DK177158B1

DK177158B1 - Run-up deflector for an off-shore wind turbine

Info

Publication number: DK177158B1
Application number: DKPA201070539A
Authority: DK
Inventors: Peter Toft Madsen
Original assignee: Envision Energy Denmark Aps
Priority date: 2010-12-10
Filing date: 2010-12-10
Publication date: 2012-03-05
Also published as: CN203230543U; DE212011100183U1; WO2012076018A1

Abstract

An off-shore wind turbine liaving a wave nin-tip defleetor is deseribed. The deflector extends aH around the circumference of the lower end of the wind turbine tower, and acts to prevent wave run-up advancing vertically along the tower surface and dantag ing wind turbine cornponents. A number of different deflector designs are presented.

Description

DK 177158 B1 i

Field of the Invention

The present invention relates to a wave run-up deflector for an off-shore wind turbine. Background of the Invention

An example of an off-shore wind turbine 10 is shown in Fig. 1. The off-shore wind 5 turbine 10 comprises a wind turbine tower 12 and a nacelle 14 located at the top of said tower 12. The tower 12 extends above the water level 13. A hub 16 is provided at said nacelle 14, having a plurality of rotor blades 18 mounted to said hub 16. The nacelle 14 is operable to pivot such that the rotor blades 18 are oriented to face the prevailing wind direction.

10

Off-shore wind turbines 10 are generally subjected to more extreme environmental conditions than conventional on-shore turbines, e.g. typhoon- or hurricane-type conditions including large waves. Wave run-up is a phenomenon wherein waves encountering a surface above the water level, e.g. the cylindrical surface of a wind turbine 15 tower 12, will rise vertically along the surface to a maximum run-up height. In extreme wave conditions, such wave run-up may reach a height of 25 metres above normal sea level. Such potential run-up heights forces wind turbine designers to increase height clearances for wind turbines above sea level, to prevent any potential damage caused to rotor blades or to electrical systems provided at the exterior of the 20 tower surface by such large run-ups.

European Patent No. 1 240 426 describes a system wherein electrical subsystems such as switchgears or transformers are housed in containers suspended on the exterior of the wind turbine tower, a housing provided about the containers. However, 25 such a housing only provides partial protection from the elements, and does not account for the damage which may be caused by wave run-up, wherein waves may impact on the wind turbine tower 12 from any possible angle and direction.

It is an object of the invention to provide an off-shore wind turbine having adequate 30 protection from wave run-up.

2 DK 177158 B1

Summary of the Invention

Accordingly, there is provided an off-shore wind turbine wherein the wind turbine comprises a wind turbine tower and a wind turbine nacelle provided at an upper end of said tower, said nacelle comprising a hub and a plurality of rotor blades, said rotor 5 blades having a length of at least 35 metres, wherein the wind turbine further comprises a wave run-up deflector provided on said wind turbine tower, said wave run-up deflector extending around the periphery of said tower.

As the deflector extends about the entire periphery of the wind turbine tower, this 10 means that wave run-up from any direction will be adequately deflected without causing damage to wind turbine components located above the deflector. Preferably, the deflector extends an equidistant amount from the surface of the tower in all directions. This ensures that equal protection is provided from wave run-up which may impact on the tower from any direction. Preferably, the deflector is located towards 15 the base of said tower, above the water level for the wind turbine.

Preferably, said wind turbine further comprises at least one container for housing wind turbine electrical subsystems, said at least one container mounted on the exterior of said wind turbine tower, wherein said at least one container is spaced from 20 said wave run-up deflector, and wherein said wave run-up deflector is arranged to prevent wave run-up from reaching said at least one container.

The use of a deflector prevents wave run-up from reaching electrical subsystem containers, wherein the run-up could potentially damage the contained subsystem com-25 ponents. As the container is spaced from the deflector, there is greater protection from the effects of wave run-up, as any extreme wave conditions which may result in a portion of run-up passing the deflector location will not immediately reach the container location. Any such overspill of run-up beyond the deflector will likely be of reduced strength (the majority of the power of the wave run-up absorbed by the de-30 flector), and therefore extremely unlikely to cause damage to the electrical subsystem containers or any contained components.

Preferably, said at least one container is spaced at least 2 metres above said wave runup deflector.

3 DK 177158 B1

Preferably, said at least one container is mounted below the lower rotor blade tip clearance height, said wave run-up deflector located between said container and the water line for said off-shore wind turbine.

5

As the rotor hub and nacelle may pivot about on top of the wind turbine tower, the container is preferably mounted beneath the clearance height of the rotor blades.

Preferably, said deflector is arranged to re-direct wave run-up.

10

Preferably, said deflector comprises a substantially circular collar member projecting from the surface of the wind turbine tower, said collar member extending about the circumference of said wind turbine tower.

15 Preferably, the deflector comprises an angled ramp section extending from the tower surface to the outer edge of said circular collar member. Preferably, said angled ramp section is provided on the lower surface of said circular collar member.

The use of an angled ramp section acts to gently re-direct or guide the wave run-up 20 away from the surface of the tower, and reduces any wear-and-tear that might be caused on the deflector due to the explosive impact of the waves on the deflector surface.

Preferably, said deflector comprises a substantially concave lower surface.

25

The use of a concave lower surface of the deflector allows for any wave run-up to be redirected, e.g. such that the direction of the run-up is reversed. In such a case, the wave run-up can be directed back towards the water level.

30 Preferably, the deflector comprises a substantially torus-shaped structure provided about the circumference of said wind turbine tower, wherein said torus-shaped structure comprises at least one aperture provided on the lower side of said structure to collect any wave run-up within said structure.

4 DK 177158 B1 A torus-shaped deflector comprising an aperture to receive wave run-up would present a deflector having an open-hoop-shaped cross-section. Such a deflector may act to collect the entire volume of wave run-up within the structure before allowing the water to fall back to the water level under the force of gravity. This may act to pre-5 vent any run-up to splash from the surface of the wind turbine tower beyond the edges of the deflector. Such a deflector may further comprise an arrangement of drainage holes provided in the deflector to allow for the drainage of collected water.

Preferably, said deflector comprises at least one helical projection provided on the 10 surface of said wind turbine tower.

The use of a helical deflector allows for wave run-up to be re-directed to twist around the periphery of the tower, and acts to reduce the vertical height which the wave runup will reach.

15

Preferably, said deflector comprises a plurality of vertically aligned projection members provided on the surface of said wind turbine tower, said projection members having an inverse-L shape.

20 The use of a series of separate projection members which can be affixed to the external surface of a wind turbine tower allows for the relatively easy retro-fitting of such a deflector construction. The use of an inverse-L profile for the members means that the upper end of the projecting members may act to re-direct wave run-up in any particular direction. It will be understood that any suitable profile of projecting members 25 may be used, for example the upper end of the projecting members may comprise a dogleg profile or a hooped, hooked or crook-type construction.

Preferably, said projection members are provided in a spaced parallel vertical alignment forming a series of channels between adjacent members, wherein the upper ends 30 of said inverse-L-shaped projection members are directed towards an adjacent projection member to form a deflection element provided at the upper end of each of said channels.

5 DK 177158 B1

Arranging the projection members to form individual channels on the surface of the wind turbine tower allows for the power of any wave run-up to be divided between the different channels. The upper ends of each of the projection members are angled in a dogleg towards the next adjacent member around the periphery of the wind tur-5 bine tower surface. This allows the deflection of any run-up contained by the channel.

In an alternate embodiment, said projection members are provided in a closely adjacent vertical alignment, wherein the upper ends of said inverse-L-shaped projection members project away from the surface of said wind turbine tower.

10

The arrangement of the projection members such that adjacent members abut one another provides a projecting collar-type of deflector, made up of individual projecting members. The collar formed by the upper ends of these members may have any suitable cross-section, defined by the shape of the upper ends of the projecting mem-15 bers.

Preferably, said projecting members comprise a hollow structure. The projecting members may be substantially filled with impact reducing material, e.g. fluids, polymers, foam, etc.

20

The projecting members may also act as a buffer element for the lower end of the wind turbine tower. Such buffer elements may reduce the damage down to the tower structure due to high strength waves, debris collisions, collisions with sea vessels, etc.

25

Preferably, said wind turbine tower comprises a plurality of channels defined on the surface of the lower end of said tower.

The use of channels on the surface of the wind turbine tower allows for wave run-up 30 to be more effectively directed, e.g. away from the upper portions of the wind turbine structure. Such channels may act as wave run-up deflectors.

Preferably, said channels comprise a series of spaced horizontal channels formed on the surface of the wind turbine tower.

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The use of a series of circumferential channels or ditches formed along a portion of the height of the wind turbine tower provides an undulating surface which can act to disrupt the vertical rise of wave run-up along the tower surface.

5

Preferably, said channels comprise at least one helical channel extending about a portion of the lower end of the wind turbine tower. In addition or alternatively, said channels comprise a series of spaced vertical channels formed on the surface of the wind turbine tower.

10

Preferably, said channels are tapered. Preferably, said tapered channels are tapered along the channel width. Additionally or alternatively, said channels are tapered along the channel length.

15 The use of tapered channels may act to ‘push’ any wave run-up contained in the channels away from the surface of the wind turbine tower, effectively re-directing the wave run-up away from a straight vertical rise along the surface of the tower.

Preferably, said deflector is mounted to the surface of the wind turbine tower. Alter-20 natively, said deflector may be integrally formed with the surface of the wind turbine tower.

Preferably, said deflector is located at least 15 metres above the water line of said offshore wind turbine tower.

25

The positioning of the deflector a distance above the water line means that the deflector is used to prevent against damage caused by extreme wave conditions. Such a positioning means that the maintenance for such a deflector is reduced, due to the relatively rare occasions that the deflector will be impacted by wave run-up.

30

Preferably, said wind turbine tower is approximately 80 metres tall above the water line for said tower, the rotor blades having a radius of approximately 60 metres. A deflector positioned 15 metres above the water line for said tower results in approxi- 7 DK 177158 B1 mately 5 metres distance between the deflector and the lower clearance height of the rotor blades.

Preferably, the deflector is formed as a sleeve element which may be fitted around a 5 section of the wind turbine tower during tower construction or manufacture.

Description of the Invention

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 10 Fig. 1 is an illustration of a known off-shore wind turbine; and

Fig. 2(a)-(e) are enlarged views of embodiments of a wave run-up deflector according to the invention, as installed on a wind turbine tower.

It is proposed to reduce the damage caused by wave run-up through the use of a suit-15 able wave run-up deflector, provided at the lower end of a wind turbine tower 12.

With reference to Fig. 2(a)-(e), a number of different embodiments of a wave run-up deflector are indicated at 20a-20e respectively (for ease of illustration, only a section of the wind turbine tower 12 is shown). The deflectors 20a-20e are located towards the lower end of the wind turbine tower 12, above the water line for that tower.

20

Fig. 2(a) illustrates a first embodiment of wave deflector 20a. The deflector 20a comprises a circular collar which extends around the circumference of the wind turbine tower 12. The circular collar of the deflector 20a projects from the surface of the tower 12, such that any wave run-up rising vertically along the tower 12 hits the col-25 lar and is prevented from travelling higher along the tower 12.

As can be seen in Fig. 2(a), the lower surface of the deflector 20a comprises an angled ramp 22 which extends from close to the surface of the tower 12 to the outer edge of the circular collar of the deflector 20a. The use of the ramp 22 causes the 30 relatively high power of the wave run-up to be re-directed away from the tower 12, and not absorbed by the deflector 20a itself, as the ramp 22 guides any wave run-up away from the surface of the tower 12. It will be understood that the deflector 20a may be used either with or without the ramped section 22.

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Fig. 2(b) shows a second embodiment of wave deflector 20b. The deflector 20b comprises a circular ring element extending around the surface of the tower 12. The lower surface of the deflector 20b is curved to form a concave lower surface 24, such that 5 the concave surface faces towards the water level. Such a concave lower surface 24 acts to ‘turn around’ any wave run-up, so that the direction of the run-up is reversed back towards the sea level. Again, such a construction does not seek to absorb the full strength of the wave run-up, rather to re-direct it away from sensitive sections of the wind turbine.

10 A further version of this design may include wherein the lower surface of the deflector 20b is curved through a further 90° or so, such that the deflector 20b substantially forms a torus ring around the wind turbine tower 12. Preferably, the torus would comprise an aperture or a channel, preferably adjacent the tower surface, so that wave 15 run-up along the tower 12 would flow into the interior of the torus, and prevented from splashing or deflecting beyond the deflector in any way (being contained within the substantially enclosed structure of the torus). The torus structure may comprise drainage holes of channels to allow for the subsequent draining of the captured runup.

20

Fig. 2(c) illustrates a third embodiment of wave deflector 20c. The deflector 20c comprises a projecting member provided on the surface of the tower 12, the member arranged to twist in a helical manner about the tower surface. The deflector 20c of Fig 2(c) shows a single projecting member which performs two complete revolutions 25 of the circumference of the tower 12, but it will be understood that any number of parallel projecting members may be used, having any suitable twist angle and any number of revolutions of the tower 12 circumference.

The use of a helical twist acts to re-direct any wave run-up to twist about the surface 30 of the tower 12, thereby reducing the vertical height to which the wave run-up will reach.

Fig. 2(d) shows a fourth embodiment of wave deflector 20d. The deflector 20d comprises a series of vertically-aligned parallel spaced projecting rails or members ar- 9 DK 177158 B1 ranged about the circumference of the lower section of the tower 12. The upper ends 26 of the projecting members are angled in a dogleg-type arrangement, forming an inverted-L shape of member. The angled ends of the members are aligned in the same direction on the surface of the tower, facing towards the upper end 26 of the adjacent 5 projecting member. This design forms a number of channels between adjacent projecting members, such that the full strength of the wave run-up may be divided between different adjacent channels. The angled upper ends 26 provided at the upper ends of the channels deflect the contained wave run-up.

10 Fig. 2(e) shows a fifth embodiment of wave deflector 20e. The deflector 20e comprises a series of vertically-aligned abutting projecting bars or members. As with the embodiment of Fig. 2(d), the projecting members of the deflector 20e comprise an angled upper end 28. However, in this embodiment, the members are not spaced apart, and the upper ends 28 face away from the surface of the tower 12. In this case, 15 the deflector 20e functions in a similar manner to the deflector 20a of the first embodiment, wherein any wave run-up is guided away from the surface of the tower 12.

It will be understood that the upper ends 28 of said projecting members may comprise any suitable profile, for example the upper end of the projecting members may comprise a dogleg profile or a hooped, hooked or crook-type construction.

20

It will be understood that other designs of deflector are foreseen. For example, the deflector may comprise a series of channels defined on the surface of the lower end of the tower 12. Such channels may be provided at any angle to the central longitudinal axis of the wind turbine tower 12, e.g. horizontal channels, vertical channels, helical 25 channels. The use of spaced horizontal channels would provide an undulating tower surface, which would act to absorb some of the energy of the wave run-up, and thereby disrupt the vertical rise of the wave run-up along the tower surface. Such channels may be length-wise and/or width-wise tapered. The use of tapered channels may act to ‘push’ any wave run-up contained in the channels away from the surface 30 of the wind turbine tower, effectively re-directing the wave run-up away from a straight vertical rise along the surface of the tower.

It will be understood that the deflectors 20a-e may be formed as substantially hollow elements, and may act as a buffer or bumper element for the lower level of the wind 10 DK 177158 B1 turbine tower 12, to reduce damage which may be caused by sea vessel, marine debris, etc. colliding with the wind turbine tower 12 structure. In such a case, the deflectors 20a-e may be substantially filled with an impact-absorbing material, e.g. a flexible polymer, a fluid, etc.

5

While the deflector may be formed integrally with the surface of the wind turbine tower 12, it will be understood that the deflector may be retrofitted to an existing wind turbine tower 12 structure, or may be mounted to a section of a wind turbine tower 12 during manufacture. The deflector may be provided as a sleeve element 10 which can be fitted around a section of the tower 12, or may be comprised of a series of elements which can be attached to the tower surface to form the complete deflector (e.g. 20d,20e).

Preferably, the deflector will be used with a wind turbine 10 comprising at least one 15 container mounted to the exterior of the wind turbine tower 12 structure. Such a container may be used for the housing of wind turbine electrical subsystems and control modules, e.g. switchgears, transformers, etc. The use of external subsystem containers allows for relatively easy servicing and replacement of sensitive components. The use of a wave run-up deflector will reduce the damage caused to any external subsys-20 tern containers or the contained components due to wave run-up.

Preferably, the container is spaced from the location of the deflector, to ensure that any wave run-up related damage is effectively eliminated, as any extreme wave conditions which may result in a portion of run-up passing the deflector location will be 25 distant from the location of the container. As such overspill is likely to be considerably weakened in wave power by the deflector, it is unlikely that such overspill will reach the container, and any such spill which may reach the container will most likely not have strength sufficient to damage either the container or the contained components.

30

11 DK 177158 B1

In preferred embodiments, the wave run-up deflector is located at least 15 metres above the water line of the off-shore wind turbine tower 12. This means that the deflector will only be needed in extreme wave conditions, i.e. wherein wave run-up is greater than 15 metres. This limiting of the deflector to the impact of lesser wave run-5 up will mean that the maintenance requirements for such a deflector will be reduced.

In a preferred embodiment, the wind turbine tower 12 is approximately 80 metres high above the water line, the turbine rotor blades 18 having a radius of approximately 60 metres. A deflector positioned 15 metres above the water line for said 10 tower results in approximately 5 metres distance between the deflector and the lower clearance height of the rotor blades.

It will be understood that any one of the above described deflector designs may be used either alone or in combination with any of the other suggested constructions or 15 other run-up deflector designs.

The invention is not limited to the embodiments described herein, and may be modified or adapted without departing from the scope of the present invention.

Claims

12 DK 177158 B112 DK 177158 B1

1. Offshore vindturbine hvori vindturbinen omfatter et vindturbinetåm og en vindtur-binenacelle, som er tilvejebragt ved en øvre ende af tårnet, hvilken nacelle omfatter et 5 nav og flere rotorblade, der har en længde på mindst 35 meter, hvori vindturbinen omfatter en bølgeopløbsdeflektor, som er tilvejebragt på vindturbinetåmet, hvilke bølgeopløbsdeflektor strækker sig omkring tårnets periferi.An offshore wind turbine wherein the wind turbine comprises a wind turbine bar and a wind turbine cell provided at an upper end of the tower, said nacelle comprising a 5 hub and multiple rotor blades having a length of at least 35 meters, wherein said wind turbine comprises a wave-flow deflector, which are provided on the wind turbine bar which wave deflector extends around the periphery of the tower.

2. Offshore vindturbine ifølge krav 1, hvori vindturbinen yderligere omfatter mindst 10 en beholder til at huse elektriske delsystemer for vindturbinen, hvor den mindst ene beholder er monteret på vindturbinetåmets ydre, hvori den mindst ene beholder er anbragt i afstand fra bølgeopløbsdeflektoren, og hvori bølgeopløbsdeflektoren er indrettet til at hindre bølgeløb i at nå den mindst ene beholder.An offshore wind turbine according to claim 1, wherein the wind turbine further comprises at least 10 a container for housing electrical wind turbine subsystems, wherein the at least one container is mounted on the exterior of the wind turbine bar, wherein the at least one container is spaced from the wave flow deflector and wherein the wave flow deflector is designed to prevent waveguides from reaching the at least one container.

3. Offshore vindturbine ifølge krav 2, hvori den mindst ene beholder er anbragt mindst 2 meter over bølgeopløbsdeflektoren.An offshore wind turbine according to claim 2, wherein the at least one container is located at least 2 meters above the wave flow deflector.

4. Offshore vindturbine ifølge ethvert af de foregående krav, hvori deflektoren omfatter et i det væsentlige cirkulært kraveelement, der rager ud fra vindturbinetåmets 20 overflade, hvilket kraveelement strækker sig om vindturbinetåmets omkreds.An offshore wind turbine according to any of the preceding claims, wherein the deflector comprises a substantially circular collar member projecting from the surface of the wind turbine bar 20, which collar extends around the circumference of the wind turbine bar.

5. Offshore vindturbine ifølge krav 4, hvori deflektoren omfatter en vinklet rampeafsnit, der strækker sig fra tårnets overflade til det cirkulære kraveelements ydre kant.An offshore wind turbine according to claim 4, wherein the deflector comprises an angled ramp section extending from the surface of the tower to the outer edge of the circular collar element.

6. Offshore vindturbine ifølge krav 4, hvori deflektoren omfatter en i det væsentlige konkav nedre overflade.An offshore wind turbine according to claim 4, wherein the deflector comprises a substantially concave lower surface.

7. Offshore vindturbine ifølge ethvert af de foregående krav, hvori deflektoren omfatter mindst et spiralformet fremspring, som er tilvejebragt på overfladen af vindturbi-30 netåmet. 13 DK 177158 B1An offshore wind turbine according to any one of the preceding claims, wherein the deflector comprises at least one helical projection provided on the surface of the wind turbine mesh. 13 DK 177158 B1

8. Offshore vindturbine ifølge ethvert af de foregående krav, hvori deflektoren omfatter flere lodretstillede fremspringende elementer, som er tilvejebragt på overfladen af vindturbinetåmet, hvilke fremspringende elementer har omvendt L-form.An offshore wind turbine according to any one of the preceding claims, wherein the deflector comprises a plurality of vertical projecting elements provided on the surface of the wind turbine bar, which projecting elements have an inverted L-shape.

9. Offshore vindturbine ifølge krav 8, hvori de fremspringende elementer er tilveje bragt lodret og parallelt med indbyrdes afstand, så de danner en række kanaler mellem tilstødende elementer, hvori de øvre ender af de omvendt L-formede fremspringende elementer er rettet mod et tilstødende fremspringende element for at danne et afbøjende element ved den øvre ende af hver af kanalerne. 10An offshore wind turbine according to claim 8, wherein the protruding elements are arranged vertically and parallel to each other to form a series of channels between adjacent elements, wherein the upper ends of the inverted L-shaped protuberances are directed to an adjacent protrusion. element to form a deflecting element at the upper end of each of the channels. 10

10. Offshore vindturbine ifølge krav 8, hvori de fremspringende elementer er tilvejebragt stillet tæt sammen lodret langs med hinanden, hvori de øvre ender af de omvendt L-formede fremspringende elementer rager væk fra overfladen af vindturbinetåmet. DK 177158 B1 14 16. i Wfi 10^^^ 1—: 1 18^^ ^^ j: j. 12 J j ^ ^ Fig. 1 |——-_____12 DK 177158 B1 20a ^-20b __--22 V V 24 (a) (b) --12 —20c (c) ____12 ____12 if rir26 : ^ 20d · ' ''20e (d) (e) Fig. 2An offshore wind turbine according to claim 8, wherein the projecting elements are arranged close together vertically along one another, the upper ends of the inverted L-shaped projecting elements projecting away from the surface of the wind turbine barrel. DK 177158 B1 14 16. i Wfi 10 ^^^ 1—: 1 18 ^^ ^^ j: j. FIG. 1 | ——-_____ 12 DK 177158 B1 20a ^ -20b __-- 22 VV 24 (a) (b) --12 -20c (c) ____12 ____12 if rir26: ^ 20d · '' '20e (d) (e) FIG. 2