Single-phase high-voltage top outgoing line transformer for high altitudes

Abstract

The application discloses a single-phase high-voltage top outgoing line transformer for high altitude, which comprises a transformer oil tank and an oil pillow, wherein the heights of high-voltage bushings, medium-voltage bushings, neutral point bushings and low-voltage bushings on the transformer oil tank are set to the minimum; the oil pillow is arranged on one side of the transformer oil tank, and a round bar electrode is welded on the upper end of the oil pillow close to the edge of the high-voltage bushing; one pressure release valve is arranged on the transformer oil tank corresponding to the high-voltage bushing, and another pressure release valve is arranged on the transformer oil tank corresponding to the medium-voltage bushing; the oil pillow is independently arranged on one side of the transformer oil tank, so that the basic requirement of external insulation distance is ensured; the round bar electrode is arranged to further reduce the electric field intensity at the corner of the upper end of the oil pillow, so that the discharge caused by the over-high electric field intensity, external air ionization and breakdown is avoided; and the arrangement of the pressure release valve can further improve the explosion-proof capacity of the transformer.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, and more specifically to a single-phase high-voltage top-outgoing transformer for high-altitude applications. Background Technology

[0002] Due to the high voltage level, the safety and reliability of the high-voltage outgoing lines of 750kV transformers must be ensured. Traditional 750kV outgoing lines adopt an L-shaped riser structure. When a fault occurs at the outgoing line, the limited space inside the L-shaped riser causes the flammable gas generated by the fault to cause a rapid increase in internal pressure. When the pressure rises to the strength limit of the riser, an explosion and combustion will occur. Although the existing high-voltage top outgoing line structure can improve the anti-explosion and anti-flammation capability to a certain extent, in high-altitude areas, the thin air reduces the electrical strength of the air, increasing the difficulty of the external insulation design of transformers with top outgoing line structures.

[0003] To ensure the external insulation distance, the positions of external structural components (such as oil tanks and pipes) need to be adjusted. However, due to the size limitations of the transformer, the external structures such as oil tanks and pipes can meet the basic requirements for external insulation distance. In practice, the shape and position of the structure can generate a high electric field intensity on the structural components. This high electric field intensity can cause external air ionization and breakdown, leading to discharge.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] To address the aforementioned technical deficiencies, the present invention provides a single-phase high-voltage top-outgoing transformer for high-altitude applications, comprising a transformer tank and an oil conservator. The transformer tank is equipped with high-voltage bushings, medium-voltage bushings, neutral point bushings, and low-voltage bushings. The high-voltage bushings, medium-voltage bushings, neutral point bushings, and low-voltage bushings are internally connected to corresponding leads of the transformer. The height of the medium-voltage bushings, neutral point bushings, and low-voltage bushings is set to a minimum. The oil conservator is located on one side of the transformer tank and is fixed to the ground by an oil conservator bracket. The oil conservator is connected to the transformer tank via an oil conservator fixing support. A round rod electrode is welded to the upper end of the oil conservator near the edge of the high-voltage bushing. The oil conservator is connected to the interior of the transformer tank via a vent pipe. The transformer tank is equipped with two pressure relief valves, one corresponding to the high-voltage bushing and the other corresponding to the medium-voltage bushing.

[0006] Preferably, coolers are provided on both sides of the transformer oil tank, the coolers are connected to the inside of the transformer oil tank through pipelines, an oil pump is provided below the cooler, and a fan is provided on the side of the cooler.

[0007] Preferably, the transformer tank contains a transformer body, which includes a core, an upper clamp, a lower clamp, a main column tie plate, a side column tie plate, a first-column coil, and a second-column coil. The core is a four-column core structure. The upper part of the core is secured by the upper clamp, and the lower part of the core is secured by the lower clamp. The upper clamp and the lower clamp are connected by the main column tie plate and the side column tie plate. The first-column coil and the second-column coil are respectively fitted on the two main columns of the core.

[0008] Preferably, the I-coil includes coils A, B, and C arranged sequentially from the inside out, and the upper and lower parts of the I-coil are respectively provided with a first upper pressure ring and a first lower pressure ring; the II-coil includes coils D, E, F, and G arranged sequentially from the inside out, and the upper and lower parts of the II-coil are respectively provided with a second upper pressure ring and a second lower pressure ring.

[0009] Preferably, the upper end of coil A is provided with a first upper electrostatic ring, a first upper corner ring, and a first upper end ring pad from bottom to top, and the lower end of coil A is provided with a first lower electrostatic ring, a first lower corner ring, and a first lower end ring pad from top to bottom, to form an end insulation structure; the upper end of coil B is provided with a second upper corner ring and a second upper end ring pad from bottom to top, and the lower end of coil B is provided with a second lower corner ring and a second lower electrostatic ring from top to bottom, to form an end insulation structure; the upper end of coil C is provided with a third upper electrostatic ring, a third upper corner ring, and a third upper end ring pad from bottom to top, and the lower end of coil C is provided with a third lower electrostatic ring, a third lower corner ring, and a third lower end ring pad from top to bottom, to form an end insulation structure; The upper end of coil D is provided with a fourth upper electrostatic ring, a fourth upper corner ring, and a fourth upper end ring pad, and the lower end of coil D is provided with a fourth lower electrostatic ring, a fourth lower corner ring, and a fourth lower end ring pad, forming an end insulation structure; the upper end of coil E is provided with a fifth upper electrostatic ring, a fifth upper corner ring, and a fifth upper end ring pad, and the lower end of coil E is provided with a fifth lower corner ring, a fifth lower electrostatic ring, and a fifth lower end ring pad, forming an end insulation structure; the upper end of coil F is provided with a sixth upper electrostatic ring, a sixth upper corner ring, and a sixth upper end ring pad, and the lower end of coil F is provided with a sixth lower corner ring. Coil F and coil E share the fifth lower end ring pad, forming an end insulation structure; the upper end of coil G is provided with a seventh upper electrostatic ring, a seventh upper corner ring, and a seventh upper end ring pad, and the lower end of coil G is provided with a seventh lower electrostatic ring, a seventh lower corner ring, and a seventh lower end ring pad, forming an end insulation structure.

[0010] Preferably, the outer side of the C coil is provided with a first screen support strip, the C coil and the B coil are provided with a second screen support strip, the B coil and the A coil are provided with a third screen support strip; the outer side of the G coil is provided with a fourth screen support strip, the G coil and the F coil are provided with a fifth screen support strip, the F coil and the E coil are provided with a sixth screen support strip, and the E coil and the D coil are provided with a seventh screen support strip.

[0011] Preferably, both coil A and coil D are provided with paper tube support strips on their inner sides.

[0012] Preferably, the high-voltage output device is installed inside the transformer tank corresponding to the I-column coil and the core. The high-voltage output wire of the high-voltage output device is led out from the C-column of the I-column coil along the axial center and connected to the high-voltage bushing. The upper and lower output wires of the C-column are connected to the middle of the G-column through a high-voltage tie line. The upper and lower output wires of the G-column are connected to the switch tap selector through a first tie line. The E-column is a voltage regulating coil. Tap leads are led out from the upper and lower parts of the E-column and connected to the switch tap selector from the high-voltage side and low-voltage side of the transformer, respectively. The upper leads of coils B and F are neutral point leads, and the lower leads of coils B and F are second tie lines. The neutral point leads are connected to the neutral point bushing, and the second tie line is connected to the switch tap selector. Coils A and D are both low-voltage coils. The first low-voltage lead on the upper part of coil A and the second low-voltage lead on the upper part of coil D are respectively connected to the respective low-voltage bushings. The lower parts of coils A and D are interconnected through the low-voltage tie line. The medium-voltage lead is led out from the switch tap selector and connected to the medium-voltage bushing.

[0013] Preferably, the transformer oil tank corresponding to the high-voltage outgoing line device is provided with multiple layers of protective screens on the tank wall.

[0014] Preferably, the tank walls of the transformer oil tank corresponding to the I-column coil and the II-column coil are all provided with magnetic shielding screens.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention ensures the basic requirements of external insulation distance by independently setting the oil conservator on one side of the transformer oil tank. At the same time, the oil conservator bracket and the oil conservator fixed support realize the effective position fixation of the oil conservator and the transformer oil tank to meet the wind resistance effect at high altitudes. The setting of the round bar electrode further reduces the electric field intensity at the corner of the upper end of the oil conservator, avoiding the discharge caused by external air ionization and breakdown due to excessive electric field intensity. The setting of the pressure relief valve can also further improve the transformer's anti-explosion and anti-flammation capability. Attached Figure Description

[0016] Figure 1 This is a front view of the structure of the single-phase high-voltage top-outgoing transformer used at high altitudes; Figure 2 This is a top view of the structure of the single-phase high-voltage top-outgoing transformer used at high altitudes; Figure 3 This is a structural side view of the single-phase high-voltage top-outgoing transformer used at high altitudes. Figure 4 This is a structural view of the transformer body; Figure 5 This is a top view of the internal structure of the transformer tank; Figure 6 This is a structural view of the I-pillar coil; Figure 7 This is a structural view of the II-pillar coil; Figure 8 This is a schematic diagram of the internal lead wiring principle of a transformer.

[0017] The numbers in the image represent: 1-Transformer oil tank; 2-High voltage bushing; 3-Medium voltage bushing; 4-Neutral point bushing; 5-Low voltage bushing; 6-Oil conservator; 7-Ladder; 8-Gas connection pipe; 9-Cooler; 10-Pressure relief valve; 11-Gas relay; 12-Terminal box; 13-Quick-acting hydraulic relay; 14-Switch; 61-Round bar electrode; 621-Oil conservator bracket; 622-Oil conservator fixing support; 91-Oil pump; 92-Fan; 121-Thermometer dial; 1211-Temperature sensor; 141-Switch operating mechanism; 101-Core; 102-Upper clamp; 103-Lower clamp; 104-Main column pull plate; 105-Side column pull plate; 106-Column I coil; 107-Column II coil; 201-High voltage output device; 202- 203 - Medium voltage lead; 204 - Neutral point lead; 205 - Second low voltage lead; 206 - First low voltage lead; 207 - Switch tap selector; 208 - Tap lead; 209 - Connecting line; 201 - Magnetic shielding enclosure; 210 - Multi-layer enclosure; 301 - First upper pressure ring; 302 - First lower pressure ring; 303 - First enclosure support bar; 305 - Second enclosure support bar; 308 - Third enclosure support bar; 310 - First paper tube support bar; 401 - Second upper pressure ring; 402 - Second lower pressure ring; 403 - Fourth enclosure support bar; 405 - Fifth enclosure support bar; 406 - Sixth enclosure support bar; 407 - Seventh enclosure support bar; 408 - Second paper tube support bar; 1061 - Coil A; 1062 - Coil B; 1063 - Coil C ; 1071-D coil; 1072-E coil; 1073-F coil; 1074-G coil; 2011-High voltage tie line; 2012-First tie line; 2031-Second tie line; 2051-Low voltage tie line; 10611-First upper static ring; 10612-First upper corner ring; 10613-First upper end ring pad; 10614-First lower static ring; 10615-First lower corner ring; 10616-First lower end ring pad; 10621-Second upper corner ring; 10622-Second upper end ring pad; 10623-Second lower corner ring; 10624-Second lower static ring; 10631-Third upper static ring; 10632-Third upper corner ring; 10 633 - Third upper end ring pad; 10634 - Third lower static ring; 10635 - Third lower corner ring; 10636 - Third lower end ring pad; 10711 - Fourth upper static ring; 10712 - Fourth upper corner ring; 10713 - Fourth upper end ring pad; 10714 - Fourth lower static ring; 10715 - Fourth lower corner ring; 10716 - Fourth lower end ring pad; 10721 - Fifth upper static ring; 10722 - Fifth upper corner ring; 10723 - Fifth upper end ring pad; 10724 - Fifth lower corner ring; 10725 - Fifth lower static ring; 10731 - Sixth upper static ring; 10732 - Sixth upper corner ring; 10733 - Sixth upper end ring pad;10734 - Sixth lower corner ring; 10735 - Fifth lower end ring spacer; 10741 - Seventh upper static ring; 10742 - Seventh upper corner ring; 10743 - Seventh upper end ring spacer; 10744 - Seventh lower static ring; 10745 - Seventh lower corner ring; 10746 - Seventh lower end ring spacer. Detailed Implementation

[0018] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings. Example 1

[0019] like Figure 1 , Figure 2 and Figure 3 As shown, Figure 1 This is a front view of the structure of the single-phase high-voltage top-outgoing transformer used at high altitudes; Figure 2 This is a top view of the structure of the single-phase high-voltage top-outgoing transformer used at high altitudes; Figure 3 This is a structural side view of the single-phase high-voltage top-outgoing transformer used at high altitudes.

[0020] The single-phase high-voltage top-outgoing transformer for high altitudes according to the present invention includes a transformer tank 1 and an oil conservator 6. The transformer tank 1 is equipped with a high-voltage bushing 2, a medium-voltage bushing 3, a neutral point bushing 4, and a low-voltage bushing 5. The high-voltage bushing 2, the medium-voltage bushing 3, the neutral point bushing 4, and the low-voltage bushing 5 are internally connected to the corresponding leads of the transformer. The height of the medium-voltage bushing 3, the neutral point bushing 4, and the low-voltage bushing 5 is set to a minimum. The oil conservator 6 is located on one side of the transformer tank 1 and is fixed to the ground by an oil conservator bracket 621. The oil conservator 6 is fixedly supported by the oil conservator. 622 is connected to the transformer oil tank 1. A round bar electrode 61 is welded to the upper end of the oil conservator 6 near the edge of the high-voltage bushing 2 to further reduce the electric field strength at the corner of the upper end of the oil conservator 6. The oil conservator 6 is connected to the inside of the transformer oil tank 1 through a gas pipe 8 to adjust the oil level of the body. The transformer oil tank 1 is equipped with two pressure relief valves 10, one pressure relief valve 10 corresponding to the high-voltage bushing 2 and the other pressure relief valve 10 corresponding to the medium-voltage bushing 3. The pressure relief valves 10 are used to release the internal pressure that increases when the transformer fails, and there are pipelines to lead the oil to the ground.

[0021] The pressure relief valve 10 is installed at the high-voltage outlet to release pressure caused by a fault. Since the pressure relief valve 10 is close to the high-voltage outlet, it avoids the problem of poor pressure transmission caused by the internal structure of the transformer, so that the pressure relief valve 10 can really play its role.

[0022] The rated voltage of the high-voltage bushing 2 is 750kV. In order to ensure the insulation distance between the high-voltage bushing 2 and other bushings (the insulation distance is corrected according to the altitude, and the insulation distance between other bushings and structural components is also corrected according to the altitude), the height of the medium-voltage bushing 3, the neutral point bushing 4 and the low-voltage bushing 5 is reduced to the minimum.

[0023] Both the oil conservator bracket 621 and the oil conservator fixed support 622 are steel structure brackets, which have good structural strength after being connected to each other. The material is low-temperature resistant steel, which can meet the strength requirements of the oil conservator 6 under low temperature, strong wind and earthquake conditions, and at the same time ensure that the oil conservator 6 and the high-voltage bushing 2 have sufficient insulation distance.

[0024] A gas relay 11 is installed on the gas pipe 8 for relay protection in the case of transformer fault. The gas relay 11 has a protective cover to protect it from sand and dust.

[0025] Coolers 9 are installed on both sides of the transformer oil tank 1. The cooling capacity of the coolers 9 is calculated and designed according to the altitude. The coolers 9 are connected to the inside of the transformer oil tank 1 through pipelines. An oil pump 91 is installed below the coolers 9 to realize the oil flow between the inside of the transformer oil tank 1 and the coolers 9, thereby enhancing the internal heat dissipation capacity. A fan 92 is installed on the side of the coolers 9 to enhance the flow of external air and enhance the heat dissipation capacity of the coolers 9. The fan 92 is also equipped with a dustproof net to prevent wind and sand.

[0026] A switch 14 is arranged at one end of the transformer oil tank 1. The switch 14 is switched between different positions via a switch operating mechanism 141. A terminal box 12 is installed next to the switch operating mechanism 141. Various low-voltage components are placed inside the terminal box 12, including a thermometer dial 121, to prevent dust from affecting it. The terminal box 12 has a double-door structure and good dust protection. A fast-acting hydraulic relay 13 is installed next to the terminal box 12 for relay protection when the internal pressure of the transformer suddenly increases. A protective cover is installed on the relay to protect it from dust.

[0027] The transformer oil tank 1 is equipped with a temperature sensor 1211 on its top for detecting the transformer temperature, and a protective cover is installed on it to protect it from sand and dust. The transformer oil tank 1 is also equipped with a ladder 7 for personnel to climb to the top of the transformer for installation and maintenance.

[0028] To ensure the reliable operation of the transformer in areas with strong winds and sandstorms, this invention provides special considerations for relevant transformer components. Due to its height, the transformer bushing is significantly affected by wind and sand. Therefore, high-strength porcelain bushings with strong resistance to wind and sand abrasion are used, improving the bending resistance of the bushings to meet the strength requirements under a 50-year return period with a 10-meter height and a 10-minute average wind speed of 35 m / s, and also meeting the strength requirements under an earthquake intensity of 9 degrees. The surface of the bushing porcelain bushing has been thickened with a glaze layer to improve the insulator surface's resistance to sand and dust. The oil conservator 6, due to its height, has been structurally reinforced to meet the strength requirements under strong winds. To prevent cold brittleness in low-temperature environments, low-temperature resistant steel is used to ensure strength requirements under low-temperature conditions. To improve the wind and sand resistance of the cooler 9, a stainless steel dustproof mesh is used on the fan inlet side, improving the fan motor's protection level. To prevent dust accumulation on the cooler 9 fins from affecting heat dissipation, large-tube fins are used, increasing the fin spacing. To prevent wind and sand intrusion, terminal box 12 employs a double-door structure to ensure excellent sealing performance. To protect the thermometer dial 121, the thermometer is also placed inside terminal box 12. Other metering equipment is also designed with protective covers to prevent the effects of wind and sand. All metering equipment meets the IP65 protection rating, possessing excellent waterproof and dustproof performance. To meet the requirements for operation in low-temperature environments, low-temperature resistant seals are used.

[0029] This invention ensures the basic requirements of external insulation distance by independently setting the oil conservator 6 on one side of the transformer tank 1. At the same time, the oil conservator bracket 621 and the oil conservator fixing support 622 effectively fix the positions of the oil conservator 6 and the transformer tank 1 to meet the wind resistance requirements at high altitudes. The setting of the round bar electrode 61 further reduces the electric field strength at the corner of the upper end of the oil conservator 6, avoiding discharge caused by external air ionization and breakdown due to excessive electric field strength. The setting of the pressure relief valve 10 can also further improve the transformer's anti-explosion and anti-flammation capability. Example 2

[0030] The transformer tank 1 contains the transformer body, such as Figure 4 and Figure 5 As shown, Figure 4 This is a structural view of the transformer body; Figure 5 This is a top view of the internal structure of the transformer tank.

[0031] The transformer core includes a core 101, an upper clamp 102, a lower clamp 103, a main column tie plate 104, a side column tie plate 105, an I-column coil 106, and an II-column coil 107. The core 101 is a four-column core structure. The upper part of the core 101 is secured by the upper clamp 102, and the lower part of the core 101 is secured by the lower clamp 103. The upper clamp 102 and the lower clamp 103 are connected by the main column tie plate 104 and the side column tie plate 105. The I-column coil 106 and the II-column coil 107 are respectively mounted on the two main columns of the core 101. For a 750kV transformer, the I-column coil 106 and the II-column coil 107 are 750kV coil structures, and the coil heat dissipation structure has been designed and optimized according to the altitude.

[0032] like Figure 6 and Figure 7 As shown, Figure 6 This is a structural view of the I-pillar coil; Figure 7 This is a structural view of the II column coil.

[0033] The I-column coil 106 includes coil A 1061, coil B 1062 and coil C 1063 arranged sequentially from the inside to the outside. The upper and lower parts of the I-column coil 106 are respectively provided with a first upper pressure ring 301 and a first lower pressure ring 302 for axially pressing the I-column coil 106. The II-column coil 107 includes a D coil 1071, an E coil 1072, an F coil 1073, and a G coil 1074 arranged sequentially from the inside to the outside. The upper and lower parts of the II-column coil 107 are respectively provided with a second upper pressure ring 401 and a second lower pressure ring 402 for axially pressing the II-column coil 107.

[0034] Specifically, the upper end of coil A 1061 is provided with a first upper electrostatic ring 10611, a first upper corner ring 10612, and a first upper end ring pad 10613, arranged sequentially from bottom to top. The lower end of coil A 1061 is provided with a first lower electrostatic ring 10614, a first lower corner ring 10615, and a first lower end ring pad 10616, arranged sequentially from top to bottom, to form an insulating structure at the end and to transmit the clamping force. The first upper electrostatic ring 10611 and the first lower electrostatic ring 10614 serve to uniformly distribute the electric field at the end. The first upper corner ring 10612 and the first lower corner ring 10615 serve to guide oil flow and separate oil gaps.

[0035] The upper end of coil B 1062 is provided with a second upper corner ring 10621 and a second upper end ring pad 10622 from bottom to top. The lower end of coil B 1062 is provided with a second lower corner ring 10623 and a second lower electrostatic ring 10624 from top to bottom, forming an insulating structure at the end and simultaneously transmitting clamping force. The second lower electrostatic ring 10624 serves to uniformly distribute the electric field at the end. The second upper corner ring 10621 and the second lower corner ring 10623 serve to guide oil flow and separate oil gaps.

[0036] The upper end of the C-coil 1063 is provided with a third upper electrostatic ring 10631, a third upper corner ring 10632, and a third upper end ring pad 10633, arranged sequentially from bottom to top. The lower end of the C-coil 1063 is provided with a third lower electrostatic ring 10634, a third lower corner ring 10635, and a third lower end ring pad 10636, arranged sequentially from top to bottom, forming an insulating structure at the end and simultaneously transmitting clamping force. The third upper electrostatic ring 10631 and the third lower electrostatic ring 10634 serve to uniformly distribute the electric field at the end. The third upper corner ring 10632 and the third lower corner ring 10635 serve to guide oil flow and separate oil gaps.

[0037] The upper end of the D coil 1071 is provided with a fourth upper electrostatic ring 10711, a fourth upper corner ring 10712, and a fourth upper end ring pad 10713. The lower end of the D coil 1071 is provided with a fourth lower electrostatic ring 10714, a fourth lower corner ring 10715, and a fourth lower end ring pad 10716, forming an insulating structure at the end and simultaneously transmitting clamping force. The fourth upper electrostatic ring 10711 and the fourth lower electrostatic ring 10714 serve to uniformly distribute the electric field at the end. The fourth upper corner ring 10712 and the fourth lower corner ring 10715 serve to guide oil flow and separate oil gaps.

[0038] The upper end of the E coil 1072 is provided with a fifth upper electrostatic ring 10721, a fifth upper corner ring 10722, and a fifth upper end ring pad 10723. The lower end of the E coil 1072 is provided with a fifth lower corner ring 10724, a fifth lower electrostatic ring 10725, and a fifth lower end ring pad 10735 (shared with the F coil 1073), forming an insulating structure at the end and simultaneously transmitting clamping force. The fifth upper electrostatic ring 10721 and the fifth lower electrostatic ring 10725 serve to uniformly distribute the electric field at the end. The fifth upper corner ring 10722 and the fifth lower corner ring 10724 serve to guide oil flow and separate oil gaps.

[0039] The upper end of the F coil 1073 is provided with a sixth upper electrostatic ring 10731, a sixth upper corner ring 10732, and a sixth upper end ring pad 10733. The lower end of the F coil 1073 is provided with a sixth lower corner ring 10734. The F coil 1073 and the E coil 1072 share the fifth lower end ring pad 10735, forming an insulating structure at the end and simultaneously transmitting clamping force. The sixth upper electrostatic ring 10731 serves to uniformly distribute the electric field at the end. The sixth upper corner ring 10732 and the sixth lower corner ring 10734 serve to guide oil flow and separate oil gaps.

[0040] The upper end of the G coil 1074 is provided with a seventh upper electrostatic ring 10741, a seventh upper corner ring 10742, and a seventh upper end ring pad 10743. The lower end of the G coil 1074 is provided with a seventh lower electrostatic ring 10744, a seventh lower corner ring 10745, and a seventh lower end ring pad 10746, forming an insulating structure at the end and simultaneously transmitting clamping force. The seventh upper electrostatic ring 10741 and the seventh lower electrostatic ring 10744 serve to uniformly distribute the electric field at the end. The seventh upper corner ring 10742 and the seventh lower corner ring 10745 serve to guide oil flow and separate oil gaps.

[0041] The outer side of coil C 1063 is provided with a first protective strip 303, which constitutes the external insulation structure of the coil. A second protective strip 305 is provided between coil C 1063 and coil B 1062, which constitutes the insulation structure between the coils and also serves a supporting function. A third protective strip 308 is provided between coil B 1062 and coil A 1061, which constitutes the insulation structure between the coils and also serves a supporting function.

[0042] A fourth surrounding support strip 403 is provided on the outer side of the G coil 1074, forming an external insulation structure for the coil. A fifth surrounding support strip 405 is provided between the G coil 1074 and the F coil 1073, forming an insulation structure between the coils and also providing support. A sixth surrounding support strip 406 is provided between the F coil 1073 and the E coil 1072, forming an insulation structure between the coils and also providing support. A seventh surrounding support strip 407 is provided between the E coil 1072 and the D coil 1071, forming an insulation structure between the coils and also providing support.

[0043] The inner side of coil A 1061 is provided with a first paper tube support strip 310, which serves to support the coil, making it more round and forming an effective heat dissipation oil channel. The inner side of coil D 1071 is provided with a second paper tube support strip 408, which serves to support the coil, making it more round and forming an effective heat dissipation oil channel.

[0044] The B coil 1062, C coil 1063, D coil 1071, E coil 1072, F coil 1073, and G coil 1074 are all equally divided into an upper heat dissipation area, a middle heat dissipation area, and a lower heat dissipation area along the axial direction. The upper heat dissipation area, the middle heat dissipation area, and the lower heat dissipation area each occupy one-third of the axial length of the corresponding coil. The height of the inter-segment oil passage is appropriately increased for the upper heat dissipation area and the lower heat dissipation area to improve the heat dissipation capacity of the coil.

[0045] When designing the coil, it is essential to ensure an effective and unobstructed circulation path within the coil, allowing hot oil to rise and cold oil to fall. Since the coil temperature is not linearly distributed during actual transformer operation, the oil temperature at hot spots may be much higher than the average oil temperature. Therefore, the linear path must be rationally arranged according to design standards and the temperature distribution characteristics within the coil.

[0046] To ensure the transformer's heat dissipation performance at high altitudes, the coil's internal insulation structure, low-loss design, oil flow distribution, and unobstructed oil flow channels were optimized. The coil's own heat dissipation capacity was guaranteed by calculating the oil flow velocity in each winding, the width of the main oil channels (inner and outer diameters), and the transverse oil channels between winding sections. Regarding external heat dissipation, the cooler's capacity calculation considered the impact of reduced air density at high altitudes on heat dissipation efficiency. The cooling capacity was calculated and corrected based on the air density corresponding to the altitude, ensuring sufficient capacity margin. Example 3

[0047] like Figure 8 As shown, Figure 8This is a schematic diagram of the internal lead wiring principle of the transformer. The high-voltage output device 201 is installed inside the transformer tank 1, corresponding to the I-column coil 106 and the core 101. The high-voltage output wire of the high-voltage output device 201 is led out from the C-column 1063 of the I-column coil 106 along the axial center and connected to the high-voltage bushing 2. After the upper and lower output wires of the C-column 1063 are connected, they are connected to the middle of the G-column 1074 via the high-voltage connecting line 2011. The upper and lower output wires of the G-column 1074 are connected to the switch tap selector 206 via the first connecting line 2012. The E-column 1072 is a voltage regulating coil. Tap leads 207 are led out from both the upper and lower parts of the E-column 1072 and connected to the switch tap selector 206 from the high-voltage side and low-voltage side of the transformer, respectively. The B... The upper leads of coil 1062 and F coil 1073 are neutral point leads 203, and the lower leads of B coil 1062 and F coil 1073 are second connecting lines 2031. The neutral point lead 203 is connected to the neutral point bushing 4, and the second connecting line 2031 is connected to the switch tap selector 206. Both A coil 1061 and D coil 1071 are low-voltage coils. The first low-voltage lead 205 on the upper part of A coil 1061 and the second low-voltage lead 204 on the upper part of D coil 1071 are respectively connected to the respective low-voltage bushings 5. The lower parts of A coil 1061 and D coil 1071 are connected to each other through the low-voltage connecting line 2051. The medium-voltage lead 202 is led out from the switch tap selector 206 and connected to the medium-voltage bushing 3.

[0048] The leads of the G coil 1074 and the E coil 1072 are both connected to the switch tap selector 206, thereby achieving mutual connection; the leads of the B coil 1062, the E coil 1072 and the G coil 1074 are all connected to the switch tap selector 206, thereby achieving mutual connection; by switching the switch tap selector 206, the number of turns of the E coil 1072 is changed, thereby achieving voltage regulation function.

[0049] A multi-layered screen 210 is provided on the tank wall of the transformer tank 1 corresponding to the high-voltage outgoing line device 201 to increase the insulation margin.

[0050] The transformer tank 1 corresponding to the I-column coil 106 and the II-column coil 107 is provided with a magnetic shielding screen 209 to shield the leakage magnetic field incident into the tank wall and at the same time ensure the insulation between the coil and the tank.

[0051] The high-voltage 750kV outgoing line of this invention adopts a top-outgoing structure. By placing the 750kV outgoing line device inside the oil tank and arranging a multi-layer oil gap structure on the side wall of the oil tank, the insulation reliability of the outgoing line position is improved. With the 750kV outgoing line device placed inside the oil tank, when a discharge fault occurs at the outgoing line, a large amount of flammable gas will be generated. Due to the expanded pressure release space, the rate of pressure increase is slowed down, and the pressure is borne by the oil tank wall. The large tank wall area allows for more even pressure distribution. Furthermore, the weld seams of the oil tank are reinforced, and materials with a high yield strength ratio are used. While ensuring the structural strength of the oil tank, it is also necessary to ensure that the oil tank has a certain degree of toughness, giving it a certain expansion capacity to adapt to the deformation of the oil tank caused by pressure increase. This ensures that the oil tank will not explode, crack, or leak, thereby increasing the overall explosion-proof and fire-resistant capability of the transformer structure and minimizing the losses caused by faults.

[0052] After adopting the high-voltage top-outlet structure, due to the increased compactness of the structure, to ensure the external insulation of the transformer at an altitude of 3500 meters, a 750kV bushing suitable for an altitude of 4000 meters was first selected. The external insulation of this bushing was modified for dry arc distance and creepage distance at an altitude of 4000 meters. The bushing itself has good insulation performance. The external insulation of the other bushings also needs to be modified according to the altitude. To ensure the external insulation requirements of the high-voltage bushing 2 and the oil tank 6, the oil tank is placed parallel to the outside of the transformer and supported by a separate foundation and support components, thereby increasing the air gap between the oil tank 6 and the bushing. The height of the riser of the medium-voltage, low-voltage, and neutral point bushing 4 is reduced to the minimum, and the height of the connecting pipe 8 and the oil tank 6 is also reduced to avoid the high-voltage parts of the high-voltage bushing 2, ensuring the air gap between them. All structural components should be lowered to the zero potential position of the high-voltage bushing as much as possible. If they are not at the zero potential position, the external insulation (voltage corrected according to the poster) of the high-voltage bushing 2 and structural components should be tested by electric field analysis. For example, for the high-voltage bushing 2 and the oil conservator 6, since the position of the oil conservator 6 is relatively high, the electrode shape of the oil conservator 6 has been optimized and a shielding electrode has been added to ensure that the electric field values ​​on the bushing side and the oil conservator 6 side are controlled within the electric field strength that causes corona discharge, and have a certain safety margin. For medium-voltage, low-voltage, and neutral point bushing 4, due to the lower voltage level, the external insulation of other structural components is relatively easy to meet.

[0053] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A single-phase high-voltage top-outgoing transformer for high-altitude applications, characterized in that, The system includes a transformer tank and an oil conservator. The transformer tank is equipped with high-voltage bushings, medium-voltage bushings, neutral point bushings, and low-voltage bushings. The high-voltage bushings, medium-voltage bushings, neutral point bushings, and low-voltage bushings are internally connected to the corresponding leads of the transformer. The height of the medium-voltage bushings, neutral point bushings, and low-voltage bushings is set to a minimum. The oil conservator is located on one side of the transformer tank and is fixed to the ground by an oil conservator bracket. The oil conservator is connected to the transformer tank by an oil conservator fixing support. A round bar electrode is welded to the upper end of the oil conservator near the edge of the high-voltage bushing. The oil conservator is connected to the inside of the transformer tank through a vent pipe. The transformer tank is equipped with two pressure relief valves, one corresponding to the high-voltage bushing and the other corresponding to the medium-voltage bushing.

2. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 1, characterized in that, Coolers are installed on both sides of the transformer oil tank. The coolers are connected to the inside of the transformer oil tank through pipelines. An oil pump is installed below the cooler, and a fan is installed on the side of the cooler.

3. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 1, characterized in that, The transformer tank contains a transformer body, which includes a core, an upper clamp, a lower clamp, a main column tie plate, a side column tie plate, a first-column coil, and a second-column coil. The core is a four-column core structure. The upper part of the core is secured by the upper clamp, and the lower part of the core is secured by the lower clamp. The upper and lower clamps are connected by the main column tie plate and the side column tie plate. The first-column coil and the second-column coil are respectively mounted on the two main columns of the core.

4. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 3, characterized in that, The I-coil includes coils A, B, and C arranged sequentially from the inside out, and a first upper pressure ring and a first lower pressure ring are respectively provided at the top and bottom of the I-coil; the II-coil includes coils D, E, F, and G arranged sequentially from the inside out, and a second upper pressure ring and a second lower pressure ring are respectively provided at the top and bottom of the II-coil.

5. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 4, characterized in that, The upper end of coil A is provided with a first upper electrostatic ring, a first upper corner ring, and a first upper end ring pad from bottom to top. The lower end of coil A is provided with a first lower electrostatic ring, a first lower corner ring, and a first lower end ring pad from top to bottom, forming an insulation structure at the end. The upper end of coil B is provided with a second upper corner ring and a second upper end ring pad from bottom to top. The lower end of coil B is provided with a second lower corner ring and a second lower electrostatic ring from top to bottom, forming an insulation structure at the end. The upper end of coil C is provided with a third upper electrostatic ring, a third upper corner ring, and a third upper end ring pad from bottom to top. The lower end of coil C is provided with a third lower electrostatic ring, a third lower corner ring, and a third lower end ring pad from top to bottom, forming an insulation structure at the end. The upper end of coil D is provided with a fourth upper electrostatic ring, a fourth upper corner ring, and a fourth upper end ring pad, and the lower end of coil D is provided with a fourth lower electrostatic ring, a fourth lower corner ring, and a fourth lower end ring pad, forming an end insulation structure; the upper end of coil E is provided with a fifth upper electrostatic ring, a fifth upper corner ring, and a fifth upper end ring pad, and the lower end of coil E is provided with a fifth lower corner ring, a fifth lower electrostatic ring, and a fifth lower end ring pad, forming an end insulation structure; the upper end of coil F is provided with a sixth upper electrostatic ring, a sixth upper corner ring, and a sixth upper end ring pad, and the lower end of coil F is provided with a sixth lower corner ring. Coil F and coil E share the fifth lower end ring pad, forming an end insulation structure; the upper end of coil G is provided with a seventh upper electrostatic ring, a seventh upper corner ring, and a seventh upper end ring pad, and the lower end of coil G is provided with a seventh lower electrostatic ring, a seventh lower corner ring, and a seventh lower end ring pad, forming an end insulation structure.

6. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 5, characterized in that, The outer side of coil C is provided with a first screen support strip, the C coil and the B coil are provided with a second screen support strip, the B coil and the A coil are provided with a third screen support strip; the outer side of coil G is provided with a fourth screen support strip, the G coil and the F coil are provided with a fifth screen support strip, the F coil and the E coil are provided with a sixth screen support strip, and the E coil and the D coil are provided with a seventh screen support strip.

7. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 6, characterized in that, Both coil A and coil D have paper tube support strips on their inner sides.

8. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 4, characterized in that, The high-voltage output device is installed inside the transformer tank corresponding to the I-column coil and the core. The high-voltage output wire of the device is led out axially from the C-column of the I-column coil and connected to the high-voltage bushing. The upper and lower output wires of the C-column are connected to the middle of the G-column via a high-voltage tie line. The upper and lower output wires of the G-column are connected to the switch tap selector via a first tie line. The E-column is a voltage regulating coil. Tap leads are led out from both the upper and lower parts of the E-column and connected to the switch tap selector from the high-voltage side and low-voltage side of the transformer, respectively. The upper leads of coil B and coil F are neutral point leads, and the lower leads of coil B and coil F are second tie lines. The neutral point leads are connected to the neutral point bushing, and the second tie line is connected to the switch tap selector. Coil A and coil D are both low-voltage coils. The first low-voltage lead on the upper part of coil A and the second low-voltage lead on the upper part of coil D are respectively connected to the respective low-voltage bushings. The lower parts of coil A and coil D are interconnected through the low-voltage tie line. The medium-voltage lead is led out from the switch tap selector and connected to the medium-voltage bushing.

9. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 8, characterized in that, The transformer oil tank corresponding to the high-voltage outgoing line device is provided with multiple layers of protective screens on the tank wall.

10. The single-phase high-voltage top-outgoing transformer for high altitudes as described in claim 9, characterized in that, The transformer tank walls corresponding to the I-column coil and the II-column coil are all equipped with magnetic shielding screens.

Images