An oil-immersed distribution transformer

Abstract

The application belongs to the technical field of oil-immersed transformers, and particularly relates to an oil-immersed distribution transformer, which comprises upper and lower anti-impact units arranged at the axial two ends of a winding unit and used for decomposing and buffering the axial impact force of the winding unit. The upper anti-impact unit comprises an upper axial force decomposition unit arranged between the winding unit and an upper clamp and configured to convert the axial displacement of the winding unit into horizontal displacement. The axial impact force of the winding unit is converted into at least part of horizontal component force through the sliding of upper moving wedge blocks relative to upper static wedge blocks along first and second inclined surfaces. The variable stiffness composite support cylinder arranged between the iron core and the winding unit and the axial force decomposition and buffering structure arranged at the axial two ends of the winding unit can absorb and disperse impact energy through the change of material properties in extreme conditions such as sudden short circuit, and improve the safety and stability of the oil-immersed distribution transformer.

Description

Technical Field

[0001] This invention belongs to the technical field of oil-immersed transformers, and specifically relates to an oil-immersed distribution transformer. Background Technology

[0002] Oil-immersed distribution transformers are widely used in medium and low voltage power distribution networks. Their core and windings are completely submerged in insulating transformer oil, which serves as both the primary insulating and cooling medium. During operation, oil-immersed distribution transformers inevitably encounter various short-circuit faults. When a sudden short circuit occurs on the transformer's output side, a huge short-circuit current flows through the windings, generating electromagnetic forces several times, or even tens of times, greater than those during normal operation. These electromagnetic forces include radial forces that cause the windings to expand or contract radially, and axial forces that cause the windings to compress or stretch axially.

[0003] Problems with existing technology:

[0004] 1. Existing oil-immersed distribution transformers have an insulating cylinder between the winding and the core, or a hard pressure plate at the end of the winding. This structure has sufficient rigidity under steady state, but at the moment of sudden short circuit, the radial impact force is much greater than the structural bearing limit, which can easily cause the insulating cylinder to crack, the support bar to break, or the winding to become unstable and collapse.

[0005] 2. Although some oil-immersed distribution transformers are designed to absorb shocks using elastic materials, under normal operating conditions, the rigidity of the soft materials is insufficient, which makes it impossible to maintain the precise position of the windings, easily leading to vibration displacement and affecting long-term operational reliability.

[0006] 3. Currently, existing technologies mainly rely on the rigid support of end pressure plates or the buffering of elastic pads to deal with axial impact forces. There is a lack of effective structures to convert the axial force into a different direction before dissipating it, resulting in most of the impact energy still being transferred to the clamps and oil tank, causing damage. Summary of the Invention

[0007] The purpose of this invention is to provide an oil-immersed distribution transformer that, by setting a variable stiffness composite support cylinder between the core and the winding, and setting an axial force decomposition and buffer structure at both ends of the winding, can absorb and disperse impact energy through changes in material properties under extreme conditions such as sudden short circuits, thereby improving the safety and stability of the oil-immersed distribution transformer.

[0008] The specific technical solution adopted by this invention is as follows:

[0009] An oil-immersed distribution transformer includes an upper shock-resistant unit and a lower shock-resistant unit disposed at both axial ends of a winding unit. The upper and lower shock-resistant units are used to decompose and buffer the axial impact force of the winding unit. The upper shock-resistant unit includes:

[0010] An upper axial force decomposition unit, disposed between the winding unit and the upper clamp, is configured to convert the axial displacement of the winding unit into a horizontal displacement, including:

[0011] The upper moving wedge is fixedly installed at the bottom of the upper clamp and has a first inclined surface that slopes downward; the upper stationary wedge is fixed at the axial top end of the winding unit and has a second inclined surface that fits against the first inclined surface and slopes upward.

[0012] A first axial damping ring is disposed at the bottom of the upper clamp. The first axial damping ring has a cavity filled with damping oil inside, and a throttling component is disposed inside the cavity.

[0013] The axial impact force of the winding unit is converted into a horizontal component by the sliding of the upper moving wedge relative to the upper stationary wedge along the first and second inclined surfaces. This component is then transmitted to the first axial damping ring through the contact protrusion, driving the inner side of the first axial damping ring to deform radially, causing the damping oil to flow through the throttling assembly and generate a damping force.

[0014] The top of the first axial damping ring is fixedly installed to the upper clamp via a hanger, so that the upper clamp pushes the upper axial force decomposition unit to move vertically through the first axial damping ring, and the bottom of the upper axial force decomposition unit abuts against the top of the winding unit.

[0015] The first axial damping ring includes a housing fixedly connected to the bottom of the lifting component, and the inner side of the housing abuts against the side of the upper axial force decomposition unit through an elastic sleeve.

[0016] The throttling component is fixedly installed inside the cavity and divides the cavity into a first oil chamber and a second oil chamber, wherein the volume of the first oil chamber is greater than the volume of the second oil chamber.

[0017] The first oil chamber is located between the elastic sleeve and the throttling assembly, and the second oil chamber is located between the throttling assembly and the outer shell.

[0018] The throttling component has a first through hole on the side near the elastic sleeve and a second through hole on the side near the outer shell. The first through hole and the second through hole are connected through a first flow channel, so that the damping oil flows inside the first oil chamber and the second oil chamber.

[0019] The diameter of the first through hole is larger than that of the second through hole, causing the damping oil inside the first oil cavity to flow into the second oil cavity and generate damping force.

[0020] The top of the upper stationary wedge is fixedly installed to the upper clamping member by a fixing member, and the upper clamping member is fixedly installed to the lower clamping member by a clamping screw, so that the fixing member pushes the upper moving wedge to move vertically through the upper stationary wedge and moves the upper moving wedge to the top of the winding unit;

[0021] The axial impact force of the winding unit pushes the insulating contact plate to drive the upper moving wedge block to move vertically. Through the sliding cooperation between the upper stationary wedge block and the upper moving wedge block, the upper moving wedge block moves horizontally on the top of the insulating contact plate, and the contact protrusion installed on one side of the upper moving wedge block squeezes the first axial damping ring.

[0022] The second inclined surface of the upper stationary wedge is provided with an installation groove, and the surface of the first inclined surface of the upper movable wedge is integrally provided with a limiting slide block. The limiting slide block passes through the installation groove and is slidably installed with the guide rod.

[0023] The upper moving wedge block drives the limiting slide to slide inside the mounting groove, and the limiting slide pushes the reset spring to compress.

[0024] The upper anti-impact unit is used to disperse and buffer the upward axial impact force of the winding unit, and the lower anti-impact unit is used to disperse and buffer the downward axial impact force of the winding unit. The winding unit and the lower anti-impact unit are arranged symmetrically.

[0025] The lower impact-resistant unit includes a lower stationary wedge block fixedly installed on the top of the lower clamping member, and a second axial damping ring fixedly installed on the top of the lower stationary wedge block. The second axial damping ring has the same structure as the first axial damping ring, and the lower moving wedge block has the same structure as the upper moving wedge block.

[0026] The winding unit includes a support cylinder sleeved outside the iron core, a low-voltage winding is wound on the surface of the support cylinder, an isolation sleeve is sleeved outside the low-voltage winding, and a high-voltage winding is wound outside the isolation sleeve.

[0027] The isolation sleeve includes an insulating partition, and multiple support bars are integrally provided on both sides of the isolation sleeve. A second flow channel for insulating oil is provided between the support bars and the low-voltage winding, and a second flow channel for insulating oil is provided between the support bars and the high-voltage winding.

[0028] The support cylinder comprises an inner layer, a middle layer, and an outer layer from the inside out. The inner layer is in contact with the iron core, and the outer layer is in contact with the low-voltage winding.

[0029] The intermediate layer is a honeycomb-like microstructure layer composed of regular hexagons, used to fill shear-thickening liquid.

[0030] A method for decomposing and buffering axial impact force in an oil-immersed distribution transformer includes the following steps:

[0031] Receiving axial impact force: When a transformer experiences a short-circuit fault, the winding unit is subjected to an axial impact force along its axis, which is transmitted to the upper and lower moving wedges connected to the ends of the winding unit.

[0032] Inclined plane decomposition and direction conversion: Under the action of axial impact force, the upper moving wedge and the lower moving wedge slide along the second inclined plane of the upper stationary wedge and the lower stationary wedge that cooperate with the first inclined plane, decomposing the axial impact force into a component force along the inclined plane direction and a normal force perpendicular to the inclined plane, while converting at least a part of the axial impact force into a component force in the horizontal direction.

[0033] Horizontal force transmission: The horizontal component of the force is transmitted through the contact protrusion to the first axial damping ring disposed between the upper clamp and the winding unit;

[0034] Hydraulic damping energy dissipation: The first axial damping ring undergoes radial deformation under the action of horizontal force, and the volume of its internal cavity changes, forcing the damping oil filled in the cavity to flow between the first oil chamber and the second oil chamber through the hole on the throttling assembly, and generating damping force, which converts the impact energy into heat energy and dissipates it.

[0035] Elastic reset: After the impact, the elastic sleeve of the first axial damping ring returns to its original shape by its own elastic restoring force, and at the same time pushes the contact protrusion, the upper moving wedge, the lower moving wedge and the winding unit to reset to the initial position.

[0036] The technical effects achieved by this invention are as follows:

[0037] This invention employs a shear-thickening liquid filled in a honeycomb-like middle layer structure. Under normal operating conditions, the shear-thickening liquid is in a low-viscosity fluid state, making the support cylinder flexible, facilitating winding assembly without adding extra stress. However, during a short circuit, the windings experience high-speed radial impact, causing the shear-thickening liquid to solidify instantly, increasing the stiffness of the support cylinder and effectively absorbing the radial impact energy generated by the winding units, thereby limiting winding deformation. Through the special design of the support cylinder, it achieves an adaptive support effect compared to existing rigid supports, effectively solving the problem that traditional support structures cannot simultaneously achieve steady-state stiffness and transient impact resistance.

[0038] This invention, through the sliding engagement of the upper moving wedge and the upper stationary wedge, and the sliding engagement of the lower moving wedge and the lower stationary wedge, enables the winding unit to decompose the upward axial impact force into a horizontal component through the sliding engagement of the first inclined surface and the second inclined surface. This component is then transmitted to the elastic sleeve via the contact protrusion, causing the elastic sleeve to contract towards the interior of the cavity and push the damping oil inside the first oil cavity to flow through the throttling assembly to the interior of the second oil cavity. Throttling is achieved through the cooperation of the first through hole, the second through hole, and the first flow channel of the throttling assembly, and the impact energy is converted into heat energy for dissipation. This effectively reduces the direct transmission of the axial impact force caused by the winding unit's circuit break to the upper clamp, the lower clamp, and the oil tank, while also preventing end insulation compression deformation and structural damage.

[0039] This invention employs an elliptical ring structure similar to the winding unit and the core, and achieves multi-point coordinated force distribution through multiple upper axial force decomposition units and lower moving wedges that are uniformly abutted along the circumference. This ensures that short-circuit impacts can be effectively absorbed regardless of how they are distributed along the circumference of the winding unit. Furthermore, the throttling components can be flexibly adapted to meet the short-circuit protection requirements of transformers with different capacities and voltage levels by replacing them with throttling components of different diameters and numbers of holes, as well as damping oil of different viscosities. Attached Figure Description

[0040] Figure 1 This is a perspective view of the overall installation structure of the present invention;

[0041] Figure 2 This is a schematic diagram of the internal structure of the fuel tank in this invention;

[0042] Figure 3 This is a schematic diagram of the main structure of the transformer in this invention;

[0043] Figure 4 This is a schematic diagram of the upper impact-resistant unit structure in this invention;

[0044] Figure 5 This is a schematic diagram of the upper axial force decomposition unit structure in this invention;

[0045] Figure 6 This is a schematic diagram of the cross-sectional structure of the upper axial force decomposition unit in this invention;

[0046] Figure 7 This is a schematic diagram of the cross-sectional structure of the first axial damping ring in this invention;

[0047] Figure 8 This is an enlarged cross-sectional schematic diagram of the throttling component in this invention;

[0048] Figure 9 This is a schematic diagram of the lower impact-resistant unit structure in this invention;

[0049] Figure 10This is a schematic diagram of the installation structure of the lower moving wedge and the lower stationary wedge in this invention;

[0050] Figure 11 This is a schematic diagram of the cross-sectional structure of the winding unit in this invention;

[0051] Figure 12 This is the present invention. Figure 11 Enlarged schematic diagram of the structure at point A in the middle;

[0052] Figure 13 This is a schematic diagram of the cross-sectional structure of the support cylinder in this invention;

[0053] Figure 14 This is a flowchart of the method for decomposing and buffering the axial impact force of an oil-immersed distribution transformer in this invention.

[0054] The attached diagram lists the components represented by each number as follows:

[0055] 1. Oil tank; 2. Cooling unit; 3. Cooling fan; 4. Oil conservator; 5. Iron core; 6. Upper clamp;

[0056] 7. Upper impact-resistant unit; 71. First axial damping ring;

[0057] 711. Outer shell; 712. Elastic sleeve; 713. Throttling assembly; 7131. First through hole; 7132. Second through hole; 7133. First flow channel; 7134. Guide cone; 714. First oil chamber; 715. Second oil chamber; 716. Cavity;

[0058] 72. Lifting components;

[0059] 73. Upper axial force decomposition unit; 731. Upper moving wedge; 732. Contact protrusion; 733. Upper stationary wedge; 734. First inclined surface; 735. Second inclined surface; 736. Limiting slide; 737. Return spring; 738. Guide rod; 739. Insulating contact plate;

[0060] 74. Fasteners; 75. Limiting baffles;

[0061] 8. Winding unit; 81. Support cylinder; 811. Inner layer; 812. Intermediate layer; 813. Outer layer; 82. Low-voltage winding; 83. Isolation sleeve; 831. Insulating partition; 832. Support bar; 833. Second flow channel; 84. High-voltage winding;

[0062] 9. Lower impact-resistant unit; 91. Second axial damping ring; 92. Lower moving wedge; 93. Lower stationary wedge; 94. Mounting groove;

[0063] 10. Lower clamp; 11. Base frame; 12. Clamping screw. Detailed Implementation

[0064] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0065] like Figure 1-14 As shown, an oil-immersed distribution transformer includes an oil tank 1. An oil conservator 4 is installed on the top of the oil tank 1 to replenish the insulating oil inside the oil tank 1. At the same time, heat dissipation units 2 are connected to both sides of the oil tank 1 for heat dissipation of the insulating oil inside the oil tank 1. A cooling fan 4 is also installed at the bottom of the heat dissipation unit to improve the heat dissipation efficiency of the insulating oil.

[0066] According to the above structure, a lower clamp 10 is fixedly installed inside the oil tank 1 via a bottom frame 11. An upper clamp 6 is fixedly installed on the top of the lower clamp 10 via a clamping screw 12. An iron core 5 is installed between the upper clamp 6 and the lower clamp 10. Furthermore, a winding unit 8 is sleeved on the outside of the iron core 5. An upper anti-impact unit 7 and a lower anti-impact unit 9 are respectively provided at the top and bottom of the winding unit 8 for dispersing and buffering axial impact forces. Furthermore, the upper anti-impact unit 7 is fixedly installed with the upper clamp 6, and the lower anti-impact unit 9 is fixedly installed with the lower clamp 10. Therefore, during the process of installing and fixing the upper clamp 6 and the lower clamp 10 via the clamping screw 12, the upper anti-impact unit 7 and the lower anti-impact unit 9 can be fixed at the top and bottom of the winding unit 8 respectively, so that the upward or downward impact force generated by the winding unit 8 when the circuit is broken can be dispersed and buffered.

[0067] It should be noted that three sets of winding units 8 are provided between the upper clamp 6 and the lower clamp 10, and the upper anti-impact unit 7 and the lower anti-impact unit 9 are arranged corresponding to the three sets of winding units 8 to ensure that when each set of winding units 8 generates axial impact force, the axial impact force can be effectively decomposed and buffered through the corresponding upper anti-impact unit 7 and lower anti-impact unit 9.

[0068] See attached document Figures 3 to 7 The upper impact-resistant unit 7 includes a first axial damping ring 71 disposed between the winding unit 8 and the upper clamp 6. The first axial damping ring 71 is fixedly installed to the upper clamp 6 by a hanger 72, which consists of a nut and a screw. The bottom end of the screw is welded to the top of the first axial damping ring 71, and the top of the screw passes through the upper clamp 6 and is installed to the upper clamp 6 by a nut.

[0069] According to the above structure, both the first axial damping ring 71 and the winding unit 8 are elliptical ring structures, and the first axial damping ring 71 is slightly larger than the winding unit 8. The first axial damping ring 71 with its ring structure can surround the end of the winding unit 8, ensuring that axial impact forces at different points can be dispersed and buffered.

[0070] To achieve the above objectives, multiple upper axial force decomposition units 73 are arranged axially along the inner side of the first axial damping ring 71 inside the first axial damping ring 71. The upper stationary wedges 733 of the multiple upper axial force decomposition units 73 are fixedly installed to the upper clamping member 6 through the fixing member 74. At the same time, the upper moving wedges 731 of the multiple upper axial force decomposition units 73 are abutted against the top of the winding unit 8 through the insulating contact plate 739. With the arrangement of the upper axial force decomposition units 73, under the action of axial impact force, the upper moving wedges 731 can slide along the inclined surface of the upper stationary wedges 733, converting the vertical impact force into a horizontal component force.

[0071] Specifically, the upper moving wedge 731 and the upper stationary wedge 733 can form a winding unit 8. When the circuit is broken, the axial displacement caused by the axial impact force is converted into a horizontal displacement, which is achieved through the precise cooperation between the first inclined surface 734 and the second inclined surface 735, ensuring that the impact force can be effectively decomposed in multiple directions.

[0072] More specifically, the contact protrusion 732 acts as a transmission component, transmitting the horizontal component force to the surface of the elastic sleeve 712 of the first axial damping ring 71. Since the cavity 716 inside the first axial damping ring 71 is filled with damping oil (methyl silicone oil, viscosity 5000 cSt), the elastic sleeve 712 will undergo radial contraction when subjected to external force, pushing the damping oil to flow between the first oil cavity 714 and the second oil cavity 715.

[0073] It should be noted that this flow process is controlled by the throttling component 713. The difference in diameter between the first through hole 7131 and the second through hole 7132 creates a significant throttling effect. The throttling effect can provide a certain damping force, thereby achieving buffering after the axial impact force is dispersed, reducing the direct impact of the axial impact force on the upper clamp 6 and the lower clamp 10.

[0074] See attached document Figure 4 , Figure 7 and Figure 8 Four sets of first flow channels 7133 are arranged in a ring array inside the first through hole 7131, corresponding to the second through hole 7132. The first through hole 7131 is also equipped with a guide cone 7134 for guiding the damping oil to ensure that the damping oil can be evenly distributed and form a stable throttling effect during the flow process.

[0075] According to the above structure, the first through hole 7131 is connected to the four sets of second through holes 7132 through four sets of first flow channels 7133, so the damping material located inside the first oil cavity 714 can be smoothly guided to the inside of the second oil cavity 715.

[0076] Specifically, the second oil chamber 715 is located between the housing 711 and the throttling assembly 713. The housing 711 is made of PEEK engineering plastic and surface metallization processing, which gives the first axial damping ring 71 good impact resistance, while ensuring excellent corrosion resistance and wear resistance during long-term operation.

[0077] In addition, the setting of the throttling component 713 can not only effectively control the flow path of the damping oil, but also achieve efficient dissipation of impact energy through the optimization of the internal structure of the throttling component 713. Specifically, when the damping oil passes through the throttling component of the throttling component 713, its flow velocity is restricted due to the narrow design of the flow channel and the guiding effect of the guide cone, thereby generating significant hydraulic resistance.

[0078] Based on the above, the energy of the axial impact force can be converted into heat energy through hydraulic resistance and dissipated into the insulating oil through the surface of the housing 711, thereby preventing the energy from being directly transferred to the key components of the transformer. In addition, the first through hole 7131 and the second through hole 7132 in the throttling component 713 can be adjusted according to actual needs. For example, by replacing the throttling components 713 with different diameters or numbers, or by using damping oil of different viscosities, the short-circuit withstand requirements of transformers with different capacities and voltage levels can be adapted.

[0079] See attached document Figure 3 and Figures 6 to 8 To ensure that the axial impact force generated by the short circuit of the winding unit 8 can be stably and reliably dispersed and buffered by the upper anti-impact unit 7 and the lower anti-impact unit 9, an installation groove can be provided on the surface of the upper stationary wedge 733 to form a sliding fit with the limiting slide 736. The installation groove can limit the movement trajectory of the upper moving wedge 731.

[0080] Furthermore, the compression and reset of the return spring 737 can provide additional buffering effect. Therefore, when the short circuit of the winding unit 8 ends and the axial impact force stops, the elastic action of the return spring 737 can push the limit slide 736 to drive the upper moving wedge 731 to reset in preparation for the next axial impact. Furthermore, a guide rod 738 is also installed in the mounting groove of the upper stationary wedge 733. The guide rod 738 can ensure the accurate positioning of the upper moving wedge 731 during the movement process and avoid deviation or jamming.

[0081] It is worth noting that a groove is also provided at the bottom of the upper moving wedge 731, and a guide rail can be installed inside the groove so that the insulating contact plate 739 can slide with the upper moving wedge 731. Therefore, when converting part of the axial impact force of the winding unit 8 into a horizontal component force, the setting of the insulating contact plate 739 can prevent the upper axial force decomposition unit 73 from pulling on the end of the winding unit 8.

[0082] It should be noted that the first inclined surface 734 set at the top of the upper moving wedge 731 has an angle of 15°-30° with the horizontal plane. The angle design can ensure that the axial impact force has high efficiency in the decomposition process, while avoiding the problems of insufficient energy transfer or excessive structural load caused by the angle being too large or too small.

[0083] As can be further explained, the first inclined surface 734 of the upper moving wedge 731 and the second inclined surface 735 of the upper stationary wedge 733 can form a sliding pair, and the surface of the second inclined surface 735 is also coated with a polytetrafluoroethylene self-lubricating coating with a friction coefficient of 0.08, which is used to ensure that there will be no jamming between the upper moving wedge 731 and the upper stationary wedge 733.

[0084] See attached document Figures 3 to 6 To further improve the reliability of dispersion and buffering, an arc design can be adopted on the contact surface between the insulating contact plate 739 and the winding unit 8 to expand the contact area, disperse local pressure, and avoid insulation damage caused by stress concentration.

[0085] Meanwhile, the insulating contact plate 739 is made of epoxy resin composite material with excellent electrical insulation properties. Its dielectric constant is 4.5 and its breakdown voltage is greater than 20kV / mm, which fully meets the insulation requirements of the distribution transformer.

[0086] In terms of assembly process, the 73 series upper axial force decomposition unit can also adopt a modular design concept. The components are quickly assembled through precision machining, so that the performance of each 73 upper axial force decomposition unit is highly consistent. In particular, it can significantly improve production efficiency in the large-scale production of oil-immersed distribution transformers.

[0087] In addition, a limiting baffle 75 is integrally formed on one side of the upper moving wedge 731 of the upper axial force decomposition unit 73. The limiting baffle 75 is also made of epoxy resin composite material with excellent electrical insulation properties. At the same time, the setting of the limiting baffle 75 can provide a side clamping effect for the winding unit 8 when the winding unit 8 does not have an open circuit causing axial impact, thereby improving the stability of the winding unit 8. Furthermore, when the winding unit 8 has a short circuit and radial impact occurs, the radial displacement of the winding unit 8 can also be limited by the limiting baffle 75, thereby ensuring that the winding unit 8 will not become unstable and collapse.

[0088] See attached document Figure 3 , Figure 4 , Figure 7 and Figure 8 The elastic sleeve 712 is arranged axially along the inner side of the outer shell 711 to seal the cavity 716. The elastic sleeve 712 is made of nitrile rubber (Shore hardness 70A). The elastic properties of the elastic sleeve 712 enable it to quickly return to its original shape after the external force disappears, thereby assisting the resetting of the upper axial force decomposition unit 73.

[0089] Specifically, the reset mechanism of the elastic sleeve 712 not only ensures the stability of the entire dispersion and buffer structure after multiple impacts, but also effectively extends the service life of the equipment. At the same time, the use of the elastic sleeve 712 with a Shore hardness of 70A ensures sufficient elastic deformation capacity while maintaining the necessary structural strength.

[0090] See attached document Figures 3 to 6 , Figure 9 and Figure 10 The structural design of the upper impact-resistant unit 7 and the lower impact-resistant unit 9 not only achieves effective decomposition and buffering of axial impact force, but also improves the overall impact resistance through multi-point synergistic force bearing. Specifically, the upper axial force decomposition unit 73 and the lower moving wedge block 92 are evenly distributed along the circumference of the winding unit 8 and form a stable connection with the end of the winding unit 8 through multiple contact points. No matter how the short-circuit impact force is distributed in the circumferential direction, it can be quickly absorbed and dispersed into the entire structure, avoiding damage caused by local stress concentration.

[0091] It is worth noting that in practical applications, the installation position and angle of the upper anti-impact unit 7 and the lower anti-impact unit 9 can be adjusted according to the specific design requirements of the transformer. For example, by changing the initial gap between the upper moving wedge 731 and the upper stationary wedge 733, or by adjusting the mating depth between the lower moving wedge 92 and the lower stationary wedge 93, the short-circuit protection requirements of transformers of different specifications can be flexibly adapted.

[0092] In addition, to further optimize the energy dissipation effect, the flow path of the damping oil inside the first axial damping ring 71 has been precisely calculated and simulated to ensure that the best throttling effect can be achieved under different operating conditions. Especially under high energy impact conditions, the hydraulic resistance generated when the damping oil passes through the narrow flow channel of the throttling component 713 will increase significantly, thereby converting more impact energy into heat energy and dissipating it quickly, avoiding damage to the key components of the transformer.

[0093] See attached document Figure 3 , Figure 9 and Figure 10The lower impact-resistant unit 9 and the winding unit 8 are arranged symmetrically. The lower stationary wedge 93 of the lower impact-resistant unit 9 is fixedly installed on the top of the lower clamp 10 by bolts. The top of the lower stationary wedge 93 is also fixedly installed with a second axial damping ring 91. The second axial damping ring 91 has the same structure as the first axial damping ring 71. The lower moving wedge 92 has the same structure as the upper moving wedge 731. This ensures that the upward or downward axial impact force dispersion and buffering effect are consistent, further improving the overall stability and reliability.

[0094] Furthermore, through the symmetrical design of the upper anti-impact unit 7 and the lower anti-impact unit 9, it can not only effectively cope with the bidirectional axial impact force generated by the winding unit when the circuit is broken, but also achieve uniform energy dissipation under different working conditions, avoiding structural failure caused by uneven local stress.

[0095] In addition, the second axial damping ring 91 is also equipped with a throttling component and damping oil flow path that match the first axial damping ring 71. Its specific structure and working principle are the same as those of the first axial damping ring 71, but in actual assembly, it can be configured differently according to the transformer capacity and voltage level.

[0096] To ensure installation accuracy and operational reliability, the sliding mating surfaces between the lower moving wedge 92 and the lower stationary wedge 93 are precision machined and coated with the same polytetrafluoroethylene self-lubricating coating as the second inclined surface 735 to reduce the coefficient of friction and improve durability.

[0097] Meanwhile, the bottom of the lower moving wedge 92 is also provided with an insulating layer that contacts the end of the winding unit 8. This insulating layer is made of high polymer composite material, which has excellent electrical insulation performance and mechanical strength, and can effectively prevent partial discharge phenomena that may be caused during the transmission of short-circuit impact force.

[0098] See attached document Figure 3 and Figures 11 to 13 A support cylinder 81 is provided between the winding unit 8 and the iron core 5. A low-voltage winding 82 is wound around the surface of the support cylinder 81. An isolation sleeve 83 is sleeved on the outside of the low-voltage winding 82. A high-voltage winding 84 is wound around the outside of the isolation sleeve 83. Therefore, a complete transformer winding can be formed by the support cylinder 81, the low-voltage winding 82, the isolation sleeve 83, and the high-voltage winding 84.

[0099] According to the above structure, the support cylinder 81 includes an inner layer 811, a middle layer 812 and an outer layer 813 from the inside to the outside. The inner layer 811 is in contact with the iron core 5 and the outer layer 813 is in contact with the low voltage winding 82.

[0100] Specifically, the inner layer 811 is made of glass fiber reinforced epoxy resin composite material with a thickness of 2mm and a tensile modulus of 25GPa. Through the direct contact between the inner layer 811 and the iron core 5, it can provide basic radial stiffness under normal operating conditions and ensure the concentricity between the winding unit 8 and the iron core 5.

[0101] More specifically, the outer layer 813 is made of polytetrafluoroethylene (PTFE) with a thickness of 0.5 mm and is in direct contact with the inner surface of the low-voltage winding 82. The low friction characteristics of PTFE ensure that the winding unit 8 can slide freely during thermal expansion or short-circuit impact, thus avoiding the generation of additional stress.

[0102] It is worth noting that the intermediate layer 812 is a honeycomb microstructure injection molded from polyetheretherketone (PEEK). The honeycomb microstructure is a regular hexagon with a unit side length of 3 mm and a wall thickness of 0.3 mm. The interior of each honeycomb unit is filled with a shear-thickening liquid and encapsulated by a flexible polyimide film.

[0103] According to the inner cylinder described above, the shear thickening liquid is a silica nanoparticle / polyethylene glycol dispersion system, with a silica nanoparticle mass fraction of 30% and a particle size of 200nm. This ensures that when a sudden short circuit occurs in the winding unit 8, the winding unit 8 is subjected to a huge radial electromagnetic force, instantly generating a high-speed radial displacement. The shear thickening liquid can solidify instantly, and the stiffness of the intermediate layer 812 increases sharply. Working in synergy with the inner layer 811, it provides impact resistance tens of times greater than normal, effectively limiting the radial deformation of the winding unit 8.

[0104] like Figure 1-14 As shown, this embodiment also provides a method for decomposing and buffering the axial impact force of an oil-immersed distribution transformer, which achieves the decomposition and buffering of the axial impact force of the transformer under short-circuit conditions through the following specific structure;

[0105] When a sudden short circuit occurs, winding unit 8 is subjected to an upward axial impact force. The winding unit 8 drives the upper moving wedge 731 to move upward. The first inclined surface 734 of the upper moving wedge 731 slides along the second inclined surface 735 of the upper stationary wedge 733. According to the principle of force decomposition, the relationship between the axial impact force and the horizontal component force satisfies: ;

[0106] in, The component of the force in the horizontal direction, Axial impact force, It is the angle between the inclined plane and the horizontal plane.

[0107] Specifically, axial impact force ;

[0108] in, The component of the force along the inclined plane, It is the normal force perpendicular to the inclined plane.

[0109] More specifically, the component of force in the horizontal direction ;

[0110] In a specific implementation, the horizontal component of the force... The upper moving wedge 731 is pushed to move horizontally, and the upper moving wedge 731 drives the contact protrusion 732 to move horizontally, and the contact protrusion 732 presses against the inner wall of the first axial damping ring 71.

[0111] When the elastic sleeve 712 of the first axial damping ring 71 is subjected to a horizontal thrust, the first axial damping ring 71 undergoes radial compression at that point. Since the first axial damping ring 71 is a continuous ring structure, the local compression causes the volume of the cavity 716 at that point to decrease. The damping oil is forced to flow from the first oil cavity 714 to the second oil cavity 715 (or in the opposite direction) through the throttling assembly 713. When the damping oil flows through the throttling assembly 713, it generates a damping force, which converts the impact energy (mechanical energy) into heat energy and dissipates it.

[0112] After the impact ends, the elastic sleeve 712 returns to its original shape by its own elastic restoring force, and the damping oil flows back to the initial position through the throttling component 713. At the same time, it pushes the contact protrusion 732, the upper moving wedge 731 and the winding unit 8 to reset to the initial position. Meanwhile, the cooperation structure of the lower moving wedge 92 and the lower stationary wedge 93 is symmetrical with the above process. When the axial impact force is downward, the lower moving wedge 92 and the lower stationary wedge 93 cooperate to complete the decomposition and dissipation of the force.

[0113] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. An oil-immersed distribution transformer, characterized in that, include: An upper anti-impact unit (7) and a lower anti-impact unit (9) are disposed at both ends of the winding unit (8) along the axial direction. The upper anti-impact unit (7) and the lower anti-impact unit (9) are used to decompose and buffer the axial impact force of the winding unit (8). The upper anti-impact unit (7) includes: An upper axial force decomposition unit (73), disposed between the winding unit (8) and the upper clamp (6), is configured to convert the axial displacement of the winding unit (8) into a horizontal displacement, including: The upper moving wedge (731) is fixedly installed at the bottom of the upper clamp (6) and has a first inclined surface (734) that slopes downward; the upper stationary wedge (733) is fixed at the axial top end of the winding unit (8) and has a second inclined surface (735) that is in contact with the first inclined surface (734) and slopes upward. A first axial damping ring (71) is disposed at the bottom of the upper clamp (6). The first axial damping ring (71) has a cavity (716) filled with damping oil inside, and a throttling component (713) is disposed inside the cavity (716). The axial impact force of the winding unit (8) is converted into a horizontal component force by the sliding of the upper moving wedge (731) relative to the upper stationary wedge (733) along the first inclined plane (734) and the second inclined plane (735). The component force is then transmitted to the first axial damping ring (71) through the contact protrusion (732), which drives the inner radial deformation of the first axial damping ring (71) so that the damping oil flows through the throttling assembly (713) to generate a damping force.

2. The oil-immersed distribution transformer according to claim 1, characterized in that: The top of the first axial damping ring (71) is fixedly installed with the upper clamp (6) through the hanger (72), so that the upper clamp (6) pushes the upper axial force decomposition unit (73) to move vertically through the first axial damping ring (71), and the bottom of the upper axial force decomposition unit (73) abuts against the top of the winding unit (8). The first axial damping ring (71) includes a housing (711) fixedly connected to the bottom of the lifting member (72), and the inner side of the housing (711) abuts against the side of the upper axial force decomposition unit (73) through an elastic sleeve (712).

3. The oil-immersed distribution transformer according to claim 1, characterized in that: The throttling assembly (713) is fixedly installed inside the cavity (716) and divides the cavity (716) into a first oil chamber (714) and a second oil chamber (715), and the volume of the first oil chamber (714) is greater than the volume of the second oil chamber (715); The first oil chamber (714) is located between the elastic sleeve (712) and the throttling assembly (713), and the second oil chamber (715) is located between the throttling assembly (713) and the outer shell (711).

4. An oil-immersed distribution transformer according to claim 1, characterized in that: The throttling assembly (713) has a first through hole (7131) on the side near the elastic sleeve (712), and a second through hole (7132) on the side near the outer shell (711). The first through hole (7131) and the second through hole (7132) are connected through a first flow channel (7133) to allow damping oil to flow inside the first oil chamber (714) and the second oil chamber (715). The diameter of the first through hole (7131) is larger than that of the second through hole (7132), causing the damping oil inside the first oil cavity (714) to flow into the second oil cavity (715) and generate damping force.

5. An oil-immersed distribution transformer according to claim 1, characterized in that: The top of the upper stationary wedge (733) is fixedly installed with the upper clamp (6) by a fixing member (74), and the upper clamp (6) is fixedly installed with the lower clamp (10) by a clamping screw (12), so that the fixing member (74) pushes the upper moving wedge (731) to move vertically through the upper stationary wedge (733), and causes the upper moving wedge (731) to move toward the top of the winding unit (8); The axial impact force of the winding unit (8) pushes the insulating contact plate (739) to drive the upper moving wedge (731) to move vertically. Through the sliding cooperation between the upper stationary wedge (733) and the upper moving wedge (731), the upper moving wedge (731) moves horizontally at the top of the insulating contact plate (739), and the contact protrusion (732) installed on one side of the upper moving wedge (731) squeezes the first axial damping ring (71).

6. An oil-immersed distribution transformer according to claim 5, characterized in that: The second inclined surface (735) of the upper stationary wedge (733) is provided with an installation groove, and the first inclined surface (734) of the upper moving wedge (731) is integrally provided with a limiting slide (736). The limiting slide (736) passes through the installation groove and is slidably installed with the guide rod (738). The upper moving wedge (731) drives the limiting slide (736) to slide inside the mounting groove, and pushes the return spring (737) to compress through the limiting slide (736).

7. An oil-immersed distribution transformer according to claim 1, characterized in that: The upper anti-impact unit (7) is used to disperse and buffer the upward axial impact force of the winding unit (8), and the lower anti-impact unit (9) is used to disperse and buffer the downward axial impact force of the winding unit (8). The winding unit (8) and the lower anti-impact unit (9) are arranged symmetrically. The lower impact-resistant unit (9) includes a lower stationary wedge (93) fixedly installed on the top of the lower clamp (10), and a second axial damping ring (91) fixedly installed on the top of the lower stationary wedge (93). The second axial damping ring (91) has the same structure as the first axial damping ring (71), and the lower moving wedge (92) has the same structure as the upper moving wedge (731).

8. An oil-immersed distribution transformer according to claim 7, characterized in that: The winding unit (8) includes a support cylinder (81) sleeved on the outside of the iron core (5), a low-voltage winding (82) is wound on the surface of the support cylinder (81), an isolation sleeve (83) is sleeved on the outside of the low-voltage winding (82), and a high-voltage winding (84) is wound on the outside of the isolation sleeve (83). The isolation sleeve (83) includes an insulating partition (831). Multiple support bars (832) are integrally provided on both sides of the isolation sleeve (83). A second flow channel (833) for insulating oil is provided between the support bars (832) and the low-voltage winding (82). A second flow channel (833) for insulating oil is provided between the support bars (832) and the high-voltage winding (84).

9. An oil-immersed distribution transformer according to claim 8, characterized in that: The support cylinder (81) consists of an inner layer (811), a middle layer (812) and an outer layer (813) from the inside to the outside. The inner layer (811) is in contact with the iron core (5) and the outer layer (813) is in contact with the low-voltage winding (82). The intermediate layer (812) is a honeycomb microstructure layer composed of regular hexagons, used to fill shear-thickening liquid.

10. A method for decomposing and buffering axial impact force in an oil-immersed distribution transformer, applied to the oil-immersed distribution transformer according to any one of claims 1-9, characterized in that, Includes the following steps: Receiving axial impact force: When a short circuit fault occurs in the transformer, the winding unit (8) is subjected to an axial impact force along its axis, which is transmitted to the upper moving wedge (731) and the lower moving wedge (92) connected to the end of the winding unit (8). Inclined plane decomposition and direction conversion: Under the action of axial impact force, the upper moving wedge (731) and the lower moving wedge (92) slide along the second inclined plane (735) of the upper stationary wedge (733) and the lower stationary wedge (93) that cooperate with the first inclined plane (734), decomposing the axial impact force into a component force along the inclined plane direction and a normal force perpendicular to the inclined plane, while converting at least a part of the axial impact force into a component force in the horizontal direction; Horizontal force transmission: The horizontal component force is transmitted through the contact protrusion (732) to the first axial damping ring (71) disposed between the upper clamp (6) and the winding unit (8). Hydraulic damping energy dissipation: The first axial damping ring (71) undergoes radial deformation under the action of horizontal force, and the volume of its internal cavity (716) changes, forcing the damping oil filled in the cavity (716) to flow between the first oil cavity (714) and the second oil cavity (715) through the hole on the throttling assembly (713), and generating damping force, which converts the impact energy into heat energy and dissipates it. Elastic reset: After the impact ends, the elastic sleeve (712) of the first axial damping ring (71) returns to its original state by its own elastic restoring force, and at the same time pushes the contact protrusion (732), the upper moving wedge (731), the lower moving wedge (92) and the winding unit (8) back to the initial position.

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