[0098]

[0099] And the heat generated by the C component of the lightning current:

[0100]

[0101] The total Joule heat generated is:

[0102] Q5 = Q A +Q C ,

[0103] The arc heat Q6 generated using the Gaussian heat source model formula is calculated as follows: The arc duration is almost the same as the lightning current duration. From the model formula given above, the integral formula for calculating the arc heat is:

[0104]

[0105] Since the duration of lightning current is short, heat loss can be ignored. That is, the total heat generated to bring the temperature sensing device to its operating temperature T under the action of lightning current is:

[0106] Q3 = Q5 + Q6.

[0107] Step S12: Establish an experimental platform with the power frequency current I0 as the excitation and the suspension clamp-ground wire system as the excitation object. The ground wire, the contact resistance of the ground wire and the aluminum sheath, and the aluminum sheath are all incorporated into the current loop.

[0108] The experiment was conducted on this experimental platform, and the time t1 required for the device to reach the designed operating temperature under power frequency current excitation and the time t2 required for the temperature sensing device to activate were measured.

[0109] If we consider the ground wire-suspension clamp assembly as a whole, then the heat generated in this part to bring the device to its designed operating temperature under power frequency current is:

[0110]

[0111] For the temperature sensing device to activate under power frequency current, the heat generated in this part is:

[0112]

[0113] Step S13: Analysis of the heat transfer process within the suspension clamp-ground system reveals that when measuring the heat generated to bring the device to its operating temperature, heat transfer losses at the contact points between the aluminum sheath and the pressure plate, and between the pressure plate and the sensing core, as well as convection losses at the contact points between the pressure plate and the air, need to be considered. The theoretical heat transfer and convection losses are calculated using relevant formulas. The heat conduction loss formula is used as follows:

[0114]

[0115] Where q1 is the amount of heat loss per unit time (W), λ is the thermal conductivity of the material (the unit of thermal conductivity is W / (m·K)), A1 is the area of ​​the contact surface between the pressure plate and the aluminum strip, ΔT1 is the temperature difference between the upper and lower parts of the pressure plate, and S is the thickness of the pressure plate.

[0116] Using the heat convection loss formula:

[0117] q2=aA2ΔT2,

[0118] Where q2 is the convective heat loss per unit time (W), a is the convective heat transfer coefficient (the unit of the convective heat transfer coefficient is W / (m2·K)), A2 is the contact area between the pressure plate and the air, and ΔT2 is the temperature difference between the pressure plate and the air.

[0119] The two heat loss formulas above can be used to obtain the total heat loss when the device reaches its designed operating temperature:

[0120] Q4 = (q1 + q2)t1,

[0121] The seventh heat, Q4, is the total heat lost when the device reaches its designed operating temperature.

[0122] The amount of heat required for the device to reach its designed operating temperature is:

[0123] Q5 = Q1 + Q4,

[0124] Q5 is the fourth type of calorie.

[0125] By comparing and analyzing whether the sizes of Q3 and Q5 are approximately equal within a certain error range, the rationality of the experimental platform design can be verified.

[0126] Step S14: Compare and analyze the two heat values ​​Q1 and Q2 calculated in S2, and calculate the relative error:

[0127]

[0128] This further verifies whether the operating temperature setting of the temperature sensing device is accurate and reliable within a certain error range under this experimental method.

[0129] The above method describes how to obtain some of the parameters in each step.

[0130] Analysis of the heat transfer process within the suspension clamp-ground system reveals that when measuring the heat Q generated to bring the device to its operating temperature, heat transfer losses at the contact points between the aluminum sheath and the pressure plate, and between the pressure plate and the sensing core, as well as convection losses at the contact points between the pressure plate and the air, need to be considered. The theoretical heat transfer and convection losses are calculated using relevant formulas. The heat conduction loss formula is used as follows:

[0131]

[0132] In the formula, 'a' represents the median current, and 'b' is the steepness coefficient, which can be determined based on the lightning activity in the region. When the 'a' and 'b' parameters for a specific region are unavailable, the IEEE recommended values ​​of a = 31 and b = 2.6 can be used. Calculations based on these standard recommended values ​​show that 95% of lightning strike amplitudes are greater than 10 kA, and 50% are greater than 31 kA. Commonly used probabilities and their corresponding lightning current amplitudes are shown in Table 1.

[0133] Table 1

[0134] Lightning current amplitude probability P <![CDATA[The corresponding lightning current amplitude I P (kA)]]> 0.99 5.29 0.95 10 0.5 31 0.1 72.2 0.05 96.2 0.01 181.5 0.005 237.4

[0135] The DC component C can be selected based on the parameters of different levels in the aircraft lightning protection standards issued by SAE (Society of Automotive Engineers). Here, we take the peak current I. CThe current is 100A, the action time t4 is 500ms, and the parameters of the C component (continuous current) of the lightning current are shown in Table 2.

[0136] Table 2

[0137]

[0138] In relevant studies, the radius r of the arc heat source is usually taken in the range of 2.5 to 15 mm. However, for the arc discharge caused by lightning strikes on overhead lines near the clamp assembly, it is considered to be a discharge inside a tiny gap, and the radius of the arc heat source is taken as 5 mm.

[0139] resistor R 总 The value can be obtained through a black-box experiment, which treats the components corresponding to the resistor as a whole, applies an external excitation, measures the response, and then calculates the corresponding value. Existing impedance measuring instruments and the bridge method for measuring resistance can be used to perform this black-box experiment.

[0140] The area A1 of the contact surface between the pressure plate and the aluminum strip can be obtained using the elliptical cylindrical conductive bridge model, and its calculation formula is as follows:

[0141]

[0142] Where n is the number of bolts to which torque is applied (here n = 4); T C d is the bolt torque (taken as above 10 N·m when the bolt is tightened, and below 1 N·m when the bolt is loose); K is the thread friction coefficient, usually taken as 0.2; b ζ is the nominal diameter of the bolt; ζ is a coefficient characterizing the contact condition, ranging from 0.3 to 0.6, and is usually taken as 0.45 in engineering calculations; H is the Brinell hardness of the contact interface material, which is obtained by measuring it using a digital Brinell hardness tester.

[0143] The contact area A2 between the pressure plate and the air does not need to consider the bottom surface of the pressure plate that is in close contact with the ground wire of the wrapped aluminum tape. That is, the actual contact area is the upper surface and side surface of the pressure plate, and the specific value can be calculated by measuring the actual size of the pressure plate.

[0144] The experimental procedure of the experimental platform may include the following steps:

[0145] Step S21: Check the paperless recorder and thermocouple settings;

[0146] Step S22: Check the electrical connections;

[0147] Step S23: Connect the main power supply, adjust the control circuit of the high current generator, and at the same time use a clamp meter to obtain the current value at the output terminal of the step-down transformer.

[0148] Step S24: When the current reaches the required value, quickly turn off the main power switch, keep the voltage regulator lever position unchanged, and obtain the current value I0.

[0149] Step S5: Observe the temperature of the overhead ground wire-suspension clamp assembly using a thermocouple temperature measuring device until the overall temperature drops to room temperature ±5%.

[0150] Step S6: Turn on the main power switch to apply the set current value to the sample instantaneously and start timing;

[0151] Step S7: Obtain thermocouple values ​​until the device reaches the designed operating temperature, then disconnect the power supply to the generating circuit and obtain the duration.

[0152] Step S8: Repeat steps S4, S5 and S6 to obtain the duration multiple times and determine the average value, which is t1.

[0153] Step S9: Repeat steps S4 and S5, continuously acquiring thermocouple values ​​until the device's activation timing ends, then disconnect the power supply to the generating circuit and acquire the duration.

[0154] Step S10: Repeat step 8 to obtain the duration multiple times and determine the average value, which is denoted as t2.

[0155] Alternatives to the aforementioned methods include lightning strike experiments, finite element simulation experiments, and constant temperature chamber experiments. One method involves directly exciting the sample on the experimental platform with lightning current; however, existing excitation devices cannot fully simulate lightning current, and the enormous energy of lightning current poses significant safety hazards. Another method is to use finite element simulation, but this method cannot completely simulate actual conditions, requires quantification of experimental platform parameters, resulting in complex data and a large computational load. Platform construction is also difficult, with poor adjustability of structural parameters, boundary conditions, and excitation settings, requiring substantial time and effort. A third method is to use a constant temperature chamber, but the physical processes within the chamber differ significantly from those during an actual lightning strike, leading to substantial errors compared to the short-duration high-temperature conditions of a lightning strike. This experimental method uses a high-current generator as a constant current excitation source and constructs an experimental platform based on a real-world application scenario, offering significant advantages over the alternatives.

[0156] According to another aspect of this application, a device for detecting thermal damage to overhead lines is provided, such as... Figure 8 As shown, it includes:

[0157] The first acquisition unit 10 is used to acquire the resistance of the system under test. The experimental platform includes the system under test and the excitation module connected to it. The system under test includes a temperature sensing device, a test element and a pressure plate. The pressure plate is connected to the temperature sensing device and the test element.

[0158] Control unit 20 is used to control the excitation module to apply power frequency current to the system under test in order to obtain the first duration for the temperature of the system under test to reach the preset temperature and the second duration for the temperature sensing device to activate.

[0159] The determining unit 30 is used to determine, at least based on the resistance, a first heat and a second heat, wherein the first heat is the heat generated when the temperature of the system under test reaches a preset temperature, and the second heat is the heat generated by the system under test when the temperature sensing device is activated;

[0160] The judgment unit 40 is used to determine whether the operation of the temperature sensing device is accurate based on the first heat and the second heat.

[0161] The detection unit 50 is used to detect thermal damage to overhead lines using a temperature sensing device, provided that the operation of the temperature sensing device meets the accuracy requirements.

[0162] This embodiment overcomes the shortcomings of existing experimental methods for testing thermal damage to overhead lines in power grid systems by verifying the accuracy and reliability of the temperature sensing device's operation through a constructed experimental platform. The experimental platform includes a system under test (SUT) and an excitation module. The SUT includes a temperature sensing device, a test element, and a pressure plate. The pressure plate connects the temperature sensing device and the test element. A first acquisition unit acquires the resistance of the SUT to increase detection accuracy. A control unit controls the excitation module to apply a power frequency current to the SUT to acquire the first duration for the SUT to reach a preset temperature and the second duration for the temperature sensing device to activate. Using the power frequency current as the excitation current can equivalently represent the physical process of lightning current, as its current path is the same as that of lightning current, and it can equivalently represent the heat generated at the sensing part during the lightning current's action, avoiding the problems caused by artificial lightning strikes. The high cost and stringent conditions reduce the risks associated with manual heat diversion. The determination unit is used to determine, at least based on resistance, the first heat and the second heat. The first heat is the heat generated when the temperature of the system under test reaches a preset temperature, and the second heat is the heat generated when the temperature sensing device activates. The judgment unit is used to determine whether the activation of the temperature sensing device meets the accuracy requirements based on the first and second heats. Using power frequency current as the current excitation, the heat generated when the device reaches its activation temperature and the heat generated when the device activates are compared and analyzed to verify the accuracy of the core temperature sensing element's activation temperature design. The detection unit is used to detect thermal damage to overhead lines using the temperature sensing device, provided that the activation of the temperature sensing device meets the accuracy requirements. Using a temperature sensing device that meets the accuracy requirements to detect thermal damage and defects in overhead lines simplifies the detection method and increases the accuracy of the detection. The above method, using power frequency current as the excitation, is a heat equivalent experimental method that can equivalently represent the physical process of lightning current. Its current path is the same as the lightning current path, and it can equivalently represent the heat generated at the sensing part during the lightning current's action. At the same time, this experimental method also has the advantages of low cost, convenient operation, and high safety factor.

[0163] In the specific implementation process, the aforementioned determining unit includes a first calculation unit and a second calculation unit, wherein the first calculation unit is used to determine the resistance and a first formula: The first heat Q1 is obtained, where I0 is the power frequency current and R... 总 The first unit is the resistance, and t1 is the first time duration; the second calculation unit is used to calculate based on the resistance and the second formula: The second heat, Q2, is obtained, where t2 is the second duration. According to Joule's law, the corresponding heat can be obtained simply by acquiring the experimental time. During the experiment, the duration is relatively easy to obtain, and the heat obtained for the duration is also relatively accurate, reducing the operational difficulty of the experimental platform, improving its accuracy, and simultaneously reducing its cost.

[0164] In the specific implementation process, the judgment unit includes a third calculation unit, a first judgment subunit, and a first determination subunit. The third calculation unit is used to determine the first calorific value, the second calorific value, and the third formula. The relative error σ is obtained; the first judgment subunit is used to determine the relationship between the relative error σ and the first threshold; the first determination subunit is used to ensure that the operation of the temperature sensing device meets the accuracy requirements when the relative error σ is less than the first threshold. Using power frequency current as the current excitation, the heat generated when the device reaches its operating temperature and the heat generated when the device activates are compared and analyzed to verify the accuracy of the operating temperature design of the core temperature sensing element. By setting the first threshold to determine whether the operation of the temperature sensing device meets the accuracy requirements, the experimental difficulty is reduced. Furthermore, the error setting can be adjusted according to user needs, improving the user experience while accurately and reliably determining whether the operating temperature setting of the temperature sensing device meets the requirements.

[0165] In its specific implementation, the aforementioned detection device package further includes: a first determining unit, a second determining unit, and a first detection subunit. The first determining unit is used to determine a third heat source based at least on the resistance; this third heat source is the heat generated by the temperature sensing device in the system under test when a lightning current passes through it. The second determining unit is used to determine a fourth heat source based at least on a first duration; this fourth heat source is the heat generated by the temperature sensing device in the system under test when a power frequency current passes through it. The first detection subunit verifies whether the experimental platform meets the rationality requirements based on the third and fourth heat sources. This can further enhance the accuracy of the experimental platform's judgment on the temperature sensing device. If the experimental platform does not meet the rationality requirements, further adjustments can be made to obtain a reasonable power frequency current.

[0166] In the specific implementation process, the aforementioned first determining unit includes a second determining subunit, a third determining subunit, and a fourth determining subunit. The second determining subunit is used to determine the fifth heat source based on resistance and Joule's law, where the fifth heat source is the heat generated by the lightning current flowing through the system under test. The third determining subunit is used to determine the sixth heat source based on resistance and a Gaussian heat source model, where the sixth heat source is the heat generated by a partial breakdown of the system under test. The fourth determining subunit is used to determine the third heat source based on the fifth and sixth heat sources, where the third heat source is the sum of the fifth and sixth heat sources. This simplifies the experimental procedure while ensuring experimental accuracy.

[0167] In the specific implementation process, the second determining subunit includes a third calculation unit, a fourth calculation unit, and a fifth determining subunit. The third determining subunit is used to determine the resistance and the fourth formula: The heat Q generated by the first conductive current is obtained A , among which, I p R is the amplitude of the initial current. 总Let be the resistance, α be the wavefront time of the lightning current, β be the half-peak time of the lightning current, t be the duration of the leading current, and t3 be the total duration of the leading current. The lightning current includes both the leading current and the continuous current. The fourth calculation unit is used to calculate the resistance based on the fifth formula: The heat Q generated by the continuous current is obtained C , among which, I C For continuous current, t4 is the total duration of the continuous current; the fifth determining subunit is used to determine the heat Q. A And calories Q C The fifth calorie is obtained, where the fifth calorie is calorie Q. A And calories Q C The sum of the two. By obtaining the heat generated by the initial conductive current A and the continuous current C, the heat generated by the lightning current flowing through the system under test can be obtained. This allows for a scientific determination of the heat generated by the lightning current flowing through the system under test, resulting in more accurate heat values. At the same time, it reduces the experimental operation, allowing for accurate heat values ​​to be obtained in a simple operation.

[0168] In the specific implementation process, the second determining unit includes a first acquisition subunit, a sixth determining subunit, and a seventh determining subunit. The first acquisition subunit acquires the first, second, and third temperatures of the pressure plate. The pressure plate has a first surface and a second surface; the first surface contacts the element under test, and the second surface contacts the air. The first temperature is the temperature of the first surface, the second temperature is the temperature of the second surface, and the third temperature is the air temperature. The sixth determining subunit determines a seventh heat based on the first duration, the first temperature, the second temperature, and the third temperature. The seventh determining subunit determines a fourth heat based on the first heat and the seventh heat, where the fourth heat is the difference between the first heat and the seventh heat. This increases the rationality and accuracy of the experimental platform.

[0169] In the specific implementation process, the sixth determining subunit includes a fifth calculation unit, a sixth calculation unit, and a seventh calculation unit. The fifth calculation unit is used to determine the first temperature, the second temperature, and the sixth formula: The first heat loss q1 is obtained, where λ is the thermal conductivity of the pressure plate material, A1 is the contact area between the pressure plate and the component under test, S is the thickness of the pressure plate, and ΔT1 is the difference between the first and second temperatures. The sixth calculation unit is used to obtain the second heat loss q2 based on the second and third temperatures and the seventh formula: q2=aA2ΔT2, where a is the convective heat transfer coefficient, A2 is the contact area between the pressure plate and the air, and ΔT2 is the difference between the second and third temperatures. The seventh calculation unit is used to obtain the seventh heat Q4 based on the first duration and the eighth formula: Q4=(q1+q2)t1, where t1 is the first duration. The arc heat generated by the system under test under lightning current can be obtained according to the actual situation of the experimental platform, further increasing the rationality of the experimental platform and simplifying its operation.

[0170] In specific implementation, the first detection subunit includes a second judgment subunit and an eighth determination subunit. The second judgment subunit determines the relationship between a first difference and a second threshold, where the first difference is the absolute value of the difference between the third and fourth heat values. The eighth determination subunit is used to ensure the experimental platform meets the rationality requirements when the first difference is less than the second threshold. This allows for adjustment of the experimental platform's rationality error setting according to user needs. Furthermore, when the experimental platform is rational, it enables accuracy testing of the temperature sensing device, improving both the accuracy of the detection results and the user experience.

[0171] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0172] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0173] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0174] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0175] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0176] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0177] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0178] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0179] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0180] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0181] 1) The method for detecting thermal damage to overhead lines in this application overcomes the shortcomings of existing experimental methods for detecting thermal damage to overhead lines in power grid systems by constructing an experimental platform to verify the accuracy and reliability of the temperature sensing device. The experimental platform includes a system under test (SUT) and an excitation module. The SUT includes a temperature sensing device, a test element, and a pressure plate. The pressure plate connects the temperature sensing device and the test element to obtain the resistance of the SUT, increasing the accuracy of the detection. The excitation module applies a power frequency current to the SUT to obtain the first duration for the SUT to reach a preset temperature and the second duration for the temperature sensing device to activate. Using the power frequency current as the excitation current, the physical process of lightning current can be equivalently represented, as its current path is the same as that of lightning current, and it can equivalently represent the heat generated at the sensing part during the lightning current's action, avoiding the need for artificial lightning strikes. The method leads to high costs and stringent conditions, reducing the dangers of manual diversion. At least based on resistance, the first and second heat sources are determined. The first heat source is the heat generated when the temperature of the system under test reaches the preset temperature, and the second heat source is the heat generated when the temperature sensing device activates. Based on the first and second heat sources, it is determined whether the activation of the temperature sensing device meets the accuracy requirements. Using power frequency current as the current excitation, the heat generated when the device reaches the activation temperature and the heat generated when the device activates are compared and analyzed to verify the accuracy of the core temperature sensing element's activation temperature design. When the activation of the temperature sensing device meets the accuracy requirements, the temperature sensing device is used to detect thermal damage to overhead lines. Using a temperature sensing device that meets the accuracy requirements to detect thermal damage and thermal defects in overhead lines simplifies the detection method and increases the accuracy of the detection. The above method, using power frequency current as the excitation, is a heat equivalent experimental method that can equivalently represent the physical process of lightning current. Its current path is the same as the lightning current path, and it can equivalently represent the heat generated at the sensing part during the lightning current's action. At the same time, this experimental method also has the advantages of low cost, convenient operation, and high safety factor.

[0182] 2) The overhead line thermal damage detection device of this application, through this embodiment, overcomes the shortcomings of existing experimental methods for testing overhead line thermal damage in power grid systems by verifying the accuracy and reliability of the temperature sensing device's operation through a constructed experimental platform. The experimental platform includes a system under test (SUT) and an excitation module. The SUT includes a temperature sensing device, a test element, and a pressure plate. The pressure plate connects the temperature sensing device and the test element. A first acquisition unit is used to acquire the resistance of the SUT to increase the accuracy of the detection. A control unit is used to control the excitation module to apply a power frequency current to the SUT to acquire the first duration for the SUT's temperature to reach a preset temperature and the second duration for the temperature sensing device to activate. By using the power frequency current as the excitation current, the physical process of lightning current can be equivalently represented, as its current path is the same as that of lightning current, and it can also be equivalent to the heat generated at the sensing part during the lightning current's action. To avoid the high costs and stringent conditions associated with manual lightning strikes and reduce the risks associated with such methods, the following steps are taken: A determination unit is used to determine, based at least on resistance, the first and second heat sources. The first heat source is the heat generated when the system under test reaches a preset temperature, and the second heat source is the heat generated when the temperature-sensing device activates. A judgment unit is used to determine whether the activation of the temperature-sensing device meets accuracy requirements based on the first and second heat sources. Using power frequency current as the excitation, the heat generated when the device reaches its activation temperature is compared with the heat generated when the device activates, verifying the accuracy of the core temperature-sensing element's activation temperature design. A detection unit is used to detect thermal damage to overhead lines using the temperature-sensing device, provided the device's activation meets accuracy requirements. Using a temperature-sensing device that meets accuracy requirements simplifies the detection method and increases its accuracy. This method, using power frequency current as the excitation, provides an equivalent heat experiment that can represent the physical process of lightning current, with the current path being the same as the lightning current path, and can represent the heat generated at the sensing part during the lightning current's action. Furthermore, this experimental method offers advantages such as low cost, ease of operation, and high safety.

[0183] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting thermal damage to overhead power lines, characterized in that, include: The resistance of the system under test is obtained. The experimental platform includes the system under test and the excitation module connected together. The system under test includes a temperature sensing device, a test element and a pressure plate. The pressure plate is connected to the temperature sensing device and the test element. The excitation module is controlled to apply a power frequency current to the system under test in order to obtain the first duration for the temperature of the system under test to reach a preset temperature and the second duration for the temperature sensing device to activate. At least based on the resistance, a first heat and a second heat are determined, wherein the first heat is the heat generated when the temperature of the system under test reaches the preset temperature, and the second heat is the heat generated by the system under test when the temperature sensing device is activated; Based on the first heat and the second heat, determine whether the operation of the temperature sensing device meets the accuracy requirements; Provided that the temperature sensing device meets the accuracy requirements, the temperature sensing device is used to detect thermal damage to the overhead line. Determining whether the operation of the temperature sensing device meets the accuracy requirement based on the first heat and the second heat includes: based on the first heat, the second heat, and a third formula: To obtain the relative error Determine the relative error The relationship between the magnitude of the first threshold and the relative error; When the temperature is less than the first threshold, the operation of the temperature sensing device meets the accuracy requirement. The method further includes: determining a third heat source based at least on the resistance, the third heat source being the heat generated by the temperature sensing device under the condition of passing a lightning current; determining a fourth heat source based at least on the first duration, the fourth heat source being the heat generated by the temperature sensing device under the condition of passing a power frequency current; and verifying whether the experimental platform meets the rationality requirements based on the third heat source and the fourth heat source.

2. The detection method according to claim 1, characterized in that, Determining the first heat and the second heat, at least based on the resistance, includes: Based on the aforementioned resistance and the first formula: The first heat was obtained. ,in, The power frequency current, For the resistor, This is the first duration; According to the aforementioned resistance and the second formula: The second heat is obtained. ,in, This is the second duration.

3. The detection method according to claim 1, characterized in that, Determining the third heat source based at least on the resistance includes: Based on the resistance and Joule's law, the fifth heat is determined, wherein the fifth heat is the heat generated by the lightning current flowing through the system under test; Based on the resistance and Gaussian heat source model, the sixth heat source is determined, wherein the sixth heat source is the heat generated by the partial breakdown of the system under test; The third heat is determined based on the fifth heat and the sixth heat, wherein the third heat is the sum of the fifth heat and the sixth heat.

4. The detection method according to claim 3, characterized in that, Determining the fifth heat source based on the aforementioned resistance and Joule's law includes: Based on the aforementioned resistance and the fourth formula: The heat generated by the first electric current is obtained. ,in, The magnitude of the leading current. For the resistor, Let be the wavefront time of the lightning current. The half-peak time of the lightning current. The duration of the initial conductive current. The total duration of the preceding conductive current, wherein the lightning current includes the preceding conductive current and the continuous current; Based on the aforementioned resistance and the fifth formula: The heat generated by the continuous current is obtained. ,in, For the continuous current, The total duration of the continuous current; According to the heat and the heat The fifth heat is obtained, wherein the fifth heat is the heat. and the heat sum.

5. The detection method according to claim 1, characterized in that, Determining the fourth heat amount based at least on the first duration includes: The first temperature, second temperature, and third temperature of the pressure plate are obtained, wherein the pressure plate has a first surface and a second surface, the first surface is in contact with the element under test, the second surface is in contact with air, the first temperature is the temperature of the first surface, the second temperature is the temperature of the second surface, and the third temperature is the temperature of the air. The seventh heat is determined based on the first duration, the first temperature, the second temperature, and the third temperature; The fourth heat is determined based on the first heat and the seventh heat, wherein the fourth heat is the difference between the first heat and the seventh heat.

6. The detection method according to claim 5, characterized in that, Determining the seventh heat based on the first temperature, the second temperature, and the third temperature includes: Based on the first temperature, the second temperature, and the sixth formula: The first heat loss was obtained. ,in, The thermal conductivity of the material of the pressure plate is given. The area of ​​the contact surface between the pressure plate and the component under test. The thickness of the pressure plate is [missing information]. The difference between the first temperature and the second temperature; Based on the second temperature, the third temperature, and the seventh formula: The second heat loss was obtained. ,in, The convective heat transfer coefficient is... The contact area between the pressure plate and the air. The difference between the second temperature and the third temperature; Based on the first duration and the eighth formula: The seventh heat is obtained. ,in, This is the first duration.

7. The detection method according to claim 1, characterized in that, Based on the third and fourth heat sources, verify whether the experimental platform meets the rationality requirements, including: Determine the relationship between the first difference and the second threshold, where the first difference is the absolute value of the difference between the third heat and the fourth heat. If the first difference is less than the second threshold, the experimental platform meets the rationality requirement.

8. A device for detecting thermal damage to overhead power lines, characterized in that, include: The first acquisition unit is used to acquire the resistance of the system under test. The experimental platform includes the system under test and the excitation module connected together. The system under test includes a temperature sensing device, a test element and a pressure plate. The pressure plate is connected to the temperature sensing device and the test element. The control unit is used to control the excitation module to apply a power frequency current to the system under test in order to obtain the first duration for the temperature of the system under test to reach a preset temperature and the second duration for the temperature sensing device to activate. The determining unit is configured to determine, at least based on the resistance, a first heat and a second heat, wherein the first heat is the heat generated when the temperature of the system under test reaches the preset temperature, and the second heat is the heat generated by the system under test when the temperature sensing device is activated; The judgment unit is used to determine whether the operation of the temperature sensing device meets the accuracy requirements based on the first heat and the second heat. The detection unit is used to detect thermal damage to the overhead line using the temperature sensing device, provided that the operation of the temperature sensing device meets the accuracy requirements. The judgment unit includes a third calculation unit, a first judgment subunit, and a first determination subunit, wherein the third calculation unit is used to determine the first heat, the second heat, and a third formula: The relative error is obtained. The first judgment subunit is used to judge the relative error. The relationship between the magnitude of the first threshold and the relative error; the first determining subunit is used to determine the relative error. When the temperature is less than the first threshold, the operation of the temperature sensing device meets the accuracy requirement. The detection device package further includes: a first determining unit, a second determining unit, and a first detection subunit, wherein the first determining unit is used to determine a third heat source based at least on the resistance, the third heat source being the heat generated by the temperature sensing device under the condition of passing a lightning current; the second determining unit is used to determine a fourth heat source based at least on the first duration, the fourth heat source being the heat generated by the temperature sensing device under the condition of passing a power frequency current; and the first detection subunit is used to verify whether the experimental platform meets the rationality requirements based on the third heat source and the fourth heat source.

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