Power transformer

Abstract

The utility model discloses a power transformer, which can simplify the arrangement mode of voltage regulating leads, reduce the electrodynamic force action between out-phase voltage regulating leads and reduce the production cost of the power transformer by adjusting the arrangement position of an on-load voltage regulating switch. The power transformer comprises an oil tank, an iron core (4) and a coil. The coils comprise a first coil (1), a second coil (2) and a third coil (3) which are sequentially arranged in the oil tank, the power transformer further comprises an on-load tap changer (7), and the on-load tap changer (7) is arranged between the second coil (2) and the third coil (3) on the long axis side of the oil tank. Voltage regulation leads of the first coil (1), the second coil (2) and the third coil (3) are led out from one side close to the on-load tap changer (7) and then are connected with the on-load tap changer (7).

Description

Technical Field

[0001] The utility model belongs to the technical field of transformer manufacturing, and particularly relates to a power transformer. Background Art

[0002] With the rapid development of the world economy, the demand for energy has promoted the rapid development of the power transmission and transformation industry. Especially, the rapid development of new energy globally has enabled high-voltage and large-capacity transformers to be widely used in the power system.

[0003] When the capacity of the transformer exceeds 100MVA, considering the economy and transportation feasibility of the transformer, a three-phase five-column core structure is usually adopted in the industry to reduce the transportation height of the product. As Figure 1 shown, in a transformer with such a structure, the on-load tap-changer is usually arranged on the short-axis side of the transformer tank.

[0004] When adopting such an arrangement method of the on-load tap-changer, the lead design and arrangement of the three-phase windings of the transformer are relatively complex, and there are many lead clamping parts. Therefore, a large amount of lead cables are required, and it is also more troublesome during actual installation, increasing the working hours of actual production. And since the three-phase leads need to be aggregated to the on-load tap-changer and connected to the on-load tap-changer at the same time, the clamping parts at the on-load tap-changer need to bear the total weight of the regulating leads of the three-phase windings and the electrodynamic force between the regulating leads of different phases (where the regulating leads of the first coil and the third coil are close to each other), which makes the clamping parts of the regulating leads prone to cracking due to insufficient strength, thus unable to fully ensure the strength of the leads. At the same time, since the on-load tap-changer is arranged on the short-axis side of the tank, in order to meet the requirement of the electrical insulation distance of the on-load tap-changer inside the transformer, the tank of the transformer needs to be lengthened, which also causes an increase in the material consumption of the product and increases the production cost. Content of the Utility Model

[0005] The technical problem to be solved by the utility model is to provide a power transformer aiming at the above deficiencies existing in the prior art. By adjusting the installation position of the on-load tap-changer, the arrangement method of the regulating leads can be simplified, the electrodynamic force between the regulating leads of different phases can be reduced, and the production cost of the power transformer can be reduced.

[0006] In a first aspect, an embodiment of the utility model provides a power transformer, which includes a tank, a core, and coils. The coils include a first coil, a second coil, and a third coil arranged in sequence in the tank. The power transformer further includes an on-load tap-changer, and the on-load tap-changer is arranged between the second coil and the third coil on the long-axis side of the tank. After the regulating leads of the first coil, the second coil, and the third coil are led out from the side close to the on-load tap-changer, they are all connected to the on-load tap-changer.

[0007] In some embodiments, the voltage regulating leads of the first coil, the second coil, and the third coil are all fixed on the core clamping device through lead brackets and then connected to the on-load tap-changer.

[0008] In some embodiments, the voltage regulating lead of the first coil is first horizontally fixed on the core clamping device through a clamping wooden part, and then fixed through a lead bracket and connected to the on-load tap-changer.

[0009] In some embodiments, the core is of a three-phase five-column structure, and the first coil, the second coil, and the third coil are respectively wound around the three middle core columns of the core.

[0010] In some embodiments, the oil tank includes an upper oil tank section and a lower oil tank section, and the upper oil tank section and the lower oil tank section are fixedly connected by bolts. The on-load tap-changer is fixed on the upper oil tank section, and the insulation distance between the on-load tap-changer and the lower oil tank section is greater than or equal to 100 mm.

[0011] In some embodiments, the on-load tap-changer is also fixed on the core clamping device through a switch bracket.

[0012] In some embodiments, the connection between the switch bracket and the core clamping device is detachable.

[0013] In some embodiments, the upper oil tank section extends outward along its short axis direction to form a convex part, and the convex part forms the installation housing of the on-load tap-changer.

[0014] In some embodiments, the top end of the on-load tap-changer extends out of the upper oil tank section. A switch elevation seat is arranged between the top end of the on-load tap-changer and the upper oil tank section.

[0015] In some embodiments, the connection between the top end of the on-load tap-changer and the switch elevation seat is detachable, and the connection between the upper oil tank section and the switch elevation seat is detachable.

[0016] Therefore, for the power transformer provided by the embodiment of the present utility model, by arranging the on-load tap-changer between the second coil and the third coil on the long axis side of the oil tank, the distance between the on-load tap-changer and the second coil and the third coil is reduced, thereby reducing the length of the regulating leads of the second coil and the third coil; and, compared with the prior art, the length of the regulating lead of the longest first coil in this embodiment is also less than the length of the regulating lead of the longest third coil in the prior art. Therefore, the length of the regulating lead of the first coil can also be reduced, thereby reducing the number of clamping members for fixing all the regulating leads, simplifying the layout of the regulating leads, and reducing the installation difficulty of the regulating leads. Further, because the length of all the regulating leads is reduced, the action of the electrodynamic force generated by the phase difference between the out-of-phase regulating leads can be reduced, improving the overall short-circuit resistance of the regulating leads. At the same time, the strength requirement for the clamping members for fixing each regulating lead can also be reduced, and the situation of clamping member damage caused by excessive electrodynamic force can be avoided. Finally, the on-load tap-changer in this embodiment is arranged between the second coil and the third coil on the long axis side of the oil tank, so there is no need to lengthen the oil tank, and the production cost of the power transformer can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 : A schematic diagram of an on-load tap-changer provided in the prior art;

[0018] Figure 2 : A schematic diagram of an on-load tap-changer provided by the embodiment of the present utility model;

[0019] Figure 3 : A schematic diagram of a power transformer provided by the embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] To enable those skilled in the art to better understand the technical solutions of the present utility model, the present utility model will be further described in detail below with reference to the drawings and embodiments.

[0021] Embodiment 1:

[0022] As Figure 2 shown, the embodiment of the present utility model provides a power transformer, which is applied to the power system. As Figure 2 shown, the power transformer includes an oil tank, an iron core 4, and coils. The coils include a first coil 1, a second coil 2, and a third coil 3 arranged in sequence in the oil tank. The power transformer further includes an on-load tap-changer 7. The on-load tap-changer 7 is arranged between the second coil 2 and the third coil 3 on the long axis side of the oil tank. After the regulating leads of the first coil 1, the second coil 2, and the third coil 3 are led out from the side close to the on-load tap-changer 7, they are all connected to the on-load tap-changer 7.

[0023] Exemplarily, the power transformer in this embodiment can be an oil-immersed transformer with a large-capacity three-phase integrated structure of 110 kV - 330 kV.

[0024] Transformer oil is provided in the oil tank, which can cool the iron core 4 and the coils and provide an insulating environment.

[0025] It should be noted that the first coil 1, the second coil 2, and the third coil 3 can respectively correspond to the A phase, the B phase, and the C phase in sequence, or can also respectively correspond to the B phase, the C phase, and the A phase, or other corresponding relationships. The embodiments of the present invention do not limit the corresponding relationships between the first coil 1, the second coil 2, the third coil 3, and the three-phase coils.

[0026] The iron core 4 is used to provide support for the coils and a magnetic path.

[0027] The on-load tap-changer 7 changes the transformation ratio of the power transformer by changing the position where the tap-changing lead wire is connected to the coil, thereby realizing the regulation of the output voltage.

[0028] As Figure 2 shown, the long-axis side of the oil tank is the side where the long side of the oil tank is located. Generally, the high-voltage side and the low-voltage side of the power transformer are respectively located on two different long-axis sides of the oil tank.

[0029] Exemplarily, the on-load tap-changer 7 can be arranged on the high-voltage side of the oil tank, or can also be arranged on the low-voltage side of the oil tank.

[0030] As Figure 2 shown, for the convenience of description, in this embodiment, the tap-changing lead wire of the first coil 1 is marked as tap-changing lead wire 11, the tap-changing lead wire of the second coil 2 is marked as tap-changing lead wire 21, and the tap-changing lead wire of the third coil 3 is marked as tap-changing lead wire 31.

[0031] Combined with Figure 1 and Figure 2 , by arranging the on-load tap-changer 7 between the second coil 2 and the third coil 3 on the long-axis side of the oil tank, compared with the prior art, the distance between the on-load tap-changer 7 and the second coil 2 and the third coil 3 is reduced. Therefore, the lengths of the tap-changing lead wire 21 and the tap-changing lead wire 31 can be reduced.

[0032] At the same time, in the prior art, as Figure 1 shown, the tap-changing lead wire of the third coil is the lead wire with the longest length, and the tap-changing lead wire of the third coil needs to cross the second coil 2 and the first coil 1 and then be connected to the on-load tap-changer 7. In this embodiment, as Figure 2As shown, the voltage regulating lead 11 of the first coil 1 is the longest lead, but the voltage regulating lead 11 of the first coil 1 only needs to cross the second coil 2 to be connected to the on-load tap-changer 7. Therefore, the length of the longest voltage regulating lead 11 in this embodiment is also less than that of the voltage regulating lead of the third coil in the prior art, and the length of the voltage regulating lead 11 is also reduced.

[0033] It can be understood that, compared with the prior art, since the lengths of the voltage regulating lead 11, the voltage regulating lead 21, and the voltage regulating lead 31 are reduced, the number of clamping members for fixing the voltage regulating leads can be reduced, the layout of the voltage regulating leads can be simplified, the installation difficulty can be reduced, and it helps to improve production efficiency.

[0034] It can be understood that when current passes through the out-of-phase voltage regulating leads, since the current in each voltage regulating lead generates a magnetic field and there is a phase difference between the out-of-phase voltage regulating leads, the voltage regulating leads in different magnetic fields will be affected by the electromagnetic force, thereby generating electrodynamic force. The greater the current and the smaller the distance between the out-of-phase voltage regulating leads, the stronger the generated magnetic field, and the greater the electrodynamic force between the voltage regulating leads.

[0035] In this embodiment, since the lengths of the voltage regulating lead 11, the voltage regulating lead 21, and the voltage regulating lead 31 are reduced, as Figure 2 shown, the parts where the voltage regulating lead 11, the voltage regulating lead 21, and the voltage regulating lead 31 are close to each other are less, and the distance is larger. Therefore, the electrodynamic force generated due to the phase difference between the out-of-phase voltage regulating leads can be reduced, the adaptability of the voltage regulating leads to large currents can be improved, and the short-circuit resistance of the voltage regulating leads can be improved. At the same time, after the electrodynamic force between the out-of-phase voltage regulating leads is reduced, the strength requirements for the clamping members for fixing each voltage regulating lead can also be reduced, and the situation of clamping member damage caused by excessive electrodynamic force can be avoided.

[0036] In the prior art, the on-load tap-changer 7 needs to lengthen the oil tank because it is arranged on the short axis side of the oil tank. In this embodiment, the on-load tap-changer 7 is arranged between the second coil 2 and the third coil 3 on the long axis side of the oil tank. Therefore, there is no need to lengthen the oil tank, and the volume can be reduced and the production cost of the power transformer can be reduced.

[0037] On the other hand, as Figure 2 shown, the lead-out positions of the voltage regulating leads of the three-phase coils are all arranged on the same side. Compared with the common arrangement in the current industry of arranging the lead-out positions of different voltage regulating leads on the high-voltage side and the low-voltage side at the same time, the structure of the voltage regulating leads in this embodiment has stronger versatility; and since there is only one row of voltage regulating leads in the long axis direction for the voltage regulating leads with this structure, the space occupied by the voltage regulating leads is relatively small, and it is applicable to both the high-voltage middle lead-out and the high-voltage end lead-out structures of the coil. Therefore, the voltage regulating leads in this embodiment have strong adaptability to transformers with different structures.

[0038] Thus, for the power transformer provided by the embodiment of the present utility model, by arranging the on-load tap-changer 7 between the second coil 2 and the third coil 3 on the long axis side of the oil tank, the distance between the on-load tap-changer 7 and the second coil 2 and the third coil 3 is reduced, thereby reducing the lengths of the regulating leads 21 and 31; and, compared with the prior art, the length of the longest regulating lead 11 in this embodiment is also less than the longest regulating lead of the third coil in the prior art. Therefore, the length of the regulating lead 11 can also be reduced, thereby reducing the number of clamping members for fixing all the regulating leads, simplifying the arrangement mode of the regulating leads, and reducing the installation difficulty of the regulating leads. Further, because the lengths of the regulating lead 11, the regulating lead 21 and the regulating lead 31 are reduced, the action of the electrodynamic force generated due to the phase difference between the out-of-phase regulating leads can be reduced, the overall short-circuit resistance of the regulating leads can be improved, and at the same time, the strength requirements for the clamping members for fixing each regulating lead can be reduced, and the situation of clamping member damage caused by excessive electrodynamic force can be avoided. Finally, the on-load tap-changer 7 in this embodiment is arranged between the second coil 2 and the third coil 3 on the long axis side of the oil tank. Therefore, there is no need to lengthen the oil tank, and the volume can be reduced and the production cost of the power transformer can be reduced.

[0039] In some embodiments, the regulating leads of the first coil 1, the second coil 2 and the third coil 3 are all fixed on the core clamping member 5 through lead brackets and then connected to the on-load tap-changer 7.

[0040] The core clamping member 5 is generally arranged at the upper and lower ends of the core 4, and can tightly clamp the core to prevent the core from loosening or displacing during operation, ensuring the normal operation of the power transformer. It can also provide stable support for the core, bearing various acting forces such as the weight of the core and the electromagnetic force generated during operation.

[0041] Exemplarily, one end of a lead bracket is fixed to the core clamping member 5, and the other end is used to fix the regulating lead of the first coil 1, the second coil 2 or the third coil 3.

[0042] Through the above arrangement, stable support and positioning can be provided for the regulating leads of the first coil 1, the second coil 2 and the third coil 3 through the lead brackets, ensuring that the leads will not be displaced or damaged due to factors such as vibration and electromagnetic force during the operation of the transformer.

[0043] In some embodiments, as Figure 2 shown, the regulating lead 11 of the first coil 1 is first horizontally fixed on the core clamping member 5 through a clamping wooden member, and then fixed through a lead bracket and connected to the on-load tap-changer 7.

[0044] As Figure 2As shown, compared with the voltage regulating leads 21 and 31, the voltage regulating lead 11 of the first coil 1 has the longest length. By fixing the voltage regulating lead 11 of the first coil 1 with the clamping wooden part and the lead support simultaneously, the fixing effect on the voltage regulating lead 11 of the first coil 1 can be improved.

[0045] In some embodiments, as Figure 2 shown, the iron core 4 is of a three-phase five-column structure, and the first coil 1, the second coil 2 and the third coil 3 are respectively wound around the three middle iron core columns of the iron core 4.

[0046] In the iron core structure of a three-phase five-column transformer, in addition to the three iron core columns corresponding to the three-phase coils, there are two spare iron core columns on both sides, and the five iron core columns are connected by yokes up and down. In this way, the zero-sequence magnetic flux can form a circulation loop through the two outer iron core columns and the upper and lower yokes, so as to better handle the zero-sequence magnetic flux, reduce the influence of the zero-sequence magnetic flux on the operation of the power transformer, and reduce problems such as the loss and heating of the power transformer. In addition, the volume of the power transformer can be reduced, which is convenient for the transportation of the power transformer.

[0047] In some embodiments, as Figure 3 shown, the oil tank includes an upper oil tank 8 and a lower oil tank 9, and the upper oil tank 8 and the lower oil tank 9 are fixedly connected by bolts. The on-load tap-changer 7 is fixed on the upper oil tank 8, and the insulation distance between the on-load tap-changer 7 and the lower oil tank 9 is greater than or equal to 100 mm.

[0048] Exemplarily, the upper oil tank 8 is of a bell-type structure, and the lower oil tank 9 is of a ship-type structure, so as to facilitate the storage of transformer oil inside the oil tank.

[0049] The split design of the upper oil tank 8 and the lower oil tank 9 is convenient for the installation of the internal structure of the oil tank.

[0050] Exemplarily, the insulation distance between the on-load tap-changer 7 and the lower oil tank 9 can be 100 mm, 110 mm or 130 mm, etc.

[0051] Through the above settings, good insulation can be achieved between the on-load tap-changer 7 and the lower oil tank 9, meeting the use requirements of the power transformer.

[0052] In some embodiments, as Figure 3 shown, the on-load tap-changer 7 is also fixed on the iron core clamping piece 5 through the switch support 6.

[0053] Exemplarily, the shape of the switch support 6 is Z-shaped.

[0054] Exemplarily, the bottom end of the switch support 6 is fixed on the iron core clamping piece 5, and the on-load tap-changer 7 is fixed on the top end of the iron core clamping piece 5.

[0055] The switch bracket 6 can temporarily support the on-load tap-changer 7 to facilitate the installation of the on-load tap-changer 7.

[0056] In some embodiments, the switch bracket 6 is detachably connected to the core clamping piece 5.

[0057] Exemplarily, the switch bracket 6 is fixed to the core clamping piece 5 by bolts.

[0058] With the above arrangement, it is convenient to disassemble the switch bracket 6.

[0059] In some embodiments, the upper tank 8 extends outward along its short axis direction to form a convex portion, and the convex portion forms the installation housing of the on-load tap-changer 7.

[0060] With the above arrangement, the installation housing of the on-load tap-changer 7 can be formed on the upper tank 8. That is, when the on-load tap-changer 7 is arranged between the second coil 2 and the third coil 3 on the long axis side of the tank, only a small adjustment is required for the outer shape of the upper tank 8, and there is no need to adjust the structure of the lower tank 9, which improves the versatility of the upper tank 8.

[0061] In some embodiments, as Figure 3 shown, the top end of the on-load tap-changer 7 extends out of the upper tank 8. A switch riser 10 is arranged between the top end of the on-load tap-changer 7 and the upper tank 8.

[0062] Exemplarily, the switch riser 10 is arranged at the top end of the upper tank 8.

[0063] The switch riser 10 can raise the position of the on-load tap-changer 7 to increase the minimum distance between the on-load tap-changer 7 and the lower tank 9, that is, improve the insulation distance between the on-load tap-changer 7 and the lower tank 9, and can avoid the occurrence of electrical discharge due to insufficient electrical insulation distance between the on-load tap-changer 7 and the lower tank 9.

[0064] In some embodiments, the top end of the on-load tap-changer 7 is detachably connected to the switch riser 10, and the upper tank 8 is detachably connected to the switch riser 10.

[0065] Exemplarily, the top end of the on-load tap-changer 7 is connected to the switch riser 10 by bolts; the upper tank 8 is connected to the switch riser 10 by bolts.

[0066] Exemplarily, when it is necessary to increase the insulation distance between the on-load tap-changer 7 and the lower tank 9, a higher switch riser 10 can be replaced to increase the overall height of the on-load tap-changer 7.

[0067] Through the above settings, it is convenient to replace the switch lifting seat 10, so as to adjust the insulation distance between the on-load tap-changer 7 and the lower tank 9.

[0068] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A power transformer, comprising an oil tank, an iron core (4) and coils, characterized in that, The coil includes a first coil (1), a second coil (2) and a third coil (3) arranged in sequence in the oil tank. The power transformer further includes an on-load tap-changer (7). The on-load tap-changer (7) is arranged between the second coil (2) and the third coil (3) on the long-axis side of the oil tank. After the voltage regulating leads of the first coil (1), the second coil (2) and the third coil (3) are led out from the side close to the on-load tap-changer (7), they are all connected to the on-load tap-changer (7).

2. The power transformer according to claim 1, characterized in that, The voltage regulating leads of the first coil (1), the second coil (2) and the third coil (3) are all fixed on the core clamping piece (5) through lead brackets and then connected to the on-load tap-changer (7).

3. The power transformer according to claim 2, characterized in that, The voltage regulating lead of the first coil (1) is first horizontally fixed on the core clamping piece (5) through a clamping wooden piece, and then fixed through a lead bracket and connected to the on-load tap-changer (7).

4. The power transformer according to claim 1, characterized in that, The core (4) is of a three-phase five-column structure. The first coil (1), the second coil (2) and the third coil (3) are respectively wound around three core columns in the middle of the core (4).

5. The power transformer according to any one of claims 1-4, wherein The oil tank includes an upper oil tank section (8) and a lower oil tank section (9). The upper oil tank section (8) and the lower oil tank section (9) are fixedly connected by bolts; The on-load tap-changer (7) is fixed on the upper oil tank section (8). The insulation distance between the on-load tap-changer (7) and the lower oil tank section (9) is greater than or equal to 100 mm.

6. The power transformer according to claim 5, characterized in that, The on-load tap-changer (7) is further fixed on the core clamping piece (5) through a switch bracket (6).

7. The power transformer according to claim 6, characterized in that, The switch bracket (6) is detachably connected to the core clamping piece (5).

8. The power transformer according to claim 5, characterized in that, The upper oil tank section (8) extends outward along its short-axis direction to form a convex portion, and the convex portion forms the installation housing of the on-load tap-changer (7).

9. The power transformer according to claim 8, characterized in that, The top end of the on-load tap-changer (7) extends out of the upper oil tank section (8); A switch riser (10) is arranged between the top end of the on-load tap-changer (7) and the upper oil tank section (8).

10. The power transformer according to claim 9, wherein The top end of the on-load tap-changer (7) is detachably connected to the switch riser (10), and the upper oil tank section (8) is detachably connected to the switch riser (10).

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