WO2011117081A2

WO2011117081A2 - Wind turbine and method of construction of a wind turbine

Info

Publication number: WO2011117081A2
Application number: PCT/EP2011/053659
Authority: WO
Inventors: Finn Kjaergaard; Jesper Munch
Original assignee: Siemens Aktiengesellschaft
Priority date: 2010-03-26
Filing date: 2011-03-11
Publication date: 2011-09-29
Also published as: US20130011273A1; US9759190B2; CN102812236B; EP2553261A2; WO2011117081A3; CN102812236A

Abstract

The invention concerns a wind turbine (1', 1'') with a nacelle (5) and a rotor (8), the rotor (8) comprising a number of blades (10) and a hub (7), the nacelle (5) and the hub (7) being connected with each other in an interface region (17), the wind turbine further comprising a transport system (20) for transporting hydraulic and/or pneumatic fluid from the nacelle (5) into the hub (7). The transport system (20) comprises a rotary unit (13) as a connection through which the fluid passes and a part of which rotates in operation together with the hub (7) which rotary unit (13) is positioned in the hub (7) at a position distanced from the interface region (17) facing away from the nacelle (5), the transport system (20) further comprising a pipe system (11) leading from the interface region (17) into the hub to the rotary unit (13) and being fixed in its position. The invention also concerns a method of construction of such wind turbine (1', 1'').

Description

Wind turbine and method of construction of a wind turbine Field of the invention

The invention relates to a wind turbine with a nacelle and a rotor, the rotor comprising a number of blades and a hub, the nacelle and the hub being connected with each other in an in^¬ terface region, the wind turbine further comprising a trans- port system for transporting hydraulic and/or pneumatic fluid from the nacelle into the hub. The invention also relates to a method of construction of such a wind turbine.

Background of the invention

Today's wind turbines, in particular large scale wind tur^¬ bines with power outputs in the scale of above 1 MW, are very complex systems. Despite their large size, their operational state needs to be adaptable to current weather conditions, in particular wind conditions. For that purpose, the position of the rotor blades of the rotors of such wind turbines can be adapted. A so-called pitch control system allows for posi^¬ tioning the rotor blades against the wind by rotating the blades around their longitudinal axis. Thus, the rotational speed of the rotor can be controlled and a maximum power out^¬ put can be achieved.

The usual way of pitch control of the rotor blades is by us- ing an electric pitch control system in which electric engines control the pitch of the blades. However, it has been wished for to use hydraulic pitch systems (or pneumatic pitch systems - which are also summarized under the expression "hy^¬ draulic pitch system" in the context of this application) rather than electric ones. Such hydraulic systems are often easier to control and they also still function in the case of an interruption of power output of the generator of the wind turbine because they are not directly dependent on electric power supply by the wind turbine itself. In order to drive such hydraulic pitch systems it is necessary to have a trans^¬ port system which transports a hydraulic and/or pneumatic fluid (such as hydraulic oil, water or any other liquid or gas) into the pitch control system in the hub under a certain pressure. In other words, the hydraulic and/or pneumatic fluid is put under a certain pressure by means of a pump and lead to a distribution block, to blade blocks and accumulator blocks which are all located inside the hub in close prox^¬ imity to the rotor blades.

The transport of this pressurised hydraulic and/or pneumatic fluid, however, has proven to be quite complicated. This is due to the fact that the hub rotates in operation of the wind turbine so that a solution has to be found of how the pipes of the transport system are not rotated together with the hub in such a way that they will be damaged due to torsions.

Summary of the invention

It is therefore an object of the invention to provide a pos^¬ sibility of supplying and/or operating a wind turbine with an enhanced transport system for transporting hydraulic or penaumatic fluid from the nacelle into the hub of the wind turbine. One particular object of the invention is also to provide such a transport system which poses a minimum obsta^¬ cle to staff who want to enter the hub from the nacelle for purpose of maintenance and/or assembly of the wind turbine. The objects of the invention are achieved by a wind turbine according to claim 1 and by a method according to claim 10.

Accordingly, a wind turbine of the above-mentioned kind is realized such that the transport system comprises a rotary unit as a connection through which the fluid passes and a part of which rotates in operation together with the hub which rotary unit is positioned in the hub at a position dis^¬ tanced from the interface region facing away from the na- celle, the transport system further comprising a pipe system leading from the interface region into the hub to the rotary unit and being fixed in its position

Rotary units can be characterized as construction elements of a transport system with a stationary (or non-rotatable) part and a rotatable (or non-stationary) part connected to each other in such way that the rotating part can rotate around a predefined rotation axis. The connection between the stationary part and the rotatable part is such that essentially no hydraulic and/or pneumatic fluid passes from the inside of the rotary unit to its outside, i.e. the inner side of the rotation unit is isolated such that it prevents a leakage. When fluid is led into the inside of the stationary part it will pass into the inside of the rotatable part and from there into other (stationary or non-stationary) parts of the transport system. The fluid can also be led into the ro^¬ tatable part and pass into the stationary part. The fluid passes from the nacelle into the hub, but it can possibly also be led back into the opposite direction if needed. For instance, a pump situated in the nacelle can pump the fluid via the rotary unit into a hydraulic pitch system in the hub. The fluid may also be led back into the nacelle, for example into a reservoir in the nacelle. The invention makes use of such a rotary unit which is spe^¬ cifically positioned in the hub at a position distanced from the interface region facing away from the nacelle. Such an interface region is situated at the inside of the wind tur- bine as a transition area in which both the nacelle and the hub end and which can thus be assigned either to the nacelle or to the hub, but not clearly to any of both. The nacelle forms a first cavity, the space surrounded by the direct drive generator forms a second cavity and the hub forms a third cavity. The interface region is located where the sec^¬ ond cavity is connected to the third cavity. The interface region is normally used in order to get from the nacelle into the hub which implies that an average sized adult man can travel through the cavities. No main functional elements of the wind turbine are situated in the cavities in the inter^¬ face region. Such functional parts are in particular the ro^¬ tor, the pitch system, or the generator. In the case of a direct drive wind turbine (which will be described in detail below) the generator can be assembled around the interface region, i.e. not in the interface region itself, but sur^¬ rounding it. Generally, the interface region can be derived from the outside limits of the nacelle facing in the direc^¬ tion of the hub. The outside limits of the nacelle are best defined by the limits of its outer shell, the so-called can- opy. These limits define a plane extending through the inside of the wind turbine. From this plane to either side into the nacelle and into the hub the interface region extends not more than 0,3 metres. In other words, the rotary unit is positioned inside of the hub, i.e. away from the nacelle on the other side of the in^¬ terface region. Due to this positioning the rotary unit does not stand in the way of operations either within the nacelle or in the interface region through which staff want to pass without being hindered by any objects such as the rotary unit .

Such positioning also has the advantage that the stationary part of the rotary unit is connected to the nacelle whereas the rotatable part of the rotary unit can be directly con^¬ nected to the hub, in particular to the pitch system within the hub. Thus the stationary part of the wind turbine, i. e. the nacelle, is connected to the stationary part of the ro- tary unit, whereas the rotatable part of the wind turbine, i. e. the hub, is connected to the rotatable part of the rotary unit. The functions of the parts of the rotary unit match with the functions of the nacelle and of the hub respec^¬ tively. Positioning the rotary unit in the hub means that it is placed at the very location in which the hydraulic fluid is needed, i.e. as close as possible to the pitch system. It is for that reason that staff working in the inside of the wind turbine can freely pass into the hub without being hin^¬ dered by a rotary unit. This is particularly so in a direct drive wind turbine: from the rotating hub some parts project into the nacelle. These parts carry a rotor of a generator which is surrounded by (or which surrounds) stator coils of this generator. This stator is carried by the nacelle. Thus, the region of the interface between the hub and the nacelle is essentially hollow so that persons can pass from the na^¬ celle into the hub easily. In this case, the drive train com^¬ prises those parts which project from the hub into the na^¬ celle and which are essentially formed pipe-like. Therefore, such drive train in a direct drive wind turbine can also be characterized as a communication link or communication assembly in contrast to drive trains in an indirect drive wind turbine (where the drive train comprises a number of shafts) . In the cavity formed by this pipe-like arrangement, a rotary unit could hinder staff from safely entering the hub or from returning back to the nacelle from the hub if the rotary unit is positioned in the interface region or further in the na^¬ celle. The positioning of the rotary unit in the hub prevents such problems effectively.

A method of construction of a direct drive wind turbine ac^¬ cording to the invention includes the steps of equipping the transport system with a rotary unit as a connection through which the fluid passes and a part of which rotates in opera- tion together with the hub, which rotary unit is positioned in the hub at a position distanced from the interface region facing away from the nacelle, and whereby a transport system is installed which further comprises a pipe system leading from the interface region into the hub to the rotary unit and which is fixed in its position so that it is not rotated dur^¬ ing operation of the rotary unit.

Particularly advantageous embodiments and features of the in^¬ vention are given by the dependent claims, as revealed in the following description. Thereby, features revealed in the con^¬ text of the wind turbine may also be realized in the context of any of the methods according to the invention and vice versa . The invention can generally be used in any kind of wind tur^¬ bine, be it a direct drive wind turbine or an indirect drive wind turbine: in a so-called indirect drive wind turbine a drive train, i.e. a rotatable shaft, is led along the axis of rotation of the hub into the inside of the nacelle. The drive train will then be led into a gearbox and further from there into a generator. In contrast, in so-called direct drive wind turbines no gearbox is necessary, and from the rotating hub some parts project into the nacelle. These parts carry a ro^¬ tor of a generator which is surrounded by (or which sur- rounds) stator coils of this generator. This stator is carried by the nacelle. In such a case the region of the inter^¬ face between the hub and the nacelle is essentially hollow so that persons can pass from the nacelle into the hub easily. The drive train then comprises those parts which project from the hub into the nacelle and which are essentially formed pipe-like .

As the passage between the nacelle and the hub is occupied by the shaft in the case of an indirect drive train, the inven^¬ tion makes particular use in such wind turbines in which the passage in the interface region is completely free. Therefore it is preferred that the wind turbine according to the inven^¬ tion is realized as a direct drive wind turbine with a drive train directly connecting the rotor with a generator, i.e. with not gearbox and no connecting shaft passing in the mid^¬ dle of the interface region. In direct drive wind turbines all of the above-mentioned advantages of the invention can be used to their full extent which is why this embodiment is particularly preferred.

Such a fixing of the pipe system in its position within the hub can for instance be realized by a solid, rigid, non- flexible pipe which is affixed to an inside surface or an- other fixed element placed within the nacelle. The pipe then projects from the nacelle into the hub and is preferably sta^¬ ble enough to keep its position within the hub without any stabilizing elements. It is preferred, however, that the pipe system is fixed within the hub by means of a rail projecting from the nacelle into the hub. Such a rail is made of solid material with a sufficient stability to keep the pipe of the pipe system in its position during operation of a rotating hub. The pipe(s) of the pipe system is/are connected to this rail and thus led by the rail into the hub. The rail can pro- trude as far into the hub as to bridge the distance between the end of the nacelle, i.e. the interface region, and the hydraulic pitch system in the hub, for instance in the middle of the hub. The pipe is first guided along the rail and then can be led through free air to the rotary unit to which it is connected .

In such a case, the transport system may comprise pipes made of any material. Inflexible pipes such as metal pipes or pipes made of solid plastics may be used in particular in all those regions of the transport system which need to be pro^¬ tected from persons stepping onto them and/or from objects that might potentially injur them during operation or mainte^¬ nance of the wind turbine. However, the transport system may also comprise a flexible pipe (or hose) if a rail is used.

In a particularly preferred embodiment the rail extends from the nacelle to the rotary unit. This means that the rail goes right from the nacelle up to the rotary unit so that the pipe is supported along its entire way from the interface region to the rotary unit by the rail.

The rail can be realized as a straight rail with no curves, but it may also have a shape describing a turn of direction. For instance, the rail may be straight from the nacelle into the hub and then extend in a different direction within the hub, i.e. towards the pitch system. The rail can be made of any solid material allowing for sufficient stability to keep its position and shape during operation of the wind turbine, i.e. during rotation of the hub. For instance a metal rail or a rail made of solid plastics can be utilized.

Preferably the rail is equipped with a cavity in which a pipe of the pipe system is positioned. Such cavity can be realized by using a tubular or partly tubular, i.e. cylindrical or partly cylindrical rail. A cavity can however also be real^¬ ized by a rail having for instance an open cross-sectional shape (at least in parts along its longitudinal extension) such as a U-shape or a V-shape. In other words, the rail has a cross-sectional shape inside of which a pipe of the pipe system can be accommodated without an obvious necessity to further fixing the pipe to the rail. Another way of how to lead the pipe along the rail is to fix the pipe at least lo- cally along its longitudinal extension to the rail, for in^¬ stance by means of brackets and/or by means of adhesion.

In order to provide for a particularly stable and obstacle- free arrangement of the transport system within the wind tur- bine the rail can be fixed to the nacelle in such way that in the interface region it is situated closely to an inner sur^¬ face of the wind turbine. For instance, the rail can be fixed to a ceiling surface or to a floor surface or to a side wall of the nacelle in the region of the interface region so that staff wishing to pass from the nacelle into the hub will not be hindered by an obstacle posed by the rail itself.

As outlined above, it is particularly advantageous if the ro^¬ tary unit is directly connected to a hydraulic and/or pneu- matic pitch system in the hub. That means that the pitch sys^¬ tem for which the fluid is supplied is directly fed with that fluid by the rotary unit without any intermediate pipe or other elements of a transport system. The shortest and safest way possible to transport the fluid from the rotary unit into the pitch system is thus realized.

Preferably the direct drive wind turbine further comprises a pump situated in the nacelle which pump in operation provides for pressure of the fluid in the transport system. That im- plies that the pump which provides for sufficient pressure within the transport system is situated remotely from the hub, i.e. remote from the pitch system in the first cavity of the wind turbine. The pump is thus situated in that part of the wind turbine, i.e. the nacelle, in which several func^¬ tional parts of a similar kind as the pump itself would be positioned anyway. Such functional parts include control sys^¬ tems of the wind turbine or other parts which are integrated in housings and which are positioned in those spaces within the wind turbine where they can easily be maintained by staff without the need to enter the hub.

In contrast, positioning a pump in the hub itself would mean that the pump either stands in the way of operations in the hub or that it is connected to a part of the hub in such way that it will rotate together with the hub. That would mean that the power supply for the pump becomes very difficult. If one positioned the pump in the interface region that would mean that it Constitutes an obstacle for staff to enter the hub or to return from the hub into the nacelle. To sum up, positioning the pump and possibly a reservoir for the fluid inside of the nacelle is - under the given circumstances of the rotary unit being placed in the hub - a very good solu^¬ tion of how to operate the pump easily while not hindering staff at the same time.

As for the rotary unit, it is particularly advantageous to position its rotation axis at a rotation axis of a drive train connecting the rotor with a generator - or in other words of a rotation axis of the hub, i.e. of the rotor. Both rotation axes are thus the same so that the rotary unit does not need to rotate with a different orientation than the ro^¬ tation movement of the rotor itself. That way it can be real^¬ ized that the rotatable part of the rotary unit is rotated along the same rotation axis as the drive train whereas the stationary part can remain in its position all throughout the operation of the wind turbine. A particular advantageous way of how to realize this is to directly connect the rotary unit to the pitch system, which pitch system is then preferably positioned at the centre of rotation, i.e. the rotation axis of the rotor.

Other objects and features of the present invention will be- come apparent from the following detailed descriptions con^¬ sidered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for the purposes of illustration and not as a defini^¬ tion of the limits of the invention.

Fig. 1 shows partially sectional side view of a wind turbine according to the state of the art,

Fig. 2 shows details of a first embodiment of a wind turbine according to the invention,

Fig. 3 shows a view into the hub of the same wind turbine along line III - III in Fig. 2, Fig. 4 shows a side view of a rotary unit which can be used as an element of a transport system according to an embodi^¬ ment of the invention,

Fig. 5 shows a second embodiment of a wind turbine according to the invention.

In the drawings, like reference numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale. Detailed description of the invention

Fig. 1 shows a wind turbine 1 with a nacelle 5 and a rotor 8. The rotor 8 comprises a hub 7 and rotor blades (not shown) , which can be inserted into openings 9 within the hub 7. The nacelle 5 is positioned on top of a tower 3. At its inside it comprises inside sufaces 12, 14, i.e. a bottom floor 12 and a ceiling 14.

The wind turbine 1 is realized as a direct drive wind turbine 1 with a generator 22 which directly transfers the rotational energy of the rotation of the hub 7 into electrical energy. The generator 22 comprises a stator 21 and a generator rotor 19 which generator rotor 19 is moved rotatingly along bearings 25 relative to the stator 21 around a rotation axis A of the rotor 8. This rotation axis A therefore also constitutes the rotation axis A of a drive train which includes those parts of wind turbine 1 which project from the rotor 8 into the generator 22.

Due to the movement of the generator rotor 19 which is di^¬ rectly connected to the hub 7 electric current is induced in the windings of the stator 21 which electric current can then be transferred to users. Between the nacelle 5 and the hub 7 there is an interface region 17. This interface region 17 ex^¬ tends from a division line Dl which is defined by the outside limits of the nacelle 5 both into the nacelle 5 and into the hub 7 about 0,5 metres, in some cases less, for instance 0,2 metres (depending on the size of the wind turbine 1 in ques^¬ tion) . A strict definition of the interface region only includes the division line Dl itself in the inside of the wind turbine 1 as the interface region. In wind turbines according to the state of the art the posi^¬ tioning of the rotor blades, i.e. their pitch, is normally controlled by an electric pitch system. If one wishes to use a hydraulic pitch system instead a problem arises concerning the transport of the hydraulic or pneumatic fluid to the pitch system. The hydraulic pitch system is positioned at that end of the inside of the hub 7 which faces away from the nacelle 5. The transport of the hydraulic fluid needs to be done by means of transport system supported by a pump provid- ing the pressure within the transport system to feed the pitch system in the hub 7. Due to the movement of the rotor 8 such transport is particularly difficult as normal pipes of the transport system would quickly be twisted due to the ro^¬ tation movement of the rotor.

Figs 2 and 3 show a detailed view of a direct drive wind tur^¬ bine 1' according to an embodiment of the invention. Again, the wind turbine 1 ' comprises a rotor 8 and a nacelle 5 to which the rotor 8 is rotatably fixed so that it can be ro- tated along a rotation axis A. In the wind turbine 1' a hy^¬ draulic pitch system 30 is installed which controls the pitch of the rotor blades 10. In Fig. 3 it can be seen that the hy^¬ draulic pitch system 30 comprises an accumulator block 2 and three blade blocks 4 which are each connected to one of the rotor blades 10 in order to control their pitch. In the accu^¬ mulator block 2 the hydraulic fluid is collected and the blade blocks 4 adjust the position of the rotor blades 10 in^¬ duced by the pressure of the fluid. Directly connected with the accumulator block 2 there is a rotary unit 13 comprising a first (stationary) part 13a and rotatable (non-stationary) part 13b which rotates together with the hub 7 of the rotor 8. The rotary unit 13 will be described in more detail in the context of Fig. 4. In order to feed the rotary unit 13 with hydraulic fluid, in this case oil, a pipe system 11 is led from the nacelle 5 where a pump 15 is situated into the hub 7 to the first part 13a of the rotary unit 30. The pipe system 11 comprises a solid or rigid pipe which is further supported by a rail 6 underneath it. The rail 6 is firmly fixed to the nacelle 5 on an inside surface 12, namely on the bottom floor 12. The rail 6 thus runs along the bottom floor 12 and pro^¬ jects further into the cavity of the inside of the hub 7 of the rotor 8. The rail 6 therefore stabilizes the position of the pipe system 11 and holds the pipe system 11 in position within the hub 7.

As can be seen in Fig. 3 the pipe system 11 comprises a pipe of hollow shape lying upon the rail six and then projecting (cf. Fig. 2) up to the rotation axis A of the hub 7. The ro- tation axis A of the hub 7 is also the rotation axis B of the rotary unit 13. The pump 15, the pipe 11 supported by the rails 6 and the rotary unit 13 make up a transport system 20 for the hydraulic fluid. This way hydraulic fluid can flow from the pump 15 in the direction of the rotary unit 13 and back while staff can easily walk through the interface region 17 essentially without being hindered by any parts of the transport system 20 projecting into the passage.

Figure 4 depicts a more detailed side view of the rotary unit 13 with parts of the hydraulic pitch system 30 and parts of the transport system 20. As outlined before, the rotary unit 13 comprises a first stationary part 13a and a second ro^¬ tatable part 13b which rotates around the rotation axis B. The stationary part 13a is partially inserted into a cavity 16 in the rotatable part 13b and lead along a bearing 24 which also hermetically seals the connection between the first part 13a and the second part 13b. Into the rotary unit 13 there leads a pipe of the pipe system 11 which is sup^¬ ported by the rail 6 as outlined in the context of Figs. 2 and 3. From where the pipe of the pipe system 11 is connected to the first part 13a of the rotary unit 13 there is a chan^¬ nel 14 inside of the stationary part 13a leading into the di^¬ rection of the rotatable part 13b. This (first) channel 14 of the first part 13a leads into a second channel 18 in the ro^¬ tatable part 13b. This second channel 18b leads into the ac^¬ cumulator block 20 where hydraulic fluid is collected and led further into the direction of the blade blocks for adjusting the pitch of the rotor blades 10 (cf . Fig. 2 and 3) . Hydrau- lie fluid can thus be transported to and fro from the pump 15 (cf. Figs. 2 and 3) into the hydraulic pitch system 30 and back. Thereby, the rotation of the hub 7 and thus of the ro^¬ tatable part 13b of the rotary unit 13 does not prevent a safe flow of the fluid from the pump 15 into the pitch system 30 and back.

Figure 5 shows a second embodiment of a wind turbine 1 ' ' ac^¬ cording to the invention, again realized as a direct drive wind turbine 1 ' ' . In contrast to the embodiment shown in Figs. 2 and 3 no use is made of a rail 6, but rather the transport system 20 is mainly assembled in a ceiling area of the wind turbine 1' ' . The pump 15 is located close to the ceiling 14 of the nacelle 5 and the pipe system 11 is led along the ceiling part 14a of the cavity formed by the gen- erator 22, which cavity ends in the interface region 17 of the wind turbine 1' ' . The pipe system 11 is firmly fixed to the ceiling 14 and the ceiling part 14a. It comprises a rigid, solid pipe made of metal which is stable enough to hold itself in position and which describes an essentially linear way from the pump 15 into the hub 7 where it then turns slightly down into the direction of the rotary unit 13 situated diagonally below. An advantage of this embodiment can be seen in the fact that staff are not in danger of even stepping on a part of the transport system 20 so that one is even less hindered during passage of the interface region 17.

It may be understood that the transport system 20 may com- prise different elements and/or different outlays of ele^¬ ments, in particular concerning the pipes and the channels 14, 18 as well as the connections between rotatable parts and stationary parts. For instance, the pipe system 11 may also comprise plastic pipes and also (if sufficiently supported in critical regions, particularly the hub) flexible pipes rather than non-flexible, rigid ones.

Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and varia^¬ tions other than those mentioned could be made thereto with^¬ out departing from the scope of the invention.

For the sake of clarity, it is to be understood that the use of "a" or "an" throughout this application does not exclude a plurality, and "comprising" does not exclude other steps or elements .

List of Reference Signs

1, 1', 1'' wind turbine

3 tower

4 blade blocks

5 nacelle

6 rail

7 hub

8 rotor

9 openings

10 rotor blades

11 pipe system

12 inside suface - bottom floor

13 rotary unit

13a first (stationary) part

13b second, (rotatable, non-stationary) part

14 ceiling part

14 first channel

14 inside suface - ceiling

15 pump

16 cavity

17 interface region

18 second channel

19 generator rotor

2 accumulator block

20 transport system

21 stator

22 generator

24 bearing

25 bearings

30 hydraulic pitch system

A rotation axis

B rotation axis

Di division line

Claims

1. Wind turbine (1', 1'') with a nacelle (5) and a rotor (8), the rotor (8) comprising a number of blades (10) and a hub (7), the nacelle (5) and the hub (7) being connected with each other in an interface region (17), the wind turbine further comprising a transport system (20) for transporting hydraulic and/or pneumatic fluid from the nacelle (5) into the hub (7), whereby the transport system (20) comprises a rotary unit (13) as a connection through which the fluid passes and a part of which rotates in operation together with the hub (7) which rotary unit (13) is positioned in the hub (7) at a position distanced from the interface region (17) facing away from the nacelle (5), the transport system (20) further com- prising a pipe system (11) leading from the interface region (17) into the hub to the rotary unit (13) and being fixed in its position.

2. Wind turbine according to claim 1, realized as a direct drive wind turbine with a drive train directly connecting the rotor (8) with a generator (22) .

3. Wind turbine according to claim 1 or 2, whereby the pipe system (11) is fixed within the hub (7) by means of a rail (6) projecting from the nacelle (5) into the hub (7) .

4. Wind turbine according to claim 3, whereby the rail (6) extends from the nacelle (5) to the rotary unit (13) .

5. Wind turbine according to claim 3 or 4, whereby the rail (11) is equipped with a cavity in which a pipe of the pipe system (11) is positioned.

6. Wind turbine according to one of claims 3 to 5, whereby the rail (6) is fixed to the nacelle (5) in such way that in the interface region (17) it is situated closely to an inner surface (12, 14) of the nacelle (5) .

7. Wind turbine according to any of the preceding claims, whereby the rotary unit (13) is directly connected to a hy^¬ draulic and/or pneumatic pitch system (30) in the hub (7) .

8. Wind turbine according to any of the preceding claims, further comprising a pump (15) situated in the nacelle (5) which pump (15) in operation provides for an increased pres^¬ sure of the fluid in the transport system (20) .

9. Wind turbine according to any of the preceding claims, whereby the rotation axis (B) of the rotary unit (13) is po^¬ sitioned at a rotation axis (A) of a drive train connecting the rotor (8) with a generator (22) .

10. Method of construction of a wind turbine (1', 1'') with a nacelle (5) and a rotor (8), the rotor (8) comprising a num^¬ ber of blades (10) and a hub (7), the nacelle (5) and the hub (7) being connected with each other in an interface region (17), the wind turbine (1', 1'') further comprising a trans- port system (20) for transporting hydraulic and/or pneumatic fluid from the nacelle (5) into the hub (7), whereby the transport system is equipped with a rotary unit (13) as a connection through which the fluid passes and a part of which rotates in operation together with the hub (7), which rotary unit (13) is positioned in the hub (7) at a position dis^¬ tanced from the interface region (17) facing away from the nacelle (5), and whereby a transport system (20) is installed which further comprises a pipe system (11) leading from the interface region (17) into the hub (7) to the rotary unit (13) and which is fixed in its position.