SELF-ADJUSTING MARINE WIND TURBINE WITH TWO ALTERNATORS

Abstract

SELF-ADJUSTING MARINE WIND TURBINE WITH TWO ALTERNATORS The invention relates to a self-adjusting marine wind turbine (1) comprising a floating platform, at least one mast (21) on which is fixed a nacelle (4) comprising a hub (40) with a horizontal axis X and connected to blades (3). It is characterized in that the hub (40) cooperates with a rotor (50) of two alternators (5). This feature allows for a complete redesign of the nacelle structure with the possibility of increasing the overall rotor power. The same power can thus be obtained with smaller alternators. In this way, for a total wind turbine power of 6 MW, each alternator will only be 3 MW, and the diameter will thus be reduced from 7 m to less than 5 m. Figure to be published with the abbreviation: Figure 4

Description

Title of the invention: SELF-ORIENTING MARINE WIND TURBINE WITH TWO ALTERNATORS TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of offshore wind turbines or marine wind turbines and in particular those which are self-orientable. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Offshore wind turbines are installed at sea or in an aquatic environment and must withstand marine conditions which are sometimes difficult.

[0003] While the first offshore wind turbine prototypes were copies of onshore wind turbines with blades connected to a rotating hub with a horizontal axis, they are now adapted for the sea. With current technological developments, we are seeking to increase the size and power. Today, we have reached spans of up to 126m and power outputs of 5MW (mega Watt).

[0004] There are two types of offshore wind turbines: fixed wind turbines, which are generally installed at depths not exceeding 50 m, and floating wind turbines, which are installed at depths beyond 50 m. The floating wind turbine is mounted on a floating platform connected to the seabed by cables. By virtue of its construction, the floating wind turbine is self-orienting or passively orientable, that is to say, it orients itself according to the direction of the wind.

[0005] On the other hand, wind turbines are always mounted in a configuration with the rotor forward, facing the wind, in order to minimize the shadow effect of the tower, which is quite significant in traditional structures. This is why offshore solutions have been developed with a floating platform with 3 or 4 masts instead of a fixed single-tower structure. The entire structure orients passively with the wind, which makes it possible to eliminate the masthead orientation system on the nacelle.

[0006] The current trend is to further increase the span up to 160m and even up to 200m with a power of 8MW up to 12-15MW. The International Energy Agency predicts the need to multiply wind energy production by at least 7 by 2050. To reduce its cost, offshore wind farms with machines of 10-20 MW are envisaged. However, in these power ranges, weight is a strong constraint.

[0007] But these sizes and powers imply an increase in the weight of the structure, the manufacturing cost and the assembly time as well as the difficulty of installation. On the other hand, the production of alternators of such high power leads to complications because of the size of the rotor and the stator to be produced. Summary of the invention

[0008] The invention offers a solution to the problems mentioned above, by making it possible to produce a high-power marine wind turbine but with a nacelle of reasonable dimensions and weight, similar to existing wind turbines.

[0009] The invention relates to a self-orienting marine wind turbine comprising a floating platform, at least one mast on which is fixed a nacelle comprising a hub with a horizontal X axis and connected to blades, it is characterized in that the hub cooperates with a rotor of two alternators. This characteristic allows a complete redesign of the structure of the nacelle with the possibility of increasing the overall power of the wind turbine. The alternators thus have a size that is more easily achievable with a stiffness of the structures which makes it possible to respect the dimensions of the air gap. It is thus possible to obtain the same power with smaller alternators. In this way, for a total power of the wind turbine of 6MW, each alternator will only be 3MW each, the diameter will thus go from 7m to less than 5m.

[0010] Advantageously, the alternators are arranged on either side of the hub. By arranging the alternators on either side of the hub, the balance of the nacelle is not disturbed.

[0011] Advantageously, the wind turbine comprises at least three converging masts. The nacelle with its blades is located between the masts and the alternators on each side, the assembly is thus better balanced.

[0012] Advantageously, the two alternators are symmetrical with respect to a plane perpendicular to the axis of the hub. The alternators being identical by symmetry, the balancing of the loads of the assembly is respected.

[0013] Advantageously, the alternators are independent of each other and each is connected to a converter. The wind turbine is thus still operational in degraded mode, if one of the two alternators or its converter fails. If the wind is weak, it is also possible to operate only one alternator, thus at low load of the wind turbine, the load of an alternator will be doubled and the efficiency will be all the better, compared to an alternator of double the nominal power.

[0014] Advantageously, at least one alternator comprises two independent windings each connected to a converter. This makes it possible to adapt the power of the alternator to the power of the wind. This adaptation is even more precise since the two alternators are independent of each other. Thus, if the electrical chain of a stator winding fails, the electrical chains of the other windings will be operational and will allow the wind turbine to be operated until the fault is repaired.

[0015] Advantageously, one of the alternators includes a parking brake connecting the rotor to the stator. This brake makes it possible to brake or stop the blades if the wind is too strong.

[0016] Advantageously, one of the alternators comprises an asynchronous generator. This asynchronous generator makes it possible to supply the various auxiliaries of the wind turbine rotor with electricity without a system of rings and brushes.

[0017] Advantageously, the wind turbine includes a wireless communication system controlling the alternators. The communication system is therefore simpler to set up.

[0018] Advantageously, each alternator has a power of between 4 and 100W. This results in multi-megawatt or deca-megawatt class power.

[0019] Advantageously, at least one alternator is disconnectable. It is thus possible to disconnect one of the two alternators if necessary.

[0020] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0021] The figures are presented for information purposes only and in no way limit the invention.

[0022] [Fig. 1] is a state-of-the-art wind turbine with a single mast,

[0023] [Fig.2] is a state-of-the-art wind turbine with three masts

[0024] [Fig.3] is a perspective view of a nacelle according to the invention,

[0025] [Fig.4] is a section of the nacelle of [Fig.3] with its blades and masts,

[0026] [Fig.5] is a front view of the nacelle of [Fig.4],

[0027] [Fig.6] is a section of a variant of nacelle according to the invention. DETAILED DESCRIPTION

[0028] The figures are presented for information purposes only and in no way limit the invention.

[0029] In the remainder of the description, the side facing the wind will be called "front" and “back”, the opposite side.

[0030] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0031] The wind turbine 1 of the state of the art, illustrated [Fig.l], is a land-based wind turbine or an offshore wind turbine fixed to the seabed, it comprises a mast 2, three blades 3 connected to a nacelle 4 by a hub 40 and a foot 20 placed on the ground. The blades 3 are placed facing the wind V, the nacelle 4 and the mast behind the blades 3. An alternator 5 is placed in the nacelle 4.

[0032] The second wind turbine 1 of the state of the art of [Fig.2], is a floating wind turbine, it comprises floats 22 connected to each other by beams 220, constituting a floating platform and secured to the ground by cables 23. It has three or four masts 21 each connected to a float 22. The nacelle 4 is fixed to the masts 21. An alternator 5 is arranged in the nacelle 4 at the rear thereof. As the masts 21 are thinner than the single mast of [Fig.l] and these masts 21 are not in a radial orientation to the hub 40 like the blades 3, the blades 3 can be arranged between the masts 21 without them casting shade and disturbing the path of the wind V and generating significant vibrations in the wind turbine.

[0033] As the wind turbine 1 is connected to the seabed by cables 23, it can orient itself according to the direction of the wind V.

[0034] The nacelle 4 of [Fig. 3] comprises an alternator 5 on each side and a hub 40 with axis X. This is made up of a fixed axle 401 and a cage 402 which can rotate around the axle 401. The cage 402 has three openings 400 for placing the blades 3 which will rotate said cage 402. Here, the axle is made up of two half-axles each having a flange 403 allowing them to be bolted together in the central part, which facilitates assembly.

[0035] Each alternator 5 comprises a rotor 50 and a stator 51, the rotor 50 being connected to the cage 402. The stator 51 is integral with the nacelle 4 and the axle 401. The alternators 5 are identical and arranged in a mirror image on each side of the plane of the blades perpendicular to the axis X.

[0036] The axle 401 is hollow, thus constituting a service sheath where a standing person can move around to carry out maintenance. It also houses the converter(s) 52 and the electrical connection cables 53. For example, one converter per independent stator winding can be provided, i.e. one for each alternator if there is only one winding per alternator, or two or three per alternator if there are two or three windings per alternator, or n if there are n windings. The power of the alternators can thus be adjusted according to the power of the wind, by using or not using each alternator winding.

[0037] A parking brake 30 is provided in one of the two alternators 5 between the rotor 50 and the stator 51. It makes it possible to block the rotation of the blades 3 in the event of strong winds or maintenance.

[0038] In the variant of [Fig.6], the axle 401 is replaced by two half-nacelles 4L. Each half-nacelle 41 is connected to a float 22 by at least two masts 21, i.e. a total of at least 4 masts for the wind turbine.

[0039] The blades 3 are fixed to the periphery of an axial cylinder 42 which is connected to the two half-nacelles 41 by bearings 410 which ensure rigid cohesion of the two half-nacelles. The rotors 50 are fixed to each end of the axial cylinder 42. Each stator 51 is integral with a half-nacelle 4L

[0040] The axial cylinder 42 is hollow and comprises three gratings 420 placed on the side opposite each of the blades 3 and connecting the ends of the axial cylinder 42, it is thus possible to access the interior for maintenance when the wind turbine is stopped. There is always one of the gratings 420 horizontal when stopped since at that moment one of the blades is vertical and the other two are below for good balance.

[0041] An orientation system 31 of the blades 3 is placed inside the axial cylinder 42 for “feathering” the blades when the wind is too strong or when a repair or maintenance is carried out. The orientation system 31 of the blades 3 comprises a first toothed wheel 310 cooperating with a second toothed wheel 32 placed on the periphery of the base of the blade 3. The blade 3 is connected to the axial cylinder by a bearing 33.

[0042] This variant has the advantage of allowing a more conventional connection of the blade orientation system through a set of rings (power without asynchronous generator and control signals). It also allows the use of conventional nacelles, hence a lower cost.

Claims

Claims

1. Self-orienting marine wind turbine (1) comprising a floating platform, at least one mast (2, 21) on which is fixed a nacelle (4) comprising a hub (40) with a horizontal X axis and connected to blades (3), characterized in that the hub (40) cooperates with a rotor (50) of two alternators (5), that the hub consists of a hollow axle (401) or a hollow axial cylinder (42) adapted for maintenance by a standing man.

2. Wind turbine (1) according to claim 1 characterized in that the alternators (5) are arranged on either side of the hub (40).

3. Wind turbine (1) according to one of the preceding claims, characterized in that it comprises at least three converging masts (21).

4. Wind turbine (1) according to one of the preceding claims, characterized in that the two alternators (5) are symmetrical with respect to a plane perpendicular to the axis X of the hub (40).

5. Wind turbine (1) according to one of the preceding claims, characterized in that the alternators (5) are independent of each other and each is connected to a converter (52).

6. Wind turbine (1) according to one of the preceding claims, characterized in that at least one alternator (5) comprises two independent windings each connected to a converter (52).

7. Wind turbine (1) according to one of the preceding claims, characterized in that one of the alternators (5) comprises a parking brake (30) connecting the rotor (50) to the stator (51).

8. Wind turbine (1) according to one of the preceding claims, characterized in that it comprises a wireless communication system controlling the alternators (5).

9. Wind turbine (1) according to one of the preceding claims, characterized in that each alternator (5) has a power of between 4 and 10 MW.

10. Wind turbine (1) according to one of the preceding claims, characterized in that at least one alternator (5) is disconnectable.

11. Wind turbine (1) according to one of the preceding claims, characterized in that one of the alternators comprises an asynchronous generator.

Images