Insulation structure and oil-immersed transformer

Abstract

The invention discloses an insulating structure and an oil-immersed transformer, which can reduce the cost of insulating materials on a winding and improve the economical efficiency of the transformer by using insulating 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 invention belongs to the technical field of transformer manufacturing, and in particular relates to an insulation structure and an oil-immersed transformer. Background Art

[0002] The windings in the transformer are usually provided with insulating materials to ensure the insulation of the windings. The insulation grade of the insulating materials is usually the same as the insulation grade of the transformer.

[0003] However, during the operation of the transformer, the temperature rise at different positions in the winding is different. In order to facilitate material selection and maintain reliable insulation of the winding, all insulating materials are usually set to materials with the same higher insulation grade in the prior art. This increases the cost of the insulating material on the winding and affects the economy of the transformer. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an insulation structure and an oil-immersed transformer in view of the above-mentioned deficiencies in the prior art. By using insulation materials of different insulation grades at different positions of the winding, the cost of the insulation material on the winding can be reduced and the economy of the transformer can be improved.

[0005] In a first aspect, an embodiment of the present invention provides an insulation structure, which is arranged on a winding of an oil-immersed transformer, and includes a first insulation structure and a second insulation structure. The first insulation structure is arranged at a first position of the winding, and the material of the first insulation structure is an insulation material of Class B or above. The second insulation structure is arranged at a second position of the winding, and the material of the second insulation structure is an insulation material of Class A.

[0006] In some embodiments, the first insulating structure is used to achieve insulation at a first position of the winding, and the second insulating structure is used to achieve insulation at a second position of the winding. During the operation of the winding, the temperature of the second position is less than or equal to 105°C, and the temperature of 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 wires wrapped from the inside to the outside. The first insulation structure includes interlayer insulation, end insulation, multiple first axial struts and heat-resistant paper. The interlayer insulation is arranged between two adjacent layers of foil wires of the layer winding. The end insulation is arranged at the upper end and the lower end of the layer winding. Multiple first axial struts are fixed between two adjacent layers of foil wires of the layer winding by oil channel adhesive paper; an axial oil channel is formed between two adjacent first axial struts. Heat-resistant paper is coated on the outer side of the layer winding. The second insulation structure includes multiple second axial struts; multiple second axial struts are arranged outside the outermost interlayer insulation of the layer winding, and are arranged at intervals on the outer side of the heat-resistant paper.

[0008] In some embodiments, the winding is a pancake winding, which is composed of a plurality of coils stacked on each other, and the coils are formed by winding electromagnetic wires. The first insulating structure includes turn-to-turn insulation, and the turn-to-turn insulation is arranged on the outside of the electromagnetic wire of the coil. The second insulating structure includes a first insulating cylinder, a plurality of inner support bars, a plurality of outer support bars, a plurality of radial oil passage pads, an insulating end ring and a screen. The first insulating cylinder is arranged around the inner side of the pancake winding. A plurality of inner support bars are arranged between the first insulating cylinder and the inner side of the pancake winding at intervals. A plurality of outer support bars are arranged around the outer side of the pancake winding at intervals. A plurality of radial oil passage pads are arranged between two adjacent coils at intervals to form radial oil passages between two adjacent coils. The insulating end rings are arranged at the upper end and the lower end of the pancake winding. The screen is arranged around the outer side of the plurality of outer support bars.

[0009] In some embodiments, the second insulating structure further includes a plurality of oil baffles; the oil baffles are disposed between the outer side surface of the pancake winding and the enclosure to guide the insulating oil in the oil-immersed transformer.

[0010] Therefore, the insulation structure provided by the embodiment of the present invention can improve the heat resistance of the first insulation structure while providing normal insulation at the first position by arranging the first insulation structure at the first position of the winding, and extend the life of the first insulation structure and thus extend the life of the winding by making the material of the first insulation structure adopt Class B or above insulation material; by arranging the second insulation structure at the second position of the winding and making the material of the second insulation structure adopt 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 insulation materials of the same grade, the insulation structure in the present invention uses insulation materials of different grades at different positions of the winding, which helps to reduce the cost of insulation materials on the winding while meeting the insulation requirements at different positions, thereby improving the economy of the oil-immersed transformer.

[0011] In a second aspect, an embodiment of the present invention further provides an oil-immersed transformer, the oil-immersed transformer comprising an oil tank, a body, insulating oil and an outer insulation structure of the winding. The body is arranged in the oil tank, comprising an iron core and at least two windings sequentially surrounding the outer periphery of the iron core column of the iron core from the inside to the outside, wherein two adjacent windings are respectively a first winding and a second winding. Insulating oil is filled in the oil tank to provide a liquid immersion environment and liquid insulation for the body. The outer insulation structure of the winding comprises an iron core column insulation; the iron core column insulation is arranged between the iron core column of the iron core and the first winding; the iron core column insulation comprises a second insulating cylinder, an adjusting paperboard, and a fixed support bar arranged sequentially from the inside to the outside, wherein the material of the second insulating cylinder is an insulating material of Class B or above, and the material of the adjusting paperboard and the fixed support bar is an insulating material of Class A, so that the insulation of the entire iron core column meets the insulation requirements under high temperature. The insulating structure described in the first aspect is arranged on the first winding; the insulating structure described in the first aspect is arranged on the second winding.

[0012] In a third aspect, an embodiment of the present invention further provides an oil-immersed transformer, the oil-immersed transformer comprising an oil tank, a body, insulating oil and an outer insulation structure of the winding. The body is arranged in the oil tank, comprising an iron core and an outer peripheral winding of an iron core column which surrounds the iron core in sequence from the inside to the outside. Insulating oil is filled in the oil tank to provide a liquid immersion environment and liquid insulation for the body. The outer insulation structure of the winding comprises an iron core column insulation; the iron core column insulation is arranged between the iron core column of the iron core and the first winding; the iron core column insulation comprises a second insulating cylinder, an adjusting paperboard, and a fixed support bar which are arranged in sequence from the inside to the outside, wherein the material of the second insulating cylinder is an insulating material of Class B or above, and the material of the adjusting paperboard and the fixed support bar is an insulating material of Class A, so that the insulation of the entire iron core column meets the insulation requirements under high temperature. A mixed insulation structure is arranged on the winding; the material of the mixed insulation structure is obtained by combining insulating materials of Class B or above and insulating materials of Class A.

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

[0014] In some embodiments, the oil-immersed transformer further includes at least one oil pillow and at least one nitrogen tank. The oil pillow is arranged above the oil tank and is in communication with the oil pillow. The nitrogen tank is arranged outside the middle of the oil tank and is in communication with the oil pillow, and the nitrogen tank is filled with compressed nitrogen. In the vertical direction, the orthographic projection of the oil pillow and the orthographic projection of the nitrogen tank are both within the orthographic projection range of the oil tank.

[0015] In some embodiments, the nitrogen box is provided with an automatic pressure relief valve and a pressure sensor.

[0016] The oil-immersed transformer provided in the embodiment of the present invention has the same beneficial effects as the above insulation structure, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2 : A partial structural diagram of the body of an oil-immersed transformer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Embodiment 1:

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

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

[0023] Exemplarily, the above winding may be a layer winding or a pancake winding.

[0024] Class B insulation material refers to insulation material whose maximum allowable operating temperature is 130°C. Class A insulation material refers to insulation material whose maximum allowable operating temperature is 105°C.

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

[0026] Insulation materials of Class B or above can work at higher temperatures, so that the first insulation structure can provide normal insulation at the first position, improve the heat resistance of the first insulation structure, extend the life of the first insulation structure and thus the life of the winding, and improve the overload resistance of the winding. The material of the second insulation structure is Class A insulation material, so that the material cost of the second insulation structure can be reduced while providing insulation at the second position.

[0027] Therefore, the insulation structure provided by the embodiment of the present invention can improve the heat resistance of the first insulation structure while providing normal insulation at the first position by arranging the first insulation structure at the first position of the winding, and extend the life of the first insulation structure and thus extend the life of the winding by making the material of the first insulation structure adopt Class B or above insulation material; by arranging the second insulation structure at the second position of the winding and making the material of the second insulation structure adopt 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 insulation materials of the same grade, the insulation structure in the present invention uses insulation materials of different grades at different positions of the winding, which helps to reduce the cost of insulation materials on the winding while meeting the insulation requirements at different positions, thereby improving the economy of the oil-immersed transformer.

[0028] In some embodiments, the first insulating structure is used to achieve insulation at a first position of the winding, and the second insulating structure is used to achieve insulation at a second position of the winding. During the operation of the winding, the temperature of the second position is less than or equal to 105°C, and the temperature of 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, so the second insulation structure using 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, so the first insulation structure using 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 maintaining good insulation performance of the first insulation structure at the first position for a long time.

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

[0031] The interlayer insulation 13, the end insulation 15 and the oil passage adhesive paper can all be made of 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 end and the lower end of the layer winding.

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

[0033] The material of the first axial support bar 14 can be epoxy glass cloth rod of grade B or above, and is used to provide support and insulation between two adjacent layers of foil conductors 10 of the layer winding.

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

[0035] Through the above-mentioned arrangement, the interlayer insulation 13, the end insulation 15, the first axial support bar 14, the oil channel adhesive paper and the heat-resistant paper can have better insulation and heat resistance, thereby improving the service life of the interlayer insulation 13, the end insulation 15, the first axial support bar 14, the oil channel adhesive paper and the heat-resistant paper, and helping to maintain the insulation performance of the interlayer insulation 13, the end insulation 15, the first axial support bar 14, the oil channel adhesive paper and the heat-resistant paper for a long time.

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

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

[0038] The material of the second axial struts 16 may be cellulose.

[0039] Through the above arrangement, the second axial support bar 16 can provide insulation outside the layer winding, thereby reducing the material cost of the second axial support bar 16 .

[0040] In other embodiments, Figure 1 and Figure 2 As shown, the above winding is a pancake winding (such as Figure 2 The second winding 9 in the pancake winding is composed of a plurality of coils stacked on each other, and the coils are formed by winding the electromagnetic wire 11. The first insulating structure includes turn-to-turn insulation, which is arranged outside the electromagnetic wire 11 of the coil.

[0041] The inter-turn insulation may be an inter-turn wrapping paper made of DPE material, which is wrapped around the outside of the electromagnetic wire 11 to provide insulation on the outside of the electromagnetic wire 11 of the coil.

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

[0043] like Figure 2 As shown, the second insulating structure includes a first insulating cylinder 19, a plurality of inner support bars 20, a plurality of outer support bars 21, a plurality of radial oil passage pads 22, an insulating end ring 24 and a screen 25. The first insulating cylinder 19 is arranged around the inner side of the pancake winding. A plurality of inner support bars 20 are arranged between the first insulating cylinder 19 and the inner side of the pancake winding at intervals. A plurality of outer support bars 21 are arranged around the outer side of the pancake winding at intervals. A plurality of radial oil passage pads 22 are arranged between two adjacent coils at intervals to form radial oil passages between two adjacent coils. The insulating end ring 24 is arranged at the upper end and the lower end of the pancake winding. The screen 25 is arranged around the outer side of the plurality of outer support bars 21.

[0044] The materials of the first insulating tube 19, the plurality of inner stays 20, the plurality of outer stays 21, the plurality of radial oil passage gaskets 22, the insulating end rings 24 and the surrounding screen 25 may all be cellulose.

[0045] like Figure 2 As shown, the first insulating cylinder 19 is used in the pancake winding (such as Figure 2 The inner support bar 20 is used to provide support and insulation between the first insulating cylinder 19 and the inner side of the pancake winding. The outer support bar 21 is used to provide support and insulation on the outer side of the pancake winding. The radial oil passage pad 22 is used to provide support and insulation between two adjacent coils, so that the insulating oil in the transformer can flow in the radial oil passage to take away the heat on the coils. The insulating end ring 24 is used to provide insulation at the upper and lower ends of the pancake winding. The screen 25 is used to provide insulation on the outside of the outer support bar 21 and to provide protection for the outer support bar 21.

[0046] Through the above arrangement, the material costs of the first insulating tube 19, multiple inner support bars 20, multiple outer support bars 21, multiple radial oil channel gaskets 22, insulating end rings 24 and surrounding screens 25 can be reduced on the basis of providing insulation.

[0047] In some embodiments, Figure 2 As shown, the second insulating structure further includes a plurality of oil baffles 23; the oil baffles 23 are arranged between the outer side of the pancake winding and the surrounding 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 passage gasket 22 and the wire cake in contact with the radial oil passage gasket 22 .

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

[0050] The oil baffle 23 guides the insulating oil in the transformer, and can speed up the oil flow speed and efficiency, thereby reducing the hot spots and average temperature rise of the winding.

[0051] According to the simulated temperature field distribution and test data when the winding is working, the inventor found that the temperature rise value from the bottom to the top of the winding axial direction will increase evenly and gradually, such as gradually increasing from 15K to 60K; while the temperature rise in the radial direction does not change much, and the inside is higher than the outside. Therefore, in the high temperature zone (for example, the area with a temperature rise of 60K), B-level or above insulation materials are used. The high temperature zone can be a zone that is in direct contact with the conductor or in contact through turn insulation but has poor heat dissipation, a hot spot area, etc.; in the low temperature zone (for example, the area with a temperature rise of 15K), cellulose is used. The low temperature zone can be an oil channel with better heat dissipation or a main control channel area far away from the conductor, etc. The iron core column insulation between the iron core and the low voltage winding in the radial direction and the iron yoke insulation between the axial directions are respectively selected from mixed insulation and cellulose insulation. The low voltage winding, high voltage winding, and the main control channel insulation between high and low voltage are respectively selected from mixed insulation, mixed insulation and fiber insulation.

[0052] Embodiment 2:

[0053] like Figure 1 and Figure 2 As shown, an embodiment of the present invention also provides an oil-immersed transformer, which includes an oil tank 1, a body 27, insulating oil 6 and an outer insulation structure of the winding. The body 27 is arranged in the oil tank 1, including an iron core 7 and at least two windings that surround the outer periphery of the iron core column of the iron core 7 from the inside to the outside, wherein the 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 to provide a liquid immersion environment and liquid insulation for the body 27. The outer insulation structure of the winding includes an iron core column insulation 12. The iron core column insulation 12 is arranged between the iron core column of the iron core 7 and the first winding 8; the iron core column insulation 12 includes a second insulating cylinder, an adjusting paperboard, and a fixed support bar that are arranged in sequence from the inside to the outside, wherein the material of the second insulating cylinder is an insulating material of Class B or above, and the material of the adjusting paperboard and the fixed support bar is an insulating material of Class A, so that the insulation of the entire iron core column meets the insulation requirements at high temperatures. The first winding 8 is provided with the insulating structure in Example 1; the second winding 9 is provided with the insulating structure in Example 1.

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

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

[0056] For example, the number of windings surrounding the outer periphery of the core column of the core 7 may be two or three, etc. The winding may be a low voltage winding, a high voltage winding or a voltage regulating winding, etc., and the type of the winding may be a layer winding or a pancake winding.

[0057] For example, Figure 1 and Figure 2 In the embodiment, 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 insulating structure is immersed in the insulating oil 6, the heat resistance of the insulating structure can be improved, and the service life of various insulating materials in the insulating structure can be extended, thereby extending the insulation life of the oil-immersed transformer.

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

[0060] Exemplarily, the material of the second insulating tube is epoxy glass fiber, and the material of the adjusting cardboard and the fixing stay is cellulose.

[0061] Through the above arrangement, the epoxy glass fiber ensures the heat resistance of the second insulating tube, thereby improving the radial stress of the first winding 8 to resist sudden shorting; the above arrangement also reduces the material cost of the adjusting paperboard and the fixing stays.

[0062] The insulating oil 6 is filled in the winding and the insulating structure on the first winding 8 and the insulating structure on the second winding 9, thereby forming an insulation system of the oil-immersed transformer together with the insulating structure on the first winding 8 and the insulating structure on the second winding 9. 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.

[0063] Embodiment 3:

[0064] like Figure 1 and Figure 2As shown, an embodiment of the present invention also provides an oil-immersed transformer, which includes an oil tank 1, a body 27, insulating oil 6 and an outer insulation structure of the winding. The body 27 is arranged in the oil tank 1, including an iron core 7 and a winding that surrounds the outer periphery of the iron 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 body 27. The outer insulation structure of the winding includes an iron core column insulation 12. The iron core column insulation 12 is arranged between the iron core column of the iron core 7 and the first winding 8; the iron core column insulation 12 includes a second insulating cylinder, an adjusting paperboard, and a fixed support bar that are arranged in sequence from the inside to the outside, wherein the material of the second insulating cylinder is an insulating material of Class B or above, and the material of the adjusting paperboard and the fixed support bar is an insulating material of Class A, so that the insulation of the entire iron core column meets the insulation requirements under high temperature. The winding includes a mixed insulation structure; the material of the mixed insulation structure is obtained by combining insulating materials of Class B or above and Class A.

[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, thereby forming an insulation system of the oil-immersed transformer together 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, Figure 2 As shown, the winding outer insulation structure also includes a main control track insulation 18 and an iron yoke insulation 26. The main control track insulation 18 is arranged between the first winding 8 and the second winding 9, and the material of the main control track insulation 18 adopts Class A insulation material. The iron yoke insulation 26 is arranged between the iron yoke of the core 7 and the first winding 8 and the second winding 9, and the material of the iron yoke insulation 26 adopts Class A insulation material.

[0068] In some examples, such as Figure 2 As shown, in the direction from the first winding 8 to the second winding 9, the main control track insulation 18 includes insulating paperboard, stays and angle rings 17 arranged in sequence.

[0069] Exemplarily, the materials of the insulating paperboard, the stays and the corner rings 17 are all cellulose.

[0070] The insulating cardboard, support bars and corner rings 17 do not directly contact the conductor and the heating parts, and their temperature is similar to that of the insulating oil 6. Therefore, the use of cellulose material can meet the heat resistance requirements of the insulating cardboard, support bars and corner rings 17, which is beneficial to reduce the material cost of the insulating cardboard, support bars and corner rings 17.

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

[0072] The iron 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, the use of cellulose material can meet the heat resistance requirements between the iron yoke of the core 7 and the first winding 8 and the second winding 9, which is beneficial to reducing the material cost of the iron yoke insulation 26.

[0073] It should be noted that when assembling the oil-immersed transformer, the first winding 8 is first inserted into the second winding 9, and then inserted into the iron core 7 after the main control track insulation 18 and the iron 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 a K-grade flammable ester oil, and an economical natural ester with a flammable 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, degradable and environmentally friendly materials, which are beneficial to improving the environmental protection level of oil-immersed transformers. Natural ester oil and synthetic ester oil have high ignition point self-extinguishing properties, which improve the fire retardant ability of oil-immersed transformers. The maximum heat-resistant temperature of the insulation system of the oil-immersed transformer formed by natural ester oil or synthetic ester oil and the insulation structure in Example 1 is 20°C higher than the maximum heat-resistant temperature of the insulation system formed by ordinary mineral oil and heat-resistant paper, which improves the temperature rise limit, overload capacity and 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 channel 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 channel may 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 channel may be 5 mm; when the height of the first winding 8 is above 1000 mm, the thickness of the axial oil channel may be 6 mm.

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

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

[0081] Through the above arrangement, 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, Figure 1 As shown, the oil-immersed transformer also includes at least one oil pillow 2 and at least one nitrogen tank 3. The oil pillow 2 is arranged above the oil tank 1 and is connected to the oil pillow 2. The nitrogen tank 3 is arranged outside the middle of the oil tank 1 and is connected to the oil pillow 2. The nitrogen tank 3 is filled with compressed nitrogen. In the vertical direction, the orthographic projection of the oil pillow 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 oil pillows 2 and nitrogen boxes 3 can be set as needed. Figure 1 Two oil pillows 2 and two nitrogen boxes 3 are shown. The oil pillow 2 and the nitrogen box 3 can be fixed on the oil tank 1 by welding, and can also be detachably arranged on the oil tank 1 by fasteners.

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

[0085] For example, Figure 1 As shown, the two oil pillows 2 have the same shape and size. For example, the two oil pillows 2 are both rectangular in shape, and the two oil pillows 2 are arranged on opposite sides above the oil tank 1 to fully utilize the space above the oil tank 1, reduce the space occupied by the oil pillows 2, and facilitate the miniaturization of the oil-immersed transformer.

[0086] Exemplarily, the oil pillow 2 and the nitrogen tank 3 are connected via a first hose 4 .

[0087] The first hose 4 can be a PTFE hose, the outside of the PTFE hose is a 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 pillows 2 may be connected via a second hose 5 , and the second hose 5 may also be a PTFE hose.

[0089] The two oil pillows 2 and the two nitrogen tanks 3 are connected to each other through the first hose 4 and the second hose 5, and then connected to the inside of the oil tank 1 to form a closed chamber, which is filled with nitrogen. When the volume of the insulating oil 6 in the oil tank 1 changes due to temperature changes, the closed chamber can maintain the stability of the air pressure in the closed chamber without the need to set up a traditional desiccant and capsule structure, which is beneficial to reducing the volume occupied by the capsule and avoiding the high-frequency maintenance requirements of the desiccant and capsule of the traditional transformer, thereby achieving maintenance-free. The closed chamber can also keep the insulating oil 6 in the oil tank 1 isolated from the outside air, so that the insulating oil 6 and the insulating structure are protected from contamination by oxygen, water and impurities in the outside air, which is beneficial to reducing the aging and oxidation rate of the insulating oil 6 and the insulating structure, thereby increasing the life of the insulating oil 6 and the insulating structure, and increasing the life of the oil-immersed transformer.

[0090] It should be noted that before filling the nitrogen box 3 with nitrogen, the nitrogen box 3 needs to be evacuated and the sealing performance of the nitrogen box 3 needs to be tested.

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

[0092] In this way, the space occupied by the oil pillow 2 and the nitrogen box 3 can be reduced, which is conducive to the miniaturization of the oil-immersed transformer.

[0093] In some examples, the nitrogen tank 3 is provided with an automatic pressure relief valve 28 and a pressure sensor 29 .

[0094] When the nitrogen box 3 operates normally, the pressure inside it varies within a range of 0-45 kPa.

[0095] Exemplarily, the pressure relief action value of the automatic pressure relief valve 28 can be set to 40kPa-45kPa, for example, 45kPa. At this time, the action value of the pressure relief valve on the oil-immersed transformer can be set to 100kPa to avoid the pressure in the nitrogen tank 3 being too high and causing the pressure relief valve on the oil-immersed transformer to malfunction and protect the safety of the nitrogen tank 3.

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

[0097] Through the above arrangement, it is possible to avoid damage caused by excessive pressure in the nitrogen box 3, thereby improving the safety of the oil-immersed transformer.

[0098] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention 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 invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An insulating structure is provided on the winding of an oil-immersed transformer. It is characterized in that The insulating structure comprises: A first insulating structure is arranged at a first position of the winding, wherein the material of the first insulating structure is an insulating material of Class B or above; and, The second insulating structure is arranged at the second position of the winding, and the material of the second insulating structure is Class A insulating material.

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

3. The insulation structure according to claim 1, It is characterized in that The winding is a layer winding, which is formed by multiple layers of foil-type wires (10) wound from the inside to the outside; The first insulating structure comprises: Interlayer insulation (13) is arranged between two adjacent layers of foil-type conductors (10) of the layer winding; End insulation (15), arranged at the upper end and the lower end of the layer winding; A plurality of first axial struts (14) are fixed between two adjacent layers of foil-type conductors (10) of the layer winding by means of oil passage adhesive paper; an axial oil passage is formed between two adjacent first axial struts (14); and, Heat-resistant paper, coated on the outer side of the layer winding; The second insulating structure comprises a plurality of second axial struts (16); the plurality of second axial struts (16) are arranged outside the outermost interlayer insulation (13) of the layer winding and are arranged at intervals on the outer side of the heat-resistant paper.

4. The insulation structure according to claim 1, It is characterized in that The winding is a pancake-type winding, which is composed of a plurality of coils stacked on top of each other, and the coils are formed by winding electromagnetic wires (11); The first insulation structure comprises turn-to-turn insulation, and the turn-to-turn insulation is arranged outside the electromagnetic wire (11) of the coil; The second insulating structure comprises: A first insulating cylinder (19) is arranged around the inner side of the pancake winding; A plurality of inner support bars (20) are arranged at intervals between the first insulating cylinder (19) and the inner side of the pancake winding; A plurality of outer support bars (21) are spaced around the outer side of the pancake winding; A plurality of radial oil passage pads (22) are arranged at intervals between two adjacent coils to form radial oil passages between the two adjacent coils; Insulating end rings 24, disposed at the upper and lower ends of the pancake winding; and, The surrounding screen (25) is arranged around the outer sides of the plurality of outer support bars (21).

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

6. An oil-immersed transformer, It is characterized in that include: Fuel tank (1); A body (27) is arranged in the oil tank (1), comprising an iron core (7) and at least two windings which surround the outer periphery of the iron core column of the iron core (7) in sequence 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 device body (27); and, The winding outer insulation structure comprises an iron core column insulation (12); the iron core column insulation (12) is arranged between the iron core column of the iron core (7) and the first winding (8); the iron core column insulation (12) comprises a second insulation tube, an adjustment paper board, and a fixed support bar arranged in sequence from the inside to the outside, wherein the material of the second insulation tube is an insulation material of Class B or above, and the material of the adjustment paper board and the fixed support bar is an insulation material of Class A, so that the overall iron core column insulation meets the insulation requirements under high temperature; The first winding (8) is provided with an insulation structure according to any one of claims 1 to 5; the second winding (9) is provided with an insulation structure according to any one of claims 1 to 5.

7. An oil-immersed transformer, It is characterized in that include: Fuel tank (1); A body (27) is arranged in the oil tank (1), comprising an iron core (7) and at least two windings which surround the outer periphery of the iron core column of the iron core (7) in sequence 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 device body (27); and, The winding outer insulation structure comprises an iron core column insulation (12); the iron core column insulation (12) is arranged between the iron core column of the iron core (7) and the first winding (8); the iron core column insulation (12) comprises a second insulation tube, an adjustment paper board, and a fixed support bar arranged in sequence from the inside to the outside, wherein the material of the second insulation tube is an insulation material of Class B or above, and the material of the adjustment paper board and the fixed support bar is an insulation material of Class A, so that the overall iron core column insulation meets the insulation requirements under high temperature; The winding includes a mixed insulation structure; the material of the mixed insulation structure is obtained by combining insulation materials of Class B or above and insulation materials of Class A.

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

9. The oil-immersed transformer according to claim 6 or 7, It is characterized in that Also includes: at least one oil pillow (2), arranged above the oil tank (1) and connected to the oil pillow (2); and, at least one nitrogen box (3), which is arranged outside the middle of the oil tank (1) and is connected to the oil pillow (2), and the nitrogen box (3) is filled with compressed nitrogen; In the vertical direction, the orthographic projection of the oil pillow (2) and the orthographic projection of the nitrogen box (3) are both within the orthographic projection range of the oil tank (1).

10. The oil-immersed transformer according to claim 9, It is characterized in that The nitrogen box (3) is provided with an automatic pressure relief valve (28) and a pressure sensor (29).

Images