EP2866235B1 - High voltage transformer - Google Patents

Description

The invention relates to a high-voltage transformer according to the preamble of patent claim 1.

It is well known that in high-voltage transformers, for example, in the rated voltage range of 6 kV, 10kV, 30kV, 60kV, 110kV and above, measures for mutual isolation of adjacent coils are to be made in order to avoid electrical breakdown. A simple possibility is to increase the distances between live components accordingly, but this also disadvantageously increases the size of the high-voltage transformer. This applies in particular to dry-type transformers in which insulation is provided only by the medium air.

In order to reduce the distance between adjacent coils and thus the size of a transformer, it is common in the art to arrange so-called intermediate barriers between adjacent coils. These are essentially plates made of an insulating material, which are arranged between the coils and which allow by a correspondingly extended discharge path along the surface thereof to arrange the respective coils with a correspondingly smaller distance from each other.

The US 4,173,747 A discloses a transformer coil having a fully encircling fully encircling flexible barrier structure with strip-like spacers.

The WO 2006/069 590 A1 discloses an electrical induction device for high voltage applications, each having a hollow cylindrical inner and outer winding arranged around a leg and interleaved, in the radial gap of which a complete barrier structure is arranged.

The EP 2 472 533 A1 discloses a transformer winding with two radially interleaved hollow cylindrical winding parts, in the radial gap a full-scale barrier structure is provided.

The US 3,142,029 A discloses coils surrounded by metallic shields axially spaced by annular spacers.

It proves to be disadvantageous that space-related conflicts with, for example, the connections of the coils can arise due to the insulation technology required width of the barrier walls, for example with triangular derivatives. Such connections are then lead around the barriers in a complex manner.

Based on this prior art, it is an object of the invention to provide a high-voltage transformer, which avoids a separate arranged between adjacent coils barrier structure.

This object is achieved by a high-voltage transformer according to claim 1.

The basic idea of the invention is to integrate a barrier directly into the insulation technology critical surface areas of adjacent coils. These are in particular those surface areas of adjacent coils which face each other, wherein within these surface areas at the smallest mutual distance there is also the highest risk of breakdown. A respective barrier structure typically includes the entire axial length of a coil, but may also be somewhat shortened or lengthened as needed. Depending on the type of transformer core, different opposite surface areas result. In the case of three coils arranged on an E-core, two barrier structures are provided, for example for the middle coil, arranged radially on the outside, wherein a barrier structure arranged radially on the outside is required for each of the two outer coils.

In the case of a triangular transformer core, each barrier would have two barrier structures offset by 60 ° from each other, which should be realized by an overarching barrier structure.

Accordingly, in a single-phase transformer having a 2-leg core, each of the two coils in the region to the adjacent coil would be provided with a barrier structure.

According to a preferred embodiment of the high-voltage transformer according to the invention, the barrier structures are designed such that the voltage difference occurring between the electrical windings of the adjacent coils during operation is held without an additional barrier wall arranged between the coils.

An integrated barrier structure advantageously reduces the field strength loading prevailing between the coils in such a way that no further intermediate barrier is necessary any more. For example, a barrier structure can be thought of as a lens-like attachment to the radially outer surface of a coil. Ideally, a barrier structure has already been integrated into the coil during the production process, similar to the cooling channels known to those skilled in the art, which, however, are not arranged on the surface of the coil, but between radially adjacent coil segments.

By correspondingly mechanically fixed integration into the surfaces of the respective coils, the mechanical stability of a respective transformer is advantageously increased because a mechanically labile construction of one or more barrier plates arranged between the coils has been dispensed with. In an equally advantageous manner, therefore, in a transformer according to the invention, all the connections of the coils can be guided without geometric impairments.

The barrier structures comprise axially extending strips which carry a barrier wall arranged radially above them. Such a concept is characterized by a simple manufacturing method and a high mechanical stability. As a sufficiently stable material for the strips, for example, offers a glass fiber composite material.

According to a further embodiment variant of the high-voltage transformer according to the invention, the barrier wall is at least partially made of one wrapped band-like material. A belt-like material, such as a resin impregnated glass fiber reinforced fiber roving, which is heated after completion of the winding process of a coil and thereafter forms a hardened structure, is known in winding coils of high voltage transformers for isolation and stabilization purposes. According to the invention, it is therefore provided in a variant to fix the radially outer barrier structure with such a material or even to wrap it at least partially. Advantageously, this achieves both high mechanical strength and good insulation capability.

According to another variant of the invention, the barrier wall at least partially consists of a prefabricated cylindrical element, for example an insulating half-shell. Such cylinder or shell elements can be easily integrated during the winding process of a coil and have proven themselves, for example, in the integration of cooling channels.

There are at least partially provided a plurality of radially adjacent layers of strips and barrier walls. As a result, for example, both the mechanical stability of the barrier structure and its isolation capability are advantageously increased.

According to a further variant of the invention, the barrier structure of at least one coil is formed over its entire circumference. A 360 ° circulating barrier structure is characterized in particular by a simpler manufacturing, on the other hand, a slightly increased space is needed. If this installation space is present at a respective transformer, in this way the production of the coils can be simplified in an advantageous manner, and it is also no longer to pay attention to an alignment of the barrier structure relative to the transformer core.

The barrier structure of at least one coil is not formed over its entire circumference, wherein the cross section of the barrier structure is stepped-like at its two outer ends. This is a variant which can be realized in a particularly simple manner, for example by means of a plurality of strips with radially attached shell element, wherein the two outer Steps are formed by a respective side wall of the respective outer strips.

According to the invention, the barrier structure of at least one coil is not formed over its entire circumference, wherein the cross section of the barrier structure at its two outer ends merges flat into the surface of the coil. According to the invention, this is particularly suitable for at least partially wound barrier walls, wherein a respective insulating strip (18, 20, 22, 52, 72) then runs approximately tangentially between the upper edge of a respective outer strip and the surface of the respective coil. By avoiding a step, the most compact possible surface structure is formed.

According to a further variant of the invention, at least one of the barrier structures forms cavities extending over their entire axial length, which cavities act as cooling channels. Namely, a barrier structure is very similar to the structure of cooling channels arranged between radially adjacent coil segments, for example in the scattering channel. In this case, the chimney effect is advantageously utilized. According to a further variant of the invention, at least one of the barrier structures projects beyond at least one axial end of the respective coil. This is useful, for example, for controlling the air conditions at the ends of the respective cooling channels in order to increase their cooling effect.

Further advantageous embodiment possibilities can be found in the further dependent claims.

Reference to the embodiments illustrated in the drawings, the invention, further embodiments and other advantages will be described in detail.

• Fig. 1 einen exemplarischen Hochspannungstransformator nützlich für das Verständnis der Erfindung.
• Fig. 2 einen exemplarischen Hochspannungstransformator gemäß dem Stand der Technik.
• Fig. 3 eine erste exemplarische hohlzylindrische Spule mit Barrierenstruktur gemäß der Erfindung.
• Fig. 4 eine zweite exemplarische hohlzylindrische Spule mit Barrierenstruktur nützlich für das Verständnis der Erfindung.
• Fig. 1 zeigt einen exemplarischen Hochspannungstransformator in einer Schnittdraufsicht 10. Um drei in einer gemeinsamen Ebene angeordnete Kernschenkel 12, 14, 16 eines Transformatorkerns sind jeweils eine hohlzylindrische Spule 18, 20, 22 angeordnet. Jede Spule 18, 20, 22 weist eine radial innen liegende Unterspannungswicklung und eine radial außen liegende Oberspannungswicklung auf. In die durch die Pfeile 36 und 38 gekennzeichneten gegeneinander zugewandten Oberflächen der Spulen 18, 20, 22 sind linsenähnliche Barrierenstrukturen integriert, welche jeweils durch Leisten 26, 30, 34 und radial darüber liegende Barrierenwandungen 24, 28, 32 gebildet sind. Die Barrierenwandungen sind in diesem Fall vorgefertigte Schalenelemente, welche mittels eines gewickelten Faserrovings auf der Oberfläche der Spulen 18, 20, 22 fixiert sind.
• Fig. 2 zeigt im Gegensatz zur Fig. 1 einen exemplarischen Hochspannungstransformator gemäß dem Stand der Technik, welcher zwischen benachbarten Spulen jeweilige Barrierenwandungen 42, 44 aufweist, welche erfindungsgemäß zu vermeiden sind.
• Fig. 3 zeigt eine erste exemplarische hohlzylindrische Spule mit Barrierenstruktur in einer Darstellung 50. In einem Teilbereich der radial äußeren Oberfläche einer Spule 52 ist eine Barrierenstruktur 54 integriert. Diese weist radial übereinander angeordnete Barrierenwandungen 56, 58 auf, welche jeweils von axial verlaufenden Leisten abgestützt sind. Die Zwischenräume zwischen Leisten und Barrierenwandungen sind als kanalähnliche Hohlräume 60, 62 ausgebildet und werden als Kühlkanäle genutzt. Die Seitenflächen der äußeren Barrierenwandungen 56, 58 bilden einen stufenähnlichen seitlichen Abschluss der Barrierenstruktur 54.
• Fig. 4 zeigt eine zweite exemplarische hohlzylindrische Spule mit Barrierenstruktur in einer Darstellung 70. An einem Teilbereich der Außenfläche einer hohlzylindrischen Spule 72 ist über einen Winkelbereich von etwa 90° eine Barrierenstruktur 74 integriert, deren Barrierewandung gewickelt ist, so dass diese flach in die Oberfläche der Spule 72 übergeht.

Show it:

• Fig. 1 an exemplary high voltage transformer useful for understanding the invention.
• Fig. 2 an exemplary high-voltage transformer according to the prior art.
• Fig. 3 a first exemplary hollow cylindrical coil with barrier structure according to the invention.
• Fig. 4 a second exemplary hollow cylindrical coil with barrier structure useful for understanding the invention.
• Fig. 1 shows an exemplary high-voltage transformer in a sectional top view 10. Around three arranged in a common plane core legs 12, 14, 16 of a transformer core each have a hollow cylindrical coil 18, 20, 22 are arranged. Each coil 18, 20, 22 has a radially inwardly located lower voltage winding and a radially outer high-voltage winding. In the mutually facing surfaces of the coils 18, 20, 22 marked by the arrows 36 and 38, lens-like barrier structures are integrated, which are respectively formed by strips 26, 30, 34 and barrier walls 24, 28, 32 lying radially above them. The barrier walls in this case are prefabricated shell elements, which are fixed on the surface of the coils 18, 20, 22 by means of a wound fiber roving.
• Fig. 2 shows in contrast to Fig. 1 an exemplary high-voltage transformer according to the prior art, which has between adjacent coils respective barrier walls 42, 44, which are to be avoided according to the invention.
• Fig. 3 shows a first exemplary hollow cylindrical coil with barrier structure in a representation 50. In a portion of the radially outer surface of a coil 52, a barrier structure 54 is integrated. This has radially superimposed barrier walls 56, 58, which are each supported by axially extending strips. The spaces between strips and barrier walls are formed as channel-like cavities 60, 62 and are used as cooling channels. The side surfaces of the outer barrier walls 56, 58 form a step-like lateral termination of the barrier structure 54.
• Fig. 4 shows a second exemplary hollow cylindrical coil with barrier structure in a representation 70. At a portion of the outer surface of a hollow cylindrical coil 72 over a angular range of about 90 °, a barrier structure 74 is integrated, the barrier wall is wound so that it flat in the surface of the coil 72nd passes.

LIST OF REFERENCE NUMBERS

10

exemplary high-voltage transformer according to the invention

12

first core leg

14

second core leg

16

third core leg

18

first hollow cylindrical coil of high voltage transformer

20

second hollow cylindrical coil of high voltage transformer

22

third hollow cylindrical coil of high voltage transformer

24

Barrier wall of barrier structure of first coil

26

Bar of barrier structure from first coil

28

Barrier wall of barrier structure of second coil

30

Bar of barrier structure from second coil

32

Barrier wall of barrier structure of third coil

34

Bar of barrier structure of third coil

36

first surfaces facing each other

38

second facing surfaces

40

Exemplary high-voltage transformer according to the prior art

42

Barrierenwandungen

44

Barrierenwandungen

50

first exemplary hollow cylindrical coil with barrier structure

52

first exemplary hollow cylindrical coil

54

Barrier structure of first exemplary coil

56

first barrier wall of barrier structure

58

second barrier wall of barrier structure

60

first cavity (used as cooling channel)

62

second cavity (used as cooling channel)

70

second exemplary hollow cylindrical coil with barrier structure

72

second exemplary hollow cylindrical coil

74

Barrier structure of second exemplary coil

Claims (6)

1. High-voltage transformer (10) comprising a transformer core having at least two core limbs (12, 14, 16) which are axially parallel and on which in each case a hollow-cylindrical coil (18, 20, 22, 52, 72) having in each case at least one electrical winding is arranged, wherein, at least in partial regions of mutually facing surfaces (36, 38) of adjacently arranged coils (18, 20, 22, 52, 72), the respective surface regions of the coils have a respective electrically isolating barrier structure (54, 74) which is integrated radially on the outside and wherein the barrier structure (54, 74) of at least one coil (18, 20, 22, 52, 72) is not formed over the entire circumference thereof, characterized in that the barrier structures (54, 74) comprise slats (26, 30, 34) which run axially and which support a barrier wall (24, 28, 32, 56, 58) which is arranged radially opposite, wherein, at least in regions, a plurality of radially adjacent layers of slats (26, 30, 34) and barrier walls (24, 28, 32, 56, 58) are provided and wherein the cross section of the barrier structure (54, 74) at the two outer ends thereof transitions in a flat manner into the surface of the coil (18, 20, 22, 52, 72) or is marked in a step-like manner at the two outer ends thereof, wherein the two outer steps are formed by a respective side wall of the respectively outer slats.
2. High-voltage transformer according to Claim 1, characterized in that the barrier wall (24, 28, 32, 56, 58) is at least partially wound from a ribbon-like material.
3. High-voltage transformer according to Claim 1 or 2, characterized in that the barrier wall (24, 28, 32, 56, 58) at least partially consists of a prefabricated cylinder element.
4. High-voltage transformer according to any of the preceding claims, characterized in that the barrier structure (54, 74) of at least one coil (18, 20, 22, 52, 72) is formed over the entire circumference thereof.
5. High-voltage transformer according to any of the preceding claims, characterized in that cavities (60, 62), which act as cooling ducts, are formed through at least one of the barrier structures (54, 74), said cavities extending over the entire axial length of the barrier structures.
6. High-voltage transformer according to any of the preceding claims, characterized in that at least one of the barrier structures (54, 74) projects beyond at least one axial end of the respective coil (18, 20, 22, 52, 72) .

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