Double-panel on-load voltage regulation dry-type transformer

Abstract

The utility model discloses a double-panel on-load voltage regulation dry-type transformer which comprises an iron core, a coil assembly and an on-load switch, the coil assembly is provided with a low-voltage coil and a high-voltage coil, the low-voltage coil is wound on the periphery of the iron core, and a low-voltage pouring body is poured on the low-voltage coil; the high-voltage coil is wound on the periphery of the low-voltage coil, a high-voltage pouring body is poured on the high-voltage coil, the high-voltage pouring body is provided with a first terminal panel and a second terminal panel, and the first terminal panel and the second terminal panel are correspondingly arranged on the opposite side faces of the high-voltage pouring body; the first terminal panel is provided with a starting wiring terminal and a tail wiring terminal, the second terminal panel is provided with a tapping wiring terminal, and the second terminal panel is electrically connected with the on-load switch through a lead-out wire of the tapping wiring terminal. Therefore, the creepage distance between the terminals and the creepage distance between the terminals and the outgoing line of the on-load switch are increased, and according to the double-panel design of the high-voltage pouring body, the material cost and the size of the transformer are reduced.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to a double-sided on-load tap-changing 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: the core, coils, and insulation materials. The windings are divided into high-voltage coils and low-voltage coils and are wound around the core. 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 arcing, and also have fire-resistant properties.

[0004] For example, Chinese invention patent CN105336479A, entitled "A Maintenance-Free Three-Phase High-Efficiency Energy-Saving Dry-Type Transformer for Electric Furnaces," includes a transformer body and an on-load tap changer mounted on a base. The transformer body and the on-load tap changer are connected via a high-voltage tap cable. The transformer body includes three vertically evenly distributed iron cores, with low-voltage and high-voltage coils wound around the outer circumference of the three iron cores respectively. A connecting rod is located to the right of the high-voltage coil, along with a high-voltage support and a low-voltage support located above the iron cores, and a low-voltage neutral point copper busbar located between the low-voltage and high-voltage supports. The connecting rod connects the end terminals of the three high-voltage coils, forming a triangular connection between the three phases of the high-voltage coils in the circuit, providing users with high-voltage terminals supported by high-voltage supports.

[0005] However, the existing technology still has the following drawbacks: The high-voltage casting body of the existing dry-type transformer usually adopts a single-sided terminal panel. Therefore, the starting lead terminal, the ending lead terminal, and the tap changer lead terminal for voltage regulation are all arranged on the same terminal panel, which leads to excessively close creepage distances between the lead terminals. This is especially true when the voltage level is high and when an on-load switch is connected to the tap changer, which can easily cause electrical hazards and fail to meet electrical strength requirements. In addition, in the past, in order to increase the creepage distance between the terminals, the height and width of the casting body could only be increased to increase the spacing between the terminals, but this would lead to higher material costs. Utility Model Content

[0006] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a double-sided on-load tap-changing dry-type transformer.

[0007] The purpose of this utility model is achieved by the following technical solution: a double-sided on-load tap-changing dry-type transformer, including an iron core, a coil assembly and an on-load switch, wherein the coil assembly has a low-voltage coil and a high-voltage coil, and the low-voltage coil is wound around the outer periphery of the iron core and cast with a low-voltage casting body.

[0008] The high-voltage coil is wound around the outer periphery of the low-voltage coil and is cast with a high-voltage casting body. The high-voltage casting body has a first terminal panel and a second terminal panel, which are respectively disposed on opposite sides of the high-voltage casting body.

[0009] The first terminal panel is provided with a start terminal and a end terminal, and the second terminal panel is provided with a tap terminal, through which the lead wire is electrically connected to the on-load switch.

[0010] Furthermore, the left and right rows of terminals of the tap connection terminal are staggered vertically; the tilt angle of the center line connecting the left and right rows of tap connection terminals is 28-35°, and the distance between the center lines connecting the left and right rows of tap connection terminals is 40-50mm.

[0011] Furthermore, the center-to-center distance between the starting and ending terminals on the first terminal panel is 220-250mm.

[0012] Furthermore, the coil assembly has three phases, A, B, and C. The starting terminal of the high-voltage casting body of phase A and the ending terminal of the high-voltage casting body of phase C are connected through the AC phase lead wire, and the AC phase lead wire is arranged in front of the transformer base through several high-voltage wiring insulators.

[0013] Furthermore, the tail terminal of the high-pressure casting body of phase A is connected to the starting terminal of the high-pressure casting body of phase B through the AB phase lead wire, and the tail terminal of the high-pressure casting body of phase B is connected to the starting terminal of the high-pressure casting body of phase C through the BC phase lead wire. Moreover, one end of the AC phase lead wire, AB phase lead wire, and BC phase lead wire connected to each terminal is bent at 90-120°.

[0014] Furthermore, the low-voltage lead insulator of the low-voltage coil is located on the side where the coil assembly is connected to the on-load switch, and the high-voltage lead insulator of the high-voltage coil is located on the side of the coil assembly away from the on-load switch.

[0015] Furthermore, the upper and lower ends of the coil assembly are respectively provided with an upper clamping assembly and a lower clamping assembly. 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 both bottom beams are provided with high-voltage wiring insulators for stable arrangement of lead wires.

[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, the low-pressure casting body and the high-pressure casting body are integrally cast on the low-pressure coil and the high-pressure coil, respectively, and the iron core is vertically wound with two sections of the low-pressure coil and several sections of the high-pressure coil arranged at equal intervals.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows: By designing a double-sided panel for the high-voltage casting body, the starting and ending terminals are arranged on the same side panel, while the tap terminals are arranged on the other side panel, thereby achieving separate arrangement of high-voltage terminals. The double-sided panel design increases the distance between the starting and ending terminals from the traditional 150mm to over 235mm (compliant with IEC60076-11 standard), increasing the creepage distance by over 60%, solving the problem of insufficient terminal spacing on a single panel, especially addressing the previous problem of excessively short creepage distances between the starting and ending terminals and the tap terminals and on-load switches, thus avoiding electrical hazards. In addition, the embodiments of this application, through the double-sided panel design of the high-voltage casting body, eliminate the need to increase the height of the casting body to increase the spacing between the terminals as in the past, significantly reducing material costs and size. Compared with the traditional solution, the material cost is reduced by 22%, and the volume of the casting body is reduced by 18%. Attached Figure Description

[0020] Figure 1 This is a plan view showing the connection between the dry-type transformer and the on-load switch in a preferred embodiment of the present invention.

[0021] Figure 2 This is a three-dimensional schematic diagram of a dry-type transformer in a preferred embodiment of the present invention;

[0022] Figure 3 This is a perspective view of the high-pressure casting body in a preferred embodiment of the present invention;

[0023] Figure 4This is a schematic diagram showing one side of the high-pressure casting body with the starting and ending terminals in a preferred embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram showing one side of the tap connection terminal of the high-pressure casting body in a preferred embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram showing a partial cross-section of the high-voltage coil in a preferred embodiment of the present invention.

[0026] In the picture:

[0027] 10. Iron heart;

[0028] 20. Coil assembly; 201. Low-voltage coil; 202. High-voltage coil; 203. Low-voltage casting body; 204. High-voltage casting body; 2041. First terminal panel; 20411. Starting terminal; 20412. Ending terminal; 2042. Second terminal panel; 2421. Tap terminal;

[0029] 30. On-load switch;

[0030] 40. AC phase lead-out line; 41. AB phase lead-out line; 42. BC phase lead-out line

[0031] 50. High-voltage wiring insulators;

[0032] 60. Transformer base; 601. Bottom beam;

[0033] 70. Upper clamping assembly; 701. Front and rear clamping plates; 702. Locking lugs; 71. Lower clamping assembly; 72. First locking rod; 73. Second locking rod;

[0034] 80. Low-voltage lead-out insulator; 81. High-voltage lead-out insulator;

[0035] 90. Insulating cylinder. Detailed Implementation

[0036] The present invention will now be further described in conjunction with 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.

[0037] like Figure 1-6As shown, a double-sided on-load tap-changing dry-type transformer has been widely used in wind power generation, photovoltaic power generation, and energy storage industries. This double-sided on-load tap-changing dry-type transformer includes a core 10, an ABC three-phase coil assembly 20, and an on-load switch 30. The coil assembly 20 has a low-voltage coil 201 and a high-voltage coil 202. Several layers of insulating cylinders 90 are sleeved between the low-voltage coil 201 and the core 10, and between the low-voltage coil 201 and the high-voltage coil 202. The low-voltage coil 201 is wound with epoxy resin around the outer periphery of the core 10 and integrally cast to form a low-voltage casting body 203. The high-voltage coil 202 is wound around the outside of the low-voltage coil 201 and integrally cast in a vacuum to form a high-voltage casting body 204. The integrally cast low-voltage coil 201 and high-voltage coil 202 have better overall structural strength, are easier to process, and facilitate heat dissipation by the bottom cooling fan.

[0038] The high-pressure casting body 204 is provided with a first terminal panel 2041 (front) and a second terminal panel 2042 (back). The first terminal panel 2041 is provided with a starting terminal 20411 and a ending terminal 20412. The second terminal panel 2042 is provided with a set of tap terminals 2421. The tap terminals are connected to the on-load switch 30 through copper busbars or cables.

[0039] Therefore, by designing a double-sided panel for the high-pressure casting body 204, the starting terminal 20411 and the ending terminal 20412 are arranged on the same side panel, while the tap terminal 2421 is arranged on the other side panel, thus achieving separate arrangement of high-pressure terminals. The double-sided panel design increases the terminal spacing h1 between the starting terminal 20411 and the ending terminal 20412 from the traditional 150mm to over 235mm (compliant with IEC60076-11 standard), improving the creepage distance by over 60% and solving the problem of single-sided... The problem of insufficient spacing between board terminals is addressed, particularly the issue of excessively short creepage distance between the lead wires of the starting terminal 20411, the ending terminal 20412, the tap terminal 2421, and the on-load switch 30, thus avoiding potential electrical hazards. Furthermore, this embodiment of the application, through the double-sided design of the high-voltage casting body 204, eliminates the need to increase the height of the casting body to widen the spacing between terminals, as was previously required, significantly reducing material costs and size. Compared to traditional solutions, material costs are reduced by 22%, and the volume of the casting body is reduced by 18%.

[0040] Preferably, the low-voltage coil 201 is wound in two sections vertically in the core 10, with a section spacing of approximately 50mm, and each section has more than 12 layers. The high-voltage coil 202 is wound in several sections vertically in the core 10, at least three sections wound at equal intervals, with 3mm epoxy resin partitions between the sections. The casting body adopts a vacuum integrated casting process, with a casting temperature of 85℃ and a curing time of 8 hours. By segmenting the winding of the low-voltage coil 201 and the high-voltage coil 202, the temperature rise is reduced by 25K, the cracking rate of the casting body is reduced by 90%, and the problem of poor heat dissipation is further solved.

[0041] The longitudinal center distance h2 between the starting terminal 20411 and the ending terminal 20412 on the first terminal panel 2041 is 235mm (range 220-250mm). Figure 4 As shown. If necessary, Φ12mm copper bolts with silver plating are used for the terminals, and 20mm wide insulating bosses are provided between the terminals. Therefore, by optimizing the spacing between the starting terminal 20411 and the ending terminal 20412, the power frequency withstand voltage is increased from 28kV to 42kV, solving the problem of insufficient insulation between the starting terminal 20411 and the ending terminal 20412.

[0042] The tap changer terminals 2421 are arranged in two staggered rows on the second terminal panel 2042. Specifically, the center lines of the left row and the right row form a 30° angle α (range 28-35°), and the center distance between the two rows of terminals is 45mm (range 40-50mm). Figure 5 As shown, a stepped terminal layout is adopted, with the left row of terminals being 15mm higher than the right row. If necessary, the terminal spacing can be separated by insulating partitions. Therefore, by staggering the layout of the split terminal groups, the effective insulation distance at the same row spacing is increased by 35%, meeting the 35kV insulation requirements and resolving the risk of discharge between taps.

[0043] The starting terminal 20411 of the A-phase high-voltage cast body 204 and the ending terminal 20412 of the C-phase are connected via the AC-phase lead-out line 40. The AC-phase lead-out line 40 uses double-layer insulated copper busbars or copper wires and is fixed to the front side of the transformer base 60 via at least two high-voltage wiring insulators 50. The insulators are made of ceramic material, with a spacing of more than 120mm, and a silicone rubber buffer pad is placed between the copper busbar and the high-voltage wiring insulator 50. Therefore, by setting the high-voltage wiring insulators 50 on the front side of the transformer base 60, the routing and positioning of the AC-phase lead-out line 40 connected across phases are facilitated, which can improve the routing stability and ensure the creepage distance; in addition, the external AC-phase wiring reduces the interphase coupling capacitance by 40%, reduces the partial discharge, and solves the interphase interference problem.

[0044] Furthermore, the wiring relationship between the high-voltage casting bodies 204 of phases A and B is as follows: phase A lead 41 connects the tail terminal 20412 of phase A to the starting terminal 20411 of phase B, and phase B lead 42 connects the tail terminal 20412 of phase B to the starting terminal 20411 of phase C. Moreover, the connection ends of each lead 40 of phase AC, phase AB, and phase BC adopt a 105° bend design (bending range 90-120°), with a bending radius R = 30mm, and the bend is covered with a heat-shrinkable insulating sleeve. Therefore, through the wiring design of each lead and the bending design of the connection ends, the mechanical stress is reduced by 55%, the temperature rise at the connection point is reduced by 20K, and the problem of stress concentration at the connection is solved.

[0045] Further description is given regarding the lead-out insulators at the low-voltage and high-voltage ends. For example, the low-voltage lead-out insulator 80 is positioned on the right side of the coil assembly 20 (on-load tap changer 30 side), employing three sets of Φ80mm epoxy resin insulators; while the high-voltage lead-out insulator 81 is positioned on the left side of the coil assembly 20, employing four sets of Φ100mm ceramic insulators. While ensuring ease of wiring, the spacing between the high-voltage and low-voltage insulators is ≥300mm. This spatial isolation reduces the induced voltage to below 0.5kV, resolving the high- and low-voltage interference problem.

[0046] The coil assembly 20 is fixed by the upper clamping assembly 70 (Q235 steel plate) and the lower clamping assembly 71 (Q345 steel plate). The lower clamping assembly 71 is mounted on the transformer base 60. The transformer base 60 is composed of two parallel bottom beams 601 (channel steel 200×75×9mm), so the lower clamping assembly 71 can be installed on the two parallel bottom beams 601 by M16 bolts. Each bottom beam 601 has at least one set of high-voltage wiring insulators 50 on its front side. The double bottom beam 601 structure improves the vibration resistance by 3 times, solving the problem of poor structural stability in the past.

[0047] To further improve the installation stability of the transformer, Φ20mm through holes are provided at both ends of the front and rear clamping plates 701 of the upper clamping assembly 70 and the lower clamping assembly 71. Four M18 first locking rods 72 (500mm in length) are passed through and locked, with a locking torque of 120N·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, thus solving the problem of clamp deformation.

[0048] Two or more sets of locking lugs 702 (12mm thick) are welded to the middle of the front and rear clamping plates 701 of each clamping assembly. Each locking lug 702 has a Φ14mm hole and is laterally locked by two M12 second locking rods 73. An insulating sleeve is installed in the middle of each second locking rod 73, and the locking lugs 702 are spaced 200mm apart. In this way, by using the second locking rods 73 to lock the clamping assembly in the middle, the axial displacement of the coil is kept <0.05mm, thus solving the problem of axial loosening of the coil.

[0049] 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. A double-sided panel type dry-type transformer with on-load tap changer, characterized in that, The transformer comprises a core, a coil assembly and a load switch, the coil assembly has a low-voltage coil and a high-voltage coil, the low-voltage coil is wound around the outer periphery of the core and is cast with a low-voltage casting body; The high-voltage coil is wound around the outer periphery of the low-voltage coil and is cast with a high-voltage casting body, the high-voltage casting body has a first terminal panel and a second terminal panel, the first terminal panel and the second terminal panel are arranged on opposite sides of the high-voltage casting body; The first terminal panel is provided with a start terminal and an end terminal, and the second terminal panel is provided with a tapping terminal, and the tapping terminal is electrically connected to the load switch.

2. The double-sided panel type load regulation dry-type transformer according to claim 1, wherein The left and right rows of terminals of the tapping terminal are arranged in an up-down staggered manner; the center connecting line between the left and right rows of the tapping terminal has an inclination angle of 28-35°, and the center connecting line distance between the left and right rows of the tapping terminal is 40-50mm.

3. The double-sided panel type load regulation dry-type transformer according to claim 1, wherein The center connecting line distance between the start terminal and the end terminal on the first terminal panel is 220-250mm.

4. The double-sided panel type load regulation dry-type transformer according to claim 1, wherein The start terminal of the high-voltage casting body of the A phase and the end terminal of the high-voltage casting body of the C phase are connected by an AC phase lead, and the AC phase lead is arranged in front of the transformer base through a plurality of high-voltage wiring insulators.

5. The double-sided panel coreless dry-type transformer of claim 4, wherein, The end terminal of the high-voltage casting body of the A phase and the start terminal of the high-voltage casting body of the B phase are connected by an AB phase lead, and the end terminal of the high-voltage casting body of the B phase and the start terminal of the high-voltage casting body of the C phase are connected by a BC phase lead, and one end of each of the AC phase lead, the AB phase lead and the BC phase lead connected to the terminal is bent by 90-120°.

6. The double-sided panel coreless dry-type transformer of claim 1, wherein, The low-voltage lead insulator of the low-voltage coil is arranged on the side of the coil assembly connected to the load switch, and the high-voltage lead insulator of the high-voltage coil is arranged on the side of the coil assembly away from the load switch.

7. The double-sided panel coreless dry-type transformer of claim 1, wherein, The upper and lower ends of the coil assembly are respectively provided with an upper clamp assembly and a lower clamp assembly, the coil assembly is installed on the transformer base through the lower clamp assembly, the transformer base is composed of two parallel bottom beams, and high-voltage wiring insulators for stabilizing the arrangement of the lead are arranged on the two bottom beams.

8. The double-sided panel coreless dry-type transformer of claim 7, wherein, The two ends of the front and rear clamping plates of the upper clamp assembly and the lower clamp assembly are locked and connected to each other by a first locking rod.

9. The double-sided panel coreless dry-type transformer of claim 7, wherein, The middle part of the front and rear clamping plates of the upper clamp assembly and the lower clamp assembly is provided with a plurality of locking ear plates, the locking ear plates are led out from the side of the front and rear clamping plates and are locked and connected to each other by a second locking rod.

10. The double-sided panel coreless dry-type transformer of claim 1, wherein, The low-voltage casting body and the high-voltage casting body are integrally cast on the low-voltage coil and the high-voltage coil respectively, and the core is vertically wound with two low-voltage coils and a plurality of high-voltage coils arranged at equal intervals.

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