Floating wind power platforms and related floating wind power assemblies

Abstract

To provide a floating wind power platform that ensures sufficient isolation between the first natural period of the tower and the 1P and 3P frequencies, respectively, to provide sufficient resistance and integrity throughout the useful life of the turbine. [Solution] The present invention relates to a floating wind power generation platform, which can be installed on a body of water, and which comprises a floating structure (28) capable of floating on the body of water, and a tower (30) protruding from the floating structure (28) and extending along a main direction (Z), the tower (30) capable of supporting a wind turbine nacelle, and the tower (30) comprising a composite material.

Description

[Technical field]

[0001] The present invention relates to a floating wind power platform.

[0002] The invention also relates to an assembly comprising such a floating wind power platform. [Background technology]

[0003] Floating wind power platforms conventionally comprise a turbine, which is positioned at the end of a tower, which itself is connected at its other end to a floating structure that may float, for example in the sea. The towers are usually made of steel to provide sufficient resistance.

[0004] The turbine includes a propeller that can be rotated by the wind to power an electrical generator. The rotation of the propeller creates periodic vibrations, especially due to the propeller blades passing in front of the tower. If the frequencies of these vibrations get too close to the structural natural frequencies of the assembly, they can trigger and maintain resonances, accelerating the degradation of the assembly.

[0005] When designing a floating wind power platform, it is therefore essential to adjust the design of the floating body and tower structures to reduce tower resonance phenomena while maintaining sufficient strength performance to withstand the extreme tower bending moments induced by hull accelerations and turbine thrust.

[0006] Towers are typically designed to have a first natural mode between the so-called 1P frequency (corresponding to one revolution of the rotor) and the so-called 3P frequency (corresponding to each blade passing the tower). The design process typically requires at least 10% between the tower's first natural period and the 3P frequency to mitigate resonance phenomena.

[0007] However, compared to onshore wind turbines, when a wind turbine is installed on water, the natural period of the tower becomes longer and approaches the 3P vibration frequency, which causes resonance phenomena and results in significant fatigue damage to the tower.

[0008] Furthermore, as industrial turbines grow in size, for example to provide more than 14 MW of power, their rotational speeds are reduced to limit the relative wind speed at the blade tips to reduce erosion and avoid supersonic flows. Such a reduction in rotational speed reduces the 3P frequency, making assembly design and compliance with the 10% criterion more challenging and limiting the possibilities for optimizing the assembly design.

[0009] In order to lower the natural frequency of the tower, consideration has been given to reducing the tower stiffness. However, there is some limit to reducing the rigidity of the tower by adjusting the diameter or thickness of the tower due to the strength performance required under extreme conditions.

[0010] French Patent Application No. 3098555 proposes using an elastomer pad damping system between the tower and the hull. However, such systems are very complex and expensive to implement. In particular, the proposed connections would involve the use of large steel castings which are known to be expensive. To date, such a system has never been implemented in an actual offshore wind turbine field due to these limitations. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] French Patent Application Publication No. 3098555 Summary of the Invention [Problem to be solved by the invention]

[0012] One of the objects of the present invention is therefore to provide a floating wind power platform that ensures sufficient isolation between the first natural period of the tower and the 1P and 3P frequencies, respectively, whilst providing sufficient resistance and integrity over the entire useful life of the turbine and being cost-effective. [Means for solving the problem]

[0013] To this end, the present invention relates to a floating wind power platform that can be installed in a body of water, the platform comprising a floating structure capable of floating on the body of water and a tower protruding from the floating structure and extending along a main direction, the tower capable of supporting a wind turbine nacelle, the tower comprising a composite material. Effect of the Invention

[0014] In fact, these features can be used to reduce the natural period of the tower to an acceptable value by having the tower comprise composite materials instead of only steel. In fact, composite materials can be six times stiffer than steel for comparable strength performance. In particular, by adjusting the location and amount of composite material in the tower, the natural period of the tower can be reduced depending on the overall design of the platform and external conditions that may affect the natural period. Moreover, the composite tower is easy to manufacture and simplifies the connection to the floating structure. The present invention therefore provides a cost-effective solution to the resonance problem.

[0015] The platform according to the invention has one or more of the following characteristics, chosen alone or according to any technically feasible combination: - the tower has an inner layer made of steel and an outer layer made of composite material; - the tower has a lower part for connecting to the floating structure, an upper part capable of supporting a wind turbine nacelle, and an intermediate part arranged along a main direction between the lower part and the upper part, the intermediate part being formed of a composite material; - the lower and upper parts are made of steel; the composite material is a fiber-reinforced polyester or epoxy resin, in particular glass fibers, carbon nanotubes or carbon fibers, optionally in the form of woven or non-woven fabrics or bulk fibers; - Composites can be coated with paint to prevent degradation from environments such as UV radiation and / or salt water; - the floating structure comprises a floating body and a transition section protruding from the floating body, and the tower is fixed to the transition section; - The tower is fixed to the transition section via a bolted flange, - The tower is grouted in transition; - the transition section extends along the main direction for a length comprised between 40 cm and 20 m;

[0016] The invention further relates to an assembly comprising a floating wind power platform as defined above and a wind turbine nacelle comprising a generator coupled to a propeller, the wind turbine nacelle being fixed to an upper part of a tower.

[0017] According to some embodiments, the generator is capable of generating a current having a power of more than 10 MW, in particular more than 14 MW.

[0018] The invention will be better understood on reading the following description, given purely by way of example, made with reference to the accompanying drawings in which: [Brief description of the drawings]

[0019] [Figure 1]1 is a schematic diagram of a floating wind power assembly comprising a floating wind power platform according to the present invention, the floating wind power platform comprising a floating structure and a tower. [Diagram 2] 2 is a partial cross-sectional view of the floating wind power platform of FIG. 1 according to one embodiment. [Diagram 3] 2 is a partial cross-sectional view of another embodiment of the floating wind power platform of FIG. 1. [Figure 4] FIG. 2 is a horizontal cross-section of the tower of FIG. 1 according to a first embodiment. [Diagram 5] FIG. 2 is a perspective view of the tower of FIG. 1 according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A floating wind power assembly 10 is shown in FIG.

[0021] The floating wind power assembly 10 can be installed in a body of water 12 .

[0022] Specifically, the water area 12 is, for example, the sea. The body of water 12 resides on the ocean floor 14 . Those skilled in the art will appreciate that if the body of water 12 is a lake, then the ocean floor 14 would be the bottom of the lake.

[0023] As can be seen in FIG. 1, the body of water 12 has a depth D, according to the vertical direction, comprised between 50 m and 1500 m.

[0024] In particular, the floating wind power assembly 10 may be moored to the ocean floor 14 . For this purpose, the floating wind power assembly 10 can be attached to the sea bed 14 via at least one mooring line 16, advantageously three mooring lines 16.

[0025] The floating wind power assembly 10 comprises a floating wind power platform 20 and a wind turbine nacelle 22 .

[0026] The wind turbine nacelle 22 includes a generator 24 coupled to a propeller 26 .

[0027] When the floating wind power assembly 10 is moored to the seabed 14 at an operating base, the propellers 26 are set to rotate to power the generators 24, which then produce electricity.

[0028] The generator 24 is capable of generating a current having a power of more than 10 MW, in particular more than 14 MW.

[0029] As shown in FIG. 1, the floating wind power platform 20 comprises a floating structure 28 and a tower 30 extending from the floating structure 28 .

[0030] The tower 30 extends along a main direction Z. The main direction Z is approximately vertical when the buoyant element 32 is disposed in the body of water 12 .

[0031] The floating structure 28 is capable of floating in the body of water 12 .

[0032] The floating structure 28 comprises a buoyancy element 32 .

[0033] The buoyancy element 32 here comprises three stabilizing columns 33 interconnected by beams. However, the buoyancy element 32 may also include two stabilization columns 33 or more than three stabilization columns 33 . Buoyancy element 32 may also be any type of floating system capable of floating in body of water 12 and supporting tower 30 .

[0034] The floating structure 28 further advantageously comprises a transition section 34 .

[0035] A transition portion 34 protrudes from the buoyancy element 32 .

[0036] Specifically, buoyant element 32 presents an upper surface 36 when buoyant element 32 is disposed in body of water 12 . The transition portion 34 then projects upwardly from the upper surface 36 along the main direction Z.

[0037] The transition section 34 may be cylindrical or frusto-conical in shape.

[0038] The transition portion 34 is advantageously made of steel.

[0039] The transition portion 34 extends along the main direction Z with a length H2 advantageously comprised between 40 cm and 20 m.

[0040] The tower 30 protrudes from the floating structure 28 along a main direction Z.

[0041] As shown in FIG. 2, the tower 30 protrudes from a transition portion 34 of the floating structure 28 along a main direction Z.

[0042] In one variant not shown, the floating structure 28 has no transition section and the tower 30 projects directly from the buoyancy element 32 .

[0043] The tower 30 extends along a main direction Z with a total length H1 comprised between 80 m and 150 m. For example, if the generator 24 provides a power of 10 MW, the overall length H1 is typically equal to 95 m. If the generator 24 provides a power of 15 MW, the overall length H1 is typically equal to 125 m. If the generator 24 provides a power of 20 MW, the overall length H1 is typically equal to 135 m.

[0044] The tower 30 has a cylindrical or frusto-conical shape.

[0045] As shown in FIG. 2, the tower 30 is advantageously secured to the transition section 34 via a bolted flange 42 .

[0046] The tower 30 and the transition section 34 form two axially consecutive components. Each part presents a circular, disk-shaped flange. The bolt holes are disposed in each circular, disk-shaped flange, preferably at regular intervals around the circumference of the flange. Two circular disk shaped flanges face each other and bolts passing through holes secure the two parts 30, 34 together, the bolts connecting with nuts.

[0047] The bolts and nuts are optionally made of stainless steel or advantageously of a composite material. Advantageously, the bolts and nuts are made of the same material as the tower 30 .

[0048] As shown in FIG. 3, in one variation, the tower 30 is grouted to the transition section 34 . Specifically, tower 30 exhibits a clamp-shaped end and is assembled with transition section 34 by deformation of the clamp-shaped end onto transition section 34 .

[0049] The tower 30 extends along the main direction Z in the extension of the transition portion 34 .

[0050] That is, there is a smooth connection and no discontinuities between the tower 30 and the transition portion 34 along the primary direction Z.

[0051] The tower 30 comprises a composite material.

[0052] Advantageously, the tower 30 is made entirely of composite materials.

[0053] A composite material is an assembly of at least two immiscible components, but has a high permeability capacity. Because the properties of the different components complement each other, the new heterogeneous material thus formed exhibits properties that the components do not possess on their own.

[0054] Structural composites generally consist of a reinforcement material and a matrix. The reinforcement is advantageously fibrous or filamentary and provides essential mechanical properties.

[0055] The matrix acts as a binder, protecting the reinforcements from the environment, maintaining them in their initial position and ensuring the transmission of forces. Depending on the nature of their matrix, composite materials can be classified as organic matrix composites, ceramic matrix composites or metal matrix composites.

[0056] In the present invention, the composite material preferably comprises an organic matrix coating an inorganic reinforcement material. The organic matrix is ​​a polymeric material such as a polyolefin, polyamide, polyester or epoxy resin. The organic matrix is ​​preferably selected from among epoxy and polyester resins. The reinforcement is an inorganic material in the form of fibers. Suitable reinforcing materials include short or long glass fibers, carbon nanotubes and / or carbon fibers.

[0057] Advantageously, the composite material is made of polyester and glass.

[0058] In one variant, the composite material is advantageously made of epoxy and glass.

[0059] In a first embodiment of a tower 30 , shown in FIG. 4, the tower 30 has an inner layer 50 and an outer layer 52 .

[0060] Inner layer 50 faces the inside of tower 30 and outer layer 52 faces the outside of tower 30 .

[0061] The inner layer 50 and the outer layer 52 extend along the main direction Z for the entire length H1 of the tower.

[0062] The inner layer 50 is made of steel.

[0063] The outer layer 52 is made of a composite material.

[0064] The outer layer 52 is advantageously made of a single material.

[0065] The single material is advantageously a fibre-reinforced polyester, in particular glass or carbon fibre.

[0066] The width of the inner layer 50 and the width of the outer layer 52 can be adjusted to reduce the natural period of the tower 30 to a target value between the 1P and 3P frequencies.

[0067] The larger the outer layer 52 is relative to the inner layer 50, the shorter the natural period of the tower 30.

[0068] Advantageously, the width of the outer layer 52 is not constant along the height of the tower. The varying widths of the outer layers 52 allow for further tuning of the natural period of the tower 30 .

[0069] In a second embodiment of the tower 30, shown in FIG. 5 , the tower 30 has a lower part 54 that connects to the floating structure 28, an upper part 56 that can support the wind turbine nacelle 22, and an intermediate part 58 that is arranged along the main direction Z between the lower part 54 and the upper part 56.

[0070] The intermediate portion 58 is formed from a composite material.

[0071] Advantageously, the lower portion 54 and the upper portion 56 are made of steel.

[0072] The height of the intermediate section 58 is adjusted to reduce the natural period of the tower 30 to a target value between the 1P and 3P frequencies.

[0073] The longer the intermediate section 58, the shorter the natural period of the tower 30.

[0074] Moreover, the intermediate portion 58 is preferably located in a lower portion of the tower 30 . In other words, the lower portion 54 is shorter in height than the upper portion 56 .

[0075] The intermediate portion 58 is advantageously made of a single material.

[0076] Thus, the intermediate section 58 is free of other materials and mechanical parts in addition to the composite material. The middle section 58 simply has the composite material disposed between the upper section 56 and the lower section 54 .

[0077] The single material is advantageously a fibre-reinforced polyester or epoxy resin, in particular glass, carbon nanotubes or carbon fibres. The fibrous reinforcement is optionally in the form of a woven or non-woven fabric or bulk fibers.

[0078] The single material is optionally coated with a paint to prevent degradation from the environment, particularly ultraviolet radiation and / or salt water.

[0079] In the third embodiment, the first and second embodiments are combined.

[0080] The tower 30 then has a middle section 58 with an inner layer of steel and an outer layer of composite material.

[0081] The natural period is in this case adjusted by adapting both the width of the inner layer and the width of the outer layer, on the one hand, and the height of the intermediate part 58, on the other hand.

[0082] The height of the intermediate portion 58 is advantageously at least 15% of the total length H1 of the tower, in particular at least 30% of the total length H1 of the tower.

[0083] Traditionally, towers 30 are made entirely of steel. However, as explained above, in conventional steel towers, the first natural period of the tower 30 is too close to the 3P frequency.

[0084] Composite materials can be six times stiffer than steel with comparable strength performance.

[0085] The present invention makes it possible to place low stiffness sections in the tower 30 and, by adjusting the amount of composite material in the tower 30, it is possible to reach the target in terms of natural frequency and reduce resonance phenomena and therefore fatigue damage.

[0086] Composite materials may also provide additional structural damping to the assembly 10 .

[0087] Moreover, the composite material avoids the problem of corrosion of the tower 30 .

[0088] However, tower 30 may be provided with a coating, particularly to protect the composite material from ultraviolet radiation and / or salt water, such as in the ocean or salt lakes.

[0089] It appears apparent that the present invention has many advantages.

[0090] Specifically, as explained above, the present invention makes it possible to provide a floating wind power platform having a first natural period sufficiently separated from the 1P frequency and the 3P frequency.

[0091] Specifically, tower 30 including composite materials allows the natural period of the tower to be reduced to an acceptable value.

[0092] Because composite materials are less stiff than steel, the amount of composite material can be adjusted to reduce the natural period of the tower 30 depending on the overall design of the platform 10 and external conditions that may affect the natural period of the tower 30.

[0093] Moreover, the present invention ensures sufficient resistance and integrity of the floating wind power assembly 10 throughout its entire service life.

[0094] Finally, the composite tower 30 is easy to manufacture and simplifies the connection to the floating structure 28 .

[0095] The present invention therefore provides a cost-effective solution to the resonance phenomenon. [Explanation of symbols]

[0096] 10. Floating wind turbine assemblies 12 Water area 14 Undersea 16 Mooring line 20 Floating Wind Power Platform 22 Wind Turbine Nacelle 24 Generator 26 Propeller 28 Floating Structures 30 Tower 32 Buoyancy elements 33 Stable Column 34 Transition Section 36 Top 42 Bolted flange 50 Inner Layer 52 Outer layer 54 Lower part 56 Upper part 58 Middle part

Claims

1. A floating wind power platform (20) capable of being installed in a body of water (12), A floating structure (28) capable of floating in a water body (12); A tower (30) protruding from the floating structure (28) and extending along a main direction (Z), A tower (30) capable of supporting a wind turbine nacelle (22); A floating wind power platform, wherein the tower (30) comprises a composite material.

2. The floating wind power platform (20) of claim 1, wherein the tower (30) has a steel inner layer (50) and a composite outer layer (52).

3. The tower (30), a lower portion (54) for connection to the floating structure (28); an upper portion (56) capable of supporting a wind turbine nacelle (22); and an intermediate portion (58) disposed along the main direction (Z) between the lower portion (54) and the upper portion (56), The floating wind power platform (20) of claim 1 or 2, wherein the intermediate section (58) is formed from a composite material.

4. The floating wind power platform (20) of claim 3, wherein the lower portion (54) and the upper portion (56) are constructed of steel.

5. 5. The floating wind power platform (20) according to any one of claims 1 to 4, wherein the composite material is a fibre reinforced polyester or epoxy resin, in particular glass, carbon nanotubes or carbon fibres, and the fibre reinforcement is optionally in the form of a woven or non-woven fabric or in the form of bulk fibres.

6. The floating structure (28) comprises a buoyant element (32) and a transition portion (34) protruding from the buoyant element (32); The floating wind power platform (20) of any one of claims 1 to 5, wherein the tower (30) is fixed to a transition section (34).

7. The floating wind power platform (20) of claim 6, wherein the tower (30) is secured to the transition section (34) via a bolted flange (42).

8. The floating wind power platform (20) of claim 6, wherein the tower (30) is grouted to a transition section (34).

9. The floating wind power platform (20) according to any one of claims 6 to 8, wherein the transition portion (34) extends along a main direction (Z) with a length (H2) comprised between 40 cm and 20 m.

10. A floating wind power assembly (10), comprising: A floating wind power platform (20) according to any one of claims 1 to 9, a wind turbine nacelle (22) comprising a generator (24) coupled to a propeller (26); A floating wind power assembly comprising a wind turbine nacelle (22) fixed to a tower (30).

11. 11. The floating wind power assembly (10) according to claim 10, wherein the generator (24) is capable of generating a current having a power of more than 10 MW, in particular more than 14 MW.

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