EP4687161A1

EP4687161A1 - Coil arrangement, transformer and method

Info

Publication number: EP4687161A1
Application number: EP24199645.3A
Authority: EP
Inventors: Yongjin Liu; Qingjun SUN; Tianbing ZHENG
Original assignee: Hitachi Energy Ltd
Current assignee: Hitachi Energy Ltd
Priority date: 2024-07-31
Filing date: 2024-09-11
Publication date: 2026-02-04

Abstract

The invention relates to a coil arrangement (10) for an electrical transformer (1) and comprising
a coil (20) made from cast resin and with an axial end face (30) that comprises an engagement member (32), and
a coil block (50) configured for supporting the coil (20), arranged in contact to the axial end face (30) and engaging with the engagement member (32).

Description

Technical Field

The invention relates to a coil arrangement for an electrical transformer, which coil arrangement comprises a coil and a coil block configured for supporting the coil. The invention furthermore relates to an electrical transformer with a coil arrangement and to a method.

Background Art

In electrical transformers, due to relatively large volume and weight, a coil of a coil arrangement may vibrate during operation. Additionally, dimensions of the coil may vary over time or depending on conditions in use. In this respect, a coil block may provide mechanical stability and especially resistance against vibrations and/or change in dimensions. It is a problem to provide sufficient lifetime of the coil arrangement while maintaining mechanical stability.
There is a desire to develop a coil arrangement that simplifies the assembly process while ensuring robust mechanical stability and optimal stress distribution. Such an arrangement would ideally include fewer components, be easier to manufacture, and offer enhanced stability and performance compared to existing designs.

Summary of invention

It is an object of the invention to provide solutions with respect to coil arrangements for electrical transformers that provide increased lifetime, lower cost to produce and an easier assembly. Particularly it is an object to avoid or reduce disadvantages of known solutions.
The object of the invention is solved by the features of the independent claims. Preferred implementations are detailed in the dependent claims, the description and the figures.
The object is particularly solved by a coil arrangement for an electrical transformer. The coil arrangement comprises a coil made from cast resin (also referred to as 'resin cast coil') and with an axial end face that comprises an engagement member. The coil arrangement comprises a coil block configured for supporting the coil, arranged in contact to the axial end face and engaging with the engagement member.
In other words, particularly, the present invention suggests a coil system for a dry-type transformer that includes a coil with an axial end surface featuring an engagement geometry. Additionally, a block member is provided that supports the coil, with the block member being in contact with the axial end surface and engaging in a circumferential and/or radial direction with the engagement geometry. This configuration enhances the stability and support of the coil within the transformer.
By means of the invention and by means of aspects described in the present application, it is advantageously realized that the coil can be produced at lower cost while the engagement between coil and coil block enhances mechanical stability.
The invention provides by means of the engagement member, relative to known solutions, an additional fixation of the coil at its bottom. The coil arrangement may exhibit a better performance in an environment with vibrations. The engagement member may be produced easily and at low cost, e.g. when casting the coil.
The coil, particularly a coil member thereof, comprises an axial end face. The axial end face typically has a flat shape and/or a substantially ring shape. The axial end face typically faces away from the body of the respective coil member, particularly along an axial direction of the coil. It may be understood that the axial end face can be placed onto another axial end face or onto coil blocks.
The engagement member may be configured for engagement, e.g. in order to provide a form fit or positive fit. For example, the engagement member may engage when placed onto or atop a coil member. The engagement member may have a non-flat and/or three-dimensionally extending shape for engagement. The engagement member may have or may be an extrusion. The engagement member may be configured to be in contact to the coil block and thereby engaging therewith. The engagement may include that the engagement member at least sectionally surrounds the coil block, e.g. a support section thereof. For example, the coil block may project at least sectionally into the engagement member or project into a space between parts thereof. The engagement may provide a form fit that is effective in a radial and/or circumferential direction with respect to the coil.
The coil block may be in direct or indirect contact to the axial end face, e.g. in direct physical contact or with a spacer, mat or flexible member in between providing a distance but a mechanical linkage for transmission of forces. The coil block may be in contact in terms of area with the engagement member for load distribution.
Electrical transformers are known in the art. Transformers typically include a coil arrangement with at least one coil which coil can be supported by a coil block of the coil arrangement. Typical coil blocks can provide mechanical support of the coil and preferably electrical insulation. A longitudinal axis of the coil is typically arranged vertically. The coil can be supported by the coil block provided between an upper end of the coil and a support base, and between an upper end of the coil and another one of the support base. The coil blocks can provide the coil with sufficient stiffness to prevent vertical motion of the coil relative to the support bases. The transformer may be provided as a one, two or three phase transformer. Therefor, the transformer may comprise one, two or three coils or coil arrangements. The coil arrangement, particularly the transformer, may be configured for medium voltages and/or high voltages. The coil arrangement, particularly the transformer, may be configured to be used in electrical power distribution applications, for example in a distribution substation. The coil may have an outer diameter that is least 0.5 m and/or up to 1.5 m. The outer diameter particularly is at least 0.75 m and/or up to 1.25 m, particularly is 1.1 m ± 0.1 m. A length of the coil along an axial direction may be at least 0.5 m and/or up to 2 m. The coil may have a primary coil section and a secondary coil section inside the primary coil section. A wall, for example in the form of an insulating barrier, may be arranged between said two coil sections. In an axial direction, the coil may comprise two or more separate coil members stacked atop each other which can form the coil.
The term high voltage means preferably a voltage above 12 kV or 36 kV or 72 kV or 1100 kV. A high voltage preferably relates to nominal voltages in the range from above 12 kV, 36 kV or 72 kV to 550 kV or 1100 kV, like 145 kV, 245 kV or 420 kV, or even more. The term medium voltage means preferably a voltage above 1 kV or 12 kV or 36 kV. A medium voltage preferably relates to nominal voltages in the range from above 1 kV, 12 kV or 36 kV to 72 kV, like 5 kV, 10 kV, 25 kV or 70 kV.
The coil is made from or includes cast resin, particularly is configured as a resin cast coil. The coil typically includes metallic windings which may be cast in epoxy resin. The coil may comprise the cast resin as a component of a composite material, e.g. the composite material including the cast resin and a fiber material embedded in the cast resin. The fiber material may be wound, e.g. arranged substantially in parallel to and/or substantially along the metallic windings.
The coil arrangement may have a support base. The support base is typically configured for supporting the coil. The support base may support the coil from at least one side. Supporting the coil may be understood in the sense of providing a foundation and/or a fixation. The support base may comprise a support beam. The support base may extend substantially obliquely or perpendicularly to an axial direction of the coil. The support base may support more than one coil, e.g. two or three coils which may be comprised by the coil arrangement.
The coil block can be arranged between the support base and the coil. The coil block may provide at least an indirect connection between the support base and the coil. The coil block may be in indirect or direct contact to the support base and/or the coil. The coil block may provide an electrical insulation for the coil relative to the ground. The coil block may comprise a substantially monolithic structure and/or a block shape. The block shape may comprise at least substantially a rigid and/or inflexible structure particularly configured for bearing loads along at least one direction. The coil block may have two support surfaces facing away from one another.
It may be provided that two or more, particularly three or four, of the engagement members and two or more, particularly three or four, of the coil blocks are provided and distributed substantially equidistantly along the axial end face in a circumferential direction of the coil. Each coil block may be assigned to one of the engagement members. This may ensure even distribution of support around the coil, enhancing its stability and reducing stress points.
The engagement member, particularly each engagement member, may comprise a pair of protrusions protruding axially from the axial end face. The protrusions of the pair of protrusions may be arranged at a distance to each other along the axial end face and/or in a circumferential direction with respect to the coil, e.g. for surrounding the coil block. The coil block may be arranged sectionally between the protrusions of said pair. The engagement member, particularly the protrusions, may have a trapezoidal and/or block shape. This can allow for a secure fit of the coil block within the engagement member, enhancing stability.
The pair of protrusions may comprise two lateral edges. The two lateral edges may face each other and/or may run substantially in parallel to a radial direction of the coil. The respective coil block, e.g. the coil block engaging with the pair of protrusions, may be arranged sectionally between the two lateral edges for provision of a form fit and/or positive fit. This form fit arrangement can ensure that the coil block is securely held in place relative to the coil, reducing or preventing movement during operation.
The coil block may comprise a support section. The support section may extend along an axial direction. The support section may have a substantially rectangular or square cross sectional shape. The support section may correspond to the thickness of the coil, particularly to the primary or secondary coil side thereof. The support section may have a substantially flat support face. The support surface is configured to be or is in contact with the axial end face. The support section may be arranged between the two protrusions of the pair of protrusions, especially between the two lateral edges. The support face may provide uniform contact and load distribution between the coil and the coil block.
The coil block may comprise or consist of a fiber reinforced polymer compound and/or an electrically insulating material. The fiber reinforced polymer compound may include glass fibers and/or carbon fibers and/or a thermoset resin, wherein the fibers may be embedded in the thermoset resin. The thermoset resin may include epoxy resin. The coil block may be a monolithically shaped cast part. The coil block may comprise ribs extending substantially perpendicularly to the extension of the coil. Thus, electrical and/or mechanical properties of the coil arrangement may be enhanced. The coil block may as well be produced at low cost with enhanced lifetime.
The engagement member may be formed monolithically and/or in one piece with a primary coil side of the coil. The engagement member may be a cast section of the coil. This monolithic formation may enhance the structural cohesion between the coil and the engagement member.
The coil may comprise a primary coil side and a secondary coil side, wherein the secondary coil side can be arranged radially inside the primary coil side. A wall may be provided between the primary and the secondary coil side. The engagement member may be formed in or with the primary coil side. This arrangement aims to optimize the spatial configuration and stability of the coil within the transformer. It may be sufficient that the engagement member is merely on the primary coil side and not on the secondary coil side.
The primary coil side and/or the secondary coil side may comprise or substantially consist of a polymer compound, e.g. which is made electrically insulating and particularly includes an epoxy resin or thermoset resin, carbon fibers, and/or glass fibers. The polymer compound is particularly fiber reinforced. The coil side(s) can be produced in a casting or molding process. The engagement member can be formed monolithically with the primary coil side, e.g. as a protrusions or protrusions thereof.
The coil blocks may each comprise a primary support section for the primary coil side and a secondary support section for the secondary coil side, particularly the support sections extending axially with respect to the coil and arranged at a radial distance to each other with respect to the coil. If provided, the wall may extend between the two support sections. This dual-section design aims to ensure that both the primary and secondary coil sides of the coil are adequately supported while electrical properties can be adapted as required.
The coil arrangement may comprise a flexible member. The flexible member may be arranged between the coil block and the coil. The flexible member may be in the form of a mat and/or may be substantially flat. The flexible member may be in contact on opposite sides to the coil block and to the coil, especially the contact extending across a surface area on both sides for load distribution. The flexible member may have a thickness along the axial direction of less than 30 mm, less than 20 mm, or less than 15 mm, particularly the thickness being 10 mm ± 5 mm. The flexible member may comprise or may be made from an electrically insulating material, particularly comprising rubber, a polymer compound and/or silicone. The flexible member may provide a dampening effect and a protection for the other components of the coil arrangement against failure from vibrations.
The coil arrangement may comprise another one of the support base for supporting the coil on a side opposite the support base, e.g. in the region of an upper lower side of the coil. The coil arrangement may comprise another one of the coil block arranged between the another one of the support base and the coil. The coil arrangement may comprise another one of the flexible member arranged between the another one of the coil block and the coil. The support base and the another one of the support base may be connected, e.g. via connecting rods extending along the coil. The mechanical stability of the coil arrangement may thus be enhanced.
The object may further be solved by a dry-type transformer including a/the coil arrangement, particularly wherein a/the coil of the coil arrangement may be configured for being arranged atop of a/the coil block of the coil arrangement. The dry-type transformer may comprise two or three of the coils, particularly arranged in a row.
The object is further solved by a method to produce one of the coil arrangement. The method comprises casting the coil, providing the coil block, and placing the coil on the coil block for the coil block to engage with the engagement member. This method aims to ensure a reliable and efficient process for assembling the coil arrangement.
The term 'or' may be replaced by 'and/or' throughout the present disclosure. As such, where 'or' is used, it is not necessarily meant that merely alternatives are named.

Brief description of drawings

These and other aspects of the invention will be apparent from and elucidated with reference to the implementations described hereinafter.
In the drawings:

Fig. 1 shows a part of a dry-type transformer in a perspective view;
Fig. 2 shows a part of another dry-type transformer in a perspective view; and
Fig. 3 shows a coil block of the transformer of Fig. 2 in a perspective view.

Description of implementations

The description contains procedural or methodical aspects upon describing structural features of the invention; the structural features can be understood well in that way. It is emphasized to the reader that such structural features can be lifted from the described context without hesitation or the question of an intermediate generalization to form aspects of the invention. It is also emphasized to the reader that any the structural features described in the following can be understood as individual aspects of the invention to distinguish from known solutions, despite being possibly lifted from the context.
Fig. 1 partially shows a dry-type transformer 1 including a coil arrangement 10, where a coil 20 is configured for being arranged atop a coil block 50. Presently, three coils 20 are arranged atop a number of coil blocks 50. Each coil 20 is arranged atop four coil blocks 50. The coil arrangement 10 includes three coils 20, one for each of three electrical phases the transformer 1 is configured to be electrically coupled to.
The three coils 20 are made from or include cast resin (e.g. also known as cast resin coils). Support bases 60 of the coil arrangement 10 are configured for supporting the coil 20 via coil blocks 50. The coil blocks 50 are arranged between the support base 60 and the coil 20 and thus are configured for supporting the coil 20. The support base 60 comprises steel beams.
The coils 20 include a radially inner secondary coil side 28 and an outer primary coil side 24 which are separated by a wall 26. The wall 26 is arranged radially between its primary coil side 24 and its secondary coil side. The wall 26 projects axially into the coil blocks 50, particularly into a support section 52 or gap thereof. The wall 26 particularly extends in an axial direction on both sides beyond the coil sides 24, 28.
The coil blocks 50 consist of an electrically insulating fiber reinforced polymer compound. The fiber reinforced polymer compound includes glass fibers or carbon fibers and a thermoset resin embedding the respective fibers.
The coil arrangement 10 includes one support base 60 at the top and one support base 60 at the bottom. Each coil 20 stands on and engages with four coil blocks 50, which coil blocks 50 stand on and are coupled, e.g. bolted, to the support base 60 at the bottom. At the top, each coil 20 is supported via four coil blocks 50 which are coupled to the support base 60, e.g. bolted thereto.
Thus, on both sides of each coil 20, four of the coil blocks 50 are provided and distributed substantially equidistantly along an axial end face 30 of the coil 20 and in a circumferential direction of the coil 20.
Each of the axial end faces 30 of the coils 20 that stand on and/or are supported by the coil blocks 50 comprise four engagement members 32 distributed substantially equidistantly along the axial end face 30 and in the circumferential direction of the coil 20. The engagement members 32 correspond to the coil blocks 50. Each of the coil blocks 50 at the bottom engages by means of a support section 52 thereof with one of the engagement members 32 and is in contact to the respective axial end face 30.
The engagement between each coil 20 and the respective four coil blocks 50 is effective in a circumferential direction of the coil 20. Considering that four coil blocks 50 engage in the circumferential direction along the axial end face 30, the engagement is effective in all radial directions similarly. The coil blocks 50 being fixed on the respective support base 60 provides a secure positioning of the coil 20.
In an axial direction, each coil 20 comprises two separate coil members stacked atop each other forming the respective coil 20. For example, each coil 20 has an outer diameter 22 of 1.1 m ± 0.1 m. Here, the three coils 20 are arranged in a row.
Between two adjacent coils 20 a partition wall 27 is arranged which can shield one coil 20 from the other coil 20. The partition wall 27 may be electrically insulating. The partition wall 27 may be fastened to one or to both support bases 60.
For electrical purposes, each coil block 50 has three ribs extending substantially perpendicularly to the extension of the coil 20 it supports.
The coil block 50 may be in contact to the primary coil side 24 of the coil 20 via an electrically insulating flexible member between the coil block 50 and the coil 20 which electrically insulating flexible member may have a thickness of 10 mm.
Fig. 2 shows a lower side or bottom of a coil arrangement 10 for a dry-type transformer 1. The coil arrangement 10 comprises a coil 20 that is made from cast resin and that has an axial end face 30. The axial end face 30 points downwards and/or towards the coil blocks 50. The axial end face 30 is substantially ring shaped and/or round.
The axial end face 30 comprises four engagement members 32 distributed substantially equidistantly along the axial end face 30 in a circumferential direction of the coil 20. Four coil blocks 50 of the coil arrangement 10 support the coil 20, are arranged in contact to the axial end face 30 and each engages with one of the four engagement members 32. The coil blocks 50 are supported by means of a support base 60 that includes steel beams. The coil 20 is arranged atop the coil blocks 50.
The coil 20 comprises a primary coil side 24 and a secondary coil side 28 that is arranged radially inside the primary coil side 24 with a wall 26 therebetween. Both coil sides 24, 28 exhibit one of the axial end face 30. The engagement members 32 are formed in the primary coil side 24, particularly with the axial end face 30 thereof. In detail, the engagement members 32 are formed monolithically with or in the primary coil side 24, e.g. as a protrusion or protrusions of the primary coil side 34.
It can be seen in Fig. 2 that each of the coil blocks 50 comprises a support section 52 for engaging with the engagement members. The support section includes a primary support section 54 for the primary coil side 24 and a secondary support section 58 for the secondary coil side 28. The support sections 54, 58 extend axially with respect to the coil 20. The support sections 54, 58 are arranged at a radial distance to each other with respect to the coil. Thus, a gap is formed between the support sections 54, 58 e.g. for receiving the wall 26 separating the primary and secondary coil sides 24, 28.
In the bottom of Fig. 2 a detail is shown that mainly relates to one of the four engagement members 32.
The engagement member 32 comprises a pair of protrusions 34 protruding axially from the axial end face 30. The protrusions 34 of said pair are arranged at a distance to each other along the axial end face 30 for surrounding a support section 52 of the coil block 50 from two sides.
A primary support section 54 of the support section 52 with a flat support face 56 is in contact to the axial end face 30 of the primary coil side 24 between the protrusions 34. A secondary support section 58 of the support section 52, also having a flat support face 56, is in contact to the axial end face 30 of the secondary coil side 28, however not engaging with an engagement member or with protrusions.
The protrusions 34 of said pair comprise two lateral edges 36 facing each other and running substantially in parallel to each other and/or to a radial direction of the coil 20. The primary support section 54 is arranged sectionally between the two lateral edges 36 for provision of a form fit.
The primary coil side 24 and the secondary coil side 28 comprise a fiber reinforced polymer compound which is made electrically insulating and particularly includes a thermoset resin and/or glass fibers. The coil sides 24, 28 have been produced in a casting or molding process. The engagement members 32 are formed monolithically with the primary coil side 24.
Producing the coil arrangement 10 of Fig. 2 may include casting the coil 20, providing the coil blocks 50, and placing the coil 20 on the coil blocks 50 for the coil block 50 to engage with the engagement members 32.
Fig. 3 shows one of the coil blocks 50 of Fig. 2. The coil block 50 includes a support section 52 with a primary support section 54 and a secondary support section 58. Each of the sections 54, 58 has a substantially flat support surface 56 on the top for supporting the coil 20. The primary support section 54 can engage with the engagement members 32 of the coil 20 (as shown in Fig. 2) by being placed between protrusions 34 of the engagement members 32.

Reference signs list

1: electrical transformer
10: coil arrangement
20: coil
22: outer diameter
24: primary coil side
26: wall
27: partition wall
28: secondary coil side
30: axial end face
32: engagement member
34: protrusion
36: edge
50: coil block
52: support section
54: primary support section
56: support face
58: secondary support section
60: support base

Claims

Coil arrangement (10) for an electrical transformer (1) and comprising
a coil (20) made from cast resin and with an axial end face (30) that comprises an engagement member (32), and

a coil block (50) configured for supporting the coil (20), arranged in contact to the axial end face (30) and engaging with the engagement member (32).
Coil arrangement (10) according to the preceding claim, wherein two or more, particularly three or four, of the engagement members (32) and two or more, particularly three or four, of the coil blocks (50) are provided and distributed substantially equidistantly along the axial end face (30) in a circumferential direction of the coil (20).
Coil arrangement (10) according to the preceding claim, wherein the engagement member (32) comprises a pair of protrusions (34) protruding axially from the axial end face (30), wherein the protrusions (34) of the pair of protrusions (34) may be arranged at a distance to each other along the axial end face (30) for surrounding the coil block (50).
Coil arrangement (10) according to the preceding claim, wherein the pair of protrusions (34) comprise two lateral edges (36), the two lateral edges (36) facing each other and/or running substantially in parallel to a radial direction of the coil (20), wherein the respective coil block (50) is arranged sectionally between the two lateral edges (36) for provision of a form fit.
Coil arrangement (10) according to any one of the preceding claims, wherein the coil block (50) comprises a support section (52) with a substantially flat support face (56) in contact to the axial end face (30).
Coil arrangement (10) according to the preceding claim, wherein the support section (52) is arranged between the two protrusions (34) of the pair of protrusions (34), especially between the two lateral edges (36).
Coil arrangement (10) according to any one of the preceding claims, wherein the coil block (50) comprises or consists of a fiber reinforced polymer compound and/or an electrically insulating material.
Coil arrangement (10) according to the preceding claim, the fiber reinforced polymer compound including a thermoset resin.
Coil arrangement (10) according to any one of the preceding claims, the fiber reinforced polymer compound including glass fibers and/or carbon fibers.
Coil arrangement (10) according to any one of the preceding claims, wherein the engagement member (32) is formed monolithically with a primary coil side (24) of the coil (20).
Coil arrangement (10) according to the preceding claim, wherein the coil (20) comprises the primary coil side (24) and a secondary coil side (28), wherein the secondary coil side (28) is arranged radially inside the primary coil side (24), and wherein the engagement members (32) are formed in the primary coil side (24).
Coil arrangement (10) according to the preceding claim, the coil blocks (50) each comprising a primary support section (54) for the primary coil side (24) and a secondary support section (58) for the secondary coil side (28), the support sections (54, 58) extending axially with respect to the coil (20) and arranged at a radial distance to each other with respect to the coil (20).
Coil arrangement (10) according to the preceding claim, wherein the coil (20) has an outer diameter (22), wherein the outer diameter (22) is least 0.5 m and/or up to 1.5 m, preferably is at least 0.75 m and/or up to 1.25 m, particularly is 1.1 m ± 0.1 m.
Dry-type transformer (1) including the coil arrangement (10) according to any one of the preceding claims, wherein the coil (20) is configured for being arranged atop the coil block (50).
Method to produce a coil arrangement (10) of any one of claims 1 to 13, comprising
casting the coil (20),

providing the coil block (50), and

placing the coil (20) on the coil block (50) for the coil block (50) to engage with the engagement member (32).