EP2528072A1 - Transformer auxiliary winding - Google Patents

Abstract

The auxiliary winding (10) has a three winding modules (12,14,16), each comprising a winding segment (18,20,22) provided with respective tapings (24,26,28,30,32). A tap changer (34) is associated with the tapping (28) of the intermediate winding module (14). The terminals (40,42) of the intermediate winding module are formed by an external tapping and the output of the tap changer. The intermediate winding module is connected to the winding segments (18,22) of winding modules (12,16) with the two terminals which are electrically connected in series with contacts (44, 46).

Description

The invention relates to a transformer auxiliary winding, comprising first, second and third, winding module, each having at least a first, second or third respective taps winding segment, a connected to the taps of the second winding module tap changer, wherein the terminals of the second winding module by an external tap and the output of the tap changer are formed.

It is well known that power transformers, in particular oil transformers to increase their flexibility in the electrical power grid can be provided with so-called tap changers, whereby ultimately the transmission ratio of the transformer is within certain limits adaptable, for example in a range of 85% to 115% of the rated voltage. These are usually switchable under load selector switch, which depending on the given boundary conditions pick up one of, for example, 24 taps of an additional winding, which is usually connected electrically in series with a respective transformer main winding. It is also quite common to provide only a single winding, which then has in their rear area, for example in the last 20% of their winding, corresponding taps. The output of the tap changer then serves as the output of the series-connected main and auxiliary winding. Such tap changers are able to switch in particular due to their requirement under load current and the high demands on their isolation very complex and complex. When used in oil transformers due to its arrangement within the oil and flooding and the tap changer with oil, at least in terms of insulation costs a certain relief.

Such controllability is increasingly required even in so-called dry-type transformers. For example, at rated voltages between 6kV and 110kV, dry-type transformers have a rated power in the range of a few 100kVA up to several 10MVA. The rated output of dry-type transformers is thus typically below the rated output of oil transformers. Dry transformers are due to the non-existent oil or oil boiler compared to oil transformers low maintenance, but it is an increased effort to operate their isolation. This also applies accordingly to tap changers with which dry-type transformers can be equipped.

It proves disadvantageous, therefore, that the tap changer arrangements known from the field of oil transformers can not be transferred to dry-type transformers, or only at disproportionately high expense.

Based on this prior art, it is an object of the invention to provide a control option for transformer windings, in particular of dry-type transformers, which avoids the disadvantages mentioned. This object is achieved by a transformer additional winding of the type mentioned.

This is characterized in that the second winding module is connected at its two terminals with at least one winding segment of the first and third winding module and is electrically connected in series.

By a tripartite division of the additional winding into a first, second and third winding module, wherein a tap changer is provided only for the middle, namely the second winding module, the possible voltage swing, which is to be controlled by the tap changer, reduced in an advantageous manner. For example, with a typical number of 24 taps, 8 could each account for each of the three winding modules. Both the design effort and the insulation effort for the tap changer, which is typically not filled with oil and therefore very expensive, is thereby advantageously reduced.

Especially in the field of use of dry-type transformers, in network operation for control purposes, typically only a smaller voltage swing is required, which is to be covered by a tap changer. This is because of the lower percentage operational voltage fluctuations typically present at the lower voltage levels of dry type transformers, which would be offset by a control device such as a tap changer. However, a larger control range known from oil transformers, covering, for example, a range of 80% to 120% of the nominal voltage of the dry-type transformer, is necessary when balancing long-term and network-related voltage changes, for example, when planned, generally reducing the voltage in some power supply by a few Percent increase. In this case, the tap changer would operationally operate in the upper range of selectable stages after the voltage boost, whereas the lower then range would remain unused.

The invention is therefore based on the basic idea to provide a tap changer, which covers the operationally occurring voltage fluctuation band control technology and set long-term voltage fluctuations by means of the number of series winding segments of the first and third winding modules. In the event that a small number of first and third winding segments are connected in series, the controllable output voltage would accordingly be in a lower voltage range, with a correspondingly high number of series-connected first and third winding segments accordingly in an upper region. Long-term fluctuations of the voltage band are thus compensated in an advantageous manner over the first and third winding segments.

According to the invention, it is proposed to carry out such an adaptation of the additional winding to long-term voltage changes in the de-energized state and possibly also manually, because then the interconnection of the winding segments of the first and third winding module is to be carried out with less effort, in the simplest case with a screw or other attachment of a connection cable or the like between the corresponding taps. These are then to be provided with appropriate fasteners for this case.

The inherently symmetrical design with three winding modules, of which the middle is provided with a tap changer, causes the shortening of the stroke of the tap changer does not adversely affect the short-circuit behavior of the transformer or the transformer additional winding, which would also be unbalanced in this case. In contrast to the obvious variant with only two series-connected winding modules, namely a first without tap-changer and a second tap-changer, thus an improved operating behavior is effected. In addition, in the arrangement with three winding modules results in a more uniform change in the short-circuit impedance of the transformer in the different tapped positions.

According to a preferred embodiment of the transformer additional winding, the second winding module has a plurality of winding segments connected electrically in series. The number of winding segments and their respective number of turns determine the control band of the voltage, which can be realized by means of the tap changer. Depending on the requirements in the electrical network, for example, a maximum of eight, but in some cases even two or three winding segments for a second winding module may be sufficient to realize the desired control characteristic. The voltage swing, which is ideally achievable with a respective winding segment, for example, in Beeich of 1% - 2% of the rated voltage, so that summarily for all winding segments, for example, a total stroke of +/- 5% results, this being very dependent on the respective boundary conditions. The term rated voltage in this context refers to the rated voltage of a transformer main winding in series with the additional winding and is for example 1 0 kV or 110 kV.

According to a further preferred embodiment of the transformer additional winding according to the invention, the first and the third winding module has a plurality of electrically connected in series first and third winding segments. The number of winding segments of the first and third winding module determines together with their respective number of turns the maximum voltage swing at which the controllable voltage band of the second winding module with tap changer for long-term voltage changes is displaceable. Since it is ultimately an offset setting, it makes sense to limit the number to fewer winding segments with a correspondingly higher number of turns, so that, for example, four winding segments per winding module result, for example, a stroke of 2.5% each Rated voltage.

According to a further variant of the invention, the necessary for a series connection of the first and / or the third winding module contacting the respective taps by means of a mechanically detachable conductor and / or cable connection is realized. A change in the interconnection of the first and third winding module is typically only necessary in the case of long-term changes in the network conditions, for example a slight increase in the rated voltage. This can be realized particularly easily during a regular maintenance cycle, for example by manually connecting corresponding cables or other electrical connections to the respective desired taps. For this example, clamping or screw connections are conceivable.

According to a further embodiment of the transformer additional winding according to the invention at least a portion of the taps of the first and / or third winding module is connected to the inputs of a respective selector switch, so that the number of electrically connected to the second winding module in series first or third winding segments is thus defined. This variant is particularly advantageous if short-term or medium-term changes in the grid voltage can occur, so that the offset of the second winding module is correspondingly adapted frequently. Such a selector switch is typically to be de-energized and can be switched manually or with a drive. By a circuit only in the de-energized state of the selector switch can be configured according to simple and compact. In this case, the taps of the first and third winding module, for example, with appropriate sliding contacts equip, over which a movable pickup is feasible.

In a particularly preferred manner, the number of series winding segments of the first winding module and the number of series winding segments of the third winding module are approximately the same, ideally identical. By a similar number of winding segments is connected on both sides of the second winding module, the symmetry of the entire additional winding is favored accordingly and improves the performance. Ultimately, however, not the number of actively connected in series winding segments but the number of actively connected in series turns of the winding is crucial, since it is certainly provided according to the invention to provide winding segments with different numbers of turns within one and the same winding module. As a result, for example, the flexibility of the voltage regulation would be further increased in an advantageous manner.

In a likewise preferred manner, the contacting of the first and / or third winding module to the respective connection with the terminals of the second winding module takes place at the respective outer tap adjacent to the second winding module. The taps are arranged on the winding surface mostly along a path, wherein the first and the last tap each form an external tap. The arrangement of the taps on the winding surface usually correlates within certain limits with the arrangement of the winding segments in the winding. If the respectively adjacent second winding module geometrically adjacent tap for the electrical series circuit is used, so unnecessary open winding segments are ultimately avoided with increased potential between active winding segments. This advantageously increases the reliability.

According to a further preferred embodiment, the first and the second winding module are formed by a common winding module with a corresponding number of taps. In this way, a contacting of both winding modules is not necessary, since these are not galvanically isolated anyway. This simplifies the production of such an additional winding. In the case of a common winding module, it is generally also to be assumed that first and second winding segments comprise a different number of windings. Also avoided here is the arrangement of open winding segments between active winding segments.

The object according to the invention is also achieved by a transformer winding comprising a transformer additional winding according to the invention and a transformer main winding electrically connected in series therewith. The transformer main winding here serves to introduce the majority of the voltage induced in the overall winding, for example 85%, while the additional winding contributes, for example, a maximum of 30% to the induced voltage, of which, for example, 10% each relate to first, second and third winding module. But it is also quite possible a division of 12%, 6% and 12%. The aforementioned advantages of an additional winding according to the invention also extend in a comparable manner to a transformer winding according to the invention.

This applies in the same way for a corresponding three-phase transformer winding and a dry-type transformer with a transformer winding according to the invention.

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

eine exemplarische erste Transformatorzusatzwicklung

Fig. 2

eine exemplarische zweite Transformatorzusatzwicklung sowie

Fig. 3

ein exemplarisches erstes und zweites Wicklungsmodul in Schnittansicht.

Show it:

Fig. 1

an exemplary first transformer addition winding

Fig. 2

an exemplary second transformer additional winding as well

Fig. 3

an exemplary first and second winding module in a sectional view.

Fig. 1 shows an exemplary first transformer accessory winding 10 having first 12, second 14, and third 16 winding modules. The winding modules are indeed as galvanically isolated, but are typically considered to be arranged on one and the same winding body about a common axis of rotation around. The first winding module 12 has three first winding segments 18, which are galvanically connected in series and are guided for contacting with their respective terminals as taps 24, 26 to the surface of the winding body not explicitly shown. Analogous to the first winding module 12, a third winding module 16 is constructed, which has three third winding segments 22 connected in series, the terminals of which are guided as taps 30, 32 on the surface of the winding body, not shown.

A second winding module 14 comprises five exemplary electrically connected in series second winding segments 20, whose terminals are guided as taps 28 to the surface of the winding body, not shown. The taps 28 of the second winding module 14 are electrically connected to the inputs of a tap changer 34, which selectively connects one of the taps 28 electrically to its output. This is done by means of a movable in the direction of arrow 38 contact 36, which produces a respective electrical connection with connected to the taps sliding contacts. The terminals 40, 42 of the second winding module 14 are formed by an external tap and the output of a tap changer 34. By means of the contacts 44, 46, the terminals 40, 42 are galvanically connected to the respective outer and adjacent to the second winding module 14 taps 26, 32 of the first 12 and third 16 winding module. The contacts 44, 46 are for example insulated cables or else copper rods or other conductors. Thus, the winding modules 12, 14, 16 are electrically connected in series.

The taps 24, 28 of the first winding module 12 are provided with corresponding contacting devices, so that by means of a contact 52 optionally an electrical connection to a first terminal 48 of the transformer additional winding can be produced. This can be done either by means of a manually arranged and to be fastened cable or conductor connection, or even by means of a selector switch, which electrically fulfills the same function. This is preferably designed such that it only switches in the de-energized state, so as to reduce its design complexity. In an analogous way, the taps 30, 32 of the third winding module 22 by means of a contact with a second terminal 50 of the transformer additional winding connectable. A connection of the transformer additional winding thus takes place via its two terminals 48, 50.

Fig. 2 shows an exemplary second transformer auxiliary winding 60. This corresponds in its essential components of the first transformer winding 10 from Fig. 1 , However, in this example, the first and second winding modules are combined in a common winding module 62. However, this is galvanically isolated from a third winding module 64. This separation is necessary in order to be able to introduce the output of the tap changer into the third winding module, and to avoid a short circuit with the non-active second winding segments in the rear region (shown on the right in FIG. 1) of the common winding module 62.

Fig. 3 an exemplary first and second winding module in a sectional view 70. This sectional view comes close to the real structure of a transformer additional winding according to the invention relatively close, as here the layer-wound structure around a winding axis 90 is shown. An exemplary first winding module is indicated by the reference numeral 72 and a second exemplary winding module by the reference numeral 74. The solid lines with which the winding modules 72, 74 are illustrated, however, do not describe an electrical conductor, but rather the winding scheme of one wound around the winding axis 90 Ladder, so the cross-sectional profile of juxtaposed conductor sections. The conductor is wound in a plurality of winding layers 80, 82, 84, 86, 88 meandering from the radially inner region to the radially outer region. The first winding module 72, which would also essentially correspond to a third winding module, has three exemplary taps 76. The second winding module 74 has nine exemplary taps 78, which are then to be connected to a tap changer, not shown. The number of windings of the winding segments connected between adjacent taps is significantly higher in the case of the first winding module 72 than in the second winding module 74, since this only serves to set the offset of the voltage control band of the second winding module, which typically has to be less finely graduated.

LIST OF REFERENCE NUMBERS

10

exemplary first transformer addition winding

12

first winding module

14

second winding module

16

third winding module

18

Winding segments of the first winding module

20

Winding segments of the second winding module

22

Winding segments of the third winding module

24

Taps of the first winding module

26

external second winding module adjacent tap

28

Taps of the second winding module

30

Taps of the third winding module

32

external second winding module adjacent tap

34

step switch

36

moving contact

38

Direction of movement of the contact

40

first connection second winding module

42

second connection second winding module

44

Contacting between first and second winding module

46

Contact between second and third winding module

48

first connection of the transformer auxiliary winding

50

second connection of the transformer auxiliary winding

52

Contacting of the first terminal of the transformer auxiliary winding

54

Contacting of the second terminal of the transformer auxiliary winding

60

exemplary second transformer addition winding

62

common winding module

64

third winding module

70

exemplary first and second winding module in a sectional view

72

exemplary first winding module

74

exemplary second winding module

76

Taps of first winding module

78

Taps of second winding module

80

first winding layer of the second winding module

82

second winding layer of the second winding module

84

third winding layer of the second winding module

86

fourth winding layer of the second winding module

88

fifth winding layer of second winding module

90

winding axis

Claims (11)

A transformer accessory winding (10, 60) comprising first (12, 72), second (14, 74) and third (16, 64) winding modules each having at least a first (18), second (20) and third (22) respective taps (24, 26, 28, 30, 32, 76, 78) having winding segment (18, 20, 22), one connected to the taps (28, 76) of the second winding module (14, 78) tap changer (34), wherein the Connections (40, 42) of the second winding module (14, 78) by an external tap and the output of the tap changer (34) are formed, characterized in that
the second winding module (14, 78) is connected at its two terminals (40, 42) to at least one winding segment (18, 22) of the first (12, 72) and third (16, 64) winding module and electrically connected in series (44, 46). Transformer additional winding according to claim 1, characterized in that the second winding module (14, 78) has a plurality of electrically connected in series winding segments (20). Transformer additional winding according to claim 1 or 2, characterized in that the first (12, 72) and the third (16, 64) winding module having a plurality of electrically connected in series winding segments (18 or 22). Transformer additional winding according to one of the preceding claims, characterized in that the necessary for a series connection of the first and / or the third winding module contacting (44, 46, 52, 54) of the respective taps (24, 26, 28, 30, 32, 76, 78) is realized by means of a mechanically detachable conductor and / or cable connection. Transformer additional winding according to one of the preceding claims, characterized in that at least a part of the taps (24, 26, 30, 32, 76) the first (12, 72) and / or third (16, 64) winding module are connected to the inputs of a respective selector switch, so that the number of winding segments (18, 22) connected in series electrically to the second winding module (14, 74) so that is definable. Transformer additional winding according to one of the preceding claims, characterized in that the number of series-connected winding segments (18) of the first winding module (12, 72) and the number of series-connected winding segments (22) of the third winding module (16, 64) in approximately are the same, preferably identical. Transformer additional winding according to one of the preceding claims, characterized in that the contacting (44, 46) of the first (12, 72) and / or third (16, 64) winding module for the respective connection to the terminals of the second winding module (14, 74) the respective outer, the second winding module (14, 74) adjacent tap (26, 32) takes place. Transformer additional winding claim 7, characterized in that the first (12, 72) and the second (14, 74) winding module by a common winding module (62) is formed with a corresponding number of taps. A transformer winding comprising a transformer auxiliary winding (10, 60) according to any one of claims 1 to 8 and optionally a transformer main winding electrically connected in series therewith. Transformer winding according to claim 9, characterized in that it is designed in three phases. A dry type transformer comprising a transformer core and a transformer winding according to one of claims 9 or 10.

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