A transformer bushing pile head heating defect cause identification method and system and medium

Abstract

The application discloses a transformer bushing pile head heating defect reason identification method and system and a medium, and the method comprises the following steps: acquiring an infrared thermal imaging spectrum of a transformer bushing pile head; determining a temperature distribution type set contained by the transformer bushing pile head according to the infrared thermal imaging spectrum; determining a heating defect type of the transformer bushing pile head according to a correspondence relationship between the temperature distribution type set and the heating defect type which is determined in advance; in addition, three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation is further performed to determine the correspondence relationship between the temperature distribution type set and the heating defect type. Through the correspondence relationship between the temperature distribution type set and the heating defect type which is determined in advance, the temperature distribution type set contained by the transformer bushing pile head can be determined in combination with the infrared thermal imaging spectrum, and the accurate identification of the heating defect type of the transformer bushing pile head can be realized.

Description

Technical Field

[0001] This invention belongs to the field of power transformer operation and maintenance technology, specifically relating to a method, system and medium for identifying the causes of thermal defects in transformer bushing terminals. Background Technology

[0002] With the rapid development of my country's economy, the demand for electricity is constantly increasing. Ensuring the safe and stable operation of substation equipment is a crucial link in ensuring a high-quality and reliable power supply. The transformer is the most critical primary equipment in a substation, serving as the hub and heart of the power grid. A transformer defect or malfunction can lead to widespread power outages, affecting the reliable supply of electricity. During peak load periods, overheating defects at the bushing terminals of transformers frequently occur. Prolonged overheating of the terminals leads to oxidation and even corrosion of the current-carrying metal, increasing the contact resistance between the terminal and the clamp, further exacerbating localized current concentration, and ultimately creating a vicious cycle of deteriorating current-carrying capacity and accelerating temperature rise. When the local temperature rise of the terminal exceeds the melting point of the current-carrying metal, the disconnection between the terminal and the clamp will directly cause the transformer to trip and the entire substation to lose power. Currently, substation maintenance personnel use infrared thermometers to monitor the temperature of the bushing terminals, which can only identify the hottest part of the terminal through infrared thermal imaging, but cannot accurately determine the cause of the overheating defect and carry out targeted repairs. In summary, the current method for identifying the causes of thermal defects at pile heads relies on the experience of maintenance personnel and is limited by the accuracy of infrared thermal imaging spectra. It lacks a logically clear and criterion-based method for identifying thermal defects at pile heads. Summary of the Invention

[0003] The technical problem to be solved by the present invention is as follows: In view of the above-mentioned problems in the prior art, the present invention provides a method, system and medium for identifying the causes of thermal defects in transformer bushing piles. The present invention determines the set of temperature distribution types contained in the transformer bushing pile head by combining the correspondence between a pre-determined set of temperature distribution types and the types of thermal defects with infrared thermal imaging spectra. This can achieve accurate identification of the types of thermal defects in transformer bushing pile heads and has the advantages of clear logic and clear criteria.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for identifying the causes of thermal defects in transformer bushing posts includes:

[0006] S101, Obtain the infrared thermal imaging spectrum of the transformer bushing pile head;

[0007] S102, Determine the set of temperature distribution types contained in the transformer bushing head based on the infrared thermal imaging spectrum;

[0008] S103, Based on the correspondence between the pre-determined set of temperature distribution types and the types of heating defects, determine the type of heating defect of the transformer bushing head.

[0009] Optionally, the temperature distribution type set in step S102 may include the following temperature distribution types: Type A: Temperature concentration at the nut / screw, and the difference between the peak value and the calibrated value exceeds the first peak value setting; Type B: Temperature difference between the thread / hole contact surface and the calibrated value exceeds the first temperature setting value; Type C: Local temperature rise in the thread, and the difference between the peak value and the calibrated value exceeds the second peak value setting value, where the second peak value setting value is larger than the first peak value setting value; Type D: Temperature concentration area on the pile head surface is distributed in a spot-like pattern; Type E: Temperature rise on the pile head surface is uniform, and the difference between the peak value and the calibrated value exceeds the first peak value setting value; Type F: Temperature difference between a local area of ​​the pile head and the ambient temperature is less than the second temperature setting value.

[0010] Optionally, the types of heat-generating defects in step S103 include six types: loose contact between the bolt and the pile head, bolt axis misalignment, thread rust or corrosion, uneven contact surface of the pile head, ablation or corrosion of the contact surface of the pile head, and misalignment of the contact surface of the pile head.

[0011] Optionally, before step S103, a three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation is performed to determine the correspondence between the set of temperature distribution types and the types of heat-generating defects. The three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation includes:

[0012] S201, A three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the transformer bushing pile head is established. The three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the pile head includes a three-dimensional model, an electromagnetic model, and a thermal model of the transformer bushing pile head.

[0013] S202, for the three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation model, simulates each type of heat-generating defect to obtain the temperature distribution type corresponding to the heat-generating defect type, and finally obtains the correspondence between the set of temperature distribution types and the heat-generating defect type.

[0014] Optionally, in the three-dimensional model of the transformer bushing pile head established in step S201, the average height σ of the contact surface between the three-dimensional model and the electromagnetic model through the transformer bushing pile head is... asp With average slope m asp To couple.

[0015] Optionally, the average height σ of the contact surface of the transformer bushing pile head asp With average slope m asp The expression for the computation function is:

[0016]

[0017] In the above formula, σ asp,u With σ asp,d These are the average heights of the protrusions on the upper and lower sides of the contact surface, respectively; m asp,u With m asp,d These are the average slopes of the upper and lower surfaces of the contact surface, respectively.

[0018] Optionally, the functional expression of the electromagnetic model established in step S201 is:

[0019]

[0020] In the above formula, σ contact Let σ be the conductivity of the contact surface. u With σ d These are the electrical conductivity of the materials on both sides of the contact surface, σ asp The average height of the contact surface, m asp denoted as the average slope of the contact surface, p as the contact pressure, and Hc as the hardness of the softer material; p is the contact pressure.

[0021] Optionally, the functional expression of the thermal model established in step S201 is:

[0022] q = h·(T) w -T f ),

[0023] In the above formula, q is the heat flux density, h is the heat transfer coefficient, and T is the heat transfer temperature. w and T f These are the pile head temperature and the ambient air temperature, respectively.

[0024] In addition, the present invention also provides a transformer bushing post heating defect cause identification system, including a microprocessor and a memory interconnected, wherein the microprocessor is programmed or configured to execute the transformer bushing post heating defect cause identification method.

[0025] Furthermore, the present invention also provides a computer-readable storage medium storing a computer program, the computer program being programmed or configured by a microprocessor to execute the method for identifying the cause of thermal defects in transformer bushing piles.

[0026] Compared with existing technologies, the present invention has the following main advantages: The method of the present invention includes acquiring an infrared thermal imaging spectrum of the transformer bushing head; determining the set of temperature distribution types contained in the transformer bushing head based on the infrared thermal imaging spectrum; determining the type of heating defect in the transformer bushing head based on the correspondence between the pre-determined set of temperature distribution types and the type of heating defect; and further includes performing a three-dimensional force-electromagnetic-thermal coupling temperature rise simulation of the head to determine the correspondence between the set of temperature distribution types and the type of heating defect. The present invention, by determining the set of temperature distribution types contained in the transformer bushing head through the pre-determined correspondence between the set of temperature distribution types and the type of heating defect, combined with the infrared thermal imaging spectrum, can achieve accurate identification of the type of heating defect in the transformer bushing head, and has the advantages of clear logic and explicit criteria. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the basic process of the method in an embodiment of the present invention.

[0028] Figure 2 A three-dimensional model of the transformer bushing pile head established for embodiments of the present invention.

[0029] Figure 3 This is a schematic diagram of the microscopic cross-sectional structure of the pile head contact surface in an embodiment of the present invention. Detailed Implementation

[0030] like Figure 1 As shown, the method for identifying the cause of thermal defects in transformer bushing posts in this embodiment includes:

[0031] S101, Obtain the infrared thermal imaging spectrum of the transformer bushing pile head;

[0032] S102, Determine the set of temperature distribution types contained in the transformer bushing head based on the infrared thermal imaging spectrum;

[0033] S103, Based on the correspondence between the pre-determined set of temperature distribution types and the types of heating defects, determine the type of heating defect of the transformer bushing head.

[0034] In this embodiment, the temperature distribution types that can be included in the temperature distribution type set in step S102 include: Type A: Temperature concentration at the nut and bolt, and the difference between the peak value and the calibrated value exceeds the first peak value setting; Type B: Temperature difference between the thread and bolt hole contact surface and the calibrated value exceeds the first temperature setting value; Type C: Local temperature rise of the thread, and the difference between the peak value and the calibrated value exceeds the second peak value setting value, where the second peak value setting value is larger than the first peak value setting value; Type D: Temperature concentration area on the pile head surface is distributed in a spot-like pattern; Type E: Temperature rise of the pile head surface is uniform, and the difference between the peak value and the calibrated value exceeds the first peak value setting value; Type F: Temperature difference between a local area of ​​the pile head and the ambient temperature is less than the second temperature setting value.

[0035] In this embodiment, the types of heat-generating defects in step S103 include six types: loose contact between the bolt and the pile head, bolt axis misalignment, thread rust or corrosion, uneven contact surface of the pile head, ablation or corrosion of the contact surface of the pile head, and misalignment of the contact surface of the pile head.

[0036] In this embodiment, before step S103, a three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation is performed to determine the correspondence between the set of temperature distribution types and the types of heat-generating defects. The three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation includes:

[0037] S201, A three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the transformer bushing pile head is established. The three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the pile head includes a three-dimensional model, an electromagnetic model, and a thermal model of the transformer bushing pile head.

[0038] S202, for the three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation model, simulates each type of heat-generating defect to obtain the temperature distribution type corresponding to the heat-generating defect type, and finally obtains the correspondence between the set of temperature distribution types and the heat-generating defect type.

[0039] In this embodiment, in the three-dimensional model of the transformer bushing pile head established in step S201, the average height σ of the contact surface between the three-dimensional model and the electromagnetic model through the transformer bushing pile head is... asp With average slope m asp To couple.

[0040] In this embodiment, based on the national standards "GB-T 4109-2022 Insulating Bushings for AC Voltages Higher Than 1000V" and "GB / T 5273-2016 Standardization of High Voltage Electrical Terminal Dimensions", the bushing head dimensions for different voltage levels and current magnitudes can be clearly defined. The three-dimensional model of the transformer bushing head is established as follows: Figure 2 As shown, where The diameter of the pile head hole must match the bolt size. 'a' is the longitudinal distance between the two holes, 'd' is the transverse distance between the two holes, and 'h' is the pile head thickness.

[0041] The contact pressure distribution at the pile head interface is uneven, and the actual contact state of the pile head differs significantly from the ideal contact state. Under a microscopic structure, the pile head contact surface is as follows: Figure 3 As shown. In this embodiment, the average height σ of the contact surface of the transformer bushing pile head is... asp With average slope m asp The expression for the computation function is:

[0042]

[0043] In the above formula, σ asp,u With σ asp,d These are the average heights of the protrusions on the upper and lower sides of the contact surface, respectively; m asp,u With m asp,d These are the average slopes of the upper and lower surfaces of the contact surface, respectively.

[0044] Assuming the rough surface is isotropic and the contact surface undergoes plastic deformation, the electrical conductivity of the contact surface can be calculated using the Cooper-Mikic-Yovanovich (CMY) relationship. The functional expression of the electromagnetic model established in step S201 of this embodiment is as follows:

[0045]

[0046] In the above formula, σ contact Let σ be the conductivity of the contact surface. u With σ d These are the electrical conductivity of the materials on both sides of the contact surface, σ asp The average height of the contact surface, m asp Let p be the average slope of the contact surface, p be the contact pressure, and Hc be the hardness of the softer material; p is the contact pressure. Contact conductivity is related to the electromagnetic, mechanical, and microscopic contact parameters of the pivot material. Among these, contact pressure is the most important factor affecting contact conductivity.

[0047] The casing pile head is exposed to outdoor air. Convective heat transfer driven by the temperature gradient between the pile head and the air is the primary form of heat dissipation. To simplify the model, only the heat dissipation of the pile head under natural convection is considered, ignoring forced convection caused by meteorological factors. In this embodiment, the functional expression of the thermal model established in step S201 is:

[0048] q = h·(T) w -T f ),

[0049] In the above formula, q is the heat flux density under natural convection (heat exchange between the pile head surface and the air per unit area and per unit time), h is the heat transfer coefficient (heat transfer per unit time when the temperature difference between the air and the pile head is 1K), and T is the heat transfer coefficient. w and T f The temperatures of the pile head and the surrounding air are respectively represented by the heat transfer coefficient h, which reflects the efficiency of convective heat transfer. Pile head heating is a multi-physics coupling problem involving material mechanics, electromagnetic fields, and solid heat transfer. Contact performance, current-carrying performance, and heat transfer performance are interrelated, making the analysis of pile head heating characteristics technically challenging. Furthermore, the sleeve pile head has a three-dimensional geometric structure, including planar and curved surfaces, and its geometry is also complex due to the need for bolt assembly. In summary, three-dimensional simulation modeling of pile head temperature rise is quite difficult. To analyze the temperature distribution characteristics of heating defects in sleeve pile heads, taking a four-hole planar lap joint as an example, considering the influence of the actual contact state of the pile head on the interface conductivity and the convective heat transfer between the pile head and the air, this embodiment establishes a three-dimensional force-electromagnetic-thermal coupled pile head temperature rise simulation model for transformer sleeve pile heads. This model includes a three-dimensional model, an electromagnetic model, and a thermal model of the transformer sleeve pile head, as well as the average height σ of the contact surface between the three-dimensional model and the electromagnetic model through the transformer sleeve pile head. asp With average slope m asp By coupling these elements, a simple and effective three-dimensional force-electromagnetic-thermal coupled simulation model of pile head temperature rise can be established, ensuring the accuracy of the analysis of pile head thermal characteristics. Simulation based on this three-dimensional force-electromagnetic-thermal coupled model yields a pile head temperature distribution cloud map, quantitatively describing the temperature rise characteristics and qualitatively analyzing the causes of heating defects, achieving practical engineering results.

[0050] In summary, this embodiment proposes a method for identifying the causes of thermal defects in transformer bushing piles based on a three-dimensional force-electromagnetic-thermal coupling simulation model. It examines the temperature rise characteristics of the pile head under different defect conditions, establishes a one-to-one correspondence between defect causes and temperature distribution characteristics, and uses thermal imaging of the pile head to determine its temperature distribution type, thereby clarifying the corresponding cause of the thermal defect, such as loose bolts, uneven contact surfaces, localized ablation, or corrosion. After obtaining the infrared thermal imaging of the bushing pile head, maintenance personnel can categorize the temperature rise type based on the temperature peaks and concentrated temperature areas, and determine the cause of the thermal defect based on the correspondence between the temperature rise type and the cause of the thermal defect. Identifying the causes of thermal defects in pile heads helps to carry out targeted repairs, further improving the efficiency and effectiveness of maintenance. Furthermore, this embodiment does not rely on instruments or equipment, is highly operable, and is easy for substation maintenance personnel to learn and master.

[0051] In addition, this embodiment also provides a transformer bushing post heating defect cause identification system, including a microprocessor and a memory interconnected, the microprocessor being programmed or configured to execute the transformer bushing post heating defect cause identification method.

[0052] In addition, this embodiment also provides a computer-readable storage medium storing a computer program that is programmed or configured by a microprocessor to execute the method for identifying the cause of thermal defects in transformer bushing piles.

[0053] 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-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. 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, create a machine for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The 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 functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus 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.

[0054] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for identifying the causes of thermal defects in transformer bushing posts, characterized in that, include: S101, Obtain the infrared thermal imaging spectrum of the transformer bushing pile head; S102, Determine the set of temperature distribution types contained in the transformer bushing head based on the infrared thermal imaging spectrum; S103, Determine the type of heat-generating defect in the transformer bushing head based on the correspondence between the pre-determined set of temperature distribution types and the types of heat-generating defects; The temperature distribution type set in step S102 includes the following types: Type A: Temperature concentration at the nut / screw point, and the difference between the peak value and the calibrated value exceeds the first peak value setting; Type B: Temperature difference between the thread / hole contact surface and the calibrated value exceeds the first temperature setting value; Type C: Local temperature rise at the thread, and the difference between the peak value and the calibrated value exceeds the second peak value setting value, where the second peak value setting value is larger than the first peak value setting value; Type D: Temperature concentration area on the pile head surface is distributed in a spot-like pattern; Type E: Temperature rise uniformly on the pile head surface, and the difference between the peak value and the calibrated value exceeds the first peak value setting value; Type F: Temperature difference between a local area of ​​the pile head and the ambient temperature is less than the second temperature setting value. The types of heat-generating defects in step S103 include six types: loose contact between bolt and pile head, bolt axis misalignment, thread rust or corrosion, uneven contact surface of pile head, ablation or corrosion of contact surface of pile head, and misalignment of contact surface of pile head. Before step S103, a three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation is performed to determine the correspondence between the set of temperature distribution types and the types of heat-generating defects. This three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation includes: S201, A three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the transformer bushing pile head is established. The three-dimensional force-electromagnetic-thermal coupled simulation model of the temperature rise of the pile head includes a three-dimensional model, an electromagnetic model, and a thermal model of the transformer bushing pile head. S202, for the three-dimensional force-electromagnetic-thermal coupling pile head temperature rise simulation model, simulate each type of heat-generating defect to obtain the temperature distribution type corresponding to the heat-generating defect type, and finally obtain the correspondence between the set of temperature distribution types and the heat-generating defect type; In the three-dimensional model of the transformer bushing pile head established in step S201, the average height σ of the contact surface between the three-dimensional model and the electromagnetic model through the transformer bushing pile head is... asp With average slope m asp To couple.

2. The method for identifying the cause of thermal defects in transformer bushing posts according to claim 1, characterized in that, The average height σ of the contact surface of the transformer bushing pile head asp With average slope m asp The expression for the computation function is: ， In the above formula, and These are the average heights of the protrusions on the upper and lower sides of the contact surface, respectively. and These are the average slopes of the upper and lower surfaces of the contact surface, respectively.

3. The method for identifying the cause of thermal defects in transformer bushing posts according to claim 2, characterized in that, The functional expression of the electromagnetic model established in step S201 is: ， In the above formula, The conductivity of the contact surface, and These are the electrical conductivity of the materials on both sides of the contact surface. The average height of the contact surface. The average slope of the contact surface. To contact pressure, The hardness of a relatively soft material.

4. The method for identifying the cause of thermal defects in transformer bushing posts according to claim 3, characterized in that, The functional expression of the thermal model established in step S201 is: ， In the above formula, For heat flux density, The heat transfer coefficient is... and These are the pile head temperature and the ambient air temperature, respectively.

5. A system for identifying the causes of thermal defects in transformer bushing posts, comprising a microprocessor and a memory interconnected, characterized in that, The microprocessor is programmed or configured to perform the method for identifying the cause of thermal defects in transformer bushing piles as described in any one of claims 1 to 4.

6. A computer-readable storage medium storing a computer program, characterized in that, The computer program is used to be programmed or configured by a microprocessor to execute the method for identifying the cause of thermal defects in transformer bushing piles as described in any one of claims 1 to 4.

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