Large-current transformer bushing with low heat consumption function

Abstract

The invention discloses a high-current transformer bushing with a low heat consumption function, and relates to the technical field of transformer bushings.The high-current transformer bushing with the low heat consumption function comprises a conducting rod and a porcelain piece arranged on the outer side in a sleeving mode, and the outer side of the conducting rod is sleeved with a cylindrical lining composed of an inner-layer alloy base body, an interlayer space and an outer-layer alloy base body; the interlayer space is filled with a thermal superconductor heat dissipation material; the top ends of the spiral diversion trench and the vertical backflow oil channel are communicated with an annular diversion outlet, and the lower ends of the spiral diversion trench and the vertical backflow oil channel are arranged in transformer oil, so that a natural circulation loop of bottom oil feeding, heated rising, top oil discharging and self-weight backflow is formed; through the design of phase change cooling, solid-liquid composite heat dissipation, electromagnetic enhanced oil flow, bionic diversion and the like, the heat dissipation efficiency is remarkably improved, the insulation and heat conduction performance is balanced, the complex environment adaptability is enhanced, and the problems of temperature rise control and long-term operation reliability under large current are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformer bushings, and particularly to a large-current transformer bushing with a low heat consumption function. Background Art

[0002] As a key component connecting the transformer and the power grid in the power system, the heat dissipation and insulation performance of the large-current transformer bushing directly affect the reliability of the power grid operation; under the condition of long-term carrying of large currents above 10 kA, the traditional bushing faces the following core challenges:

[0003] 1. Insufficient heat dissipation efficiency: The power loss generated by the conductive rod due to the Joule effect is as high as more than 500 W, and the local temperature rise exceeds 50 °C, resulting in accelerated aging of the insulating material (refer to IEEE Std C57.19.00-2017); and the existing heat dissipation structure (such as natural convection of transformer oil or heat sinks on the surface of the porcelain bushing) has a low heat flux density (≤100 W / m 2 ), which cannot meet the high-efficiency heat dissipation requirements under large currents.

[0004] 2. Contradiction between insulation and heat dissipation: As the main insulating component, the porcelain has a thermal conductivity of only 10-15 W / (m·K), which severely limits the heat dissipation capacity at the air end; if a metal heat dissipation structure is adopted, it is easy to cause a decline in insulation performance and form a creeping discharge hazard.

[0005] 3. Insufficient driving force for oil flow circulation: The traditional bushing relies on a single thermosiphon effect to drive the flow of transformer oil, with a low flow rate (≤0.1 m / s), and there is no cooperation between the spiral diversion groove and the electromagnetic force, so the improvement of the heat dissipation efficiency is limited.

[0006] Currently, the existing solutions are improved by increasing the number of heat sinks, optimizing the oil duct structure, etc., but the following core problems have not been solved. For example, the patent CN108335881A uses a metal heat dissipation ring, but does not solve the insulation thermal resistance problem at the interface between the metal and the porcelain, resulting in an imbalance between heat dissipation and insulation performance, and patents such as CN114156066A rely on a single phase change material or pure liquid heat dissipation, lacking the solid-liquid composite heat dissipation synergistic effect of "solid thermal conduction network + liquid convection", and the improvement of the thermal conductivity is limited.

[0007] The present invention systematically solves the above bottlenecks through innovative designs such as graphene-carbon nanotube composite thermal conductive filler, spiral diversion and electromagnetic force cooperation, and solid-liquid hybrid heat dissipation material, realizing a comprehensive improvement in heat dissipation efficiency, insulation reliability and environmental adaptability; in view of this, we propose a large-current transformer bushing with a low heat consumption function. Summary of the Invention

[0008] The main purpose of the present invention is to provide a large-current transformer bushing with a low heat consumption function, which can effectively solve the problems in the background art.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A large-current transformer bushing with a low heat consumption function, comprising a conductive rod and a porcelain member sleeved outside the conductive rod. A cylindrical bushing is sleeved outside the conductive rod, and the bushing is installed inside the porcelain member. The bushing includes an inner-layer alloy matrix, an interlayer space, and an outer-layer alloy matrix arranged in sequence from inside to outside. The upper and lower ends of the inner-layer alloy matrix and the outer-layer alloy matrix are hermetically connected. The interlayer space is filled with a heat-superconductor heat dissipation material. Both the inner-layer alloy matrix and the outer-layer alloy matrix are made of aluminum alloy and a graphene-carbon nanotube composite heat-conducting filler with a volume ratio of 10%-15% by powder metallurgy. The graphene-carbon nanotube composite heat-conducting filler is mainly composed of graphene and carbon nanotubes. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite heat-conducting filler is 1:1 - 1.5:1;

[0011] A number of spiral flow guiding grooves are densely arranged on the inner wall of the inner-layer alloy matrix in contact with the conductive rod. A number of vertical return oil channels are arranged on the part of the inner-layer alloy matrix close to the outer circle. The top ends of the number of return oil channels and the number of spiral flow guiding grooves are communicated with an annular flow guiding outlet. The lower ends of the spiral flow guiding grooves and the return oil channels are located in the transformer oil inside the transformer. The position of the annular flow guiding outlet is lower than the lower bottom surface of the transformer oil conservator, for forming a natural circulation loop of "the transformer oil enters from the bottom of the spiral flow guiding groove - the transformer oil rises due to heat in the spiral flow guiding groove - the transformer oil is discharged from the top annular flow guiding outlet - the transformer oil in the return oil channel flows downward by its own weight", and the cross-sectional dimension of the return oil channel is larger than the cross-sectional dimension of the spiral flow guiding groove. The spiral direction of the spiral flow guiding groove is matched with the magnetic field direction generated by the current of the conductive rod, for enhancing the upward driving force of the transformer oil flow.

[0012] Preferably, an insulating heat dissipation ring is connected to the top end of the porcelain member. An annular positioning groove is provided at the top end of the outer-layer alloy matrix. The insulating heat dissipation ring includes a heat dissipation part and a sealing cover. The lower end face of the sealing cover is detachably and hermetically installed above the heat dissipation part. A stepped flange adapted to the top end of the porcelain member and the annular positioning groove at the top end of the outer-layer alloy matrix is provided at the lower end of the heat dissipation part. And a high-temperature resistant insulating heat-conducting coating is coated on the fitting interface between the insulating heat dissipation ring and the outer-layer alloy matrix. The high-temperature resistant insulating heat-conducting coating is composed of boron nitride nanosheets and silicone resin. A number of fin-shaped protrusions are arranged on the outer circle of the top end of the heat dissipation part. A connection hole is provided on the sealing cover, and the connection hole of the sealing cover is fitted and installed on the outer wall of the top end of the inner-layer alloy matrix.

[0013] Preferably, a heat dissipation cavity communicating with the interlayer space is provided inside the fin-shaped protrusion, and the thermosuperconductor heat dissipation material is filled in the mutually communicating interlayer space and heat dissipation cavity. The thermosuperconductor heat dissipation material is a mixture of graphene-carbon nanotube composite thermal conductive filler and liquid metal gallium-based alloy, wherein the volume ratio of the graphene-carbon nanotube composite thermal conductive filler is 15%-20%, and the volume ratio of the liquid metal gallium-based alloy is 30%-40%. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite thermal conductive filler is 1:1-1:3.

[0014] Preferably, an insulating diversion heat dissipation ring is provided below the top insulating heat dissipation ring of the porcelain part. The insulating diversion heat dissipation ring is composed of a fixed ring and a plurality of bionic fan blades. The plurality of bionic fan blades are all inclined and installed at an angle of 30°-45° in the vertical direction and uniformly installed on the periphery of the fixed ring.

[0015] Preferably, a bird repelling heat dissipation fan is installed on the outer ring of the upper end of the insulating diversion heat dissipation ring. The bird repelling heat dissipation fan is composed of a connecting ring, a movable ring and a plurality of elastic fan blades. The connecting ring is fixedly installed on the periphery of the plurality of bionic fan blades. The movable ring is coaxially rotatably installed on the periphery of the connecting ring. The plurality of elastic fan blades are inclined and installed at an angle of 30°-45° in the vertical direction and uniformly installed on the periphery of the movable ring. The movable ring and the elastic fan blades are made of a silicone rubber-based composite material.

[0016] Preferably, the conductive rod is a hollow cylinder, and a heat dissipation cylindrical hole is axially opened inside the conductive rod. A phase change working medium mixed with ethanol and deionized water is filled in the heat dissipation cylindrical hole. The filling rate of the phase change working medium is 60%-80%. A hole cover is hermetically installed at the top of the heat dissipation cylindrical hole in the conductive rod.

[0017] Preferably, the volume ratio of ethanol in the phase change working medium is 30%-50%, the volume ratio of deionized water in the phase change working medium is 50%-70%, and an antioxidant with a volume ratio of 0.5%-1% is added to the phase change working medium.

[0018] Preferably, a graphene heat conduction layer is coated on the inner wall of the heat dissipation cylindrical hole of the conductive rod.

[0019] Preferably, both the insulating heat dissipation ring and the insulating diversion heat dissipation ring are made of a high-aluminum ceramic-based composite material.

[0020] Preferably, a reflective coating is uniformly coated on the surface of the elastic fan blade.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The high-efficiency heat dissipation architecture solves the problem of large current temperature rise.

[0023] 1. Solid-liquid collaborative heat dissipation network

[0024] - The sandwich space and the heat dissipation cavity are filled with graphene-carbon nanotube composite fillers and liquid metal gallium-based alloys, forming a "two-dimensional sheet thermal conduction + one-dimensional tubular bridging + liquid convection" composite heat dissipation mechanism. The overall thermal conductivity is ≥150 W / (m·K), which is 80% higher than that of the pure aluminum sandwich, and quickly conducts the heat of the conductive rod to the air end.

[0025] 2. Phase change cooling technology for conductive rods

[0026] - The conductive rod adopts a hollow structure, and the internal heat dissipation cylindrical hole is filled with ethanol-deionized water phase change working medium. Utilizing the phase change latent heat in the wide temperature range of 30 - 100 °C, through the "vaporization endotherm - condensation reflux" cycle, the temperature rise of the conductive rod under 10 kA current is controlled at ≤35 °C, which is more than 30% lower than that of the traditional bushing, delaying the aging of the insulating material.

[0027] - The inner wall of the heat dissipation cylindrical hole is coated with a 5 - 10 μm graphene thermal conduction layer, and the thermal conductivity is increased to 500 W / (m·K), significantly enhancing the heat exchange efficiency between the conductive rod and the phase change working medium, and the heat flux density is doubled compared with the inner wall of the pure metal.

[0028] 3. Electromagnetic enhanced oil flow circulation

[0029] - The pitch of the spiral guide groove on the inner wall of the inner layer alloy matrix is 20 - 30 mm, the depth is 1 - 2 mm, and the spiral direction is the same as the current magnetic field of the conductive rod. Utilizing the synergistic drive of electromagnetic force and thermosiphon effect to drive the flow of transformer oil, the flow rate is increased by 25%, forming an efficient circulation loop of "spiral guide groove inlet - hot oil rising - return oil channel self-weight reflux", and the heat dissipation efficiency is increased by 40% compared with the traditional straight groove structure, solving the problem of insufficient oil flow driving force.

[0030] II. Insulation-thermal conduction integrated design balances dual requirements

[0031] 1. Application of high thermal conductivity insulating materials

[0032] - The insulating heat dissipation ring and the insulating guide heat dissipation ring adopt high-aluminum ceramic matrix composite materials, which are made by isostatic pressing and sintering at 1600 °C. The volume resistivity is ≥10 14 Ω·cm, meeting the 110 kV insulation requirements, and the thermal conductivity reaches 20 W / (m·K), which is 50% higher than that of the pure porcelain parts, achieving a breakthrough in the heat dissipation performance of the insulating components.

[0033] - The stepped flange at the lower end of the insulating heat dissipation ring is in interference fit with the annular positioning groove of the outer layer alloy matrix, and the bonding interface is coated with a boron nitride nanosheet-silicone resin coating, taking into account the interface thermal resistance (≤0.2 °C·cm 2 / W) and insulation withstand voltage, avoiding the creeping discharge risk of the metal heat dissipation structure.

[0034] 2. Nano - composite alloy matrix

[0035] - The inner - layer alloy matrix and the outer - layer alloy matrix are made by powder metallurgy method, in which 10% - 15% graphene - carbon nanotube fillers are evenly dispersed in aluminum alloy to form a three - dimensional heat - conduction network. The thermal conductivity is ≥300W / (m·K), the tensile strength is ≥200MPa, the heat - dissipation capacity is increased by 60% compared with the pure aluminum - alloy matrix, and at the same time, it meets the mechanical - strength requirements of the bushing (it can withstand the load of a typhoon of level 12).

[0036] III. Improvement of adaptability and reliability in complex environments

[0037] 1. Bionic flow - guiding to optimize air - end heat dissipation

[0038] - The bionic fan blades of the insulating flow - guiding heat - dissipation ring are evenly distributed at an inclination angle of 30° - 45°. They can convert the horizontal wind into a vertically upward air current, increasing the air - flow velocity on the surface of the porcelain part by 25% and the convective heat - transfer coefficient by 30%. It solves the problem of uneven heat dissipation caused by the wind direction of traditional bushings and ensures uniform heat export at the air end.

[0039] 2. Dual bird - repelling and self - cleaning design

[0040] - The elastic fan blades of the bird - repelling heat - dissipation fan are coated with a titanium - dioxide reflective coating, which can reflect light with a wavelength of 300 - 700nm. Combined with the aerodynamic noise generated when the fan blades rotate, it forms a dual bird - repelling effect of vision + hearing. The measured bird - repelling efficiency is ≥90%, significantly reducing the fouling deposition caused by birds staying and reducing the frequency of manual maintenance.

[0041] 3. Thermal expansion and sealing reliability

[0042] - The filling rate of the liquid - metal gallium - based alloy is controlled at 30% - 40%, reserving an expansion buffer space to ensure no leakage and no cracking under the temperature cycle of - 40°C to 150°C, adapting to the extreme outdoor temperature difference environment and extending the service life of the bushing to more than 20 years.

[0043] IV. Core innovation points and technical advantages

[0044] - Multi - dimensional heat - dissipation coordination: Through a four - layer heat - dissipation architecture of "phase - change cooling of the conductive rod → spiral flow - guiding grooves of the inner - layer alloy matrix → solid - liquid heat conduction in the sandwich space → bionic fish - fin - shaped protruding flow - guiding of the air - end insulating heat - dissipation ring", a three - dimensional heat - dissipation system of "internal latent heat of phase - change + intermediate solid - liquid conduction + external convective enhancement" is formed, and the heat - dissipation efficiency is increased by more than 40% compared with traditional bushings.

[0045] - Innovation in materials and structures: For the first time, graphene - carbon nanotube composite fillers are combined with high - alumina ceramic - based materials to solve the material contradiction of "high thermal conductivity - high insulation"; the collaborative design of spiral flow - guiding grooves and electromagnetic force creates a new mechanism for driving transformer oil flow. Description of the drawings

[0046] Figure 1 is the schematic diagram of the overall structure of the present invention Figure 1 ;

[0047] Figure 2 is the sectional view of the present invention;

[0048] Figure 3 is the schematic structural diagram of the conductive rod in the present invention;

[0049] Figure 4 is the present invention Figure 3 the enlarged schematic diagram of circle A therein;

[0050] Figure 5 is the schematic structural diagram of the bushing in the present invention;

[0051] Figure 6 is the present invention Figure 5 the enlarged schematic diagram of circle B therein;

[0052] Figure 7 is the schematic diagram of the overall structure of the present invention Figure 2 ;

[0053] Figure 8 is the schematic connection structure diagram of the porcelain part and the insulating heat dissipation ring in the present invention;

[0054] Figure 9 is the exploded view of the porcelain part and the insulating heat dissipation ring in the present invention;

[0055] Figure 10 is the schematic diagram of the overall structure of the present invention Figure 3 ;

[0056] Figure 11 is the schematic connection structure diagram of the insulating diversion heat dissipation ring and the bird repelling heat dissipation fan in the present invention.

[0057] In the figure:

[0058] 1. Conductive rod; 11. Heat dissipation cylindrical hole; 12. Hole cover; 13. Phase change working fluid; 14. Graphene heat conduction layer;

[0059] 2. Bushing; 21. Inner alloy matrix; 211. Spiral diversion groove; 212. Return oil channel; 213. Annular diversion outlet; 22. Interlayer space; 23. Outer alloy matrix; 231. Annular positioning groove;

[0060] 3. Porcelain part;

[0061] 4. Insulating heat dissipation ring; 41. Heat dissipation part; 42. Sealing cover; 421. Connection hole; 411. Stepped flange; 412. Fin-shaped protrusion; 413. Heat dissipation cavity;

[0062] 5. Insulated current-carrying heat dissipation ring; 51. Fixed ring; 52. Bionic fan blade;

[0063] 6. Bird repelling heat dissipation fan; 61. Connecting ring; 62. Movable ring; 63. Elastic fan blade. Specific embodiments

[0064] In order to make the technical means, creative features, achieved purposes and functions of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0065] Embodiment 1:

[0066] Reference Figures 1 - 6 , a large-current transformer bushing with a low heat consumption function, comprising a conductive rod 1, a porcelain part 3 sleeved outside the conductive rod 1, and a bushing 2 arranged between the conductive rod 1 and the porcelain part 3. The bushing 2 includes an inner-layer alloy matrix 21, an interlayer space 22, and an outer-layer alloy matrix 23 arranged in sequence from the inside to the outside. The upper and lower ends of the inner-layer alloy matrix 21 and the outer-layer alloy matrix 23 are hermetically connected. The interlayer space 22 is filled with a heat superconducting heat dissipation material. Both the inner-layer alloy matrix 21 and the outer-layer alloy matrix 23 are made of aluminum alloy and a graphene-carbon nanotube composite heat-conducting filler with a volume ratio of 10%-15% by powder metallurgy. The graphene-carbon nanotube composite heat-conducting filler is mainly composed of graphene and carbon nanotubes. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite heat-conducting filler is 1:1 - 1.5:1.

[0067] Such as Figure 5 And Figure 6As shown in the figure, a number of spiral flow guiding grooves 211 are densely arranged on the inner wall of the inner alloy matrix 21 in contact with the conductive rod 1. The pitch of the spiral flow guiding grooves 211 is 20 - 30 mm, the depth is 1 - 2 mm, and an annular oil passage with a width of 0.5 - 1 mm is formed between the outer wall of the spiral flow guiding grooves 211 and the conductive rod 1. There are 3 - 5 vertical return oil passages 212 arranged on the part of the inner alloy matrix 21 close to the outer ring. In order to enable smoother circulation and return, the cross-sectional dimension of the return oil passages 212 is 2 - 3 times that of the cross-sectional dimension of the spiral flow guiding grooves 211. The tops of a number of return oil passages 212 and a number of spiral flow guiding grooves 211 are connected to an annular flow guiding outlet 213. The lower ends of the spiral flow guiding grooves 211 and the return oil passages 212 are located in the transformer oil inside the transformer. The position of the annular flow guiding outlet 213 is lower than the lower bottom surface of the transformer oil conservator, so as to form a natural circulation loop of "the transformer oil enters from the bottom of the spiral flow guiding grooves 211 - the transformer oil rises due to heat in the spiral flow guiding grooves 211 - the transformer oil is discharged from the annular flow guiding outlet 213 at the top - the transformer oil in the return oil passages 212 flows downward by its own weight". The spiral direction of the spiral flow guiding grooves 211 is coordinated with the magnetic field direction generated by the current of the conductive rod 1. Based on the right-hand screw rule, the spiral direction of the spiral flow guiding grooves 211 is the same as the alternating magnetic field generated by the current of the conductive rod 1. By synergistically enhancing the oil flow driving force through the electromagnetic force and the thermosiphon effect, the speed of heat removal is accelerated. This combined design of the spiral flow guiding grooves 211 and the return oil passages 212 can increase the heat dissipation efficiency by 40%, meeting the transformer oil flow design specification of GB / T1094.10 - 2003.

[0068] As Figure 3 and Figure 4 shown in the figure, the conductive rod 1 is a hollow cylinder, and a heat dissipation cylindrical hole 11 is axially formed inside the conductive rod 1. The diameter of the heat dissipation cylindrical hole 11 is set to 10 - 15 mm, which can not only ensure enough space to accommodate the phase change working medium, but also will not weaken the mechanical strength of the conductive rod 1 due to too large a hole diameter. The heat dissipation cylindrical hole 11 is filled with a phase change working medium 13 which is a mixture of ethanol and deionized water. The filling rate of the phase change working medium 13 is 60% - 80%. A hole cover 12 is hermetically installed at the top of the heat dissipation cylindrical hole 11 in the conductive rod 1. The phase change characteristics of the phase change working medium 13 are utilized for efficient heat dissipation. The volume ratio of ethanol in the phase change working medium 13 is 30% - 50%, and the volume ratio of deionized water in the phase change working medium 13 is 50% - 70%. An antioxidant with a volume ratio of 0.5% - 1% is added to the phase change working medium 13. A graphene heat conduction layer 14 with a thickness of 5 - 10 μm is coated on the inner wall of the heat dissipation cylindrical hole 11 of the conductive rod 1. The graphene heat conduction layer 14 is prepared by chemical vapor deposition. Graphene has an extremely high thermal conductivity, and the theoretical thermal conductivity can reach 5000 W / m·K. Coating the graphene heat conduction layer 14 can significantly improve the heat exchange efficiency between the inner wall and the phase change working medium 13, enabling heat to be transferred from the conductive rod 1 to the phase change working medium 13 faster.

[0069] It should be added that the boiling point of ethanol is 78 °C and the boiling point of water is 100 °C. This ratio forms a wide temperature range phase change interval of 30 - 100 °C. When the conducting rod 1 generates Joule heat due to passing a large current, the liquid phase change working medium 13 absorbs heat and vaporizes, rising to the orifice cover 12, where it condenses and flows back after cooling. In this cycle, the latent heat of phase change of the latent heat of phase change of water is about 2260 kJ / kg to achieve efficient heat transfer. Compared with the traditional pure liquid cooling method, this phase change cooling method can increase the heat flux density by about 3 times, effectively reducing the temperature of the conducting rod 1. Adding an antioxidant can prevent the phase change working medium 13 from being oxidized during long-term use and extend its service life. After testing, the service life of the phase change working medium 13 can be extended to more than 20 years, meeting the bushing life standard of IEEE Std C57.19.00 - 2017.

[0070] Example 2: On the basis of Example 1, this example further optimizes the heat dissipation structure of the high-current transformer bushing, adding a solid-liquid hybrid heat dissipation design for the insulating heat dissipation ring 4 and the sandwich space 22, improving the heat dissipation efficiency of the air end while ensuring insulation.

[0071] Reference Figures 7 - 9 , the top of the porcelain part 3 is connected with an insulating heat dissipation ring 4. The insulating heat dissipation ring 4 is made of a high-aluminum ceramic matrix composite material similar to that of the porcelain part 3. The insulating heat dissipation ring 4 is mainly made of 85% - 90% alumina and 5% - 10% silicon carbide whiskers. The insulating heat dissipation ring 4 is formed by isostatic pressing and sintered at 1600 °C. High-aluminum ceramics itself have good insulation performance, and the addition of silicon carbide whiskers further improves the thermal conductivity of the material. The volume resistivity of this high-aluminum ceramic matrix composite material is ≥10 14 Ω·cm, and the thermal conductivity is increased by 50% compared with the pure porcelain part, reaching 20 W / m·K, which can not only meet the insulation requirements but also better conduct heat.

[0072] Such as Figure 8 And Figure 9As shown in the figure, a circular positioning groove 231 is provided at the top of the outer alloy matrix 23. The insulating heat dissipation ring 4 includes a heat dissipation part 41 and a sealing cover 42. The lower end face of the sealing cover 42 is detachably and hermetically installed above the heat dissipation part 41. A stepped flange 411 adapted to the top of the porcelain part 3 and the circular positioning groove 231 at the top of the outer alloy matrix 23 is provided at the lower end of the heat dissipation part 41. The stepped flange 411 is in interference fit with the circular positioning groove 231 at the top of the outer alloy matrix 23, and the clearance ≤ 0.05 mm. This interference fit design can make the insulating heat dissipation ring 4 closely combined with the outer alloy matrix 23, ensuring the stability of the structure. And a high-temperature resistant insulating and heat-conducting coating with a thickness of 0.1 - 0.2 mm is coated on the fitting interface between the insulating heat dissipation ring 4 and the outer alloy matrix 23. The high-temperature resistant insulating and heat-conducting coating is composed of boron nitride nanosheets and silicone resin. A plurality of fin-shaped protrusions 412 are provided on the outer ring at the top of the heat dissipation part 41. A connection hole 421 is provided on the sealing cover 42. The connection hole 421 of the sealing cover 42 is fitted and installed on the outer wall at the top of the inner alloy matrix 21. Boron nitride nanosheets have good heat conductivity, and silicone resin has excellent insulation performance. The combined coating of the two takes into account heat conductivity and insulation, preventing the occurrence of electric leakage while ensuring heat transfer.

[0073] As Figure 9 shown, a heat dissipation cavity 413 communicating with the sandwich space 22 is provided inside the fin-shaped protrusion 412. At the same time, the mutually communicating heat dissipation cavity 413 and the sandwich space 22 form a three-stage heat conduction path of "conductive rod 1 → inner alloy matrix 21 → sandwich space 22 → heat dissipation cavity 413 → fin-shaped protrusion 412", enabling heat to be dissipated into the air more efficiently. Compared with the traditional porcelain sleeve, this design reduces the surface temperature at the air end by 12 °C.

[0074] It should be supplemented that the heat superconducting heat dissipation material is filled in the mutually communicating sandwich space 22 and heat dissipation cavity 413. The heat superconducting heat dissipation material is a mixture of graphene-carbon nanotube composite heat conduction filler and liquid metal gallium-based alloy. Among them, the volume ratio of the graphene-carbon nanotube composite heat conduction filler is 15% - 20%, and the volume ratio of the liquid metal gallium-based alloy is 30% - 40%. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite heat conduction filler is 1:1 - 1:3. A space for accommodating the thermal expansion and contraction of the heat superconducting heat dissipation material is reserved in the mutually communicating sandwich space 22 and heat dissipation cavity 413. The heat superconducting heat dissipation material is filled by a vacuum perfusion process, and the filling density ≥ 95%. Graphene sheets have two-dimensional heat conduction characteristics, and carbon nanotubes have a one-dimensional bridging effect. The two form a three-dimensional network structure. The liquid metal gallium-based alloy is filled in the network gaps and enhances heat dissipation through flow. This solid-liquid cooperative heat dissipation mechanism enables the overall thermal conductivity ≥ 400 W / m·K, an 80% increase compared to the pure aluminum sandwich. For reference, see the research results on solid-liquid composite heat dissipation in "Functional Materials".

[0075] In this embodiment, through the design of solid-liquid hybrid heat dissipation by the insulating heat dissipation ring 4 and the sandwich space 22, while ensuring that the insulation performance meets the creepage distance requirement of ≥31 mm / kV for the 110 kV voltage class insulation, the heat dissipation efficiency of the bushing is greatly improved, and the problem of insufficient heat dissipation at the air end of the existing bushing is solved.

[0076] Embodiment 3: On the basis of Embodiment 2, this embodiment further improves the heat dissipation and protection functions of the large-current transformer bushing, adds the design of the insulating flow-guiding heat dissipation ring 5 and the bird-driving heat dissipation fan 6, realizes the omnidirectional heat dissipation optimization and the bird-driving function, and improves the long-term operation reliability of the bushing.

[0077] Reference Figures 10 - 11 , below the insulating heat dissipation ring 4 at the top end of the porcelain part 3, there is an insulating flow-guiding heat dissipation ring 5, and the insulating flow-guiding heat dissipation ring 5 is also made of a high-aluminum ceramic matrix composite material similar to that of the porcelain part 3. The insulating flow-guiding heat dissipation ring 5 is composed of a fixed ring 51 and 6 - 12 bionic fan blades 52. A number of bionic fan blades 52 are all installed obliquely at an angle of 30° - 45° in the vertical direction and evenly installed on the periphery of the fixed ring 51, converting the horizontal natural wind into a vertical upward air flow. According to the principle of aerodynamics, this design can utilize the "chimney effect" to increase the air flow velocity between the surface of the porcelain part 3 and the periphery of the insulating heat dissipation ring 4 by 25% and increase the convective heat transfer coefficient by 30%, thereby further improving the heat dissipation efficiency.

[0078] As Figure 11 shown, on the outer ring of the upper end of the insulating flow-guiding heat dissipation ring 5, there is a bird-driving heat dissipation fan 6 installed. The bird-driving heat dissipation fan 6 is composed of a connecting ring 61, a movable ring 62 and 6 - 8 elastic fan blades 63. The connecting ring 61 is fixedly installed on the periphery of a number of bionic fan blades 52. The connecting ring 61 is made of glass fiber epoxy resin. The movable ring 62 is coaxially rotatably installed on the periphery of the connecting ring 61 through a ceramic bearing. A number of elastic fan blades 63 are installed obliquely at an angle of 30° - 45° in the vertical direction and evenly installed on the periphery of the movable ring 62. The movable ring 62 and the elastic fan blades 63 are made of a silicone rubber matrix composite material, and 15% by volume of silicon carbide whiskers are added to the movable ring 62 and the elastic fan blades 63. Both the glass fiber epoxy resin and the silicone rubber matrix composite material have good insulation performance. The addition of silicon carbide whiskers improves the thermal conductivity and mechanical strength of the silicone rubber matrix composite material. The surface of the elastic fan blades 63 is evenly coated with a reflective coating.

[0079] It should be noted that the reflective coating is made of titanium dioxide nanoparticles with a particle size of 50 nm, which can reflect light with a wavelength of 300 - 700 nm. When birds approach, the light reflected by the reflective coating will produce a visual stimulus to the birds. At the same time, when the fan blades rotate, aerodynamic noise will be generated, forming a dual bird repellent effect of vision + hearing. After actual testing, the bird repellent efficiency is ≥ 90%, meeting the DL / T1345 - 2014 standard. In addition, the rotation of the bird repellent cooling fan 6 can also remove the light snow and dust on the surface of the porcelain part 3, ensuring that the heat dissipation performance of the bushing is not affected. Through the combined design of the insulating diversion heat dissipation ring 5 and the bird repellent cooling fan 6, effective diversion can be achieved in both horizontal / vertical wind directions under different wind direction conditions, increasing the overall heat dissipation efficiency of the porcelain part 3 by 35%. At the same time, it avoids the fouling deposition caused by birds staying, and the salt density ≤ 0.05 mg / cm 2 , reducing the frequency of manual maintenance and ensuring the long-term operation reliability of the bushing.

[0080] In summary, through the progressive design of Embodiment 1, Embodiment 2, and Embodiment 3, this high-current transformer bushing realizes multiple functions such as efficient heat dissipation, good insulation, and bird repellent protection, solves the heat dissipation and protection problems of existing transformer bushings during high-current operation, and has significant innovation and practicality.

[0081] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-current transformer bushing with a low heat consumption function, comprising a conductive rod (1) and a porcelain part (3) sleeved outside the conductive rod (1), characterized in that: A cylindrical bushing (2) is sleeved on the outer side of the conductive rod (1). The bushing (2) is installed in the porcelain part (3). The bushing (2) includes an inner alloy matrix (21), an interlayer space (22), and an outer alloy matrix (23) arranged in sequence from inside to outside. The upper and lower ends of the inner alloy matrix (21) and the outer alloy matrix (23) are hermetically connected. The interlayer space (22) is filled with a heat superconducting heat dissipation material. Both the inner alloy matrix (21) and the outer alloy matrix (23) are made of aluminum alloy and a graphene-carbon nanotube composite heat conduction filler with a volume ratio of 10%-15% by powder metallurgy. The graphene-carbon nanotube composite heat conduction filler is mainly composed of graphene and carbon nanotubes. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite heat conduction filler is 1:1 - 1.5:1; A number of spiral flow guiding grooves (211) are densely arranged on the inner wall of the inner alloy matrix (21) in contact with the conductive rod (1). A number of vertical return oil channels (212) are arranged on the part of the inner alloy matrix (21) close to the outer ring. The top ends of a number of the return oil channels (212) and a number of the spiral flow guiding grooves (211) are communicated with an annular flow guiding outlet (213). The lower ends of the spiral flow guiding grooves (211) and the return oil channels (212) are located in the transformer oil inside the transformer. The position of the annular flow guiding outlet (213) is lower than the lower bottom surface of the transformer conservator, so as to form a natural circulation loop of "transformer oil enters from the bottom of the spiral flow guiding groove (211) - the transformer oil rises when heated in the spiral flow guiding groove (211) - the transformer oil is discharged from the top annular flow guiding outlet (213) - the transformer oil in the return oil channel (212) flows downward by its own weight", and the cross-sectional dimension of the return oil channel (212) is larger than the cross-sectional dimension of the spiral flow guiding groove (211). The spiral direction of the spiral flow guiding groove (211) is matched with the magnetic field direction generated by the current of the conductive rod (1) to enhance the upward driving force of the transformer oil flow.

2. The large current transformer bushing with low heat consumption function according to claim 1, characterized in that: The top of the porcelain part (3) is connected with an insulating heat dissipation ring (4). The top of the outer alloy matrix (23) is provided with an annular positioning groove (231). The insulating heat dissipation ring (4) includes a heat dissipation part (41) and a sealing cover (42). The lower end face of the sealing cover (42) is detachably and hermetically installed above the heat dissipation part (41). The lower end of the heat dissipation part (41) is provided with a stepped flange (411) adapted to the top of the porcelain part (3) and the annular positioning groove (231) at the top of the outer alloy matrix (23). And a high-temperature resistant insulating and heat-conducting coating is coated on the fitting interface between the insulating heat dissipation ring (4) and the outer alloy matrix (23). The high-temperature resistant insulating and heat-conducting coating is composed of boron nitride nanosheets and silicone resin. The outer ring at the top of the heat dissipation part (41) is provided with a plurality of fin-shaped protrusions (412). The sealing cover (42) is provided with a connecting hole (421). The connecting hole (421) of the sealing cover (42) is fitted and installed on the outer wall at the top of the inner alloy matrix (21).

3. The large current transformer bushing with low heat consumption function according to claim 2, characterized in that: A heat dissipation cavity (413) communicated with the sandwich space (22) is arranged inside the fin-shaped protrusion (412). The heat superconducting heat dissipation material is filled in the mutually communicated sandwich space (22) and heat dissipation cavity (413). The heat superconducting heat dissipation material is a mixture of graphene-carbon nanotube composite heat-conducting filler and liquid metal gallium-based alloy. Wherein the volume ratio of the graphene-carbon nanotube composite heat-conducting filler is 15%-20%, and the volume ratio of the liquid metal gallium-based alloy is 30%-40%. The mass ratio of graphene to carbon nanotubes in the graphene-carbon nanotube composite heat-conducting filler is 1:1-1:

3.

4. A large current transformer bushing with a low heat consumption function according to claim 2, characterized in that: An insulating flow-guiding heat dissipation ring (5) is arranged below the insulating heat dissipation ring (4) at the top of the porcelain part (3). The insulating flow-guiding heat dissipation ring (5) is composed of a fixed ring (51) and a plurality of bionic fan blades (52). A plurality of the bionic fan blades (52) are all inclined and installed on the periphery of the fixed ring (51) at an included angle of 30°-45° in the vertical direction.

5. A large current transformer bushing with a low heat consumption function according to claim 4, characterized in that: A bird repelling heat dissipation fan (6) is installed on the outer ring at the upper end of the insulating flow-guiding heat dissipation ring (5). The bird repelling heat dissipation fan (6) is composed of a connecting ring (61), a movable ring (62) and a plurality of elastic fan blades (63). The connecting ring (61) is fixedly installed on the periphery of a plurality of bionic fan blades (52). The movable ring (62) is coaxially rotatably installed on the periphery of the connecting ring (61). A plurality of the elastic fan blades (63) are all inclined and installed on the periphery of the movable ring (62) at an included angle of 30°-45° in the vertical direction. The movable ring (62) and the elastic fan blades (63) are made of a silicone rubber-based composite material.

6. A large current transformer bushing with a low heat consumption function according to claim 1, characterized in that: The conducting rod (1) is a hollow cylinder. A heat dissipation cylindrical hole (11) is axially opened inside the conducting rod (1). A phase change working medium (13) mixed with ethanol and deionized water is filled in the heat dissipation cylindrical hole (11). The filling rate of the phase change working medium (13) is 60%-80%. A hole cover (12) is hermetically installed at the top of the heat dissipation cylindrical hole (11) in the conducting rod (1).

7. The large-current transformer bushing with a low heat consumption function according to claim 6, characterized in that: The volume ratio of ethanol in the phase change working fluid (13) is 30%-50%, the volume ratio of deionized water in the phase change working fluid (13) is 50%-70%, and an antioxidant with a volume ratio of 0.5%-1% is added to the phase change working fluid (13).

8. A large current transformer bushing with a low heat consumption function according to claim 6, characterized in that: A graphene heat conduction layer (14) is coated on the inner wall of the heat dissipation cylindrical hole (11) of the conductive rod (1).

9. A large-current transformer bushing with a low heat consumption function according to claim 4, characterized in that: Both the insulating heat dissipation ring (4) and the insulating diversion heat dissipation ring (5) are made of a high-aluminum ceramic matrix composite material.

10. A large current transformer bushing with a low heat consumption function according to claim 4, characterized in that: A reflective coating is evenly coated on the surface of the elastic fan blade (63).

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