FR3086351A1 - FLOATING DYNAMIC WIND TURBINE IN STABLE LACE - Google Patents

Abstract

The invention relates to an energy production assembly (1) in a marine environment, comprising: - anchoring means (2) intended to be secured to a seabed (3); - a floating wind turbine (4); - connecting means (8) of the floating wind turbine (4) to the anchoring means (2) allowing movement of the floating wind turbine (4) around the anchoring means (2), characterized in that the connecting means (8) comprise: - a first element (811) rotatably mounted on the anchoring means (2) and pivotally mounted on the floating wind turbine (4) at a first point A; - A second element rotatably mounted on the anchoring means (2) and pivotally mounted on the floating wind turbine (4) at a second point B, defining with the first point A a segment AB. the first element (811) being separated from the second element by a spacing E measured on the floating wind turbine (4), such that 0.2 ≤ E / D ≤ 2, where D is the distance measured between the anchoring means (2) and the center of the AB segment.

Description

Floating wind turbine with stable yaw dynamics

The field of the invention is that of the design and manufacture of means of energy production in the marine environment.

More specifically, the invention relates to an assembly for producing energy in a marine environment which includes a wind turbine of the self-orienting type, that is to say capable of moving as a function of the direction of the wind.

To allow the production of renewable energy wind turbines, which use the force of the wind, are commonly used.

According to a conventional design, wind turbines consist of a mast on which is mounted a turbine provided with a propeller and a unit for transforming the movement of the propeller into an electric current.

Wind turbines are generally installed in cultivated fields or in dedicated spaces, in the form of wind farms.

However, for residents living near wind turbines, the latter have many disadvantages.

First, wind turbines generate noise during operation. This noise is particularly disturbing when the wind turbines operate at night while local residents wish to sleep.

In addition, although efforts have been made to make them aesthetic, the wind turbines form a large mass distorting the landscapes.

In addition, the space required for the installation of an onshore wind turbine is important. Consequently, it may be impossible to install an onshore wind turbine at certain locations or a limit on the number of onshore wind turbines to be installed may be detrimental to the power generation capacity.

Finally, wind conditions may not be optimal on land. On the other hand, it has been shown that at sea, the winds are stronger and more regular, which is beneficial for the production of electricity.

To limit nuisance to residents and improve electricity production capacity, wind turbines intended to be installed at sea have been designed.

There are several types of marine wind turbines.

The first type concerns so-called conventional marine wind turbines, that is to say wind turbines such as those which are installed on land, but which are slightly modified to be able to be installed at sea.

The wind direction can change, this first type of wind turbine includes a turbine mounted movable on the mast so as to adapt to the wind direction.

However, the turbine constitutes a significant weight at the top of the wind turbine, which consequently generates a considerable lever arm and causes significant tilting stresses. It is therefore necessary to provide an anchoring structure for the wind turbine which must withstand the constraints linked to the wind and the weight of the turbine.

To date, the majority of offshore wind turbines, based on the seabed, with the exception of a few prototypes of floating wind turbines according to the second type and the third type, described below. The mast of marine wind turbines therefore most often rests on a metal tube deeply sunk into the submarine underground and more rarely on a metallic lattice structure called a "jacket".

Marine wind turbines of this first type are then generally very heavy and their installation, including the anchoring structure, can be long and tedious.

Floating marine wind turbines are used to exploit huge marine expanses. Unlike the above-mentioned fixed marine wind turbines, floating wind turbines can be installed beyond 50 m in depth, and assembly between the turbine and the foundations can advantageously be carried out on land and not at sea where conditions are more difficult.

Floating wind turbines are maintained on their production site using anchor systems.

These anchor systems for the wind turbine must withstand current and extreme conditions. They are generally composed of anchors (drag anchor, suction anchor, buried plates, or dead weight), anchor lines (chain, wire rope, synthetic materials such as polyester, HPME or even polyamide).

A second type concerns wind turbines similar to the first type but carried by a floating structure connected to the seabed. In production, wind turbines of the second type are subject to currents and swell which can induce a yaw angle at the wind turbine, that is to say a rotation of the floating wind turbine with respect to a vertical axis.

To combat this yaw angle, floating wind turbines of the second type include an electrical yaw adjustment system. For example, electric motors or a leeway system allows the turbine to rotate relative to the mast in order to position the axis of rotation of the turbine propeller in the axis of the wind.

In order to improve the structural strength of floating wind turbines, the patent document published under the number EP2 986 848 describes a third type of floating wind turbine which comprises a floating structure which carries a wind turbine with a horizontal axis using several arms . The turbine nacelle is fixed relative to the floating structure of the floating wind turbine so that it can no longer orient itself facing the wind independently of the floating structure in order to compensate for the yaw angle due to the forces of the sea In summary, it is the whole of the floating wind turbine which is oriented facing the wind, turning around an anchoring means such as a buoy or a reel.

This third type therefore relates to so-called self-winding marine wind turbines.

These wind turbines are generally smaller and lighter than those of the first type and the second type, and include a floating structure carrying the turbine. The floating structure is attached to anchoring means, integral with the seabed, and pivots around them to position themselves in the best conditions of productivity depending on the wind direction.

During its operation, the floating structure is subjected to forces exerted by the sea. More particularly, the structure can be driven in displacement by the currents or the swell.

In addition, the wind also influences the positioning and movement of the floating wind turbine, in particular by exerting a thrust force on the turbine propeller.

The forces exerted by the sea and the wind can cause a movement of the fish tail of the wind turbine compared to the anchoring means.

This phenomenon is known and observed on ships at anchor such as tankers, freighters, or even smaller units. Subjected to wind and swell, we observe in certain conditions an unstable phenomenon in which the ship moves swerving and in yaw (lateral displacement compared to an Oxyz reference point secured to the ship with Ox going from the stern to the bow, Oy going from starboard to port, and Oz to the sky).

In the case of a floating wind turbine, this fishtail movement is detrimental to the productivity of the wind turbine on the one hand, and to the connection means between the wind turbine and the anchoring means on the other hand, and finally the fatigue of the turbine blades, which are subjected to acyclic forces.

Indeed, the propeller, and in particular a plane formed by the propeller, must be normal to the wind vector in order to optimize the efficiency and thus the electrical production. Otherwise, the incidence of the propeller blade profile varies during rotation around the axis of the propeller, which induces variable loads which increase the fatigue of the materials and cause a loss of efficiency. aerodynamic.

In order to guarantee a good production yield, and to limit premature wear of the floating wind turbine, a stable dynamic of the floating wind turbine is then sought.

In other words, it is sought that the floating wind turbine is continuously oriented facing the wind, and more particularly that the axis of rotation of the turbine propeller is continuously parallel to the direction of the wind.

For this there are dynamic solutions which aim to counter the movements of the sea and the wind, these dynamic solutions for example using motors moving the floating wind turbine contrary to the forces it undergoes.

When the stable dynamic is not reached, we say that the floating wind turbine is in unstable dynamics.

Furthermore, the connection means can be stretched and relaxed as the fish tail moves, which generates stresses in the connection means, constraints which may ultimately lead to a rupture of the connection means, or at least to their premature wear.

The invention particularly aims to overcome the drawbacks of the prior art.

More specifically, the invention aims to propose a set of energy production in a marine environment, the dynamics of which are stable whatever the wind, swell and current conditions. This allows in particular that the plane of the he propeller is perpendicular to the wind direction, that the electric production is maximized contrary to the fatigue of the blades which is then minimized.

The invention also aims to provide such an assembly making it possible to reduce fatigue in the connection means between the anchoring means and the wind turbine.

The invention further aims to provide such an assembly which is simple to operate and autonomous.

These objectives, as well as others which will appear subsequently, are achieved thanks to the invention which relates to a set of energy production in a marine environment, comprising:

- anchoring means intended to be secured to a seabed;

- a floating wind turbine;

- means for connecting the floating wind turbine to the anchoring means authorizing a displacement of the floating wind turbine around the anchoring means, characterized in that the connection means comprise:

- A first element rotatably mounted on the anchoring means and pivotally mounted on the floating wind turbine at a first point A;

a second element rotatably mounted on the anchoring means and pivotally mounted on the floating wind turbine at a second point B, defining with the first point A a segment AB, the first element being separated from the second element by a spacing E measured on the floating wind turbine, such as 0.2 <E / D <2, where D is the distance measured between the anchoring means and the center of the segment AB.

The connecting means thus configured make it possible to obtain a controlled fish tail movement of the wind turbine around the anchoring means. This control is particularly advantageous in that the movement of the fish tail causes movement of the wind turbine as it is positioned in the axis of the wind and therefore in optimal production conditions.

In addition, the value range of the E / D ratio makes it possible to conserve flexible type of connection means while maintaining good overall productivity.

Preferably, the E / D ratio is equal to 0.5.

Such a value allows the wind turbine to quickly follow the direction of the wind as it evolves. In addition, this makes it possible to obtain a stable movement dynamic, as opposed to swerving movements and parasitic laces linked to an instability of the anchoring system, or of the wind turbine displaced by the swell, the wind or the current. In the case of a direct action on the wind turbine, the wind, the swell and the current then act either on the float or on the turbine.

Advantageously, the first element and the second element are connected to the anchoring means at a common point.

Such a common point of connection of the first element and of the second element to the anchoring means makes it possible to conserve the movement of gyration of the floating wind turbine only with respect to the anchoring means.

In other words, the pivoting wind turbine can only pivot around the anchoring means, which guarantees its optimal orientation.

According to a preferred embodiment, the first element and the second element are each connected to the floating wind turbine by a pivot connection.

The first element and the second element may, in a first embodiment, be made of flexible synthetic materials, such as polyester lines, and preferably of polyamide to absorb the forces. In addition, they can also incorporate portions of elastomeric material in order to further absorb the stresses.

In a second embodiment, the first element and the second element may be substantially rigid beams made for example of steel.

The movement of the floating wind turbine relative to the first element and to the second element is thus limited so as to ensure the correct positioning of the floating wind turbine.

Indeed, the rotation of the floating wind turbine around the connection of the first element and / or the second element with the floating wind turbine is eliminated, or at the very least limited.

Thus, the positioning of the floating wind turbine is carried out only around the anchoring means, which improves the stabilization of the yaw dynamics of the wind turbine.

Advantageously, the anchoring means include:

- a first member secured to a seabed and around which the floating wind turbine is intended to pivot;

- A second member rotatably mounted relative to the first member, the first member and the second member being integral with the second member.

Such a design of the anchoring means is particularly advantageous in that it makes it possible to have a first member which remains fixed while the second member ensures the orientation of the floating wind turbine. Thus, it can be ensured both of the good fixing of the anchoring means to the seabed and, at the same time, of the good self-orientation of the floating wind turbine as a function of weather conditions, and in particular of the wind direction.

According to a preferred embodiment, the first member is a float and the second member is a ring surrounding the float.

Such a design of the anchoring means is simple and economical both in terms of design, manufacturing or installation. In addition, this limits the time and frequency of maintenance of the anchoring means while allowing their autonomy in operation.

Advantageously, the connecting means comprise a third element mounted for rotation on the anchoring means and connected to the floating wind turbine at a third point C.

This third element improves the stability of the floating wind turbine during its operation. Indeed, if the first two elements control the floating wind turbine rotating around the anchoring means, the third element controls the tilting linked to the force of the wind.

Preferably, the third point C is distant from the segment AB, for example located on a turbine of the floating wind turbine.

Thus, we ensure a resumption of the forces applied to the floating wind turbine by the wind in "the highs". In other words, by having a third point C as high as possible relative to the surface of the sea, the control of the rotation of the floating wind turbine because of the force of the wind is improved. In particular, this is applicable for a floating wind turbine such as that described in the patent document published under the number EP2 986 848, for which point C can be positioned at any point of the aerial structure, in particular on the legs connecting the structure floating in the turbine nacelle.

Other characteristics and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and nonlimiting example, and of the appended drawings among which:

- Figure 1 is a schematic side view of an energy production unit in the marine environment, according to the invention;

- Figure 2 is a schematic top view of a wind turbine of the entire energy production in the marine environment, according to the invention, showing the connecting means between the floating wind turbine and the anchoring means of the floating wind turbine;

- Figure 3 is a schematic perspective view from above of the anchoring means according to an alternative embodiment.

In Figure 1 is shown a set of energy production 1 in the marine environment, according to the invention.

The power generation set 1 includes:

- anchoring means 2 intended to be secured to a seabed 3;

- a floating wind turbine 4 of the self-orienting type.

The anchoring means 2 comprise a buoy 21 and an anchoring device 22 of the buoy 21 to the seabed 3. As an indication, the buoy has a diameter of 66 m and a height of 58 m.

The floating wind turbine 4 is a wind turbine with a power of 12 MW which includes:

- a floating structure 5;

- an aerial structure 6 mounted on the floating structure 5;

- a turbine 7 carried by the aerial structure 6.

The floating structure 5 comprises at least three floats 51, and in this case four floats 51.

The floats 51 are connected to each other by a trellis 52 formed of beams 521, for example of metal beams 521.

The aerial structure 6 comprises four legs 61. Each leg 61 has a first end 62 secured to one of the floats 51 and a second end 63 secured to the turbine 7.

The turbine 7 comprises a propeller 71 and a nacelle 72 on which the propeller 71 is mounted for rotation about an axis X of rotation.

Generally, the propeller 71 is composed of a central hub on which the blades are rotatably mounted. The blades are independent of each other to allow their orientation in real time if necessary, in particular in order to vary the resistance of the propeller 71 to the wind and therefore the torque of the turbine 7. For the sake of clarity, we speak, after a propeller 71 rather than a central hub and blades assembly.

As illustrated in FIG. 1, the turbine 7 is secured to the aerial structure 6 by cooperation of the nacelle 72 with the second end 63 of the legs.

Finally, the floating wind turbine 4 is connected to the anchoring means 2 by connection means 8, and more particularly by moorings 81.

The moorings 81 allow that, during its operation, the floating wind turbine 4 can rotate around the buoy 21 of the anchoring means 2 to position itself in a wind direction V (illustrated in FIG. 1 by arrows).

In other words, the buoy 2 forms an axis of rotation around which the floating wind turbine 4 rotates to produce energy according to the wind direction.

Moorings 81 include:

- A first element 811 rotatably mounted on the anchoring means 2 and pivotally mounted on the floating wind turbine 4 at a first point A;

a second element 812 rotatably mounted on the anchoring means 2 and pivotally mounted on the floating wind turbine 4 at a second point B, defining with the first point A a segment AB.

Advantageously, the first element 811 and the second element 812 of the moorings 81 are each linked to the floating wind turbine and to the anchoring means by ball joints. Thus rotational mounting is ensured, but in addition, new degrees of freedom are added to it, thereby limiting fatigue and premature wear of the moorings 81.

According to a preferred embodiment, the first element 811 and the second element 812 are each made of polyamide and have a diameter of 160 mm.

The first element 811 is separated from the second element 812 by a spacing E measured on the floating wind turbine 4, such that 0.2 <E / D <2, where D is the distance measured between the anchoring means 2 and the center of segment AB.

Advantageously, it will be preferred that E / D is equal to 0.5.

As illustrated in FIG. 2, the first element 811 and the second element 812 are connected to the anchoring means 2 at a common point 23.

By way of example, the common point 23 is for example formed by a loop to which the moorings 81, and in particular the first element 811 and the second element 812, are connected.

As illustrated in FIGS. 1 and 2, the buoy 21 of the anchoring means 2 comprises:

- A first member 211 secured to the seabed 3 and around which the floating wind turbine 4 is intended to pivot;

- A second member 212 rotatably mounted relative to the first member 211.

One of the first member 211 and of the second member 212 carries the loop of the common point 23 which allows the attachment of the floating wind turbine 4 as explained below.

Preferably, and as illustrated in FIGS. 1 and 2, the first member 211 is a float and the second member 212 is a ring surrounding the float.

In operation, the ring rotates around the float following the movement of the floating wind turbine 4 which seeks to orient itself, independently according to the wind conditions.

According to an advantageous embodiment, illustrated in FIG. 3, a beam 213 can be rotatably mounted on the second member 212, along an axis substantially perpendicular to that of extension of the first member 211, the beam 213 ensuring the junction between the moorings 8 and the mooring system 2. The moorings 8 are therefore connected to the mooring means by means of this beam 213 (also known in the maritime environment according to the English name "yoke"). In addition, the beam 213 advantageously comprises an end opposite to the buoy 21, this end forming the common point 23 allowing the attachment of the floating wind turbine 4 via the moorings 81.

Preferably, the moorings 81 are flexible moorings, for example ends or chains. In particular, the moorings 81 may be made of polyamide, a material which exhibits a viscoelastic behavior making it possible to dampen the oscillations of the float excited by the waves.

However, in an alternative embodiment, the moorings 81 may consist of rigid elements such as beams, or of a combination of rigid elements and flexible moorings.

The object of the moorings 81 is to ensure a stable yaw dynamic but also to dampen the movements of the floating wind turbine 4 and the force cycles so that the anchoring device 22 of the buoy 21 does not have to fulfill this function, but only to resume the averaged forces.

The first element 811 and the second element 812 are each connected to the floating wind turbine 4 by a pivot link. The two elements 811, 812 can in particular have, at their end by which they are connected to the floating wind turbine 4, a ring intended to be crossed by the loop 23.

The first element 811 and the second element 812 are thus integral with the second member 212 which carries the loop 23.

Referring to Figure 1, the moorings 81 of the connecting means 8 comprise a third element 813 rotatably mounted on the anchoring means 2 and connected to the floating wind turbine 4 at a third point C.

The third point C is distant from the segment AB and makes it possible to limit, or even prohibit the tilting of the floating wind turbine 4 because of the force of the wind.

For this, the third point C is advantageously located on the turbine 7 of the floating wind turbine 4. More particularly, the third point C is located at the nacelle 72, for example directly in the center thereof by a ball joint . Thus, there is no risk that the blades of the propeller 71 will abut against the moorings 81 and in particular against the third element 813, which would risk damaging the blades of the propeller 71 and / or the third element 813 of the moorings 81.

Claims (9)

1. Energy production unit (1) in the marine environment, comprising: - anchoring means (2) intended to be secured to a seabed (3); - a floating wind turbine (4); - connecting means (8) of the floating wind turbine (4) to the anchoring means (2) allowing movement of the floating wind turbine (4) around the anchoring means (2), characterized in that the connecting means (8) include: - A first element (811) rotatably mounted on the anchoring means (2) and pivotally mounted on the floating wind turbine (4) at a first point A; - a second element (812) rotatably mounted on the anchoring means (2) and pivotally mounted on the floating wind turbine (4) at a second point B, defining with the first point A a segment AB. the first element (811) being spaced from the second element (812) by a spacing E measured on the floating wind turbine (4), such as 0.2 <E / D <2, where D is the distance measured between the means anchor (2) and the center of the segment AB. 2. Assembly according to claim 1, characterized in that the E / D ratio is equal to 0.5. 3. Assembly according to claim 1 or claim 2, characterized in that the first element (811) and the second element (812) are connected to the anchoring means (2) at a common point (23). 4. Assembly according to any one of the preceding claims, characterized in that the first element (811) and the second element (812) are each connected to the floating wind turbine (4) by a pivot connection. 5. Assembly according to any one of the preceding claims, characterized in that the anchoring means (2) comprise: - A first member (211) secured to a seabed (3) and around which the floating wind turbine (4) is intended to pivot; - A second member (212) rotatably mounted relative to the first member (211), the first member (811) and the second member (812) being integral with the second member (212). 6. Assembly according to the preceding claim, characterized in that the first member (211) is a float and the second member (212) is a ring surrounding the float. 7. Assembly according to any one of the preceding claims, characterized in that the connection means (8) comprise a third element (813) mounted for rotation on the anchoring means (2) and connected to the floating wind turbine ( 4) at a third point C. 8. An assembly according to claim 7, characterized in that the third point C is distant from the segment AB. 9. An assembly according to claim 7 or claim 8, characterized in that the third point C is located on a turbine (7) of the floating wind turbine (4).