High-voltage coil winding structure for middle-high voltage distribution transformer

Abstract

According to the high-voltage coil winding structure for the middle-high voltage distribution transformer, a high-voltage coil comprises a wire inlet end and a wire outlet end, and the high-voltage coil is sequentially provided with a first section coil, a second section coil, a third section coil and a fourth section coil in a transverse sectional mode from top to bottom. Separation cushion blocks are transversely arranged between the second section of coil and the third section of coil in a separated mode, tapping areas are arranged on the outer sides of the second section of coil and the third section of coil, the maximum potential difference is arranged at the ends of the outer sides of the tapping areas, and the wire inlet end and the wire outlet end are arranged on the outer side of the high-voltage coil in an out-out and out-in mode. Due to the fact that the tapping area is located in the middle of the whole high-voltage coil, when rated tapping and minimum tapping are conducted, compared with a low-voltage coil, the ampere-turn unbalance degree is small, the anti-short-circuit capacity is greatly improved, the radial size is easier to control in the winding process, influences of the interlayer insulation shrinkage rate are avoided, the compactness is guaranteed, and the anti-short-circuit capacity is improved.

Description

Technical Field

[0001] This document belongs to the technical field of high-voltage coil winding of transformers, and specifically relates to a high-voltage coil winding structure for medium- and high-voltage distribution transformers. Background Art

[0002] For traditional distribution transformers, the high voltage is generally 35 kV and below, mostly 10 kV, and the low voltage is mainly 0.4 kV. The capacity is mostly 3150 kVA and below. The high-voltage coil of a traditional 10 kV distribution transformer generally adopts a one-section layer winding structure combined with a low-voltage foil winding structure. The high-voltage coil of a traditional 35 kV distribution transformer generally adopts a two-section layer winding structure.

[0003] For the traditional two-section structure, a structure of entering and exiting from the inside is generally adopted. The maximum voltage difference between sections is at the bottom. From the manufacturing process perspective, the insulation treatment at the bottom is more difficult. For traditional high-voltage layer coils, the tapping area is generally placed in the last one to three layers, rather randomly, without a fixed position.

[0004] As Figure 2 shown, for a transformer with a high voltage of 46 kV, the rated number of turns is relatively large, reaching 1096 turns, the turn voltage is 42 V, the total number of layers is 11 layers, and the number of turns per layer is about 108 turns. If a single section is adopted, the voltage between layers reaches 9 kV, and 28 sheets of interlayer insulation need to be placed (evaluated according to the withstand voltage of a single 0.08-point glue paper of 320 V), which completely does not meet the requirements of operability and economy. The conventional structure is divided into two sections, with 54 turns per layer, the voltage between layers is 4.5 kV, 14 sheets of interlayer insulation need to be placed, and the coil leads A and X adopt the inside-in and inside-out method. The maximum potential difference is at the bottom of the coil, at the section position, reaching 23 kV. Moreover, the creepage distance of paper insulation is evaluated at the bottom, and the allowable creepage electric field strength of cardboard is 1.35 kV / mm. While the external surface is evaluated for the pure oil distance, and the breakdown field strength of oil is 18 kV / mm. From the data, it is a better choice that the maximum field strength is on the external surface. The traditional structure requires a total of 77 sheets of interlayer insulation. This results in difficult control of the radial dimension during the winding process, loose winding, and affects the short-circuit resistance ability. Summary of the Utility Model

[0005] To solve the above problems, this paper proposes a high-voltage coil winding structure for medium- and high-voltage distribution transformers. The high-voltage coil includes an incoming line end and an outgoing line end. The high-voltage coil is horizontally segmented from top to bottom and successively provided with a first-stage coil, a second-stage coil, a third-stage coil, and a fourth-stage coil. The first-stage coil and the second-stage coil are wound together, and the third-stage coil and the fourth-stage coil are wound together. A separating spacer is horizontally arranged between the second-stage coil and the third-stage coil. Tap-changing zones are provided on the outer sides of the second-stage coil and the third-stage coil. The outer ends of the tap-changing zones have the maximum potential difference. The incoming line end and the outgoing line end are both arranged outside and entering outside the high-voltage coil. Since the tap-changing zone is located in the middle of the entire high-voltage coil, the ampere-turn imbalance is relatively small compared to the low-voltage coil during the rated tap and the minimum tap, greatly improving the short-circuit resistance. During the winding process, it is easier to control the radial dimension, not affected by the shrinkage rate of the interlayer insulation, ensuring the compactness and improving the short-circuit resistance.

[0006] Oil channels are arranged at intervals on the inner sides of the high-voltage coil. The oil channels are arranged between the inner sides of the first-stage coil, the second-stage coil, the third-stage coil, and the fourth-stage coil. The oil channels on the inner sides of the first-stage coil, the second-stage coil, the third-stage coil, and the fourth-stage coil are vertically aligned with each other. The maximum number of turns of each section of the first-stage coil, the second-stage coil, the third-stage coil, and the fourth-stage coil is 27 turns. For high-voltage distribution transformers, by dividing into four sections, compared with a one-section high-voltage coil, the interlayer voltage is reduced by 75%, and compared with a two-section high-voltage coil, it is reduced by 50%, fundamentally improving the operation reliability. In addition, after the interlayer voltage is reduced, the number of interlayer insulations also decreases, not only avoiding the situation of radial out-of-tolerance and coil looseness caused by the interlayer shrinkage rate, but also reducing the material cost and the artificial manufacturing cost.

[0007] The incoming line end is the A-line end head, and the outgoing line end is the B-line end head. The A-line end head is arranged at the upper outer side of the first-stage coil, and the B-line end head is arranged at the lower outer side of the fourth-stage coil. Through the four-section structure and the external incoming and outgoing structure, the maximum potential difference is on the outer surface of the coil, which is relatively convenient to handle and reduces the quality hidden dangers.

[0008] The material of the separating spacer is a paper support block. The shape of the separating spacer is annular. The separating spacer is independently arranged between the first-stage coil and the second-stage coil and the third-stage coil and the fourth-stage coil, fixing the tap-changing zone at the penultimate first and second layers, and located in the second and third sections, in the middle of the entire high-voltage coil. The ampere-turns are relatively balanced, and the short-circuit resistance is enhanced.

[0009] Beneficial effects:

[0010] Since the tap-changing section is located in the middle of the entire high-voltage coil, the ampere-turn imbalance is relatively small with respect to the low-voltage coil at the rated tap and the minimum tap, which greatly improves the short-circuit resistance. During the winding process, it is easier to control the radial dimension, and it is not affected by the shrinkage rate of the interlayer insulation, ensuring the compactness and improving the short-circuit resistance.

[0011] For high-voltage distribution transformers, by dividing it into four sections, compared with the high-voltage coil of one section, the interlayer voltage is reduced by 75%, and compared with the high-voltage coil of two sections, it is reduced by 50%, fundamentally improving the operation reliability. In addition, after the interlayer voltage is reduced, the number of interlayer insulations also decreases accordingly, which not only avoids the situation of coil radial dimension exceeding the tolerance and coil looseness caused by the interlayer shrinkage rate, but also reduces the material cost and the labor manufacturing cost.

[0012] Through the four-section structure and the use of the external-in and external-out structure, the maximum potential difference is on the outer surface of the coil, which is relatively convenient to handle and reduces the quality hidden danger.

[0013] Fix the tap-changing section at the penultimate and the second-to-last layers, and it is located in the second and third sections, in the middle of the entire high-voltage coil. The ampere-turns are relatively balanced, and the short-circuit resistance is enhanced. Description of the Drawings

[0014] Figure 1 is a winding schematic diagram of a high-voltage coil winding structure for a medium-voltage and high-voltage distribution transformer;

[0015] Figure 2 is a schematic diagram of the high-voltage coil winding structure of an existing traditional distribution transformer;

[0016] In the figure: 1. Coil bottom, 2. Oil duct, 3. Maximum potential difference, 4. Tap-changing section, 5. Separation spacer, 6. First-section coil, 7. Second-section coil, 8. Third-section coil, 9. Fourth-section coil, 10. Equipotential. Detailed Implementation Manner

[0017] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0018] Coil bottom 1, oil duct 2, maximum potential difference 3, tap-changing section 4, separation spacer 5, first-section coil 6, second-section coil 7, third-section coil 8, fourth-section coil 9, equipotential 10.

[0019] As Figure 1 shown;

[0020] A high-voltage coil winding structure for medium- and high-voltage distribution transformers. The high-voltage coil includes an incoming line end and an outgoing line end. The high-voltage coil is horizontally segmented from top to bottom and successively provided with a first-stage coil 6, a second-stage coil 7, a third-stage coil 8, and a fourth-stage coil 9. The first-stage coil 6 and the second-stage coil 7 are wound together. The third-stage coil 8 and the fourth-stage coil 9 are wound together. A separating spacer 5 is horizontally arranged between the second-stage coil 7 and the third-stage coil 8 in a separated manner. Tap-changing zones 4 are provided on the outer sides of the second-stage coil 7 and the third-stage coil 8. Maximum potential differences 3 are provided at the outer ends of the tap-changing zones 4. The incoming line end and the outgoing line end are both arranged on the outer side of the high-voltage coil in an outside-in and outside-out manner. Oil channels 2 are arranged at intervals on the inner side of the high-voltage coil. The oil channels 2 are arranged between the inner sides of the first-stage coil 6, the second-stage coil 7, the third-stage coil 8, and the fourth-stage coil 9. The oil channels 2 on the inner sides of the first-stage coil 6, the second-stage coil 7, the third-stage coil 8, and the fourth-stage coil 9 are vertically aligned with each other. The separating spacer 5 is made of a paper support block. The shape of the separating spacer 5 is annular. The separating spacer 5 is independently arranged between the first-stage coil 6 and the second-stage coil 7 and the third-stage coil 8 and the fourth-stage coil 9. The maximum number of turns of each stage of the first-stage coil 6, the second-stage coil 7, the third-stage coil 8, and the fourth-stage coil 9 is 27 turns. The incoming line end is an A-line end head. The outgoing line end is a B-line end head. The A-line end head is arranged at the upper outer side of the first-stage coil 6. The B-line end head is arranged at the lower outer side of the fourth-stage coil 9.

[0021] Implementation example;

[0022] Four segments are adopted, with a maximum of 27 turns per layer. The upper two segments are wound together, and the lower two segments are wound together. The upper and lower parts are independent coils. The support structure between the two independent coils is a cardboard plus spacer. The coil leads A and X of this structure adopt the outside-in and outside-out method. The maximum potential difference 3 is on the outer surface of the coil, only 11.5 kV, and the pure oil distance is examined. The insulation safety factor has been greatly improved compared with the traditional two segments. A total of 42 sheets of interlayer insulation need to be placed from the first layer to the outermost layer in the new structure, which is about 50% less than the traditional two-segment structure. During the winding process, it is easier to control the radial dimension, not affected by the shrinkage rate of the interlayer insulation, ensuring the tightness and improving the short-circuit resistance.

[0023] The transformer passes all routine tests and factory tests at one time. The high-voltage coil passes the assessment of the lightning impulse test voltage of 250 kV and the power frequency withstand voltage of 95 kV. It meets the established performance parameter requirements and standards.

[0024] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-voltage coil winding structure for a medium- and high-voltage distribution transformer, the high-voltage coil comprising an inlet terminal and an outlet terminal, characterized in that: The high-voltage coil is horizontally segmented from top to bottom and is provided with a first section coil, a second section coil, a third section coil and a fourth section coil in sequence. The first section coil and the second section coil are wound together, and the third section coil and the fourth section coil are wound together. A separation pad is horizontally separated between the second section coil and the third section coil. The outer sides of the second section coil and the third section coil are provided with a tapping area, and the outer ends of the tapping area are provided with a maximum potential difference. The input terminal and the output terminal are both arranged outside the high-voltage coil in an outward-outward manner.

2. A high voltage coil winding structure for a medium and high voltage distribution transformer according to claim 1, characterized in that: The inner side of the high-voltage coil is provided with oil passages at intervals, and the oil passages are arranged between the inner sides of the first section coil, the second section coil, the third section coil and the fourth section coil, and the oil passages inside the first section coil, the second section coil, the third section coil and the fourth section coil are vertically aligned with each other.

3. A high voltage coil winding structure for a medium and high voltage distribution transformer according to claim 1, characterized in that: The material of the separation pad is a paper support block, the shape of the separation pad is annular, and the separation pad is independently and separately arranged between the first and second sections of the coil and the third and fourth sections of the coil.

4. A high voltage coil winding structure for a medium and high voltage distribution transformer according to claim 1, characterized in that: The maximum number of turns of each of the first coil segment, the second coil segment, the third coil segment and the fourth coil segment is 27 turns.

5. The high voltage coil winding structure for medium and high voltage distribution transformer according to claim 1, characterized in that: The inlet terminal is the A-line terminal, the outlet terminal is the B-line terminal, the A-line terminal is arranged at the upper outer end of the first coil section, and the B-line terminal is arranged at the lower outer end of the fourth coil section.

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