Cooling capacity-increasing overhead conductor, dynamic current-carrying capacity determination method, medium and equipment

Abstract

The invention provides a cooling capacity-increasing overhead conductor, a dynamic current-carrying capacity determination method, a medium and equipment, and relates to the technical field of power transmission lines, the method is characterized in that the overhead conductor adopts a three-layer composite structure, the outer layer is a passive cooling coating, the thickness is 50-200 [mu] m, the surface is provided with a micro-nano structure for enhancing mid-infrared radiation, the emissivity is greater than or equal to 0.92, and the dynamic current-carrying capacity is greater than or equal to 0.92; the contact angle is greater than 120 degrees through hydrophobic modification treatment; the middle layer is a high-conductivity aluminum alloy conductor layer, and the inner layer is a high-strength galvanized steel core; a directional heat conduction path is formed between the coating and the conductor layer through a gradient heat conduction material, and the heat conductivity coefficient of the gradient material is gradually increased from the coating to the conductor layer; the coating mode of the coating is axial segmented coating or net-shaped coating. According to the overhead conductor, the current-carrying capacity of the line can be effectively improved, the power transmission design of the line is optimized, and the quantitative index of the capacity increasing effect can be obtained through the dynamic current-carrying capacity determination method.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission lines, and particularly relates to a cooling and capacity-increasing overhead conductor, a method for determining dynamic current-carrying capacity, a medium and a device. Background Art

[0002] Traditional overhead conductors are mainly steel-cored aluminum stranded wires (ACSR), and their current-carrying capacity is limited by wire temperature rise and environmental heat dissipation conditions. Existing capacity-increasing methods mostly adopt increasing the conductor cross-sectional area or replacing high-temperature-resistant wires, but there are problems such as high cost and complex construction. The commonly used capacity-increasing schemes in the industry have significant limitations: increasing the conductor cross-sectional area requires replacing the entire section of the wire and upgrading the tower structure accordingly, increasing the engineering cost by 30%-50%; using heat-resistant aluminum alloy wires can raise the operating temperature to 150°C, but the material cost is 2-3 times higher than that of conventional wires, and long-term high-temperature operation will accelerate the oxidation and corrosion of the steel core. Although the passive cooling coating technology can reduce the temperature rise through radiative heat dissipation, there are problems such as uneven coating, unclear influence on mechanical properties, and mismatch of the current-carrying capacity calculation model in the existing coating process. In addition, the synergistic effect between the coating and the conductor and the steel core has not formed a systematic technical solution, lacking a standardized process and a quantitative evaluation method for capacity-increasing effect. Summary of the Invention

[0003] The purpose of the present invention is to provide a cooling and capacity-increasing overhead conductor, a method for determining dynamic current-carrying capacity, a medium and a device, aiming to achieve temperature rise suppression and current-carrying capacity improvement, and establish a supporting current-carrying capacity calculation model and a capacity-increasing effect evaluation method. The specific technical solutions are as follows:

[0004] A cooling and capacity-increasing overhead conductor, the overhead conductor adopts a three-layer composite structure, the outer layer is a passive cooling coating with a thickness of 50-200 μm, the surface has a micro-nano structure for enhancing mid-infrared radiation, the emissivity ≥ 0.92, and it is subjected to hydrophobic modification treatment so that the contact angle > 120°; the middle layer is a high-conductivity aluminum alloy conductor layer, and the inner layer is a high-strength galvanized steel core; a directional heat conduction path is formed between the coating and the conductor layer through a gradient thermal conductivity material, and the thermal conductivity of the gradient material increases from the coating to the conductor layer; the coating method of the coating is axial segmented coating or mesh coating.

[0005] Further, the axial segmented coating method is: periodically arranged coating units are set along the axial direction of the wire, each period includes a coating area with a length of 20 cm and an uncoated area with a length of 10 cm, the coating area is circumferentially fully covered, the uncoated area exposes the conductor layer circumferentially, and the coating period repeats to cover the entire length of the wire.

[0006] Further, the mesh coating method is: a square grid with a side length of 5 mm is formed on the surface of the wire, the grid line width is 1 mm, the coating thickness at the grid intersection is 1.2-1.5 times the thickness of the edge area, and the area ratio of the uncoated area is 76%.

[0007] Furthermore, a flexible transition layer is provided at the interface between the coating layer and the conductor layer, and its elastic modulus is 20%-30% of the coating material.

[0008] Furthermore, the grid intersections of the mesh coating are rounded, and the radius of the rounded corner is ≥0.2 mm.

[0009] The present invention also provides a method for determining the dynamic current-carrying capacity of a cooling and capacity-increasing overhead conductor, including the following steps:

[0010] S100. Geometrically model the overhead conductor;

[0011] S200. Modify the heat conduction model:

[0012] Calculation of non-uniformly coated equivalent emissivity:

[0013] ε eff = η * ε coating +(1 - η) * ε bare

[0014] Among them, ε eff is the equivalent emissivity, ε coating is the emissivity of the coating layer, with a value of 0.92, and ε bare is the emissivity of the bare conductor, with a value of 0.3;

[0015] Calculation of equivalent convective heat transfer coefficient:

[0016] h conv，eff = η * h coating +(1 - η) * h bare

[0017] Among them, h conv，eff is the equivalent convective heat transfer coefficient, h coating is the convective correction coefficient on the coating surface, h bare is the standard convective coefficient of the bare conductor, and h bare = 5.6 + 3.8v, where v represents the wind speed;

[0018] S300. Modify the heat conduction equation:

[0019] The three-dimensional non-uniform heat conduction equation is as follows:

[0020]

[0021] Among them, k(x, y, z) is the spatially distributed thermal conductivity, taking the thermal conductivity of the coating layer in the coated area and the thermal conductivity of the bare conductor in the uncoated area, ρ is the mass density of the object, c p is the specific heat capacity of the object, T is the temperature, and Qjoule is the Joule heat generation rate per unit volume;

[0022] S400. Construct a finite element model:

[0023] Import the 3D CAD model of the wire;

[0024] Create the coating geometric features: For axial segmented coating, use periodic Boolean operations to cut the surface; for mesh coating, generate a mesh by cutting with cross lines;

[0025] Assign material properties to the coating area;

[0026] Define the boundary conditions;

[0027] S600. Dynamic current-carrying capacity optimization:

[0028] Determine the maximum current that the conductor can withstand according to the equivalent heat dissipation area method. The calculation formula is as follows:

[0029]

[0030] where, I max is the maximum current that the conductor can withstand under the condition of uneven current distribution, I uniform is the current that the conductor can withstand under the condition of uniform current distribution, A eff is the actual effective heat dissipation area, A eff = η * A coating + (1 - η)A bare , A coating is the area of the coating, A bare is the area of the bare wire, A uniform is the reference heat dissipation area under the condition of uniform heat dissipation;

[0031] Determine the dynamic current-carrying capacity according to the iterative algorithm, including the following steps:

[0032] S610. Input the environmental parameters including the environmental temperature T air , wind speed v, the heat dissipation area S of the overhead wire, and the coating parameters including the coating cycle number n, the convective heat transfer coefficient h between the overhead wire and the air;

[0033] S620. Calculate the Joule heat Q at the current I joule = I 2 R, where R is the resistance;

[0034] S630. Solve the non-uniform heat conduction equation to obtain the highest temperature T max ;

[0035] S640. Compare the magnitude of T max with the limit temperature T limit If Tmax >T limit , calculate the new current according to the reduced current proportionally

[0036] S650. Replace the current current I with the new current I and return to step S620, and iterate until |T new -T max -T limit | < 1 °C, and output the new current I new as the dynamic current-carrying capacity.

[0037] Furthermore, for the axially segmented coated overhead conductor, the geometry is defined as follows: along the axial direction of the conductor, the surface is divided into periodic units, with each period being 30 cm, and within each period, the coated area length is 20 cm and the uncoated area length is 10 cm, and the circumferential direction is uniformly coated; the parametric representation is: the coating coverage coating thickness h c = 100 μm;

[0038] For the mesh-shaped partially covered mesh-coated overhead conductor, the geometry is defined as follows: the surface is coated with a square mesh with a side length L = 5 mm and a line width w = 1 mm; the parametric representation is: the coating coverage coating thickness h c = 100 μm.

[0039] Furthermore, the method further includes the following steps:

[0040] S700. Thermal stress calculation and analysis:

[0041] Modeling of local thermal expansion differences;

[0042] Temperature field input: Import the temperature distribution T(x, y, z) calculated by the heat conduction model into the structural mechanics module;

[0043] Thermal strain calculation, the formula is as follows:

[0044] ε thermal = α * (T - T ref )

[0045] where ε thermal is the thermal strain, α is the linear thermal expansion coefficient, taking 8 - 10 6 K -1 for the coating, and taking 23 * 10 -6 K -1 for the bare conductor, and T ref is the reference temperature;

[0046] Stress concentration factor calculation, the formula is as follows:

[0047]

[0048] Among them, K t is the stress concentration coefficient, α′ is the coating edge defect size, and ρ′ is the radius of curvature;

[0049] Finite element stress simulation: The contact is set as no-slip bonded contact at the coating-conductor interface, and the mesh is encrypted at the coating edge and mesh intersection points, with a minimum element size of 0.1 mm.

[0050] The present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for determining the dynamic current-carrying capacity of the temperature-reducing and capacity-increasing overhead conductor as described above are implemented.

[0051] The present invention also provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for determining the dynamic current-carrying capacity of the temperature-reducing and capacity-increasing overhead conductor as described above are implemented.

[0052] A temperature-reducing and capacity-increasing overhead conductor, a method for determining the dynamic current-carrying capacity, a medium, and a device provided by the present invention have the following beneficial effects:

[0053] (1) By setting the overhead conductor to adopt a three-layer composite structure, the outer layer is a passive temperature-reducing coating with a thickness of 50-200 μm, having a micro-nano structure on the surface to enhance mid-infrared radiation, an emissivity ≥ 0.92, and being subjected to hydrophobic modification treatment to make the contact angle > 120°; the middle layer is a high-conductivity aluminum alloy conductor layer, and the inner layer is a high-strength galvanized steel core; a directional heat conduction path is formed between the coating and the conductor layer through a gradient thermal conductivity material, and the thermal conductivity of the gradient material increases from the coating to the conductor layer; the coating application method is axial segmented coating or mesh coating; this overhead conductor can effectively improve the current-carrying capacity of the line, optimize the power transmission design of the line, and has the following advantages: This overhead conductor can perform distributed temperature measurement by efficiently using existing overhead power transmission line monitoring devices, effectively reducing equipment costs and simplifying the maintenance process. Its simplified hardware structure reduces the maintenance difficulty and cost. At the same time, through accurate temperature monitoring and dynamic adjustment of the heat dissipation efficiency, the reliability of the power grid is significantly improved, and faults caused by overheating are avoided. In addition, this overhead conductor has wide applicability, can adapt to various environments, fully exerts the potential of the power transmission line, can increase the annual current-carrying capacity of the power transmission line by 15-25%, significantly reduce the wire temperature rise and sag change, and provide a better solution for the intelligent transformation of the UHV power grid.

[0054] (2) The present invention constructs a finite element model through geometric modeling of the overhead conductor, correction of the heat conduction model, and correction of the heat conduction equation, and optimizes the dynamic current-carrying capacity. The maximum current that the conductor can withstand is determined according to the equivalent heat dissipation area method, and the dynamic current-carrying capacity is determined according to the iterative algorithm. Based on the theoretical calculation results and actual operation data, by comparing the current-carrying capacity and temperature rise characteristics of the wire before and after coating, a quantitative index of the capacity increase effect can be obtained. Description of the Drawings

[0055] Figure 1 is a schematic structural diagram of the overhead conductor with temperature reduction and capacity increase by axial segmented coating of the present invention;

[0056] Figure 2 is a schematic structural diagram of the overhead conductor with temperature reduction and capacity increase by mesh coating of the present invention;

[0057] Figure 3 is a structural block diagram of the computer device of the embodiment of the present invention. Detailed Embodiments

[0058] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings provided by the present invention. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0059] Embodiment 1

[0060] This embodiment provides an overhead conductor with temperature reduction and capacity increase. The overhead conductor adopts a three-layer composite structure. The outer layer is a passive temperature reduction coating with a thickness of 50-200 μm, having a micro-nano structure on the surface to enhance mid-infrared radiation, an emissivity ≥ 0.92, and being subjected to hydrophobic modification treatment to make the contact angle > 120°; the middle layer is a high-conductivity aluminum alloy conductor layer, and the inner layer is a high-strength galvanized steel core; a directional heat conduction path is formed between the coating and the conductor layer through a gradient heat conduction material, and the thermal conductivity of the gradient material increases from the coating to the conductor layer; the coating method of the coating is axial segmented coating or mesh coating.

[0061] This embodiment determines the relationship between the coating thickness of the passive temperature reduction material and the temperature reduction effect and the optimal coating method: By combining numerical simulation and on-site testing, gradually change the coating method of the coating, observe and record the temperature rise of the wire. Draw a relationship curve between the coating method and the temperature rise of the wire, determine the trend of the temperature rise reduction of the wire under different coating methods of the coating within a certain range, and the situation where the temperature reduction effect tends to saturate when the coating thickness reaches a certain critical value. According to the test results of different types of transmission wires, determine their respective optimal coating methods.

[0062] Monitoring shows that this overhead conductor can effectively increase the current-carrying capacity of the line, optimize the transmission design of the line, and has the following advantages: This overhead conductor can perform distributed temperature measurement by efficiently using existing overhead transmission line monitoring devices, effectively reducing equipment costs and simplifying the maintenance process. Its simplified hardware structure reduces the maintenance difficulty and cost. At the same time, through accurate temperature monitoring and dynamic adjustment of the heat dissipation efficiency, the reliability of the power grid is significantly improved, and faults caused by overheating are avoided. In addition, this overhead conductor has wide applicability, can adapt to various environments, give full play to the potential of the transmission line, can increase the annual average current-carrying capacity of the transmission line by 15 - 25%, significantly reduce the wire temperature rise and sag change, and provide a better solution for the intelligent transformation of the UHV power grid.

[0063] In one embodiment, referring to the attached Figure 1 As shown, the axial segmented coating method is as follows: Periodic coating units are arranged along the axial direction of the conductor. Each period includes a coating area with a length of 20 cm and an uncoated area with a length of 10 cm. The coating area is circumferentially fully covered, and the uncoated area exposes the conductor layer circumferentially. The coating period repeats to cover the entire length of the conductor.

[0064] In one embodiment, referring to the attached Figure 2 As shown, the mesh coating method is as follows: Square grids with a side length of 5 mm are formed on the surface of the conductor. The grid line width is 1 mm. The coating thickness at the grid intersection points is 1.2 - 1.5 times the thickness of the edge area. The area ratio of the uncoated area is 76%.

[0065] In a preferred embodiment, a flexible transition layer is provided at the interface between the coating layer and the conductor layer, and its elastic modulus is 20% - 30% of the coating material; the grid intersection points of the mesh coating are rounded, and the rounding radius ≥ 0.2 mm; the stress distribution at the edge of the coating area is optimized through finite element simulation to ensure that the local maximum stress ≤ 200 MPa. In this embodiment, the above measures can suppress the concentration of thermal stress.

[0066] Embodiment 2

[0067] This embodiment provides a method for determining the dynamic current-carrying capacity of a cooling and capacity-increasing overhead conductor, including the following steps:

[0068] S100. Geometrically model the overhead conductor.

[0069] Specifically, referring to the attached Figure 1 As shown, for an axially segmented coated overhead conductor with 1 / 3 of the length uncoated and 2 / 3 of the length coated, the geometric definition is: Along the axial direction of the conductor, the surface is divided into periodic units, with each 30 cm as a period. In each period, the coating area has a length of 20 cm and the uncoated area has a length of 10 cm, and the circumferential direction is uniformly fully coated; parametric representation is: coating coverage Coating thickness h c = 100 μm.

[0070] Refer to the appendix Figure 2 As shown, for the meshed coated overhead conductor with partial coverage in a grid pattern, the geometric definition is: a square grid with a surface coating side length L = 5 mm and line width w = 1 mm; the parametric representation is: coating coverage Coating thickness h c = 100 μm.

[0071] S200. Modify the heat conduction model:

[0072] Calculation of non-uniform coating equivalent emissivity:

[0073] ε eff = η * ε coating + (1 - η) * ε bare

[0074] Where, ε eff is the equivalent emissivity, ε coating is the coating emissivity, with a value of 0.92, and ε bare is the bare conductor emissivity, with a value of 0.3;

[0075] Calculation of equivalent convective heat transfer coefficient:

[0076] h conv，eff = η * h coating + (1 - η) * h bare

[0077] Where, h conv,eff is the equivalent convective heat transfer coefficient, h coating is the convective correction coefficient on the coating surface, h bare is the standard convective coefficient of the bare conductor, and h bare = 5.6 + 3.8v, where v represents the wind speed.

[0078] S300. Modify the heat conduction equation:

[0079] The three-dimensional non-uniform heat conduction equation is as follows:

[0080]

[0081] Where, k(x, y, z) is the spatially distributed thermal conductivity, taking the thermal conductivity of the coating in the coated area and the thermal conductivity of the bare conductor in the uncoated area, ρ is the mass density of the object, c p is the specific heat capacity of the object, T is the temperature, and Q joule is the Joule heat generation rate per unit volume.

[0082] S400. Build a finite element model:

[0083] Import the 3D CAD model of the conductor, such as an overhead conductor with a diameter D = 20 mm and a length L = 1 m.

[0084] Create the coating geometric features: For axial segmented coating, use periodic Boolean operations to cut the surface; for mesh coating, generate the mesh by cross-line cutting.

[0085] Assign material properties to the coating area.

[0086] % Example of COMSOL material parameters

[0087] material('coating').propertyGroup('def').set('thermal_conductivity', 0.5); % W / (m·K)

[0088] material('coating').propertyGroup('def').set('emissivity', 0.92);

[0089] Define the boundary conditions.

[0090] % Radiation boundary condition (only for the coating area)

[0091] surface1 = mphgetselection(model.geom('geom1').feature('surf1'));

[0092] model.physics('ht').feature('rad1').selection.set(surface1);

[0093] model.physics('ht').feature('rad1').set('SurfaceEmissivity', 0.92);

[0094] S600, Dynamic current-carrying capacity optimization:

[0095] Determine the maximum current that the conductor can withstand according to the equivalent heat dissipation area method. The calculation formula is as follows:

[0096]

[0097] where, I max is the maximum current that the conductor can withstand under the condition of uneven current distribution, and I uniform is the current that the conductor can withstand under the condition of uniform current distribution, A effis the actual effective heat dissipation area, A eff = η * A coating + (1 - η)A bare , A coating is the area of the coating, A bare is the area of the bare wire, A uniform is the reference heat dissipation area under uniform heat dissipation conditions;

[0098] Determine the dynamic current-carrying capacity according to the iterative algorithm, including the following steps:

[0099] S610. Input environmental parameters including environmental temperature T air , wind speed v, the heat dissipation area S of the overhead wire, coating parameters including the coating cycle number n, and the convective heat transfer coefficient h between the overhead wire and the air;

[0100] S620. Calculate the joule heat Q under the current current I joule = I 2 R, where R is the resistance;

[0101] S630. Solve the non-uniform heat conduction equation to obtain the maximum temperature T max ;

[0102] S640. Compare the magnitudes of T max and the limit temperature T limit . If T max > T limit , reduce the current proportionally to calculate the new current current

[0103] S650. Replace the current current I with the new current current I and return to step S620, and iterate until |T new - T max | < 1 °C, and output the new current current I limit as the dynamic current-carrying capacity. new In one embodiment, the method further includes the following steps:

[0104] S700. Thermal stress calculation and analysis:

[0105] Model the local thermal expansion difference;

[0106] Input of the temperature field: Import the temperature distribution T(x, y, z) calculated by the heat conduction model into the structural mechanics module;

[0107] Calculate the thermal strain, and the formula is as follows:

[0108] ε

[0109] = α * (T - T thermal ) ref )

[0110] Among them, ε thermal is the thermal strain, α is the linear thermal expansion coefficient, which takes a value of 8 - 10 for the coating 6 K -1 , and takes a value of 23×10 -6 K -1 for the bare conductor, T ref is the reference temperature, which can be selected as the initial state of the material or the temperature without thermal strain;

[0111] Calculation of the stress concentration coefficient, the formula is as follows:

[0112]

[0113] Among them, K t is the stress concentration coefficient, α′ is the size of the coating edge defect, and ρ′ is the radius of curvature;

[0114] Finite element stress simulation: The contact is set as non - slip bonded contact at the coating - conductor interface, and the mesh is encrypted at the coating edge and mesh intersection points. The specific minimum element size is 0.1 mm.

[0115] Result comparison

[0116] Coating method 1 / 3 uncoated + 2 / 3 coated Mesh coating (24% coverage) Equivalent emissivity <![CDATA[ε eff = 0.72]]> <![CDATA[ε eff = 0.48]]> Increase in current-carrying capacity 8.2％ 4.5％ Maximum stress (MPa) 152 (concentrated at the edge of the uncoated area) 218 (stress concentration at the grid intersection) Cost savings 33% material cost 76% material cost

[0117] Experimental verification

[0118] Infrared thermal imaging test: Use a high - resolution infrared camera (such as FLIR A8580) to take the temperature distribution on the wire surface, and compare the simulated and measured temperature fields. Calculate the temperature distribution uniformity index:

[0119]

[0120] Among them, U is the temperature distribution uniformity, σ T is the standard deviation of temperature, T avg is the average temperature, and U>0.95 is qualified.

[0121] Stress measurement: Paste fiber Bragg grating sensors (FBG) on the wire surface to measure the local strain. The allowable range of strain error: The deviation between the simulated value and the measured value ≤5%.

[0122] Since the existing current-carrying capacity calculation model based on the two-layer material structure of ACSR is not fully applicable to the coated transmission lines, the present invention performs a refined modeling on the cross-section of the "coating-conductor-steel core" composite structure transmission line to accurately describe its geometric structure and material properties. Under the laboratory environment, different current-carrying conditions are simulated, and parameters such as surface temperature rise, coating temperature distribution, and wire stress change are measured. The experimental results are compared with the simulation data to verify whether the influence of the coating material on the wire temperature rise is consistent with the simulation results. Taking an actual transmission line (such as a 500 kV horizontal arrangement AC transmission line in a certain place in Hubei Province) as an example, passive cooling coatings with different thicknesses are coated on some phase conductors, and another phase is used as a comparison. The established current-carrying capacity calculation model is used to calculate the temperatures of each phase conductor under different currents and compare them with the measured temperatures to verify the accuracy of the model. At the same time, the influencing factors of the current-carrying capacity of the composite structure transmission line are analyzed. Based on the theoretical calculation results and actual operation data, by comparing the current-carrying capacity and temperature rise characteristics of the wire before and after coating, a quantitative index of the capacity increase effect can be obtained.

[0123] Embodiment 3

[0124] This embodiment provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for determining the dynamic current-carrying capacity of the cooling and capacity-increasing overhead wire described above are implemented.

[0125] Wherein, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), a random access memory (RAM), a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), etc.; the storage medium can also include a combination of the above types of memories.

[0126] Embodiment 4

[0127] This embodiment provides a computer device, which includes: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for determining the dynamic current-carrying capacity of the cooling and capacity-increasing overhead wire described above are implemented.

[0128] Such as Figure 3As shown, the computer device may include: at least one processor 71, such as a CPU (Central Processing Unit), at least one communication interface 73, a memory 74, and at least one communication bus 72. Among them, the communication bus 72 is used to realize the connection and communication between these components. Among them, the communication interface 73 may include a display screen and a keyboard. Optionally, the communication interface 73 may also include a standard wired interface and a wireless interface. The memory 74 may be a high-speed RAM memory (Random Access Memory, volatile random access memory), or a non-volatile memory, such as at least one disk memory. Optionally, the memory 74 may also be at least one storage device located far from the aforementioned processor 71. Among them, an application program is stored in the memory 74, and the processor 71 calls the program code stored in the memory 74 to execute any of the above method steps.

[0129] Among them, the communication bus 72 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The communication bus 72 can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 3 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0130] Among them, the memory 74 may include a volatile memory, such as a random-access memory (RAM); the memory may also include a non-volatile memory, such as a flash memory, a hard disk drive (HDD) or a solid-state drive (SSD); the memory 74 may also include a combination of the above types of memories.

[0131] Among them, the processor 71 may be a central processing unit (CPU), a network processor (NP), or a combination of a CPU and an NP.

[0132] Among them, the processor 71 may further include a hardware chip. The above-mentioned hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The above-mentioned PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0133] Optionally, the memory 74 is further configured to store program instructions. The processor 71 may call the program instructions to implement the method for determining the dynamic current-carrying capacity of the cooling and capacity-increasing overhead conductor as in the present invention.

[0134] Those skilled in the art of the present technology should understand that the present invention may be implemented in many other specific forms without departing from the spirit and scope of the present invention. Based on the embodiments of the present invention, any changes and modifications made by those of ordinary skill in the art of the present invention according to the above disclosure shall fall within the protection scope of the claims.

Claims

1. A temperature reduction and capacity increase overhead conductor, characterized in that: The overhead conductor adopts a three-layer composite structure, the outer layer is a passive cooling coating with a thickness of 50-200μm, the surface has a micro-nano structure that enhances mid-infrared radiation, the emissivity is ≥0.92, and the contact angle is greater than 120° after hydrophobic modification; the middle layer is a high-conductivity aluminum alloy conductor layer, and the inner layer is a high-strength galvanized steel core; a directional heat conduction path is formed between the coating and the conductor layer through a gradient thermal conductive material, and the thermal conductivity of the gradient material increases from the coating to the conductor layer; the coating is applied in an axial segmented coating or a mesh coating.

2. The temperature reduction and capacity increase overhead conductor according to claim 1, characterized in that: The axial segmented coating method is: periodic coating units are set along the axial direction of the conductor, each period includes a coated area with a length of 20 cm and an uncoated area with a length of 10 cm, the coated area is fully covered circumferentially, and the uncoated area has a circumferentially exposed conductor layer, and the coating cycle is repeated to cover the entire length of the conductor.

3. The temperature reduction and capacity increase overhead conductor according to claim 1, characterized in that: The mesh coating method is: forming a square grid with a side length of 5 mm on the surface of the conductor, the grid line width is 1 mm, the coating thickness at the intersection of the grid is 1.2-1.5 times the thickness of the edge area, and the area of ​​the uncoated area accounts for 76%.

4. The temperature reduction and capacity increase overhead conductor according to claim 1, characterized in that: A flexible transition layer is arranged at the interface between the coating layer and the conductor layer, and its elastic modulus is 20%-30% of the coating material.

5. The temperature reduction and capacity increase overhead conductor according to claim 4, characterized in that: The intersection points of the mesh coating are rounded, and the fillet radius is ≥ 0.2mm.

6. The method for determining the dynamic current carrying capacity of a temperature-reducing and capacity-increasing overhead conductor according to any one of claims 1 to 5, characterized in that: The steps include: S100, geometric modeling of overhead wires; S200, modify the heat conduction model: Calculation of equivalent emissivity of non-uniform coating: e eff =h*e coating +(1-n)*e bare Among them, ε eff is the equivalent emissivity, ε coating is the coating emissivity, which is 0.92, ε bare is the emissivity of the bare wire, which is 0.3; Calculation of equivalent convection heat transfer coefficient: h conv，eff =η*h coating +(1-h)*h bare Among them, h conv，eff is the equivalent convection heat transfer coefficient, h coating is the coating surface convection correction factor, h bare is the standard convection coefficient of bare conductor, h bare =5.6+3.8v, v represents wind speed; S300, correct the heat conduction equation: The three-dimensional non-uniform heat conduction equation is as follows: Where k(x, y, z) is the spatially distributed thermal conductivity, the thermal conductivity of the coating is taken in the coated area, the thermal conductivity of the bare wire is taken in the uncoated area, ρ is the mass density of the object, c p is the specific heat capacity of the object, T is the temperature, Q joule is the Joule heat generation rate per unit volume; S400, build finite element model: Import the 3D CAD model of the conductor; Create coating geometry features: for axial segmented coating, use periodic Boolean operations to cut the surface; for mesh coating, generate the mesh by cross-line cutting; Assign material properties to the coating area; Define boundary conditions; S600, Dynamic Ampacity Optimization: The maximum current that a conductor can withstand is determined by the equivalent heat dissipation area method. The calculation formula is as follows: Among them, I max I is the maximum current that the conductor can withstand when the current distribution is uneven. uniform A is the current that the conductor can withstand when the current is evenly distributed. eff is the actual effective heat dissipation area, A eff =η*A coating +(1-η)A bare , A coating is the coating area, A bare is the area of ​​the bare conductor, A uniform It is the reference heat dissipation area under uniform heat dissipation conditions; Determining the dynamic current carrying capacity according to the iterative algorithm includes the following steps: S610, input environmental parameters including ambient temperature T air , wind speed v, overhead conductor heat dissipation area S, coating parameters include coating cycle number n, convection heat transfer coefficient h between overhead conductor and air; S620, calculate the Joule heat Q under the current I joule =I 2 R, R is the resistance; S630, solve the non-uniform heat conduction equation and obtain the maximum temperature T max ; S640, Compare T max With limit temperature T limit The size of T max >T limit , calculate the new current by proportionally reducing the current S650, the new current I new Replace the current current I and return to step S620, and iterate until |T max -T limit |<1℃, output new current I new As dynamic current carrying capacity.

7. The method for determining the dynamic current carrying capacity of the overhead conductor for temperature reduction and capacity increase according to claim 6 is characterized in that: For the axial segmented coated overhead conductor, the geometry is defined as follows: along the conductor axis, the surface is divided into periodic units, each 30 cm is a period, in each period, the length of the coated area is 20 cm, the length of the uncoated area is 10 cm, and the circumference is uniformly fully coated; the parameterization is: coating coverage Coating thickness h c =100 μm; For the mesh-like partially covered overhead conductor, the geometry is defined as: a square grid with a surface coating side length L = 5 mm and a line width w = 1 mm; the parameterization is: coating coverage Coating thickness h c =100μm.

8. The method for determining the dynamic current carrying capacity of the overhead conductor for temperature reduction and capacity increase according to claim 6 is characterized in that: The method further comprises the steps of: S700, thermal stress calculation and analysis: Modeling of local thermal expansion differences; Temperature field input: Import the temperature distribution T(x, y, z) calculated by the heat conduction model into the structural mechanics module; Thermal strain calculation, the formula is as follows: e thermal =α*(TT ref ) Among them, ε thermal is the thermal strain, α is the linear thermal expansion coefficient, which is 8-10 for the coating 6 K -1 For bare wire, the value is 23*10 -6 K -1 , T ref is the reference temperature; The stress concentration factor is calculated using the following formula: Among them, K t is the stress concentration factor, α′ is the coating edge defect size, and ρ′ is the curvature radius; Finite element stress simulation: The contact setting is that the interface between the coating and the conductor adopts non-slip bonded contact, the mesh is encrypted at the edge of the coating and the intersection of the mesh, and the minimum unit size is 0.1 mm.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for determining the dynamic current carrying capacity of overhead conductors for reducing temperature and increasing capacity as described in any one of claims 6 to 8 are implemented.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for determining the dynamic current carrying capacity of the overhead conductor for reducing temperature and increasing capacity as described in any one of claims 6-8 are implemented.

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