Three-phase integrated 220kV low-frequency power transformer

Abstract

The utility model belongs to the field of power transformers, and relates to a three-phase integrated 220kV low-frequency power transformer, a high-voltage bushing and a low-voltage bushing are fixedly mounted on the outer side of the top of an oil tank, an iron core adopts a three-phase five-column structure, the diameter range of the iron core is between 900mm and 1670mm, the sectional area of a main yoke is 53-58% of the sectional area of a main column of the iron core, and the sectional area of the low-voltage bushing is 50-60% of the sectional area of the main column of the iron core. The sectional area of the iron core side column and the sectional area of the side yoke are 43%-48% of the sectional area of the iron core main column respectively, the sum of the sectional area of the main yoke and the sectional area of the side yoke is larger than the sectional area of the iron core main column, the diameter of the iron core lamination takes 7-10 mm as the stepping amount, the coils are sleeved on the peripheries of the iron core and the iron core main column and comprise a low-voltage coil and a high-voltage coil, and the high-voltage lead is connected with the high-voltage coil and the high-voltage sleeve. The cooling system is fixedly installed on the outer side of the side, close to the high-voltage bushing, of the oil tank, and the cooling system is communicated with the oil tank through a cooling mother pipe.

Description

Technical Field

[0001] This utility model belongs to the field of power transformer technology, specifically relating to a three-phase integrated 220kV low-frequency power transformer. Background Technology

[0002] As a core component of power transmission systems, power transformers utilize the principle of electromagnetic induction to transform AC voltage and current. Changes in the power grid frequency significantly impact power transformers, primarily affecting their core diameter and no-load losses. When the system frequency decreases from the power frequency to lower frequencies, on the one hand, to maintain the same capacity, the core cross-sectional area needs to be increased, resulting in a larger core diameter. This leads to an increase in the size and weight of the transformer body, coils, and tank. On the other hand, it causes a sharp increase in load losses and a decrease in no-load losses.

[0003] Therefore, it is necessary to develop solutions to the technical problems caused by the increase in the size and weight of power transformers due to the decrease in frequency, which in turn leads to the limitation of the external dimensions of power transformers and changes in no-load losses, so as to achieve a high-efficiency, compact and miniaturized design of low-frequency power transformers. Summary of the Invention

[0004] To solve the above-mentioned technical problems, this utility model provides a three-phase integrated 220kV low-frequency power transformer. The technical solution adopted by this utility model is as follows:

[0005] A three-phase integrated 220kV low-frequency power transformer includes a core, coils, high-voltage leads, low-voltage leads, an oil tank, high-voltage bushings, low-voltage bushings, and a cooling system. The high-voltage and low-voltage bushings are fixedly installed on the outer side of the top of the oil tank. The core adopts a three-phase five-column structure with a core diameter ranging from 900mm to 1670mm. The cross-sectional area of ​​the main yoke is 53-58% of the cross-sectional area of ​​the main column of the core, and the cross-sectional areas of the side columns and side yokes are 43-48% of the cross-sectional area of ​​the main column of the core, respectively. The sum of the cross-sectional areas of the main yoke and the side yoke is greater than the cross-sectional area of ​​the main column of the core. The diameter of the core laminations is incremented by 7-10mm. The coils are fitted around the outer periphery of the main column of the core. The coils include low-voltage coils and high-voltage coils. The high-voltage leads connect the high-voltage coils and the high-voltage bushings, and the low-voltage leads connect the low-voltage coils and the low-voltage bushings. The cooling system is fixedly installed on the outer side of the oil tank near the high-voltage bushings and is connected to the oil tank through a cooling header.

[0006] Preferably, the low-voltage coil adopts a continuous structure; the high-voltage coil adopts an inner-screen continuous structure with equal ampere-turns; both the low-voltage coil and the high-voltage coil use self-adhesive transposed wires.

[0007] Preferably, the core tie plate is vertically fixed to the core side column and the core main column by multiple layers of polyester binding straps. When the diameter of the core main column is in the range of [900mm, 1300mm], the thickness of the core tie plate is set to 12mm. When the diameter of the core main column is in the range of [1310mm, 1670mm], the thickness of the core tie plate is set to 16mm.

[0008] Preferably, the core pull plate includes a main pull plate and a pull plate supplementary plate, with pull plate supplementary plates welded to both ends of the main pull plate, and slots uniformly added to the non-contact surfaces of the pull plate supplementary plate and the main pull plate.

[0009] Preferably, the thickness of the pull plate is 6mm, and both the main pull plate and the pull plate supplement are made of low alloy steel Q690C with chamfered edges.

[0010] Preferably, a composite shield consisting of copper shielding and magnetic shielding is arranged on both the high-pressure and low-pressure sides inside the fuel tank, wherein the copper shielding is located on the upper part and top of the inner wall of the fuel tank, and the magnetic shielding is located on the lower middle part of the inner wall of the fuel tank.

[0011] Preferably, the oil tank adopts an arched lid barrel structure, and the outer side of the tank wall is welded with groove-type reinforcing ribs.

[0012] Preferably, both the high-voltage lead and the low-voltage lead are made of soft copper wire.

[0013] The beneficial effects of this utility model are:

[0014] This invention employs a three-phase, five-column laminated core design. By optimizing the cross-section of the core and yoke, the effective cross-sectional area of ​​the core is increased, the core diameter is optimized, and the coil and tank dimensions are reduced, thereby decreasing no-load and load losses during transformer operation. The cooling system design near the high-voltage bushing effectively reduces the weight and footprint of transformer accessories, achieving a compact, lightweight, and high-efficiency design for the 220kV low-frequency power transformer. The 220kV low-frequency power transformer designed in this invention operates at a frequency of 20Hz or 16.67Hz. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0016] Figure 1 This is a schematic diagram of the external structure of the low-frequency power transformer according to an embodiment of the present invention;

[0017] Figure 2 This is a schematic diagram of the core structure of the low-frequency transformer according to an embodiment of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of the pull plate main board according to an embodiment of the present utility model;

[0019] In the diagram: 1. Iron core, 2. Coil, 3. High-voltage lead, 4. Oil tank, 5. Cooling system, 6. Cooling main pipe, 7. High-voltage bushing, 8. Copper shield, 9. Low-voltage lead, 10. Oil tank magnetic shield, 11. Iron core side column, 12. Side yoke, 13. Iron core pull plate, 14. Main yoke, 15. Iron core main column, 16. Polyester binding strap, 17. Pull plate supplement plate, 18. Pull plate main plate, 19. Low-voltage bushing. Detailed Implementation

[0020] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0021] like Figure 1-3 As shown in the figure, this utility model embodiment discloses a three-phase integrated 220kV low-frequency power transformer for power transmission systems. The low-frequency power transformer includes an iron core 1, a coil 2, a high-voltage lead 3, a low-voltage lead 9, a high-voltage bushing 7, a low-voltage bushing 19, an oil tank 4, and a cooling system 5.

[0022] The core 1 adopts a three-phase, five-column structure, including three main core columns 15 and two side core columns 13. The diameter of the core 1 is controlled between 900mm and 1670mm, with the core lamination diameter incremented in 7.2mm steps. The number of core stages is designed to be 24-30. The appropriate number of core stages is matched to the diameter of the core 1; the larger the diameter of the core 1, the more core stages are required, in order to ensure that the core cross-section is as close to a circle as possible, thereby optimizing the magnetic circuit.

[0023] The upper and lower ends of the iron core main column 15 are respectively provided with main yokes 14, and the cross-sectional area of ​​the main yoke 14 is optimized to 53~58% of the cross-sectional area of ​​the iron core main column 15. The width of the yoke plate of the main yoke 14 is half the width of the iron core main column 15. The upper and lower ends of the iron core side column 11 are respectively provided with side yokes 12, and the cross-sectional area of ​​the side yoke 12 is 43~48% of the cross-sectional area of ​​the iron core side column 11. The width of the yoke plate of the side yoke 12 is 130mm smaller than the width of the yoke plate of the main yoke 14, which can effectively reduce the magnetic flux density in the iron yoke, and ultimately reduce the no-load loss coefficient to meet the requirement of lower no-load loss.

[0024] Compared to the traditional cross-sectional area, the optimized core of the same diameter in this embodiment increases the effective cross-sectional area of ​​core 1 and core column 15, thus increasing the core filling area under the same circumscribed circle. Given a fixed core area, the optimized core column diameter of core 1 in this embodiment can be reduced by approximately 5-10 mm, which can decrease the amount of raw materials such as copper, iron, and oil used in the transformer, thereby reducing overall material costs.

[0025] Coil 2 is mounted on the outer periphery of the iron core main column 15, including a high-voltage coil and a low-voltage coil. The high-voltage coil adopts an inner screen continuous structure, and the low-voltage coil adopts a continuous structure with an equal ampere-turn arrangement design. The coil wires are made of high-temperature resistant self-adhesive transposed wires, which improves the transformer's short-circuit withstand capability and reduces the additional losses of the coils.

[0026] The leads include a high-voltage lead 3 and a low-voltage lead 9. The high-voltage lead 3 is used to connect the high-voltage coil to the high-voltage bushing 7 located outside the oil tank 4, and the low-voltage lead is used to connect the low-voltage coil to the low-voltage bushing 19 located outside the oil tank 4. In this embodiment, both the high-voltage lead 3 and the low-voltage lead 9 are made of soft copper wire.

[0027] The oil tank 4 adopts an arched roof barrel structure. The outer wall of the oil tank 4 is reinforced with grooved reinforcing ribs to enhance mechanical strength. This structure offers high strength and effectively reduces transformer noise. The cooling system 5 is fixedly installed on the side of the oil tank 4 near the high-voltage bushing 7. The cooling system 5 is connected to the oil tank 4 via a cooling header 6, effectively reducing the weight and footprint of transformer accessories. The cooling system 5 can consist of several evenly arranged air coolers.

[0028] Furthermore, a composite shield consisting of copper shield 8 and magnetic shield 10 is arranged on both the high-voltage and low-voltage sides inside the oil tank 4. The composite shield can reduce stray losses during transformer operation and prevent overheating of structural components during operation. Specifically, the copper shield 8 is located on the upper part and top of the inner wall of the oil tank 4 to prevent overheating of the tank wall near the lead wires; the magnetic shield 10 is located on the lower middle part of the inner wall of the oil tank 4 and extends to both sides with the center of coil 1 as the reference, covering more than 80% of the projected area of ​​coil 1, reducing the leakage flux of coil 1 and thus reducing the risk of overheating of the oil tank 4.

[0029] By installing a cooling system 5 on one side of the high-voltage side and using a composite magnetic shielding design, the heat generation of coil 1 is reduced, thereby optimizing the transformer size.

[0030] The core tie plate 13 is fixedly installed on the core side column 11 and the core main column 15 by multiple layers of polyester binding straps 16. The width of the core tie plate 13 is determined by the width of the last stage of the core. The width of the core tie plate 13 installed on the core main column 15 is greater than the width of the core tie plate 13 installed on the core side column 11. Considering the different weights of transformer bodies with different diameters, using core tie plates 13 of the same thickness would result in some redundancy and waste. Through analysis and verification, combined with existing experience, tie plates of different thicknesses are configured for core laminations of different diameters. Specifically, when the diameter of the core main column 15 is in the range of [900mm, 1300mm], the thickness of the core tie plate 13 is set to 12mm; when the diameter of the core main column 15 is in the range of [1310mm, 1670mm], the thickness of the core tie plate 13 is set to 16mm.

[0031] To ensure the mechanical strength of the core tie plate 13, the core tie plate 13 is designed as a combination structure of a tie plate main board 18 and a tie plate supplementary board 17. The tie plate supplementary board 17 with a thickness of 6mm is welded to both ends of the tie plate main board 18. At the same time, in order to reduce stray losses and improve the operating efficiency of the transformer, slots are uniformly added to the non-contact surfaces of the tie plate supplementary board 17 and the tie plate main board 18. The number of slots is different according to the width of the tie plate supplementary board 17. The slot spacing is 60mm, the slot width is 5mm, and the slot length is the core window height minus 50mm. Care should be taken to avoid the grounding hole of the grounding shield. The tie plate main board 18 and the tie plate supplementary board 17 are both made of low alloy steel Q690C and are chamfered to ensure the core filling rate.

[0032] By optimizing the cross-section of the iron core yoke, reducing the thickness of the tie plate, and changing the material of the tie plate, this embodiment improves the effective cross-sectional area and mechanical strength of the iron core 1.

[0033] In this embodiment of the utility model, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.

[0034] Finally, it should be noted that the above embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model.

Claims

1. A three-phase integrated 220kV low-frequency power transformer, comprising an iron core (1), coils (2), high-voltage leads (3), low-voltage leads (9), an oil tank (4), high-voltage bushings (7), low-voltage bushings (19), and a cooling system (5), wherein the high-voltage bushings (7) and low-voltage bushings (19) are fixedly installed on the outer side of the top of the oil tank (4), characterized in that, The iron core (1) adopts a three-phase five-column structure. The diameter of the iron core (1) is between [900mm, 1670mm]. The cross-sectional area of ​​the main yoke (14) is 53~58% of the cross-sectional area of ​​the main column (15) of the iron core. The cross-sectional areas of the side columns (11) and side yokes (12) are 43~48% of the cross-sectional area of ​​the main column (15) of the iron core, respectively. The cross-sectional area of ​​the main yoke (14) + the cross-sectional area of ​​the side yoke (12) is greater than the cross-sectional area of ​​the main column (15) of the iron core, and the iron core is stacked. The diameter of the plate is stepped by 7~10mm. The coil (2) is fitted on the outer periphery of the iron core main column (15). The coil (2) includes a low-voltage coil and a high-voltage coil. The high-voltage lead (3) connects the high-voltage coil and the high-voltage bushing (7). The low-voltage lead (9) connects the low-voltage coil and the low-voltage bushing (19). The cooling system (5) is fixedly installed on the outside of the oil tank (4) near the high-voltage bushing (7). The cooling system (5) is connected to the oil tank (4) through the cooling main pipe (6).

2. The three-phase integrated 220kV low-frequency power transformer according to claim 1, characterized in that, The low-voltage coil adopts a continuous structure; the high-voltage coil adopts an inner-screen continuous structure with equal ampere-turns; both the low-voltage coil and the high-voltage coil use self-adhesive transposed wires.

3. A three-phase integrated 220kV low-frequency power transformer according to claim 1, characterized in that, The core tie plate (13) is vertically fixed on the core side column (11) and the core main column (15) by multiple layers of polyester binding straps (16). When the diameter of the core main column (15) is in the range of [900mm, 1300mm], the thickness of the core tie plate (13) is set to 12mm. When the diameter of the core main column (15) is in the range of [1310mm, 1670mm], the thickness of the core tie plate (13) is set to 16mm.

4. A three-phase integrated 220kV low-frequency power transformer according to claim 3, characterized in that, The core pull plate (13) includes a pull plate main plate (18) and a pull plate supplement plate (17). The pull plate supplement plate (17) is welded to both ends of the pull plate main plate (18). Grooves are uniformly added to the non-contact surfaces of the pull plate supplement plate (17) and the pull plate main plate (18).

5. A three-phase integrated 220kV low-frequency power transformer according to claim 4, characterized in that, The thickness of the pull plate supplement (17) is 6mm. The materials of the pull plate main plate (18) and the pull plate supplement (17) are both low alloy steel Q690C with chamfered edges.

6. A three-phase integrated 220kV low-frequency power transformer according to claim 1, characterized in that, A composite shield consisting of a copper shield (8) and a magnetic shield (10) is arranged on the high-pressure and low-pressure sides inside the oil tank (4), respectively. The copper shield (8) is located on the upper part and top of the inner wall of the oil tank (4), and the magnetic shield (10) is located on the lower middle part of the inner wall of the oil tank (4).

7. A three-phase integrated 220kV low-frequency power transformer according to claim 1, characterized in that, The oil tank (4) adopts an arched lid barrel structure, and the outer side of the tank wall of the oil tank (4) is welded with groove-type reinforcing ribs.

8. A three-phase integrated 220kV low-frequency power transformer according to claim 1, characterized in that, Both the high-voltage lead (3) and the low-voltage lead (9) are made of soft copper wire.

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