DESC:3. PREAMBLE TO THE DESCRIPTION

The following specification describes the invention.

FIELD OF THE INVENTION

The present invention relates to a wind turbine, and more particularly to a damper arrangement for damping vibrations of a wind turbine. Further, the present invention relates to a wind turbine. In addition, the present invention is also directed to a method of damping vibrations of a wind turbine.

The present invention is directed to the technical field of wind turbines, in particular to wind turbines of the horizontal type, that is the wind turbines which comprise a horizontal axis and a rotor being directed against the wind.

Such wind turbines generally comprise a nacelle incorporating a drive train. The nacelle is mounted to a tower. A rotor with one or more rotor blades, particularly with three rotor blades, is connected to the drive train via a hub, to which the rotor blades are mounted. The rotor rotates around its rotational axis. In general, the drive train comprises a gear device and a generator device. Usually, the rotor is coupled to a drive shaft of the gear device, said drive shaft in turn being coupled to an output shaft of the gear device. The gear device is coupled to the generator device which comprises a rotor component and a stator component for generating electric energy. In particular, the output shaft of the gear device is coupled to a generator shaft of the generator device, said generator shaft being coupled to the rotor component of the generator device as well.

BACKGROUND

Wind turbines are becoming taller and taller. Often, modern wind turbines reach an overall height of more than 100 metres. Typically, wind turbines are slender structures. The nacelle including the rotor with its rotor blades is provided at the top of the tower. Therefore, the wind turbine provides a lot of contact surface for the wind. When the wind hits the wind turbine, the wind turbine, especially the tower, the rotor with its rotor blades and the nacelle are exposed to vibrations. Such vibrations can have high amplitudes. However, these vibrations negatively influence the performance of the wind turbine. Additionally, negative vibrations are also generated by forces induced on the nacelle and the tower by the rotating rotor blades.

The existence of such vibrations is a long-known phenomenon. In order to compensate such vibrations different types of solutions using damper arrangements for compensating vibrations have been developed in the prior-art.

WO 2015/062608 A1 for example discloses a solution of damping oscillations in a wind turbine tower, which comprises connecting a bag of material or liquid to a tower component at a first lateral distance away from a tower wall. The bag is also suspended from the tower component by a first vertical distance. The height of the tower component is known such that the first vertical distance corresponds to a particular height within the tower. The first lateral distance, first vertical distance, and mass of the bag are such that the bag is configured to hit said tower wall during oscillations in said wind turbine tower, in order to damp said oscillations in said wind turbine tower.

Other solutions using an oscillating flywheel mass are described in US 2010/0314883 A1, US 2012/0063915 A1, US 2011/0056151 A1 or EP 1 008 747 A2. Other types of damper solutions using passive damper arrangements are disclosed in WO 2014/108277 Al, WO 2015/113932 Al, WO 2016/037958 Al or in US2015/211496 Al.

The aforementioned damper arrangements are typically so called passive damper arrangements. Generally, passive damper arrangements do not import any additional energy into the existing system. They solely serve to isolate and to damp mechanical vibrations that have been transmitted into the existing system. Further, such passive damper arrangements require a lot of installation place. Furthermore, passive damper arrangements are slow.

Instead of passive damper arrangements, it is also known in the prior-art to use active damper arrangements. Using an active damper arrangement, an existing system, a wind turbine for example, is expanded by an additional, individually adapted active system, said system being adapted of independently influencing the vibration behaviour of the existing system.

EP 2 123 906 A1 describes a solution of such an active damper system, wherein a rotor rotational speed of the wind turbine is determined and wherein the rotor rotational speed is controlled such that a critical rotor speed is avoided. However, it is a drawback of this known solution that the performance of the wind turbine is reduced. Furthermore, any vibrations of the tower caused by the wind cannot be compensated.

US 2008/0206051 discloses a different solution using an active damping method, wherein the active damper arrangement calculates a suitable pitch angle of the rotor blades in order to cancel out the vibrations of the nacelle to which the rotor is mounted. A similar solution of this kind is described in US 2013/0195653 A1, said solution comprising, besides the active damper system, a passive damper system as well.

US 2008/0145222 A1 discloses a wind turbine comprising an active damper system for reducing vibrations of the tower of the wind turbine. The damper system includes a mass being movable with respect to the tower and a drive mechanism including a number of two or more actuators for actively controlling the mass movement with respect to the tower of the wind turbine. However, the damper system requires the use of two or more actuators in order to move the mass. The entire damper system is fixedly mounted to the tower. The mass is arranged in the centre of the tower since the mass must be capable of being moved in all of the horizontal directions. Therefore, the damper system and in particular its mass blocks the entire cross- section of the tower. Furthermore, the actuators of the damper system do not contribute to the movable mass.
The damper arrangements as mentioned before using a mass require a lot of installation place, since the mass has to be moved in only one horizontal plane in all different moving directions.

SUMMARY OF THE INVENTION

Starting from the aforementioned state of the art, it is the object of the present invention to provide a damper arrangement for damping vibrations of a wind turbine as well as a wind turbine and a method of damping vibrations of a wind turbine that avoid the aforementioned drawbacks.

According to the invention, the object is solved by the damper arrangement with the features according to independent claim 1, which is the first aspect of the invention, by the wind turbine with the features of independent claim 13, which is the second aspect of the invention, and by the method with the features of independent claim 15, which is the third aspect of the invention. Further features and details of the invention become apparent from the dependent claims, from the description as well as from the drawings. Therein, features and details which are described in connection with one aspect according to the invention apply with respect to their disclosure in their entirety also to the other aspects according to the invention, so that any statements made with respect to one aspect of the invention also apply to their full extent to the other aspects of the invention and vice versa.

The underlying concept of the present invention is that any vibrations of the wind turbine can be compensated by use of a specific damper arrangement, which can be installed inside the wind turbine, preferably inside the tower and/or the nacelle thereof.

The present invention according to its three aspects is directed to the technical field of wind turbines, in particular to the technical field of horizontal wind turbines. Such wind turbines are generally known in the prior-art.

According to a preferred embodiment, the wind turbine comprises a nacelle which incorporates a drive train. The drive train transmits the rotor speed to the generator where it is converted into electric energy. The wind turbine comprises a rotor being connected to said drive train, said rotor preferably comprising a hub and at least one rotor blade, preferably three rotor blades being mounted to said hub. The rotor is pivotally mounted around a rotational axis to the drive train. In order to transform the rotational energy of the rotor into electric energy, the drive train, to which the rotor of the wind turbine is mounted, comprises a number of different components. One of these components is a gear device. At its entrance side, the gear device is connected to the rotor via a drive shaft, a slow running drive shaft for example. The rotor is connected to said drive shaft via its rotor hub. On its exit side, the gear device comprises an output shaft, a fast running output shaft for example. The gear device has the function to transform the low speed or low revolution and the high torque of the drive shaft into a high speed or high revolution and a small torque of the output shaft. The gear device is connected to the generator device. In particular, the output shaft of the gear device is coupled to a generator shaft of the generator. The generator device generates electric energy from the rotational energy which is provided by the gear device. For this purpose, the generator device, preferably, comprises a stator component and a rotor component, said rotor component being coupled to the generator shaft. The nacelle is mounted at the top of a tower of said wind turbine. At its lower base end, the tower is anchored to the ground by means of a foundation.

According to the first aspect of the present invention, a damper arrangement for damping vibrations of a wind turbine is provided, said damper arrangement comprising at least one, preferably two active damper device(s), each damper device comprising a mass and a guiding device, to which the mass is movably connected by means of a drive, said guiding device having an extension direction, said drive being adapted for moving the mass along the guiding device in the extension direction thereof, said drive being a portion of said mass.

In particular, a damper arrangement is a device that compensates or that is capable of compensating any vibrations induced on the wind turbine, on the tower and/or on the nacelle thereof, for example. The damper arrangement is adapted to be mounted to the wind turbine. That means, in its operational state, the damper arrangement is mounted to the wind turbine, particularly inside the wind turbine. According to one preferred embodiment, the damper arrangement is mounted inside the tower of the wind turbine. According to another preferred embodiment, the damper arrangement is mounted inside the nacelle of the wind turbine. According to yet another preferred embodiment of the invention, some parts of the damper arrangement, one of the damper devices for example, are mounted inside the tower, whilst other parts of the damper arrangement, another damper device for example, are mounted inside the nacelle.

The damper arrangement according to the present invention comprises at least one, preferably two active damper device(s). Basically, it is sufficient according to the present invention that the damper arrangement solely comprises one single damper device. However, according to a preferred embodiment of the present invention, the damper arrangement specifically comprises two such damper devices. Nevertheless, according to other embodiments of the present invention, the damper arrangement may comprise three or more such damper devices as well without any limitations. In case that the damper arrangement comprises two or more damper devices it is preferred that each damper device can be operated individually and independently from the other damper devices. Furthermore, it is preferred that the damper devices are arranged at different locations of the wind turbine. Preferred embodiments with regard to this are described in more detail further below.

According to the present invention, active damper devices are used. In particular, such an active damper device is installed in an existing wind turbine, which means that the wind turbine is supplemented by this additional, individually adapted active damper device, said damper device being adapted to independently influence the vibration behaviour of the wind turbine.

It is the general function of the at least one damper device to compensate any vibrations induced on the wind turbine, on the tower and/or on the nacelle, for example. For this purpose, the damper arrangement and especially the damper device(s) is/are configured in a very specific manner.

According to the present invention, each damper device comprises a mass. This mass serves to compensate the vibrations. Preferably, such a mass can have a weight of about six tons.

Furthermore, the damper device of the damper arrangement according to the present invention comprises a guiding device, to which the mass is movably connected. By means of this guiding device, the mass is moved or can be moved along the guiding device. Preferably, the mass can be freely moved along the guiding device. In particular, the guiding device forces the mass to move in a certain path which is pre-set by said guiding device. In particular, the guiding device is provided as an elongated member, which means that the guiding device has a length which is a multiple of its width. The guiding means has an extension direction, which, in particular, corresponds to the longitudinal extension of the guiding device. Since the mass is movably connected to the guiding device, the mass can be freely moved along the guiding device, in particular along the elongated guiding device, preferably back and forward in the extension direction of the guiding device. According to a preferred embodiment, the guiding device can be provided in such a way that the mass is adapted of performing a linear movement along the guiding device.

The present invention is not limited to specific types or configurations of such guiding devices. In preferred embodiments, the guiding device is provided as or comprises a guiding rail or a guiding rod or a toothed rack, or the guiding device is provided as or comprises a guiding beam element, in particular an I-shaped guiding beam element, or the guiding device is provided as or comprises a guiding beam element having a guiding rail or guiding rod or toothed rack being mounted thereto.

According to the present invention, the mass is movably connected to the guiding device by means of a drive. In particular, the drive is some kind of mechanism that imparts a motion to the mass. It is the general function of said drive, that it is adapted to move the mass along the guiding device in the extension direction thereof.

The present invention is not limited to specific types of drives. According to a preferred embodiment, the drive comprises a drive motor, in particular an electric motor.

Furthermore, the drive may comprise a gear device. It is the general function of such a gear device, that the forces generated by said drive, the torque of a drive motor for example, are transferred into a movement along the guide device.

According to a preferred embodiment, the damper device comprises a mass that is movably connected to a guiding device, in particular to a guiding beam element, an I-shaped guiding beam element for example, by means of a drive, said drive comprising an electric motor and a gear device, said gear device comprising a toothed drive wheel, which engages a toothed rail being fixed to or being part of the guiding device.

According to the present invention, the drive of the damper device is a portion of the mass. That means, if the drive comprises a drive motor, the drive motor is a portion of the mass. Furthermore, if a gear device is used, it is preferred that the gear device is a portion of the mass as well. According to the present invention the mass of each of the damper devices firstly comprises the mass body itself. The mass body can be provided as one single monolithic component. According to a different embodiment, the mass body may be divided into a number of mass body elements, two mass body elements for example. In the latter case the individual mass body elements are connected to each other such that all mass body elements in total form the mass body. Furthermore, in addition to the mass body, the mass comprises the drive, preferably the drive motor and optionally the gear device as well, such that the weight of the drive can be added to the weight of the mass body. In this case, the weight of the mass body per se can be reduced, since the weight of the drive, in particular the weight of the drive motor and optionally of the gear device are added to the overall weight of the movably mass, since they move together with the mass body along the guiding device.

In a preferred embodiment, the mass is evenly distributed by weight above and below said guiding device. That means that this portion of the mass which extends above the guiding device has the same weight as this portion of the mass which extends below the guiding device. In such a case, the mass preferably comprises a mass body consisting of two mass body elements, one mass body element being arranged and therefore extending above the guiding device, and one mass body element being arranged and thereby extending below the guiding device. By use of such a configuration any negative forces or moments can be avoided.

According to a preferred embodiment, the damper arrangement comprises two damper devices. In this case it is preferred, that the damper devices are spatially spaced from each other. Preferably, both damper devices can be provided in different planes or levels, in particular when mounted to the wind turbine, inside the wind turbine for example. According to yet another preferred embodiment, the guiding devices of the damper devices are provided in different planes or levels, in different horizontal planes or levels for example.

According to yet another preferred embodiment, the damper arrangement comprises two damper devices, whereby the guiding devices of the damper devices are offset by a defined angle in their extension directions. That means that the masses of both damper devices each move in different directions in comparison to each other, namely in a direction offset by the defined angle. According to a preferred embodiment, the guiding devices of the damper devices are offset by an angle of 90 degrees in their extension directions. Due to this configuration the entire plane or extension or area inside the wind turbine, inside the tower for example, can be reached and therefore covered by the movement of the masses of the damper devices.

When the damper arrangement is arranged inside the wind turbine, the tower and/or the nacelle for example, it is a typical problem, that the installation space being available for the damper arrangement is very restricted, since other components of the wind turbine are already arranged inside the wind turbine as well. In order to meet with such limited space conditions, the damper arrangement is split into a number of individual components, into two or more individual damper devices for example. Each damper device comprises a mass that is movably connected to a guiding device. Preferably each guiding device pre-sets the movement direction of the mass being mounted thereto. In order to cover all movement directions, in particular in the horizontal direction, the guiding devices of each damper device are offset in a pre-defined angle in relation to each other, in an angle of 90 degrees for example. Thus, the guiding devices do not block the entire installation space, the entire cross-section of the tower for example, but only a portion thereof. According to a preferred embodiment, when the damper arrangement comprises two damper devices, each damper device comprising a guiding device, the guiding devices can be arranged such that they cover an L-shaped area. When using two or more damper devices as described before, sufficient installation space inside the wind turbine, specifically inside the tower and/or the nacelle remains for picking up different components of the wind turbine, for example a cable loop, a ladder or the like.

According to a preferred embodiment, the damper arrangement comprises two damper devices, whereby the masses of each damper device are connected to the respective guiding devices such, that they are moved or that they can be moved independently from each other.

According to a preferred embodiment, the damper arrangement comprises at least one vibration sensor. In general, it is sufficient that only one single vibration sensor is provided. However, according to a preferred embodiment, two or more such vibration sensors are provided. The vibration sensor(s) is/are mounted to the wind turbine, preferably at different locations. The vibration sensor generates vibration values with regard to the wind turbine, with regard to the tower and/or to the nacelle for example. Generating vibration values particularly means that the vibration sensor detects such values or that the vibration sensor computes or estimates such values.

According to yet another preferred embodiment, the damper arrangement comprises at least one control device, said control device(s) being adapted for controlling the damper device(s), in particular the drive(s) of the damper device(s). According to a preferred embodiment, one single control device is provided which controls all of the damper devices, in particular each drive of each damper device. In such a case the control device may be part of the central control unit of the wind turbine. According to a different embodiment, each damper device comprises its own control device.

When using at least one control device it is preferred that the at least one vibration sensor is allocated to said at least one control device. According to another preferred embodiment the at least one control device comprises an interface to said at least one vibration sensor, said interface being adapted for receiving vibration values being transmitted from said at least one vibration sensor.

In the following, a preferred embodiment of the damper arrangement according to the first aspect of the invention will be explained in more detail. According to this preferred embodiment, the damper arrangement comprises two damper devices, each damper device comprising a mass. Each mass can be moved in only one direction which is pre-set by the alignment of the elongated guiding devices. Generally, each mass can be moved back and forward along its guiding device in the extension direction thereof. The guiding devices of both damper devices are aligned in an angle of 90 degrees to each other. The damper devices are located at different levels. Each damper device comprises a mass body comprising one or more mass body elements, which is connected to a drive, a drive motor including a gear device for example. This mass unit, which comprises the mass body and the drive, moves along the guiding means, a guiding beam for example, to which a guiding rail or a toothed rack is mounted. Therefore, the damper arrangement includes two drives, particularly two electrical drives, which are adapted for actively controlling and moving the masses. The damping arrangement is mounted on guiding beams with a rail system on different levels. The, preferably electrical, drives move in the direction offset by 90 degrees. Both masses can be moved independently from each other to compensate tower vibrations.

According to the second aspect of the invention, a wind turbine is provided, said wind turbine comprising a tower and a nacelle being mounted at the top of the tower, said wind turbine further comprising a drive train being mounted inside said nacelle and a rotor including a number of rotor blades, said rotor being pivotally mounted around a rotational axis to the drive train. The wind turbine is characterized in that the wind turbine comprises a damper arrangement which is provided according to the first aspect of the invention, said damper arrangement being provided inside the wind turbine, preferably inside the tower and/or inside the nacelle.

With regard to the construction and the function of the wind turbine and its components, full reference is also made to the description further above, in particular to the first aspect of the invention as disclosed above, as well as to the description of the underlying concept of the present invention. In particular, the wind turbine comprises one or more features as described in detail further above. Furthermore, full reference is also made to the method according to the third aspect of the present invention which will be described further below.

According to this second aspect of the invention the wind turbine comprises a damper arrangement, which is preferably mounted inside the wind turbine, inside the tower and/or inside the nacelle for example.

According to a preferred embodiment, when mounted inside the tower, the guiding devices of each damper device can be mounted to the inner wall of the tower or to any components being provided inside the tower. In such a case the damper arrangement can be provided as some kind of a guide-rail-system which may be arranged in the top section of the tower. Two drives, each including a drive motor, an electric drive motor for example, and optionally a gear device and an additional mass body comprising one or more, preferably two, mass body elements, which makes in sum two additional masses, are mounted on an elongated guiding device, a guiding beam with a rail system for example, on different levels inside the tower. Each drive moves in the direction offset by 90 degrees in comparison to the other drive. Both masses can be moved independently from each other in order to compensate tower vibrations.

According to another preferred embodiment, the damper arrangement is provided inside the nacelle. In such a case, the damper arrangement can be provided as some kind of a guide-rail-system below the main frame or the main girder system or beam of the nacelle. In general, the latter components carry the drive train of the wind turbine. Two drives, each including a drive motor, an electric drive motor for example, and optionally a gear device and an additional mass body, which makes in sum two additional masses, are mounted on an elongated guiding device, a guiding beam with a rail system for example, on different planes or levels inside the nacelle. Each drive moves in the direction offset by 90 degrees in comparison to the other drive. Both masses can be moved independently from each other in order to compensate tower vibrations.

Preferably, the damper arrangement comprises two damper devices, whereby the damper devices are provided spatially spaced apart from each other, preferably in different levels or planes.

According to the third aspect of the invention, a method of damping vibrations of a wind turbine by making use of a damping arrangement according to the first aspect of the invention is provided, wherein at least one vibration sensor, which is allocated to said wind turbine, generates vibration values, wherein the at least one vibration sensor transmits the vibration values to a control device of at least one damper device of the damper arrangement, said control device being connected to the drive of said at least one damper device, and wherein, based on the received vibration values the control device controls the drive of the damper device such that the mass of said damper device is moved, by means of said drive, along the guiding device of said damper device in the extension direction thereof, in order to compensate vibrations of the wind turbine.

With regard to the performance and to the function of the method and its different steps, full reference is also made to the description further above, in particular of the first aspect of the invention as disclosed further above, to the second aspect of the invention as disclosed further above, as well as to the description of the underlying concept of the present invention.

According to the method of the invention, the vibration sensor measures the vibrations of the wind turbine, for example any vibrations of the tower and/or if the nacelle. The vibration sensor delivers its data in form of vibration values to at least one control device, which control(s) and actuate(s) the drives of each damper device and which moves the masses in such a way that the masses can counteract on the vibrations of the wind turbine.

The present invention according to its three aspects has a number of advantages, which are particularly as follows:
- The masses can be mounted in a space saving manner, besides or surrounding the cable loop or the ladder for example:
- A cable loop or a ladder being provided inside the tower does not have to be changed or modified;
- The efficiency of the masses can be increased;
- The weight of the drives, the drive motors and the gear devices for example, can be added to the overall weight of the masses, since they get moved together with the mass bodies themselves, therefore the required flywheel mass can be reduced;
- For moving the masses only two drive motors are required. Any additional equipment like additional actuators or hydraulic components are not required anymore;
- The damper arrangement according to the invention can be preferably used where only a limited installation space is available.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail with respect to exemplary embodiments with reference to the enclosed drawings, wherein:

Figure 1 shows a diagrammatic view of an exemplary wind turbine;
Figure 2 shows a schematic representation of the damper device of a damper arrangement according to the present invention;
Figure 3 shows different representations of a first embodiment of the present invention, wherein the damper arrangement is provided inside the tower of the wind turbine;
Figures 6 to 9 show different representations of a second embodiment of the present invention, wherein the damper arrangement is provided inside the tower of the wind turbine; and
Figures 10 to 12 show different representations of a third embodiment of the present invention wherein the damper arrangement is provided inside the nacelle of the wind turbine.

DESCRIPTION OF THE INVENTION

Figure 1 shows a wind turbine 10 of the horizontal type with a tower 12 and a nacelle 11. Nacelle 11 is rotatable mounted to the top of tower 12. At its lower base end, the tower 12 is anchored to the ground by means of a foundation 16. Nacelle 11 incorporates a drive train (not shown), said drive train being mounted inside nacelle 11 and being connected to a rotor 13. Rotor 13 comprises three rotor blades 15 which are mounted to a hub 14. Hub 14 of rotor 13 is connected to a drive shaft of the drive train. The rotor blades 15 are adjustably mounted on the hub 14. This is realized by means of pitch drives, said pitch drives being part of a pitch system. The pitch system controls the rotor speed to given set points. By means of pitch-drives, the rotor blades 15 may be moved about a rotor blade axes into different pitch positions. The rotor 13 is rotatably connected to the drive train via its rotational axis.

The drive train transmits the rotor speed to a generator device, where it is converted into electric energy. In order to transform the rotational energy of the rotor 13 into electric energy, the drive train, to which the rotor 13 of the wind turbine 10 is mounted, comprises a gear device. At its entrance side, the gear device is connected to the rotor 13 via a drive shaft (not shown), a slow running drive shaft for example. The rotor 13 is connected to said drive shaft via its rotor hub 14. On its exit side, the gear device comprises an output shaft, a fast running output shaft for example. The gear device has the function to transform the low speed or low revolution and the high torque of the drive shaft into a high speed or high revolution and a small torque of the output shaft. The gear device is connected to the generator device. In particular, the output shaft of the gear device is coupled to a generator shaft of the generator device. The generator device generates electric energy from the rotational energy which is provided by the gear device. For this purpose, the generator device preferably comprises a stator component and a rotor component, said rotor component being coupled to the generator shaft.

The wind turbine depicted in Figure 1 may reach an overall height of more than 100 metres. Since the wind turbine 10 comprises a slender structure, and since the nacelle 11 including the rotor 13 with its rotor blades 15 is provided at the top of the tower 12, the wind turbine 10 provides a lot of contact surface for the wind. If the wind hits the wind turbine 10, the wind turbine 10, especially the tower 12, the rotor 13 with its rotor blades 15 and the nacelle 11 are exposed to vibrations. Such vibrations can have high amplitudes. However, these vibrations negatively influence the performance of the wind turbine. Additionally, negative vibrations are also generated by forces induced on the nacelle 11 and the tower 12 by the rotating rotor blades 15.

In order to compensate such vibrations, the wind turbine comprises a damper arrangement 20 which will now be explained in more detail in connection with Figures 2 to 12. Figure 2 shows the general construction of such a damper arrangement 20 according to a preferred embodiment thereof.

According to this preferred embodiment, the damper arrangement 20 comprises a damper device 21, which comprises a mass 22. The mass 22 comprises a mass body 30. The mass body 30 can be moved in only one direction which is pre-set by the alignment of an elongated guiding device 23. The mass body 30 can be moved back and forward along its guiding device 23 in the extension direction thereof. The mass body 30 is connected to a drive 24, said drive 24 including a drive motor 25 and a gear device 26. This mass 22, which comprises the mass body 30 and the drive 24, moves along the guiding device 23, a guiding I-beam for example, to which a guiding rail 27 is mounted. The guiding rail 27 comes in contact with a corresponding toothed drive wheel 28, which is part of the drive 24. By means of gear device 26, drive wheel 28 and guiding rail 27, the torque generated by drive motor 25 is transferred into a longitudinal moving force. In order to support this construction, the damper device 21 may comprise additional bearings 29.

In order to sufficiently compensate any vibrations, the damper arrangement 20 comprises two such damper devices 21, which will now be explained with regard to Figures 3 to 12 which depict three different but preferred embodiments of the damper arrangement 20 according to the present invention. In the following, identical members of the damper arrangement 20 which are identical in the different embodiments, are depicted with identical reference numerals respectively. Therefore, any statements made to such identical members with regard to one of the embodiments apply to their full extent to the other embodiments as well.

According to all of the embodiments, the damper arrangement 20 includes two damper devices 21 with two drives 24, particularly two electrical drives, which are adapted for actively controlling and moving the masses 22. The damper devices 21 are mounted on guiding devices 23 with guiding rails 27 on different levels. The, preferably electrical, drives 24 move the masses 22 in a direction offset by 90 degrees. Both masses 22 can be moved independently from each other to compensate tower vibrations.

Figures 3 to 9 are directed to a first and a second embodiment of the present invention, wherein the damper arrangement 20 with its two damper devices 21 is mounted inside the tower 12. Therefore, any statements made with respect to the first embodiment also apply to their full extent to the second embodiment, and vice versa.

Figures 3 to 5 depict different views of the first embodiment of the present invention. The guiding devices 23 of each damper device 21 may be mounted to the inner wall of the tower 12 or to any components being provided inside the tower 12. Both drives 24, each including a drive motor, an electric drive motor for example, and optionally a gear device and an additional mass body 30, which makes in sum two additional masses 22, are mounted on the elongated guiding devices 23, a guiding beam with a rail system for example, on different levels inside the tower 12. Each drive 24 moves in the direction offset by 90 degrees in comparison to the other drive. Both masses 22 can be moved independently from each other in order to compensate tower vibrations.

When the damper arrangement 20 is arranged inside the tower 12, the installation space being available for the damper arrangement 20 is very restricted, since other components of the wind turbine 10, a cable loop 17 and a ladder 18 for example, are arranged inside the tower 12 as well. In order to meet with such limited space conditions, the damper arrangement 20, is split into two damper devices 21. Each damper device 21 comprises a mass 22 that is movably connected to guiding device 23. Each guiding device 23 pre-sets the movement direction of the mass 22 being mounted thereto. In order to cover all movement directions, the guiding devices 23 of each damper device 21 are offset in a pre-defined angle in relation to each other, in an angle of 90 degrees for example. Thus, the guiding devices 23 do not block the entire cross-section of the tower 12, but only a portion thereof. The guiding devices 23 are arranged such that they cover an L-shaped area. Thus, sufficient installation space inside the tower 12 remains for picking up different components of the wind turbine 10, for example a cable loop 17, a ladder 18 or the like.

Figures 6 to 9 depict different views of the second embodiment of the present invention, wherein the damper arrangement 20 with its two damper devices 21 is mounted inside the tower 12. However, for illustrative purposes, only one damper device 21 is depicted in detail in Figures 6 to 9. Figure 6 represents a side view, Figure 7 represents a front view, whilst Figure 8 depicts a detailed view of the damper device 21; and Figure 9 depicts a detailed view of the guiding device 23 of the damper device 21.

In Figures 6 to 9, only the interior of tower 12 without any tower walls is depicted. However, one can see the cable loop 17 and a ladder 18 being installed in the centre of the tower 12.

The damper arrangement 20 is configured in a similar manner as described with regard to the first embodiment. Therefore, at this point, full reference is made to the disclosure of the first embodiment.

According to the second embodiment as shown in Figures 6 to 9, the mass body 30 of mass 22 comprises two mass body elements 31, 32. In this embodiment, the mass 22, which consists of the mass body 30 and the drive 24 with its drive motor 25 and its gear device 26, is evenly distributed by weight above and below said guiding device 23. That means that the portion of the mass 22 which extends above the guiding device and which comprises the first mass body element 31 and the drive 24, has the same weight as the portion of the mass 22, which extends below the guiding device 23 and which comprises the second mass body element 32. Further, since the drive 24 is arranged near to the guiding device 23, both mass body elements 31, 32 may have the same weight. According to the second embodiment, the mass 22 comprises a mass body 30 consisting of two mass body elements 31, 32, one mass body element 31 being arranged and therefore extending above the guiding device 23, and one mass body element 32 being arranged and therefore extending below the guiding device 23.

As can be derived from Figures 8 and 9, the damper device 21 is configured similar to the damper device 21 in the embodiment described with regard to Figure 2, such that full reference is made to the description of Figure 2 as well. As evident form Figures 8 and 9, the damper device 21 of damper arrangement 20 comprises a mass 22. The mass 22 comprises a mass body 30 consisting of two mass body elements 31, 32. The mass body 30 can be moved along guiding device 23 in a backward and forward direction in the extension direction of guiding device 23. The mass body 30 is connected to a drive 24, said drive 24 including a drive motor 25 and a gear device 26. This mass 22, which comprises the mass body 30 with its mass body elements 31, 32 and the drive 24, moves along the guiding device 23, a guiding I-beam for example, to which a toothed guiding rail 27 is mounted. The guiding rail 27 comes in contact with a corresponding toothed drive wheel 28, which is part of the drive 24. By means of gear device 26, drive wheel 28 and guiding rail 27, the torque generated by drive motor 25 is transferred into a longitudinal moving force. In order to support this construction, the damper device 21 may comprise additional bearings 29.

Figures 10 to 12 depict different views of the third embodiment of the present invention, where the damper arrangement 20 with its two damper devices 21 is mounted inside the nacelle 11.

According to this embodiment, the damper arrangement 20 is provided inside the nacelle 11. In this a case, the damper arrangement 20 can be provided below the main frame or the main girder system or beam of the nacelle 11, which carries the drive train (not shown) of the wind turbine. Both drives 24 of each damper device 21 of damper arrangement 20, each drive 24 including a drive motor, an electric drive motor for example, and optionally a gear device and the additional mass body 30, which makes in sum two additional masses 22, are mounted on the elongated guiding devices 23, a guiding beam with a rail system for example, in different planes or levels inside the nacelle 11. Each drive 24 moves in the direction offset by 90 degrees in comparison to the other drive. Both masses 22 can be moved independently from each other in order to compensate tower vibrations.
,CLAIMS:CLAIMS

We Claim:

Claim 1. A damper arrangement (20) for damping vibrations of a wind turbine (10), said damper arrangement (20) comprising: at least one, preferably two active damper device(s) (21), each damper device (21) comprising a mass (22) and a guiding device (23), to which the mass (22) is movably connected by means of a drive (24), said guiding device (23) having an extension direction, said drive being adapted for moving the mass along the guiding device (23) in the extension direction thereof, said drive (24) being a portion of said mass (22).

Claim 2. The damper arrangement according to claim 1, characterized in that the guiding device (23) is provided as or comprises a guiding rail (27) or a guiding rod or a toothed rack, or that the guiding device (23) is provided as or comprises a guiding beam element, in particular an I-shaped guiding beam element, or that the guiding device (23) is provided as or comprises a guiding beam element having a guiding rail or guiding rod or toothed rack being mounted thereto.

Claim 3. The damper arrangement according to claim 1 or 2, characterized in that the drive (24) comprises a drive motor (25), in particular an electric motor.

Claim 4. The damper arrangement according to any one of claims 1 to 3, characterized in that the drive (24) comprises a gear device (26).

Claim 5. The damper arrangement according to any one of claims 1 to 4, characterized in that the mass (22) is evenly distributed by weight above and below said guiding device (23).

Claim 6. The damper device according to any one of claims 1 to 5, characterized in that the damper arrangement (20) comprises two damper devices (21), the damper devices (21) being spatially spaced from each other.

Claim 7. The damper arrangement according to any one of claims 1 to 6, characterized in that the damper arrangement (20) comprises two damper devices (21), the guiding devices (23) of the damper devices (21) being provided in different planes or levels.

Claim 8. The damper arrangement according to any one of claims 1 to 7, characterized in that the damper arrangement (20) comprises two damper devices (21), and that the guiding devices (23) of the damper devices (21) are offset by a defined angle in their extension directions, in particular by an angle of 90 degrees.

Claim 9. The damper arrangement according to any one of claims 1 to 8, characterized in that the damper arrangement (20) comprises two damper devices (21) and that the masses (22) of each damper device (21) are connected to the respective guiding devices (23) such that they are moved independently from each other.

Claim 10. The damper device according to any one of claims 1 to 9, characterized in that the damper arrangement (20) comprises at least one vibration sensor.

Claim 11. The damper arrangement according to any one of claims 1 to 10, characterized in that the damper arrangement (20) comprises at least one control device, said control device(s) being adapted for controlling the damper device(s) (21), in particular the drive(s) (24) of the damper device(s) (21).

Claim 12. The damper arrangement according to claim 11 as far as referred to claim 10, characterized in that the at least one vibration sensor is allocated to said at least one control device, or that the at least one control device comprises an interface to said at least one vibration sensor, said interface being adapted for receiving vibration values being transmitted from said at least one vibration sensor.

Claim 13. A wind turbine (10), said wind turbine (10) comprising a tower (12) and a nacelle (11) being mounted at the top of the tower (12), said wind turbine (10) further comprising a drive train being mounted inside said nacelle (11) and a rotor (13) including a number of rotor blades (15), said rotor (13) being pivotally mounted around a rotational axis to the drive train, characterized in that the wind turbine (10) comprises a damper arrangement (20), which is provided according to any one of claims 1 to 12, said damper arrangement (20) being provided inside the wind turbine (10), preferably inside the tower (12) and/or inside the nacelle (11).

Claim 14. The wind turbine according to claim 13, characterized in that the damper arrangement (20) comprises two damper devices (21), and that the damper devices (21) are provided spatially spaced from each other.

Claim 15. A method of damping vibrations of a wind turbine according to any one of claims 13 or 14 by making use of a damping arrangement according to any one of claims 1 to 12, wherein at least one vibration sensor, which is allocated to said wind turbine, generates vibration values, wherein the at least one vibration sensor transmits the vibration values to a control device of at least one damper device of the damper arrangement, said control device being connected to the drive of said at least one damper device, and wherein, based on the received vibration values the control device controls the drive of the damper device such that the mass of said damper device is moved, by means of said drive, along the guiding device of said damper device in the extension direction thereof, in order to compensate vibrations of the wind turbine.

List of Reference Numerals
10 Wind turbine
11 Nacelle
12 Tower
13 Rotor
14 Hub
15 Rotor blade
16 Foundation
17 Cable loop
18 Ladder
20 Damper arrangement
21 Damper device
22 Mass
23 Guiding device
24 Drive
25 Drive motor
26 Gear device
27 Guiding rail
28 Drive wheel
29 Bearing
30 Mass body
31 First mass body element
32 Second mass body element