Split winding uniform electric field structure and use method

Abstract

The invention discloses a split winding uniform electric field structure and a using method, and relates to the field of high-voltage transformer insulation design, the uniform electric field structure comprises a low-voltage U-shaped coil, a high-voltage coil and an electrostatic ring, the low-voltage U-shaped coil surrounds the outer side of an iron core in a split mode in the axial direction of the iron core, and the high-voltage coil is wound around the electrostatic ring. The high-voltage coil is arranged on the outer side of the low-voltage U-shaped coil, a hollow part is formed at the split part of the low-voltage U-shaped coil, and the electrostatic ring is arranged at the hollow part. The problem that the maximum field intensity and the average field intensity between the windings cannot be reduced while the insulation distance between the windings is reduced in the prior art can be solved.

Description

Technical Field

[0001] The invention relates to the field of high voltage transformer insulation design, and in particular to a split winding uniform electric field structure and a use method thereof. Background Art

[0002] In the design of power transformers and similar electrical equipment, when the splitting factor of the axially split transformer increases to 3.5 or higher, in order to ensure the stability and safety of the electrical performance, it is usually necessary to increase the spacing between the upper and lower low-voltage coils. This design adjustment is intended to address the problem of electrical stress concentration that may occur under high splitting factors. However, as the upper and lower spacing of the low-voltage coil increases, a large space gap will appear in the middle area of ​​the coil, which is called "leakage". This leakage phenomenon causes the electric field distribution in this area to become uneven, and local electric field disorder occurs. Especially when the high-voltage middle line is connected, that is, facing the highest voltage area at the head end of the high-voltage winding, it is found through simulation calculations that this area has become a weak point in the insulation system. This may not only reduce the insulation performance of the equipment, but also increase the risk of equipment failure.

[0003] To address this problem, the traditional method is to increase the distance between windings by directly increasing the insulation distance of the main air path. Although this method can directly and effectively reduce the field strength and ensure electrical safety, its high cost and restrictions on industrial design make it impractical in modern industrial production.

[0004] Therefore, how to effectively reduce the maximum field strength and average field strength between windings while reducing the insulation distance between windings without significantly increasing costs has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The object of the present invention is to provide a split winding uniform electric field structure and a method of use, so as to solve the problem that the prior art cannot reduce the maximum field strength and average field strength between windings while reducing the insulation distance between windings.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, a split winding uniform electric field structure includes: a low-voltage U-shaped coil, a high-voltage coil and an electrostatic ring, wherein the low-voltage U-shaped coil is split along the axial direction of the iron core and wrapped around the outside of the iron core, and the high-voltage coil is arranged on the outside of the low-voltage U-shaped coil. A leakage is generated at the split point of the low-voltage U-shaped coil, and the electrostatic ring is installed at the leakage point.

[0007] In some embodiments, the electrostatic ring is closely attached to the conducting wire of the low-voltage U-shaped coil along the slope direction formed by the tangent line of the low-voltage U-shaped coil and the axis line.

[0008] In some embodiments, a wire outlet bevel is provided on the electrostatic ring.

[0009] In some embodiments, the low-voltage U-shaped coil is divided into an upper half phase of the low-voltage U-shaped coil and a lower half phase of the low-voltage U-shaped coil, a leakage is formed between the upper half phase of the low-voltage U-shaped coil and the lower half phase of the low-voltage U-shaped coil, and the electrostatic rings are respectively installed at the outer transposition positions of the upper half phase of the low-voltage U-shaped coil and the lower half phase of the low-voltage U-shaped coil.

[0010] In some embodiments, the high-voltage coil is divided into two upper and lower coils connected in parallel, and the wire is fed into the middle of the high-voltage coil.

[0011] In some embodiments, a voltage regulating coil is further included, and the voltage regulating coil is arranged outside the high-voltage coil.

[0012] In some embodiments, the voltage regulating coil is a two-part coil connected in parallel, and the voltage regulating coil has radial output wires.

[0013] In some embodiments, the low voltage U-shaped coil is a spiral coil.

[0014] In a second aspect, a method for using a split winding uniform electric field structure is provided, based on a split winding uniform electric field structure according to any one of claims 1 to 8, comprising the following steps: The low-voltage U-shaped coil is split up and down along the axial direction of the iron core and wrapped around the outer side of the iron core to form an upper half phase of the low-voltage U-shaped coil and a lower half phase of the low-voltage U-shaped coil; An electrostatic ring is installed at the outer transposition position of the upper half phase of the low-voltage U-shaped coil, and an electrostatic ring is installed at the outer transposition position of the lower half phase of the low-voltage U-shaped coil to achieve a uniform electric field.

[0015] In some embodiments, the splitting coefficient of the low voltage U-shaped coil is ≥3.5.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a split winding uniform electric field structure. By installing an electrostatic ring at the split of the low-voltage U-shaped coil, the electric field distribution between the windings can be effectively improved, and the influence of the high-voltage coil head end and the high field strength concentration area on the middle of the upper and lower split low-voltage coil can be effectively improved, and the weak points caused by local field strength disorder to the low-voltage coil can be reduced. At the same time, the present invention installs an electrostatic ring at the hollow part to reduce the insulation distance between the windings, solving the problem that the existing technology cannot reduce the maximum field strength and average field strength between the windings while reducing the insulation distance between the windings.

[0017] Furthermore, the present invention arranges an inclined outlet for the conductor on the electrostatic ring to optimize the outlet mode of the coil, thereby improving the reliability and safety of the outlet while maintaining a uniform electric field.

[0018] Furthermore, the present invention installs the electrostatic rings at the outer transposition points of the upper half phase of the low-voltage U-shaped coil and the lower half phase of the low-voltage U-shaped coil, respectively, which can make the field strength at the transposition point of the low-voltage U-shaped coil uniform, increase the insulation strength at the transposition point, increase the insulation strength of the upper and lower wire corners at the transposition point, and reduce the insulation distance of the main air channel, effectively saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a U-shaped coil in a split winding uniform electric field structure provided by an embodiment of the present invention; Figure 2 A schematic diagram of an axially split transformer body to which a split winding uniform electric field structure provided by an embodiment of the present invention is applied; Figure 3 Schematic diagram of the unfolding of a U-shaped coil in an embodiment of the present invention, wherein (a) is a diagram of the inner side of the unfolded U-shaped coil, and (b) is a diagram of the outer side of the unfolded U-shaped coil; Figure 4 Schematic diagram of the middle transposition of the U-shaped coil in the embodiment of the present invention, wherein (a) is a schematic diagram of the upper half phase transposition of the U-shaped coil, and (b) is a schematic diagram of the lower half phase transposition of the U-shaped coil; Figure 5 Schematic diagram of an electrostatic ring used in an embodiment of the present invention, wherein (a) is a schematic diagram of the entire electrostatic ring, and (b) is a schematic diagram of the expansion of the electrostatic ring; Figure 6 The electric field analysis diagram provided by the embodiment of the present invention, wherein (a) is an electric field analysis diagram between the bottom of the low-voltage U-shaped coil and the first end of the high-voltage winding without the electrostatic ring installed, and (b) is an electric field analysis diagram between the bottom of the low-voltage U-shaped coil and the first end of the high-voltage winding after the electrostatic ring is installed; In the figure, 1. the upper phase of the low-voltage U-shaped coil; 2. the electrostatic ring of the upper phase; 3. the outer middle insulating ring; 4. the inner middle insulating ring; 5. the electrostatic ring of the lower phase; 6. the lower phase of the low-voltage U-shaped coil; 7. the upper phase of the high-voltage coil; 8. the insulating cylinder; 9. the support bar; 10. the lower phase of the high-voltage coil; 11. the inner wire of the upper phase of the low-voltage U-shaped coil; 12. the inner upper phase transposition of the low-voltage U-shaped coil; 13. the inner lower phase transposition of the low-voltage U-shaped coil; 14. the inner wire of the lower phase of the low-voltage U-shaped coil; 15. the outer wire of the upper phase of the low-voltage U-shaped coil; 16. the outer upper phase transposition of the low-voltage U-shaped coil; 17. the outer lower phase transposition of the low-voltage U-shaped coil; 18. the outer wire of the lower phase of the low-voltage U-shaped coil. DETAILED DESCRIPTION

[0020] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the specific embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0021] In the following description, a large number of details are given to provide a more thorough understanding of the present disclosure. However, it is obvious to those skilled in the art that the present disclosure can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present disclosure, some technical features known in the art are not described; that is, all features of actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0022] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present disclosure necessarily has the first element, component, region, layer or part.

[0023] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present disclosure. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0024] In the design of power transformers, the balance between the insulation distance between windings and the field strength has always been a technical problem. Traditional solutions often find it difficult to effectively reduce the field strength between windings while reducing the insulation distance between windings, thereby limiting the further improvement of transformer performance. In order to solve this problem, this embodiment proposes an innovative split winding uniform electric field structure, which realizes the uniformity of electric field distribution by introducing a new type of electrostatic ring design, and provides a reliable method for reducing the main airway distance. The split winding uniform electric field structure is mainly used in a split transformer, which is characterized in that the low-voltage coil adopts a U-shaped spiral coil structure composed of multiple wires, and realizes the uniform distribution of the electric field by axial splitting. At the transposition rising layer of the low-voltage U-shaped coil, this embodiment cleverly installs an electrostatic ring, which is close to the wire according to the slope of the spiral coil, and sets multiple wire outlet bevels to meet the outlet requirements of multiple wires. This design not only shields the sharp corners at the coil transposition, reduces the leakage distance, but also significantly enhances the insulation strength of the upper and lower exposed parts at the winding transposition. Experimental data show that after installing the electrostatic ring, the electric field distribution of the split low-voltage U-shaped coil is more uniform, the maximum field strength and the average field strength are significantly reduced, and the power line margin is also increased. This not only provides the possibility of reducing the main airway distance, but also effectively improves the operating stability and reliability of the transformer. The split winding uniform electric field structure and its electrostatic ring design provided in this scheme are an innovative transformer electric field optimization scheme. It not only solves the technical problem of balancing the insulation distance and field strength between windings in traditional transformer design, but also provides strong support for improving the performance of the transformer, reducing costs and extending the service life. The specific scheme is specifically introduced through the following embodiments.

[0025] Embodiment 1 In order to solve the problem that it is impossible to reduce the field strength between windings while reducing the insulation distance between windings, this embodiment provides a split winding uniform electric field structure, in which a new type of electrostatic ring is installed at the leakage point to shield the sharp corners and reduce the leakage distance. The difficulty of the split winding uniform electric field structure is that the low-voltage coil is a U-shaped spiral coil structure composed of multiple wires, such as Figure 3 and Figure 4 As shown in the figure, the position of the electrostatic ring in the middle is at the U-shaped bottom transposition layer of the low-voltage U-shaped coil. The existing electrostatic rings are all planar rings, which are used to shield the ends of the coils and change the distorted electric field at the ends. The electrostatic ring provided in this embodiment is close to the wire according to the slope of the spiral low-voltage U-shaped coil. At the same time, if there are several wires, several wire outlet bevels will be set on the electrostatic ring for wire outlet, such as Figure 5 shown.

[0026] The split winding uniform electric field structure includes a split low-voltage U-shaped coil, a high-voltage coil and an electrostatic ring, which is applied to a split transformer, and is implemented by low-voltage axial splitting. The split transformer has a rated capacity of 80 / 45-45 / 22.5MVA, a rated voltage of (525±8×1.25%) / 10.5-10.5 / 6.3kV, adopts axial splitting, and a splitting coefficient of ≥3.5. Figure 2 As shown, the structure of the split transformer is arranged in order: iron core, stabilizing coil, low-voltage coil, high-voltage coil and voltage regulating coil. The high-voltage coil adopts a parallel design of the middle incoming line, which is divided into the upper half phase 7 of the high-voltage coil and the lower half phase 10 of the high-voltage coil. The voltage regulating coil adopts a parallel upper and lower width-outlet design. The low-voltage coil adopts an axial split upper and lower outlet structure. The low-voltage coil is a spiral low-voltage U-shaped coil. An insulating cylinder 8 and a support bar 9 are set between the low-voltage coil and the high-voltage coil. Figure 1 As shown, the low-voltage U-shaped coil is split up and down along the axial direction of the iron core and surrounds the outer side of the iron core. The low-voltage U-shaped coil is divided into a low-voltage U-shaped coil upper phase 1 and a low-voltage U-shaped coil lower phase 6. An inner middle insulating ring 4 and an outer middle insulating ring 3 are arranged between the low-voltage U-shaped coil upper phase 1 and the low-voltage U-shaped coil lower phase. In order to meet the split coefficient ≥3.5, the gap between the low-voltage U-shaped coil upper phase 1 and the low-voltage U-shaped coil lower phase 6 is 170mm.

[0027] like Figure 3 and Figure 4 As shown, an inner middle insulating ring 4 is installed between the inner upper half phase transposition 12 of the low voltage U-shaped coil and the inner lower half phase transposition 13 of the low voltage U-shaped coil, and the inner side of the low voltage U-shaped coil has the inner conductor 11 of the upper half phase of the low voltage U-shaped coil and the inner conductor 14 of the lower half phase of the low voltage U-shaped coil. The upper half phase electrostatic ring 2 is arranged at the outer upper half phase transposition 16 of the low voltage U-shaped coil, and the lower half phase electrostatic ring 5 is arranged at the outer lower half phase transposition 17 of the low voltage U-shaped coil, and the outer side of the low voltage U-shaped coil has the outer conductor 15 of the upper half phase of the low voltage U-shaped coil and the outer conductor 18 of the lower half phase of the low voltage U-shaped coil.

[0028] like Figure 5 As shown in FIG. 1 , it is a schematic diagram of the structure of the electrostatic ring. The electrostatic ring has 24 gears in total, and is evenly marked along the circumference, where e, f, and d are the bevel positions of the wire outlets set on the electrostatic ring.

[0029] like Figure 6 As shown in the figure, after installing the electrostatic ring at the transposition of the upper half phase and the lower half phase of the split low-voltage U-shaped coil, the electric field distribution is more uniform, as shown in the following Tables 1 and 2, which significantly reduces the maximum field strength and the average field strength, and increases the power line margin, providing a reliable method for reducing the main air channel distance.

[0030] Table 1 Field strength analysis table of split low voltage U-shaped coil without electrostatic ring installed

[0031] Table 2 Field strength analysis of split low voltage U-shaped coil after installing electrostatic ring

[0032] A split winding uniform electric field structure provided in this embodiment can shield sharp corners and reduce the spacing between leakage holes, enhance the insulation strength of the upper and lower exposed parts of the winding transposition, increase the insulation strength of the sharp corners of the upper and lower wires at the transposition, and reduce the insulation distance of the main air channel, thereby effectively saving costs.

[0033] Embodiment 2 This embodiment provides a method for using a split winding uniform electric field structure based on the first embodiment, including the following steps: The low-voltage U-shaped coil is split up and down along the axial direction of the iron core and wrapped around the outer side of the iron core to form the upper half phase 1 of the low-voltage U-shaped coil and the lower half phase 6 of the low-voltage U-shaped coil; An electrostatic ring is installed at the outer transposition of the upper half phase 1 of the low voltage U-shaped coil, and an electrostatic ring is installed at the outer transposition of the lower half phase 6 of the low voltage U-shaped coil to further homogenize the electric field, especially in the leakage area caused by the splitting of the coil.

[0034] The splitting coefficient of the low-voltage U-shaped coil is ≥3.5, which ensures that the electric field distribution in the split coil is more uniform, reduces the possibility of local discharge, and improves the operating stability and life of the transformer.

[0035] The above-mentioned method of use is based on the following uniform electric field structure, which includes: a low-voltage U-shaped coil, a high-voltage coil, a voltage regulating coil and an electrostatic ring. The low-voltage U-shaped coil is split along the axial direction of the iron core and wrapped around the outside of the iron core. The high-voltage coil is arranged on the outside of the low-voltage U-shaped coil. A leakage is generated at the split point of the low-voltage U-shaped coil, and the electrostatic ring is installed at the leakage point.

[0036] The electrostatic ring is closely attached to the wire of the low-voltage U-shaped coil along the slope direction formed by the tangent line of the low-voltage U-shaped coil and the axis line, and the electrostatic ring is provided with a wire outlet bevel to ensure that the electric field can smoothly transition under the guidance of the electrostatic ring and reduce electric field distortion. The wire outlet bevel provided on the electrostatic ring facilitates smooth connection with the coil wire and reduces the electric field concentration point caused by improper connection.

[0037] The low-voltage U-shaped coil is divided into a low-voltage U-shaped coil upper phase 1 and a low-voltage U-shaped coil lower phase 6. A leakage is formed between the low-voltage U-shaped coil upper phase 1 and the low-voltage U-shaped coil lower phase 6. The electrostatic rings are respectively installed at the outer transposition positions of the low-voltage U-shaped coil upper phase 1 and the low-voltage U-shaped coil lower phase 6.

[0038] The high-voltage coil is divided into two coils connected in parallel, and the wire is introduced into the middle of the high-voltage coil, which is not only conducive to uniform current distribution, but also convenient for maintenance and overhaul.

[0039] The voltage regulating coil is arranged outside the high voltage coil. The voltage regulating line is two coils connected in parallel, and the voltage regulating coil is radially connected. This makes the structure of the entire transformer compact, reduces the floor space, and improves the flexibility and accuracy of voltage regulation.

[0040] The low voltage U-shaped coil is a spiral coil, which can more effectively utilize space, increase the filling factor of the coil, and thus improve the power density of the transformer. In addition, the spiral structure also helps to improve the heat dissipation conditions, reduce the coil temperature, and improve the overload capacity and long-term operation reliability of the transformer.

[0041] The method for using the uniform electric field structure provided in this embodiment has the following advantages: (1) Use spiral split low-voltage U-shaped coil: The low-voltage U-shaped coil is split into upper half phase and lower half phase along the axial direction of the core. This design helps to optimize the electric field distribution, especially in the leakage area caused by the coil splitting. The splitting coefficient is ≥3.5, ensuring that the electric field distribution in the split coil is more uniform, effectively reducing partial discharge, and improving the operating stability and service life of the transformer.

[0042] (2) Install a new type of electrostatic ring: Install electrostatic rings at the outer transposition points of the upper and lower phases of the low-voltage U-shaped coil to further homogenize the electric field, especially in the leakage area caused by the split coil. The electrostatic ring is close to the coil conductor along the slope formed by the tangent and axis of the low-voltage U-shaped coil, and an inclined outlet for the conductor is set to ensure that the electric field can transition smoothly under the guidance of the electrostatic ring and reduce electric field distortion.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A split winding uniform electric field structure, characterized in that: include: A low-voltage U-shaped coil, a high-voltage coil and an electrostatic ring, wherein the low-voltage U-shaped coil is split along the axial direction of the iron core and wrapped around the outside of the iron core, and the high-voltage coil is arranged on the outside of the low-voltage U-shaped coil. A leak is generated at the split of the low-voltage U-shaped coil, and the electrostatic ring is installed at the leak.

2. A split winding uniform electric field structure according to claim 1, characterized in that: The electrostatic ring is closely attached to the conducting wire of the low-voltage U-shaped coil along the slope direction formed by the tangent line of the low-voltage U-shaped coil and the axis line.

3. A split winding uniform electric field structure according to claim 2, characterized in that: The electrostatic ring is provided with an inclined outlet for the conductor.

4. The split winding uniform electric field structure according to claim 1, characterized in that: The low-voltage U-shaped coil is divided into a low-voltage U-shaped coil upper phase (1) and a low-voltage U-shaped coil lower phase (6), a leakage is formed between the low-voltage U-shaped coil upper phase (1) and the low-voltage U-shaped coil lower phase (6), and the electrostatic rings are respectively installed at the outer transposition positions of the low-voltage U-shaped coil upper phase (1) and the low-voltage U-shaped coil lower phase (6).

5. The split winding uniform electric field structure according to claim 1, characterized in that: The high-voltage coil is divided into two coil parts connected in parallel, and the wire is fed into the middle of the high-voltage coil.

6. The split winding uniform electric field structure according to claim 1, characterized in that: It also includes a voltage regulating coil, which is arranged outside the high-voltage coil.

7. The split winding uniform electric field structure according to claim 6, characterized in that: The voltage regulating coil is composed of two coil parts connected in parallel, and the voltage regulating coil has radially extending wires.

8. The split winding uniform electric field structure according to claim 1, characterized in that: The low-voltage U-shaped coil is a spiral coil.

9. A method for using a split winding uniform electric field structure, characterized in that: A split winding uniform electric field structure according to any one of claims 1 to 8 comprises the following steps: The low-voltage U-shaped coil is split up and down along the axis of the iron core and wrapped around the outer side of the iron core to form an upper half phase (1) of the low-voltage U-shaped coil and a lower half phase (6) of the low-voltage U-shaped coil; An electrostatic ring is installed at the outer transposition position of the upper half phase (1) of the low-voltage U-shaped coil, and an electrostatic ring is installed at the outer transposition position of the lower half phase (6) of the low-voltage U-shaped coil to achieve a uniform electric field.

10. The method for using the split winding uniform electric field structure according to claim 9, characterized in that: The splitting coefficient of the low-voltage U-shaped coil is ≥3.5.

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