AU2013337129A1

AU2013337129A1 - Electric generator for producing electricity in power plants

Info

Publication number: AU2013337129A1
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: 2015-05-07
Anticipated expiration: 2033-10-15
Also published as: ZA201503634B; WO2014063673A3; AU2013337129B2; DE102012021114B4; DE102012021114A1; WO2014063673A2; EP2912756A2

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

WO 2014/063673 - 1 - PCT/DE2013/000599 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; the invention further relates to a method for producing a conductor for the rotor of an electric generator; the invention finally relates to a method for improving the conductors for the rotor of an 10 electric generator. Electric generators for producing electricity in power plants have a rotor. This rotor initially has a shaft. The two poles of the rotor are arranged on this shaft. 15 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 are embedded in slots. In this case, the conductors 20 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 center point of a circle, are also provided at the 25 ends. During operation of the generator, an electric current flows through the conductors. These electric currents are comparatively high and cause a correspondingly high 30 level of heating. This reduces the service life and also the operational performance. The conductors in the rotor are cooled for this reason. Specifically, the field winding of generator rotors is 35 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 WO 2014/063673 - 2 - PCT/DE2013/000599 variants are in order of increasing effectiveness of the cooling and therefore the output densities of the generator which can be achieved): 5 Variant 1 is indirect cooling due to the cooling gas flowing past the narrow sides of the conductors of the winding. Variant 2 is direct cooling with the cooling gas 10 flowing transversely through the conductor through corresponding radial bores. Variant 3 is likewise direct cooling with the cooling gas flowing longitudinally through the conductor. 15 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. 20 Single or double hollow profiles are usually used for variant 3. Rotor windings are preferably cooled either in accordance with variant 1 or in accordance with variant 25 2 or in accordance with a combination of variants 1 and 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 therefore a minimum number of solder points in the 30 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 mechanical weak point. 35 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 variant 1 or in accordance with variant 2 or in WO 2014/063673 - 3 - PCT/DE2013/000599 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 5 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 10 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 15 point. Taking this as a basis, the invention is based on the object of providing an electric generator for producing electricity in power plants, in which electric 20 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 25 of claim 1. As a result, an electric generator for producing electricity in power plants is provided, in which electric generator the conductors of the turns have 30 only 2 solder points. The cooling capacity of the 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 35 another at their ends. The generator according to the 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 WO 2014/063673 - 4 - PCT/DE2013/000599 this case, 2 different conductor profiles are used per turn, but it is possible for said conductor profiles to be produced from only one type of conductor profile. Since the turns are designed as half-turns, the number 5 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 level of loading. 10 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 mechanical and electrical connection has proven to be effective. 15 According to the development in claim 3, it is proposed that the two half-turns are of C-shaped form. In this case, the interface with the solder points of said half-turns is situated between the two C-shaped half 20 turns 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. 25 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 radial direction in relation to the shaft as bores. 30 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 the conductors. 35 The development as claimed in claim 5 proposes one option for direct cooling with the cooling gas flowing longitudinally through the conductor. These cooling WO 2014/063673 - 5 - PCT/DE2013/000599 channels are intended for the circular tangential conductor. A preferred structural solution for this is proposed by 5 the development as claimed in claim 6. In this case, 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 10 provided in this case. These channels are closed at the 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 15 conductor. As a result, a cooling channel which runs in 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 20 material out of the flat top face of the conductor. As a further technical solution, claim 7 proposes a method for producing a conductor for the rotor of an electric generator for producing electricity in power 25 plants. The core idea is that the conductor starts with a solid profile which, in the initial state, has the same cross-sectional profile over the entire length. 30 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 section required. This is the relatively wide profile of the profile usually used previously (usually the 35 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 (the previous relatively narrow profile) by machining.

WO 2014/063673 - 6 - PCT/DE2013/000599 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 900 arc at 5 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, 10 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. 15 As a further technical solution, claim 8 proposes a 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 20 plants, specifically to improve the conductors of said electric generators, by the old, above-described conductors being replaced by conductors or turns according to the invention. 25 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: 30 figure 1 shows a perspective view of the electric generator (but without the caps at the ends) ; figure 2 shows a portion of a detail from the end 35 region of the generator in figure 1, but with only a single turn; WO 2014/063673 - 7 - PCT/DE2013/000599 figure 3a shows a side view of a half-conductor of the half-turn; figure 3b shows a plan view of the half-conductor 5 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 10 together; figure 4b shows the situation in figure 4a after the two half-turns are soldered together; and 15 figure 5 shows a schematic sectional illustration through the turn. The electric generator for producing electricity in 20 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 25 electrical conductors 5. The conductors 5 of the turns 4 are in the form of C shaped half-conductors 5' (figures 3a and 3b) . These two half-conductors 5' are joined to form the overall 30 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 conductor 5 lies on the longitudinal center plane of the shaft 1 in this case. However, the interface can 35 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.

WO 2014/063673 - 8 - PCT/DE2013/000599 The special feature is the design of the conductors 5 or half-conductors 5' for the turns 4: production of the conductors 5 or half-conductors 5' 5 proceeds from a solid profile which is composed of copper and has, in particular, a flat, rectangular cross section. This solid profile is bent to form a C shape by appropriate mechanical measures, as is illustrated in figures 3a and 3b. 10 The half-conductors 5' have cooling channels 7 in the axial region which runs in a straight line. Said cooling channels are made in the material by slot-like bores. 15 A second type of cooling channels 8 is provided in the 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 20 milled into the top flat face of the half-conductor 5'. One or more of these channels can be provided in this 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 25 are placed one on the other with the interposition of a flat insulator 9. However, this means that the milled 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 30 cooling channel 8. 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 35 entire length. In the regions in which this cross section is too large, material is correspondingly removed, so that the desired cross section or the desired profile is produced.

WO 2014/063673 - 9 - PCT/DE2013/000599 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

1. An electric generator for producing electricity in power plants, 5 comprising a rotor (2) which has a shaft (1), and also comprising a field winding (3) which is arranged on the shaft (1), wherein the field winding (3) consists of a plurality of turns (4), and the turns (4) each consist of a 10 plurality of conductors (5), characterized in that the turns (4) each consist of two half-turns (4') which are electrically and mechanically connected to one another at their two corresponding free ends. 15

2. The electric generator as claimed in the preceding claim, characterized in that the ends of the two half-turns (4') are 20 soldered to one another.

3. The electric generator as claimed in either of the preceding claims, characterized 25 in that the two half-turns (4') are of C-shaped form.

4. The electric generator as claimed in one of the preceding claims, characterized 30 in that the axial conductor sections of the conductors (5) of the turns (4) have cooling channels (7), which run in the transverse direction, in the form of bores.

5. The electric generator as claimed in one of the 35 preceding claims, characterized in that the circular tangential conductors of the conductors (5) of the turns (4) have cooling channels WO 2014/063673 - 11 - PCT/DE2013/000599 (8) which extend in the longitudinal direction of the conductor (5).

6. The electric generator as claimed in claim 5, 5 characterized in that the conductors (5) of the turns (4) are in the form of flat solid profiles, in that open channels are formed on the flat face of these solid profiles, and 10 in that, with the interposition of a flat insulator (9), the conductors (5) bear one against the other by way of their flat faces and, in the process, define the cooling channels (8) therebetween. 15

7. A method for producing a conductor (5) for the rotor (2) of an electric generator for producing electricity in power plants as claimed in one of claims 1 to 6, characterized 20 in that the method begins with a solid conductor profile which has the same cross-sectional profile over the entire length, and in that the solid conductor profile is machined by material removal in regions in order to create the 25 prespecified cross-sectional profile, wherein this machining is carried out after or before the conductor (5) is bent into the desired shape.

8. A method for improving the conductors (5) for the 30 rotor (2) of an electric generator for producing electricity in power plants, characterized in that the existing conductors or turns are replaced by conductors (5) or turns (4) as claimed 35 in one of claims 1 to 6, or are replaced by conductors (5) or turns (4) which are produced as claimed in claim 7.