A low-voltage double-layer stacked winding structure and a transformer

Abstract

The present invention relates to the technical field of transformers, and particularly to a low-voltage double-layer winding structure and a transformer. The low-voltage double-layer winding structure includes an inner paper tube, an inner layer winding, a plurality of oil duct spacers, an insulating cylinder, and an outer layer winding; the plurality of oil duct spacers are arranged between the inner layer winding and the outer layer winding, and a lapping groove is formed in the surface of each oil duct spacer facing away from the inner layer winding along its own thickness direction. The insulating cylinder is lapped on the lapping grooves of the plurality of oil duct spacers, and the groove walls of the oil duct spacers corresponding to the lapping grooves are attached to the side surfaces of the insulating cylinder; the lapping grooves are arranged corresponding to the breakdown risk areas of the inner layer winding and the outer layer winding. The present invention effectively reduces the radial dimension of the outer layer winding, reduces the amount of wire used in the coil, and reduces the production cost, solving the technical problems of the existing double-layer winding structure that the radial dimension of the outer layer winding is too large, resulting in a large amount of wire used in the coil, high production cost, and the overall winding structure occupying a large space, resulting in an increase in the size of the transformer.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and particularly relates to a low-voltage double-layer winding structure and a transformer. Background Art

[0002] The double-layer winding is a widely used low-voltage winding structure, which is mainly composed of an inner winding and an outer winding, and both are usually continuously wound by the same wire. Under the action of electromagnetic induction, an electromotive force is induced in each turn of the winding. However, due to the different positions of each turn in the winding, the magnitudes of the induced electromotive forces are different, and the generated voltages are also different. Between the turns of the same winding, the voltage shows a gradient distribution along the axial direction of the winding. At this time, there will be an operating voltage difference between two symmetric points in the same radial direction of the inner winding and the outer winding, and the operating voltage differences between symmetric points at different positions gradually increase or gradually decrease along the axial direction of the winding. However, if the operating voltage difference reaches or exceeds 5 kV, and the insulation strength between the inner winding and the outer winding is insufficient, there is a risk of operating breakdown. At this time, in order to enhance the insulation strength between the windings, an insulating cylinder is set between the inner winding and the outer winding to improve the electrical isolation effect between the windings. On the other hand, in order to optimize the heat dissipation performance, the double-layer winding often adopts the design of using spacers to construct heat dissipation oil channels, so that the heat of the coil can be effectively carried out by the transformer oil flowing in the heat dissipation oil channels, and then the heat exchange with the external environment is realized, and the heat dissipation efficiency is improved.

[0003] In the existing double-layer winding, usually two layers of heat dissipation oil channels and an insulating cylinder are arranged between the inner winding and the outer winding. The winding structure is sequentially provided with an inner paper cylinder, an inner winding, an inner spacer, an insulating cylinder, an outer spacer, and an outer winding from the inside to the outside. However, the radial dimension of the outer winding of this double-layer winding structure is too large, resulting in a large amount of coil usage, high production cost, and the overall winding structure occupying a large space, resulting in an increase in the size of the transformer. Summary of the Invention

[0004] The main object of the present invention is to provide a low-voltage double-layer winding structure, which can simultaneously meet the requirements of electrical safety standards and the heat dissipation requirements of the winding, improve the space utilization rate, effectively reduce the radial dimension of the outer winding, the overall structure is reasonable and compact, occupies a small space, reduces the coil usage, reduces the production cost, and solves the technical problems that the radial dimension of the outer winding of the existing double-layer winding structure is too large, resulting in a large amount of coil usage, high production cost, and the overall winding structure occupying a large space, resulting in an increase in the size of the transformer.

[0005] Another object of the present invention is to provide a transformer using the above-mentioned low-voltage double-layered winding structure, which can effectively reduce the size of the transformer, reduce the production cost, and solve the technical problems that the radial size of the outer winding of the existing double-layered winding structure is too large, resulting in a large amount of coil usage, high production cost, and the overall winding structure occupying a large space, resulting in an increase in the size of the transformer.

[0006] To achieve the above object, the low-voltage double-layered winding structure proposed by the present invention is applied to a transformer and includes an inner paper tube, an inner layer winding, a plurality of oil duct spacers, an insulating cylinder, and an outer layer winding;

[0007] The inner layer winding is disposed around the inner paper tube, the outer layer winding is disposed on a side of the inner layer winding away from the inner paper tube, the insulating cylinder is provided on a side of the outer layer winding close to the inner paper tube, and a plurality of the oil duct spacers are disposed between the inner layer winding and the outer layer winding. Each of the oil duct spacers extends along the axial direction of the inner paper tube to form a layer of heat dissipation oil duct between the inner layer winding and the outer layer winding;

[0008] A lapping groove is formed on a side of each of the oil duct spacers facing away from the inner layer winding along its own thickness direction. The height of the insulating cylinder is adapted to the length of the lapping groove. The insulating cylinder is lapped on the lapping grooves of the plurality of oil duct spacers, and the groove walls of the oil duct spacers corresponding to the lapping grooves are in contact with the side surfaces of the insulating cylinder;

[0009] Both the inner layer winding and the outer layer winding include a non-breakdown risk area and a breakdown risk area, and the lapping groove is provided corresponding to the breakdown risk area of the inner layer winding and the breakdown risk area of the outer layer winding.

[0010] Optionally, the height of the insulating cylinder is half of the height of the inner paper tube, and the length of the oil duct spacer is the same as the height of the inner paper tube.

[0011] Optionally, the plurality of oil duct spacers have the same thickness, and the oil duct spacers are uniformly arranged along the circumferential direction of the inner layer winding.

[0012] Optionally, the thickness dimension of the oil duct spacer is 4 mm - 8 mm.

[0013] Optionally, the thickness dimension of the oil duct spacer is 6 mm.

[0014] Optionally, the depth of the lapping groove is greater than or equal to the thickness of the insulating cylinder.

[0015] Optionally, the thickness of the insulating cylinder is 1.5 mm - 2 mm.

[0016] Optionally, the height of the inner paper tube = the winding height of the inner layer winding + the insulation height of the upper end of the inner layer winding + the insulation height of the lower end of the inner layer winding; the insulation height of the upper end of the inner layer winding is the distance between the upper end face of the inner layer winding and the upper end face of the oil duct support bar; the insulation height of the lower end of the inner layer winding is the distance between the lower end face of the inner layer winding and the lower end face of the oil duct support bar;

[0017] Or, the height of the inner paper tube = the winding height of the outer layer winding + the insulation height of the upper end of the outer layer winding + the insulation height of the lower end of the outer layer winding; the insulation height of the upper end of the outer layer winding is the distance between the upper end face of the outer layer winding and the upper end face of the oil duct support bar; the insulation height of the lower end of the outer layer winding is the distance between the lower end face of the outer layer winding and the lower end face of the oil duct support bar.

[0018] The present invention also provides a transformer, including the low-voltage double-layered winding structure according to any one of the above.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In this low-voltage double-layered winding structure, both the inner layer winding and the outer layer winding include a non-breakdown risk area and a breakdown risk area. According to the voltage gradient distribution characteristics of the layered winding, a lapping groove is opened along the thickness direction of each oil duct support bar on the side facing away from the inner layer winding. By correspondingly setting lapping grooves in the two breakdown risk areas, an oil duct support bar and an insulating cylinder are provided between the breakdown risk area of the inner layer winding and the breakdown risk area of the outer layer winding. The insulating cylinder is used to protect the two breakdown risk areas, effectively improving the insulation strength between them and avoiding the occurrence of breakdown during operation; and since the insulation strength between the non-breakdown risk area of the inner layer winding and the non-breakdown risk area of the outer layer winding has reached the requirements of the electrical safety standard and no breakdown will occur during operation, no insulating cylinder is provided between these two non-breakdown risk areas, and only an oil duct support bar is provided. The overall insulation strength of this low-voltage double-layered winding structure is high, meeting the requirements of the electrical safety standard and can operate safely.

[0021] 2. In this low-voltage double-layered winding structure, the oil duct support bar is locally grooved, and the two breakdown risk areas correspond to the lapping grooves, while the oil duct support bars corresponding to the two non-breakdown risk areas are not grooved. Therefore, the oil duct support bars corresponding to the two non-breakdown risk areas have a larger thickness, which can further increase the thickness of the heat dissipation oil duct and improve the overall heat dissipation performance, ensuring that the heat dissipation requirements between the inner layer winding and the outer layer winding can be met. Therefore, this low-voltage double-layered winding structure can meet both the requirements of the electrical safety standard and the winding heat dissipation requirements.

[0022] 3. In addition, by making local grooving on the oil duct support bars, a lapping groove with a certain depth can be used to place the insulating cylinder, so that the insulating cylinder does not occupy an extra layer of space, effectively improving the space utilization rate. With this low-voltage double-layer winding structure, the coils can be arranged more closely during the layer-by-layer winding process, effectively reducing the radial dimension of the outer winding. This low-voltage double-layer winding structure has the characteristics of a reasonable and compact overall structure, small space occupation, and high short-circuit resistance. Moreover, reducing the radial dimension of the outer winding can reduce the amount of coils used, reduce the consumption of raw materials, thereby reducing production costs and having better economy. Therefore, this low-voltage double-layer winding structure takes into account economy, electrical safety, and heat dissipation performance at the same time.

[0023] 4. In addition, in the existing winding structure, one layer of heat dissipation oil ducts corresponds to one winding, that is, one layer of heat dissipation oil ducts can only be used to achieve the heat dissipation of one winding. However, this low-voltage double-layer winding structure uses one layer of heat dissipation oil ducts to achieve the simultaneous heat dissipation of the inner winding and the outer winding. Therefore, this low-voltage double-layer winding structure also has the advantage of high heat dissipation utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the top view of the low-voltage double-layer winding structure according to an embodiment of the present invention;

[0025] Figure 2 is Figure 1 the enlarged view of part A in

[0026] Figure 3 is Figure 1 the schematic structural view after hiding the outer winding;

[0027] Figure 4 is the schematic structural view of the oil duct support bar of the low-voltage double-layer winding structure according to an embodiment of the present invention;

[0028] Figure 5 is Figure 3 the front view after hiding the insulating cylinder;

[0029] Figure 6 is the schematic structural view of the insulating cylinder and the oil duct support bar of the low-voltage double-layer winding structure according to an embodiment of the present invention;

[0030] Figure 7 is the schematic diagram of the principle of the low-voltage double-layer winding structure according to an embodiment of the present invention;

[0031] Figure 8 is the schematic diagram of the principle of the existing winding structure.

[0032] Wherein: 1. Inner paper tube; 2. Inner layer winding; 3. Oil duct support bar; 31. Lapping groove; 4. Insulating cylinder; 5. Outer layer winding; 6. Heat dissipation oil duct; 61. Oil duct partition area; 7. Non-breakdown risk area; 8. Breakdown risk area; 3a. Inner support bar; 3b. Outer support bar; 4a. Insulating board. Detailed implementation manner

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] It should be noted that all the directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0035] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution that satisfies both A and B at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions appears to be contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0037] The present invention proposes a low-voltage double-layer laminated winding structure.

[0038] In the embodiments of the present invention, as Figures 1 to 6As shown in the figure, this low-voltage double-layered winding structure is applied to a transformer, including an inner paper cylinder 1, an inner layer winding 2, several oil duct support bars 3, an insulating cylinder 4, and an outer layer winding 5;

[0039] The inner layer winding 2 is arranged around the inner paper cylinder 1. The outer layer winding 5 is arranged on the side of the inner layer winding 2 away from the inner paper cylinder 1. An insulating cylinder 4 is provided on the side of the outer layer winding 5 close to the inner paper cylinder 1. Several oil duct support bars 3 are arranged between the inner layer winding 2 and the outer layer winding 5. Each oil duct support bar 3 extends along the axial direction of the inner paper cylinder 1 to form a layer of heat dissipation oil duct 6 between the inner layer winding 2 and the outer layer winding 5;

[0040] On the side of each oil duct support bar 3 facing away from the inner layer winding 2, a lapping groove 31 is opened along its own thickness direction. The height of the insulating cylinder 4 is adapted to the length of the lapping groove 31. The insulating cylinder 4 is lapped on the lapping grooves 31 of several oil duct support bars 3, and the groove wall of the oil duct support bar 3 corresponding to the lapping groove 31 is in contact with the side surface of the insulating cylinder 4;

[0041] Both the inner layer winding 2 and the outer layer winding 5 include a non-breakdown risk area 7 and a breakdown risk area 8. The lapping groove 31 is arranged corresponding to the breakdown risk area 8 of the inner layer winding 2 and the breakdown risk area 8 of the outer layer winding 5.

[0042] In this low-voltage double-layered winding structure, both the inner layer winding 2 and the outer layer winding 5 include a non-breakdown risk area 7 and a breakdown risk area 8. According to the voltage gradient distribution characteristics of the layered winding, on the side of each oil duct support bar 3 facing away from the inner layer winding 2, a lapping groove 31 is opened along its own thickness direction. By arranging the lapping grooves 31 corresponding to the two breakdown risk areas 8, an oil duct support bar 3 and an insulating cylinder 4 are arranged between the breakdown risk area 8 of the inner layer winding 2 and the breakdown risk area 8 of the outer layer winding 5. The insulating cylinder 4 is used to protect the two breakdown risk areas 8, effectively improving the insulation strength between them and avoiding the occurrence of operating breakdown; and since the insulation strength between the non-breakdown risk area 7 of the inner layer winding 2 and the non-breakdown risk area 7 of the outer layer winding 5 has reached the requirements of the electrical safety standard and no operating breakdown will occur, no insulating cylinder is arranged between these two non-breakdown risk areas 7, and only the oil duct support bar 3 is arranged. The overall insulation strength of this low-voltage double-layered winding structure is high, meeting the requirements of the electrical safety standard and can operate safely.

[0043] In this low-voltage double-layered winding structure, the oil duct support bar 3 is subjected to local grooving treatment. The two breakdown risk areas 8 correspond to the lapping grooves 31, while the oil duct support bars 3 corresponding to the two non-breakdown risk areas 7 are not grooved. Therefore, the oil duct support bars 3 corresponding to the two non-breakdown risk areas 7 have a larger thickness, which can further increase the thickness of the heat dissipation oil duct 6 and improve the overall heat dissipation performance, ensuring that the heat dissipation requirements between the inner layer winding 2 and the outer layer winding 5 can be met. Therefore, this low-voltage double-layered winding structure can meet the requirements of the electrical safety standard and the winding heat dissipation requirements at the same time.

[0044] In addition, by making partial slotting treatment on the oil duct support bar 3, the overlapping slot 31 with a certain depth can be used to place the insulating cylinder 4, so that the insulating cylinder 4 does not additionally occupy an extra layer of space, effectively improving the space utilization rate. With this low-voltage double-layer winding structure, the coils can be arranged more closely during the layer-by-layer winding process, effectively reducing the radial dimension of the outer winding 5. This low-voltage double-layer winding structure has the characteristics of reasonable and compact overall structure, small space occupation, and high short-circuit resistance. Moreover, reducing the radial dimension of the outer winding 5 can reduce the amount of coils used, reduce the consumption of raw materials, thereby reducing the production cost and having better economy. Therefore, this low-voltage double-layer winding structure takes into account economy, electrical safety, and heat dissipation performance at the same time.

[0045] In addition, in the existing winding structure, one layer of cooling oil ducts corresponds to one winding, that is, one layer of cooling oil ducts can only be used to cool one winding. However, in this low-voltage double-layer winding structure, one layer of cooling oil ducts 6 can be used to cool the inner winding 2 and the outer winding 5 simultaneously. Therefore, this low-voltage double-layer winding structure also has the advantage of high heat dissipation utilization rate.

[0046] This low-voltage double-layer winding structure solves the technical problems of the existing double-layer winding structure, where the radial dimension of the outer winding is too large, resulting in a large amount of coils used, high production cost, and the overall winding structure occupying a large space, leading to an increase in the size of the transformer.

[0047] To be able to understand the present invention more easily, an example is given here in combination with Figure 7 and Figure 8 In the low-voltage double-layer winding structure of the present invention, as shown in Figure 7 , the thickness of the oil duct support bar 3 is 6 mm, the thickness of the overlapping slot 31 is 1.5 mm, and the thickness of the insulating cylinder 4 is also 1.5 mm. At this time, the breakdown risk areas 8 of the inner winding 2 and the outer winding 5 correspond to the 1.5-mm insulating cylinder 4 and the 4.5-mm oil duct support bar 3, and the non-breakdown risk areas 7 of the inner winding 2 and the outer winding 5 correspond to the 6-mm oil duct support bar 3. Therefore, the thickness of the cooling oil duct 6 between the inner winding 2 and the outer winding 5 is 6 mm. As shown in Figure 8As shown, in the existing winding structure, inner layer braces 3a, outer layer braces 3b and insulating plates 4a (equivalent to insulating cylinders 4) are arranged between the inner layer winding 2 and the outer layer winding 5. Assuming that the thickness of both the inner layer braces 3a and the outer layer braces 3b is 5 mm and the thickness of the insulating plate 4a is 1.5 mm, then the thickness between the inner layer winding 2 and the outer layer winding 5 is 11.5 mm, which is greater than the 6 mm thickness of the present invention. Therefore, the radial dimension of the outer layer winding 5 in the existing winding structure is large, the coil consumption is large, the economy is poor, the compactness of coil winding is not good, and the short-circuit resistance is low. However, the present invention can reduce the radial dimension of the outer layer winding 5, reduce the coil consumption, have better economy, make the coil winding more compact and have high short-circuit resistance.

[0048] Further explanation: The oil duct braces 3 corresponding to the non-breakdown risk areas 7 of the inner layer winding 2 and the outer layer winding 5 are arranged between the inner layer winding 2 and the outer layer winding 5. At this time, the heat dissipation oil ducts 6 corresponding to the non-breakdown risk areas 7 of the inner layer winding 2 and the outer layer winding 5 are arranged between the inner layer winding 2 and the outer layer winding 5.

[0049] The oil duct braces 3 corresponding to the breakdown risk areas 8 of the inner layer winding 2 and the outer layer winding 5 are arranged between the inner layer winding 2 and the insulating cylinder 4. At this time, the heat dissipation oil ducts 6 corresponding to the breakdown risk areas 8 of the inner layer winding 2 and the outer layer winding 5 are arranged between the insulating cylinder 4 and the inner layer winding 2.

[0050] Further explanation: The non-breakdown risk area 7 is the area where the operating voltage difference between two symmetric points in the same radial direction of the inner layer winding 2 and the outer layer winding 5 is < 5 kV. Only the oil duct braces 3 are correspondingly arranged in this area. The breakdown risk area 8 is the area where the operating voltage difference between two symmetric points in the same radial direction of the inner layer winding 2 and the outer layer winding 5 is ≥ 5 kV. The oil duct braces 3 and the insulating cylinder 4 are correspondingly arranged in this area. The inner layer winding 2 and the outer layer winding 5 are continuously wound with the same wire, and the winding directions between the inner layer winding ② and the outer layer winding ⑤ are opposite.

[0051] Further explanation: This low-voltage double-layer winding structure is used in the voltage range of 3 kV - 35 kV.

[0052] Preferably, the winding height of the inner layer winding 2 is the same as the winding height of the outer layer winding 5.

[0053] As Figure 3 、 5 As shown in FIGS. 5 and 6, in an embodiment of the present application, the height of the insulating cylinder 4 is half of the height of the inner paper cylinder 1, and the length of the oil duct brace 3 is the same as the height of the inner paper cylinder 1.

[0054] According to the characteristic that the turn voltage in the layer winding shows a gradient distribution along the axial direction of the winding, the height of the insulating cylinder 4 is set to half of the height of the inner paper cylinder 1. In this way, the insulating cylinder 4 can protect the two breakdown risk areas 8, improve the insulation strength, and ensure meeting the requirements of the electrical safety standard; for the two non-breakdown risk areas 7, only the oil duct spacers 3 are correspondingly arranged. At this time, half of the length of the oil duct spacers 3 is not grooved, so this part of the oil duct spacers 3 still has a relatively high thickness, thereby increasing the thickness of the cooling oil ducts 6 corresponding to the two non-breakdown risk areas 7 as much as possible and improving the overall heat dissipation performance. Therefore, this low-voltage double-layer layer winding structure not only ensures meeting the winding heat dissipation requirements and the electrical safety standard, but also can simplify the design of this low-voltage double-layer layer winding structure and the transformer applying this low-voltage double-layer layer winding structure, reduce the design complexity, facilitate the standardized design, and help improve the production and assembly efficiency. When the length of the oil duct spacers 3 is the same as the height of the inner paper cylinder 1, the mechanical strength of this low-voltage double-layer layer winding structure can be improved, preventing it from deforming or being damaged when subjected to external forces.

[0055] Furthermore, the inner winding 2 and the outer winding 5 are symmetrically arranged with each other. As Figure 7 shown, the difference between the voltage at the midpoint C of the inner winding 2 and the voltage at the midpoint D of the outer winding 5 is half of the difference between the voltage at point A of the inner winding 2 and the voltage at point X of the outer winding 5.

[0056] As Figure 7As shown, taking the 10 kV corner-connected low-voltage winding as an example, the voltage at point A is 0 kV, the voltage at point X is 10 kV, and the operating voltage difference between the two is 10 kV. The operating voltage difference between the middle position point C of the inner layer winding 2 and the middle position point D of the outer layer winding 5 is 5 kV, and the operating voltage difference gradually decreases from left to right. At this time, the breakdown risk area 8 of the inner layer winding 2 is the A-C area, and the breakdown risk area 8 of the outer layer winding 5 is the X-D area. Oil duct supports 3 and insulating cylinders 4 are correspondingly arranged between the A-C area and the X-D area. That is, the part with a high voltage difference is protected by a local insulating cylinder 4 to ensure the insulation strength and balance economy and heat dissipation performance. The area where the operating voltage difference < 5 kV is the non-breakdown risk area 7. At this time, the non-breakdown risk area 7 of the inner layer winding 2 is the C-E area, and the non-breakdown risk area 7 of the outer layer winding 5 is the D-F area. Only oil duct supports 3 are correspondingly arranged between the C-E area and the D-F area. This is because the insulation strength of this part has reached the requirements of the electrical safety standard and does not require covering insulation with an insulating cylinder 4. Moreover, the oil duct supports 3 corresponding to the two non-breakdown risk areas 7 have a large thickness, and the thickness of the heat dissipation oil duct 6 is increased as much as possible in the part with a low voltage difference to increase the heat dissipation surface and improve the heat dissipation performance. This low-voltage double-layer winding structure can cleverly utilize the different operating voltage differences at each part during the operation of the winding, increase the heat dissipation surface as much as possible in the part with a low voltage difference, and use a local insulating cylinder 4 for protection in the part with a high voltage difference, which can balance economy and heat dissipation.

[0057] As Figure 1 and 5 shown, in an embodiment of the present application, the thicknesses of several oil duct supports 3 are the same, and the oil duct supports 3 are evenly arranged along the circumferential direction of the inner layer winding 2.

[0058] Several oil duct supports 3 with the same thickness and evenly arranged along the circumferential direction of the inner layer winding 2 form an oil duct separation area 61 between adjacent two oil duct supports 3. Each oil duct separation area 61 has a uniform size, and several oil duct separation areas 61 together form a layer of heat dissipation oil duct 6. The transformer oil flows evenly, thereby effectively improving the heat dissipation efficiency, ensuring the same insulation distance between the inner layer winding 2 and the outer layer winding 5, reducing the risk of electrical breakdown, and enhancing the structural stability of this low-voltage double-layer winding structure.

[0059] Specifically, the cross-sectional shape of the oil duct support 3 is rectangular.

[0060] In an embodiment of the present application, the thickness dimension of the oil duct support 3 is 4 mm - 8 mm.

[0061] The oil duct support strip 3 with a thickness dimension of 4 mm - 8 mm can ensure that the heat dissipation requirements of the inner winding 2 and the outer winding 5 are met, enabling the low-voltage double-layer winding structure to have good heat dissipation performance. At the same time, it reduces the electrical interference between the inner winding 2 and the outer winding 5 and can also ensure the overall mechanical strength of the low-voltage double-layer winding structure.

[0062] In an embodiment of the present application, the thickness dimension of the oil duct support strip 3 is 6 mm.

[0063] When the thickness dimension of the oil duct support strip 3 is 6 mm, a heat dissipation oil duct 6 with a suitable thickness can be formed between the inner winding 2 and the outer winding 5 at this time, effectively dissipating the heat of the inner winding 2 and the outer winding 5, enabling the low-voltage double-layer winding structure to have high heat dissipation performance, and also providing stronger support force for the low-voltage double-layer winding structure to ensure the stability of the overall structure. By using the oil duct support strip 3 with a thickness of 6 mm, the heat dissipation requirements of the inner winding 2 and the outer winding 5 can be met, ensuring the safe operation of the low-voltage double-layer winding structure. According to the different operating pressure differences at each part during the operation of the inner winding 2 and the outer winding 5, the area with a low pressure difference (<5 kV) is the non-breakdown risk area 7, and the oil duct support strip 3 is correspondingly arranged in the two non-breakdown risk areas 7. The thickness of the heat dissipation oil duct 6 is increased as much as possible in this area to improve the heat dissipation performance. The area with a high pressure difference (≥5 kV) is the breakdown risk area 8, and this area is protected by the insulating cylinder 4. The oil duct support strip 3 and the insulating cylinder 4 are correspondingly arranged in the two breakdown risk areas 8 to improve the insulation strength and ensure meeting the requirements of the electrical safety standard. Therefore, the low-voltage double-layer winding structure takes into account heat dissipation performance, electrical safety, and cost, and can meet the electrical safety standard and the winding heat dissipation requirements at the same time.

[0064] Such as Figure 2 and 3 shown, in an embodiment of the present application, the depth of the lapping groove 31 is greater than or equal to the thickness of the insulating cylinder 4.

[0065] The depth of the lapping groove 31 being greater than or equal to the thickness of the insulating cylinder 4 can ensure that the insulating cylinder 4 can be completely lapped on the lapping groove 31, and further ensure that a good insulation effect can be achieved between the two breakdown risk areas 8 corresponding to the insulating cylinder 4, meeting the requirements of the electrical safety standard.

[0066] In an embodiment of the present application, the thickness of the insulating cylinder 4 is 1.5 mm - 2 mm.

[0067] Setting the thickness of the insulating cylinder 4 to 1.5 mm - 2 mm can ensure that the insulating cylinder 4 can provide necessary electrical isolation and enhance the overall insulation performance.

[0068] For example, in an embodiment of the present invention, the thickness of the insulating cylinder 4 is 1.5 mm, and the depth of the overlapping groove 31 is 1.5 mm. At this time, the thickness of the oil duct support 3 corresponding to the non-breakdown risk area 7 is 6 mm, and the thickness of the oil duct support 3 corresponding to the breakdown risk area 8 is 4.5 mm.

[0069] In an embodiment of the present application, the height of the inner paper cylinder 1 = the winding height of the inner layer winding 2 + the insulation height of the upper end of the inner layer winding 2 + the insulation height of the lower end of the inner layer winding 2; the insulation height of the upper end of the inner layer winding 2 is the distance between the upper end face of the inner layer winding 2 and the upper end face of the oil duct support 3; the insulation height of the lower end of the inner layer winding 2 is the distance between the lower end face of the inner layer winding 2 and the lower end face of the oil duct support 3;

[0070] Or, the height of the inner paper cylinder 1 = the winding height of the outer layer winding 5 + the insulation height of the upper end of the outer layer winding 5 + the insulation height of the lower end of the outer layer winding 5; the insulation height of the upper end of the outer layer winding 5 is the distance between the upper end face of the outer layer winding 5 and the upper end face of the oil duct support 3; the insulation height of the lower end of the outer layer winding 5 is the distance between the lower end face of the outer layer winding 5 and the lower end face of the oil duct support 3.

[0071] The inner paper cylinder 1 with an appropriate height can not only provide necessary support for this low-voltage double-layer winding structure, improve the overall structural strength, help maintain the structural stability and enhance the electrical isolation effect, but also improve the heat dissipation effect of this low-voltage double-layer winding structure.

[0072] In the present invention, the minimum limit values of the end insulation height are set for different operating voltages:

[0073] Under the operating voltage of 10 kV and below 10 kV, the minimum limit values of the insulation height of the upper end of the inner layer winding 2, the insulation height of the lower end of the inner layer winding 2, the insulation height of the upper end of the outer layer winding 5, and the insulation height of the lower end of the outer layer winding 5 are all 10 mm;

[0074] Under the operating voltage of 20 kV, the minimum limit values of the insulation height of the upper end of the inner layer winding 2, the insulation height of the lower end of the inner layer winding 2, the insulation height of the upper end of the outer layer winding 5, and the insulation height of the lower end of the outer layer winding 5 are all 15 mm;

[0075] Under the operating voltage of 35 kV, the minimum limit values of the insulation height of the upper end of the inner layer winding 2, the insulation height of the lower end of the inner layer winding 2, the insulation height of the upper end of the outer layer winding 5, and the insulation height of the lower end of the outer layer winding 5 are all 20 mm. It should be noted that these are only the minimum standards, and the actual end insulation height can be flexibly designed according to specific circumstances, which is not limited here.

[0076] The present invention provides a transformer, including the low-voltage double-layer winding structure of any one of the above.

[0077] By using this low-voltage double-layer winding structure, the radial dimension of the outer winding 5 can be effectively reduced. The overall structure of this low-voltage double-layer winding structure is reasonable and compact, with small space occupation, so that the size of the transformer can be effectively reduced, the production cost can be effectively reduced, and the economy is better. It solves the technical problem that the radial dimension of the outer winding 5 of the existing double-layer winding structure is too large, resulting in an increase in the size of the transformer.

[0078] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A low-voltage double-layer laminated winding structure, applied to a transformer, characterized in that, It includes an inner paper tube, an inner winding, several oil channel stays, an insulating tube and an outer winding; The inner layer winding is arranged around the inner paper tube, the outer layer winding is arranged on the side of the inner layer winding away from the inner paper tube, and the insulating tube is provided on the side of the outer layer winding close to the inner paper tube. The inner layer winding and the outer layer winding both include a non-breakdown risk area and a breakdown risk area. The oil channel struts corresponding to the non-breakdown risk area of the inner layer winding and the non-breakdown risk area of the outer layer winding are arranged between the inner layer winding and the outer layer winding. The oil channel struts corresponding to the breakdown risk area of the inner layer winding and the breakdown risk area of the outer layer winding are arranged between the inner layer winding and the insulating tube. Each of the oil channel struts extends along the axial direction of the inner paper tube to form a layer of heat dissipation oil channel between the inner layer winding and the outer layer winding. Each of the oil channel struts has a lap groove formed along its thickness direction on a side facing away from the inner layer winding. The height of the insulating tube matches the length of the lap groove. The insulating tube overlaps the lap grooves of the plurality of oil channel struts, and the groove wall of the oil channel strut corresponding to the lap groove fits in contact with the side surface of the insulating tube. The overlapping grooves are provided corresponding to the breakdown risk area of the inner winding and the breakdown risk area of the outer winding.

2. The low-voltage double-layer laminated winding structure according to claim 1, characterized in that, The height of the insulating tube is half of the height of the inner paper tube, and the length of the oil channel support bar is the same as the height of the inner paper tube.

3. The low-voltage double-layer laminated winding structure according to claim 2, characterized in that The plurality of oil channel struts have the same thickness, and are evenly arranged along the circumference of the inner layer winding.

4. The low-voltage double-layer laminated winding structure according to claim 3, characterized in that, The thickness of the oil channel support strip is 4mm-8mm.

5. The low-voltage double-layer laminated winding structure according to claim 4, wherein, The thickness of the oil channel support bar is 6 mm.

6. The low-voltage double-layer laminated winding structure according to claim 1, wherein The depth of the overlapping groove is greater than or equal to the thickness of the insulating tube.

7. The low-voltage double-layer laminated winding structure according to claim 6, characterized in that The thickness of the insulating tube is 1.5 mm to 2 mm.

8. The low-voltage double-layer stacked winding structure according to claim 7, wherein, The height of the inner paper tube = the winding height of the inner winding + the insulation height of the upper end of the inner winding + the insulation height of the lower end of the inner winding; the insulation height of the upper end of the inner winding is the distance between the upper end surface of the inner winding and the upper end surface of the oil channel support; the insulation height of the lower end of the inner winding is the distance between the lower end surface of the inner winding and the lower end surface of the oil channel support; Or, the height of the inner paper tube = the winding height of the outer winding + the insulation height of the upper end of the outer winding + the insulation height of the lower end of the outer winding; the insulation height of the upper end of the outer winding is the distance between the upper end surface of the outer winding and the upper end surface of the oil channel support; the insulation height of the lower end of the outer winding is the distance between the lower end surface of the outer winding and the lower end surface of the oil channel support.

9. A transformer, characterized in that, It comprises the low-voltage double-layer winding structure as described in any one of claims 1 to 8.

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