Encapsulation structure for strong wind-cooled dry-type transformer winding

Abstract

The invention relates to a strong wind cooling dry-type transformer winding encapsulation structure which comprises a transformer box body, a transformer three-phase cylinder, an iron core, an iron core upper clamping piece, an iron core lower clamping piece, a lower wind shield and a heat pipe heat dissipation assembly, and the transformer three-phase cylinder is arranged on the iron core in a surrounding mode; the iron core is arranged in the transformer box body; the lower wind shield is fixedly arranged in the transformer box body; the transformer box body is divided into an upper air outlet part and a lower air supply part by the lower wind shield; a plurality of ventilation channels are formed in a high-voltage winding epoxy potting cylinder of the transformer three-phase cylinder in the axial direction. The heat pipe heat dissipation assembly is arranged on the top of the low-voltage winding epoxy potting cylinder and the top of the high-voltage winding epoxy potting cylinder of the transformer three-phase cylinder. The method has the advantages that the heat dissipation efficiency of the winding in each package is improved by increasing the convection heat dissipation area of epoxy resin and air; the air circulation path is reasonably designed, and air is fully utilized to take away heat, so that the temperature rise of the iron core and the winding is inhibited.

Description

Technical Field

[0001] The invention relates to the technical field of box-type air-cooled transformers, and in particular to a strong air-cooled dry-type transformer winding potting structure. Background Art

[0002] As one of the key equipment in the power system, power transformers are widely used in power grids of various voltage levels. They are the main components of safe transmission and economic distribution of electric energy, and play a vital role in the safe and stable operation of the power system. Their safe and reliable operation is an important guarantee for the stable operation of the power system. According to the insulating medium, power transformers can be divided into oil-immersed transformers, dry-type transformers, and gas transformers. Oil-immersed transformers usually use mineral oil as a cooling and insulating medium, and have the characteristics of good insulation performance, high heat dissipation efficiency, and large capacity. However, there are flammable and explosive safety hazards during use, and the later maintenance cost is high. They are usually used in large and medium-sized substations with high voltage level requirements. Gas transformers mainly refer to SF6 insulated transformers. Compared with oil-immersed transformers, their advantages are superior fire and explosion resistance, small maintenance requirements, and small footprint. However, they have the defects of high process requirements and high investment costs, and there are environmental risks of insulating gas leakage, which seem to bring great limitations to the widespread use of SF6 insulated transformers.

[0003] With the continuous development of dry-type transformer manufacturing technology, the insulation strength and rated capacity of dry-type transformers are constantly improving. In addition, dry-type transformers have the characteristics of superior environmental performance, strong safety and reliability, and high operating efficiency. Dry-type transformers account for an increasingly large proportion in distribution networks. Dry-type transformers are more common in voltage levels of 35kV and below, especially in applications close to load centers and with special requirements for fire safety. Especially in the past 30 years, the proportion of dry-type transformers in distribution transformers has increased rapidly: according to incomplete statistics, in developed countries and regions in the world, dry-type transformers have accounted for 40%-50% of distribution transformers. At present, the proportion of dry-type transformers in my country's major cities such as Beijing, Shanghai, and Guangzhou has reached more than 50%, and there is still a trend of continued increase.

[0004] Dry-type transformers are made of glass fiber reinforced epoxy resin and have poor thermal conductivity. In addition, the air convection heat transfer efficiency is not good, so dry-type transformers are more prone to local overheating. Compared with oil-immersed transformers, dry-type transformers still have lower capacity and shorter thermal time constants. When the transformer is overloaded or the cooling system fails, the hot spot temperature rises rapidly, causing the insulation material to deteriorate faster and reducing operational reliability. Long-term overheating can cause deformation and damage to structural parts, and in extreme cases, even cause insulation breakdown and internal overheating failures, thereby destroying the equipment and causing huge economic and social losses to users.

[0005] The hot spot temperature of dry-type transformers is an important indicator of the health level of transformers. It is the result of the mutual coupling of electromagnetic fields, temperature fields, and flow fields. If we can conduct multi-physics field coupling analysis on dry-type transformers, accurately calculate the distribution characteristics of electromagnetic fields, temperature fields, and flow fields of dry-type transformers, and explore the influence of forced convection heat transfer on the cooling effect of transformers, it will be of great value to the safe operation of dry-type transformers. In order to meet the growing demand for fast calculation and real-time evaluation of hot spot temperatures of dry-type transformers, it is urgent to simplify the multi-physics field coupling model based on thermoelectric analogy theory, finely construct the thermal circuit model of dry-type transformers, and optimize the thermal circuit model parameters through the multi-physics field coupling calculation results, and carry out dry-type transformer temperature rise modeling research.

[0006] When a dry-type transformer is in operation, the internal iron core, coils, and metal components will all produce losses, and the load changes will cause the transformer losses to change accordingly. All these losses will cause the dry-type transformer to heat up and the temperature to rise. Excessive temperature will reduce the efficiency of the transformer and shorten the life of the transformer. From the above analysis, it can be seen that the transformer cooling system plays a decisive role in whether the transformer can work normally. The utilization rate of the fluid domain in the box of the traditional dry-type transformer air cooling system is low, which causes the transformer temperature to rise and malfunction, reducing the reliability of the transformer. Therefore, it is urgent to provide a forced air cooling structure for the potted end of the dry-type transformer winding.

[0007] Purpose of the Invention

[0008] The present invention provides a forced air cooling structure for the potted end of a dry-type transformer winding, so as to solve the problem that the dry-type transformer in the prior art usually adopts a closed design, the internal space is relatively closed, and the heat dissipation surface area is limited, resulting in lower heat dissipation efficiency than that of an open transformer. This may cause a temperature rise problem during long-term operation or high load.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A new cooling system using epoxy resin potting technology for high and low voltage windings. First, the epoxy resin potting of high and low voltage windings adopts a rectangular slot structure to increase the axial ventilation and heat dissipation area. In order to solve the problem of excessive temperature rise at the end of the winding in the forced ventilation cooling system, a multi-heat pipe parallel cooling structure is adopted to increase the heat dissipation area at the end of the winding. Secondly, by rationally designing the air flow path, the air is fully utilized to take away the heat. The heat dissipation area and air utilization rate are increased to improve the heat dissipation efficiency of the winding. The high-voltage outer end insulation cylinder is designed to force air to flow through the outside of the high-voltage epoxy resin potting cylinder, and the size of the insulation cylinder is increased to make it 10mm away from the core window, so that a large amount of air flows through the upper end of the core to reduce the problem of local overheating of the core. At the same time, the mechanical structure of the transformer is optimized, which helps to reduce the vibration or deformation problems that the transformer may encounter during use and enhance the durability and safety of the equipment.

[0011] To achieve the above object, the present invention provides the following technical solutions:

[0012] A strong wind-cooled dry transformer winding potting structure, characterized in that it includes a transformer box, a transformer three-phase cylinder, an iron core, an upper iron core clamp, a lower iron core clamp, a lower wind shield and a heat pipe heat dissipation assembly, wherein a plurality of transformer three-phase cylinders are provided, and each transformer three-phase cylinder is arranged around the iron core;

[0013] The iron core is arranged in the transformer box through an upper iron core clamp and a lower iron core clamp;

[0014] The lower wind shield is fixedly arranged in the transformer box, and the lower wind shield divides the transformer box into an upper air outlet and a lower air supply. The lower air supply is provided with an air inlet, and the lower wind shield is sleeved on the outer wall of the three-phase cylinder of the transformer;

[0015] The upper air supply portion of the transformer box is provided with a plurality of air outlets;

[0016] A plurality of ventilation channels are provided in the epoxy potting cylinder of the high-voltage winding of the three-phase cylinder of the transformer along the axial direction;

[0017] The heat pipe heat dissipation component is arranged on the top of the low-voltage winding epoxy potting cylinder and the high-voltage winding epoxy potting cylinder of the transformer three-phase cylinder.

[0018] As a further description of the above scheme, the core upper clamp includes a fixing plate and a first connecting bolt, two fixing plates are provided, and the two fixing plates are arranged in parallel, and both ends of the fixing plate are fixedly arranged inside the transformer box; the two fixing plates are connected by the first connecting bolt, and when the core is installed, the two fixing plates of the core upper clamp are fixed to the upper part of the core by the first connecting bolt;

[0019] The structure of the lower core clamp is the same as that of the upper core clamp. The lower core clamp includes a fixing plate and a second connecting bolt. Two fixing plates are provided and the two fixing plates are arranged in parallel. Both ends of the fixing plates are fixed inside the transformer box. The two fixing plates are connected by the second connecting bolts. When the core is installed, the two fixing plates of the lower core clamp are fixed to the lower part of the core by the second connecting bolts.

[0020] As a further description of the above scheme, the heat pipe heat dissipation assembly includes a heat pipe, a heat pipe heat sink and heat dissipation ribs, the heat pipe includes a heat absorption section and a heat dissipation section; the heat pipe heat sink is arranged in the heat dissipation section of the heat pipe, the heat pipe heat sink includes a plurality of blades, and the blades are arranged on the heat pipe heat sink at intervals; the heat dissipation rib is obliquely arranged on the heat absorption section of the heat pipe, and the other end of the heat dissipation rib extends into the epoxy resin potting glue of the low-voltage winding epoxy potting tube or the high-voltage winding epoxy potting tube.

[0021] As a further description of the above scheme, the lower wind shield is provided with a hole matching the three-phase cylinder of the transformer, and the three-phase cylinder of the transformer is respectively composed of a low-voltage winding epoxy potting cylinder, a low-voltage winding insulation cylinder, a high-voltage winding insulation cylinder, a high-voltage winding epoxy potting cylinder and a high-voltage outer insulation cylinder from the inside to the outside, and the lower part of the high-voltage outer insulation cylinder is fixedly connected to the inner wall of the hole of the lower wind shield; a plurality of through ventilation channels are spaced apart in the high-voltage winding epoxy potting cylinder, and the ventilation channels are arranged along the height direction of the high-voltage winding epoxy potting cylinder, and the high-voltage winding epoxy potting cylinder is provided with a plurality of through ventilation channels. The outer wall and the inner wall of the epoxy potting cylinder are both provided with first protrusions at intervals along the circumferential direction, the first protrusions are arranged along the height direction of the high-voltage winding epoxy potting cylinder, and every two adjacent first protrusions form a first ventilation groove; the inner wall and the outer wall of the low-voltage winding epoxy potting cylinder are both provided with a plurality of second protrusions at intervals along the circumferential direction, the second protrusions are arranged along the height direction of the low-voltage winding epoxy potting cylinder, and every two adjacent second protrusions form a second ventilation groove; the cross-sectional shapes of the second protrusions and the first protrusions are rectangular, sawtooth, trapezoidal, semicircular or parabolic.

[0022] As a further description of the above scheme, the above-mentioned strong wind cooling dry transformer winding potting structure also includes an upper end pressing block and a lower end pressing block, wherein a plurality of the upper end pressing blocks are provided, and each of the upper end pressing blocks includes a pressing block body and a rib plate, and a card slot is provided at the bottom of the pressing block body, and the pressing block body is engaged with the top of the low-voltage winding insulation cylinder or the high-voltage winding insulation cylinder through the card slot; the rib plate is fixedly arranged on the pressing block body by bolts, and the rib plate is fixedly connected to the fixing plate of the clamp on the iron core;

[0023] There are multiple lower end pressure blocks, each of which includes a pressure block body and a rib plate. A slot is provided on the top of the pressure block body, and the pressure block body is snap-fitted with the top of the low-voltage winding insulation cylinder or the high-voltage winding insulation cylinder through the slot; the rib plate is fixed to the body by bolts, and the rib plate is fixedly connected to the fixing plate of the lower clamp of the iron core.

[0024] As a further description of the above scheme, a windshield base is provided at the bottom of the high and low voltage winding insulation cylinder; a card slot matching the insulating windshield is provided at the top of the lower end pressure block, and the lower end pressure block is snap-fitted with the insulating windshield.

[0025] As a further description of the above scheme, the above-mentioned strong wind cooling dry type transformer winding potting structure also includes an upper shunt wind shield, one end of the upper shunt wind shield is fixedly arranged inside the transformer box, the other end of the upper shunt wind shield is abutted against the side wall of the fixed plate of the iron core upper clamp, and the upper shunt wind shield is located above the lower wind shield; the plurality of air outlets include an upper air outlet and a lower air outlet, and the upper air outlet and the lower air outlet are symmetrically arranged above and below the upper shunt wind shield, and the bottom height of the lower air outlet is higher than the top height of the three-phase cylinder of the transformer.

[0026] As a further description of the above scheme, when the transformer box is cooled, the path of the cooling air is: the first air path is discharged from the box through the high-voltage outer insulating cylinder and the high-voltage winding epoxy potting cylinder; the second air path takes away the temperature generated by the operation of the high-voltage winding through the high-voltage winding epoxy resin ventilation duct; the third air path is discharged from the box through the high-voltage winding epoxy potting cylinder and the low-voltage winding epoxy potting cylinder; the fourth air path is discharged from the box through the gap between the inner side of the low-voltage winding epoxy potting cylinder and the outer surface of the iron core, and the gap between the low-voltage winding insulating cylinder, the high-voltage winding insulating cylinder and the high-voltage winding epoxy potting cylinder to exclude the box; the third air path is discharged from the box through the gap between the low-voltage winding epoxy potting cylinder and the low-voltage winding insulating cylinder and the high-voltage winding insulating cylinder; the fourth air path is discharged from the box through the gap between the low-voltage winding epoxy potting cylinder and the outer surface of the iron core.

[0027] Advantages and effects of the present invention:

[0028] The box-type air-cooled transformer designed this time has designed a working principle of three fans to extract air to realize the fluid domain of strong wind, and added upper and lower wind shields to improve the heat dissipation efficiency; designed a bottom insulating wind shield so that the wind can all flow through the high and low voltage winding epoxy resin potting tube and the iron core to reduce the temperature of the iron core and winding; at the same time, the shape of the high and low voltage winding potting glue is changed to increase the heat dissipation area and effectively reduce the temperature of the high and low voltage windings. Adding high and low voltage winding epoxy resin tube heat pipes has excellent thermal conductivity and can efficiently transfer heat. Compared with traditional heat dissipation methods, heat pipes can transfer heat from the heat source to the radiator or cooling system more quickly, improving the efficiency of thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a strong wind-cooled dry-type transformer winding potting structure according to an embodiment of the present invention;

[0030] Figure 2 A top view of an epoxy resin potting cylinder for a high voltage winding according to an embodiment of the present invention;

[0031] Figure 3 A three-dimensional diagram of a high voltage winding epoxy resin potting cylinder according to an embodiment of the present invention;

[0032] Figure 4 A top view of a low voltage winding epoxy resin potting cylinder according to an embodiment of the present invention;

[0033] Figure 5 A three-dimensional diagram of a low voltage winding epoxy resin potting cylinder according to an embodiment of the present invention;

[0034] Figure 6 A three-dimensional simulated winding temperature rise diagram of a transformer according to an embodiment of the present invention;

[0035] Figure 7 A schematic diagram of the operation of a heat pipe according to an embodiment of the present invention;

[0036] Figure 8 This is a working principle diagram of a heat pipe according to an embodiment of the present invention;

[0037] Fig. 9 The heat pipe of the embodiment of the present invention only considers the influence of the contact gap of the heat absorbing section or the heat releasing section on the equivalent thermal conductivity;

[0038] Fig.10 This is a curve of an embodiment of the present invention that takes into account the influence of the contact gap between the heat absorbing section and the heat releasing section of the heat pipe on the equivalent thermal conductivity;

[0039] Fig.11 It is a heat pipe assembly diagram of an embodiment of the present invention;

[0040] Fig.12 A three-dimensional diagram of a heat pipe assembly according to an embodiment of the present invention;

[0041] Fig.13 The three-dimensional simulated core temperature of the transformer according to an embodiment of the present invention;

[0042] Fig.14 It is an assembly diagram of the upper end pressing block of an embodiment of the present invention;

[0043] Fig.15 It is an assembly diagram of the lower end pressing block of an embodiment of the present invention;

[0044] Fig.16 It is an assembly diagram of a single-phase insulating cylinder according to an embodiment of the present invention;

[0045] Fig.17 It is an assembly diagram of the upper end pressing block of an embodiment of the present invention;

[0046] Fig.18 It is an assembly diagram of the core of an embodiment of the present invention;

[0047] Fig.19 A partial diagram of the assembly of a clamp according to an embodiment of the present invention;

[0048] Fig. 20 An exploded view of the insulation group of an embodiment of the present invention;

[0049] Fig.21 A diagram of a windshield base according to an embodiment of the present invention;

[0050] Fig. 22 A cross-sectional view of a windshield plate at the upper end of an insulating cylinder according to an embodiment of the present invention;

[0051] Fig.23 It is a box assembly diagram of an embodiment of the present invention;

[0052] Fig.24 Schematic diagram of single-phase two-dimensional wind flow according to an embodiment of the present invention.

[0053] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0054] 1. Iron core upper clamp, 2. Iron core lower clamp, 3. Upper shunt windshield, 4. Lower windshield, 5. Insulation windshield, 6. Upper end pressure block, 7. Lower end pressure block, 8. Rib, 9. Iron core, 10. High voltage winding outer insulation cylinder, 11. High voltage winding insulation cylinder, 12. Low voltage winding epoxy resin potting cylinder, 13. High voltage winding epoxy resin potting cylinder, 14. Windshield fixing, 15. Nut, 16. Gasket, 17. First connecting bolt, 18. Second connecting bolt, 1 9. Transformer box, 20. Air outlet, 23. Lower air inlet, 24. Epoxy resin axial ventilation slot, 25. High-voltage winding epoxy resin ventilation duct A, 26. High-voltage winding epoxy resin ventilation duct B, 27. High-voltage winding epoxy resin ventilation duct C, 28. Heat pipe, 29. Heat pipe heat sink, 30 axial epoxy resin ventilation duct A, 31 axial epoxy resin ventilation duct B, 32 axial epoxy resin ventilation duct C, 33. Air, 34. Heat dissipation ribs, 35. Wind shield at the upper end of the insulating tube. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] like Figure 1-Figure 16 As shown, a strong wind-cooled dry transformer winding potting structure includes a transformer box 19, a transformer three-phase cylinder, an iron core, an upper iron core clamp 1, a lower iron core clamp 2, and a lower wind shield 4, wherein a plurality of transformer three-phase cylinders are provided, wherein an air inlet 23 is provided at the lower air supply portion, and each transformer three-phase cylinder is arranged around the iron core;

[0057] The iron core 9 is arranged in the transformer box 19 through the iron core upper clamp 1 and the iron core lower clamp 2;

[0058] The lower windshield 4 is fixedly arranged in the transformer box 19, wherein the lower windshield 4 divides the transformer box 19 into an upper air outlet and a lower air supply, and the lower windshield is sleeved on the outer wall of the transformer three-phase cylinder; wherein the upper air supply part of the transformer box 19 is provided with a plurality of air outlets; wherein the high-voltage winding epoxy potting cylinder of the transformer three-phase cylinder is provided with a plurality of ventilation channels along the axial direction. This design adds an upper end heat pipe: an efficient heat conduction device that uses the phase change process (evaporation and condensation) of a liquid to transfer heat. It is usually composed of a sealed metal pipe, which is filled with a working fluid (usually a liquid medium). The function of the heat pipe is to quickly and evenly transfer the heat generated at the upper end to the air, so as to achieve the purpose of thermal management and thermal control, and solve the problems such as local overheating at the upper end; secondly, the high-voltage external insulation and the box air outlet position are designed: a high-voltage external insulation cylinder is added, the size of the insulation cylinder is changed to make it exceed the epoxy resin potting cylinder, and the position of the box air outlet is changed. This design can improve the airflow distribution inside the box, ensure that the cooling air effectively flows through the upper end of the core, thereby reducing the temperature rise of the core; secondly, design the winding potting form: by changing the shape of the winding, the strength of the winding can be increased, and the heating area can be increased, thereby improving the heat dissipation performance of the transformer. This change helps to suppress the temperature rise of the winding, effectively reduce the operating temperature of the transformer, and improve the reliability and service life of the equipment; in addition, design epoxy resin axial ventilation grooves: epoxy resin axial ventilation grooves are selected in the appearance design. This shape not only improves heat dissipation, but also reduces the use of potting materials, thereby achieving economic and environmental protection effects.

[0059] The core upper clamp 1 of the embodiment of the present invention includes a fixing plate and a first connecting bolt 17, wherein two fixing plates are provided, and the two fixing plates are arranged in parallel, and both ends of the fixing plates are fixedly arranged inside the transformer box 19; the two fixing plates are connected by the first connecting bolt 17, and when the core is installed, the two fixing plates of the core upper clamp 1 are fixed to the upper part of the core 9 by the first connecting bolt 17;

[0060] The structure of the lower core clamp 2 is the same as that of the upper core clamp 1. The lower core clamp 2 includes a fixing plate and a second connecting bolt 18. Two fixing plates are provided, and the two fixing plates are arranged in parallel. Both ends of the fixing plates are fixed inside the transformer box 19. The two fixing plates are connected by the second connecting bolts 18. When the core 9 is installed, the two fixing plates of the lower core clamp 2 are fixed to the lower part of the core 9 by the second connecting bolts 18.

[0061] The heat pipe heat dissipation assembly of the present invention includes a heat pipe 28, a heat pipe heat sink and heat dissipation ribs, wherein the heat pipe 28 includes a heat absorption section and a heat dissipation section; the heat pipe heat sink is arranged in the heat dissipation section of the heat pipe 28, and the heat pipe heat sink includes a plurality of blades, and the blades are arranged on the heat pipe heat sink at intervals; the heat dissipation rib is obliquely arranged on the heat absorption section of the heat pipe 28, and the other end of the heat dissipation rib extends into the epoxy resin potting glue of the low-voltage winding epoxy potting tube 12 or the high-voltage winding epoxy potting tube 13.

[0062] like Figure 7 As shown in FIG. 1 , the temperature rise of the upper end of the transformer is relatively high from the three-dimensional simulation winding temperature rise diagram. There may be defects in the design or manufacturing process of the transformer, such as improper material selection, manufacturing process problems, etc., which lead to uneven heat distribution or local overheating in some parts of the top. Adding heat pipe 28 can solve the above problems. Adding heat pipe structure such as Fig.10 The connection between the heat pipe 28 and the heat pipe fin 29 is welding. According to the heat transfer process of the heat pipe, the axial direction can be divided into three sections, namely the heat absorption section, the heat exchange section and the heat release section. The radial direction can be divided into three layers, namely the shell, the wick structure and the steam chamber. Figure 7 As shown in Figure 2, heat transfer in a heat pipe can be described by three processes. Heat is first absorbed in the heat absorption section, then transferred through the adiabatic section, and finally discharged by the cooling medium in the heat release section.

[0063] Working principle Figure 8 As shown, the heat absorbing section of the heat pipe is in contact with the heat source, and the heat flow is transferred to the heat pipe shell through the contact thermal resistance R between the heat source and the heat pipe shell. The radial thermal resistance of the heat absorbing section is R 1a The contact thermal resistance R between the heat sink and the heat pipe shell 1b The radial thermal resistance of the heat absorbing section is R 2a The radial thermal resistance of the heat pipe shell in the heat release section is R 2b The radial thermal resistance of the heat absorbing cross-section candle wick structure is R 3a The radial thermal resistance of the candle wick structure in the heat release section is R 3b。 The liquid working medium evaporates into gas working medium in the heat absorption section. The radial thermal resistance is R 4a The gaseous working medium condenses into liquid working medium in the heat release section, and the radial thermal resistance is R 4b. The axial heat transfer resistance of the heat pipe shell is R5. The axial thermal resistance of the wick structure is R6. The axial heat transfer resistance of the gas working fluid is R7. The working medium of the heat pipe should have the characteristics of high latent heat of vaporization, high thermal conductivity, large surface tension, low viscosity and good wettability. Deionized water is a commonly used working fluid for heat pipes. In addition, ethanol and acetone are often used as heat pipe working fluids, but there is a certain gap between their latent heat and the thermal conductivity of vaporized water and deionized water. The contact thermal resistance between the heat source and the shell. The heat absorption section of the heat pipe is located in the high and low pressure epoxy resin potting grooves. Due to the processing technology, the diameter of the heat pipe is smaller than the diameter of the heat source, forming an air gap, so that a contact thermal resistance with a thickness of d1 is formed between the heat pipe and the heat source.

[0064]

[0065] Where D1 is the outer diameter of the heat pipe, λ air is the thermal conductivity of air, L2 is the length of the heat pipe heat absorption section, that is, the length of the part in contact with the heat source. The radial thermal resistance of the heat absorption section shell is similar to the contact thermal resistance. The radial thermal resistance R 2a It can be expressed as:

[0066]

[0067] Where D2 is the inner diameter of the heat pipe shell, λ1 is the thermal conductivity of the heat pipe shell, and L2 is the length of the heat pipe heat absorption section. The radial thermal resistance of the wick structure. The radial thermal resistance is similar to the contact thermal resistance, R 3a The radial thermal resistance of the candle wick structure can be expressed as:

[0068]

[0069] Where D3 is the inner diameter of the wick structure, and λ2 is the thermal conductivity of the wick structure, which can be calculated by referring to the commonly used parallel equivalent thermal conductivity model of the wick structure. Since the working temperature of the heat pipe is stable, the physical parameters of the liquid do not change much with temperature. Therefore, the effect of temperature on the equivalent thermal conductivity of the wick structure is ignored. Thermal resistance of evaporation of liquid working fluid. The heated liquid working fluid in the heat pipe begins to evaporate and become gas, so there is a heat transfer process at the gas-liquid interface. According to the molecular motion theory, the thermal resistance of heat transfer can be expressed as.

[0070]

[0071] In the formula, R V is the gas constant of the gaseous working fluid, T V is the steam temperature, Q r is the latent heat of vaporization of the working fluid, p V is the gas pressure.

[0072] Since the shell of the heat pipe is thin and is generally made of materials with high thermal conductivity such as copper or aluminum, the temperature difference between the steam and the shell is small, generally less than 0.5°C. Therefore, the shell temperature is taken as the steam temperature T V .

[0073] R v =R / m

[0074] Where R is the universal constant of gas, R = 8.314 J / (K·mol), m is the molar mass of gas, and .Axial thermal resistance of heat pipe shell. The heat source heat absorbed by the heat pipe heat absorption section is partially transferred through the vaporization heat absorption process, and partially transferred through the axial direction of the heat pipe shell. Therefore, according to the definition of thermal resistance, the thermal resistance R5 of axial heat transfer of heat pipe shell is:

[0075]

[0076] Where L1 is the total length of the heat pipe and L3 is the length of the heat release section. Axial thermal resistance of the wick structure. The axial thermal resistance of the wick structure is similar to the axial thermal resistance of the shell. The axial thermal resistance of the wick structure can be expressed as R6:

[0077]

[0078] Gas working fluid liquefaction thermal resistance. The gas working fluid flows toward the heat release section under the action of internal pressure. According to fluid mechanics theory [, the thermal resistance generated by the axial flow of gas can be expressed as R7:

[0079]

[0080] p v =ρ v R v T v

[0081] In the formula, μ v is the viscosity coefficient of steam working fluid, ρ v is the gas working fluid density. Considering the symmetry of the heat network, we only need to make the lengths of the heat absorption section and the heat release section different to get R 1b ~R 4b At the same time, since evaporation and liquefaction are reversible, the thermal resistance of condensation and vaporization is the same. When the length of the heat absorption section and the heat release section is the same (i.e. L2 = L3), R 1a =R 1b ,R 2a =R 2b ,R 3a =R 3b ,R 4a =R 4b The total heat resistance of the heat pipe can be expressed as R All :

[0082]

[0083] In order to simplify the heat transfer process of the heat pipe, the heat pipe is equivalent to a solid with large thermal conductivity and isotropy. Assume that the equivalent thermal conductivity of the heat pipe is λ eq , to ensure that the thermal resistance of the heat pipe before and after the equivalent remains unchanged. The equivalent thermal conductivity coefficient can be expressed as λ eq :

[0084]

[0085] S eq =π(D1 / 2 ) 2

[0086]

[0087] Where Req is the equivalent thermal resistance of the heat pipe, Leq and Seq are the equivalent transfer length and heat transfer area of ​​the heat pipe, respectively.

[0088] When two different solids are in contact with each other, contact thermal resistance will be generated. Studies have found that the contact thermal resistance between the heat absorption section and the heat release section has a great influence on the equivalent thermal conductivity of the heat pipe. Therefore, the variation law of the equivalent thermal conductivity with the contact gap at one end of the heat pipe and the contact gap at both ends is considered respectively. This paper considers the influence of the contact gap size and the thermal conductivity of the material in the contact gap on the equivalent thermal conductivity of the heat pipe. For example, the outer diameter D1 is 10mm, the length L1 is 300mm, the length of the heat absorption section and the heat release section L2 and L3 is 150mm, the shell thickness is 1mm, and the core structure thickness is 0.5mm.

[0089] Fig.10 The curve showing the effect of the contact gap on the equivalent thermal conductivity considering only the heat absorption section or the heat release section is shown, where 0.0204W / (m·K) is the thermal conductivity of air. As the contact gap increases, the equivalent thermal conductivity of the heat pipe gradually decreases, and the contact thermal resistance has a great influence on the thermal conductivity. When the contact gap reaches 0.1mm, the equivalent thermal conductivity of the heat pipe is only 1818W / (m·K). The effect of fillers with different thermal conductivities in the contact gap on the heat pipe is analyzed. When the thermal conductivity in the contact gap increases from 0.0204 to 0.1, 0.5 and 1.0W / (m·K), the equivalent thermal conductivity of the heat pipe can reach 7203, 17004 and 20676W / (m·K).

[0090] Fig.11It is shown that the contact gaps of the heat absorbing section and the heat releasing section of the heat pipe 28 are taken into account at the same time. Similarly, taking a contact gap of 0.1 mm as an example, when the thermal conductivity of the contact gap increases from 0.0204 to 0.1, 0.5 and 1.0 W / (m·K), the equivalent thermal conductivity of the heat pipe can reach 4051, 12547 and 17014 W / (m·K). It can be seen that the contact thermal resistance and thermal conductivity of the filler have a more serious impact on the equivalent thermal conductivity of the heat pipe. Therefore, in practical applications, the influence of the heat pipe contact resistance on the cooling performance can be reduced by filling the contact gap with thermally conductive glue.

[0091] Fig.12The heat pipe and heat pipe fin assembly two-dimensional diagram. The heat pipe 28 is in the shape of a long rectangle, with a length of 12mm, a width of 3mm and a height of 450mm. The heat pipe is divided into a heat absorption section and a heat dissipation section, wherein the heat absorption section is located at the lower end and has a length of 300mm; the heat dissipation section is located at the upper end and has a length of 150mm. Heat pipe fins 29 are arranged on both sides of the heat dissipation section at the upper end of the heat pipe, the purpose of which is to increase the heat dissipation capacity. Each heat sink has 9 blades, the length of the blade is 4.5mm, the width is 0.7mm, the height is 150mm, and the interval between the blades is 0.7mm. At one end of the heat absorption section, there are 3 rows and 19 columns, a total of 57 heat absorption ribs 34 with a diameter of 1.3mm and a length of 3mm, which are 45° to the vertical direction. These heat dissipation ribs penetrate into the epoxy resin potting glue, which can better contact with the epoxy resin potting cylinder, thereby improving the heat absorption efficiency of the heat absorption section. Between the heat pipe heat absorption section and the heat dissipation section, a rounded structure with a length of 6mm and a radius of 5mm is provided. Heat pipe fins are installed on both sides of the heat dissipation section. However, due to the presence of the epoxy resin potting cylinder, only one side of the heat pipe fin has wind flowing through it, and the other side does not have a lot of wind passing through, thereby reducing the heat dissipation effect of the heat pipe. The designed rounded structure effectively solves the problem of no wind flowing through the heat pipe fin on one side, greatly improving the heat dissipation performance of the heat pipe; at the same time, the insulating material in the transformer is very sensitive to temperature. Through effective heat pipe design, the operating temperature of the internal components of the transformer can be reduced, the service life of the insulating material can be extended, and the insulation aging and damage caused by overheating can be reduced; secondly, the heat pipe can help maintain the appropriate operating temperature range of the transformer oil, which is one of the key factors to maintain the normal operation of the transformer and improve its efficiency. Through effective heat pipe design, the stable operating temperature of the transformer can be maintained under different load conditions; thirdly, the heat pipe design and thermal management of the present invention can enable the transformer to carry a higher load at the same size and increase its rated capacity. This technical optimization can improve the power density and performance of the equipment without increasing the size of the equipment; finally, the heat pipe helps to achieve heat balance inside and outside the transformer. By effectively transferring heat to the external environment or cooling system, the operating temperature of the transformer can be better controlled to ensure that it operates within the design range. This is very important for long-term stable operation and extending the life of the equipment.

[0092] The lower windshield plate 4 of the embodiment of the present invention is provided with a hole matching the three-phase cylinder of the transformer, wherein the three-phase cylinder of the transformer is respectively a low-voltage winding epoxy potting cylinder 12, a low-voltage winding insulation cylinder, a high-voltage winding insulation cylinder 11, a high-voltage winding epoxy potting cylinder 13 and a high-voltage outer insulation cylinder 10 from the inside to the outside, and the lower part of the high-voltage outer insulation cylinder 10 is fixedly connected to the inner wall of the hole of the lower windshield plate 4; a plurality of through ventilation channels are spaced apart in the high-voltage winding epoxy potting cylinder 13, and the ventilation channels are arranged along the height direction of the high-voltage winding epoxy potting cylinder 13, and in the high-voltage The outer wall and the inner wall of the winding epoxy potting cylinder 13 are both provided with first protrusions at intervals along the circumferential direction, the first protrusions are arranged along the height direction of the high-voltage winding epoxy potting cylinder 13, and every two adjacent first protrusions form a first ventilation groove; the inner wall and the outer wall of the low-voltage winding epoxy potting cylinder 12 are both provided with a plurality of second protrusions at intervals along the circumferential direction, the second protrusions are arranged along the height direction of the low-voltage winding epoxy potting cylinder 12, and every two adjacent second protrusions form a second ventilation groove; the cross-sectional shapes of the second protrusions and the first protrusions are rectangular, sawtooth, trapezoidal, semicircular or parabolic. The high-voltage winding epoxy potting tube 13 and the low-voltage winding epoxy potting tube 12 of the present design are respectively provided with a plurality of first ventilation grooves and a second ventilation groove on the inner wall and the outer wall thereof. This shape increases the heat dissipation area of ​​the high-voltage winding epoxy potting tube 13 and the low-voltage winding epoxy potting tube 12, so that the cooling effect is better. At the same time, a plurality of through ventilation channels are spaced apart inside the high-voltage winding epoxy potting tube 13, and cooling air can also be introduced into the high-voltage winding epoxy potting tube 13, so that the cooling effect is better, and the amount of potting material used is also reduced.

[0093] The strong wind-cooled dry transformer winding potting structure of the embodiment of the present invention further includes an upper end pressing block and a lower end pressing block, wherein a plurality of upper end pressing blocks are provided, each upper end pressing block includes a pressing block body and a rib plate, wherein a card slot is provided at the bottom of the pressing block body, and the card slot is engaged with the top of the high and low voltage winding insulation cylinder; wherein the rib plate is fixedly arranged on the pressing block body by bolts, and the rib plate is fixedly connected to the fixing plate of the clamp on the iron core;

[0094] The embodiment of the present invention has multiple lower end pressing blocks, each of which includes a pressing block body and a rib plate, wherein a slot is provided on the top of the pressing block body, wherein the slot is engaged with the bottom of the high and low voltage winding insulation cylinder; wherein the rib plate is fixedly arranged on the body by bolts, and the rib plate is fixedly connected to the fixing plate of the lower clamp of the core. This design can improve the strength of the overall transformer three-phase cylinder through the upper and lower pressing blocks, and these structural improvement measures help reduce the vibration or deformation problems that the transformer may encounter during use, and enhance the durability and safety of the equipment.

[0095] The bottom of the high and low voltage winding insulation cylinder of the embodiment of the present invention is provided with a windshield base; wherein the top of the lower end pressing block is provided with a slot matching the insulating windshield plate, and the lower end pressing block is snap-fitted with the insulating windshield plate.

[0096] The top of the low-voltage winding insulation cylinder and the high-voltage winding insulation cylinder 11 of the embodiment of the present invention are provided with an insulation cylinder upper windshield 35; wherein the bottom of the upper end pressing block 6 is provided with a card slot matching the insulation cylinder upper windshield 35, and the upper end pressing block 6 is engaged with the insulation cylinder upper windshield 35. In order to effectively solve the problem of overheating of the upper end of the winding potting cylinder, we can focus on increasing the speed of air flowing through its upper end to enhance the heat dissipation efficiency. When the air flow rate is accelerated, the heat generated by the upper end of the winding potting cylinder can be taken away more quickly, just like a turbulent water flow can take away floating objects faster. In this way, the overheating condition of the upper end can be significantly improved, ensuring the stable operation of the equipment, reducing the risk of failure due to overheating, and extending the service life of the equipment.

[0097] The strong wind cooling dry transformer winding potting structure of the embodiment of the present invention also includes an upper shunt wind shield, wherein one end of the upper shunt wind shield is fixedly arranged inside the transformer box 19 through a wind shield fixing member 14, and the other end of the upper shunt wind shield is abutted against the side wall of the fixing plate of the iron core upper clamp, and the upper shunt wind shield is located above the lower wind shield; a plurality of air outlets include an upper air outlet 20 and a lower air outlet 21, wherein the upper air outlet 20 and the lower air outlet 21 are symmetrically arranged above and below the upper shunt wind shield 3, and the bottom height of the lower air outlet 21 is higher than the top height of the three-phase cylinder of the transformer.

[0098] When the transformer box 19 of the embodiment of the present invention is cooled, the path of the cooling air is as follows: the first air path is discharged from the box through the gap between the high-voltage outer insulating cylinder 10 and the high-voltage winding epoxy potting cylinder 13; the second air path is taken away from the box through the high-voltage winding epoxy resin ventilation duct 26; the third air path is discharged from the box through the gap between the high-voltage winding epoxy potting cylinder 13 and the low-voltage winding epoxy potting cylinder 12; the fourth air path is discharged from the box through the gap between the inner side of the low-voltage winding epoxy potting cylinder 12 and the outer surface of the iron core 9, and the gap between the low-voltage winding insulating cylinder, the high-voltage winding insulating cylinder 11 and the high-voltage winding epoxy potting cylinder 13; the third air path is discharged from the box through the gap between the low-voltage winding epoxy potting cylinder 12 and the low-voltage winding insulating cylinder and the high-voltage winding insulating cylinder 11; the fourth air path is discharged from the box through the gap between the low-voltage winding epoxy potting cylinder 12 and the outer surface of the iron core. This design takes into account the low heat dissipation efficiency of the wind power transformer itself and adopts measures to add exhaust fans. This measure can increase wind speed and air utilization, effectively reduce the temperature rise of the core 9 and windings, and improve the overall heat dissipation effect. At the same time, by designing an insulating windshield base, a sealed space is formed, which improves the air utilization and further reduces the temperature rise of the core 9 and windings. This measure helps to optimize the heat dissipation structure and improve the working efficiency and stability of the transformer; in addition, an upper shunt windshield 3 and a lower windshield 4 and a main insulating cylinder windshield base 5 are introduced. The air flow in the traditional dry-type transformer box 19 is chaotic, slow and interferes with each other. These designs improve the flow direction of the air domain in the box (see Fig.14 ), so that the air forms a closed loop to improve the utilization rate of air and continuously and effectively reduce the temperature.

[0099] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A strong wind-cooled dry transformer winding potting structure, characterized in that: It comprises a transformer box (19), a transformer three-phase cylinder, an iron core (9), an iron core upper clamp (1), an iron core lower clamp (2), a lower wind shield (4) and a heat pipe heat dissipation assembly. The transformer three-phase cylinder is provided in plurality, and each transformer three-phase cylinder is arranged around the iron core; The iron core (9) is arranged in a transformer box (19) via an upper iron core clamp (1) and a lower iron core clamp (2); The lower wind shield (4) is fixedly arranged in the transformer box (19), and the lower wind shield (4) divides the transformer box (19) into an upper air outlet portion and a lower air supply portion, the lower air supply portion is provided with an air inlet (23), and the lower air supply portion and the lower wind shield are sleeved on the outer wall of the transformer three-phase cylinder; The upper air supply portion of the transformer box (19) is provided with a plurality of air outlets; A plurality of ventilation channels are provided in the high-voltage winding epoxy potting cylinder (13) of the three-phase cylinder of the transformer along the axial direction; The heat pipe heat dissipation assembly is arranged on the top of the low-voltage winding epoxy potting cylinder (12) and the high-voltage winding epoxy potting cylinder (13) of the three-phase cylinder of the transformer.

2. The strong wind cooling dry transformer winding potting structure according to claim 1 is characterized in that: The core upper clamp (1) comprises a fixing plate and a first connecting bolt (17), two fixing plates are provided, and the two fixing plates are arranged in parallel, and both ends of the fixing plates are fixedly arranged inside the transformer box (19); the two fixing plates are connected by the first connecting bolt (17), and when the core is installed, the two fixing plates of the core upper clamp (1) are fixed to the upper part of the core (9) by the first connecting bolt (17); The iron core lower clamp (2) has the same structure as the iron core upper clamp (1), and comprises a fixing plate and a second connecting bolt (18). Two fixing plates are provided, and the two fixing plates are arranged in parallel. Both ends of the fixing plates are fixedly arranged inside the transformer box (19); the two fixing plates are connected by the second connecting bolt (18). When the iron core (9) is installed, the two fixing plates of the iron core lower clamp (2) are fixed to the lower part of the iron core (9) by the second connecting bolt (18).

3. The strong wind cooling dry type transformer winding potting structure according to claim 2 is characterized in that: The heat pipe heat dissipation assembly comprises a heat pipe (28), a heat pipe heat sink and a heat dissipation rib, wherein the heat pipe (28) comprises a heat absorption section and a heat dissipation section; the heat pipe heat sink is arranged at the heat dissipation section of the heat pipe (28), the heat pipe heat sink comprises a plurality of blades, and the blades are arranged on the heat pipe heat sink at intervals; the heat dissipation rib is arranged obliquely on the heat absorption section of the heat pipe (28), and the other end of the heat dissipation rib extends into the epoxy resin potting glue of the low-voltage winding epoxy potting cylinder (12) or the high-voltage winding epoxy potting cylinder (13).

4. The strong wind cooling dry transformer winding potting structure according to claim 2 is characterized in that: The lower windshield (4) is provided with a hole matching the three-phase tube of the transformer. The three-phase tube of the transformer comprises, from the inside to the outside, a low-voltage winding epoxy potting tube (12), a low-voltage winding insulation tube, a high-voltage winding insulation tube (11), a high-voltage winding epoxy potting tube (13) and a high-voltage outer insulation tube (10). The lower part of the high-voltage outer insulation tube (10) is fixedly connected to the inner wall of the hole of the lower windshield (4). A plurality of through ventilation channels are arranged at intervals in the high-voltage winding epoxy potting tube (13). The ventilation channels are arranged along the height direction of the high-voltage winding epoxy potting tube (13). The outer wall and the inner wall of the high-voltage winding epoxy potting cylinder (13) are both provided with first protrusions at intervals along the circumferential direction, the first protrusions are provided along the height direction of the high-voltage winding epoxy potting cylinder (13), and every two adjacent first protrusions form a first ventilation groove; the inner wall and the outer wall of the low-voltage winding epoxy potting cylinder (12) are both provided with a plurality of second protrusions at intervals along the circumferential direction, the second protrusions are provided along the height direction of the low-voltage winding epoxy potting cylinder (12), and every two adjacent second protrusions form a second ventilation groove; the cross-sectional shapes of the second protrusions and the first protrusions are rectangular, sawtooth, trapezoidal, semicircular or parabolic.

5. The strong wind cooling dry transformer winding potting structure according to claim 2 is characterized in that: The tops of the low-voltage winding insulation cylinder and the high-voltage winding insulation cylinder (11) are provided with insulation cylinder upper end windshields (35); wherein the bottom of the upper end pressing block (6) is provided with a clamping groove matching the insulation cylinder upper end windshield (35), and the upper end pressing block (6) is clamped and matched with the insulation cylinder upper end windshield (35).

6. The strong wind cooling dry transformer winding potting structure according to claim 3 is characterized by: It also includes an upper pressure block (6) and a lower pressure block (7), wherein a plurality of upper pressure blocks (6) are provided, each of the upper pressure blocks (6) includes a pressure block body and a rib plate (8), a slot is provided at the bottom of the pressure block body, and the pressure block body is engaged with the top of the low-voltage winding insulation cylinder or the high-voltage winding insulation cylinder (11) through the slot; the rib plate (8) is fixedly arranged on the pressure block body by bolts, and the rib plate (8) is fixedly connected to the fixing plate of the core upper clamp (1); A plurality of lower end pressing blocks (7) are provided, each of which comprises a pressing block body and a rib plate (8). A slot is provided on the top of the pressing block body, and the pressing block body is snap-fitted with the top of the low-voltage winding insulation cylinder or the high-voltage winding insulation cylinder (11) through the slot. The rib plate (8) is fixedly arranged on the body by bolts, and the rib plate (8) is fixedly connected to the fixing plate of the lower core clamp (2).

7. The strong wind cooling dry transformer winding potting structure according to claim 4 is characterized in that: A windshield base (5) is provided at the bottom of the high and low voltage winding insulation cylinder; a slot matching the insulating windshield (5) is provided at the top of the lower end pressing block (7), and the lower end pressing block is snap-fitted with the insulating windshield (5).

8. The strong wind cooling dry transformer winding potting structure according to claim 4 is characterized in that: It also includes an upper shunt wind shield (3), one end of which is fixedly arranged inside the transformer box (19), and the other end of which is in contact with the side wall of the fixing plate of the core upper clamp (1), and the upper shunt wind shield (3) is located above the lower wind shield 4; the bottom height of a plurality of the air outlets (20) is higher than the top height of the transformer three-phase barrel.

9. The strong wind cooling dry transformer winding potting structure according to claim 4 is characterized in that: When the transformer box (19) is cooled, the cooling air has the following paths: the first air path is discharged from the box through the space between the high-voltage outer insulating cylinder (10) and the high-voltage winding epoxy potting cylinder (13); the second air path is discharged from the box through the high-voltage winding epoxy resin ventilation duct (26) to remove the temperature generated by the high-voltage winding during operation; the third air path is discharged from the box through the space between the high-voltage winding epoxy potting cylinder (13) and the low-voltage winding epoxy potting cylinder (12); the fourth air path is discharged from the box through the space between the low-voltage winding epoxy potting cylinder (13) and the high-voltage winding epoxy potting cylinder (12); The box is discharged through the gap between the inner side of the sealing tube (12) and the outer surface of the iron core (9), and the gap between the low-voltage winding insulation tube, the high-voltage winding insulation tube (11) and the high-voltage winding epoxy potting tube (13). The third air path is discharged through the gap between the low-voltage winding epoxy potting tube (12) and the low-voltage winding insulation tube and the high-voltage winding insulation tube (11). The box is discharged through the gap between the low-voltage winding epoxy potting tube (12) and the outer surface of the iron core.

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