The present invention relates to a continuous-flow power installation for conversion of mechanical energy to a different energy form, preferably electrical energy. The invention will be described with reference to a wind energy installation, which converts the energy from an air flow to electrical energy. However, it should be noted that the invention can also be used for other types of energy convertors or power installations, for example wave, tide or hydroelectric power installations.
Wind energy installations are known in which a nacelle is mounted on a tower such that it can rotate. A robust support plate or a support frame accommodates the individual components of the drive train—for example rotor bearing, rotor shaft, transmission, generator—and transmits their static and dynamic loads to the tower. The support plate at the same time forms the lower part of the nacelle, which surrounds the drive train in the form of a protective housing. As stated, the support plate is designed to be very robust since, in the case of installation power levels in the Megawatt range, for example, it must support a rotor torque of the order of magnitude of 100 000 Nm or more. This configuration using a support plate is described, for example, in DE 1184567 A2. L-shaped support frames are described, for example, in DE 29609794 U1.
The heavy weight of the support plate and the large amount of space required in the nacelle, which results with the described split configuration of the drive train, are disadvantageous.
Approaches exist for integration of a transmission and generator in a common housing, as is described in DE 10 2004 046 563 B4 or DE 10 242 707 B3. In addition, in some cases, a transmission and the rotor bearing are combined to form a physical unit, for example in EP 11 84 567A2 or WO 1996/011338 A1.
However, concepts such as these have the disadvantage of the increased maintenance effort which results, for example, when an integrated component element is replaced.
The object of the present invention is to specify a continuous-flow power installation whose material consumption and maintenance-friendliness, inter alia, are improved.
This object is achieved by a continuous-flow power installation according to the features of patent claim 1.
The continuous-flow power installation according to the invention for production of electrical power from a fluid flow, that is to say a gas flow or a liquid flow, has a nacelle which is mounted such that it can rotate on a base, in particular a tower, and has a drive train which converts the energy introduced at the rotor from the fluid flow to electrical energy by means of a rotor which is driven by the fluid flow and by means of functional components which are designed for bearing the rotor and/or for bearing the transmission and/or for energy conversion.
The special feature is that at least one of said functional components represents an operationally fixed link for the transmission of static and dynamic loads from the drive train to the tower.
A structure which is required in any case therefore has a dual function: for example, a functional component such as a transmission—and its housing—is therefore used both as a functional component and as a supporting element for power introduction and power transmission of static and dynamic loads directly to the tower. Any nacelle structure which may be required can be made lighter owing to the use of the housing structure of a functional component and its mass. The weight of the tower head or nacelle is reduced, or a more robust nacelle is provided, with a comparable mass. The conventional support plate or the conventional support frame can be dispensed with, or can be designed to be considerably lighter.
In the case of large wind power installations, the dynamic loads comprising the wind pressure, the rotor torque to be supported, the thrust load, etc., considerably exceed the static, mass-dependent loads. All the supporting elements, support plates etc. when designed in the conventional manner have very major dimensions. The functional components, such as bearings or transmissions, likewise have to withstand loads in the same order of magnitude, however. The use of the structure of functional components for transmitting or coupling dynamic loads to the tower helps to result in a considerably lighter structure, since less material is required in the force path between the functional component and the tower.
Further advantageous embodiments of the present invention are the subject matter of the dependent claims.
According to one development of the invention, the at least one functional component is attached to a supporting ring structure of an azimuth bearing. In particular, the functional components on which the highest, in particular dynamic, loads are to be supported, for example the rotor bearing which predominantly supports the thrust load of the rotor, and the transmission on which the main part of the rotor torque is supported, can be attached to the supporting ring structure of the azimuth bearing. The supporting ring structure can be considered to be part of the azimuth bearing, and its radial circumference does not extend significantly beyond the bearing. It also does not have the extent, in particular horizontally longitudinally stretched, extending over the entire nacelle, which a conventional support plate for accommodation of all the functional components of the drive train has.
The housings of the functional components are preferably used to support the loads on the tower. Further material and weight savings can be achieved if a further functional component is fitted to the housing of a functional component such as this, such that its load is likewise supported via the said housing on the tower.
Furthermore, a comparatively lightweight supporting frame for accommodation of additional components, for example a frequency converter, a transformer, a fire protection installation, control electronics, an emergency power source, a cooling system or an air conditioning system, can be fitted to a housing which is supported on the tower.
If the functional components are designed to be weather-resistant, there is no need for a specific protective housing for the nacelle.
A ring generator can be arranged in a front bearing, on the one hand supports its torque itself or via the front bearing on the tower, and on the other hand absorbs and/or damps a portion of the load and/or power peaks on the input side of the drive train itself. Functional components of the drive train which are arranged downstream, such as a transmission or generator, are thus relieved of load and, if required, may be designed for a reduced overload. This subject matter is considered to be an autonomous invention, in conjunction with a wind energy installation, even without the restriction of use of a functional component as a load link to the tower.
The combination of a transmission with a high transmission step-up ratio, for example 1:60 to 1:140 with an asynchronous generator, appears to be advantageous. According to the invention, the generator could be attached to the transmission housing, for example without using a support plate. The torque which acts on the generator, is supported on the transmission housing in this case, and is quite low in comparison to the transmission, does not require any significant increase in the weight of the generator housing. In this case, it is also possible to use a synchronous generator instead of an asynchronous generator.
Further advantageous combinations of functional components are a transmission with low to medium step-up ratios and synchronous generators. In the case of transmissions which are in fact physically small, a dimension increase, for example because of a connection of the generator, is actually more important. However, the absence of an additional support plate results in a weight reduction in any case.
The present invention and its advantages will be explained in more detail in the following text with reference to the exemplary embodiments which are illustrated in the figures, in which:
a shows a schematic side view of a tower head section of a wind energy installation, in which an accommodation shell for functional components of the drive train is provided, and
b corresponds to a rear view of the tower head section illustrated in
In the exemplary embodiments described in the following text, the forces and torques which occur as a result of the wind and of the reaction of the electrical grid system are introduced directly into the tower via the rotor bearing and the azimuth bearing, or via the transmission and the azimuth bearing. One advantage in this case, inter alia, is that, for example, the bearing holder or the bearing shell of the rotor bearing is a part of the nacelle, and the nacelle structure can therefore be simplified, and/or an additional nacelle structure—for example a heavy baseplate—can be dispensed with partially or completely. If the bearing holder is part of the housing structure, then this bearing holder or the bearing itself can expediently be designed such that it is sufficiently stiff with as little use of material as possible. This could be achieved by a cylinder structure or the like for the bearing shell or the bearing, thus providing the latter with a very high area moment of inertia.
One possible embodiment of the bearing for the main shaft is a 2-point bearing, in order to reduce bending torques and axis offset in the transmission to a minimum. Torque bearings or else other forms can be used as a further embodiment of the bearing.
The transmission can be coupled directly to the bearing structure of the main shaft bearing. This should avoid any axis offset. The following embodiments are feasible, inter alia, for the transmission:
1. Machine elements for conversion of torques and rotation speeds in the wider sense in the form of a transmission with a constant or variable step-up ratio of all physical principles of action, for example
2. single-step or multiple-step spur gear transmission
3. single-step or multiple-step epicyclic transmission
4. combinations of 2 and 3
5. differential drive and its derivatives
6. combinations of 2, 3, 5
7. bevel-gear transmission and its derivatives
8. combinations of 2, 3, 5 and 7
9. belt-pulley transmissions
10. combinations of 2, 3, 5, 7 and 9
11. hydrostatic and hydrodynamic transmissions
12. combinations of 2, 3, 5, 9, 11
13. coupling mechanisms
14. combinations of 2, 3, 5, 11, 13
15. epicyclic transmissions
16. combinations of 2, 3, 5, 7, 9, 11, 13, 15
17. electrical transmission as a motor-generator
18. combinations of 2, 3, 5, 7, 9, 11, 13, 15, 17
The generator coupling can vary depending on the transmission and generator variant. If the transmission has only a small number of steps or is physically short, with or without an axis offset, the generator can be in the form of a synchronous generator, an asynchronous generator, or a switch-reluctance generator. In this case, the following types of generator are feasible:
a) for synchronous generator
b) for asynchronous generator
c) further generator types
The output-drive train, which is surrounded by the nacelle 7, comprises as functional components a rotor 9 with rotor blades whose pitch may be variable, a rotor shaft 11 which is mounted such that it can rotate in a rotor bearing 13, a step-up transmission 15, a generator 17 which is connected downstream from the step-up transmission 15, and further auxiliary components such as a frequency converter 19 for controlling the generator 17 and the feed, braking appliances, a hydraulic system, and superordinate control electronics 21, which control the wind energy installation 1.
The rotor bearing 13 is attached to a supporting ring 25 for the azimuth bearing 5. In particular, this transmits thrust and torsion loads as well as static weight forces to the supporting ring 25, and therefore to the tower. The transmission 15 is flange-connected to the rotor bearing 13 or to its housing. Furthermore, the transmission 15 is supported on the supporting ring 25, by which means the high torques which act on the transmission 15 are introduced into the tower. The generator 17 is flange-connected to the transmission housing. In general, this withstands the low torque level which occurs at the generator, without any additional increase in dimensions. A frame-like support structure 23 can be fitted to the housing of the rotor bearing 13, to the transmission housing or to the supporting ring 25, and provides a lightweight mounting platform for the auxiliary components 19 and 21.
The rotor shaft 11 is borne on two points in the rotor bearing 13. The two-point bearing allows at least the static loads from the rotor 9 and rotor shaft 11 to be supported in the rotor bearing 13, thus allowing other components, such as the transmission, to be replaced easily.
The bearings are integrated in or on a structure—see also “housing of the rotor bearing 13”—with as high an area moment of inertia as possible, in order to achieve an adequate stiffness, with little use of material. The bearings which are used may be in the form of ball, cylinder or conical roller bearings, as well as journal bearings. This type of bearing means that the majority of the bending loads from the rotor shaft, which are caused by the wind forces, is not passed into the transmission, resulting in considerable design advantages.
The transmission housing can be connected to the structure of the bearing of the rotor shaft 11 via screws, bolts or other elements which are able to transmit the corresponding forces and torques. The connection of the rotor shaft to the transmission input shaft can be made with the aid of various couplings (rigid or elastic, for example by curved-teeth couplings). The generator shaft can be fitted to the output shaft either directly or via a rigid or elastic coupling, possibly a coupling which damps rotational oscillations. In addition, the housing of the generator can in this case be connected directly to the transmission housing. The purpose of these connections is to cope with the forces and torques which occur between the transmission and the generator. The generator shaft can be designed such that the operating brake and/or holding brake 18, or the braking system, is fitted to it. In order to support the weight force, it is feasible for the transmission and/or the generator also to be supported on a supporting structure which has to be additionally fitted. The operationally fixed connection of the bearing housing, of the transmission and of the generator as well as their linking can be implemented by the described axial connections.
As stated, the support structure 23 can also be fitted for the additional components which are required in a wind energy installation, at the side of and/or behind the drive train, consisting of bearing, transmission, generator and braking system 18. This support structure 23 is thus supported on one or more components of the drive train.
One possible modification of the illustrated embodiment is for the operating and/or holding brake or braking system to be fitted between the transmission and the generator.
Instead of a rotor bearing 13 with two axially separated bearing points, a torque bearing 13′ is provided, in which the rotor shaft 11 is supported in one bearing point. The torque bearing 13′ also supports tilting moments of the rotor shaft 11. The torque bearing 13′ is attached to the supporting ring 25. The transmission 15′ is likewise attached to the supporting ring 25. It is preferably decoupled from the tilting movements of the rotor shaft 11, for example by means of a universally-jointed connection between the rotor shaft 11 and the input shaft of the transmission 15′. Furthermore, the torque bearing 13′ and the transmission 15′ are attached to one another.
The generator 17 is once again flange-connected to the transmission housing. The attachment of further components corresponds to that shown in the first exemplary embodiment.
The change to the bearing for the rotor shaft 11 shortens the physical length of the drive train, in comparison to the first exemplary embodiment. This results in a more compact and lighter nacelle overall.
The rotor shaft 11 is supported at two axially separated bearing points in the bearing 13. The bearing 13 is attached to the supporting ring 25. A transmission 15″ is connected to the bearing 13 and has the supporting ring 25 connected to it on the one hand, and a housing structure of the bearing 13 on the other hand, in a comparable manner to the first exemplary embodiment. The generator 17″ is fitted to the transmission 15″ or to its housing, with the stator of the generator 17″ being mechanically connected to the transmission housing. The generator 17″ is in the form of a ring generator. The free internal area of the generator 17″ accommodates a section of the transmission 17″. This makes it possible to shorten the physical length of the output-drive train and of the nacelle 7″. In order to avoid a complex contact with the rotor of the generator 17″, this generator 17″ could be designed to use permanent-magnet excitation. However, generator types with hybrid excitation or external excitation in the ring structure are also possible.
The purpose of
In order to improve efficiency, it may be worthwhile decoupling the transmission 15″ from the generator 27 in the partial load range, in order to avoid losses in the transmission 15″ at low power levels, and to increase the life of the transmission 15″. A further advantage of this arrangement is the capability to damp drive-train oscillations directly on the rotor shaft 11, by means of the upstream generator 27, by means of a suitable closed-loop control system. In addition, the generator 27 and the generator 17″ result in two independent energy conversion systems, which has the advantage that the installation can still be operated, at a reduced power level, if one system fails.
The first and the second exemplary embodiments can, of course, also be modified in the sense of the fourth exemplary embodiment, that is to say a generator which is driven directly by the rotor shaft 11 can also be integrated with the bearing 13 or 13′ in the nacelles 7 and 7′.
The purpose of
Furthermore, it is feasible in all the embodiments for the supporting ring 25 to be provided with a form of accommodation shell which can support at least the static weight of the individual functional components. This development of the embodiments described above is illustrated in
The above description and the figures serve only to improve understanding of the present invention, and they do not restrict the invention, for example, to the exemplary embodiments or to the described variants. In some cases, the figures have been kept highly schematic, in order to illustrate the methods of operation, the principles of operation, technical refinements and features. In principle, any method of operation, any principle, any technical refinement and any feature which is or are illustrated or described in the figures or in the text can be combined freely and as required with all the claims, any feature in the text and in the other figures, other methods of operation, principles, technical refinements and features which are contained in this disclosure or result from it, as a result of which all feasible combinations of the scope of the disclosure of the invention can be added thereto. In this case, combinations between all the individual embodiments in the text, that is to say in every section of the description text, in the claims as well as combinations between different exemplary embodiments in the text, in the claims and in the figures, are also covered.
In addition, the claims do not restrict or limit the disclosure, and therefore the possibilities to combine all the indicated features with one another. All the indicated features are also explicitly covered individually and in combination with all the other features of the invention, by this disclosure.
1 Wind energy installation
3 Tower head section
5 Azimuth bearing
7 Nacelle
7′ Nacelle
9 Rotor
11 Rotor shaft
13 Rotor bearing
13′ Torque bearing
15 Step-up transmission
15′ Step-up transmission
15″ Step-up transmission
15″′ Step-up transmission
17 Generator
17″ Ring generator
17″′ Generator
18 Braking system
19 Frequency converter
21 Control electronics
23 Support structure
25 Supporting ring
27 Directly driven generator
31 Stationary shaft
33 Casing
35 Rotor of the generator
37 Stator
40 Accommodation shell
42 Attachment means
43 Attachment means
Number | Date | Country | Kind |
---|---|---|---|
10 2008 063 873.0 | Dec 2008 | DE | national |
10 2009 008 340.5 | Jan 2009 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP09/08414 | 11/26/2009 | WO | 00 | 10/24/2011 |