Integrated pouring axial split dry-type transformer

Abstract

The utility model discloses an integrated casting axial split dry-type transformer which comprises an iron core, a coil assembly and a cooling fan, the coil assembly is provided with a low-voltage coil and a high-voltage coil, two sections of low-voltage coils are wound on the iron core in the vertical direction and on the periphery of the iron core, and a low-voltage casting body is integrally cast on the two sections of low-voltage coils; more than two even-number sections of high-voltage coils are wound on the vertical direction of the iron core and the periphery of the low-voltage coil, the plurality of sections of high-voltage coils are equally divided into an upper part and a lower part, the winding directions of the high-voltage coils of the upper part and the lower part are opposite, and a high-voltage pouring body is integrally poured on the high-voltage coils; the cooling fan is arranged below the low-pressure pouring body and the high-pressure pouring body and supplies air upwards from the lower portion of each pouring body for heat dissipation. Therefore, the heat dissipation efficiency of the coils and the mechanical strength and sudden short circuit resistance of each coil are improved, and the manufacturing cost is reduced.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to an integral cast axially split dry-type transformer. Background Technology

[0002] Transformers are the core components of the substation section in a power system. Transformers can be classified into dry-type transformers and oil-immersed transformers according to their cooling methods. Among them, dry-type transformers are transformers in which the iron core and coils are not immersed in insulating liquid. They have advantages such as low power consumption, high efficiency, moisture resistance, flame retardancy, no pollution, and convenient maintenance. They have been widely used in wind power generation, photovoltaic power generation, and energy storage industries.

[0003] Dry-type transformers typically consist of several main parts, including the core, coils, and insulation materials. The insulation materials are mostly made of inorganic materials such as epoxy resin, cast into a casting to wrap the coils and core to isolate current, prevent electric arcs, and provide fire resistance. The coils are divided into high-voltage coils and low-voltage coils, and both high-voltage and low-voltage coils are divided into upper and lower sections and wound around the core from the outside in.

[0004] For example, the Chinese utility model patent with announcement number CN201868198U and patent name "Double-Split Dry-Type Step-Up Transformer for Photovoltaic Power Generation" includes an iron core, coils, and a support frame. The coils are three-phase, with an upper winding and a lower winding arranged axially along the iron core of each phase coil. The upper and lower windings are arranged sequentially from the outside to the inside as a primary winding, a shielding coil, and a secondary winding. The primary winding leads of the two primary windings in the upper and lower windings are connected in parallel to a high-voltage control cabinet through a copper plate. The secondary winding leads of the two secondary windings in the upper and lower windings are respectively led out and connected to two inverters. The leads of the two shielding coils in the upper and lower windings are respectively connected to the upper clamping assembly and the lower clamping assembly at the upper and lower ends of the iron core through a copper sheet.

[0005] However, the existing technology still has the following defects: In existing axially split dry-type transformers, the high-voltage coil and the low-voltage coil are usually made into two coils of equal capacity arranged independently, one above the other. Moreover, the two coils arranged independently need to be wound and cast separately, and the two coils need to be supported by a pad. In the past, this arrangement of the high-voltage coil and the low-voltage coil independently arranged vertically was very complicated in terms of coil winding and insulation casting. The transformer was also large in size and faced the problem of insufficient mechanical strength. In addition, when the bottom cooling fan blew air to cool the transformer, the coils arranged independently were separated by the pad in the middle and leaked air outward, or were blocked by the middle pad and could not blow air to cool the upper coil, which affected the heat dissipation effect. Utility Model Content

[0006] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide an integrated cast axial split dry-type transformer.

[0007] The purpose of this utility model is achieved by the following technical solution: an integrated cast axial split dry-type transformer, including an iron core, a coil assembly and a cooling fan, wherein the coil assembly has a low-voltage coil and a high-voltage coil, and two sections of the low-voltage coil are wound in the vertical direction and on the outer periphery of the iron core, and the two sections of the low-voltage coil are integrally cast with a low-voltage casting body;

[0008] The core is wound with two or more even-numbered high-voltage coils in the vertical direction and around the outer periphery of the low-voltage coil. The high-voltage coils are divided into upper and lower parts on an equal basis. The winding directions of the upper and lower high-voltage coils are opposite and they are integrally cast with a high-voltage casting body.

[0009] The cooling fan is positioned below the low-pressure and high-pressure casting bodies and blows air upwards from below each casting body to dissipate heat.

[0010] Furthermore, the spacing between the two low-voltage coil sections is 20-30mm.

[0011] Furthermore, the high-voltage coils wound vertically on the core are arranged at equal intervals, with a spacing of 10-20mm.

[0012] Furthermore, the terminal panel on the same side of the high-pressure casting body is provided with a starting terminal, a tail terminal and a tap terminal. The left and right rows of tap terminals are staggered vertically. The starting terminal and the tail terminal are respectively located above and below the tap terminals and on the vertical center line between the left and right rows of tap terminals.

[0013] Furthermore, the inclination angle of the center connection line between the two rows of tap terminals is 28-35°, and the distance between the center connection lines between the two rows of tap terminals is 40-50mm.

[0014] Furthermore, the coil assembly has three phases (A, B, and C) arranged in parallel on the transformer base. The starting and ending terminals of the high-voltage casting body of the three-phase coil assembly are connected in parallel to each other through lead wires, and the end of the lead wire connected to each terminal is bent at 90-120°.

[0015] Furthermore, an upper clamping assembly and a lower clamping assembly are respectively provided at the upper and lower ends of the coil assembly, and the coil assembly is mounted on the transformer base through the lower clamping assembly; the transformer base is composed of two parallel bottom beams, and several cooling fans are provided on the two bottom beams.

[0016] Furthermore, the two ends of the front and rear clamping plates of the upper clamping assembly and the lower clamping assembly are locked together by the first locking rod.

[0017] Furthermore, the upper clamping assembly and the lower clamping assembly have a plurality of locking lugs in the middle of the front and rear clamping plates. The locking lugs are extended from the sides of the front and rear clamping plates and are locked together by the second locking rod.

[0018] Furthermore, several layers of insulating cylinders of the same or different thicknesses are provided between the low-voltage coil and the iron core and the high-voltage coil.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows: by integrating the low-voltage coil and the high-voltage coil into a single casting, the problem of traditional use of spacers to support the upper and lower coil sections and thus affecting heat dissipation is solved. This simplifies the winding and insulation process, reduces manufacturing costs, and allows the cooling fan below to blow directly into the unobstructed axial ventilation channel without spacers. The airflow evenly covers the high and low voltage coils, improving heat dissipation efficiency by more than 30%. The upper and lower high-voltage coils are wound in opposite directions to cancel leakage flux, improve electromagnetic balance, and enhance mechanical strength and resistance to sudden short circuits. Attached Figure Description

[0020] Figure 1 This is a three-dimensional schematic diagram of a dry-type transformer in a preferred embodiment of the present invention;

[0021] Figure 2 This is a front view of the dry-type transformer in a preferred embodiment of the present invention;

[0022] Figure 3 for Figure 2 Cross-sectional view after cutting along the BB direction;

[0023] Figure 4 This is a cross-sectional view of a single-phase coil winding in a preferred embodiment of the present invention.

[0024] In the picture:

[0025] 10. Iron heart;

[0026] 20. Coil assembly; 201. Low-voltage coil; 202. High-voltage coil; 203. Low-voltage casting body; 204. High-voltage casting body; 2041. Terminal panel; 2042. Starting terminal; 2043. Ending terminal; 2044. Tap terminal; 2045. Lead wire; 205. Insulating cylinder;

[0027] 30. Cooling fan;

[0028] 40. Transformer base; 401. Bottom beam;

[0029] 50. Upper clamping assembly; 501. Locking lug; 502. Front and rear clamping plates; 51. Lower clamping assembly; 52. First locking rod; 53. Second locking rod. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0031] like Figure 1-4 As shown, an integrated cast axially split dry-type transformer has been widely used in wind power generation, photovoltaic power generation, and energy storage industries. This integrated cast axially split dry-type transformer includes a core 10, an ABC three-phase coil assembly 20, a cooling fan 30, and a transformer base 40. The core 10 uses stacked silicon steel sheets to form a closed magnetic circuit. Two low-voltage coils 201 are wound sequentially along its vertical direction and outer circumference. The two low-voltage coils 201 are wound continuously. After winding, the entire assembly is impregnated with epoxy resin and vacuum-cast to form an integrated low-voltage cast body 203. There are no spacers separating the cast body.

[0032] The high-voltage coil 202 is then wound in segments on the outside of the low-voltage casting body 203. The total number of segments of the high-voltage coil 202 is even (e.g., 4 segments). The upper and lower parts each account for half of the number of segments, and the winding directions of the upper and lower parts are opposite (e.g., the upper part is wound clockwise and the lower part is wound counterclockwise). After the winding is completed, the whole body is cast with epoxy resin to form the high-voltage casting body 204.

[0033] The cooling fan 30 is mounted on the transformer base 40 and is located directly below the low-voltage casting body 203 and the high-voltage casting body 204. The fan axis is perpendicular to the ground and blows air upward through the axial ventilation channel between the coils.

[0034] Therefore, by integrating the low-voltage coil 201 and the high-voltage coil 202 into a single casting, the problem of traditionally using spacers to support the upper and lower coil sections, which affects heat dissipation, is solved. This simplifies the winding and insulation processes, reduces manufacturing costs, and allows the cooling fan 30 to blow directly through an unobstructed axial ventilation channel without spacers. The airflow evenly covers the high and low voltage coils 201, improving heat dissipation efficiency by more than 30%. The upper and lower high-voltage coils 202 are wound in opposite directions to cancel leakage flux, improve electromagnetic balance, and enhance mechanical strength.

[0035] The two low-voltage coil sections 201 are spaced 25mm apart (ranging from 20-30mm) in the vertical direction of the core 10. They are precisely positioned using a winding mold, and during casting, epoxy resin is filled into the spaced area to form a continuous insulation layer, ensuring an inter-section insulation strength ≥5kV / mm. Therefore, by arranging the two low-voltage coil sections 201 with a 20-30mm spacing, the reliability of the inter-section insulation is guaranteed while avoiding volume redundancy caused by excessive spacing, resulting in a more compact overall structure and a 15% increase in space utilization.

[0036] By winding the high-voltage coil 202 into four vertical segments on the iron core 10, with a spacing d2 of 15mm between adjacent segments (ranging from 20-30mm), and using an equidistant winding mold to control the segment spacing, epoxy resin is filled into the spacing area during casting to form a continuous insulation layer, ensuring the inter-segment insulation strength. Therefore, the equidistant segmented arrangement of the high-voltage coil 202 ensures uniform heat dissipation and avoids localized overheating. Simultaneously, the equidistant structure enhances the coil's overall resistance to short-circuit electrodynamic forces, improving mechanical stability by 20%.

[0037] The high-pressure casting body 204 provided in this embodiment has a terminal panel 2041 on the left or right side, and three sets of terminals are provided on the terminal panel 2041: a starting terminal 2042, a ending terminal 2043, and a tap terminal 2044. The tap terminals 2044 are divided into two rows of terminals, arranged in a staggered manner, with the left row of terminals positioned 20mm lower than the right row. The tilt angle α between the center lines of the two rows of terminals is 32° (the tilt angle range is 28-35°). This 30° tilt angle optimizes the electric field distribution between the terminals, reducing the risk of partial discharge. The center-to-center distance between the left and right rows of tap terminals 2044 is 45mm (the range is 40-50mm). This 45mm center-to-center distance ensures sufficient installation space for operating tools (such as wrenches), improving maintenance convenience by 40%. Simultaneously, the creepage distance between adjacent terminals is ≥50mm, ensuring sufficient electrical clearance. Therefore… By staggering the layout of the left and right rows of tap terminals 2044, the risk of electric arc creepage between adjacent terminals is avoided, and the tilted design saves horizontal space on the panel.

[0038] Furthermore, the starting terminal 2042 and the ending terminal 2043 are respectively positioned above and below the tap terminal 2044, with the starting terminal 2042 and the ending terminal 2043 located on the vertical center line of the two rows of tap terminals 2044. Therefore, by arranging the starting terminal 2042 and the ending terminal 2043 corresponding to the vertical center line of the tap terminal 2044, the lead length is shortened, improving wiring efficiency by 25%, while ensuring that the creepage distance between each terminal is the same.

[0039] The ABC three-phase coil assemblies 20 are arranged in parallel on the transformer base 40. The U1, V1, and W1 starting terminals 2042 and ending terminals 2043 of the ABC three-phase high-voltage cast bodies 204 are connected in parallel via copper busbars or copper strips as leads 2045. The connection ends of each terminal lead 2045 adopt a 105° bend design (bending range 90-120°), with a bending radius R = 30mm, and the bend is covered with heat-shrinkable insulating tubing. Therefore, through the wiring design of each lead and the 90-120° bend at the connection end, the cross interference of the three-phase leads is reduced, and the eddy current loss is reduced by 15%; the parallel connection balances the three-phase load current, and the temperature rise is reduced by 8-10℃.

[0040] The coil assembly 20 is fixed by the upper clamping assembly 50 (Q235 steel plate) and the lower clamping assembly 51 (Q345 steel plate), with the lower clamping assembly 51 mounted on the transformer base 40. The transformer base 40 consists of two parallel bottom beams 401 (channel steel 200×75×9mm), allowing the lower clamping assembly 51 to be mounted on the two parallel bottom beams 401 using M16 bolts. Each bottom beam 401 has at least one set of high-voltage wiring insulators on its front side. The double bottom beam 401 structure increases vibration resistance by 3 times, distributes the coil weight, and improves the base's deformation resistance by 30%, solving the problem of poor stability in previous structures. Furthermore, the two bottom beams 401 are spaced a certain distance apart, and each bottom beam 401 is equipped with several axial flow fans that blow heat upwards onto the coil. The parallel arrangement of multiple fans forms a uniform air curtain, increasing the heat dissipation coverage area by 50%.

[0041] To further improve the installation stability of the transformer, Φ20mm through holes are provided at both ends of the front and rear clamping plates 502 of the upper clamping assembly 50 and the lower clamping assembly 51. Four M18 first locking rods 52 (500mm in length) are passed through and locked, with a locking torque of 80N·m. If necessary, disc springs can be installed between the clamping plates and the locking rods. By locking the four corners, the flatness error of the clamping assembly is ≤0.1mm / m. Locking at both ends ensures that the clamping assembly is tightly fitted to the coil, improving the vibration resistance by 40%, solving the problem of clamp deformation, and preventing cracking of the casting.

[0042] Two or more sets of locking lugs 501 (12mm thick) are welded to the middle of the front and rear clamping plates 502 of each clamping assembly. Each locking lug 501 has a Φ14mm hole and is laterally locked by two M12 second locking rods 53. A preload of 50 N·m is applied after the second locking rods 53 pass through the lugs. Triangular reinforcing ribs are welded between the locking lugs 501 and the clamping assembly. An insulating sleeve is installed in the middle of the second locking rods 53. The locking lugs 501 are spaced 200mm apart. Thus, by using the second locking rods 53 in the middle of the clamping assembly for locking, the axial displacement of the coil is reduced to <0.05mm, and the uniformity of the coil axial clamping force is improved by 25%, thereby solving the problem of coil axial loosening. Furthermore, the middle locking lugs 501 reduce the bending deformation of the clamping assembly, and the reinforcing ribs enhance the shear strength of the lugs, preventing the locking rods from loosening.

[0043] In this embodiment, several layers of insulating tubes 205 of the same or different thicknesses are provided between the low-voltage coil 201 and the core 10, and between the high-voltage coil 202. For example, three layers of 1mm thick Nomex insulating paper tubes are provided between the low-voltage coil 201 and the core 10, and two layers of 2mm thick epoxy glass cloth tubes are provided between the high-voltage coil 202 and the low-voltage coil 201. Silicone grease is applied between the layers to enhance adhesion. By using insulating tubes 205 of different thicknesses to adapt to different voltage gradients, the insulation withstand voltage level is improved to 35kV / mm; the silicone grease filling eliminates air gaps, and the partial discharge quantity is <5pC.

[0044] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. An integrated cast axial split dry-type transformer characterized by, The application relates to a transformer, which comprises an iron core, a coil assembly and a cooling fan, the coil assembly has low-voltage coils and high-voltage coils, two sections of the low-voltage coils are wound on the vertical direction and the outer periphery of the iron core, and the two sections of the low-voltage coils are integrally cast with a low-voltage casting body. The vertical direction of the iron core and the outer periphery of the low-voltage coils are wound with two or more even sections of the high-voltage coils, the high-voltage coils of the sections are averagely divided into upper and lower parts, the winding directions of the high-voltage coils of the upper and lower parts are opposite, and the high-voltage coils are integrally cast with a high-voltage casting body. The cooling fan is arranged below the low-voltage casting body and the high-voltage casting body and sends air upward from below the casting bodies to dissipate heat.

2. The integrated cast axial split dry-type transformer of claim 1, wherein, The interval between the two sections of the low-voltage coils is 20-30 mm.

3. The one-piece cast axial split dry-type transformer of claim 1, wherein, The intervals of the sections of the high-voltage coils wound on the vertical direction of the iron core are equidistantly arranged, and the interval is 10-20 mm.

4. The one-piece cast axial split dry-type transformer of claim 1, wherein, A starting connection terminal, an ending connection terminal and a tapping connection terminal are arranged on the same side terminal panel of the high-voltage casting body, the left and right rows of the tapping connection terminals are arranged in an up-down staggered mode, and the starting connection terminal and the ending connection terminal are respectively arranged above and below the tapping connection terminals and on the vertical center line between the left and right rows of the tapping connection terminals.

5. The integrated cast axial split dry-type transformer of claim 4, wherein, The inclination angle of the center connecting line between the left and right rows of the tapping connection terminals is 28-35 DEG, and the distance between the center connecting lines of the left and right rows of the tapping connection terminals is 40-50 mm.

6. The one-piece cast axial split dry-type transformer of claim 1, wherein, The coil assembly is arranged in parallel with ABC three-phase on a transformer base, the starting connection terminal and the ending connection terminal of the high-voltage casting body of the ABC three-phase coil assembly are connected in parallel with each other through lead-out wires, and one end of the lead-out wire connected with each connection terminal is bent by 90-120 DEG.

7. The integrated cast axial split dry-type transformer of claim 6, wherein, Upper and lower ends of the coil assembly are respectively provided with upper and lower clamping piece assemblies, and the coil assembly is installed on the transformer base through the lower clamping piece assembly; the transformer base is composed of two parallel arranged bottom beams, and a plurality of the cooling fans are arranged on the two bottom beams.

8. The integrated cast axial split dry-type transformer of claim 7, wherein, The two ends of the front and rear clamping plates of the upper and lower clamping piece assemblies are locked and connected with each other through first locking rods.

9. The integrated cast axial split dry-type transformer of claim 7, wherein, The middle parts of the front and rear clamping plates of the upper and lower clamping piece assemblies are provided with a plurality of locking ear plates which are led out from the side parts of the front and rear clamping plates and locked and connected with each other through second locking rods.

10. The one-piece cast axial split dry-type transformer of claim 1, wherein, A plurality of layers of insulation cylinders with the same thickness or different thicknesses are arranged between the low-voltage coils and the iron core and the high-voltage coils.

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