A 500 kV single-phase autotransformer with on-load tap-changer

Abstract

The present invention discloses a 500 kV single-phase autotransformer with on-load voltage regulation, which includes: two side columns, a core column disposed between the side columns, a low-voltage coil, a voltage-regulating coil, a common coil, and a series coil that are sequentially arranged on the core column from the inside to the outside. The end outgoing terminal of the series coil is connected to the head outgoing terminal of the common coil, and the end outgoing terminal of the common coil is connected to the head outgoing terminal or the end outgoing terminal of the voltage-regulating coil. The present invention adopts the neutral point variable magnetic flux voltage regulation method for extra-large capacity transformers, which can better meet the power demand, reduce the space occupation and the investment in power grid construction, has a simpler structure and better processability, and has good application value in the power grid system.

Description

[0001] Application Field

[0002] The present invention relates to the field of transformers, and particularly to a 500 kV single-phase autotransformer with on-load voltage regulation. Background Art

[0003] At present, most 500 kV transformers in China adopt the no-excitation voltage regulation method. However, in some areas, on-load voltage regulation is still adopted due to electricity consumption needs. The voltage regulation coil is arranged on the side column, and the iron core column mainly adopts a single-phase three-column type. Among them, the low-voltage coil, the common coil, and the series coil are successively sleeved on the middle iron core column from the inside to the outside, and the voltage regulation coil and the exciting coil are sleeved on one side column. The disadvantages are that an exciting coil must be added, the number of turns of the voltage regulation coil is also twice that of the main column voltage regulation, the cost is relatively high under the same performance parameters, the copper consumption is large, and the distances from the middle iron core column to the two side columns are not equal, resulting in a center of gravity shift.

[0004] In view of the above problems, in the prior art, the voltage regulation coil is wound around the side column and the voltage regulation coil is arranged at the head end of the common coil, that is, constant magnetic flux voltage regulation. However, in this way, the voltage of the voltage regulation lead is high and the capacity of the on-load tap-changer is limited. In fact, with the rapid economic development, the electricity demand is still very large, and the capacity of the transformer also needs to increase accordingly. However, due to the limitation of the capacity of the on-load tap-changer, the capacity of the transformer cannot be increased. Summary of the Invention

[0005] The present invention overcomes the deficiency of the limited capacity of the on-load tap-changer in the prior art, and provides a 500 kV single-phase autotransformer with on-load voltage regulation. To achieve the above object, the technical solution adopted by the present invention is: a 500 kV single-phase autotransformer with on-load voltage regulation, characterized in that it includes: two side columns, an iron core column arranged between the side columns, a low-voltage coil, a voltage regulation coil, a common coil, and a series coil successively arranged on the iron core column from the inside to the outside, the end outgoing line terminal of the series coil is connected to the head outgoing line terminal of the common coil, and the end outgoing line terminal of the common coil is connected to the head outgoing line terminal or the end outgoing line terminal of the voltage regulation coil.

[0006] In a preferred embodiment of the present invention, the voltage level between the voltage regulation coil and the tap-changer does not exceed 110 kV.

[0007] In a preferred embodiment of the present invention, the low-voltage coil, the voltage regulation coil, the common coil, and the series coil are all made of self-adhesive transposed conductors.

[0008] In a preferred embodiment of the present invention, a plurality of oil guide plates are arranged on the low-voltage coil, the common coil, and the series coil, and the distance between adjacent oil guide plates from top to bottom increases successively.

[0009] In a preferred embodiment of the present invention, the low-voltage coil is a spiral end-inlet type; the voltage regulating coil is a double-layer spiral type or a double-layer cylindrical type; the common coil is a continuous end-inlet type, and an electrostatic plate is provided at the end of the leading-out end of the head of the common coil; the series coil is an inner-screen continuous middle-inlet type, and electrostatic plates are provided at both the upper end and the lower end of the series coil.

[0010] In a preferred embodiment of the present invention, the bottom of the voltage regulating coil includes a plurality of tap wires, and the tap wires are divided into two layers.

[0011] In a preferred embodiment of the present invention, the voltage regulating coil includes a plurality of voltage regulating turns from top to bottom. The voltage regulating turns include an inner leading-out end and an outer leading-out end. Adjacent two voltage regulating turns are connected through the inner leading-out end and the corresponding outer leading-out end to realize the serial connection of the plurality of voltage regulating turns in sequence, and a group of the tap wires is led out at the connection part between adjacent two voltage regulating coils.

[0012] In a preferred embodiment of the present invention, an upper yoke is fixedly arranged at the top of the iron core column, a lower yoke is arranged at the bottom of the iron core column, and the iron core column, the upper yoke and the lower yoke constitute the magnetic circuit of the transformer; upper magnetic shields are arranged at the tops of the series coil and the common coil, and lower magnetic shields are arranged at the bottoms of the series coil and the common coil.

[0013] In a preferred embodiment of the present invention, a plurality of vertically arranged and juxtaposed vertical strip magnetic shields are arranged on the inner wall of the oil tank.

[0014] In a preferred embodiment of the present invention, there is a height difference m between the upper end part of the voltage regulating coil and the upper end part of the common coil, and there is a height difference n between the lower end part of the voltage regulating coil and the lower end part of the common coil, and m≥n.

[0015] The present invention solves the defects existing in the background technology, and the present invention has the following beneficial effects:

[0016] The present invention adopts the neutral point variable magnetic flux voltage regulation method on the extra-large capacity transformer, realizes the single-phase capacity of the 500kV on-load voltage regulating transformer to be increased to 500000kVA under the existing on-load tap-changer capacity, better meets the power demand, reduces the space occupation and the investment in the power grid construction; at the same time, by a reasonable voltage regulating coil leading-out wire method, the problems of increased loss and increased temperature of the structural parts caused by the leakage magnetic flux of the lead wire under the non-rated tap condition are solved, and the problems of increased loss and increased temperature caused by the increased leakage magnetic flux due to the increase of the transformer capacity are solved through the leakage magnetic flux control structure of the cooperation between the magnetic shield of the transformer body and the vertical strip type oil tank magnetic shield; by reasonably selecting the coil wire type and reasonably designing the coil oil circuit, the problem of coil temperature rise is solved; by reasonably controlling the heights of the common coil and the voltage regulating coil, while meeting the insulation requirements of the product, the structure is simpler and the processability is better, and it has good application value in the power grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings of embodiments can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic diagram of the coil assembly of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the coil position of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention;

[0020] Figure 3 It is a schematic wiring diagram of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention;

[0021] Figure 4 It is a schematic wiring diagram of the regulating coil of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention;

[0022] Figure 5 It is a side view of the inside of the oil tank of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention;

[0023] Figure 6 It is a schematic diagram of the magnetic shielding assembly of a 500kV single-phase autotransformer with on-load tap-changer according to an embodiment of the present invention.

[0024] The following is an explanation of the reference numerals in the drawings: 101, side column; 102, core column; 201, low-voltage coil; 202, regulating coil; 2021, axial leading-out section; 2022, transverse leading-out section; 203, common coil; 204, series coil; 205, electrostatic plate; 301, upper yoke; 302, lower yoke; 401, upper magnetic shielding plate; 402, lower magnetic shielding plate; 403, vertical strip magnetic shielding plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner. Therefore, they only show the components related to the present invention. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0026] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the protection scope of the present application. In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0027] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood through specific circumstances.

[0028] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0029] As Figures 1-3 shown, a 500 kV single-phase autotransformer with on-load voltage regulation, which includes: two side columns 101, a core column 102 arranged between the side columns 101, a low-voltage coil 201, a regulating coil 202, a common coil 203, and a series coil 204 that are sequentially arranged on the core column 102 from the inside to the outside. The end outgoing terminal of the series coil 204 is connected to the head outgoing terminal of the common coil 203, and the end outgoing terminal of the common coil 203 is connected to the head outgoing terminal or the end outgoing terminal of the regulating coil 202.

[0030] Referring to Figure 1 and Figure 3As shown in the figure, in a 500 kV single-phase autotransformer with on-load tap-changer according to the present invention, since the single-phase three-column core structure 102 can well reduce the leakage magnetic flux of the coil while meeting the product technical parameters, thereby reducing the stray losses of the transformer. Therefore, the present invention still adopts the single-phase three-column core structure 102, but only the middle core column 102 is sleeved with coils, and the exciting coil of the original structure is cancelled. The coils are, from inside to outside, the low-voltage coil 201, the regulating coil 202, the common coil 203, and the series coil 204. At the same time, the volume of the transformer is reduced, and the cost is significantly reduced. Winding the regulating coil 202 on the core column 102 can, firstly, cancel the exciting coil, reduce the copper consumption, and lower the cost. And by setting the regulating coil 202 at the tail of the common coil 203, the voltage of the regulating coil 202, the regulating lead wire, and the tap-changer is less than 220 kV.

[0031] The voltage of the regulating coil 202 and the tap-changer is at most 110 kV. That is to say, the voltage of the regulating coil 202, the regulating lead wire, and the tap-changer is reduced from 220 kV in the prior art to below 110 kV. The current of the regulating coil 202, the regulating lead wire, and the tap-changer is the same as that of the common coil 203. The increase of the transformer capacity is no longer limited by the capacity of the on-load tap-changer. The product structure is simpler and the reliability is higher.

[0032] The low-voltage coil 201 is a helical type with end-inlet; the regulating coil 202 is a double-layer helical type or a double-layer cylindrical type; the common coil 203 is a continuous type with end-inlet, and an electrostatic plate 205 is arranged at the end of the leading-out end of the head of the common coil 203; the series coil 204 is an inner-screen continuous type with middle-inlet, and electrostatic plates 205 are arranged at both the upper end and the lower end of the series coil 204.

[0033] Specifically here, the low-voltage coil 201, the common coil 203, and the series coil 204 in the present invention have the same inlet mode as that in the prior art. The regulating coil 202 is a double-layer helical type or a double-layer cylindrical type. The double-layer helical coil has distinct structural characteristics. The head and tail leads are at the same end of the coil, arranged in a "∪" or "∩" shape, divided into inner and outer layers, and there are no solder joints in the connection between the two layers of wires. For large-capacity transformers, the double-layer helical coil can reduce the leakage magnetic flux density and reduce the stray losses.

[0034] The low-voltage coil 201, the regulating coil 202, the common coil 203, and the series coil 204 are all made of self-adhesive transposed conductors. What is not shown in the figure is that a number of oil guide plates are arranged on the low-voltage coil 201, the common coil 203, and the series coil 204, and the distance between adjacent oil guide plates from top to bottom increases in turn.

[0035] Here, all coils adopt self-adhesive transposed conductors, effectively controlling the axial and radial eddy current losses of the coils, effectively controlling the temperature difference between the coil and the oil, and at the same time, oil guiding plates are provided for the low-voltage coil 201, the common coil 203, and the series coil 204 to ensure smooth oil flow inside the coils, well controlling the temperature rise of the coils. Moreover, the number of oil guiding plates is larger in the place closer to the upper end. Since the heating phenomenon is more serious closer to the upper end, the oil guiding plates are reasonably arranged to increase the reliability of the transformer operation.

[0036] As Figure 5 shown, the bottom of the voltage regulating coil 202 includes several tap wires, which are divided into two layers.

[0037] Specifically, each tap wire of the voltage regulating coil 202 adopts an inner and outer layered structure in the axial lead-out section 2021, and an upper and lower layered structure in the transverse lead-out section 2022 after the lead-out end, solving the problems of local overheating and increased structural losses caused by the current superposition at the lead-out part of the voltage regulating coil 202 and in the voltage regulating leads during the operation of the transformer at non-rated taps.

[0038] Referring to Figure 4 shown, the voltage regulating coil 202 includes several voltage regulating turns from top to bottom. Each voltage regulating turn includes an inner lead-out end and an outer lead-out end. Adjacent two voltage regulating turns are connected through the inner lead-out end and the corresponding outer lead-out end to realize the sequential series connection of several voltage regulating turns. A set of tap wires is led out at the connection between adjacent two voltage regulating coils 202.

[0039] That is to say, in an embodiment of the present invention, by reasonably selecting the number of turns of the voltage regulating coil 202, the inner lead-out end and the outer lead-out end of the voltage regulating coil 202 are led out at the same position. For example, the inner lead-out end 2 and the outer lead-out end 1', the inner lead-out end 3 and the outer lead-out end 2', the inner lead-out end 4 and the outer lead-out end 3', the inner lead-out end 5 and the outer lead-out end 4', the inner lead-out end 6 and the outer lead-out end 5', the inner lead-out end 7 and the outer lead-out end 6', the inner lead-out end 8 and the outer lead-out end 7', the inner lead-out end 9 and the outer lead-out end 8', the inner lead-out end 10 and the outer lead-out end 9' are used to directly connect the leads of the inner and outer layer coils, avoiding the crossing of the voltage regulating leads, realizing the connection between the coil leads and the lead cables in the limited space, and also ensuring sufficient insulation distance, without the need to increase the distance between the coil and the oil tank to increase the space for the connection between the voltage regulating coil 202 and the leads and the safe insulation distance.

[0040] As Figure 5As shown in the figure, there is a height difference m between the upper end of the voltage regulating coil 202 and the upper end of the common coil 203, and a height difference n between the lower end of the voltage regulating coil 202 and the lower end of the common coil 203, and m≥n. Specifically, there is a certain distance between the upper end of the voltage regulating coil 202 and the upper end of the common coil 203, and between the lower end of the voltage regulating coil 202 and the lower end of the common coil 203, which reduces the mutual influence of the end magnetic fields and ensures reliable insulation between the end of the common coil 203 and the voltage regulating coil 202.

[0041] The upper yoke 301 is fixedly arranged at the top of the iron core column 102, and the lower yoke 302 is arranged at the bottom of the iron core column 102. The iron core column 102 is connected to the upper yoke 301 and the lower yoke 302 by 45-degree inclined joints; the upper magnetic shield 401 is arranged at the top of the common coil 203 and the series coil 204, and the lower magnetic shield 402 is arranged at the bottom of the common coil 203 and the series coil 204. A plurality of vertically arranged vertical bar magnetic shields 403 are arranged on the inner wall of the oil tank.

[0042] As the capacity of the transformer increases, the leakage magnetic flux of the coil also increases. An upper magnetic shield 401 and a lower magnetic shield 402 are arranged at the upper and lower ends of the coil, and a leakage magnetic flux control system with vertical bar magnetic shields 403 provides two paths for the coil leakage magnetic flux. One is the leakage magnetic flux loop formed by the upper magnetic shield plate 401 and the lower magnetic shield plate 402 through the upper and lower yokes 302 and two side yokes, and the other is the loop formed by the magnetic shields at the upper and lower ends of the transformer body and the vertical bar oil tank magnetic shield, which solves the problem of overheating of the structural parts of the iron core column 102 and the oil tank structure caused by the coil leakage magnetic flux.

[0043] In summary, the present invention adopts the method of neutral point variable magnetic flux voltage regulation on ultra-large capacity transformers, realizing the capacity of 500 kV on-load voltage regulating transformers to be increased to 500,000 kVA under the existing on-load tap-changer capacity, better meeting the power demand, reducing space occupation and investment in grid construction. At the same time, by reasonably arranging the outgoing line of the voltage regulating coil 202, the problems of increased loss and increased temperature of the structural parts caused by the leakage magnetic flux of the lead under non-rated tap conditions are solved. The leakage magnetic flux control structure formed by the cooperation of the magnetic shield of the transformer body and the vertical bar oil tank magnetic shield solves the problems of increased loss and increased temperature rise caused by the increase of the transformer capacity and the leakage magnetic flux. By reasonably selecting the coil wire type and reasonably designing the coil oil circuit, the problem of coil temperature rise is solved. By reasonably controlling the height of the common coil 203 and the voltage regulating coil 202, while meeting the insulation requirements of the product, the structure is simpler and the processability is better, which has good application value in the power grid system.

[0044] The above embodiments only represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A 500 kV single-phase autotransformer with on-load tap-changer, characterized in that, Including: Two side columns, a core column disposed between the side columns, a low-voltage coil, a voltage regulating coil, a common coil, and a series coil sequentially arranged on the core column from inside to outside. The end outgoing terminal of the series coil is connected to the head outgoing terminal of the common coil, and the end outgoing terminal of the common coil is connected to the head outgoing terminal or the end outgoing terminal of the voltage regulating coil. The low-voltage coil is a spiral type end-inlet, and the voltage regulating coil is a double-layer spiral type or a double-layer cylindrical type; the common coil is a continuous type end-inlet, and an electrostatic plate is provided at the end of the head outgoing terminal of the common coil; the series coil is an inner screen continuous type middle-inlet, and electrostatic plates are provided at both the upper end and the lower end of the series coil.

2. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 1, characterized in that: The voltage level between the voltage regulating coil and the tap changer does not exceed 110 kV.

3. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 1, characterized in that: The low-voltage coil, the voltage regulating coil, the common coil, and the series coil are all made of self-adhesive transposed conductors.

4. A 500 kV single-phase auto-transformer with on-load tap-changer according to claim 1, characterized in that: A number of oil guide plates are provided on the low-voltage coil, the common coil, and the series coil, and the distance between adjacent oil guide plates arranged from top to bottom increases sequentially.

5. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 1, characterized in that: The bottom of the voltage regulating coil includes a number of tap wires, and the tap wires are divided into two layers.

6. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 5, characterized in that: The voltage regulating coil includes a number of voltage regulating turns from top to bottom. The voltage regulating turns include an inner outgoing terminal and an outer outgoing terminal. Adjacent two voltage regulating turns are connected through the inner outgoing terminal and the corresponding outer outgoing terminal to realize the sequential series connection of a number of the voltage regulating turns, and a group of the tap wires is led out at the connection between adjacent two voltage regulating coils.

7. A 500 kV single-phase auto-transformer with on-load tap-changer according to claim 1, characterized in that: An upper yoke is fixedly provided at the top of the core column, a lower yoke is provided at the bottom of the core column, and the core column, the upper yoke, and the lower yoke constitute the magnetic circuit of the transformer; an upper magnetic shield is provided at the top of the series coil and the common coil, and a lower magnetic shield is provided at the bottom of the series coil and the common coil.

8. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 7, characterized in that: A number of vertically arranged and juxtaposed vertical strip magnetic shields are provided on the inner wall of the oil tank.

9. A 500 kV single-phase autotransformer with on-load tap-changer according to claim 1, characterized in that: There is a height difference m between the upper end of the voltage regulating coil and the upper end of the common coil, and a height difference n between the lower end of the voltage regulating coil and the lower end of the common coil, and m ≥ n.

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