Methods to improve the axial short-circuit withstand capability of vegetable oil transformers

Abstract

This invention relates to a method for improving the axial short-circuit withstand capability of a vegetable oil transformer. The method includes: arranging the number of turns of the high-voltage and low-voltage winding coils of the vegetable oil transformer in a symmetrical vertical structure, placing the partially turned coils at the upper and lower ends of the windings; and arranging the radial oil channels of the high-voltage and low-voltage windings in a symmetrical vertical structure, placing the larger oil channels at the upper and lower ends of the windings to ensure symmetrical oil channel arrangement. The above-mentioned solution provided in this application, by arranging the number of turns of the high-voltage and low-voltage winding coils in a symmetrical vertical structure, and simultaneously arranging the radial oil channels of the high-voltage and low-voltage windings in a symmetrical vertical structure, ensures symmetrical oil channel arrangement, thereby effectively reducing the ampere-turn imbalance rate of the windings, thereby reducing the radial leakage flux during winding short circuits, reducing the axial force on the coils, improving the axial stability of the windings, and improving the axial short-circuit withstand capability of the vegetable oil transformer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer manufacturing, in particular to a method for improving the axial short-circuit resistance of a vegetable oil transformer. BACKGROUND

[0002] With the enhancement of environmental protection and safety awareness in China, the application of vegetable oil transformer has been rapidly developed. As an important new type of environmentally friendly liquid insulation material, vegetable insulation oil has the advantages of high ignition point, excellent biodegradability, good electrical properties, wide raw material sources and renewability, etc. Therefore, the application of vegetable oil transformer is becoming more and more widespread.

[0003] Due to the large viscosity of vegetable oil, the oil flow resistance is large, and the height of the radial oil channel of the winding is usually increased to improve the heat dissipation performance. However, the increase of the height of the radial oil channel will cause the deviation of the ampere-turn imbalance rate of the transformer winding to become larger, resulting in the increase of the axial short-circuit force of the winding, which reduces the axial stability performance of the winding and affects the axial short-circuit resistance of the transformer, which is not conducive to the safe and stable operation of the transformer. SUMMARY

[0004] Therefore, it is necessary to provide a method for improving the axial short-circuit resistance of a vegetable oil transformer to solve the problem that the increase of the height of the radial oil channel will cause the deviation of the ampere-turn imbalance rate of the transformer winding to become larger.

[0005] The present application provides a method for improving the axial short-circuit resistance of a vegetable oil transformer, which comprises:

[0006] The turns of the high-voltage winding and the low-voltage winding of the vegetable oil transformer are arranged in an upper-lower symmetrical structure, and the incomplete-turn winding is placed at the upper and lower ends of the winding.

[0007] The radial oil channels of the high-voltage winding and the low-voltage winding of the vegetable oil transformer are arranged in an upper-lower symmetrical structure, and the large oil channel is placed at the upper and lower ends of the winding to ensure the symmetry of the oil channel arrangement.

[0008] The above-mentioned method for improving the axial short-circuit resistance of a vegetable oil transformer can effectively reduce the ampere-turn imbalance rate of the winding by arranging the turns of the high-voltage winding and the low-voltage winding in an upper-lower symmetrical structure, and arranging the radial oil channels of the high-voltage winding and the low-voltage winding in an upper-lower symmetrical structure, placing the large oil channel at the upper and lower ends of the winding to ensure the symmetry of the oil channel arrangement, thereby reducing the radial magnetic leakage when the winding is short-circuited, reducing the axial stress of the winding, improving the axial stability performance of the winding, and improving the axial short-circuit resistance of the vegetable oil transformer.

[0009] In one of the embodiments, after ensuring the symmetry of the oil channel arrangement, the method further comprises: adjusting the radial oil channel of the vegetable oil transformer winding, aligning the center heights of the high-voltage winding and the low-voltage winding.

[0010] In one of the embodiments, before arranging the turns of the high-voltage winding and the low-voltage winding of the vegetable oil transformer in an up-down symmetric structure, the method further comprises: dividing the winding turns into full-turn turns and incomplete-turn turns.

[0011] In one of the embodiments, the placing of the incomplete-turn turns at the upper and lower ends of the winding comprises: placing an incomplete-turn turn A at the upper end of the winding and placing an incomplete-turn turn B at the lower end of the winding, the number of turns and the length of the incomplete-turn turn A corresponding to the number of turns and the length of the incomplete-turn turn B.

[0012] In one of the embodiments, after ensuring the symmetry of the oil channel arrangement, the method further comprises: compressing each turn.

[0013] In one of the embodiments, the cross-sectional area of the conductors in the high-voltage winding and the low-voltage winding is constant.

[0014] In one of the embodiments, a shielding layer is arranged between the high-voltage winding and the low-voltage winding.

[0015] In one of the embodiments, the shielding layer comprises double-layer oil channel paper.

[0016] In one of the embodiments, the high-voltage winding has a middle outgoing wire.

[0017] In one of the embodiments, the number of turns and the length of the high-voltage winding are the same, the number of turns and the length of the low-voltage winding are the same, and the winding directions of the high-voltage winding and the low-voltage winding are the same. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A flowchart of a method for improving the axial short-circuit resistance of a vegetable oil transformer according to an embodiment of the present application is provided.

[0019] Figure 2 A structural diagram of a method for improving the axial short-circuit resistance of a vegetable oil transformer according to an embodiment of the present application is provided. DETAILED DESCRIPTION

[0020] In order to make the above objectives, features and advantages of the present application more clear and comprehensible, the specific embodiments of the present application will be described below in detail with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in many different ways from what is described herein, and should not be construed as being limited to the embodiments set forth herein, but should be understood to include all possible embodiments.

[0021] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are merely for the purpose of facilitating the description of the present application and simplifying the description, and therefore should not be construed as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application.

[0022] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implying a specified number of technical features indicated. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0023] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or can be integrated; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0024] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0025] It is to be understood that when an element as a preamble is referred to as being "on" or "disposed on" another element, it can be directly on the other element or intervening elements can also be present. When an element is referred to as being "connected", "coupled", or "attached" to another element, it can be directly connected, coupled, or attached to the other element, or intervening elements can be also present. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar expressions as used herein are for illustrative purposes only and are not meant to be limiting.

[0026] With the enhancement of domestic environmental protection and safety awareness, the application of vegetable oil transformer has been rapidly developed. As an important new type of environmentally friendly liquid insulation material, vegetable insulation oil has the advantages of high ignition point, excellent biodegradation performance, good electrical performance, wide raw material source and renewable, etc. Therefore, the application of vegetable oil transformer is becoming more and more widely. Because the viscosity of vegetable oil is large, the oil flow resistance is large, usually the height of the winding radial oil channel is increased to improve the heat dissipation performance, but the increase of the height of the radial oil channel will cause the deviation of the ampere-turn imbalance rate of the transformer winding to be large, causing the increase of the winding axial short circuit force, resulting in the reduction of the axial stability performance of the transformer winding, affecting the axial short circuit resistance of the transformer, and being not conducive to the safe and stable operation of the transformer.

[0027] In order to solve the above problems, as shown in Figure 1 An embodiment of the present application provides a method for improving the axial short circuit resistance of a vegetable oil transformer, which comprises the following steps:

[0028] Step 110: arranging the turns of the high-voltage winding and the low-voltage winding of the vegetable oil transformer in an upper-lower symmetrical structure, and placing the turns of the incomplete turns at the upper and lower ends of the winding;

[0029] Step 120: arranging the radial oil channels of the high-voltage winding and the low-voltage winding of the vegetable oil transformer in an upper-lower symmetrical structure, and placing the large oil channels at the upper and lower ends of the winding to ensure the symmetry of the oil channel arrangement.

[0030] Further, referring to Figure 2 The present application comprises fourteen winding turns 10, which are symmetrically arranged along the center line 50, and the adjacent winding turns 10 are radial oil channels. The upper and lower ends of the fourteen winding turns 10 are provided with three turns of incomplete turns 20, and the adjacent incomplete turns 20 are large oil channels 40.

[0031] According to the technical scheme, the turns of the high-voltage winding and the low-voltage winding are arranged in an up-down symmetrical structure, the radial oil channels of the high-voltage winding and the low-voltage winding are arranged in an up-down symmetrical structure, the large oil channel is arranged at the upper and lower ends of the winding, the symmetry of the oil channel arrangement is ensured, the ampere-turn imbalance of the winding can be effectively reduced, the radial magnetic leakage when the winding is short-circuited is reduced, the axial stress of the winding is reduced, the axial stability of the winding is improved, and the axial short-circuit resistance of the vegetable oil transformer is improved.

[0032] In some embodiments, in order to further improve the symmetry of the high-voltage winding and the low-voltage winding, after ensuring the symmetry of the oil channel arrangement, the method further comprises: adjusting the radial oil channel of the winding of the vegetable oil transformer, and aligning the center heights of the high-voltage winding and the low-voltage winding.

[0033] In some embodiments, before arranging the turns of the high-voltage winding and the low-voltage winding of the vegetable oil transformer in an up-down symmetrical structure, the method further comprises: dividing the winding turns into full-turn winding turns and non-full-turn winding turns. By distinguishing the full-turn winding turns and the non-full-turn winding turns in advance, errors in design are avoided.

[0034] In some embodiments, placing the non-full-turn winding turns at the upper and lower ends of the winding in the vegetable oil transformer comprises: placing non-full-turn winding turn A at the upper end of the winding, placing non-full-turn winding turn B at the lower end of the winding, and the number of turns and the length of non-full-turn winding turn A correspond to the number of turns and the length of non-full-turn winding turn B.

[0035] In some embodiments, in order to improve the axial short-circuit resistance of the transformer coil, after ensuring the symmetry of the oil channel arrangement, the method further comprises: compacting each winding turn.

[0036] In some embodiments, in order to avoid a large amount of heat generated by the conductor when the circumference is different, thereby reducing the performance of the winding, the cross-sectional area of the conductor in the high-voltage winding and the low-voltage winding in the present application is constant.

[0037] In some embodiments, a shielding layer is provided between the high-voltage winding and the low-voltage winding in the present application, which is beneficial to zeroing the electrical position between the coil surface and the high-voltage winding and the low-voltage winding that may cause high voltage, and preventing voltage breakdown. Specifically, the shielding layer comprises double-layer oil channel paper.

[0038] In some embodiments, the high-voltage winding in the present application has a middle outlet, thereby reducing the insulation level of the end of the winding.

[0039] In some embodiments, the number of turns and the length of the high-voltage winding in the present application are the same, the number of turns and the length of the low-voltage winding are the same, and the winding directions of the high-voltage winding and the low-voltage winding are the same.

[0040] In summary, the method for improving the axial short-circuit resistance of the vegetable oil transformer, by arranging the turns of the high-voltage winding and the low-voltage winding in an up-down symmetrical structure, arranging the radial oil channels of the high-voltage winding and the low-voltage winding in an up-down symmetrical structure, and placing the large oil channel at the upper and lower ends of the winding, ensures the symmetry of the oil channel arrangement, further adjusts the radial oil channel of the winding of the vegetable oil transformer, aligns the center heights of the high-voltage winding and the low-voltage winding, thereby effectively reducing the ampere-turn imbalance rate of the winding, reducing the radial magnetic leakage when the winding is short-circuited, reducing the axial stress of the wire cake, improving the axial stability of the winding, and improving the axial short-circuit resistance of the vegetable oil transformer.

[0041] The technical features of the above-described embodiments can be combined in any manner, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present disclosure.

[0042] The above-described embodiments only express several implementation manners of the present application, the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method of improving the axial short circuit resistance of a vegetable oil transformer, characterized in that, The method comprises: The full-turn and incomplete-turn winding cakes of the high-voltage winding and the low-voltage winding of the vegetable oil transformer are separated; The turns of the high-voltage winding and the low-voltage winding of the vegetable oil transformer are arranged in an up-down symmetric structure, and the incomplete-turn winding cakes are placed at the upper and lower ends of the winding; wherein, the incomplete-turn winding cake A is placed at the upper end of the winding, and the incomplete-turn winding cake B is placed at the lower end of the winding, the turns and the length of the incomplete-turn winding cake A correspond to the turns and the length of the incomplete-turn winding cake B; the radial oil channels of the high-voltage winding and the low-voltage winding are symmetrically distributed in an up-down direction; The radial oil channels of the high-voltage winding and the low-voltage winding of the vegetable oil transformer are arranged in an up-down symmetric structure, and the large oil channels are placed at the upper and lower ends of the winding to ensure the symmetry of the oil channel arrangement; the radial oil channels of the winding of the vegetable oil transformer are adjusted to align the center heights of the high-voltage winding and the low-voltage winding; Each winding cake is compressed; the cross-sectional area of the conductor in the high-voltage winding and the low-voltage winding is constant; a shielding layer is arranged between the high-voltage winding and the low-voltage winding; The high-voltage winding has a middle outlet.

2. The method of improving the axial short circuit resistance of a vegetable oil transformer of claim 1, wherein, The shielding layer comprises double-layer oil channel paper.

3. The method of improving the axial short circuit resistance of a vegetable oil transformer of claim 1, wherein, The turns and the length of the high-voltage winding are the same, the turns and the length of the low-voltage winding are the same, and the winding directions of the high-voltage winding and the low-voltage winding are the same.

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