AU2013337129B2

AU2013337129B2 - Electric generator for producing electricity in power plants

Info

Publication number: AU2013337129B2
Application number: AU2013337129A
Authority: AU
Inventors: Stefan Vosskuhler; Thorsten Wasmuth
Original assignee: Sensoplan GmbH
Current assignee: Sensoplan GmbH
Priority date: 2012-10-26
Filing date: 2013-10-15
Publication date: 2017-09-14
Anticipated expiration: 2033-10-15
Also published as: DE102012021114B4; ZA201503634B; AU2013337129A1; EP2912756A2; DE102012021114A1; WO2014063673A2; WO2014063673A3

Abstract

An electric generator for producing electricity in power plants has an excitation winding (3) on the shaft (1). The turns (4) of the excitation winding (3) are each formed of two half-turns (4') which are soldered together at both ends thereof.

Description

1 2013337129 31 Μ 2017

Electric generator for producing electricity in power plants

The invention relates to an electric generator for 5 producing electricity in power plants as claimed in the preamble of claim 1; embodiments of the invention further relate to a method for producing a conductor for the rotor of an electric generator; other embodiments of the invention finally relate to a method 10 for improving the conductors for the rotor of an electric generator.

Any discussion of the prior art throughout the specification should in no way be considered as an 15 admission that such prior art is widely known or forms part of common general knowledge in the field.

Electric generators for producing electricity in power plants have a rotor. This rotor initially has a shaft. 20 The two poles of the rotor are arranged on this shaft. Said poles each have a winding comprising a plurality of coils, wherein each coil in turn consists of a plurality of turns. These turns are formed by electrical conductors which are composed of copper and 25 are embedded in slots. In this case, the conductors extend between the two winding heads parallel to the shaft. In addition to these axial conductors, the tangential conductors, which are curved in a circular manner in which the axis of the shaft defines the 30 center point of a circle, are also provided at the ends .

During operation of the generator, an electric current flows through the conductors. These electric currents 35 are comparatively high and cause a correspondingly high level of heating. This reduces the service life and 2 2013337129 31 Μ 2017 also the operational performance. The conductors in the rotor are cooled for this reason.

Specifically, the field winding of generator rotors is 5 cooled with air or hydrogen in order to dissipate the lost heat which is produced by the field current and to prevent overheating of the insulation components. In the process, there are 3 important cooling principles which are usually used (in this case, the following 10 variants are in order of increasing effectiveness of the cooling and therefore the output densities of the generator which can be achieved):

Variant 1 is indirect cooling due to the cooling gas 15 flowing past the narrow sides of the conductors of the winding.

Variant 2 is direct cooling with the cooling gas flowing transversely through the conductor through 20 corresponding radial bores.

Variant 3 is likewise direct cooling with the cooling gas flowing longitudinally through the conductor. 25 Solid copper profiles are used for the conductors of the turns for variants 1 and 2. In this case, the conductors are additionally provided with radial bores for the cooling gas to flow through for variant 2. Single or double hollow profiles are usually used for 30 variant 3.

Rotor windings are preferably cooled either in accordance with variant 1 or in accordance with variant 2 or in accordance with a combination of variants 1 and 35 2. As an alternative, the rotor winding is also cooled in accordance with variant 3. This allows the use of only one profile type (solid or hollow conductor) and 2013337129 31 Μ 2017 3 therefore a minimum number of solder points in the winding since different profile types do not have to be connected to one another. A minimum number of solder points is advantageous since solder points constitute a 5 mechanical weak point.

However, generator rotors in which the straight, axial part of the conductor of a turn is designed as a solid profile and is predominantly cooled in accordance with 10 variant 1 or in accordance with variant 2 or in accordance with a combination of these variants are also available. The bent, tangential part of the conductor however is in the form of a hollow conductor, specifically using cooling in accordance with variant 15 3. In this case, the two profile types can also have different widths. However, this concept requires a total of 4 solder points per turn, specifically in each case 2 on the drive and the non-drive side of the rotor in order to connect in each case 2 hollow and solid 20 profiles to one another to form a turn. On account of their geometric position at the transition between axial and tangential conductors, these solder points are subject to very high mechanical and thermally induced forces and therefore form a particular weak 25 point.

Taking this as a basis, an embodiment of the invention is based on the object of providing an electric generator for producing electricity in power plants, in 30 which electric generator the conductors of the turns have as few solder points as possible with a maximum cooling capacity.

The technical solution is characterized by the features 35 of claim 1. 2013337129 31 Μ 2017 35 4

As a result, an electric generator for producing electricity in power plants is provided, in which electric generator the conductors of the turns have only 2 solder points. The cooling capacity of the 5 cooling gas is not restricted in any way in the process. The basic idea is that the turns or conductors consist of 2 half-turns or 2 half-conductors which are both mechanically and electrically connected to one another at their ends. The generator according to the 10 invention therefore has a generator rotor winding which can be cooled in accordance with the above-described variants 1 and/or 2 in combination with variant 3. In this case, 2 different conductor profiles are used per turn, but it is possible for said conductor profiles to 15 be produced from only one type of conductor profile. Since the turns are designed as half-turns, the number of solder points per winding can - as stated - be reduced to 2 solder points. In this case, these two solder points can be placed in position with a low 20 level of loading.

According to the development in claim 2, the ends of the two half-turns or the two half-conductors are preferably soldered to one another. This method of 25 mechanical and electrical connection has proven to be effective .

According to the development in claim 3, it is proposed that the two half-turns are of C-shaped form. In this 30 case, the interface with the solder points of said half-turns is situated between the two C-shaped halfturns in the longitudinal center plane of the rotor, that is to say at the apex of the circular tangential conductors. It goes without saying that it is feasible to place the solder points in other positions too. 5 2013337129 31 Μ 2017

According to the development in claim 4, the conductors of the turns have cooling channels which run in the transverse direction. This relates to the axial conductors in which the cooling channels extend in the 5 radial direction in relation to the shaft as bores. This flow of cooling gas transversely through the conductor in these axial conductor sections provides an optimum cooling performance. Furthermore, the bores for the cooling gas to flow through can easily be made in 10 the conductors.

The development as claimed in claim 5 proposes one option for direct cooling with the cooling gas flowing longitudinally through the conductor. These cooling 15 channels are intended for the circular tangential conductor . A preferred structural solution for this is proposed by the development as claimed in claim 6. In this case, 20 the basic idea is that the conductor starts with a solid profile. First, channels which are open at the top, for example in a U-shape, are milled into this solid profile. One or more of these channels can be provided in this case. These channels are closed at the 25 top by applying a so-called intermediate insulation to the conductors, so that cooling gas flows longitudinally through the conductor as a result. This is similar to the case with the previous hollow conductor. As a result, a cooling channel which runs in 30 the longitudinal direction of the conductor is provided in a technically extremely simple manner without having to use a special hollow profile. The reason for this is that the cooling channels are produced by milling material out of the flat top face of the conductor. 35

As a further technical solution, claim 7 proposes a method for producing a conductor for the rotor of an 6 2013337129 31 Μ 2017 electric generator for producing electricity in power plants .

The core idea is that the conductor starts with a solid 5 profile which, in the initial state, has the same cross-sectional profile over the entire length.

Therefore, the conductor starts with a solid profile with the length of half a turn and with the cross-sectional dimensions of the largest profile cross-10 section required. This is the relatively wide profile of the profile usually used previously (usually the hollow profile). According to the invention, the width of the solid profile is appropriately reduced in that region in which a relatively narrow profile is required 15 (the previous relatively narrow profile) by machining. Therefore, adjustments to achieve the desired profile or cross-sectional profile are made by removing material. According to the invention, the conductor is now reshaped by suitable methods to form a 90° arc at 20 the point at which the solder connection between the two different profiles previously formed a right angle. Cooling in accordance with the above-described variant 3 in the region of the tangential conductor is - as stated - realized by milling one or more channels, 25 which are open at the top, along the solid conductor. As a result, a tangential conductor virtually in the form of a hollow conductor which starts out as a standard solid conductor profile is produced overall. 30 As a further technical solution, claim 8 proposes a 35 method for improving the conductors for the rotor of an electric generator for producing electricity in power plants. Therefore, it is possible to improve existing electric generators for producing electricity in power plants, specifically to improve the conductors of said electric generators, by the old, above-described 7 2013337129 31 Μ 2017 conductors being replaced by conductors or turns according to the invention.

According to a first aspect of the present invention 5 there is provided an electric generator for producing electricity in power plants, comprising a rotor which has a shaft, and also comprising a field winding which is arranged on the shaft, 10 wherein the field winding consists of a plurality of turns, and the turns each consist of a plurality of conductors, wherein the turns each consist of two halfturns which are electrically and mechanically connected to one another at their two corresponding free ends; 15 wherein the conductors of the turns are in the form of flat solid profiles and comprise circular tangential conductors, wherein the circular tangential conductors of the conductors of the turns have cooling channels which 20 extend in the longitudinal direction of the conductor, wherein open channels are formed on the flat face of these solid profiles, and with the interposition of a flat insulator, the conductors bear one against the other by way of their flat faces and, in the process, 25 define the cooling channels there between.

According to a second aspect of the present invention there is provided a method for producing a conductor for the rotor of an electric generator for producing 30 electricity in power plants of the previous aspect, wherein the method begins with a solid conductor profile which has the same cross-sectional profile over the entire length, and the solid conductor profile is machined by material removal in regions in order to 35 create the prespecified cross-sectional profile, wherein this machining is carried out after or before the conductor is bent into the desired shape. - 8 - 2013337129 31 Μ 2017

According to a third aspect of the present invention there is provided a method for improving the conductors for the rotor of an electric generator for producing 5 electricity in power plants, wherein the existing conductors are replaced by conductors of the first aspect.

It is an object of the present invention to overcome or 10 ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 15 "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". 20 An exemplary embodiment of an electric generator for producing electricity in power plants will be described in the text which follows with reference to the drawings, in which: 25 figure 1 figure 2 30 shows a perspective view of the electric generator (but without the caps at the ends); shows a portion of a detail from the end region of the generator in figure 1, but with only a single turn; figure 3a shows a side view of a half-conductor of the half-turn; 35 9 2013337129 31Jul2017 figure 3b shows a plan view of the half-conductor of the half-turn in figure 3a; figure 4a shows a perspective illustration of the turn which consists of two half-turns before said half-turns are soldered together; figure 4b shows the situation in figure 4a after 10 the two half-turns are soldered together; and figure 5 shows a schematic sectional illustration through the turn. 15

The electric generator for producing electricity in power plants, as illustrated in figure 1, has a shaft 1 with a rotor 2 located on it. This rotor 2 is formed by a field winding 3 which is defined by the two poles. The field winding 3 consists of a plurality of turns 4, wherein these turns 4 each consist of a plurality of electrical conductors 5.

The conductors 5 of the turns 4 are in the form of C-25 shaped half-conductors 5' (figures 3a and 3b) . These two half-conductors 5' are joined to form the overall conductor 5 and, in the process, are connected to one another at the ends by means of a solder point 6. The interface between the two half-conductors 5' of the 30 conductor 5 lies on the longitudinal center plane of the shaft 1 in this case. However, the interface can also be situated elsewhere. The half-conductors 5' form, in their entirety, the half-turns 4' which are then connected to form the solid turn 4. 35

The special feature is the design of the conductors 5 or half-conductors 5' for the turns 4: 10 2013337129 31 Μ 2017 production of the conductors 5 or half-conductors 5' proceeds from a solid profile which is composed of copper and has, in particular, a flat, rectangular 5 cross section. This solid profile is bent to form a C-shape by appropriate mechanical measures, as is illustrated in figures 3a and 3b.

The half-conductors 5' have cooling channels 7 in the 10 axial region which runs in a straight line. Said cooling channels are made in the material by slot-like bores . A second type of cooling channels 8 is provided in the 15 tangential region of the half-conductors 5' which is in the form of an arc of a circle. The basic principle here is that channels, for example in a U-shape, are milled into the top flat face of the half-conductor 5'. One or more of these channels can be provided in this 20 case. These milled channels define the cooling channels 8. Specifically, these cooling channels 8 are realized in such a way that the flat faces of the conductors 5 are placed one on the other with the interposition of a flat insulator 9. However, this means that the milled 25 channels are closed at the top by the insulator 9 located between them, and therefore cooling gas flows longitudinally through the conductor 5 in the form of a cooling channel 8. 30 As stated, production of the conductor 5 or half conductor 5' proceeds from a solid profile which, in the initial state, has the same cross section over the entire length. In the regions in which this cross section is too large, material is correspondingly 35 removed, so that the desired cross section or the desired profile is produced. 11 2013337129 31 Μ 2017

List of reference symbols 1 Shaft 2 Rotor 3 Field turn 4 Turn 4' Half-turn 5 Conductor 5' Half-conductor 6 Solder point 7 Cooling channel 8 Cooling channel 9 Insulator

Claims

Claims

1. An electric generator for producing electricity in power plants, comprising a rotor which has a shaft, and also comprising a field winding which is arranged on the shaft, wherein the field winding consists of a plurality of turns, and the turns each consist of a plurality of conductors, wherein the turns each consist of two halfturns which are electrically and mechanically connected to one another at their two corresponding free ends; wherein the conductors of the turns are in the form of flat solid profiles and comprise circular tangential conductors, wherein the circular tangential conductors of the conductors of the turns have cooling channels which extend in the longitudinal direction of the conductor, wherein open channels are formed on the flat face of these solid profiles, and with the interposition of a flat insulator, the conductors bear one against the other by way of their flat faces and, in the process, define the cooling channels there between.
2. The electric generator as claimed in the preceding claim, wherein the ends of the two half-turns are soldered to one another.
3. The electric generator as claimed in either of the preceding claims, wherein the two half-turns are of C-shaped form.
4. The electric generator as claimed in any one of the preceding claims, wherein the axial conductor sections of the conductors of the turns have cooling channels, which run in the transverse direction, in the form of bores.
5. A method for producing a conductor for the rotor of an electric generator for producing electricity in power plants as claimed in any one of the preceding claims 1 to 4, wherein the method begins with a solid conductor profile which has the same cross-sectional profile over the entire length, and the solid conductor profile is machined by material removal in regions in order to create the prespecified cross-sectional profile, wherein this machining is carried out after or before the conductor is bent into the desired shape.
6. A method for improving the conductors for the rotor of an electric generator for producing electricity in power plants, wherein the existing conductors are replaced by conductors as claimed in any one of the preceding claims 1 to 5.