35kV novel dry-type grounding transformer

Abstract

The utility model discloses a 35kV novel dry-type grounding transformer which comprises an iron core, coil assemblies and a transformer base, each phase of coil assembly is provided with an inner high-voltage coil and an outer high-voltage coil, the inner high-voltage coils are wound on the periphery of the iron core, and a low-voltage pouring body is integrally poured on the inner high-voltage coils. The outer high-voltage coil is wound on the periphery of the inner high-voltage coil, and a high-voltage pouring body is integrally poured on the outer high-voltage coil; an inner starting leading-out wire and an inner tail leading-out wire are correspondingly led out from the upper end and the lower end of the inner high-voltage coil respectively, and the inner starting leading-out wire is bent outwards from the top of the coil assembly and extends upwards to be connected with an inner high-voltage leading-out wire insulator. The inner tail leading-out wire is bent outwards from the bottom of the coil assembly and is connected with the outer tail leading-out wire of the high-voltage pouring body along the arrangement direction of a high-voltage wiring insulator on the transformer base, and the outer starting leading-out wires of the three phases of coil assemblies are connected with one another and extend upwards to be connected with an outer high-voltage leading-out wire insulator. Therefore, the electrical safety distance is increased, the wiring is more stable, safe and reliable, and the cost is low.

Description

TECHNICAL FIELD

[0001] The utility model relates to transformer technical field especially relates to a 35kV novel dry type grounding transformer. BACKGROUND

[0002] The transformer is the core component of the power transformation part in the power system, and the transformer can be divided into a dry type transformer and an oil immersed transformer according to the cooling mode, wherein the dry type transformer is a kind of transformer without the iron core and coil immersed in insulating liquid, has the advantages of low consumption, high efficiency, moisture-proof, flame-retardant, pollution-free and convenient maintenance, and is widely applied in the fields of wind power generation, photovoltaic power generation and energy storage.

[0003] The dry type transformer is usually composed of iron core, coil and insulating material, wherein the insulating material is mostly poured into a pouring body by using inorganic material such as epoxy resin, for wrapping the coil and iron core to insulate current and prevent electric arc, and also has fireproof performance;And the inner coil and outer coil of the 35kV dry type grounding transformer are high-voltage coils, and the inner high-voltage coil is wound around the iron core from outside to inside, and the outer high-voltage coil is wound around the outer periphery of the inner high-voltage coil;The coil lead of the dry type grounding transformer is usually connected by using zigzag connection (ZN connection), and the upper half and the lower half of each phase are wound in the same coil, and then the insulating material is poured.

[0004] However, the existing technology still has the following defects: the lead of the upper half coil of the existing dry type grounding transformer needs to span from the end of the lower half coil, and the electrical safety distance is not easy to guarantee, and the lead connecting wire is realized by welding, so that the high temperature generated by welding is easy to damage the turn insulation, and further cause safety hazard. UTILITY MODEL CONTENTS

[0005] In order to overcome the defects of the prior art, the purpose of the utility model is to provide a 35kV novel dry type grounding transformer.

[0006] The utility model discloses a 35kV novel dry type grounding transformer, including the iron core, coil assembly and transformer base, the coil assembly has three phases, and each phase coil assembly is provided with inner high-voltage coil and outer high-voltage coil respectively, the inner high-voltage coil is wound on the outer periphery of the iron core and integrally poured with low-pressure pouring body, and the outer high-voltage coil is wound on the outer periphery of the inner high-voltage coil and integrally poured with high-pressure pouring body;

[0007] The transformer base is provided with a plurality of high-voltage wiring insulators corresponding to each phase coil assembly;

[0008] The upper and lower ends of the inner high-voltage coil correspond to the inner head lead-out wire and the inner tail lead-out wire, respectively, the inner head lead-out wire is bent outward from the top of the coil assembly and extends upward to connect the inner high-voltage lead-out wire insulator, and the inner tail lead-out wire is bent outward from the bottom of the coil assembly and connected to the outer tail lead-out wire of the high-voltage pouring body along the setting direction of the high-voltage wiring insulator, and the outer head lead-out wires of the three-phase coil assembly are connected to each other and extend upward to connect the outer high-voltage lead-out wire insulator.

[0009] Further, the inner high-voltage lead-out wire insulator and the outer high-voltage lead-out wire insulator are arranged on the same side of the coil assembly.

[0010] Further, the coil assembly is arranged side by side on the transformer base with ABC three-phase; the upper and lower ends of the coil assembly are respectively provided with upper and lower clamping assemblies, and the coil assembly is installed on the transformer base through the lower clamping assembly.

[0011] Further, the transformer base is composed of two parallel bottom beams, and the two bottom beams are connected by two parallel connecting plates, and two high-voltage wiring insulators are arranged along the direction of the two connecting plates and corresponding to each phase coil assembly.

[0012] The inner tail lead-out wire of the A-phase coil assembly is connected to the outer tail lead-out wire of the C-phase coil assembly along the setting direction of the corresponding two high-voltage wiring insulators of the A-phase and the distal high-voltage wiring insulator of the B-phase;

[0013] The inner tail lead-out wire of the B-phase coil assembly is connected to the outer tail lead-out wire of the A-phase coil assembly along the setting direction of the proximal high-voltage wiring insulator corresponding to the B-phase;

[0014] The inner tail lead-out wire of the C-phase coil assembly is connected to the outer tail lead-out wire of the B-phase coil assembly along the setting direction of the proximal high-voltage wiring insulator corresponding to the C-phase.

[0015] Further, the wiring spacing between the AC-phase tail lead-out wire, the BA-phase tail lead-out wire and the CB-phase tail lead-out wire is 100-200mm.

[0016] Further, the two ends of the front and rear clamping plates of the upper and lower clamping assemblies are locked and connected to each other by the first locking rod.

[0017] Further, the middle part of the front and rear clamping plates of the upper and lower clamping assemblies is locked and connected to each other by the second locking rod through the iron core.

[0018] Further, the thickness of the insulation cylinder arranged between the inner high-voltage coil and the iron core is greater than the thickness of the insulation cylinder arranged between the inner high-voltage coil and the outer high-voltage coil.

[0019] Further, the starting terminal, the ending terminal and the tapping terminal are arranged on the same side terminal panel of the high-voltage casting body, the left and right two rows of terminals of the tapping terminal are arranged in up-down staggered mode, and the starting terminal and the ending terminal are respectively arranged above and below the tapping terminal and on the vertical center line between the left and right two rows of tapping terminals.

[0020] Further, the center connecting line between the left and right two rows of tapping terminals is inclined at an angle of 28-35°, the distance between the center connecting lines of the left and right two rows of tapping terminals is 40-50mm, and transparent protective covers are arranged on the left and right two rows of tapping terminals.

[0021] Compared with the prior art, the beneficial effects of the utility model lie in that the inner high-voltage coil and the outer high-voltage coil are integrally cast through layered winding, and the inner starting lead-out wire and the inner ending lead-out wire of the inner high-voltage coil are respectively correspondingly processed into up-down lead-out wires through bending, compared with the prior art that the lead-out wires of the inner high-voltage coil are all led out from the lower part of the inner high-voltage coil, the embodiment of the application can avoid lead crossing through layering, can ensure that the inner starting lead-out wire is safely led out, and can make the inner ending lead-out wire horizontally walk along the high-voltage wiring insulator of the transformer base, so that wiring is more stable, and the electrical safety distance requirement of 35kV grade electrical clearance ≥300mm is met; in addition, the cold-pressing connection is used instead of welding for each terminal, so that the risk of high-temperature damage to the turn insulation is eliminated, and long-term operation reliability is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a three-dimensional schematic view of the dry-type grounding transformer in the preferred embodiment of the utility model;

[0023] Figure 2 It is a plane schematic view of the dry-type grounding transformer in the preferred embodiment of the utility model;

[0024] Figure 3 It is a structural schematic view of the inner high-voltage coil after the outer high-voltage coil of the C-phase coil assembly is removed in the preferred embodiment of the utility model;

[0025] Figure 4 It is a three-dimensional schematic view of the dry-type grounding transformer in the preferred embodiment of the utility model; Figure 3 It is an enlarged schematic view of position A in the middle.

[0026] In the figure:

[0027] 10, core;

[0028] 20. Coil assembly; 201. Inner high-voltage coil; 2011. Inner starting lead wire; 2012. Inner ending lead wire; 202. Outer high-voltage coil; 2021. Outer starting lead wire; 2022. Outer ending lead wire; 203. Low-voltage casting body; 204. High-voltage casting body; 2041. Terminal panel; 20411. Starting terminal; 20412. Ending terminal; 20413. Tap terminal; 405. Transparent protective cover; 206. Insulating cylinder;

[0029] 30. Transformer base; 301. Base beam; 31. High-voltage wiring insulator; 32. Connecting plate;

[0030] 40. Upper clamping assembly; 401. Front and rear clamping plates; 402. First locking rod; 403. Second locking rod; 41. Lower clamping assembly;

[0031] 50. Inner high-voltage lead-out insulator; 51. Outer high-voltage lead-out insulator. Detailed Implementation

[0032] 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.

[0033] like Figures 1-4 As shown, a new type of 35kV dry-type grounding transformer has been widely used in wind power generation, photovoltaic power generation and energy storage industries. The dry-type grounding transformer includes a core 10, an ABC three-phase coil assembly 20, and a transformer base 30. Each phase coil assembly 20 of the ABC three-phase coil assembly 20 is equipped with an inner high-voltage coil 201 and an outer high-voltage coil 202. The upper and lower ends of the coil assembly 20 are respectively equipped with an upper clamping assembly 40 and a lower clamping assembly 41. The coil assembly 20 is mounted on the transformer base 30 through the lower clamping assembly 41. The ABC three-phase coil assemblies 20 are arranged in a straight line on the base, for example, with a spacing of 500mm. Each phase coil is fixed to the base with bolts through the lower clamping assembly 41 (made of channel steel). The upper and lower clamping assemblies 41 are made of C-shaped steel plates. The front and rear clamping plates 401 are pre-tightened by M12 locking rods, with a clamping force ≥2000N. The three-phase parallel layout reduces magnetic circuit imbalance. The clamping assembly locking design prevents axial displacement of the coils and adapts to short-circuit electrodynamic impacts. The transformer base 30 is equipped with several high-voltage wiring insulators 31 for convenient wiring and fixing of the lead wires.

[0034] The iron core 10 adopts a three-phase three-column structure and is made of cold-rolled silicon steel sheets laminated together and coated with insulating paint on the surface. Each phase coil assembly 20 is divided into an inner high-voltage coil 201 and an outer high-voltage coil 202. The inner high-voltage coil 201 is directly wound around the outer periphery of the iron core 10 and adopts a continuous winding method. After winding, the entire inner high-voltage coil 201 is integrally cast with epoxy resin to form a low-pressure cast body 203. The specific casting thickness can be determined according to actual use requirements, for example, the casting thickness is 15-20 mm.

[0035] The outer high-voltage coil 202 is wound outside the inner high-voltage coil 201, and an insulating cylinder 206 with a certain thickness is arranged between the inner coil and the outer coil. After winding, the entire outer high-voltage coil 202 is integrally cast with epoxy resin to form a high-pressure cast body 204. The specific casting thickness can be determined according to actual use requirements, for example, the casting thickness is 25-30 mm. Heat dissipation air ducts are arranged in the inner high-pressure cast body 204 and the outer high-pressure cast body 204.

[0036] In the embodiment of the present application, the lead connection method is as follows. The upper and lower ends of the inner high-voltage coil 201 correspond to the inner start head lead-out wire 2011 and the inner tail head lead-out wire 2012, respectively. The inner start head lead-out wire 2011 (located at the top) of the inner high-voltage coil 201 is bent outward by 90°, then bent upward by 90° again and extends upward along the axial direction of the coil to the inner high-voltage lead-out wire insulator 50 (installed on the side plate of the upper clamp assembly 40) through bolt fixation.

[0037] In addition, the inner tail head lead-out wire 2012 (located at the bottom) is bent outward and then horizontally runs along the high-voltage wiring insulator 31 (ceramic material, height 150 mm) of the transformer base 30, and is connected to the outer tail head lead-out wire 2022 of the outer high-voltage coil 202 through copper bar lap joint, using cold-pressing terminals or nut connection to avoid welding. In addition, the outer start head lead-out wire 2021 of the ABC three-phase outer high-voltage coil 202 is connected to the neutral point at the top and extends upward to be commonly connected to the outer high-voltage lead-out wire insulator 51 (installed on the side plate of the upper clamp assembly 40).

[0038] Therefore, compared with the prior art in which the outgoing lines of the inner high-voltage coil are all led out from the lower part, the embodiment of the present application can avoid the cross-layer crossing of the lead lines, ensure the safe leading-out of the inner start-end outgoing line 2011, and enable the inner end-end outgoing line to be horizontally routed along the high-voltage wiring insulator 31 of the transformer base 30, so that the wiring is more stable and meets the electrical safety distance requirement of 35kV-level electrical clearance ≥ 300mm. In addition, the cold-pressing connection is used instead of welding for each terminal, so as to eliminate the risk of high-temperature damage to the turn insulation and improve the long-term operation reliability.

[0039] The inner high-voltage outgoing line insulator 50 (located at the top) and the outer high-voltage outgoing line insulator 51 (top neutral point) are both fixed on the same side of the coil assembly 20 on the upper clamp assembly 40, for example, with a spacing of 400mm. Therefore, by centrally arranging the inner start-end outgoing line 2011 and the outer start-end outgoing line 2021 on one side, the complexity of multi-directional wiring can be reduced, the risk of uneven electric field distribution can be reduced, and maintenance operation is facilitated, so that the overall structure and layout of the dry-type transformer are more compact.

[0040] The transformer base 30 is mainly composed of two C-shaped or T-shaped steel bottom beams 301 (with a spacing of 800mm) which are welded through the transverse connecting plates 32. Two high-voltage wiring insulators 31 (A-phase insulator numbers K1 / K2, B-phase K3 / K4, and C-phase K5 / K6) are arranged below each phase coil, and the high-voltage wiring insulators 31 are fixedly installed on the connecting plates 32 of the base.

[0041] During wiring, the AC-phase inner end-end outgoing line is connected to the C-phase outer end-end terminal 20412 along the path of K1→K2→K4→K6; the BA-phase inner end-end outgoing line is connected to the A-phase outer end-end terminal 20412 after passing through K3; and the CB-phase inner end-end outgoing line is connected to the B-phase outer end-end terminal 20412 after passing through K5. Therefore, by arranging a plurality of high-voltage wiring insulators 31 on the transformer base 30, the outgoing line connection between the inner high-voltage coil 201 and the outer high-voltage coil 202 is optimized, the wiring is more concise, the overlapping of phase lead lines is avoided, the phase lead line spacing is ensured to be ≥ 150mm, and the probability of phase-to-phase short circuit is reduced.

[0042] According to the wiring of the outgoing lines of each phase, the horizontal spacing of the end-end outgoing lines of the AC phase, the BA phase and the CB phase is set to 150mm (error ±10mm). By precisely controlling the spacing, the field strength between adjacent outgoing lines is ≤ 3kV / mm, the electric field is uniformly distributed, and the 35kV equipment insulation requirement is met.

[0043] The coil assembly 20 is fixed by the upper clamp assembly 40 (Q235 steel plate) and the lower clamp assembly 41 (Q345 steel plate), and the lower clamp assembly 41 is installed on the transformer base 30. The transformer base 30 is composed of two parallel bottom beams 301 (channel steel 200*75*9mm), so the lower clamp assembly 41 can be installed on the two parallel bottom beams 301 by M16 bolts, and at least one set of high-voltage wiring insulator 31 is arranged on the front side of each bottom beam 301, and the double bottom beam 301 structure can improve the anti-vibration ability by 3 times, and solve the problem of poor structural stability in the past.

[0044] In order to further improve the installation stability of the transformer, Φ20mm through holes are arranged at both ends of the front and rear clamping plates 401 of the upper clamp assembly 40 and the lower clamp assembly 41, and four M18 first locking rods 402 (length 500mm) are penetrated and locked, the locking torque is 120N·m, and if necessary, disc springs can be arranged between the clamping plates and the locking rods, and the planeness error of the clamp assembly is ≤0.1mm / m by locking the four corners, so as to solve the problem of clamp deformation.

[0045] The middle part of the front and rear clamping plates 401 of each clamp assembly is welded with two groups of locking ear plates (thickness 12mm), the locking ear plates are provided with Φ14mm holes, and two M12 second locking rods 403 are transversely locked, the locking torque is 80N·m, the middle part of the second locking rod 403 is provided with an insulating sleeve, and the distance between the locking ear plates is 200mm. In this way, the second locking rod 403 is used for locking in the middle part of the clamp assembly, so that the axial displacement of the coil is <0.05mm, and the problem of axial looseness of the coil is solved.

[0046] The above double-stage locking structure makes the displacement between the core 10 and the clamp assembly ≤0.1mm, improves the anti-vibration performance, and adapts to the working condition of seismic intensity 8.

[0047] Under normal circumstances, the thickness of the insulation cylinder 206 arranged between the inner high-voltage coil 201 and the core 10 is three to five times the thickness of the insulation cylinder 206 arranged between the inner high-voltage coil 201 and the outer high-voltage coil 202; for example, the thickness of the insulation cylinder 206 between the inner high-voltage coil 201 and the core 10 is 15mm (Nomex paper is used), and the thickness of the insulation cylinder 206 between the inner and outer high-voltage coils 202 is 4mm.

[0048] In this way, the inner layer high-thickness insulation cylinder 206 bears the full voltage (35kV) between the core 10 and the coil, and the outer layer thin cylinder only bears the interlayer voltage (10kV), and the material cost is optimized by matching the insulation strength.

[0049] The high-voltage casting body 204 provided by the embodiment of the application is provided with a terminal panel 2041 on the left side or the right side, and three groups of terminals are arranged on the terminal panel 2041, namely, a head connection terminal 20411, a tail connection terminal 20412 and a tapping connection terminal 20413. The tapping connection terminal 20413 is arranged in two rows of terminals on the left and right sides and is arranged in an up-down staggered manner, the left row of terminals is moved downward by 20 mm relative to the right row of terminals, the center connecting line of the two rows of terminals has an inclination angle a of 32° (the inclination angle ranges from 28° to 35°), and an inclination angle of 30° optimizes the electric field distribution between the terminals and reduces the risk of partial discharge. The center connecting line distance h between the two rows of tapping connection terminals 20413 is 45 mm (the range is 40-50 mm), the center distance of 45 mm ensures the installation space of an operating tool (such as a wrench), and the maintenance convenience is improved by 40%, and at the same time, the creepage distance between adjacent terminals is greater than or equal to 50 mm, so that sufficient electrical distance is ensured. Therefore, by arranging the two rows of tapping connection terminals 20413 in a staggered manner, the risk of arc creep between adjacent terminals is avoided, the staggered arrangement prevents misoperation of the tapping plug, and the inclination design saves the horizontal space of the panel.

[0050] In addition, the head connection terminal 20411 and the tail connection terminal 20412 are respectively arranged above and below the tapping connection terminal 20413, and the head connection terminal 20411 and the tail connection terminal 20412 are located on the vertical center line of the two rows of tapping connection terminals 20413. Therefore, by arranging the head connection terminal 20411 and the tail connection terminal 20412 on the vertical center line of the corresponding tapping connection terminal 20413, the lead length is shortened, the wiring efficiency is improved by 25%, and the creepage distance between the terminals is ensured to be the same. In addition, the two rows of tapping connection terminals 20413 are provided with a polycarbonate transparent protective cover 405 (thickness 3 mm), and the transparent protective cover 405 can observe the state of the terminals without disassembly, thereby reducing the maintenance downtime.

[0051] The above-mentioned embodiments are only preferred embodiments of the application, and cannot be used to limit the scope of protection of the application, and any non-essential changes and replacements made by those skilled in the art on the basis of the application all belong to the scope of protection of the application.

Claims

1. A 35 kV novel dry-type grounding transformer, characterized in that, The transformer comprises a core, a coil assembly and a transformer base, the coil assembly has three phases, each phase coil assembly is respectively provided with an inner high-voltage coil and an outer high-voltage coil, the inner high-voltage coil is wound around the outer periphery of the core and integrally cast with a low-voltage casting body, and the outer high-voltage coil is wound around the outer periphery of the inner high-voltage coil and integrally cast with a high-voltage casting body; The transformer base is provided with a plurality of high-voltage wiring insulators corresponding to each phase coil assembly; The upper and lower ends of the inner high-voltage coil are respectively connected with an inner head lead-out wire and an inner tail lead-out wire, the inner head lead-out wire is bent outward from the top of the coil assembly and extends upward to be connected with an inner high-voltage lead-out wire insulator, the inner tail lead-out wire is bent outward from the bottom of the coil assembly and connected with an outer tail lead-out wire of the high-voltage casting body along the arrangement direction of the high-voltage wiring insulator, and the outer head lead-out wires of the three phase coil assemblies are connected with each other and extend upward to be connected with an outer high-voltage lead-out wire insulator.

2. The 35 kV novel dry-type grounding transformer as claimed in claim 1, wherein, The inner high-voltage lead-out wire insulator and the outer high-voltage lead-out wire insulator are arranged on the same side of the coil assembly.

3. The 35 kV novel dry-type grounding transformer as claimed in claim 1, wherein, The coil assembly is arranged in parallel with ABC three phases on the transformer base, and the upper and lower ends of the coil assembly are respectively provided with an upper clamp assembly and a lower clamp assembly, and the coil assembly is installed on the transformer base through the lower clamp assembly.

4. The 35 kV novel dry-type grounding transformer as claimed in claim 3, wherein, The transformer base is composed of two parallel arranged bottom beams, the two bottom beams are connected through two parallel arranged connecting plates, two high-voltage wiring insulators are arranged along the direction of the two connecting plates and corresponding to each phase coil assembly; The inner tail lead-out wire of the A phase coil assembly is connected with the outer tail lead-out terminal of the C phase coil assembly along the arrangement direction of the two high-voltage wiring insulators corresponding to the A phase and the distal high-voltage wiring insulator corresponding to the BC phase; The inner tail lead-out wire of the B phase coil assembly is connected with the outer tail lead-out terminal of the A phase coil assembly along the arrangement direction of the proximal high-voltage wiring insulator corresponding to the B phase; The inner tail lead-out wire of the C phase coil assembly is connected with the outer tail lead-out terminal of the B phase coil assembly along the arrangement direction of the proximal high-voltage wiring insulator corresponding to the C phase.

5. The 35 kV novel dry-type grounding transformer as claimed in claim 4, wherein, The wiring spacing between the AC phase tail lead-out wire, the BA phase tail lead-out wire and the CB phase tail lead-out wire is 100-200mm.

6. The 35 kV novel dry-type grounding transformer as claimed in claim 3, 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 with each other through first locking rods.

7. The 35 kV novel dry-type grounding transformer as claimed in claim 3, wherein, The middle part of the front and rear clamping plates of the upper clamp assembly and the lower clamp assembly is locked and connected with each other through second locking rods after penetrating the core.

8. The 35 kV novel dry-type grounding transformer as claimed in claim 1, wherein, The thickness of the insulation cylinder arranged between the inner high-voltage coil and the core is greater than the thickness of the insulation cylinder arranged between the inner high-voltage coil and the outer high-voltage coil.

9. The 35 kV novel dry-type grounding transformer as claimed in claim 1, wherein, The same side terminal panel of the high-voltage casting body is provided with a head lead-out terminal, a tail lead-out terminal and a tapping terminal, the left and right two rows of terminals of the tapping terminal are arranged in up-down staggered manner, and the head lead-out terminal and the tail lead-out terminal are respectively arranged above and below the tapping terminal and on the vertical center line between the left and right two rows of tapping terminals.

10. The 35 kV novel dry-type grounding transformer as claimed in claim 9, wherein, The center connecting line between the left and right rows of the tapping terminals is inclined at an angle of 28-35°, and the distance between the center connecting lines of the left and right rows of the tapping terminals is 40-50 mm; and the upper cover of the left and right rows of the tapping terminals is provided with a transparent protective cover.

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