EP4121654A1

EP4121654A1 - Method of installing parts of an offshore wind turbine generator

Info

Publication number: EP4121654A1
Application number: EP21712960.0A
Authority: EP
Inventors: Sedin BUZDALEK; Mads Møller KRISTENSEN; Torben Damsgaard
Original assignee: Vestas Wind Systems AS
Current assignee: Vestas Wind Systems AS
Priority date: 2020-03-20
Filing date: 2021-03-10
Publication date: 2023-01-25
Also published as: WO2021185421A1

Abstract

The invention relates to a method of installing parts of an offshore wind turbine generator, and in particular parts such as an nacelle or one or more blades of the wind turbine generator. This in order e.g. to an even more hassle free, safer and faster installation during most offshore conditions. There is disclosed a method of installing a part of an offshore wind turbine generator, where the wind turbine generator is to be installed on a foundation (102). The method includes providing (301) an air bubble zone (304) in the water in a vicinity of at least part the foundation, installing (401) the wind turbine generator part (404) to the foundation or to a previously installed wind turbine generator part, while air bubbles (302) are present in the air bubble zone.

Description

METHOD OF INSTALLING PARTS OF AN OFFSHORE WIND TURBINE GENERATOR

FIELD OF THE INVENTION The invention relates to a method of installing parts of an offshore wind turbine generator, and in particular parts such as a nacelle or one or more blades of the wind turbine generator.

BACKGROUND OF THE INVENTION

A horizontal axis offshore wind turbine typically comprises a tower supporting a nacelle to which a rotor is mounted. The rotor comprises one or more wind turbine blades which extend radially from a central hub. Installation of the blades should be possible under various conditions, and at least the most common, offshore conditions. However, especially when parts of an offshore wind turbine generator must be mounted to a previously installed part, such as when installing a wind turbine blade to the central hub of the rotor, difficulties may arise. Various solutions exist for mitigating and/or preventing such difficulties, such as using installation cranes with complicated heave compensation systems, and/or such as systems for making it easier to mate the parts by providing additional mating means on one or both of the parts.

However, due to varying offshore environmental conditions, a need for making installation e.g. even more hassle free, safe and faster during most conditions continues to exist.

Thus, in order to solve such or other issues, disadvantages or problems with existing methods and systems for use when installing parts of an offshore wind turbine, it has been appreciated that an improved method of installing a part of an offshore wind turbine generator is of benefit, and in consequence, the present invention has been devised. SUMMARY OF THE INVENTION

It may be seen as an object of the present invention to provide an improved method of installing a part of an offshore wind turbine generator. Preferably, the invention alleviates, mitigates or eliminates one or more of the above or other disadvantages singly or in any combination.

It may alternatively or additionally be seen as an object of the present invention to provide an improved wind power plant. In particular, it may be seen as an object to provide a solution which decreases one or more or all of a cost of designing the wind power plant, a cost of the materials and equipment used in the wind power plant, a cost of commissioning the wind power plant, a cost of maintaining the wind power plant - while maintaining or increasing a life time of the wind power plant and maintaining or increasing a power production of the wind power plant.

In particular, it may be seen as an object of the invention to provide a method of installing a part of an offshore wind turbine generator which is even more hassle free, safe and faster during most offshore conditions.

Accordingly there is provided a method of installing a part of an offshore wind turbine generator, where the wind turbine generator is to be installed on a foundation provided in water, the method comprising

- providing an air bubble zone in the water in a vicinity of at least part the foundation, and wherein the method further comprises

- installing the wind turbine generator part to the foundation or to a previously installed wind turbine generator part, while the air bubbles are present, and where the air bubbles are provided by releasing air at one or more depths and at one or more positions under a water level.

Thus, an improved method of installing a part of an offshore wind turbine generator is provided. The improvement may be seen to be present when installing the part of the wind turbine generator as submitted herein and given the insight provided herein. In particular, it may be seen as an advantage of the present invention that due to providing the air bubble zone as claimed and disclosed herein, the wind turbine generator part can be installed with e.g. one or more of less hassle, more safe and/or faster than with existing solutions.

An alternative solution is thus described for solving a cause of some of the problematics which arises during offshore installation. This does not mean that all of the existing solutions should not be used along with the present disclosed technology, but moreover that the disclosed solution may also be seen as an addition to use when using existing solutions.

The air bubble zone has an increased amount of air bubbles compared to water present away from the zone when the bubbles are provided. The increase is significant, such as that it includes at least 5 percent more air, moreover at least 10 percent more air, and in particular at least 20 percent more air.

Depending on conditions of the water, e.g. current, waves etc, and a wanted decrease in a force which the water should exert on the foundation, the needed amount of bubbles can be determined. Possibly, the amount will just be increased from a given level and adjusted until any movements of the foundation or e.g. a tower fixed to the foundation has settled below a predetermined threshold.

Such adjustment or setting can include a control loop, e.g. receiving feedback from one or more acceleration sensors positioned on the foundation and/or measuring acceleration and/or position of any wind turbine generator parts already installed and/or in dependence of feedback from measurements of movements of the foundation or wind turbine generator parts already installed using distance measurements or similar and/or in dependence of preliminary or continued measurements of a speed of water current, direction of the water current and/or wave height at one or more positions at the foundation etc.

In dependence of various factors as discussed, a load on the foundation may e.g. be estimated to be reduced by the bubbles by 50%, e.g. when filling the air bubble zone in the vicinity of the foundation with a 50/50 ratio of air and water, and thus decrease density of the mix accordingly. In any event, the air bubble zone is provided as an air bubble barrier between the foundation and water present away from the zone. Evidently, when the air is released at some level under water, bubbles will form, which bubbles are released in open air at the water level.

According to embodiments of the invention, the air bubble zone is surrounding or substantially surrounding the foundation. Hereby, e.g., a push and drag phenomena, or variating push and drag forces, around the foundation may be mitigated in the best manner and/or a varying factor of shifting current directions may be mitigated.

According to embodiments of the invention, the air bubble zone is provided from at least 5 meter below a sea level, such as from at least 7, 10, 15 or 20 meter below the water level. It has been found that the most impact and/or the easiest control of a movement of the bubbles can be provided when, at least to some extent, limiting the zone vertically to the top most part of the water and/or by releasing air at various depths and/or positions. This may also require less air for a given wanted decrease in a force which the water surrounding the foundation has on the movement of the foundation.

Under particular conditions, it has been found that it may be preferred that the air bubbles circumference the entire foundation. Under those or other conditions, it may alternatively or additionally be preferred that an upper third of a foundation, such as a monopile foundation, but possibly at least 10 - 15 m of water column is provided with an air bubble zone.

It is to be understood, that it may not necessarily be the purpose to attempt to fully replace the water around the foundation with air or to provide a very high concentration of air in the zone, but moreover to at least partly mitigate the variating force that current and waves exerts on the foundation. Thus sideways variance in force exerted on the foundation by the water, sea or ocean is unwanted.

Further, it is an insight disclosed hereby, that providing even a minor, but adjusted amount of air bubbles in the zone around e.g. a monopile foundation, naturally moving substantially vertically upwards, i.e. providing an upwards flow, may decrease the variance of a horizontal force exerted on the foundation, and thus shield or stabilize the foundation with regard to horizontal forces.

This while the water still has a weight and load 'supporting' and stabilizing the foundation horizontally (sideways). Thus, in other words, it may be regarded that the technology includes to saturate at least part of the water, or at least part of a water column around a foundation such as a monopile with bubbles to reduce the density of the water. By doing that, an influence of a hydrostatic pressure difference (front side/rear side, and/or variance) is reduced over the foundation, e.g. by reducing a density of the current and/or a waves density and/or a wave height.

In accordance with embodiments of the invention, the air bubble zone is provided from a seabed level, or from a level just above the seabed level, such as from 5 meters above the seabed level. For some conditions of e.g. of the seabed, it may be appreciated not to release the air at the seabed to prevent any erosion of the seabed at the foundation.

When the air bubble zone in the vicinity of the at least part the foundation has a width of at least 0.5 meter, such as at least 1, 2, 3, 4 or 5 meters, and where the width is found by testing to be particularly suited under various conditions, suited widths of the zone are disclosed. The width may be measured and present at one or more depths, such at sea level or at 3-5 meter water depth. Still further, if or when releasing air at different depths and positions, certain different widths may be present at different depths.

This may also be used to tune an effect of the solution, e.g. by releasing different amounts of air at different places and/or depths, e.g. in different ways. Thus, in accordance with further embodiments of the invention the air bubbles are provided by releasing air at a plurality of depths and at a plurality of positions under a water level. Release may follow by ways of simply letting the air out by various means such as diffusers, and/or air mats with numerous holes spreading air more gently over a larger area etc. In particular it may e.g. be chosen to release the air in one distance from the foundation at one depth, whereas it may be preferred to release the air at another distance from the foundation at a second depth.

In particular, and as an example, it may be advantageous to reduce drag behind the foundation (when seen from a current and/or direction of waves perspective) by bubbles distributed to a larger extend vertically in the vicinity of the foundation, whereas in front of the foundation it may be beneficial to focus more on a certain horizontal distribution to yield the best effect.

As an alternative or an addition to controlling the bubbles by release depth, position or manner, one or more guides, such as vertically or substantially vertically extending guides, may be provided in the water so as at least partly to control movement of the bubbles. This may be provided by one or more finely masked nets or similar, possibly held at a distance from the foundation by suitable distancing means.

When at least 10, such as at least 25, 50, 100 or 500 or more cubic metres of air are released per minute under the water level to provide the air bubbles in the zone, at one or more position and/or one or more depths and by one or more different means and/or distances from the foundation, or from a centre of a foundation - amounts of air to be used under various conditions are disclosed. The amounts may be adjusted during use, and even between different positions e.g. using a control loop as described herein.

The technology may be useable for a floating foundation or a seabed foundation, which seabed foundation is supported on or in a seabed, such as a monopile foundation or a jacket foundation. A sea vessel, barge, or jacked up sea vessel or jacked up barge may be used to provide the air and equipment needed for carrying out the method. The sea vessel may include one or more of an air pressurizing means, an air tank, a system of hoses or tubes or similar, a net including a system of hoses, tubes or similar and where the net and/or the hoses, tubes or similar are adapted to be coupled to one or more of the air pressurizing means and the air tank, so as, when in use, for at least part of the net and/or the hoses, tubes or similar to be lowered into the water for providing air bubbles according to the herein disclosed. By referring to an advantage herein, it must be understood that this advantage may be seen as a possible advantage provided by the invention, but it may also be understood that the invention is particularly, but not exclusively, advantageous for obtaining the described advantage.

In general, the various aspects and advantages of the invention may be combined and coupled in any way possible within the scope of the invention.

These and other aspects, features and/or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

FIG. 1 is a simplified illustration showing a sideview of a foundation for an offshore wind turbine generator, which has not yet been fully installed,

FIG. 2 is the sideview of figure 1, but where a sea vessel is present close to the foundation,

FIG. 3 illustrates that air bubbles are provided in the vicinity of the foundation, FIG. 4 illustrates installing a wind turbine generator part to a previously installed wind turbine generator part, while air bubbles are present,

FIG. 5 is a top-view of the foundation at about just below sea level illustrating a width of an air bubble zone surrounding the foundation,

FIG. 6 illustrates guides provided in the water so as to at least partly control movement of the air bubbles, and

FIG. 7 shows air bubbles provided by releasing air at two depths. DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a sideview of a foundation 102 of an offshore wind turbine generator under installation, i.e. which has not yet been fully installed. It is illustrated that the generator at that moment of time includes a tower 110 and a nacelle 112. The foundation is provided in water with a water level 104 over a seabed 108.

A so-called monopile foundation supported in the seabed is illustrated, but the foundation may alternatively be a jacket foundation such as a three- or four- jacket foundation. Still further, the foundation may be of a floating type, but in that case, the present technology is possibly most feasible to reduce (variance in) drag of the floating foundation.

Whereas the illustrations is of a situation where a blade of the wind turbine generator is to be installed, the technology may be applied during installation of other parts, such as the tower to the foundation and/or the nacelle to the tower. Still further, the method may be applied, e.g. in case one or more blades needs to be replaced or taken off and remounted for maintenance or similar. It may even be that a solution as the disclosed herein, or similar to it, may be used when the turbine has been fully commissioned.

However, and even though permanent or preinstalled outlets or tubing or similar may be used, the solution may be preferred as a temporary solution to be used when there is difficulties or foreseen difficulties, e.g. with blade installation. The solution may be seen as a passive way of damping foundation movements, by mitigating or reducing a cause of such movements. Since preferably applied only in limited periods, the air bubbles are not foreseen to provide unwanted corrosion etc. The solution may be seen as a safe way of reducing foundation movements, and thus movements of any wind turbine generator parts installed on the foundation. Possible, a (crane) vessel provider already present at site, e.g. for the installation or similar, may have the means to carry out the method onboard.

FIG. 2 is the sideview of figure 1, but where a sea vessel 204 is present close to the foundation. The sea vessel, here shown as jacked up, but it may be a vessel not able to do so. The vessel includes one or more of an air pressurizing means, an air tank 202, a system 206 of hoses or tubes or similar, a net including a system of hoses, tubes or similar and where the net and/or the hoses, tubes or similar are adapted to be coupled to one or more of the air pressurizing means and the air tank 202, so as, when in use, for at least part of the net and/or the hoses, tubes or similar to be lowered into the water for providing air bubbles 302 as submitted herein.

FIG. 3 illustrates that air bubbles are provided in the vicinity of the foundation, and as illustrated with dots, the air bubble zone 304 has a significantly increased amount of air bubbles compared to water present away from the air bubble zone. Thus, the air bubble zone is provided as a sort of barrier between the foundation 102 and water present away from the zone.

FIG. 4 illustrates installing a wind turbine generator part to a previously installed wind turbine generator part, while air bubbles are present, where the wind turbine generator is to be installed on a foundation 102 provided in water. The method includes providing 301 an air bubble zone 304 in the water in a vicinity of at least part the foundation, and installing 401 the wind turbine generator part 404 to the foundation or to a previously installed wind turbine generator part (here a blade 404 to the hub 402 of the nacelle, i.e. a wind turbine generator blade part to a previously installed wind turbine generator hub of the nacelle), while air bubbles 302 are present. The air bubbles are provided by releasing air at one or more depths 702, 704 and at one or more positions 706, 708 under a water level 104, and letting the air form bubbles to be released in open air at the water level.

Another vessel (not shown) having the wind turbine generator parts and likely a crane for use when installing the wind turbine generator parts, may also be present at the foundation. Alternatively, such vessel may include the means, such as compressor means, air tank, tubes etc for carrying out the method disclosed herein.

FIG. 5 is a top-view of the foundation at about just below sea level, and illustrating a width of an air bubble zone surrounding the foundation. The air bubble zone 304 in the vicinity of the at least part the foundation may have a width 502, such as of at least 0.5m, such as at least 1, 2, 3, 4 or 5 meters. It follows from the figure that the air bubble zone is surrounding the foundation.

FIG. 6 illustrates guides 602 provided in the water so as to at least partly control movement of the air bubbles. In the illustration the guides are provided substantially vertically in the water at a wanted outer barrier of the zone, and thus provided in the water so as to at least partly control movement, particularly horizontal movement, of the air bubbles.

FIG. 7 shows air bubbles provided by releasing air at two depths 702 and 704, and thus at a plurality of positions 706 and 708 under the water level. Several outlets may be present and are foreseen at one or more depths. In particular, outlets all around a monopile have been found of benefit, especially for situations with varying wind and/or wave directions. E.g. in other conditions, or for particular purposes, it has been found more or equally beneficial to only have several outlets on one side, and then e.g. let the current move the air bubbles all around the foundation, such as a monopile.

In short, it is herein disclosed that the invention relates to a method of installing parts of an offshore wind turbine generator, and in particular parts such as an nacelle or one or more blades of the wind turbine generator. This in order e.g. to an even more hassle free, safer and faster installation during most offshore conditions. There is disclosed a method of installing a part of an offshore wind turbine generator, where the wind turbine generator is to be installed on a foundation 102. The method includes providing 301 an air bubble zone 304 in the water in a vicinity of at least part the foundation, installing 401 the wind turbine generator part 404 to the foundation or to a previously installed wind turbine generator part, while air bubbles 302 are present in the air bubble zone.

Although the present invention has been described in connection with preferred embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. In this section, certain specific details of the disclosed embodiment are set forth for purposes of explanation rather than limitation, so as to provide a clear and thorough understanding of the present invention. However, it should be understood readily by those skilled in this art, that the present invention may be practised in other embodiments which do not conform exactly to the details set forth herein, without departing significantly from the spirit and scope of this disclosure. Further, in this context, and for the purposes of brevity and clarity, detailed descriptions of well-known apparatus, circuits and methodology have been omitted so as to avoid unnecessary detail and possible confusion.

In the claims, the term "comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second" etc. do not preclude a plurality. Reference signs are included in the claims however the inclusion of the reference signs is only for clarity reasons and should not be construed as limiting the scope of the claims.

Claims

1. A method of installing a part of an offshore wind turbine generator, where the wind turbine generator is to be installed on a foundation (102) provided in water, the method comprising

- providing (301) an air bubble zone (304) in the water in a vicinity of at least part the foundation, and wherein the method further comprises

- installing (401) the wind turbine generator part (404) to the foundation or to a previously installed wind turbine generator part, while air bubbles (302) are present, and where the air bubbles are provided by releasing air at one or more depths (702, 704) and at one or more positions (706, 708) under a water level (104).

2. The method according to claim 1, wherein the air bubble zone (304) has an increased amount of air bubbles compared to water present away from the air bubble zone (304) when the bubbles are provided.

3. The method according to claim 1 or 2, wherein the air bubble zone is provided as a barrier between the foundation (102) and water present away from the zone.

4. The method according to any of the proceeding claims, wherein the air bubble zone is surrounding or substantially surrounding the foundation.

5. The method according to any of the proceeding claims, wherein the air bubble zone is provided from at least 5 meter below a sea level, such as from at least 7, 10, 15 or 20 meter below the water level (104).

6. The method according to any of the proceeding claims, wherein the air bubble zone is provided from a seabed level (106), or from a level just above the seabed level, such as from 5 meters above the seabed level.

7. The method according to any of the proceeding claims, wherein the air bubble zone in the vicinity of the at least part the foundation has a width (502) of at least 0.5m, such as at least 1, 2, 3, 4 or 5 meters.

8. The method according to any of the proceeding claims, wherein the air bubbles are provided by releasing air at a plurality of depths (702, 704) and at a plurality of positions (706, 708) under the water level (104).

9. The method according to any of the preceding claims, where one or more guides (602) are provided in the water so as to at least partly control movement of the air bubbles.

10. The method according to claim 9, where the one or more guides (602) comprises one or more nets or similar.

11. The method according to any of the preceding claims wherein at least 10, such as at least 25, 50, 100 or 500 cubic metres of air are released per minute under the water level to provide the air bubbles (302) in the air bubble zone (304).

12. The method according to any of the preceding claims, wherein the foundation (102) is a floating foundation or a seabed foundation, which seabed foundation is supported on or in a seabed (108).

13. A sea vessel (204) equipped with one or more means for carrying out a method according to any of the preceding claims.

14. The sea vessel according to claim 13, comprising one or more of an air pressurizing means, an air tank (202), a system (206) of hoses or tubes or similar, a net including a system of hoses, tubes or similar and where the net and/or the hoses, tubes or similar are adapted to be coupled to one or more of the air pressurizing means and the air tank (202), so as, when in use, for at least part of the net and/or the hoses, tubes or similar to be lowered into the water for providing air bubbles (302) according to any of claims 1-12.

15. Use of a sea vessel (204) according to any of claims 13 or 14, in accordance with a method in any of claims 1-12.