Transformer

Abstract

The invention relates to a transformer (1). The transformer (1) comprises two low-voltage windings (3, 5) and a high-voltage winding (7), wherein the two low-voltage windings (3, 5) are interlaced.

Description

[0001] Description

[0002] Transformer

[0003] The invention relates to a transformer, in particular a transformer for a wind turbine.

[0004] The transformer of a wind turbine adapts the electrical voltage generated by its generator to the nominal voltage of a power grid into which the electricity produced by the wind turbine is fed. The transformer receives as its primary voltage the output voltage of a converter within the wind turbine. The converter adjusts the frequency of the generator's voltage to the grid frequency of the power grid. To maintain grid stability, the converter should compensate for as much reactive power as possible while simultaneously minimizing the transformer's short-circuit current.

[0005] The invention is based on the objective of providing a transformer that enables a converter of a wind turbine to compensate for as much reactive power as possible.

[0006] The problem is solved according to the invention by a transformer having the features of claim 1.

[0007] Advantageous embodiments of the invention are the subject of the dependent claims.

[0008] A transformer according to the invention comprises

[0009] - two low-voltage windings and

[0010] - a high-voltage winding, wherein

[0011] - the two low-voltage windings are wound interlocked. In a transformer according to the invention, the low-voltage winding is thus divided into two low-voltage windings compared to a conventional transformer. This allows the reactive power compensation by the wind turbine's converter to be advantageously increased compared to a transformer with only one low-voltage winding. Furthermore, the low-voltage windings are interlocked instead of being wound geometrically separately from each other, as is the case, for example, with so-called double-deck transformers. This results in the two low-voltage windings generating a leakage flux similar to that of a single winding at the same total current. This leads to very similar impedances and thus a very similar short-circuit current of the transformer with the two low-voltage windings as in a transformer with only one low-voltage winding.A transformer according to the invention with two low-voltage windings that are wound interlocked therefore enables, compared to a transformer with only one low-voltage winding, an increase in reactive power compensation with essentially unchanged short-circuit current of the transformer, relative to one low-voltage winding.

[0012] In one embodiment of the invention, the transformer has a transformer core, wherein the low-voltage windings and the high-voltage winding are wound around the transformer core. The transformer core amplifies and focuses the magnetic field of the transformer.

[0013] In a further embodiment of the invention, each low-voltage winding is a foil winding with a conductor foil wound around a winding axis, and the conductor foils of the two low-voltage windings are wound one on top of the other around the winding axis. The conductor foil of each low-voltage winding is, for example, an aluminum foil or a copper foil. The conductor foils of the two low-voltage windings are electrically insulated from each other. Due to the winding of the one on top of the other around the winding axis, the conductor foils follow each other alternately radially to the winding axis. The design of the conductor foils as aluminum foils or copper foils enables high electrical conductivity of the low-voltage windings.

[0014] In an alternative embodiment of the invention to the aforementioned configuration, each low-voltage winding has a conductor extending as a helix around a winding axis, and the helices formed by the conductors of the two low-voltage windings form a double helix. The conductor of each low-voltage winding is, for example, a twisted conductor. Furthermore, the conductors of the two low-voltage windings are, for example, made of copper or aluminum. The conductors of the two low-voltage windings thus each form a helix extending around the winding axis, with these two helices being offset from each other parallel to the winding axis. Twisted conductors have many individual conductors insulated from each other. This conductor configuration advantageously reduces eddy current losses in the conductors compared to solid conductors having the same cross-sectional area as the twisted conductors.Manufacturing the conductors from copper or aluminum enables high electrical conductivity of the low-voltage windings.

[0015] In a further embodiment of the invention, the high-voltage winding is wound around the low-voltage windings. For example, the high-voltage winding has a conductor that is a round conductor, a flat conductor, or a twisted conductor. This embodiment of the invention takes into account that the low-voltage winding typically has fewer turns and thicker conductors than the high-voltage winding and, due to the higher voltage, requires better insulation than the low-voltage windings. By winding the high-voltage winding around the low-voltage windings, the insulation of the high-voltage winding can be used to improve the overall insulation of the transformer. Furthermore, by arranging the high-voltage winding on the outside of the transformer, its size and weight can be reduced, and the heat dissipation efficiency of the transformer can be improved.

[0016] A wind turbine according to the invention has a transformer designed according to the invention.

[0017] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. These drawings show:

[0018] FIG 1 shows a first sectional view of a first embodiment of a transformer according to the invention,

[0019] FIG 2 shows a second sectional view of the transformer shown in Figure 1,

[0020] FIG 3 shows a side view of a second embodiment of a transformer according to the invention,

[0021] FIG 4 shows a block diagram of an embodiment of a wind turbine according to the invention.

[0022] Corresponding parts are marked with the same reference symbols in the figures.

[0023] Figure 1 (FIG 1) and Figure 2 (FIG 2) show a first embodiment of a transformer 1 according to the invention. The transformer 1 comprises two low-voltage windings 3, 5, a high-voltage winding 7, and a transformer core 9. Figure 1 shows the transformer 1 in a schematic first sectional view in a first sectional plane. Figure 2 shows the transformer 1 in a schematic second sectional view in a second sectional plane that is orthogonal to the sectional plane of Figure 1, with the high-voltage winding 7 not shown in Figure 2.

[0024] The low-voltage windings 3, 5 and the high-voltage winding 7 are wound around the transformer core 9. The transformer core 9 is formed from electrical steel sheets 11, which are electrically insulated from one another and arranged parallel to each other. A longitudinal axis of the transformer core 9 forms a winding axis 12, around which the low-voltage windings 3, 5 and the high-voltage winding 7 are wound.

[0025] Each low-voltage winding 3, 5 is a foil winding with a conductor foil 13, 15 wound around the winding axis 12. The conductor foils 13, 15 of the two low-voltage windings 3, 5 are wound around the winding axis 12, lying on top of each other and electrically insulated from each other. Each conductor foil 13, 15 is, for example, a copper foil or an aluminum foil.

[0026] The high-voltage winding 7 is wound around the low-voltage windings 3 and 5. The high-voltage winding 7 is therefore located at a greater distance from the winding axis 12 and from the transformer core 9 than the low-voltage windings 3 and 5. The high-voltage winding 7 has, for example, an electrical conductor, which may be a round conductor, a flat conductor, or a twisted conductor.

[0027] Figure 3 (FIG 3) shows a second embodiment of a transformer 1 according to the invention. The transformer 1 again comprises two low-voltage windings 3, 5, a high-voltage winding 7, and a transformer core 9, the high-voltage winding 7 not shown in Figure 3. The low-voltage windings 3, 5 and the high-voltage winding 7 are wound around the transformer core 9. The transformer core 9 is formed from electrical steel sheets 11, which are electrically insulated from one another and arranged parallel to each other. A longitudinal axis of the transformer core 9 forms a winding axis 12 around which the low-voltage windings 3, 5 and the high-voltage winding 7 are wound.

[0028] Each low-voltage winding 3, 5 has a conductor 17, 19 running as a helix around the winding axis 12. The helices formed by the conductors 17, 19 of the two low-voltage windings 3, 5 form a double helix. The conductor 17, 19 of each low-voltage winding 3, 5 is, for example, a twisted conductor, the individual conductors of which are, for example, each made of copper or aluminum.

[0029] The high-voltage winding 7, not shown in Figure 3, is wound around the low-voltage windings 3 and 5. The high-voltage winding 7 is therefore located at a greater distance from the winding axis 12 and from the transformer core 9 than the low-voltage windings 3 and 5. The high-voltage winding 7 has, for example, an electrical conductor, which may be a round conductor, a flat conductor, or a twisted conductor.

[0030] Figure 4 (FIG 4) shows a block diagram of an embodiment of a wind turbine 21 according to the invention. The wind turbine 21 comprises a generator 23, a converter 25, and a transformer 1 according to the invention. The generator 23 is configured to convert the rotations of a rotor of the generator 23, generated by wind power, into electrical energy. The converter 25 is configured to adapt the frequency of an electrical voltage generated by the generator 23 to a frequency of a power supply network into which the electrical energy generated by the wind turbine 21 is fed. The transformer 1 is configured to adapt the voltage to a nominal voltage of the power supply network. The transformer 1 is designed like a transformer described with reference to Figures 1 to 3.

[0031] Although the invention has been further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Claims

Patent claims 1. Transformer (1) , comprising - two low-voltage windings (3, 5) and - a high-voltage winding (7) , wherein - the two low-voltage windings (3, 5) are wound interlocked.

2. Transformer (1) according to claim 1 with a transformer core (9) wherein the low voltage windings (3, 5) and the high voltage winding (7) are wound around the transformer core (9).

3. Transformer (1) according to claim 1 or 2, wherein each low-voltage winding (3, 5) is a foil winding with a conductor foil (13, 15) wound around a winding axis (12) and the conductor foils (13, 15) of the two low-voltage windings (3, 5) are wound on top of each other around the winding axis (12).

4. Transformer (1) according to claim 3, wherein the conductor foil (13, 15) of each low voltage winding (3, 5) is an aluminum foil or a copper foil.

5. Transformer (1) according to claim 1 or 2, wherein each low-voltage winding (3, 5) has a conductor (17, 19) extending as a helix around a winding axis (12) and the helices formed by the conductors (17, 19) of the two low-voltage windings (3, 5) form a double helix.

6. Transformer (1) according to claim 5, wherein the conductor (17, 19) of each low-voltage winding (3, 5) is a twisted conductor.

7. Transformer (1) according to claim 5 or 6, wherein the conductors (17, 19) of the two low-voltage windings (3, 5) are made of copper or aluminium.

8. Transformer (1) according to one of the preceding claims, wherein the high voltage winding (7) is wound around the low voltage windings (3, 5).

9. Transformer (1) according to one of the preceding claims, wherein the high-voltage winding (7) has a conductor which is a round conductor or a flat conductor or a twisted conductor .

10. Wind power plant (21) with a transformer (1) designed according to one of the preceding claims .

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