High-voltage coil structure of 66kV station transformer

Abstract

The utility model relates to a 66kV station transformer high-voltage coil structure which comprises four coil sections which are sequentially arranged from top to bottom, each coil section comprises a plurality of coil layers which are arranged in the radial direction and are sequentially connected in series, each coil section is formed by winding an enameled copper wire, and the enameled copper wire is wound on the coil sections. An interlayer insulator A is arranged between every two adjacent coil layers of each coil section, and an inter-section insulator is arranged between every two adjacent coil sections; a first outgoing line is arranged at the outer end of the first coil section on the uppermost side, the inner end of the first coil section is connected with the inner end of the second coil section adjacent to the lower side, a plurality of first tapping leads are arranged at the outer end of the second coil section, a second outgoing line is arranged at the outer end of the fourth coil section on the lowermost side, and the inner end of the fourth coil section is connected with the inner end of the third coil section adjacent to the upper side. And a plurality of second tapping leads are arranged at the outer end of the third coil section. According to the utility model, a two-section type high-voltage coil in the prior art is changed into a four-section type structure, so that the partial discharge test of a transformer product can be ensured to be qualified, and the production and manufacturing difficulty is reduced.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, specifically a high-voltage coil structure for a 66kV substation transformer. Background Technology

[0002] For 66kV station service transformers with an apparent power of 1000kVA and below, due to their high voltage of 66kV and the large number of turns in the high-voltage coil (up to several thousand turns), existing technologies typically employ a two-stage multi-layer cylindrical high-voltage coil structure, and the coil conductors are usually made of paper-insulated round copper wire. This structure has the following disadvantages:

[0003] I. With technological advancements, users' requirements for transformer partial discharge are decreasing. Currently, the partial discharge requirement for the high-voltage side of 66kV station service transformers is less than 100Pc, while the no-load current requirement is ≤0.3%. However, the existing two-stage high-voltage coil structure of 66kV station service transformers uses paper-insulated round copper wire with thick interlayer insulation, which makes it difficult to expel interlayer gas during transformer oil filling and vacuum treatment. This can easily lead to problems such as local cavities and air bubbles. At the same time, the penetration of insulating oil into the interlayer insulation is relatively poor, which can easily lead to a reduction in insulation performance and consequently cause the product to fail the partial discharge test.

[0004] Second, the interlayer voltage of 66kV station service transformers is high, so sufficient interlayer insulation thickness is required. However, the existing two-stage high-voltage coil structure and interlayer insulation thickness of 66kV station service transformers will cause the transformer's capacitive current to be too large, which is greater than the transformer's inductive current. This can easily lead to the no-load current being capacitive and having a large value. Currently, the main way to reduce the no-load current is to reduce the transformer's magnetic flux density, but this increases the cost of the transformer.

[0005] Third, the existing 66kV station service transformer has a two-stage high-voltage coil structure, and its high-voltage coil output end is usually equipped with an electrostatic plate. However, during the production process, the problem of amplitude deviation can easily occur when the electrostatic plate is surrounded, which increases the production difficulty and also increases the size of the transformer.

[0006] Patent CN118571621A discloses a coil structure for a 66kV high-capacity oil-immersed transformer for offshore wind power. This device adopts a conventional two-section high-voltage coil structure, which includes an upper half coil and a lower half coil, and the upper half coil and the lower half coil form a layered winding structure with upper and lower sections.

[0007] Patent CN211929255U discloses an axial irregular combination conductor suitable for power transformers above 66kV. This patent uses an irregular combination conductor installed at the end of the power transformer above 66kV to replace the traditional electrostatic plate. While reducing the electric field strength, it can also reduce space and shrink the transformer volume. However, this patent does not make any improvement to the high-voltage coil structure itself. Utility Model Content

[0008] The purpose of this utility model is to provide a high-voltage coil structure for a 66kV substation transformer, which changes the existing two-section high-voltage coil to a four-section structure, ensuring that the transformer product passes the partial discharge test and reducing the difficulty of production and manufacturing.

[0009] The objective of this utility model is achieved through the following technical solution:

[0010] A high-voltage coil structure for a 66kV substation transformer includes four coil segments arranged sequentially from top to bottom. Each coil segment includes multiple coil layers arranged radially and connected in series. Each coil segment is wound with enameled copper wire, and interlayer insulation A is provided between adjacent coil layers of each coil segment, and inter-segment insulation is provided between adjacent coil segments. The outer end of the uppermost first coil segment is provided with a first lead wire, and its inner end is connected to the inner end of the adjacent second coil segment below. The outer end of the second coil segment is provided with multiple first tap leads. The outer end of the lowermost fourth coil segment is provided with a second lead wire, and its inner end is connected to the inner end of the adjacent third coil segment above. The outer end of the third coil segment is provided with multiple second tap leads.

[0011] The first coil segment includes multiple coil layers A connected in series, and the second coil segment includes multiple coil layers B connected in series. The outermost coil layer A of the first coil segment is connected to the first lead wire, the innermost coil layer A of the first coil segment is connected to the innermost coil layer B of the second coil segment, and the outermost coil layer B of the second coil segment is connected to the corresponding first tap lead wire. Interlayer insulation A is provided between adjacent coil layers A and between adjacent coil layers B.

[0012] The third coil segment includes multiple coil layers C connected in series, and the fourth coil segment includes multiple coil layers D connected in series. The outer coil layers C of the third coil segment are connected to the corresponding second tap leads, the innermost coil layer C of the third coil segment is connected to the innermost coil layer D of the fourth coil segment, and the outermost coil layer D of the fourth coil segment is connected to the second lead. Interlayer insulation A is provided between adjacent coil layers C and between adjacent coil layers D.

[0013] The first lead is connected to the high-voltage bushing of the corresponding phase, the second lead is connected to the high-voltage coil of the next phase, and both the first tap lead and the second tap lead are connected to the tap changer.

[0014] The first coil segment, the second coil segment, the third coil segment, and the fourth coil segment are all located in the transformer oil tank, and the upper end of the transformer oil tank is provided with a high-voltage bushing and a tap changer. The first lead wire is connected to the corresponding high-voltage bushing through a corresponding connecting cable, and the first tap lead wire and the second tap lead wire are respectively connected to the tap changer through corresponding voltage regulating tap cables.

[0015] The upper end of the transformer tank is provided with a low-pressure bushing, a connecting pipe, a riser seat, and a tank cover evacuation valve. The lower end of the high-pressure bushing is connected to the corresponding riser seat, and the connecting pipe is provided with an evacuation valve at a position higher than the riser seat.

[0016] The advantages and positive effects of this utility model are as follows:

[0017] 1. This utility model changes the existing two-section high-voltage coil to a four-section structure, reducing the number of turns per section and the height of each section, while also reducing the thickness of the interlayer insulation. During vacuum oil injection, it is easier for interlayer gas to be discharged from the interlayer insulation, which can avoid problems such as cavities or air bubbles in the coil. It is also easier for the insulating oil to penetrate the interlayer insulation, ensuring insulation performance and thus ensuring that the transformer product passes the partial discharge test.

[0018] 2. In this invention, the first lead-out line, the first tap lead-out line, the second tap lead-out line, and the second lead-out line are all led out from the outer end of the corresponding coil segment, making manufacturing and connection more convenient. At the same time, the improved structure of this invention can reduce the capacitive current of the coil, so as to meet the no-load current requirement without reducing the magnetic flux density. Furthermore, the inner electrostatic plate can be eliminated, which can more effectively control the overall radial dimension of the product and avoid problems such as radial deviation when surrounding the electrostatic plate. This further reduces the difficulty of product manufacturing and effectively ensures the parameters and performance of the product.

[0019] 3. In addition to using the conventional vacuum valve on the box cover to create a vacuum, this utility model also sets up a vacuum valve on the connecting pipe at a position higher than the riser seat. By increasing the vacuum intensity and duration of the product, the vacuum inside the riser seat is guaranteed, thereby ensuring the oil immersion effect of the product and ensuring that there is no cavity inside the product, thus further guaranteeing that the product passes the partial discharge test. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model.

[0021] Figure 2 for Figure 1Enlarged view of point I in the image.

[0022] Figure 3 This is a schematic diagram of a two-stage high-voltage coil structure in the prior art.

[0023] Figure 4 for Figure 3 Enlarged view of point K in the image.

[0024] Figure 5 This is a schematic diagram of the wiring principle of the 66kV substation transformer that this utility model addresses.

[0025] Figure 6 This is a schematic diagram of the high-voltage turns of the 66kV substation transformer that this utility model addresses.

[0026] Figure 7 This is a schematic diagram of the lead connection of a 66kV station service transformer using this utility model.

[0027] Figure 8 for Figure 7 Front view of the 66kV substation transformer.

[0028] Figure 9 for Figure 8 A top view of the 66kV substation transformer.

[0029] Wherein, 1 is the first coil segment, 101 is coil layer A, 102 is the first lead-out wire, 2 is the second coil segment, 201 is coil layer B, 202 is the first tap lead-out wire, 3 is the third coil segment, 301 is coil layer C, 302 is the second tap lead-out wire, 4 is the fourth coil segment, 401 is coil layer D, 402 is the second lead-out wire, 5 is interlayer insulation A, 6 is inter-segment insulation, 7 is enameled copper wire, 8 is the upper coil segment, 801 is the first coil layer, and 802 is the upper coil group. 803 is the lower coil, 804 is lead wire A, 805 is the upper tap lead, 9 is the lower coil section, 901 is lead wire B, 902 is the lower tap lead, 10 is interlayer insulation B, 11 is interlayer insulation C, 12 is interlayer insulation D, 13 is paper-insulated copper wire, 14 is voltage regulating tap cable, 15 is connecting cable, 16 is tap changer, 17 is high-voltage bushing, 18 is box cover evacuation valve, 19 is connecting pipe evacuation valve, 20 is low-voltage bushing, and 21 is static plate. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] like Figures 1-2As shown, this utility model includes four coil segments arranged sequentially from top to bottom, and each coil segment includes multiple coil layers arranged radially and connected in series. Each coil segment is wound with enameled copper wire 7, and interlayer insulation A5 is provided between adjacent coil layers of each coil segment, and inter-segment insulation 6 is provided between adjacent coil segments. The outer end of the uppermost first coil segment 1 is provided with a first lead wire 102, and the inner end is connected to the inner end of the adjacent second coil segment 2 below. The outer end of the second coil segment 2 is provided with multiple first tap leads 202. The outer end of the lowermost fourth coil segment 4 is provided with a second lead wire 402, and the inner end is connected to the inner end of the adjacent third coil segment 3 above. The outer end of the third coil segment 3 is provided with multiple second tap leads 302. Figure 5 and Figure 7 As shown, the first lead 102 is connected to the high-voltage bushing 17 of the corresponding phase, the second lead 402 is connected to the high-voltage coil of the next phase, and the first tap lead 202 and the second tap lead 302 are both connected to the tap changer 16.

[0032] like Figure 1 As shown, the first coil segment 1 includes multiple coil layers A101 connected in series, and the second coil segment 2 includes multiple coil layers B201 connected in series. The outermost coil layer A101 of the first coil segment 1 is connected to the first lead 102, the innermost coil layer A101 of the first coil segment 1 is connected to the innermost coil layer B201 of the second coil segment 2, and the outermost coil layer B201 of the second coil segment 2 is connected to the corresponding first tap lead 202. Interlayer insulation A5 is provided between adjacent coil layers A101 and between adjacent coil layers B201.

[0033] like Figure 1 As shown, the third coil segment 3 includes multiple coil layers C301 connected in series, and the fourth coil segment 4 includes multiple coil layers D401 connected in series. The outer coil layers C301 of the third coil segment 3 are connected to the corresponding second tap leads 302. The innermost coil layer C301 of the third coil segment 3 is connected to the innermost coil layer D401 of the fourth coil segment 4. The outermost coil layer D401 of the fourth coil segment 4 is connected to the second lead 402. Interlayer insulation A5 is provided between adjacent coil layers C301 and between adjacent coil layers D401.

[0034] like Figure 7As shown, the first coil segment 1, the second coil segment 2, the third coil segment 3, and the fourth coil segment 4 are all located in the transformer tank. The upper end of the transformer tank is equipped with a high-voltage bushing 17 and a tap changer 16. The first lead-out wire 102 is connected to the corresponding high-voltage bushing 17 via a corresponding connecting cable 15. The first tap lead-out wire 202 and the second tap lead-out wire 302 are respectively connected to the tap changer 16 via corresponding voltage regulating tap cables 14. The tap changer 16 is a technology known in the art.

[0035] like Figures 8-9 As shown, the upper end of the transformer tank is equipped with a low-voltage bushing 20, a connecting pipe, a riser seat, and a tank cover evacuation valve 18. The lower end of the high-voltage bushing 17 is connected to the corresponding riser seat. The above structures are all known technologies in the art. However, this utility model sets a connecting pipe evacuation valve 19 on the connecting pipe at a position higher than the riser seat. In the past, transformer products only used the tank cover evacuation valve 18 when evacuating, which easily caused the insulation inside the riser seat to not achieve a complete vacuum. This would affect the oil immersion effect and thus affect the measured value of partial discharge of the product. This utility model adds a connecting pipe evacuation valve 19 and increases the product evacuation intensity and duration to ensure the vacuum inside the riser seat, thereby ensuring the oil immersion effect of the product, making the product free of cavities, and thus further ensuring that the product passes the partial discharge test.

[0036] The working principle of this utility model is as follows:

[0037] like Figure 5 As shown, the high-voltage side of the 66kV station service transformer targeted by this utility model is a delta connection, and as... Figure 6 As shown, the high-voltage side coil has a large number of turns per phase, reaching several thousand turns. In contrast, existing technologies, such as... Figure 3 As shown, a 66kV station service transformer typically employs a two-section high-voltage coil, comprising an upper coil section 8 and a lower coil section 9. Both the upper coil section 8 and the lower coil section 9 include multiple coil layers arranged radially. However, as... Figures 3-4 As shown, each coil segment of this two-section high-voltage coil structure includes a first coil layer 801 and a second coil layer. The second coil layer includes an upper coil group 802 and a lower coil group 803 that are staggered vertically. Therefore, the interlayer insulation structure of the two-section high-voltage coil includes three parts: interlayer insulation B10, interlayer insulation C11, and interlayer insulation D12. Figure 4As shown, one side of the interlayer insulation C11 contacts the corresponding upper coil 802, and the lower end contacts the corresponding lower coil 803. One side of the interlayer insulation D12 contacts the corresponding lower coil 803, and the upper end contacts the corresponding upper coil 802. In addition, each coil segment of the two-section high-voltage coil is wound with paper-insulated copper wire 13, so its total interlayer insulation thickness is relatively thick. Specifically, it consists of 0.45 mm turns of paper-insulated copper wire 13 insulation plus 9 layers of insulation (the sum of interlayer insulation B10, interlayer insulation C11, and interlayer insulation D12) of 0.13 mm thick, for a total thickness of 0.45 + 9 × 0. 13 = 1.62mm. In addition, since the upper coil segment 8 and the lower coil segment 9 of the two-section high-voltage coil have a large number of turns per layer, the axial height of a single coil segment will be relatively high. The above structure will make it relatively difficult to evacuate and vent the transformer product, and it is easy to have problems such as air and air bubbles. At the same time, since the total thickness of the interlayer insulation is relatively thick, the penetration of the insulating oil in the interlayer insulation is relatively poor, which can easily lead to a reduction in insulation performance. Therefore, the combined effect of the above factors can easily cause problems such as the transformer product failing the partial discharge test. Furthermore, the winding connection of the above interlayer insulation structure is relatively complex, which increases the production difficulty.

[0038] And such Figure 1 As shown, this invention replaces the existing two-section high-voltage coil with a four-section structure, reducing the number of turns per section and lowering the height of each section of the transformer coil. This facilitates the expulsion of interlayer gas from the inter-section insulation 6 during vacuum oil filling. Furthermore, the reduced number of turns per layer lowers the interlayer voltage, allowing the number of interlayer insulation A5 layers between adjacent layers of each coil section to be halved. Additionally, this invention replaces the paper-insulated copper wire 13 with enameled copper wire 7, further reducing the total thickness of the interlayer insulation. Specifically, the thickness of the 7 turns of enameled copper wire insulation is negligible, and the total thickness of the four 0.13mm thick interlayer insulation A5 layers is 4 × 0.13 = 0.52mm. This is significantly reduced compared to the 1.62mm total thickness of the existing transformer products, facilitating the expulsion of gas from the coil during vacuum oil filling. The reduced thickness of the interlayer insulation A5 also promotes the penetration of insulating oil, ensuring insulation performance and guaranteeing the transformer product's partial discharge test qualification.

[0039] Other examples Figure 3As shown, in order to ensure performance, the lead wire A804 of the two-stage high-voltage coil in the prior art is led out from the inner end of the upper coil section 8 and equipped with an electrostatic plate 21. The outer end of the upper coil section 8 is provided with an upper tap lead wire 805 connected to the tap changer 16, while the lead wire B901 connected to the next phase high-voltage coil is led out from the outer end of the lower coil section 9. The inner end of the lower coil section 9 leads out a lower tap lead wire 902 connected to the tap changer 16. The above structure is inconvenient to process and connect because the lead wires are led out from the inner and outer ends of the upper coil section 8 and the inner and outer ends of the lower coil section 9, respectively. At the same time, problems such as radial deviation are easy to occur when surrounding the electrostatic plate 21. All of these increase the difficulty of transformer product manufacturing.

[0040] and Figure 1 As shown, in this invention, the first lead-out line 102, the first tap lead-out line 202, the second tap lead-out line 302, and the second lead-out line 402 are all led out from the outer ends of the corresponding coil segments, making manufacturing and connection more convenient. At the same time, the improved structure of this invention can reduce the capacitive current of the coil, achieving the goal of meeting the no-load current requirement without reducing the magnetic flux density, and can eliminate the need for... Figure 3 The electrostatic plate 21 in the middle can more effectively control the overall dimensional dimensions of the product, reduce the difficulty of product manufacturing, and make the impedance value closer to the product requirements.

[0041] The specific analysis of how this invention can reduce coil capacitance current is shown below:

[0042] Capacitance C = ε × s / 4π × kd;

[0043] In the above formula, ε is the dielectric constant, s is the area of ​​the electrode plate, d is the distance between the electrode plates, and k is the electrostatic constant. For this invention, s is the area of ​​each coil segment. Due to the reduction in the thickness of the interlayer insulation A5, the total area s of each coil segment decreases, while d is the distance between two adjacent coil segments. Since this invention changes the two-segment to a four-segment configuration, the distance between two adjacent coil segments is reduced. Through actual testing, the capacitance of the four-segment series configuration of this invention is reduced by about 1 / 2 compared to the two-segment series configuration in the prior art. With the reduction in capacitance, the capacitive current is also reduced. Through actual testing, it can be seen that the measured value of the no-load current of previous transformer products is 0.27-0.29%, which is less than the current user requirement of ≤0.3%. Previous transformer products were prone to failure. However, the measured value of the no-load current of this invention is 0.2%, which can ensure that the current user's no-load current requirement is met, and the magnetic flux density can be appropriately increased.

[0044] Other examples Figures 8-9As shown, in addition to using the conventional vacuum valve 18 on the box cover to create a vacuum, this utility model also sets a vacuum valve 19 on the connecting pipe at a position higher than the riser seat. By increasing the vacuum intensity and duration of the product, the vacuum inside the riser seat is guaranteed, thereby ensuring the oil immersion effect of the product and eliminating the cavity phenomenon inside the product, thus further ensuring that the product passes the partial discharge test.

Claims

1. A high-voltage coil structure for a 66kV substation transformer, characterized in that: It includes four coil segments arranged from top to bottom, and each coil segment includes multiple coil layers arranged radially and connected in series. Each coil segment is made of enameled copper wire (7), and there is interlayer insulation A (5) between adjacent coil layers of each coil segment, and there is segment insulation (6) between adjacent coil segments. The outer end of the uppermost first coil segment (1) is provided with a first lead wire (102), and the inner end is connected to the inner end of the lower adjacent second coil segment (2). The outer end of the second coil segment (2) is provided with multiple first tap leads (202). The outer end of the lowermost fourth coil segment (4) is provided with a second lead wire (402), and the inner end is connected to the inner end of the upper adjacent third coil segment (3). The outer end of the third coil segment (3) is provided with multiple second tap leads (302).

2. The high-voltage coil structure of the 66kV substation transformer according to claim 1, characterized in that: The first coil segment (1) includes multiple coil layers A (101) connected in series, and the second coil segment (2) includes multiple coil layers B (201) connected in series. The outermost coil layer A (101) of the first coil segment (1) is connected to the first lead (102), the innermost coil layer A (101) of the first coil segment (1) is connected to the innermost coil layer B (201) of the second coil segment (2), and the outermost coil layer B (201) of the second coil segment (2) is connected to the corresponding first tap lead (202). Interlayer insulation A (5) is provided between adjacent coil layers A (101) and between adjacent coil layers B (201).

3. The high-voltage coil structure of the 66kV substation transformer according to claim 1, characterized in that: The third coil segment (3) includes multiple coil layers C (301) connected in series, and the fourth coil segment (4) includes multiple coil layers D (401) connected in series. The outer coil layer C (301) of the third coil segment (3) is connected to the corresponding second tap lead (302). The innermost coil layer C (301) of the third coil segment (3) is connected to the innermost coil layer D (401) of the fourth coil segment (4). The outermost coil layer D (401) of the fourth coil segment (4) is connected to the second lead (402). Interlayer insulation A (5) is provided between adjacent coil layers C (301) and between adjacent coil layers D (401).

4. The high-voltage coil structure of the 66kV substation transformer according to claim 1, characterized in that: The first lead (102) is connected to the high-voltage bushing (17) of the corresponding phase, the second lead (402) is connected to the high-voltage coil of the next phase, and the first tap lead (202) and the second tap lead (302) are both connected to the tap changer (16).

5. The high-voltage coil structure of the 66kV substation transformer according to claim 4, characterized in that: The first coil segment (1), the second coil segment (2), the third coil segment (3) and the fourth coil segment (4) are all located in the transformer tank, and the upper end of the transformer tank is provided with a high-voltage bushing (17) and a tap changer (16). The first lead (102) is connected to the corresponding high-voltage bushing (17) through the corresponding connecting cable (15), and the first tap lead (202) and the second tap lead (302) are respectively connected to the tap changer (16) through the corresponding voltage regulating tap cable (14).

6. The high-voltage coil structure of the 66kV substation transformer according to claim 5, characterized in that: The upper end of the transformer tank is provided with a low-pressure bushing (20), a connecting pipe, a riser seat and a tank cover evacuation valve (18), wherein the lower end of the high-pressure bushing (17) is connected to the corresponding riser seat, and the connecting pipe is provided with a connecting pipe evacuation valve (19) at a position higher than the riser seat.

Images