EP2852758A1

EP2852758A1 - Generator of a gearless wind power plant

Info

Publication number: EP2852758A1
Application number: EP13724560.1A
Authority: EP
Inventors: Wojciech GIENGIEL
Original assignee: Wobben Properties GmbH
Current assignee: Wobben Properties GmbH
Priority date: 2012-05-22
Filing date: 2013-05-15
Publication date: 2015-04-01
Also published as: CN104334873A; CN104334873B; CL2014003147A1; MX2014013458A; RU2014151732A; US20150102605A1; CA2870404A1; TWI545253B; JP6181161B2; ZA201407087B; WO2013174700A1; BR112014027340A2; AU2013265478B2; RU2599411C2; DE102012208550A1; NZ700703A; CA2870404C; AU2013265478A1; TW201408874A; KR20140143443A

Abstract

The invention relates to a generator (1) of a gearless wind power plant (100), having a stator (2) and a rotor (4), wherein the stator (2) and/or the rotor (4) have/has windings (14, 30) made of aluminium.

Description

Generator of a gearless wind turbine

The present invention relates to a generator of a gearless wind turbine and a wind turbine with such a generator and a method for building a wind turbine.

Gearless wind turbines are well known. They have an aerodynamic rotor which, driven by the wind, directly rotates an electrodynamic rotor, which is also called a rotor to avoid confusion. The aerodynamic rotor and the rotor are rigidly coupled and have the same speed. Since the aerodynamic rotor rotates relatively slowly in modern wind turbines, for example in the range between 5 and 25 revolutions per minute, the rotor also turns correspondingly slowly. For this reason, a generator of a modern gearless wind turbine is a Vielpolgenerator large diameter.

Thus, such large generators have the disadvantage that they are difficult to handle due to their size, in particular are difficult to assemble and can cause problems during transport due to their size. They have copper windings on a large scale and are therefore very difficult. Accordingly complex support structures must be formed.

However, copper is unrivaled as a material for electrical wiring in a generator due to its good electrical properties. In particular, there is so far no other, in sufficient amount existing material that has as high a conductivity as copper and at the same time relatively unproblematic processable and thereby has its properties basically over the entire temperature range, which naturally occurs on Earth, where wind turbines can be set up. Due to the high conductivity, it is thus possible to build generators at the appropriate place correspondingly small.

The size of generators is limited today especially by the transport. For example, a generator diameter, ie an external diameter of the generator, of 5 m is a critical quantity for the transport of generators. correspond Accordingly, the air gap diameter, ie the diameter of the generator in the region of the air gap, is correspondingly small. The air gap is between the stator and rotor and its diameter is twice the thickness of the stator - in the case of an internal rotor - or twice the thickness of the rotor - in the case of an external rotor - smaller than the total diameter of the generator. The air gap diameter decisively determines the efficiency and electrical performance of the generator. In other words, the largest possible air gap diameter should be sought. Accordingly, an external stator or an external rotor is to be made as slim as possible, so that the air gap diameter can be made as large as possible for a given outside diameter of about 5 m.

One possibility is to expand the generator in the axial direction, ie to make it longer. As a result, the generator can be increased in its nominal power basically at the same air gap diameter. However, such extensions have stability problems in the axial direction. In particular, if the lying outside of the air gap part of the generator is to be formed as slim as possible, such a generator longer ausgestalteter quickly come to its stability limits. It adds that the windings have a large weight, but basically can not contribute to the mechanical stability.

The present invention is therefore based on the object to address at least one of the above problems. In particular, a generator of a gearless wind turbine is to be improved in terms of performance, stability and / or weight. At least an alternative embodiment to previous solutions to be proposed.

According to the invention, a generator according to claim 1 is proposed. Such a generator of a gearless wind turbine has a stator and a rotor. The stator and / or the rotor has windings made of aluminum.

It was inventively namely recognized that although aluminum has a lower conductivity than copper, but due to its relatively low weight in the overall concept for the generator can still be beneficial. The poorer conductivity of the aluminum compared to copper must first be met with a larger cross section of the respective windings, which initially leads to a higher volume requirement. In contrast to this, however, aluminum is Lighter than copper, so that the generator in its entirety is still lighter. As a result of the lower weight, the requirements for the supporting structures, that is to say the mechanical construction of the wind energy plant as a whole and also for the mechanical structure of the generator, may possibly be lower. As a result, weight can again be saved and, if necessary, volume recovered.

The use of aluminum windings means, in particular, that the windings are made of aluminum and, of course, have insulation, in particular insulating varnish or the like. In principle, however, alloys are also suitable for the aluminum, which can influence, for example, some properties of aluminum, such as its processability, in particular flexibility. It is crucial that aluminum is available as a lightweight electrical conductor and forms a majority of the respective winding. It does not matter for some admixtures, which hardly change anything at the basic conductivity and at the basic specific weight of the aluminum. The aluminum should be decisive for the weight and conductivity of the windings.

It is preferably proposed that the generator is an external rotor. Thus, the stator, namely the standing part, is inside and around this the runner rotates. This initially has the advantage that the air gap diameter can be increased in principle, because the rotor basically requires a smaller thickness than the stator. Correspondingly, the rotor requires less space between the air gap and a maximum outer diameter, so that the air gap diameter can be increased for a given outer diameter.

Furthermore, it should be noted that in a stator often laminated cores are provided, which are provided on the air gap side with windings. In the case of an external rotor, such a laminated stator core can be reinforced inwardly, ie, in any way, to the central axis of the generator and can be reinforced with cooling channels and the like. be provided. Here is in the case of an external rotor plenty of space for the stator, so that the provision of a generator of the outer rotor type de facto much space for the stator is created.

The rotor, at least if this is foreign-excited, is constructed entirely differently, namely regularly composed of rotor poles equipped with windings, which are connected at their side facing away from the air gap on a supporting structure, namely a cylinder jacket. In the case of a generator of the external rotor type, the pole shoe bodies therefore basically extend slightly from the air gap in a star shape Outside. In other words, the available space increases from the air gap to the supporting structure. The accommodation of windings for the external excitation is thus facilitated because in the case of an external rotor here more space is available.

Thus, the use of aluminum in any case positively affects the exciter windings of the rotor with the additional volume of space that results for the external rotor type.

The aluminum windings can thus be provided in an advantageous manner for the runner. The described additional space for supporting the stator can also be used to provide aluminum windings in the stator. For this purpose, the stator can provide, for example, additional winding space through an enlargement in the radial direction. The air gap diameter is unaffected. Also, any increase in the magnetic resistance in the stator is likely to be negligible compared to the magnetic resistance of the air gap. Optionally, with a lighter rotor that has become lighter due to the use of light aluminum over a copper rotor, a more rigid structure for the rotor can be achieved, which could allow a reduction in the air gap thickness, which could reduce the magnetic resistance.

Preferably, a generator is proposed with an air gap diameter of over 4.3 m. This manifests that the present invention relates to generators of large gearless wind turbines. The present invention does not claim to be the invention of a generator with aluminum windings. The use of aluminum windings for a large generator of a modern gearless wind turbine has so far been out of the art, however, because it was trying instead to optimize generators elsewhere. This involves creating the lowest possible volume, which has hitherto excluded the use of aluminum as the winding material for the skilled person.

According to a further embodiment, it is proposed that an external rotor is used as a generator type, wherein the rotor is composed in the circumferential direction of a plurality of rotor segments, in particular of two, three or four rotor segments. In particular, the rotor segments are prepared to be assembled on site when setting up the wind turbine. Preferably, however, the stator is formed in one piece, in particular it has a continuous winding for each phase. By using aluminum as a winding material runners, at least those of a separately excited synchronous generator, have less weight and thus favor a construction in which the rotor is assembled. Already with the use of two in the reason each semi-circular rotor segments, a generator can be created with a diameter of more than 5 m, without the critical transport size of 5 m is exceeded. When using a one-piece stator of such an external rotor, the outer diameter of the stator, which corresponds approximately to the air gap diameter, about the critical transport size, in particular 5 m. The runner is then assembled on the spot when road transport is no longer required. In this case, the exact size of the generator, namely the rotor segment is only a minor problem. Now much more decisive is the weight of the elements. However, the weight can be reduced by the use of aluminum. To achieve the same absolute conductivity instead of copper with aluminum, you need about 50% more winding volume, but still weighs only half of the corresponding copper winding. Despite an increase in volume, therefore, the weight can be drastically reduced when aluminum is used. By using a split runner, however, the upper limit for the volume is no longer, the runner can be made slightly larger and this leads - paradoxically - to a lighter runner, because now aluminum can be used.

Accordingly, it is advantageous that the generator is designed as a third-excited synchronous generator and the rotor comprises excitation windings made of aluminum. This is as described for an external rotor, in particular split external rotor, particularly advantageous, but may also be favorable for an internal rotor. Preferably, the generator has a nominal power of at least 1 MW, in particular at least 2 MW. This embodiment also emphasizes that the invention relates in particular to a generator of a gearless wind turbine of the megawatt class. Such generators are being optimized today, and so far aluminum has not been considered as material for the windings. However, it has been recognized that the use of aluminum can be beneficial and must not be a limitation or degradation to copper. Even if there are already generators with aluminum windings that may have been developed in certain countries due to shortage of raw materials at certain times, there can be no indication or suggestion to equip a generator of a gearless wind turbines of the megawatt class with aluminum windings. Preferably, the generator is designed as a ring generator. A ring generator describes a construction of a generator, in which the magnetically active region is arranged substantially on an annular region concentrically around the axis of rotation of the generator. In particular, the magnetically active region, namely of the rotor and the stator is arranged only in the radially outer quarter of the generator.

A preferred embodiment proposes that the generator is designed as a slow-running generator or as a multi-pole generator with at least 48, at least 72, in particular at least 192 stator poles. Additionally or alternatively, it is advantageous to form the generator as a six-phase generator. Such a generator is to be provided in particular for use in modern wind turbines. Due to its multipolarity, it allows a very slow running operation of the rotor, which adapts due to the gearlessness of a slowly rotating aerodynamic rotor and is particularly good to use with this. It should be noted that at 48, 72, 192 or even more stator poles a correspondingly high winding effort is available. In particular, if such a winding is phased throughout, a conversion to aluminum windings is a huge development step. Already the stator body to be wound, namely the Blechpakte are adapted to the changed space requirements. Also, the handling of the aluminum for such windings is to be re-learned and, if necessary, aluminum alloys should be provided to facilitate such a changed winding. A changed stator is also to be taken into account with regard to its attachment in the wind turbine, in particular on a corresponding stator. This can change connection points, both mechanical and electrical, and it opens the possibility to adapt the entire support structure to the reduced weight. In particular, the use of a wind turbine, in which the generator is thus not on a machine floor or its own foundation, basically leads to a fundamental generator change to the need for a complete overhaul of the nacelle construction of the wind turbine, or has even far-reaching consequences. Also, a wind turbine is proposed, which uses a generator, as has been described at least according to one of the above embodiments.

Also, a method for building such a wind turbine is proposed. Preferably, this includes the mounting of a wind turbine with a generator with divisible external rotor. For this purpose, it is proposed to first mount the stator of the generator on a tower, namely on a nacelle or the first part of the nacelle.

The runner is then assembled on-site or in parallel at the site or in the vicinity thereof, such as in a mini factory. The thus assembled rotor is then mounted on the tower together with the already mounted stator, so that the composite rotor together with the stator essentially forms the generator.

The invention will now be explained in more detail by way of example with reference to exemplary embodiments.

Fig. 1 shows a wind turbine in a perspective view.

Fig. 2 shows a generator of the internal rotor type in a side sectional view.

Fig. 3 shows a generator of the outer rotor type in a side sectional view.

Fig. 4 shows schematically two pole pieces of a rotor of an internal rotor type generator.

Fig. 5 shows schematically two pole pieces of a rotor of a generator of the external rotor type.

FIG. 1 shows a wind energy plant 100 with a tower 102 and a nacelle 104. A rotor 106 with three rotor blades 108 and a spinner 110 is arranged on the nacelle 104. The rotor 106 is set in rotation by the wind in rotation and thereby drives a generator in the nacelle 104 at.

Fig. 2 shows a generator 1 of the internal rotor type and thus an external stator 2 and a rotor lying inside 4 between the stator 2 and the rotor 4 is the air gap 6. The stator 2 is a stator 8 on a stator 10 worn. The stator 2 has laminated cores 12 which receive windings, of which windings 14 are shown. The winding heads 14 basically show the winding wires laid out of a stator slot into the next stator slot. The laminated cores 12 of the stator 2 are attached to a support ring 16, which also can be regarded as part of the stator 2. By means of this support ring 16, the stator 2 is fixed to a stator flange 18 of the stator 8. In addition, the stator bell 8 carries the stator 2. In addition, the stator bell 8 can provide fans for cooling, which are arranged in the stator bell 8. As a result, air for cooling can also be pressed through the air gap 6, thereby cooling in the region of the air gap.

Fig. 2 also shows the outer periphery 20 of the generator 1. Only handling tabs 22 protrude beyond, but this is not a problem, since they are not present over the entire circumference.

At the stator 10 is followed by an only partially shown axle journal 24. On the journal 24 of the rotor 2 is mounted on a rotor bearing 26. For this purpose, the rotor 2 is fixed to a hub portion 28, which is also connected to rotor blades of the aerodynamic rotor, so that the rotor blades moved by the wind can rotate the rotor 4 via this hub portion 28.

The rotor 4 has pole shoe bodies with exciter windings 30. Towards the air gap 6, part of the pole piece 32 can still be seen on the exciter windings 30. To the air gap 6 side facing away, ie inwardly of the pole piece 32 with the excitation winding, which it carries on a run-bearing ring 34 attached, which in turn is secured by a rotor support 36 to the hub portion 28. The rotor support ring 34 is basically a cylinder jacket-shaped, solid, solid section. The rotor carrier 36 has a plurality of struts.

It can be seen in Fig. 2 that the radial extent of the rotor 4, namely from the run-yielding ring 34 to the air gap 6 is significantly less than the radial extent of the stator 2, namely from the air gap 6 to the outer periphery 20th

In addition, a support length 38 is shown, which describes approximately the axial extent of the stator 8 to the end facing away from the stator 2, namely the winding head 14 there. In this construction, this axial length of support is relatively long and it shows how far the stator 2 from the stator bell 8 must be free. Because of the inner rotor 4 namely on the side facing away from the stator 8 no further support or storage facility for the stator 2 is present. The generator 301 of FIG. 3 is of the external rotor type. Accordingly, the stator 302 is inside and the rotor 304 outside. The stator 302 is supported by a central stator support construction 308 carried on the stator support 310. For cooling, a fan 309 is shown in the stator support structure 308. The stator 302 is thus carried centrally, which can greatly increase the stability. Furthermore, it can be cooled from the inside by the blower 309, which is only characteristic of other blowers. The stator 302 is accessible from the inside in this construction.

The rotor 304 has an outer rotor support ring 334 which is fixed to a rotor carrier 336 and is supported by this on the hub portion 328, which in turn is supported via a rotor bearing 326 on a journal 324.

Due to the basically reversed arrangement of stator 302 and rotor 304 results in an air gap 306 having a larger diameter than the air gap 6 of FIG. 2 of the generator 1 of the internal rotor type.

FIG. 3 also shows a favorable arrangement of a brake 340, which can fix the rotor 304 if required via a brake disk 342 connected to the rotor 304. In this case, the tightened brake 340 results in a stable state in which the rotor 304 is held in an axial direction on two sides, namely on one side ultimately via the bearing 326 and on the other side via the tightened brake 340.

In Fig. 3, an axial support length 338 is also shown, which also shows a mean distance of the Statortrag construction 308 to the rotor carrier 336. Here, the distance between the two support structures of the stator 302 and rotor 304 is significantly reduced from the axial support length 38 shown in the internal rotor type generator in FIG. Also, the axial length of support 38 of FIG. 2 indicates an average distance between the two supporting structures for the stator 2 on the one hand and the rotor 4 on the other. The smaller such an axial length of support 38 or 338, the higher the stability that can be achieved, in particular also a tilting stability between stator and rotor.

The outer diameter 344 of the outer periphery 320 is identical in both shown generators of FIGS. 2 and 3. The outer circumference 20 of the generator 1 of FIG. 2 thus also has the outer diameter 344. Despite the same outer diameter 344, it is possible in the construction of FIG. 3, which shows the outer rotor type generator 301, to achieve a larger air gap diameter for the air gap 306 than the air gap 6 of FIG. FIG. 4 shows an external stator 402 and an internal rotor 404. FIG. 4 shows very diagrammatically two pole shoe bodies 432 with a shaft 450 and a pole shoe 452. Between the two pole shoe bodies 432, in particular between the two shafts 450, a winding space 454 is formed. Herein, the lines of excitation windings 430 are to be arranged. Since each pole piece body 432 carries excitation windings 430, the winding space 454 must basically receive electrical leads from two exciter windings 430.

Due to the fact that the pole shoe bodies 432 of FIG. 4 belong to an inner rotor, the shanks 450 converge from the pole shoes 452, as a result of which the winding space 454 narrows. This may cause problems in housing the field windings 430.

In Fig. 5, an inner stator 502 and an outer rotor 504 are shown. Fig. 5 shows a similar schematic representation of two Polschuhkörpern 532 but of an external rotor. Here, it can be seen that the shanks 550 move away from the pole shoes 552, so that a winding space 554 widens and thus creates a lot of space for lines of exciter windings 530.

By means of FIG. 5, in particular in comparison to FIG. 4, it is illustrated that solely by the use of an external rotor a significantly increased winding space 554 can be created, which favors the use of aluminum as material for the windings. In addition, the illustrated increase in the absolute winding space 554 versus the absolute winding space 454 in the external rotor illustrated in FIG. 5 can improve the handling and in particular the assembly.

In addition, according to FIG. 4, the adjoining connection space 456, which adjoins the shanks 450, is narrowed. By way of illustration, the shafts 450 are further drawn by dashed lines. In particular, it is problematic how the pole shoe bodies and thus the poles of the rotor as a whole are basically provided and installed individually. The basically existing space in the connection space 456 can thus be difficult to use.

In contrast, a corresponding terminal space 556 increases according to FIG. 5 due to the arrangement as an external rotor. Thus, a solution is provided which proposes to use aluminum in generators. What initially appears to be an antiquated stopgap solution that a person skilled in the art would have to reject for designing a modern generator of a wind turbine if he has copper available turns out to be an advantageous solution. The use of aluminum in generators may be less advantageous if it is an internal rotor. Internal rotor generators are structurally limited by their design. In external rotor generators, however, the generators are defined differently or constructed fundamentally different, which allows the use of aluminum and even be beneficial. It is also to be mentioned that in the calculation of a rotor this usually has to be based on a predetermined air gap radius r. Starting from this air gap radius, the inner rotor is limited inwards, because the shafts of the poles, the extension of which is illustrated by the auxiliary lines 457 in Fig. 4, would otherwise meet at a point P shown in FIG. As a result, the radial extent of an internal rotor is limited. In the case of an external rotor, this limit does not arise because the shafts diverge outwards, as illustrated by the auxiliary lines 557, therefore do not meet and are therefore not limited in their radial extent. As a result, an external rotor is particularly well suited for use with aluminum windings that require more winding space. It is proposed to use aluminum for the stator or for the rotor or both. When constructing an external rotor, a larger air gap diameter can be achieved, which allows or favors the use of aluminum.

Further advantages are that the costs for aluminum are lower and sometimes also better material accessibility is given, at least in the case of a construction of the external rotor. It is thus avoided copper, at least in the stator or the rotor. Although a higher volume efficiency can be achieved with copper in principle, but this requires a higher price, both in the direct cost of the material copper and possibly in the sense of a cost of construction and the necessary supporting structure for the heavy copper.

Claims

A generator (1) of a gearless wind turbine (100) comprising a stator (2) and a rotor (4), wherein the stator (2) and / or the rotor (4) comprises windings (14, 30) made of aluminum.

2. Generator (1) according to claim 1, characterized in that the generator (1) is an external rotor.

3. Generator (1) according to claim 2, characterized by an air gap diameter (6) of more than 4.3 m.

4. generator (1) according to claim 2 or 3, characterized in that the rotor (4) is composed in the circumferential direction of a plurality of rotor segments, in particular of two or four rotor segments, wherein the rotor segments are in particular prepared for setting up the wind turbine (100 ) to be assembled on site, wherein the stator (2) is preferably formed in one piece, in particular a continuous winding (14).

5. Generator (1) according to any one of the preceding claims, characterized in that the generator (1) is designed as a third-excited synchronous generator (1) and the rotor (4) comprises excitation windings (30) made of aluminum.

6. Generator (1) according to any one of the preceding claims, characterized by a rated power of at least 500 kW, at least one MW, in particular of at least two MW.

7. Generator (1) according to any one of the preceding claims, characterized in that the generator (1) is designed as a low-speed generator (1) and / or multipolar generator (1) with at least 48, at least 72, in particular at least 192 stator poles and / or as a 6-phase generator (1) is formed.

8. Wind energy plant (100) with a generator (1) according to one of the preceding claims.

9. A method of constructing a wind turbine (100) according to claim 8 comprising the steps

Mounting the stator (2) of the generator (1) on a tower (102) of the wind energy plant (100) to be erected,

- Assembling the rotor (4) of the generator (1) on site at or near the site and

- Mounting the thus assembled rotor (4) on the tower (102) to form together with the already mounted stator (2) the generator (1).