Insulation structure and oil-immersed transformer

Abstract

The utility model discloses an insulation structure and an oil-immersed transformer, which can reduce the cost of insulation materials on a winding and improve the economical efficiency of the transformer by using insulation materials with different insulation grades at different positions of the winding. The insulation structure is arranged on a winding of the oil-immersed transformer and comprises a first insulation structure and a second insulation structure. The first insulation structure is arranged at the first position of the winding, and the first insulation structure is made of insulation materials of B level or above. And the second insulation structure is arranged at a second position of the winding, and the second insulation structure is made of an A-level insulation material.

Description

Technical Field

[0001] The utility model belongs to the technical field of transformer manufacturing, and particularly relates to an insulation structure and an oil-immersed transformer. Background Art

[0002] Insulating materials are usually arranged on the windings in a transformer to ensure the insulation of the windings. The insulation grade of the insulating materials is usually the same as that of the transformer.

[0003] However, during the operation of the transformer, the temperature rise degrees at different positions in the windings are different. In the prior art, for the convenience of material selection and to maintain the reliable insulation of the windings, all insulating materials are usually set to the same insulating material with a relatively high insulation grade, which increases the cost of the insulating materials on the windings and affects the economy of the transformer. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is to provide an insulation structure and an oil-immersed transformer in view of the above deficiencies existing in the prior art. By using insulating materials with different insulation grades at different positions of the windings, the cost of the insulating materials on the windings can be reduced and the economy of the transformer can be improved.

[0005] In a first aspect, an embodiment of the utility model provides an insulation structure. The insulation structure is arranged on the windings of an oil-immersed transformer. The insulation structure includes a first insulation structure and a second insulation structure. The first insulation structure is arranged at a first position of the windings, and the material of the first insulation structure adopts an insulating material of class B or above. The second insulation structure is arranged at a second position of the windings, and the material of the second insulation structure adopts an insulating material of class A.

[0006] In some embodiments, the first insulation structure is used to achieve insulation at the first position of the windings, and the second insulation structure is used to achieve insulation at the second position of the windings. Among them, during the operation of the windings, the temperature at the second position is less than or equal to 105 °C, and the temperature at the first position is greater than 105 °C and less than or equal to 130 °C.

[0007] In some embodiments, the winding is a layer winding, and the layer winding is formed by multiple layers of foil conductors wound from the inside to the outside. The first insulation structure includes interlayer insulation, end insulation, a plurality of first axial braces, and heat-resistant paper. The interlayer insulation is disposed between adjacent layers of foil conductors of the layer winding. The end insulation is disposed at the upper and lower ends of the layer winding. The plurality of first axial braces are fixed between adjacent layers of foil conductors of the layer winding through oil duct sticker paper; an axial oil duct is formed between two adjacent first axial braces. The heat-resistant paper covers the outer side surface of the layer winding. The second insulation structure includes a plurality of second axial braces; the plurality of second axial braces are disposed outside the outermost layer interlayer insulation of the layer winding and are spaced apart on the outer side surface of the heat-resistant paper.

[0008] In some embodiments, the winding is a disk winding, and the disk winding is composed of a plurality of wire disks stacked on each other, and the wire disks are formed by winding electromagnetic wires. The first insulation structure includes turn insulation, and the turn insulation is disposed outside the electromagnetic wires of the wire disk. The second insulation structure includes a first insulating cylinder, a plurality of inner braces, a plurality of outer braces, a plurality of radial oil duct pads, insulating end rings, and shielding screens. The first insulating cylinder is disposed around the inside of the disk winding. The plurality of inner braces are spaced apart between the first insulating cylinder and the inside of the disk winding. The plurality of outer braces are spaced around the outer side surface of the disk winding. The plurality of radial oil duct pads are spaced between adjacent wire disks to form a radial oil duct between adjacent wire disks. The insulating end rings are disposed at the upper and lower ends of the disk winding. The shielding screens are arranged outside the plurality of outer braces.

[0009] In some embodiments, the second insulation structure further includes a plurality of oil baffle plates; the oil baffle plates are disposed between the outer side surface of the disk winding and the shielding screens and are used for guiding the insulating oil in the oil-immersed transformer.

[0010] Thus, for the insulation structure provided by the embodiments of the present invention, by providing the first insulation structure at the first position of the winding and using an insulation material of class B or above for the material of the first insulation structure, the heat resistance of the first insulation structure can be improved and the life of the first insulation structure can be extended, thereby extending the life of the winding while the first insulation structure provides normal insulation at the first position; by providing the second insulation structure at the second position of the winding and using an A-class insulation material for the material of the second insulation structure, the material cost of the second insulation structure can be reduced on the basis that the second insulation structure provides normal insulation at the second position; compared with the prior art in which only the same grade of insulation material is used, the insulation structure in the present invention uses different grades of insulation materials at different positions of the winding, which helps to reduce the cost of the insulation material on the winding while meeting the insulation requirements of different positions, thereby improving the economy of the oil-immersed transformer.

[0011] In a second aspect, an embodiment of the present utility model further provides an oil-immersed transformer, which includes a fuel tank, a core body, insulating oil, and a winding external insulation structure. The core body is disposed inside the fuel tank and includes an iron core and at least two windings that successively surround the outer periphery of the iron core column of the iron core from the inside out. Among them, two adjacent windings are respectively a first winding and a second winding. The insulating oil is filled in the fuel tank and is used to provide a liquid immersion environment and liquid insulation for the core body. The winding external insulation structure includes an iron core column insulation; the iron core column insulation is disposed between the iron core column of the iron core and the first winding; the iron core column insulation is composed of a second insulating cylinder, an adjusting cardboard, and a fixed support bar that are successively arranged from the inside out. Among them, the material of the second insulating cylinder is an insulating material of class B or above, and the materials of the adjusting cardboard and the fixed support bar are class A insulating materials, so that the overall iron core column insulation meets the insulation requirements at high temperatures. The insulating structure described in the first aspect is disposed on the first winding; the insulating structure described in the first aspect is disposed on the second winding.

[0012] In a third aspect, an embodiment of the present utility model further provides an oil-immersed transformer, which includes a fuel tank, a core body, insulating oil, and a winding external insulation structure. The core body is disposed inside the fuel tank and includes an iron core and windings that successively surround the outer periphery of the iron core column of the iron core from the inside out. The insulating oil is filled in the fuel tank and is used to provide a liquid immersion environment and liquid insulation for the core body. The winding external insulation structure includes an iron core column insulation; the iron core column insulation is disposed between the iron core column of the iron core and the first winding; the iron core column insulation is composed of a second insulating cylinder, an adjusting cardboard, and a fixed support bar that are successively arranged from the inside out. Among them, the material of the second insulating cylinder is an insulating material of class B or above, and the materials of the adjusting cardboard and the fixed support bar are class A insulating materials, so that the overall iron core column insulation meets the insulation requirements at high temperatures. A hybrid insulation structure is disposed on the winding; the material of the hybrid insulation structure is obtained by combining an insulating material of class B or above and a class A insulating material.

[0013] In some embodiments, the insulating oil is natural ester oil or synthetic ester oil.

[0014] In some embodiments, the oil-immersed transformer further includes at least one oil conservator and at least one nitrogen gas tank. The oil conservator is disposed above the fuel tank and is communicated with the fuel tank. The nitrogen gas tank is disposed outside the middle of the fuel tank and is communicated with the oil conservator. Compressed nitrogen is filled inside the nitrogen gas tank. In the vertical direction, the orthographic projection of the oil conservator and the orthographic projection of the nitrogen gas tank are both within the orthographic projection range of the fuel tank.

[0015] In some embodiments, an automatic pressure relief valve and a pressure sensor are disposed on the nitrogen gas tank.

[0016] The oil-immersed transformer provided by the embodiment of the present utility model has the same beneficial effects as the above-mentioned insulation structure, which will not be elaborated herein. Description of the Drawings

[0017] Figure 1 : A structural diagram of an oil-immersed transformer provided by an embodiment of the present utility model;

[0018] Figure 2 : A partial structural diagram of the body of an oil-immersed transformer provided by an embodiment of the present utility model. Detailed Embodiment

[0019] To enable those skilled in the art to better understand the technical solution of the present utility model, the present utility model will be further described in detail below with reference to the drawings and embodiments.

[0020] Embodiment 1:

[0021] As Figure 1 and Figure 2 shown, an embodiment of the present utility model provides an insulation structure, which is applied to the winding of an oil-immersed transformer to achieve the insulation of the winding.

[0022] This insulation structure is arranged on the winding of the oil-immersed transformer. This insulation structure includes a first insulation structure and a second insulation structure. The first insulation structure is arranged at the first position of the winding, and the material of the first insulation structure is a B-class or above B-class insulation material. The second insulation structure is arranged at the second position of the winding, and the material of the second insulation structure is an A-class insulation material.

[0023] Exemplarily, the above-mentioned winding can be a layer winding or a disk winding.

[0024] The B-class insulation material refers to an insulation material whose allowable maximum working temperature is 130 °C. The A-class insulation material refers to an insulation material whose allowable maximum working temperature is 105 °C.

[0025] Exemplarily, the above-mentioned first position is the position on the winding where the temperature rise is relatively large (for example, the temperature rises to 120 °C), and the second position is the position on the winding where the temperature rise is relatively small (for example, the temperature rises to 100 °C).

[0026] The B-class or above B-class insulation material can work at a higher temperature. Therefore, when the first insulation structure provides normal insulation at the first position, the heat resistance of the first insulation structure can be improved, the service life of the first insulation structure can be extended, thereby extending the service life of the winding, and the overload resistance of the winding can be improved. The material of the second insulation structure is an A-class insulation material. Therefore, while providing insulation at the second position, the material cost of the second insulation structure can be reduced.

[0027] Accordingly, the insulation structure provided by the embodiments of the present utility model sets the first insulation structure at the first position of the winding, and the material of the first insulation structure is made of Class B or higher insulation material, which can improve the heat resistance of the first insulation structure and extend the life of the first insulation structure and thus the life of the winding while providing normal insulation at the first position; by setting the second insulation structure at the second position of the winding and making the material of the second insulation structure be Class A insulation material, the material cost of the second insulation structure can be reduced on the basis of providing normal insulation at the second position; compared with the prior art that only uses the same grade of insulation material, the insulation structure in the present utility model uses different grades of insulation material at different positions of the winding, which helps to reduce the cost of the insulation material on the winding on the basis of meeting the insulation requirements at different positions, thereby improving the economy of the oil-immersed transformer.

[0028] In some embodiments, the first insulation structure is used to achieve insulation at the first position of the winding, and the second insulation structure is used to achieve insulation at the second position of the winding. Among them, during the operation of the winding, the temperature at the second position is less than or equal to 105 °C, and the temperature at the first position is greater than 105 °C and less than or equal to 130 °C.

[0029] The temperature at the second position is less than or equal to 105 °C. Therefore, the second insulation structure made of Class A insulation material has sufficient heat resistance at the second position and provides normal insulation for the second position. The temperature at the first position is greater than 105 °C and less than or equal to 130 °C. Therefore, the first insulation structure made of Class B or higher insulation material can have better heat resistance at the first position, thereby improving the overload resistance of the winding, extending the life of the first insulation structure, and enabling the first insulation structure to maintain good insulation performance for a long time at the first position.

[0030] In some embodiments, as Figure 2 shown, the above-mentioned winding is a layer winding (such as Figure 2 the first winding 8 in), and the layer winding is formed by multiple layers of foil conductors 10 wound from the inside to the outside. The first insulation structure includes interlayer insulation 13, end insulation 15, a plurality of first axial braces 14 and heat-resistant paper. The interlayer insulation 13 is arranged between adjacent two layers of foil conductors 10 of the layer winding. The end insulation 15 is arranged at the upper and lower ends of the layer winding. The plurality of first axial braces 14 are fixed between adjacent two layers of foil conductors 10 of the layer winding through oil duct sticker paper; an axial oil duct is formed between two adjacent first axial braces 14. The heat-resistant paper is coated on the outer side of the layer winding.

[0031] The materials of the interlayer insulation 13, the end insulation 15 and the oil duct sticker can all be DPE. The interlayer insulation 13 is used to provide insulation between the layers of the multi-layer foil conductor 10. The end insulation 15 is used to provide insulation at the upper and lower ends of the layer winding.

[0032] Exemplarily, a plurality of first axial braces 14 are evenly spaced between adjacent two layers of the foil conductors 10 of the layer winding.

[0033] The material of the first axial brace 14 can be an epoxy fiberglass rod of class B or above, which is used to provide support and insulation between adjacent two layers of the foil conductors 10 of the layer winding.

[0034] The number of layers of the heat-resistant paper can be four or more layers, and the material of the heat-resistant paper can be aromatic polyamide fiber paper or Nomex paper, etc., which is used to provide insulation on the outer side of the layer winding.

[0035] Through the above settings, the interlayer insulation 13, the end insulation 15, the first axial brace 14, the oil duct sticker and the heat-resistant paper can have good insulation and heat resistance capabilities, improve the service life of the interlayer insulation 13, the end insulation 15, the first axial brace 14, the oil duct sticker and the heat-resistant paper, and are beneficial to maintaining the insulation performance of the interlayer insulation 13, the end insulation 15, the first axial brace 14, the oil duct sticker and the heat-resistant paper for a long time.

[0036] As Figure 2 shown, the second insulation structure includes a plurality of second axial braces 16. The plurality of second axial braces 16 are arranged outside the outermost layer interlayer insulation 13 of the layer winding and are spaced on the outer side of the heat-resistant paper.

[0037] Exemplarily, the plurality of second axial braces 16 are evenly arranged on the outer side of the heat-resistant paper. The thickness of the second axial brace 16 is greater than or equal to the thickness of the first axial brace 14.

[0038] The material of the second axial brace 16 can be cellulose.

[0039] Through the above settings, the second axial brace 16 can provide insulation outside the layer winding and reduce the material cost of the second axial brace 16.

[0040] In some other embodiments, as Figure 1 and Figure 2 shown, the above winding is a pancake winding (such as the second winding 9 in Figure 2 ), and the pancake winding is composed of a plurality of wire cakes stacked on each other, and the wire cake is formed by winding the magnet wire 11. The first insulation structure includes inter-turn insulation, and the inter-turn insulation is arranged outside the magnet wire 11 of the wire cake.

[0041] The turn-to-turn insulation can be the turn-to-turn wrapping paper made of DPE material. The turn-to-turn wrapping paper is wrapped around the outside of the magnet wire 11 and is used to provide insulation on the outside of the magnet wire 11 of the coil section.

[0042] Through the above arrangement, the turn-to-turn insulation can have better heat resistance, improve the service life of the turn-to-turn insulation, and is beneficial to maintaining the insulation performance of the turn-to-turn insulation for a long time.

[0043] As Figure 2 shown, the second insulation structure includes a first insulation cylinder 19, a plurality of inner support bars 20, a plurality of outer support bars 21, a plurality of radial oil duct pads 22, an insulation end ring 24, and a shielding screen 25. The first insulation cylinder 19 is arranged around the inside of the disk-type winding. The plurality of inner support bars 20 are arranged at intervals between the first insulation cylinder 19 and the inside of the disk-type winding. The plurality of outer support bars 21 are arranged around the outer side surface of the disk-type winding at intervals. The plurality of radial oil duct pads 22 are arranged at intervals between adjacent two coil sections to form a radial oil duct between the adjacent two coil sections. The insulation end ring 24 is arranged at the upper end part and the lower end part of the disk-type winding. The shielding screen 25 is arranged around the outside of the plurality of outer support bars 21.

[0044] The materials of the first insulation cylinder 19, the plurality of inner support bars 20, the plurality of outer support bars 21, the plurality of radial oil duct pads 22, the insulation end ring 24, and the shielding screen 25 can all be cellulose.

[0045] As Figure 2 shown, the first insulation cylinder 19 is used to provide insulation on the inside of the disk-type winding (such as Figure 2 the second winding 9 in ). The inner support bars 20 are used to provide support and insulation between the first insulation cylinder 19 and the inside of the disk-type winding. The outer support bars 21 are used to provide support and insulation on the outer side surface of the disk-type winding. The radial oil duct pads 22 are used to provide support and insulation between adjacent two coil sections, facilitating the flow of the insulating oil in the transformer through the radial oil duct to take away the heat on the coil sections. The insulation end ring 24 is used to provide insulation at the upper end part and the lower end part of the disk-type winding. The shielding screen 25 is used to provide insulation outside the outer support bars 21 and provide protection for the outer support bars 21.

[0046] Through the above arrangement, on the basis of enabling the first insulation cylinder 19, the plurality of inner support bars 20, the plurality of outer support bars 21, the plurality of radial oil duct pads 22, the insulation end ring 24, and the shielding screen 25 to provide insulation, the material costs of the first insulation cylinder 19, the plurality of inner support bars 20, the plurality of outer support bars 21, the plurality of radial oil duct pads 22, the insulation end ring 24, and the shielding screen 25 can be reduced.

[0047] In some embodiments, as Figure 2 shown, the second insulation structure further includes a plurality of oil baffles 23; the oil baffles 23 are arranged between the outer side surface of the disk-type winding and the shielding screen 25 and are used to guide the insulating oil 6 in the oil-immersed transformer.

[0048] Exemplarily, the oil baffle 23 is disposed between the radial oil duct spacer 22 and the coil turn in contact with the radial oil duct spacer 22.

[0049] The material of the oil baffle 23 may be cellulose.

[0050] The oil baffle 23 has a guiding effect on the insulating oil in the transformer, which can accelerate the oil flow speed and efficiency, thereby reducing the hot spot and average temperature rise of the winding.

[0051] The utility model inventor found according to the simulated temperature field distribution and test data during the operation of the winding that the temperature rise value of the winding gradually increases uniformly from the lower part to the upper part in the axial direction, such as gradually increasing from 15K to 60K; while the temperature rise change is not significant in the radial direction, and the inside is higher than the outside. Therefore, class B or above insulating materials are used in the high-temperature area (for example, the area with a temperature rise of 60K), and the high-temperature area can be the area in direct contact with the conductor or in contact through turn insulation but with poor heat dissipation, the hot spot area, etc.; cellulose is used in the low-temperature area (for example, the area with a temperature rise of 15K), and the low-temperature area can be the oil duct with good heat dissipation or the main control duct area far from the conductor, etc. The core column insulation between the core and the low-voltage winding in the radial direction and the yoke insulation between the core and the low-voltage winding in the axial direction, the main insulation at these two places are respectively selected as hybrid insulation and cellulose insulation, and the longitudinal insulation at these three places of the low-voltage winding, high-voltage winding, and the main control duct insulation between the high and low voltages are respectively selected as hybrid insulation, hybrid insulation, and fiber insulation.

[0052] Embodiment 2:

[0053] As Figure 1 and Figure 2 shown, the embodiment of the present utility model further provides an oil-immersed transformer, which includes an oil tank 1, a core body 27, insulating oil 6, and a winding outer insulation structure. The core body 27 is disposed inside the oil tank 1 and includes a core 7 and at least two windings successively surrounding the outer circumference of the core column of the core 7 from the inside to the outside, wherein two adjacent windings are respectively a first winding 8 and a second winding 9. The insulating oil 6 is filled in the oil tank 1 for providing a liquid immersion environment and liquid insulation for the core body 27. The winding outer insulation structure includes a core column insulation 12. The core column insulation 12 is disposed between the core column of the core 7 and the first winding 8; the core column insulation 12 is composed of a second insulating cylinder, an adjusting cardboard, and a fixed stay successively arranged from the inside to the outside, wherein the material of the second insulating cylinder is a class B or above insulating material, and the materials of the adjusting cardboard and the fixed stay are class A insulating materials, so that the overall core column insulation meets the insulation requirements at high temperatures. The insulation structure in Embodiment 1 is provided on the first winding 8; the insulation structure in Embodiment 1 is provided on the second winding 9.

[0054] The above-mentioned oil-immersed transformer can be applied to the green clean energy field with special load conditions such as offshore wind power and photovoltaic.

[0055] The fuel tank 1 is used to provide a housing space and protection for the body 27 and the insulating oil 6 inside it.

[0056] Exemplarily, the number of windings around the outer periphery of the core column of the core 7 can be two, three, etc. The windings can be low-voltage windings, high-voltage windings, regulating windings, etc., and the types of windings can be layer windings or disc windings.

[0057] Exemplarily, Figure 1 and Figure 2 in, the first winding 8 is a low-voltage winding and the second winding 9 is a high-voltage winding.

[0058] It has been verified that after the insulation structure is immersed in the insulating oil 6, the heat resistance performance of the insulation structure can be improved, the service life of various insulating materials in the insulation structure can be extended, and thus the insulation life of the oil-immersed transformer can be extended.

[0059] The core column insulation 12 is used to provide insulation between the core column of the core 7 and the first winding 8.

[0060] Exemplarily, the material of the second insulating cylinder is epoxy glass fiber, and the materials of the regulating cardboard and the fixed support bar are cellulose.

[0061] Through the above settings, the epoxy glass fiber ensures the heat resistance ability of the second insulating cylinder, so the radial stress of the first winding 8 against sudden short circuits can be improved; the above settings also reduce the material costs of the regulating cardboard and the fixed support bar.

[0062] The insulating oil 6 is filled in the windings, the insulation structure on the first winding 8, and the insulation structure on the second winding 9, so as to jointly form the insulation system of the oil-immersed transformer with the insulation structure on the first winding 8 and the insulation structure on the second winding 9. Therefore, the heat resistance performance of the windings can be improved, the load capacity of the oil-immersed transformer can be enhanced, the insulation life of the oil-immersed transformer can be increased, and the material costs of the insulation system can be reduced, thereby reducing the production costs of the oil-immersed transformer and improving the economy of the oil-immersed transformer.

[0063] Embodiment 3:

[0064] As Figure 1 and Figure 2As shown in the figure, the embodiment of the present utility model further provides an oil-immersed transformer, which includes an oil tank 1, a core body 27, insulating oil 6, and a winding outer insulation structure. The core body 27 is arranged inside the oil tank 1 and includes an iron core 7 and windings that successively surround the outer circumference of the core column of the iron core 7 from the inside to the outside. The insulating oil 6 is filled in the oil tank 1 to provide a liquid immersion environment and liquid insulation for the core body 27. The winding outer insulation structure includes a core column insulation 12. The core column insulation 12 is arranged between the core column of the iron core 7 and the first winding 8; the core column insulation 12 is composed of a second insulating cylinder, an adjusting cardboard, and a fixed support strip arranged in sequence from the inside to the outside. Among them, the material of the second insulating cylinder is an insulating material of class B or above, and the materials of the adjusting cardboard and the fixed support strip are class A insulating materials, so that the overall core column insulation meets the insulation requirements at high temperatures. The winding includes a hybrid insulation structure; the material of the hybrid insulation structure is obtained by combining an insulating material of class B or above and a class A insulating material.

[0065] The hybrid insulation structure can reduce the cost of the hybrid insulation structure while meeting the insulation requirements.

[0066] The insulating oil 6 is filled in the winding and the hybrid insulation structure, so as to jointly form an insulation system of the oil-immersed transformer with the hybrid insulation structure. Therefore, the heat resistance of the winding can be improved, the load capacity of the oil-immersed transformer can be enhanced, the insulation life of the oil-immersed transformer can be increased, and the material cost of the insulation system can be reduced, thereby reducing the production cost of the oil-immersed transformer and improving the economy of the oil-immersed transformer.

[0067] In some embodiments, as Figure 2 shown, the winding outer insulation structure further includes a main channel insulation 18 and a yoke insulation 26. The main channel insulation 18 is arranged between the first winding 8 and the second winding 9, and the material of the main channel insulation 18 is a class A insulating material. The yoke insulation 26 is arranged between the yoke of the iron core 7 and the first winding 8 and the second winding 9, and the material of the yoke insulation 26 is a class A insulating material.

[0068] In some examples, as Figure 2 shown, in the direction from the first winding 8 to the second winding 9, the main channel insulation 18 includes an insulating cardboard, a support strip, and a corner ring 17 arranged in sequence.

[0069] Exemplarily, the materials of the insulating cardboard, the support strip, and the corner ring 17 are all cellulose.

[0070] The insulating cardboard, the support strip, and the corner ring 17 do not directly contact the conductor and the heating part, and their temperature is similar to that of the insulating oil 6. Therefore, using cellulose materials can meet the heat resistance requirements at the insulating cardboard, the support strip, and the corner ring 17, which is beneficial to reducing the material cost of the insulating cardboard, the support strip, and the corner ring 17.

[0071] The yoke insulation 26 is used to provide insulation between the yoke of the iron core 7 and the first winding 8 and the second winding 9. The material of the yoke insulation 26 is cellulose.

[0072] The yoke insulation 26 does not directly contact the conductor and the heating part, and its temperature is similar to that of the insulating oil 6. Therefore, using cellulose material can meet the heat resistance requirements between the yoke of the iron core 7 and the first winding 8 and the second winding 9, which is beneficial to reducing the material cost of the yoke insulation 26.

[0073] It should be noted that when assembling the oil-immersed transformer, the first winding 8 is first sleeved into the second winding 9, and then sleeved into the iron core 7 after the main control path insulation 18 and the core column insulation 12 are assembled.

[0074] In some embodiments, the insulating oil 6 is natural ester oil or synthetic ester oil.

[0075] Exemplarily, the insulating oil 6 is K-class ignition point ester oil, and an economical natural ester with an ignition point exceeding 360°C is selected, such as FR3 natural ester insulating oil or vegetable oil.

[0076] Natural ester oil and synthetic ester oil are non-toxic, harmless and degradable environmental protection materials, which are beneficial to improving the environmental protection level of the oil-immersed transformer. Natural ester oil and synthetic ester oil have a high ignition point and self-extinguishing properties, which improve the fire prevention and flame retardant capabilities of the oil-immersed transformer. The maximum heat resistance temperature of the insulation system of the oil-immersed transformer formed by natural ester oil or synthetic ester oil and the insulation structure in Embodiment 1 is 20°C higher than that of the insulation system formed by ordinary mineral oil and heat-resistant paper, which improves the temperature rise limit value, overload capacity and service life of the oil-immersed transformer.

[0077] In some embodiments, the first winding 8 is a layer winding; or, the second winding 9 is a layer winding; or, both the first winding 8 and the second winding 9 are layer windings. The insulating oil 6 is natural ester oil, and the thickness of the axial oil duct is greater than or equal to 4 mm.

[0078] Exemplarily, the first winding 8 is a low-voltage winding. When the height of the first winding 8 is within 500 mm, the thickness of the axial oil duct can be 4 mm; when the height of the first winding 8 is between 500 mm and 1000 mm (excluding 500 mm and 1000 mm), the thickness of the axial oil duct can be 5 mm; when the height of the first winding 8 is above 1000 mm, the thickness of the axial oil duct can be 6 mm.

[0079] In some other examples, the first winding 8 is a disk winding; or, the second winding 9 is a disk winding; or, both the first winding 8 and the second winding 9 are disk windings. The insulating oil 6 is natural ester oil, and the thickness of the radial oil duct is greater than or equal to 3 mm.

[0080] Exemplarily, in this case, the thickness of the radial oil duct can be 3 mm, 4 mm, 5 mm, etc. It can be understood that the thickness of the radial oil duct spacer 22 is the same as that of the radial oil duct.

[0081] Through the above settings, the flow rate of the natural ester oil can be increased, and the heat dissipation efficiency of the natural ester oil can be improved.

[0082] In some embodiments, as Figure 1 shown, the oil-immersed transformer further includes at least one oil conservator 2 and at least one nitrogen tank 3. The oil conservator 2 is arranged above the oil tank 1 and is communicated with the oil conservator 2. The nitrogen tank 3 is arranged outside the middle of the oil tank 1 and is communicated with the oil conservator 2. The nitrogen tank 3 is filled with compressed nitrogen inside. In the vertical direction, the orthographic projection of the oil conservator 2 and the orthographic projection of the nitrogen tank 3 are both within the orthographic projection range of the oil tank 1.

[0083] Exemplarily, the number of the oil conservator 2 and the nitrogen tank 3 can be set as required. Figure 1 Two oil conservators 2 and two nitrogen tanks 3 are shown in

[0084] In other examples, the nitrogen tank 3 can be separately arranged from the oil tank 1, for example, directly placed on the same support as the oil tank 1.

[0085] Exemplarily, as Figure 1 shown, the shapes and sizes of the two oil conservators 2 are the same. For example, the shapes of the two oil conservators 2 are both rectangular, and the two oil conservators 2 are arranged on the opposite sides above the oil tank 1 to make full use of the space above the oil tank 1, reduce the space occupied by the oil conservator 2, and contribute to the miniaturization of the oil-immersed transformer.

[0086] Exemplarily, the oil conservator 2 and the nitrogen tank 3 are communicated through a first hose 4.

[0087] The above-mentioned first hose 4 can be a PTFE hose. The outside of the PTFE hose is an SS304 stainless steel braided layer, and the interface is a pipe thread connection, which can facilitate the routing design of the first hose 4 and improve the temperature resistance, airtightness and pressure resistance of the first hose 4.

[0088] The two oil conservators 2 can be communicated through a second hose 5, and the second hose 5 can also be a PTFE hose.

[0089] Two oil conservators 2 and two nitrogen gas boxes 3 are connected through a first hose 4 and a second hose 5 and then connected to the inside of the fuel tank 1 to form a sealed chamber, and the sealed chamber is filled with nitrogen gas. When the volume of the insulating oil 6 in the fuel tank 1 changes due to temperature changes, the sealed chamber can maintain the stability of the air pressure in the sealed chamber without setting a traditional moisture absorber and capsule structure, which is beneficial to reducing the volume occupied by the capsule and also avoiding the high-frequency maintenance requirements of the moisture absorber and capsule of the traditional transformer, thereby achieving maintenance-free operation. The sealed chamber can also isolate the insulating oil 6 in the fuel tank 1 from the external air, so that the insulating oil 6 and the insulating structure are protected from being contaminated by oxygen, water, impurities, etc. in the external air, which is beneficial to reducing the aging and oxidation rates of the insulating oil 6 and the insulating structure, thereby improving the service life of the insulating oil 6 and the insulating structure and enhancing the service life of the oil-immersed transformer.

[0090] It should be noted that before filling nitrogen gas into the nitrogen gas box 3, the nitrogen gas box 3 needs to be evacuated, and the sealing performance of the nitrogen gas box 3 also needs to be detected.

[0091] Exemplarily, the shape of the nitrogen gas box 3 is rectangular or other shapes, and the two nitrogen gas boxes 3 are arranged on opposite sides of the fuel tank 1, so that in the vertical direction, the orthographic projection of the oil conservator 2 and the orthographic projection of the nitrogen gas box 3 are both within the orthographic projection range of the fuel tank 1.

[0092] This can reduce the space occupied by the oil conservator 2 and the nitrogen gas box 3, which is beneficial to the miniaturization of the oil-immersed transformer.

[0093] In some examples, an automatic pressure relief valve 28 and a pressure sensor 29 are provided on the nitrogen gas box 3.

[0094] When the nitrogen gas box 3 is operating normally, the change range of the air pressure inside it is 0 - 45 kPa.

[0095] Exemplarily, the pressure relief action value of the automatic pressure relief valve 28 can be set to 40 kPa - 45 kPa, for example, set to 45 kPa. At this time, the action value of the pressure relief valve on the oil-immersed transformer can be set to 100 kPa to avoid the misoperation of the pressure relief valve on the oil-immersed transformer due to excessive pressure inside the nitrogen gas box 3 and to protect the safety of the nitrogen gas box 3.

[0096] The pressure sensor 29 is used to transmit the pressure value inside the nitrogen gas box 3 to the outside and display it through an external display, so that the staff can quickly obtain the pressure value inside the nitrogen gas box 3 outside.

[0097] Through the above settings, it is possible to avoid damage caused by excessive pressure inside the nitrogen gas box 3 and improve the safety of the oil-immersed transformer.

[0098] It is understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present utility model. However, the present utility model is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present utility model, and these modifications and improvements are also regarded as the protection scope of the present utility model.

Claims

1. An insulating structure is provided on the winding of an oil-immersed transformer, characterized in that, The insulation structure includes: A first insulation structure disposed at a first position of the winding, and the material of the first insulation structure is an insulation material of class B or above; and, A second insulation structure disposed at a second position of the winding, and the material of the second insulation structure is an insulation material of class A.

2. The insulating structure according to claim 1, wherein, The first insulation structure is used to achieve insulation at the first position of the winding, and the second insulation structure is used to achieve insulation at the second position of the winding; Wherein, during the operation of the winding, the temperature at the second position is less than or equal to 105 °C, and the temperature at the first position is greater than 105 °C and less than or equal to 130 °C.

3. The insulating structure according to claim 1, wherein The winding is a layer winding formed by multiple layers of foil conductors (10) wound around from the inside to the outside; The first insulation structure includes: Interlayer insulation (13) disposed between adjacent two layers of foil conductors (10) of the layer winding; End insulation (15) disposed at the upper and lower ends of the layer winding; A plurality of first axial braces (14) fixed between adjacent two layers of foil conductors (10) of the layer winding by oil duct sticker paper; an axial oil duct is formed between two adjacent first axial braces (14); and, Heat-resistant paper covering the outer side surface of the layer winding; The second insulation structure includes a plurality of second axial braces (16); the plurality of second axial braces (16) are disposed outside the outermost layer interlayer insulation (13) of the layer winding and are spaced apart on the outer side surface of the heat-resistant paper.

4. The insulating structure according to claim 1, wherein The winding is a pancake winding composed of a plurality of stacked wire cakes, and the wire cakes are formed by winding electromagnetic wires (11); The first insulation structure includes turn-to-turn insulation disposed outside the electromagnetic wires (11) of the wire cake; The second insulation structure includes: A first insulating cylinder (19) disposed around the inside of the pancake winding; A plurality of inner braces (20) spaced apart between the first insulating cylinder (19) and the inside of the pancake winding; A plurality of outer braces (21) spaced apart around the outer side surface of the pancake winding; A plurality of radial oil duct spacers (22) spaced apart between adjacent two wire cakes to form a radial oil duct between adjacent two wire cakes; Insulating end rings (24) disposed at the upper and lower ends of the pancake winding; and, A screen (25) surrounding the outside of the plurality of outer braces (21).

5. The insulating structure according to claim 4, characterized in that, The second insulation structure further includes a plurality of oil baffles (23); The oil baffles (23) are disposed between the outer side surface of the pancake winding and the screen (25) and are used to guide the insulating oil (6) in the oil-immersed transformer.

6. An oil-immersed transformer, characterized in that, Including: An oil tank (1); A core body (27) disposed in the oil tank (1), including a core (7) and at least two windings successively wound around the outer periphery of the core column of the core (7) from the inside to the outside, wherein two adjacent windings are a first winding (8) and a second winding (9) respectively; Insulating oil (6) filled in the oil tank (1) for providing a liquid immersion environment and liquid insulation for the core body (27); and, The external insulation structure of the winding includes the core column insulation (12); the core column insulation (12) is arranged between the core column of the core (7) and the first winding (8); the core column insulation (12) is composed of a second insulation cylinder, an adjusting cardboard, and a fixed brace arranged in sequence from the inside to the outside, wherein the material of the second insulation cylinder is an insulation material of class B or above, and the materials of the adjusting cardboard and the fixed brace are class A insulation materials, so that the overall core column insulation meets the insulation requirements at high temperatures; The insulation structure according to any one of claims 1-5 is provided on the first winding (8); the insulation structure according to any one of claims 1-5 is provided on the second winding (9).

7. An oil-immersed transformer, characterized in that, Including: An oil tank (1); A body (27) arranged in the oil tank (1), including a core (7) and at least two windings successively surrounding the outer periphery of the core column of the core (7) from the inside to the outside, wherein two adjacent windings are respectively a first winding (8) and a second winding (9); Insulating oil (6) filled in the oil tank (1) for providing a liquid immersion environment and liquid insulation for the body (27); and, The external insulation structure of the winding includes the core column insulation (12); the core column insulation (12) is arranged between the core column of the core (7) and the first winding (8); the core column insulation (12) is composed of a second insulation cylinder, an adjusting cardboard, and a fixed brace arranged in sequence from the inside to the outside, wherein the material of the second insulation cylinder is an insulation material of class B or above, and the materials of the adjusting cardboard and the fixed brace are class A insulation materials, so that the overall core column insulation meets the insulation requirements at high temperatures; The winding includes a hybrid insulation structure; the material of the hybrid insulation structure is obtained by combining an insulation material of class B or above and a class A insulation material.

8. The oil-immersed transformer according to claim 6 or 7, characterized in that, The insulating oil (6) is natural ester oil or synthetic ester oil.

9. The oil-immersed transformer according to claim 6 or 7, characterized in that, Further including: At least one oil conservator (2) arranged above the oil tank (1) and communicated with the oil tank (1); And, At least one nitrogen tank (3) arranged outside the middle of the oil tank (1) and communicated with the oil conservator (2), and the nitrogen tank (3) is filled with compressed nitrogen; In the vertical direction, the orthographic projection of the oil conservator (2) and the orthographic projection of the nitrogen tank (3) are both within the orthographic projection range of the oil tank (1).

10. The oil-immersed transformer according to claim 9, wherein, An automatic pressure relief valve (28) and a pressure sensor (29) are arranged on the nitrogen tank (3).

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