Dry-type autotransformer with asymmetrical coil splitting

Abstract

The invention discloses a dry-type autotransformer with asymmetrically split coils, which comprises a first core column and a second core column. The first core column is provided with a first coil, a second coil and a third coil in sequence from the inside to the outside. The first coil is located on the core side of the second coil, and the third coil is located on the outside of the second coil. The number of turns of the first coil is 1 / 4 of that of the second coil, and the number of turns of the third coil is 3 / 4 of that of the second coil. The upper end of the first coil is connected to the upper end of the third coil, and the lower end of the first coil is connected to the lower end of the second coil to form a common end O. The second core column is provided with a fourth coil, a fifth coil and a sixth coil in sequence from the inside to the outside. The fourth coil is located on the core side of the fifth coil, and the sixth coil is located on the outside of the fifth coil. The invention provides a dry-type autotransformer with asymmetrically split coils, which has a low voltage difference between coils and a small impedance.

Description

Technical Field

[0001] The invention relates to a dry-type autotransformer with asymmetrically split coils, belonging to the technical field of rail transportation. Background Art

[0002] At present, my country's electrified railways use AT power supply. AT power supply dedicated autotransformer is an important electrical equipment in the AT power supply system. With the rapid development of my country's electrified railways, more and more electrified railways are crossing mountains and ridges. In some places, tunnels are connected to bridges, and it is difficult to find a flat land to place the autotransformer. Often, the autotransformer can only be placed in the tunnel. For safety reasons, these autotransformers must have high fire and explosion resistance. Dry-type transformers are a typical safety fire and explosion transformer.

[0003] Dry-type transformers are very different from oil-immersed transformers. Since the insulating medium of dry-type transformers is air, compared with oil-immersed transformers with oil as the insulating medium, the insulation performance of air is much lower than that of transformer oil, so the design of the voltage difference between the coils and between the coils and the core is particularly important. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a dry-type autotransformer with asymmetrically split coils, which has a low voltage difference between coils and a small impedance.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A dry-type autotransformer with asymmetrically split coils comprises a first core column and a second core column, wherein the first core column is provided with a first coil, a second coil and a third coil in sequence from the inside to the outside, wherein the first coil is located on the core side of the second coil, and the third coil is located on the outside of the second coil, wherein the number of turns of the first coil is 1 / 4 of that of the second coil, and the number of turns of the third coil is 3 / 4 of that of the second coil, wherein the upper end of the first coil is connected to the upper end of the third coil, and the lower end of the first coil is connected to the lower end of the second coil, and a common terminal O is formed, and the second core column is provided with a fourth coil, a fifth coil and a sixth coil in sequence from the inside to the outside, wherein the fourth coil is located on the core side of the fifth coil, and the sixth coil is located on the outside of the fifth coil, wherein the number of turns of the fourth coil is 1 / 4 of that of the fifth coil, and the number of turns of the sixth coil is 3 / 4 of that of the fifth coil, wherein the upper end of the fourth coil is connected to the upper end of the sixth coil, and the lower end of the fourth coil is connected to the lower end of the fifth coil, and a common terminal O' is formed.

[0007] Furthermore, the first core leg and the second core leg are connected in parallel.

[0008] Furthermore, a terminal A is provided at the upper end of the second coil.

[0009] Furthermore, a terminal B is provided at the lower end of the third coil.

[0010] Furthermore, a terminal A' is provided at the upper end of the fifth coil.

[0011] Furthermore, a terminal B' is provided at the lower end of the sixth coil.

[0012] By adopting the above technical solution, the coil of the present invention adopts an asymmetric splitting method, splitting the coil into several parts and arranging them in a staggered manner to increase the electromagnetic coupling between the coils and reduce the voltage difference between the coils to a lower level, while taking into account the characteristic of low impedance of the autotransformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The schematic diagram of the dry-type autotransformer with asymmetrically split coils of the present invention;

[0014] Figure 2 The wiring diagram of terminal A to ground 85kV for the present invention;

[0015] Figure 3 Wiring diagram of terminal B to ground 85kV for the present invention;

[0016] Figure 4 The wiring diagram for testing 200% turn voltage (2 times induction test) of the present invention;

[0017] Figure 5 It is a schematic diagram of the prior art of the present invention. DETAILED DESCRIPTION

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments in conjunction with the accompanying drawings.

[0019] like Figure 1As shown, a dry-type autotransformer with asymmetrically split coils comprises a first core column 1 and a second core column 2. The first core column 1 is provided with a first coil 11, a second coil 12 and a third coil 13 in sequence from the inside to the outside. The first coil 11 is located on the core side of the second coil 12, and the third coil 13 is located on the outside of the second coil 12. The number of turns of the first coil 11 is 1 / 4 of that of the second coil 12, and the number of turns of the third coil 13 is 3 / 4 of that of the second coil 12. The upper end of the first coil 11 is connected to the upper end of the third coil 13, and the lower end of the first coil 11 is connected to the lower end of the third coil 13. The lower ends of the two coils 12 are connected to form a common terminal O. The second core column 2 is sequentially provided with a fourth coil 21, a fifth coil 22 and a sixth coil 23 from the inside to the outside. The fourth coil 21 is located on the core side of the fifth coil 22, and the sixth coil 23 is located on the outside of the fifth coil 22. The number of turns of the fourth coil 21 is 1 / 4 of that of the fifth coil 22, and the number of turns of the sixth coil 23 is 3 / 4 of that of the fifth coil 22. The upper end of the fourth coil 21 is connected to the upper end of the sixth coil 23, and the lower end of the fourth coil 21 is connected to the lower end of the fifth coil 22 to form a common terminal O'.

[0020] like Figure 1 As shown, the first core column 1 and the second core column 2 are connected in parallel. Since the two columns are connected in parallel, the same potential between the outer coils at the same height is theoretically the same, that is, the third coil 13 and the sixth coil 23 are at the same potential at any position, that is, the phase-to-phase voltage is 0 kV.

[0021] like Figure 1 As shown, a terminal A is provided at the upper end of the second coil 12 .

[0022] like Figure 1 As shown, a terminal B is provided at the lower end of the third coil 13 .

[0023] like Figure 1 As shown, the upper end of the fifth coil 22 is provided with a terminal A'.

[0024] like Figure 1 As shown, the lower end of the sixth coil 23 is provided with a terminal B'.

[0025] like Figure 1 As shown, since the impedance of the autotransformer is very small, the coil needs to be split into several parts and arranged in a staggered manner to increase the electromagnetic coupling between the coils, thereby reducing the reactance. In order to reduce the voltage difference between the coils, the present invention splits the coil between BO into two parts, a first coil 11 and a third coil 13. The number of turns of the first coil 11 is 1 / 4 of the total number of turns of the coil between BO, and the number of turns of the third coil 13 is 3 / 4 of the total number of turns of the coil between BO. The total number of turns of the coil between BO is the same as the number of turns of the second coil 12.

[0026] According to the requirements of the insulation level of the autotransformer, the power frequency withstand voltage of the A and B terminals to the ground is 85kV, and the power frequency withstand voltage of the common terminal O to the ground is 25kV. Therefore, the power frequency withstand voltage test of the A and B terminals needs to be realized by induction. In order to assess the voltage of each terminal and turn, the test is carried out in three times:

[0027] Test terminal A to ground 85kV, wiring as follows Figure 2 As shown, at this time, the voltage difference between terminal A and the upper end of the adjacent coil is 42.5+1 / 4×42.5=53.125kV, the voltage between the common terminal O and terminal B is 42.5kV, the voltage between the inner coil and the ground is 3 / 4×42.5=31.875kV, and the voltage between phases is 0kV;

[0028] Test terminal B to ground 85kV, wiring as follows Figure 3 As shown, at this time, the voltage difference between terminal A and the upper end of the adjacent coil is 42.5+1 / 4×42.5=53.125kV, the voltage between the common terminal O and terminal B is 42.5kV, the voltage between the inner coil and the ground is 42.5+1 / 4×42.5=53.125kV, and the voltage between the phases is 0kV;

[0029] Test 200% turn voltage 2 times induction test, wiring as Figure 4 As shown, at this time, the voltage difference between terminal A and the upper end of the adjacent coil is 55+1 / 4×55=68.75kV, the common terminal O to terminal B is 55kV, the inner coil to ground is -1 / 4×55=-13.75kV, and the phase-to-phase voltage is 0kV.

[0030] The adjacent coils of the terminal A are the inner coil and the outer coil, the inner coil is the first coil 11, and the outer coil is the third coil 13. The test data of the terminals and the turn-to-turn voltage of the dry-type autotransformer with asymmetrically split coils are organized into Table 1:

[0031] Table 1

[0032]

[0033] like Figure 5 As shown, the common oil-immersed autotransformer winding connection method uses two columns in series, each column is split into 4 coils, and the number of turns of each coil is equal.

[0034] Test terminal A to ground 85kV, wiring as follows Figure 2 As shown, the voltage difference between terminal A and adjacent coils is: 1.5×42.5=63.75kV, the voltage difference between terminal O and ground is 42.5kV, the voltage difference between inner coil and ground is 42.5+1 / 4×42.5=53.125kV, and the phase-to-phase voltage difference is 85kV;

[0035] Test terminal B to ground 85kV, wiring as follows Figure 3As shown, the voltage difference between terminal B and adjacent coils is: 63.75kV, the voltage difference between terminal O and ground is 42.5kV, the voltage difference between inner coil and ground is 53.125kV, and the voltage difference between phases is 85kV;

[0036] Test 200% turn voltage 2 times induction test, wiring as Figure 4 As shown, the voltage difference between the A and B ends to adjacent coils is: 1.5×55=82.5kV, and the phase-to-phase voltage difference is 110kV.

[0037] The test data of each terminal and turn-to-turn voltage of the common oil-immersed autotransformer are organized into Table 2:

[0038] Table 2

[0039]

[0040] From Table 1 and Table 2, we can see that:

[0041] The invention has the same voltage difference between the inner coil and the ground as the ordinary oil-immersed autotransformer, and the maximum test voltages between the coils and between the phases are lower than those of the ordinary oil-immersed autotransformer, especially the phase-to-phase voltage is reduced from the test voltage of 110kV to the equipotential, which has obvious advantages for the insulation performance of the dry-type transformer.

[0042] The specific embodiments described above further illustrate the technical problems, technical solutions and beneficial effects solved by the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A dry-type autotransformer with asymmetrically split coils, characterized in that: It comprises a first core column (1) and a second core column (2); the first core column (1) is provided with a first coil (11), a second coil (12) and a third coil (13) in sequence from the inside to the outside; the first coil (11) is located on the core side of the second coil (12); the third coil (13) is located on the outside of the second coil (12); the number of turns of the first coil (11) is 1 / 4 of that of the second coil (12); the number of turns of the third coil (13) is 3 / 4 of that of the second coil (12); the upper end of the first coil (11) is connected to the upper end of the third coil (13); the lower end of the first coil (11) is connected to the lower end of the second coil (12) to form a common end O; the first coil (11) and the third coil (13) are connected to each other; The second core column (2) is provided with a fourth coil (21), a fifth coil (22) and a sixth coil (23) in sequence from the inside to the outside. The fourth coil (21) is located on the core side of the fifth coil (22), and the sixth coil (23) is located on the outside of the fifth coil (22). The number of turns of the fourth coil (21) is 1 / 4 of that of the fifth coil (22), and the number of turns of the sixth coil (23) is 3 / 4 of that of the fifth coil (22). The upper end of the fourth coil (21) is connected to the upper end of the sixth coil (23), and the lower end of the fourth coil (21) is connected to the lower end of the fifth coil (22) to form a common end O'. The first core column (1) and the second core column (2) are connected in parallel.

2. The dry-type autotransformer with asymmetrically split coils according to claim 1, characterized in that: A terminal A is provided at the upper end of the second coil (12).

3. The dry-type autotransformer with asymmetrically split coils according to claim 1, characterized in that: A terminal B is provided at the lower end of the third coil (13).

4. The dry-type autotransformer with asymmetrically split coils according to claim 1, characterized in that: The upper end of the fifth coil (22) is provided with a terminal A'.

5. The dry-type autotransformer with asymmetrically split coils according to claim 1, characterized in that: The lower end of the sixth coil (23) is provided with a terminal B'.

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