A 110kV three-phase dry-type transformer

Abstract

This application relates to the field of power transformer technology, specifically to a 110kV three-phase dry-type transformer. This 110kV three-phase dry-type transformer includes three parallel core columns and two side columns on either side of the three core columns. An upper yoke is positioned above the core columns and side columns, and a lower yoke is positioned below them. Each core column houses a low-voltage coil and a high-voltage coil from the inside out. The three sets of low-voltage coils and three sets of high-voltage coils respectively form a three-phase low-voltage winding and a three-phase high-voltage winding. The high-voltage coil is a multi-segment layered coil with inlet wires at the top and outlet wires at the bottom, while the low-voltage coil is a layered coil with inlet wires at the ends. The upper air gap D between the upper end of the high-voltage coil and the upper yoke is greater than the lower air gap d between the lower end of the high-voltage coil and the lower yoke, thus forming a graded insulation structure. By using a three-phase five-column core structure, the overall height of the transformer is reduced, thus resolving the contradiction between insulation performance requirements and size / height limitations in existing technologies while ensuring electrical performance.

Description

Technical Field

[0001] This application relates to the field of power transformer technology, and more specifically, to a 110kV three-phase dry-type transformer. Background Technology

[0002] There are two main structural types of existing 110kV three-phase dry-type transformers.

[0003] One option is a three-phase transformer consisting of three single-phase transformers, with the 110kV high-voltage coil's input terminal located in the middle of the high-voltage coil. The middle input terminal of the high-voltage coil can better meet the insulation requirements for lightning strikes and other electrical surges. However, it suffers from problems such as large footprint, low operating performance and efficiency, and poor reliability. Three-phase integrated iron-core 110kV dry-type transformers are the mainstream equipment in the 110kV power distribution field, with advantages of high economy, high safety, and low maintenance costs. They are particularly suitable for urban power distribution networks, industrial parks, high-rise buildings, and other scenarios with specific requirements for equipment space, fire prevention, and low maintenance. However, current three-phase integrated iron-core 110kV dry-type transformers generally suffer from large geometric dimensions and transportation difficulties.

[0004] For example, if a high-voltage coil with a high-voltage inlet structure is used, the creepage distance between the high-voltage coil inlet and outlet ends needs to be doubled, and the overall height of the transformer will greatly exceed the 4.6m limit for vehicle transportation. If a high-voltage coil with a high-voltage inlet structure is used, the larger creepage distance between the high-voltage coil inlet and outlet ends, as well as the increased air insulation distance at the end caused by the high-voltage inlet, will also cause the overall height of the transformer to exceed the 4.6m limit for vehicle transportation. Utility Model Content

[0005] This application provides a 110kV three-phase integrated iron-core dry-type transformer, which can solve the problems of existing three-phase integrated dry-type transformers at the 110kV voltage level, where the insulation level requirements cause the transformer height to exceed the height limit for automobile transportation, and the contradiction between the transformer's withstand voltage insulation capacity and its size and height.

[0006] The 110kV three-phase dry-type transformer provided in this application includes a three-phase five-limb iron core; The three-phase five-column iron core includes three core columns arranged in parallel, and two side columns arranged on both sides of the three core columns; an upper yoke is provided above the core columns and the side columns, and a lower yoke is provided below them; Each core column is fitted with a low-voltage coil and a high-voltage coil from the inside out. The three sets of low-voltage coils and the three sets of high-voltage coils respectively form a three-phase low-voltage winding and a three-phase high-voltage winding. The high-voltage coil is a multi-segment layered coil with wires entering at the top and exiting at the bottom, and the low-voltage coil is a layered coil with wires entering and exiting at the ends. The upper spacing D between the upper end of the high-voltage coil and the upper yoke is greater than the lower spacing d between the lower end of the high-voltage coil and the lower yoke, thus forming a graded insulation structure.

[0007] In a preferred embodiment, the upper spacing D ranges from 400mm to 500mm, and the lower spacing d ranges from 180mm to 220mm; the widths of the upper yoke 13 and the lower yoke 14 range from 350mm to 400mm.

[0008] Beneficial effects: This technical solution adopts a three-phase five-limb iron core structure. While ensuring the creepage distance between the incoming and outgoing ends of the high-voltage coil, the upper spacing D and lower spacing d of the high-voltage coil are sufficient to meet the insulation level requirements. The width of the upper and lower yokes of the three-phase five-limb iron core is relatively narrow, approximately 50% to 55% of the width of the existing three-phase three-limb iron yokes, reducing the overall height of the transformer. While ensuring electrical performance, it meets the requirement that the overall height of the transformer be less than 4.6m for automobile transportation, thus resolving the contradiction between insulation performance requirements and dimensional height limitations in existing technologies.

[0009] In a preferred embodiment, high-voltage coil air passages are respectively provided axially between each layer of the high-voltage coil for ventilation and heat dissipation of the high-voltage coil; Low-voltage coil air channels are provided axially between each layer of the low-voltage coil to provide ventilation and heat dissipation for the low-voltage coil.

[0010] In a preferred embodiment, both the high-voltage coil and the low-voltage coil are prepared using an epoxy resin vacuum casting process.

[0011] Beneficial effects: The use of axial air channels and epoxy resin vacuum casting ensures that the dry-type transformer does not contain flammable transformer oil or greenhouse gas SF6, has strong short-circuit resistance, and has the advantages of safety, flame retardancy, and environmental protection.

[0012] In a preferred embodiment, the multi-segment layered coil of the high-voltage coil is formed by winding multiple wires together; and / or, The layered coils of the low-voltage coil are each made up of multiple transposed wires wound together.

[0013] In a preferred embodiment, the 110kV three-phase dry-type transformer further includes an on-load tap changer. The upper half of the high-voltage coil has an off-load tap changer, and the lower half of the high-voltage coil has an on-load tap changer. The on-load tap changer switch is connected to the on-load tap changer.

[0014] Beneficial effects: On-load tap changers can achieve on-load tap regulation within a nine-tap range; off-load tap changers can adjust the rated high voltage of the transformer within the off-load regulation range.

[0015] In a preferred embodiment, an inlet insulator is provided at the inlet end of the high-voltage coil, and an inlet end equalizing cover is provided on the inlet end insulator.

[0016] Beneficial effects: The insulator at the input end can increase the air gap between the conductor at the input end and the ground potential structure, meeting the standard requirements for the minimum air gap; the equalizing cover at the input end can improve the electric field distribution at the input end and enhance the impulse voltage withstand capability of the high-voltage coil input end.

[0017] In a preferred embodiment, a high-voltage upper insulating support block is provided at the upper end of the high-voltage coil, and a low-voltage upper insulating support block is provided at the upper end of the low-voltage coil. The high-voltage upper insulating support block and the low-voltage upper insulating support block are spaced apart and are air-isolated. The lower ends of the low-voltage coil and the high-voltage coil are provided with an integrated coil lower insulation support block.

[0018] Beneficial effects: The insulating support block mainly serves to fix the coil; the air-isolated high-voltage upper insulating support block and the low-voltage upper insulating support block can increase the surface creepage distance of the solid insulation between the upper high-voltage coil and the low-voltage coil, improve the pollution resistance of the high-voltage coil inlet insulation, and reduce partial discharge.

[0019] In a preferred embodiment, at least one first insulating sleeve is provided between the low-voltage coil and the core column.

[0020] In a preferred embodiment, a plurality of second insulating cylinders are provided between the high-voltage coil and the low-voltage coil, and the plurality of insulating cylinders are usually evenly arranged between the high-voltage coil and the low-voltage coil.

[0021] In a preferred embodiment, a plurality of insulating partitions are provided between two adjacent high-voltage coils, and / or between a high-voltage coil and an adjacent side post.

[0022] Beneficial effects: The first insulating cylinder, the second insulating cylinder, and the insulating partition can effectively improve the insulation level between the coil and the isolated object. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A schematic diagram of the structure of a 110kV three-phase dry-type transformer provided in an embodiment of this application; Figure 2 This is a schematic diagram of a partial cross-sectional structure of a high-voltage coil provided in an embodiment of this application; Figure 3 A schematic diagram of the connection between the high-voltage coil and the on-load tap changer provided in the embodiments of this application; Figure 4 This is a schematic diagram of the cross-sectional structure of the low-voltage coil provided in an embodiment of this application; Figure 5 This is a schematic diagram of a partial cross-sectional structure of a low-voltage coil provided in an embodiment of this application; Figure 6 This is a schematic diagram of the insulation structure provided in an embodiment of this application; Numbering on the map: 1-Three-phase five-column iron core; 11-Core column; 12-Side column; 13-Upper yoke; 14-Lower yoke; 2-High voltage coil; 21-High voltage coil inlet end; 22-High voltage coil outlet end; 211-Inlet end insulator; 212-Inlet end equalizing cover; 221-Outlet end connecting rod; 23-High voltage coil air passage; 3-Low-pressure coil; 31-Upper outlet of low-pressure coil; 32-Lower outlet of low-pressure coil; 33-Low-pressure coil air passage; 34-Transposition wire; 4-On-load tap changer; 51-High voltage upper insulation support block; 52-Low voltage upper insulation support block; 53-Coil lower insulation support block; 61-First insulating cylinder; 62-Second insulating cylinder; 63-Insulating partition. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. The components of the embodiments of this application described and labeled in the accompanying drawings can generally be arranged and designed in various different configurations.

[0026] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0030] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] like Figures 1-4 As shown, this application embodiment provides a 110kV three-phase dry-type transformer, including: a three-phase five-limb core 1. Specifically, the three-phase five-limb core 1 includes three core columns 11 arranged side by side in the middle, and two side columns 12 arranged on both sides of the core columns 11; an upper yoke 13 is arranged above the core columns 11 and the side columns 12, and a lower yoke 14 is arranged below; each core column 11 is fitted with a low-voltage coil 3 and a high-voltage coil 2 from the inside out, and the three low-voltage coils 3 and the high-voltage coils 2 respectively form a three-phase low-voltage winding and a three-phase high-voltage winding; no coils are fitted on the two side columns 12. The high-voltage coil 2 is a multi-segment layered coil structure with an upper inlet and a lower outlet, featuring an axial air passage and manufactured using an epoxy resin vacuum casting process. Each of the three high-voltage coils 2 has a high-voltage coil inlet 21 at the upper part, with phase numbers A, B, and C respectively; and a high-voltage coil outlet 22 at the lower part, with phase numbers X, Y, and Z respectively. The three high-voltage coil outlets 22 are connected by outlet connecting rods 22. The low-voltage coil 3 is a layered coil structure with end-entry and end-exit wires. It also has an axial air passage and is manufactured using an epoxy resin vacuum casting process. The three low-voltage coils 3 are respectively provided with an upper low-voltage coil inlet 31 at the top and a lower low-voltage coil outlet 32 ​​at the bottom. The air distance between the upper end of the high-voltage coil 2 and the upper yoke 13 is the upper spacing D, and the air distance between the lower end of the high-voltage coil 2 and the lower yoke 14 is the lower spacing d, and D > d, thus forming a graded insulation structure. In this embodiment, the upper spacing D ranges from 400mm to 500mm, and the lower spacing d ranges from 180mm to 220mm.

[0033] In this embodiment, while ensuring the creepage distance between the inlet and outlet ends of the high-voltage coil 2, the upper spacing D at the top end and the lower spacing d at the bottom end of the high-voltage coil 2 are sufficient to meet the insulation level requirements.

[0034] The upper yoke 13 and lower yoke 14 are approximately 380 mm wide, while the existing three-phase three-column yoke is approximately 720 mm wide. Therefore, the width of the upper and lower yokes in this embodiment is approximately 53% of that in the prior art. The narrower upper yoke 13 and lower yoke 14, while ensuring electrical performance, meet the requirement that the overall height of the transformer is less than 4.6 m for automobile transportation, thus solving the problem of the contradiction between insulation performance requirements and size height limitations in the prior art.

[0035] The high-voltage coil 2 and the low-voltage coil 3 adopt axial air channels and epoxy resin vacuum casting, so that the dry-type transformer does not contain flammable transformer oil or greenhouse gas SF6 gas, has strong short-circuit resistance, and has the advantages of safety, flame retardancy and environmental protection.

[0036] In a preferred embodiment of this example, such as Figure 2 As shown, the high-voltage coil 2 adopts a multi-segment four-layer coil structure with six conductors wound in parallel. A high-voltage coil air passage 23 for ventilation and heat dissipation is provided between each layer of coil along the axial direction. Furthermore, an inlet insulator 211 is provided at the inlet end 21 of the high-voltage coil, and an inlet end equalizing cover 212 is provided on the inlet end insulator 211. The insulator 211 at the input end can increase the air gap between the conductor at the input end and the ground potential structure to meet the standard requirements for the minimum air gap; the equalizing cover 212 at the input end can improve the electric field distribution at the input end and improve the impulse voltage withstand capability of the input end 21 of the high voltage coil.

[0037] In a preferred embodiment of this example, such as Figure 3 As shown, each phase of the high-voltage coil 2 has an off-load tap changer in the upper half and an on-load tap changer in the lower half. Each phase of the high-voltage coil 2 is connected to its corresponding on-load tap changer via an on-load tap changer 4. Terminals 0 to 9 of the on-load tap changer are connected to terminals 0 to 9 of the on-load tap changer 4. On-load tap changer 4 allows for nine-tap range on-load tap adjustment; off-load tap changer allows for adjustment of the transformer's rated high-voltage operating range within the off-load adjustment range. In a preferred embodiment of this example, such as Figure 4 As shown, the low-voltage coil 3 is a four-layer coil, each layer of the coil is made up of four transposed wires 34 wound together, and there are low-voltage coil air channels 33 arranged along the axial direction between each layer of the coil for ventilation and heat dissipation; and a first insulating cylinder 61 is also provided between the low-voltage coil 3 and its core column 11. like Figure 5 As shown, each transposition wire 34 of the low-voltage coil 3 is composed of 9 strands of wire. In an optional implementation of this embodiment, such as Figure 6 As shown, high-voltage upper insulating support blocks 51 are respectively installed on the upper ends of the three high-voltage coils 2; low-voltage upper insulating support blocks 52 are respectively installed on the upper ends of the three low-voltage coils 3. A gap is left between the corresponding high-voltage upper insulating support blocks 51 and low-voltage upper insulating support blocks 52 to achieve air isolation. An integrated coil lower insulating support block 53 is installed at the lower end of the corresponding high-voltage coil 2 and low-voltage coil 3. The high-voltage upper insulating support block 51, the low-voltage upper insulating support block 52, and the coil lower insulating support block 53 mainly serve to fix the high-voltage coil 2 and the low-voltage coil 3. The air isolation structure of each corresponding high-voltage upper supporting insulating block 51 and low-voltage upper supporting insulating block 52 can increase the surface creepage distance of the solid insulation between the upper high-voltage coil 2 and the low-voltage coil 3, improve the insulation and pollution resistance of the high-voltage coil inlet terminal 21, and reduce partial discharge. A first insulating cylinder 61 is provided between the low-voltage coil 3 and the core column 11; three second insulating cylinders 62 are provided between the high-voltage coil 2 and the low-voltage coil 3, and the three insulating cylinders 62 are evenly spaced between the high-voltage coil 2 and the low-voltage coil 3; three insulating partitions 63 are evenly spaced between two adjacent high-voltage coils 2 and between the high-voltage coil 2 and the adjacent side column 12. The first insulating cylinder 61, the second insulating cylinder 62, and the insulating partition 63 can improve the insulation level between the coil and the isolated object, such as improving the insulation level between the low-voltage coil 3 and the core column 11, improving the insulation level between the high-voltage coil 2 and the low-voltage coil 3, and improving the insulation level between the high-voltage coil 2 and the side column 12.

[0038] In other embodiments, the number of the first insulating cylinder 61, the second insulating cylinder 62, and the insulating partition 63 can also be adjusted according to technical needs, as long as the insulation requirements are met.

[0039] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A 110kV three-phase dry-type transformer, characterized in that, Including three-phase five-column iron core; The three-phase five-column iron core includes three core columns arranged in parallel, and two side columns arranged on both sides of the three core columns; an upper yoke is provided above the core columns and the side columns, and a lower yoke is provided below them; Each core column is fitted with a low-voltage coil and a high-voltage coil from the inside out. The three sets of low-voltage coils and the three sets of high-voltage coils respectively form a three-phase low-voltage winding and a three-phase high-voltage winding. The high-voltage coil is a multi-segment layered coil with wires entering at the top and exiting at the bottom, and the low-voltage coil is a layered coil with wires entering and exiting at the ends. The upper spacing D between the upper end of the high-voltage coil and the upper yoke is greater than the lower spacing d between the lower end of the high-voltage coil and the lower yoke, thus forming a graded insulation structure.

2. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, High-voltage coil air channels are respectively provided along the axial direction between each layer of the high-voltage coil for ventilation and heat dissipation of the high-voltage coil. Low-voltage coil air channels are provided axially between each layer of the low-voltage coil to provide ventilation and heat dissipation for the low-voltage coil.

3. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, Both the high-voltage coil and the low-voltage coil are manufactured using an epoxy resin vacuum casting process.

4. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, The multi-segment layered coil of the high-voltage coil is composed of multiple wires wound together; and / or, The layered coils of the low-voltage coil are each made up of multiple transposed wires wound together.

5. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, It also includes on-load tap changers; The upper half of the high-voltage coil has an off-load tap changer, and the lower half of the high-voltage coil has an on-load tap changer. The on-load tap changer switch is connected to the on-load tap changer.

6. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, An inlet insulator is provided at the inlet end of the high-voltage coil, and an inlet equalizing cover is provided on the inlet insulator.

7. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, A high-voltage upper insulating support block is provided at the upper end of the high-voltage coil, and a low-voltage upper insulating support block is provided at the upper end of the low-voltage coil. The high-voltage upper insulating support block and the low-voltage upper insulating support block are spaced apart and are air-isolated. The lower ends of the low-voltage coil and the high-voltage coil are provided with an integrated coil lower insulation support block.

8. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, At least one first insulating sleeve is provided between the low-voltage coil and the core column.

9. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, Multiple second insulating cylinders are provided between the high-voltage coil and the low-voltage coil, and the multiple insulating cylinders are evenly arranged between the high-voltage coil and the low-voltage coil.

10. The 110kV three-phase dry-type transformer according to claim 1, characterized in that, Multiple insulating partitions are provided between two adjacent high-voltage coils, and / or between a high-voltage coil and an adjacent side post.

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