Oil-immersed transformer for 66kV offshore wind turbine

Abstract

The oil-immersed transformer comprises an iron core, low-voltage coils, high-voltage coils and an oil tank, the iron core, the low-voltage coils and the high-voltage coils are all arranged in the oil tank, the low-voltage coils are arranged on corresponding core columns of the iron core in a sleeving mode, the high-voltage coils are arranged on the corresponding low-voltage coils in a sleeving mode, and the high-voltage coils are arranged in the oil tank in a sleeving mode. The height H2 of the low-voltage coil is larger than the height H1 of the high-voltage coil, the low-voltage coil is a foil type coil, the high-voltage coil comprises a coil upper section, a voltage regulating tapping section and a coil lower section which are sequentially arranged from top to bottom, the voltage regulating tapping section is an entangled continuous winding coil, and a low-voltage sleeve is arranged on the low-voltage side of the oil tank and connected with an external cable. The low-voltage coil is connected with the corresponding low-voltage sleeve, the high-voltage side of the oil tank is provided with a high-voltage sleeve connected with an external cable, and the high-voltage coil is connected with the corresponding high-voltage sleeve. According to the invention, the use requirement and the installation requirement of offshore wind power generation can be met, the voltage class can reach 66kV, and the capacity can reach 20MVA.

Description

Technical Field

[0001] The invention relates to the field of offshore wind power generation, in particular to an oil-immersed transformer for a 66kV offshore wind generator. Background Art

[0002] Transformers for offshore wind turbines are usually located in the nacelle of offshore wind turbines. Compared with transformers for onshore wind turbines, transformers for offshore wind turbines have more stringent requirements in terms of operational reliability and miniaturization. With the development of offshore wind power, large-capacity, high-voltage wind turbine generator sets have become an inevitable trend. The capacity of transformers for generators will reach more than 20MVA, and the requirements for short-circuit resistance and load loss are very strict. In the past, due to the small installed capacity of onshore wind power, small-capacity transformers were usually used, and their coil structure generally adopted a multi-layer cylindrical coil structure. However, this multi-layer cylindrical coil structure has the disadvantages of large interlayer voltage gradient, poor impact resistance, difficult to control coil size, insufficient winding compactness, easy axial collapse, and poor short-circuit resistance. It is not suitable for large-capacity, high-voltage offshore wind turbine generator sets.

[0003] In addition, the transformer for offshore wind turbines is installed in the nacelle. The rotation of blades and impellers, the vibration of the generator and gearbox in the nacelle, and the loads caused by environmental factors such as waves and sea breeze all affect the safe operation of the transformer. At the same time, explosions, oil leaks, and combustion are not allowed in offshore transformers. Summary of the invention

[0004] The purpose of the present invention is to provide a 66kV oil-immersed transformer for offshore wind turbines, which improves the transformer's short-circuit resistance, vibration resistance, explosion-proof and other performances, while also meeting the transformer's miniaturized design requirements and being able to meet the use and installation requirements of offshore wind power generation. Its voltage level can reach 66kV and its capacity can reach 20MVA.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A 66kV oil-immersed transformer for an offshore wind turbine comprises an iron core, a low-voltage coil, a high-voltage coil and an oil tank, wherein the iron core, the low-voltage coil and the high-voltage coil are all arranged in the oil tank, and the low-voltage coil is sleeved on the corresponding core column of the iron core, and the high-voltage coil is sleeved on the corresponding low-voltage coil, the height H2 of the low-voltage coil is greater than the height H1 of the high-voltage coil, and the low-voltage coil is a foil coil, and the high-voltage coil comprises a coil upper section, a voltage regulating tapping section and a coil lower section arranged in sequence from top to bottom, wherein the voltage regulating tapping section is a tangled continuously wound coil, a low-voltage bushing is provided on the low-voltage side of the oil tank to be connected to an external cable, and the low-voltage coil is connected to the corresponding low-voltage bushing, a high-voltage bushing is provided on the high-voltage side of the oil tank to be connected to the external cable, and the high-voltage coil is connected to the corresponding high-voltage bushing.

[0007] The upper section and the lower section of the coil are continuously wound coils, and both include a plurality of coil sections connected in series in sequence, the voltage regulating tapping section includes a plurality of positive sections and negative sections, and the inner diameter and outer diameter of each coil section, the positive section and the negative section are the same, and each coil section, the positive section and the negative section are stacked axially along the core column, and voltage regulating tapping terminals are provided on the positive section and the negative section and on the winding line between the corresponding side positive section and the negative section.

[0008] The low-voltage coil comprises multiple layers of low-voltage coil segments which are axially rolled by metal foil around corresponding core columns, and axial insulating oil passages are arranged between adjacent low-voltage coil segments.

[0009] The iron core is clamped and fixed in the oil tank by an upper clamp and a lower clamp, wherein a fixed hanger plate is provided on the upper side of the interior of the oil tank, and the upper clamp is connected to the fixed hanger plate, a positioning bowl is provided at the bottom of the inner side of the oil tank, and a positioning shaft is provided on the lower side of the lower clamp and fixed to the positioning bowl by epoxy resin casting, and a pressure plate is provided on the upper part of the low-voltage coil and high-voltage coil of each phase.

[0010] A reinforcing iron is provided on the outer side of the oil tank wall, and the reinforcing iron is an integrated U-shaped shape surrounding the side walls and the bottom of the oil tank. The outer edges of each reinforcing iron are connected by a back plate, and a transformer mounting fixing plate is provided on the upper end of the reinforcing iron.

[0011] A first pressure relief valve is provided on the high-pressure side of the oil tank, and the oil outlet of the first pressure relief valve is connected to an oil guide box arranged on the outside of the oil tank through a bellows. A second pressure relief valve is provided at the lower end of the low-pressure side of the oil tank, and the oil outlet of the second pressure relief valve is connected to an external oil guide pipe.

[0012] A copper shield is provided on the inner wall of the low-pressure side of the oil tank.

[0013] A low-voltage copper bar is provided on the low-voltage side of the oil tank, and the low-voltage coil is connected to the middle of the corresponding low-voltage copper bar, and both ends of the low-voltage copper bar are respectively connected to the corresponding low-voltage bushings.

[0014] An oil storage cabinet and a nitrogen box are arranged on the oil tank, and the oil storage cabinet is communicated with the oil tank through a pipeline, and the nitrogen box is communicated with the corresponding oil storage cabinet through a pipeline.

[0015] The high-voltage bushing is plugged in with a T-shaped front plug, and the T-shaped front plug is connected to an external cable.

[0016] The advantages and positive effects of the present invention are:

[0017] 1. The coil combination of the present invention can reduce the force acting on the iron yoke insulation at the end of the iron core in the case of a short circuit. The height of the inner low-voltage coil H2 is greater than the height of the outer high-voltage coil H1, which will form an unbalanced ampere-turn and generate a lateral leakage magnetic component and an axial electromotive force. The upper and lower tensions of the high-voltage coil are inward, and the axial thrust on the iron yoke insulation is very small or even zero. Although the upper and lower tensions of the low-voltage coil are outward, the low-voltage coil is formed by winding a whole piece of copper foil, and the upper and lower tensions it is subjected to cancel each other out. Therefore, the overall axial force of the high and low-voltage coils of the device is reduced, which is of great benefit to improving the short-circuit resistance of the transformer.

[0018] 2. The present invention can meet the design requirements of product miniaturization, wherein the voltage regulating tapping section in the middle of the high-voltage coil is a tangled continuously wound coil, which can reduce the number of voltage regulating tapping sections and thus reduce the size of the high-voltage coil. On the one hand, this can ensure that the height H1 of the outer high-voltage coil is less than the height H2 of the inner low-voltage coil, thereby achieving the lateral leakage magnetic component and axial electromotive force generated by unbalanced ampere-turns. On the other hand, it can also reduce the height of the entire coil combination, making the miniaturization design of the device body possible.

[0019] 3. Since the capacity of the present invention reaches 20MVA, the low-voltage rated current will reach more than 10,000 amperes, and the eddy current loss of the oil tank and structural parts such as the clamps caused by the leakage magnetic field is very large. Therefore, the present invention sets a copper shield on the inner wall of the low-voltage side of the oil tank to reduce the loss caused by the leakage magnetic field, and the low-voltage side lead structure of the present invention is a double-shunt copper bus and a double low-voltage bushing structure, which can reduce the current carrying capacity of the copper bus to half of the rated current, thereby reducing the loss caused by the leakage magnetic field to one-fourth of the original.

[0020] 4. The present invention clamps and fixes the iron core by means of an upper clamp and a lower clamp, and the upper clamp is fixedly connected to a fixed hanging plate arranged on the upper side of the interior of the oil tank, and a positioning shaft is provided on the lower side of the lower clamp, which is fixed by epoxy resin pouring with a positioning bowl of the oil tank bottom plate, so that the vibration resistance of the internal body of the product can be improved. At the same time, a pressure plate is provided on the upper part of each phase coil to ensure the coil is pressed tightly and improve the axial stability of the coil. In addition, the present invention provides an integral U-shaped reinforcing iron surrounding the two side walls and the bottom of the oil tank on the outside of the oil tank, and the outer edge of the reinforcing iron is connected by a back plate, which can prevent the oil tank from being torn when subjected to internal impact, and has an explosion-proof effect, and a transformer mounting fixing plate is provided on the upper end of the reinforcing iron to achieve stable installation of the transformer. These structures can greatly reduce the rotation of blades and impellers, the vibration of the generator and gearbox in the cabin, and the load caused by environmental factors such as waves and sea breeze, and meet the use requirements of offshore wind turbines.

[0021] 5. The present invention is provided with a pressure relief valve, a nitrogen tank and other structures on the outside of the oil tank to meet the requirements of explosion-proof and oil-leakage-proof of the seawater transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of the structure of the device body of the present invention,

[0023] Figure 2 for Figure 1 The cross-sectional view of the A-phase coil structure,

[0024] Figure 3 for Figure 2 A partial enlarged view of one side of the A-phase coil in the figure.

[0025] Figure 4a for Figure 3 Electrical connection schematic diagram of medium and high voltage coils,

[0026] Figure 4b for Figure 1 The electrical connection schematic diagram of the entire coil body.

[0027] Figure 5 for Figure 1 Left side view of the fuel tank.

[0028] Figure 6 for Figure 5 In the F direction view,

[0029] Figure 7 for Figure 5 Top view of the fuel tank.

[0030] Figure 8 It is a schematic diagram of the low-pressure lead structure on the low-pressure side of the fuel tank of the present invention.

[0031] Fig. 9 for Figure 1Installation diagram of the fuel tank.

[0032] Fig.10 for Figure 1 Schematic diagram of force analysis during the design of the center coil.

[0033] Among them, 1 is the iron core, 101 is the upper clamp, 102 is the lower clamp, 103 is the fixed hanger, 104 is the positioning shaft, 105 is the positioning bowl, 2 is the low-voltage coil, 201 is the low-voltage coil section, 202 is the axial insulating oil channel, 203 is the low-voltage bushing, 204 is the low-voltage copper bar, 3 is the high-voltage coil, 301 is the upper section of the coil, 3011 is the coil section, 302 is the voltage regulating tapping section, 3021 is the voltage regulating tapping section Connect the terminals, 3022 is the line correction, 3023 is the voltage regulating switch, 303 is the lower section of the coil, 4 is the oil tank, 401 is the copper shield, 402 is the first pressure relief valve, 403 is the bellows, 404 is the oil guide box, 405 is the second pressure relief valve, 406 is the reinforcing iron, 407 is the back plate, 408 is the transformer installation fixing plate, 5 is the high-voltage bushing, 6 is the T-type front plug, 7 is the oil storage cabinet, and 8 is the nitrogen box. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings.

[0035] like Figures 1 to 10 As shown, the present invention comprises an iron core 1, a low-voltage coil 2, a high-voltage coil 3 and an oil tank 4, wherein the iron core 1, the low-voltage coil 2 and the high-voltage coil 3 are all arranged in the oil tank 4, and the low-voltage coil 2 is sleeved on the corresponding core column of the iron core 1, and the high-voltage coil 3 is sleeved on the corresponding low-voltage coil 2, as shown in FIG. Figures 2-3 As shown, the low-voltage coil 2 is a foil coil, and the high-voltage coil 3 includes a coil upper section 301, a voltage regulating tapping section 302 and a coil lower section 303 which are arranged in sequence from top to bottom, wherein the coil upper section 301 and the coil lower section 303 are both conventional continuously wound coils, and the voltage regulating tapping section 302 is a tangled continuously wound coil. A low-voltage bushing 203 is provided on the low-voltage side of the oil tank 4 to be connected to an external cable, and the low-voltage coil 2 is connected to the corresponding low-voltage bushing 203. A high-voltage bushing 5 is provided on the high-voltage side of the oil tank 4 to be connected to an external cable, and the high-voltage coil 3 is connected to the corresponding high-voltage bushing 5.

[0036] like Figures 2-3 As shown, in the present invention, the height H2 of the inner low-voltage coil 2 is greater than the height H1 of the outer high-voltage coil 3, and a voltage-adjusting tapping section 302 is provided in the middle of the high-voltage coil 3. This combination can reduce the axial force caused by the short circuit, thereby improving the product's ability to resist short circuits. Specifically, since H2 is greater than H1, this will form an unbalanced ampere-turn and generate a lateral leakage magnetic component and an axial electromotive force. This is a well-known technology in the art, and can be found in "Principles of Transformer Design" pages 259-260, edited by Yin Kening. Therefore, Fig.10 As shown, this will cause downward tension F to be generated on the upper part of the outer high-voltage coil 3, upward tension F to be generated on the lower part of the outer high-voltage coil 3, upward tension F to be generated on the upper part of the inner low-voltage coil 2, and downward tension F to be generated on the lower part of the inner low-voltage coil 2. Since the upper and lower tensions F to which the outer high-voltage coil 3 is subjected are inward, that is, the axial thrust of the high-voltage coil 3 on the iron yoke insulation of the upper and lower cores 1 is very small or even zero, and the upper and lower tensions F to which the inner low-voltage coil 2 is subjected are outward, but since the low-voltage coil 2 is a foil winding, it is formed by a whole copper foil, and the whole copper foil will not deform. Therefore, the upper and lower tensions it is subjected to will also offset each other, which makes the axial force of the low-voltage coil 2 on the iron yoke insulation also very small. Therefore, this combination structure of coils with different heights reduces the force on the end iron yoke insulation in the case of a short circuit as a whole. In addition, the present invention designs the voltage regulating tapping section 302 in the middle of the outer high-voltage coil 3 as a tangled continuously wound coil. The tangled continuously wound coil can reduce the number of voltage regulating tapping sections, thereby reducing the size of the high-voltage coil 3 to ensure that H1 can be smaller than H2. At the same time, the size of the low-voltage coil 2 can also be reduced, thereby making the miniaturization design of the product possible. The tangled continuously wound coil is a well-known technology in the art. For example, the patent with announcement number CN202008910U discloses a 220kV-level coil tangled continuous structure, which includes multiple positive sections and reverse sections, and the corresponding side positive sections and reverse sections are connected by tangled lines. However, the present invention is used for voltage regulation, so if Figure 3 There is no connection line between the middle positive segment and the negative segment shown in the figure. In addition, the upper coil segment 301 and the lower coil segment 303 each include a plurality of coil segments 3011 arranged horizontally and connected in series in sequence. The inner diameter and outer diameter of the coil segment 3011 are the same as those of the positive segment and the negative segment of the entangled continuous winding coil, and each coil segment 3011, the positive segment, and the negative segment are stacked along the axial direction of the core column. Fig.10 As shown, since the upper and lower tensions F applied to the high voltage coil 3 are inward, this can also assist in the compaction of the various coil segments 3011, the positive segment, and the negative segment.

[0037] like Figures 2-3 As shown, the low-voltage coil 2 includes multiple layers of low-voltage coil segments 201 axially wound around corresponding core columns by metal foil, and axial insulating oil passages 202 are provided between adjacent low-voltage coil segments 201 .

[0038] like Figures 2-3 As shown, the voltage regulating tapping section 302 (tangled continuous winding coil) is provided with a voltage regulating tapping terminal 3021 on each positive section and reverse section and on the tangled line 3022 between the positive section and reverse section on the corresponding side. Figure 4a As shown, the terminals of the voltage regulating switch 3023 are respectively connected to any voltage regulating tapping terminal 3021 on the corresponding side to achieve voltage regulation, and the electrical connection of the low voltage coil 2 and the high voltage coil 3 of the entire body is as shown Figure 4bThe voltage regulating switch 3023 is a well-known technology in the art.

[0039] like Figure 1 As shown, in this embodiment, the iron core 1 is clamped and fixed in the oil tank 4 by an upper clamp 101 and a lower clamp 102, wherein a fixed hanger plate 103 is provided on the upper side of the interior of the oil tank 4, and the upper clamp 101 is connected to the fixed hanger plate 103, a positioning bowl 105 is provided on the bottom of the inner side of the oil tank 4, and a positioning shaft 104 is provided on the lower side of the lower clamp 102 and fixed to the positioning bowl 105 by epoxy resin pouring, which can improve the vibration resistance of the internal body of the product. In addition, a pressure plate is provided on the upper part of each phase coil to ensure the coil is pressed tightly and improve the axial stability of the coil, specifically: the upper part of each phase coil is fixed with a whole piece of high-strength laminated wood pressure plate using metal pressure nails, and the whole piece of high-strength laminated wood pressure plate is pressed against the coil of the body, thereby ensuring that each coil is pressed tightly and improving the axial stability of the coil. As Figure 6 and Fig. 9 As shown, in this embodiment, a reinforcing iron 406 is provided on the outer side of the box wall of the oil tank 4, and the outer edges of each reinforcing iron 406 are connected by a back plate 407 to ensure strength, and a transformer mounting plate 408 is welded on the upper end of the reinforcing iron 406, and the transformer mounting plate 408 is fixed to the fixing frame in the wind turbine cabin by bolts. The reinforcing iron 406 structure can ensure that the oil tank 4 will not be torn when subjected to internal impact, thereby preventing the oil tank 4 from exploding. In this embodiment, the reinforcing iron 406 is in an integrated U-shaped shape, which surrounds the side walls and the bottom of the oil tank 4.

[0040] Figures 5-6 As shown, the high-pressure side of the oil tank 4 is provided with a first pressure relief valve 402, and the oil outlet of the first pressure relief valve 402 is connected to an oil guide box 404 arranged outside the oil tank 4 through a bellows 403, and the lower end of the low-pressure side of the oil tank 4 is provided with a second pressure relief valve 405, and the oil outlet of the second pressure relief valve 405 is connected to an external oil guide pipe, and a pressure detection sensor can be provided inside the oil tank 4 as required. When it is detected that the internal pressure of the transformer oil tank 4 is too high, each pressure relief valve can be controlled by the control system to open and release the transformer oil to reduce the pressure, and at the same time, it can also prevent the internal failure of the transformer from causing oil and gas to spray out and cause external fire, thereby improving the explosion and fire resistance of the transformer. The pressure relief valve and pressure sensor are both commercially available products.

[0041] In addition, because the low voltage of offshore wind power transformers is generally 1.14kV, when the capacity reaches 20MVA, the low voltage rated current will reach more than 10,000 amperes, and the eddy current loss of the oil tank 4 and the clamps and other structural parts caused by the magnetic leakage generated is very large. Therefore, reducing the load loss is mainly to reduce the eddy current loss of the structural parts. To solve the above problems, Figure 5As shown, in this embodiment, a copper plate is welded on the inner wall of the low-pressure side of the oil tank 4 to form a copper shield 401, which can reduce the loss caused by magnetic leakage. Figure 8 As shown, a low-voltage copper bar 204 is provided on the low-voltage side of the oil tank 4, and the lead of the low-voltage coil 2 is connected to the middle of the low-voltage copper bar 204, and both ends of the low-voltage copper bar 204 are respectively connected to the corresponding low-voltage bushing 203. The low-voltage side lead structure of the present invention adopts a double-shunt copper bar and a double low-voltage bushing 203 structure, which can divide the rated current into two, that is, the copper bar carries half of the rated current, thereby reducing the loss caused by leakage magnetic flux to one-fourth of the original.

[0042] like Figures 6-7 The oil tank 4 is provided with an oil conservator 7 and a nitrogen tank 8, and the oil conservator 7 is connected to the oil tank 4 through a pipeline, and the nitrogen tank 8 is connected to the corresponding oil conservator 7 through a pipeline. The oil conservator 7 is connected to the inside of the oil tank 4 to provide a space for the transformer oil inside the oil tank 4 to change in volume with temperature, and the internal volume of the oil conservator 7 is reserved with a space for filling with dry nitrogen, and the nitrogen tank 8 fills the oil conservator 7 with nitrogen to form nitrogen protection.

[0043] like Figure 5 As shown, in this embodiment, the high-voltage bushing 5 is a cable terminal bushing, which is plugged into a T-shaped front plug 6, and the T-shaped front plug 6 is connected to an external 66kV cable. The T-shaped cable terminal outlet structure adopted in the present invention can improve the personal safety of operation and maintenance personnel, and also reduce the installation space for easy installation.

[0044] The working principle of the present invention is:

[0045] The transformers for wind power generation in the prior art are mainly used for onshore wind power generation equipment. Since the installed capacity of onshore wind power is small, the capacity of the transformers used is also small. Therefore, a conventional multi-layer cylindrical coil structure can be used. However, with the development of offshore wind power, the capacity of transformers for generators will reach more than 20MVA, and the requirements for short-circuit resistance and load loss are very strict. The conventional transformer structure can no longer meet the product performance requirements.

[0046] The present invention first designs the coil combination to improve the product's short-circuit resistance, specifically: the coil structure of the present invention, on the one hand, because the height H2 of the low-voltage coil 2 is greater than the height H1 of the high-voltage coil 3, the unbalanced ampere-turns will generate lateral leakage magnetic components and axial electromotive force, and as Fig.10As shown, the upper and lower tensions F applied to the high-voltage coil 3 are inward, so the axial thrust of the high-voltage coil 3 on the iron yoke insulation of the upper and lower core 1 is very small or even zero. Although the upper and lower tensions F applied to the low-voltage coil 2 are outward, since the low-voltage coil 2 is a foil winding, which is formed by winding a whole piece of copper foil and will not deform, the upper and lower tensions applied to it cancel each other out, thereby making the axial force of the low-voltage coil 2 on the iron yoke insulation also very small, so the overall axial force of the high and low voltage coils is reduced, which reduces the force on the iron yoke insulation at the end of the core 1 under short circuit conditions. On the other hand, since the voltage regulating tapping section 302 in the middle of the high-voltage coil 3 is a tangled continuously wound coil, the structure can reduce the number of voltage regulating tapping sections, thereby reducing the coil size and ensuring that H1 is less than H2, and at the same time, the height of the low-voltage coil 2 can be reduced in coordination, which makes the miniaturization design of the device body possible, thereby meeting the miniaturization requirements of transformers for offshore wind turbines due to installation space limitations.

[0047] In addition, because the low voltage of offshore wind power transformers is generally 1.14kV, when the capacity reaches 20MVA, the low voltage rated current will reach more than 10,000 amperes, and the eddy current loss of the oil tank 4 and the clamps and other structural parts caused by the leakage magnetic flux generated is very large. Therefore, to reduce the load loss, it is mainly to reduce the eddy current loss of the structural parts. Figure 5 As shown in FIG. 1 , a copper plate is welded on the inner wall of the low-pressure side of the oil tank 4 to form a copper shield 401, which can reduce the loss caused by magnetic leakage. Figure 8 As shown, the low-voltage side lead structure of the present invention is a double-branch copper busbar and a double low-voltage bushing 203 structure, which can divide the rated current into two, that is, the copper busbar carries half of the rated current, thereby reducing the loss caused by leakage magnetic flux to one-fourth of the original.

[0048] In order to ensure stable fixation, the iron core 1 of the body of the present invention is clamped and fixed in the oil tank 4 by an upper clamp 101 and a lower clamp 102, and the upper clamp 101 is fixedly connected to a fixed hanging plate 103 on the upper side of the inside of the oil tank 4. A positioning bowl 105 is provided at the bottom of the inner side of the oil tank 4, and a positioning shaft 104 is provided on the lower side of the lower clamp 102 to be fixed to the positioning bowl 105 by epoxy resin pouring. This can improve the vibration resistance of the internal body of the product. At the same time, a pressure plate is provided on the upper part of each phase coil to ensure the coil is pressed tightly and improve the axial stability of the coil. In addition, the present invention is provided on the outer side of the oil tank 4 A U-shaped reinforcing iron 406 is provided around the two side walls and the bottom of the box. The reinforcing iron 406 can improve the strength of the oil tank 4 and prevent the oil tank 4 from being torn when it is impacted from the inside. The outer edge of the reinforcing iron 406 is connected by a back plate 407 to ensure strength. A transformer mounting fixing plate 408 is provided on the upper end of the reinforcing iron 406 to achieve a stable installation of the transformer. These structures can greatly reduce the rotation of the blades and impellers, the vibration of the generator and gearbox in the cabin, and the load caused by environmental factors such as waves and sea breeze, and meet the use requirements of offshore wind turbines. In addition, the present invention is provided with a pressure release valve, a nitrogen box 8 and other structures on the outside of the oil tank 4 to meet the explosion-proof and oil-leakage-proof requirements of the seawater transformer.

Claims

1. A 66kV oil-immersed transformer for offshore wind turbines, characterized in that: The invention comprises an iron core (1), a low-voltage coil (2), a high-voltage coil (3) and an oil tank (4), wherein the iron core (1), the low-voltage coil (2) and the high-voltage coil (3) are all arranged in the oil tank (4), and the low-voltage coil (2) is sleeved on the corresponding core column of the iron core (1), and the high-voltage coil (3) is sleeved on the corresponding low-voltage coil (2), the height H2 of the low-voltage coil (2) is greater than the height H1 of the high-voltage coil (3), and the low-voltage coil (2) is a foil coil, and the high-voltage coil (3) is a foil coil. The invention comprises a coil upper section (301), a voltage regulating tapping section (302) and a coil lower section (303) which are arranged in sequence from top to bottom, wherein the voltage regulating tapping section (302) is a tangled continuously wound coil, a low-voltage bushing (203) is provided on the low-voltage side of the oil tank (4) and is connected to an external cable, and the low-voltage coil (2) is connected to the corresponding low-voltage bushing (203), and a high-voltage bushing (5) is provided on the high-voltage side of the oil tank (4) and is connected to an external cable, and the high-voltage coil (3) is connected to the corresponding high-voltage bushing (5).

2. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: The upper coil section (301) and the lower coil section (303) are continuously wound coils, and both the upper coil section (301) and the lower coil section (303) include a plurality of coil sections (3011) connected in series in sequence, the voltage regulating tapping section (302) includes a plurality of positive sections and negative sections, and the inner diameter and outer diameter of each coil section (3011), positive section and negative section are the same, each coil section (3011), positive section and negative section are stacked along the axial direction of the core column, and the positive section and the negative section and the corresponding side positive section and the negative section are provided with a voltage regulating tapping terminal (3021).

3. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: The low-voltage coil (2) comprises multiple layers of low-voltage coil segments (201) formed by axially winding metal foil around corresponding core columns, and axial insulating oil passages (202) are provided between adjacent low-voltage coil segments (201).

4. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: The iron core (1) is clamped and fixed in the oil tank (4) by an upper clamp (101) and a lower clamp (102), wherein a fixed hanging plate (103) is provided on the upper side of the interior of the oil tank (4), and the upper clamp (101) is connected to the fixed hanging plate (103), a positioning bowl (105) is provided on the bottom of the inner side of the oil tank (4), and a positioning shaft (104) is provided on the lower side of the lower clamp (102) and fixed to the positioning bowl (105) by epoxy resin casting, and a pressure plate is provided on the upper part of each phase low-voltage coil (2) and high-voltage coil (3).

5. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: A reinforcing iron (406) is provided on the outer side of the oil tank (4) wall, and the reinforcing iron (406) is in an integral U-shaped shape surrounding the side walls and the bottom of the oil tank (4), the outer edges of the reinforcing irons (406) are connected by a back plate (407), and a transformer mounting fixing plate (408) is provided on the upper end of the reinforcing iron (406).

6. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: A first pressure relief valve (402) is provided on the high-pressure side of the oil tank (4), and the oil outlet of the first pressure relief valve (402) is connected to an oil guide box (404) arranged outside the oil tank (4) through a bellows (403); a second pressure relief valve (405) is provided at the lower end of the low-pressure side of the oil tank (4), and the oil outlet of the second pressure relief valve (405) is connected to an external oil guide pipe.

7. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: A copper shield (401) is provided on the inner wall of the low-pressure side of the oil tank (4).

8. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1 is characterized in that: A low-voltage copper bar (204) is provided on the low-voltage side of the oil tank (4), and the low-voltage coil (2) is connected to the middle of the corresponding low-voltage copper bar (204), and both ends of the low-voltage copper bar (204) are respectively connected to the corresponding low-voltage bushing (203).

9. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1, characterized in that: An oil storage cabinet (7) and a nitrogen box (8) are provided on the oil tank (4), and the oil storage cabinet (7) is connected to the oil tank (4) through a pipeline, and the nitrogen box (8) is connected to the corresponding oil storage cabinet (7) through a pipeline.

10. The 66kV oil-immersed transformer for offshore wind turbine according to claim 1, characterized in that: The high-voltage bushing (5) is plugged into a T-shaped front plug (6), and the T-shaped front plug (6) is connected to an external cable.

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