FR2970748A1 - Method for realizing maintenance operations i.e. replacement of heavier parts, of floating wind turbine device of off-shore wind energy production system, involves positioning floating wind turbine device on maintenance device - Google Patents

Abstract

The method involves disconnecting a sinkable float (20) of anchor line systems (3a, 3b, 3c) and an electrical cable (40). A floating wind turbine device (1) is transferred from a production site to a maintenance device (5) by towing. The turbine device is positioned on the maintenance device, so that the turbine device is supported by the maintenance device. The maintenance device is fixed at the bottom (F) of a sub-marine. The turbine device is positioned on a lifting system (6) of the maintenance device. The turbine device is positioned above a movable immersed support (61). An independent claim is also included for a system for producing off-shore wind energy.

Description

The present invention relates to a method for carrying out maintenance operations on a floating wind turbine device belonging to a fleet of floating wind turbine devices, and a corresponding offshore wind power generation system. s Offshore wind power generation systems are known including a fleet of several offshore wind turbine devices, each wind turbine device having a servo-submersible float and at least one wind turbine mounted on said float, a system an anchor line for anchoring the float to the Io submarine bottom on a production site, and at least one electrical cable for connecting the wind turbine to an electrical distribution network, for example via a power cable submarine. This type of floating wind turbine device allows the implantation of wind turbines at sites further away from the coasts, with significant depths, for example of more than 50 meters, where the implantation of fixed wind turbines on a foundation laid on the ground. underwater background can not be considered for technical reasons or costs. The remoteness of the coasts notably makes it possible to reduce visual and sound impacts for the shore, and also guarantees a stronger and more regular wind, allowing better energy production. To date, in order to carry out maintenance operations on floating wind turbine devices, technicians are brought on board floating wind turbine devices by boat or by hoist. The operations performed on the wind turbine devices anchored on their production site mainly concern light maintenance operations, that is to say not requiring the replacement of large parts. For heavier maintenance operations, including the replacement of large parts, self-raising type barges, conventionally known as "jack-up" systems conventionally used for fixed offshore wind turbines, can not be used for floating wind turbine because of the excessive depths, as well as the movements of the floating wind turbine devices. Other barge type floating crane systems, conventionally called "bigues" can not also be envisaged, in the context of regular or punctual use, because of their excessive costs. For these 2 operations

maintenance, floating wind turbine devices are towed to a port area and placed in drydock. Due to the remoteness of the fleet and the constraints for towing inside the ports, particularly related to the draft of floating wind turbine devices, these transfer operations to a port area are long, tedious and expensive. and risky. The object of the present invention is to propose a solution to overcome the aforementioned drawbacks. For this purpose, the present invention provides a method for carrying out maintenance operations on a floating wind turbine device belonging to a fleet of floating wind turbine devices, said floating wind turbine device comprising a float, preferably of the serai-submersible type, and preferably equipped with a ballast system, ls - at least one wind turbine mounted on said float, comprising blades, a rotor, preferably having a horizontal axis of rotation, a nacelle and a mast, the mast being assembled to said float, - an anchor line system for anchoring the float to the sea bed at a production site; At least one electrical cable for connecting the wind turbine to an electrical distribution network, for example via a submarine power cable, characterized in that it comprises: a) disconnection of said float from the line system; anchoring and electrical cable, preferably disconnecting the electrical cable, then disconnecting the anchor line system, b) towing the floating wind turbine device from its production site to a maintenance device, disposed near or in the vicinity of the fleet of floating wind turbine devices; c) positioning the wind turbine device on the maintenance device so that the wind turbine device is supported by the maintenance device, and stabilized to perform maintenance operations. According to the invention, a maintenance device fixed to the bottom is provided at sea near the wind turbine equipment park, or within the park itself. To carry out maintenance operations on a device, particularly heavy operations, it is towed to the maintenance device and is positioned on the latter so that the wind turbine device is stable for carrying out maintenance operations. safely. For example, the maintenance device is installed adjacent to the park, at a distance from the park of less than 20 nautical miles, preferably at a distance of less than 10 miles, so that the towing of a device A floating wind turbine between the production site and the maintenance device is carried out in less than two hours, preferably in less than one hour, for example at a speed of the order of 4 knots. The presence at sea of such a maintenance device is particularly interesting for those production sites conventionally installed more than 20 miles from a port likely to accommodate such wind turbine devices, generally at more than 40 miles ls from such a port. Maintenance operations can thus be carried out quickly, close to the production site, in good safety conditions, without requiring a long, tedious and expensive transfer to a port area. After carrying out maintenance operations, the method according to the invention comprises: - withdrawing the wind turbine device from the maintenance device, so that said wind turbine device floats again, - towing the wind turbine device to its production site, - the connection of the wind turbine device to its anchor line system and its electrical cable. According to a feature, said maintenance device of steps b) and c) is non-floating, fixed to the seabed, thus guaranteeing a perfect stability of the wind turbine device during maintenance operations. By way of example, the wind farm is installed at a depth of more than 50 meters (m), and the maintenance device is installed next to the park at a depth of less than 50111, preferably at a depth of less than 50 meters. from 30 m. 4

According to one embodiment, the positioning step c) comprises a lifting operation of the wind turbine device by means of a lifting system of the maintenance device. According to one embodiment, for this lifting operation, step c) may comprise the positioning of the wind turbine device over a mobile immersed support, and the raising of said mobile immersed support by lifting means for lift the wind turbine device. Advantageously, the positioning step c) comprises - a deballasting of the float, - the positioning of the wind turbine device above said immersed mobile support, - a possible ballasting of the float to put the wind turbine device on said mobile support immersed, and - the rise of said immersed mobile support with a deballasting ls simultaneous, and progressive float. Said immersed mobile support can be formed of a submerged frame operated by cable systems, winch and / or jack, or a ballastable / deballastable box to lift the device by buoyancy. As a variant, the lifting operation is carried out by means of arms engaging float structure elements, arranged for example above sea level. According to another embodiment, step c) of FIG. positioning comprises 25 - a deballasting of the float, - the positioning of the wind turbine device over a submerged support, preferably fixed, of the maintenance device, - the ballasting of the float to put the wind turbine device on said support immersed. Positioning step c) may include docking the wind turbine device to the maintenance device prior to the lifting operation and / or the ballasting operation to place the wind turbine device on the fixed immersed support. The present invention also relates to an offshore wind energy production system, for the implementation of the method as described above, comprising a fleet of offshore wind turbine devices, each wind turbine device comprising a float, preferably of the serai-submersible type, and at least one wind turbine mounted on said float, an anchoring line system, an electric cable for connecting the wind turbine to an electrical distribution network, characterized in that further comprises a maintenance device, mounted fixed on the seabed, near the fleet of floating wind turbine devices or in said park, formed of one or more platforms, and provided with support means able to withstand the least one floating wind turbine device disconnected from its anchoring line system and, preferably, its electrical cable, said maintenance device being preferably equal to maintenance means for performing maintenance operations on floating wind turbine devices, particularly coin storage areas, a heliport platform or maintenance tools, such as a crane for removal and mounting large parts of the wind turbine device carried by the maintenance device, or handling systems for moving parts on the maintenance device. The heliport platform notably provides a landing and refueling area near the park for the helicopters responsible for hoisting the technicians on the floating wind turbine devices. The maintenance device is preferably also equipped with energy production means necessary for the operation of the various equipment present on the maintenance device.

Preferably, the maintenance device is fixedly mounted on the sea floor. According to one embodiment, said maintenance device comprises at least one lifting system comprising a mobile immersed support constituting said support means, able to be moved by lifting means between a low position in which at least one device wind turbine is adapted to be disposed above said movable immersed support, substantially without contact with the latter, and a high position in which said wind turbine device is adapted to be carried by said movable immersed support. Said mobile immersed support may comprise a frame, said lifting means comprising cable systems and / or winch systems and / or 6-jack systems, preferably comprising cables connecting said frame to winch systems and / or of jacks, possibly with a system of pulleys. Preferably, said lifting means comprise cable jack type jack systems. In an alternative embodiment, said mobile immersed support comprises a ballastable caisson or buoy, said lifting means comprising a pump system for ballasting / unpacking said caisson. According to one embodiment, the float of the floating wind turbine device is of the serai-submersible type, preferably comprising at least three columns. According to one embodiment, the float of the wind turbine devices comprises a ballast system, said float comprising for example at least three external columns connected to each other by ls of the connecting elements, said columns forming ballasts. According to another embodiment, the support means comprise a fixed immersed support on which at least one wind turbine device is able to land by deballasting then ballasting said float. According to another embodiment, said maintenance device further comprises an electrical substation to which the electrical cables of the wind turbine devices are connected, preferably via one or more power cables arranged on the seabed, said electrical substation comprising transforming means for transforming the electrical energy delivered by the wind turbines, in particular to bring it to a higher voltage, for its transport towards the distribution network. According to one embodiment, the system further comprises a work barge comprising at least one attachment point for attaching anchor lines of a wind turbine device, upon disconnection of said wind turbine device from said lines. anchoring on the production site, said barge preferably comprising at least one attachment point for fixing the electric cable. The invention will be better understood, and other objects, details, features, and advantages will become more clearly apparent from the following detailed explanatory description of particular embodiments of the present invention, with reference to the accompanying schematic drawings. , in which: FIG. 1 is a diagram illustrating a wind energy production system comprising several floating wind turbine devices and a maintenance device; - Figure 2 is a schematic perspective view of a floating wind turbine device; FIG. 3 is a schematic side view of a floating wind turbine device and a maintenance device according to a first embodiment; - Figure 4 is a schematic top view of the maintenance device of Figure 3; - Figures 5A and 5B are side views of the maintenance device, respectively with the low lift system ls and the lifting system in the high position; FIGS. 6A to 6D are schematic side views of a floating wind turbine device illustrating various operations of the disconnection or electrical disconnection step; FIG. 7 is a schematic top view of the floating wind turbine device illustrating the step of disconnecting the mooring lines; FIG. 8 is a schematic view from above of the floating wind turbine device illustrating the step of transfer by towing; FIG. 9 is a schematic view from above of the floating wind turbine device illustrating the positioning of the wind turbine device on the maintenance device and its mooring; FIG. 10 is a schematic side view of a floating wind turbine device and a maintenance device according to a second embodiment; Figure 11 is a schematic top view of the maintenance device of Figure 10; - Figure 12 is a schematic side view of a maintenance device according to a third embodiment; FIG. 13 is a schematic side view of a floating wind turbine device according to a fourth embodiment;

Figure 14 is a schematic top view of a floating wind turbine device according to a fifth embodiment, including a retractable arm lift system, said arms being in the retracted position; and, - Figure 15 is a view similar to that of Figure 14, the arms being in the deployed position. With reference to FIG. 1, the offshore wind power generating system comprises a fleet of several floating wind turbine devices 1 and a maintenance platform device 5 placed at sea near the park. With reference to FIG. 2, the floating wind turbine device 1 comprises a wind turbine 10 and a hull or float 20 of the semi-submersible type. The wind turbine 10 comprises, in known manner, blades 11, a hub or rotor 12 with a horizontal axis of rotation, a nacelle 13 and a mast 14. The wind turbine further comprises a generator, placed in the nacelle to produce energy. electrical power from the rotational movement of the blades, electric conversion means for converting the electrical energy produced by the generator into an electrical energy having a given frequency, and electrical transformation means for transforming the voltage between the phases of the electrical energy delivered by the conversion means to bring it to a higher voltage, for example of the order of 33 000 volts. The electrical conversion means and the electrical transformation means are arranged in the nacelle or the mast, or on the float inside a container, as described in the French patent application, filed in the name of the applicant, on December 27, 2010, under No. 1061260, entitled "Offshore floating wind turbine with special provision for means for conversion and / or electrical conversion", said container being able to be on a constituent element of the float above the waterline, for example on the top of one of the columns or on an upper connecting element of the float, disposed in a float element, for example in one of the columns, or be formed by one of the components of the float or by a part of a constituent element of the float, for example by the upper part of a column. In the present illustrated embodiment, the float 20 comprises three cylindrical vertical columns 21a, 21b, 21c external, arranged at regular angular spaces around the vertical central axis of the float, and interconnected by elements of s liaison. The float is for example that described in the French patent application, filed in the name of the applicant on November 22, 2010, under No. 1059603, and entitled "Offshore wind turbine device with special serai-submersible float". The connecting members comprise fully submerged horizontal beams or horizontal pontoons 22, upper beams 23, also called bridges or bridges, and a central junction piece. The lower pontoons 22, for example of rectangular section, connect the columns two by two in the lower part, in particular at lower portions of said stabilization portion 211, of larger section. The beams ls 23 upper, for example of rectangular section are arranged in the upper part of the columns. Each upper beam extends radially from the central axis of the float to one of the columns. The three beams 23 are connected at the central axis to the junction piece 24. A vertical intermediate piece 27 is assembled to the junction piece 24 for supporting the mast 14 of the wind turbine. For better structural strength and rigidity, the columns 21a, 21b, 21c, the pontoons 22, the beams 23 and the intermediate piece 27 are interconnected with a lattice structure comprising primary struts and secondary struts 26. Alternatively, the float comprises more than three outer columns, and / or a central column on which the mast of the wind turbine rests. As schematically illustrated in Figure 3, the columns form ballasts. Preferably, the interior volume of the columns is compartmentalized to form separate ballast compartments. Each pontoon may also constitute a separate ballast compartment. Piping and pump systems are provided for the loading and unloading of ballast water, as well as control and monitoring systems for controlling the pipeline systems. These systems are installed on the wind turbine device and / or 2970748 on a vessel, particularly a tug for the transfer of wind turbine devices. The device also comprises a catenary anchoring system or anchor line system, for the positioning of each floating wind turbine device at the production site, said system being for example designed for a range of depths between 50 and 300. m. In the illustrated embodiment, this anchoring system comprises three anchor lines 3a, 3b, 3c. The anchor lines may comprise chains and / or flexible cables, optionally equipped with weights arranged discretely along the anchor line, and anchors. Each anchor line is anchored to the seabed F via an anchor, and is connected to a column, the deployment angle of each anchor line being about 120 °. The catenary anchoring system shall prevent the floating wind turbine from deviating from its nominal position by counteracting the combined action of the average forces induced by the wind turbine, constant forces induced by the wind acting on the mast and the float , constant forces induced by the current acting on the float and average drifting forces due to the swell. On the other hand, the anchoring system must allow, without constraining them, the first order movements induced by the swell and the wind turbine, even under extreme conditions. The wind turbine device is connected by an electric cable, said umbilical cable or dynamic cable, to a submarine power cable 41 for conveying electrical energy produced by the wind turbine to the electrical distribution network. The umbilical cable is connected by an end 40a, for example at the level of a column, to an electric cable which is connected to the transformation means of the wind turbine. The dynamic cables of the park devices are connected at the bottom to one or more power cables 41. The maintenance device 5 comprises one or more superstructures resting on the seabed F used for maintenance operations. With reference to FIGS. 3, 4 and 5A, the maintenance device 5 comprises a first so-called main platform 50a resting on the seabed F, and two secondary platforms 50b, 50c, resting on the seabed, arranged next to the first platform, and ii on which are mounted a lifting system 6. The two secondary platforms define between them a receiving zone 56, this reception zone being open on one side to receive a wind turbine device and closed on the other side by the main platform 50a. The lifting system comprises a rectangular immersed frame 61 placed between the two secondary platforms, connected by its lateral sides 61a to lifting means 60 arranged on the secondary platforms 50b, 50c. By way of example, the frame lifting means comprise a plurality of cables 62 connected to the lateral sides and hydraulic cylinder systems 63a, 63b mounted in the upper part of the secondary platforms 50b, 50c and acting on said cables to mount / go down the frame. Hydraulic cylinder systems are in particular of cable traction type, conventionally called "Strand jacks" hydraulic traction system. ls Cable bundles are attached to the frame and each bundle of cables is caught between jaws, said movable, mounted at the ends of rod (s) cylinder. For lifting, the cable bundle is clamped between the movable jaws, the movable jaws are moved upwards by the jacks, the cable bundle is caught between so-called fixed jaws, the movable jaws are loosened from the bundle of cables, lowered by the jacks, and tightened on the wire harness, then the fixed jaws are loosened. This cycle can be repeated as many times as necessary to raise the frame to the desired height. The frame 61 is defined so that a floating wind turbine device 25 is able to rest by its float on said frame. The lifting means make it possible to move the frame in a low position illustrated in FIG. 5A, in which a wind turbine device can be positioned between the two secondary platforms, above said frame, without contact with the latter, and a position 5B in which the wind turbine device is carried by the frame, said wind turbine device resting on the frame by the pontoons 22 and the float stabilization portions 211. In a variant, the frame lifting means comprise pulley cable systems connecting the frame to winch systems mounted in the upper part of the secondary platforms, hydraulic jacks acting directly on the frame, and / or 12

- rack and pinion systems and electric motors. As illustrated in Figure 4, the main platform can be connected to the secondary platforms by bridges 51, and the side 52 of the main platform disposed vis-à-vis secondary platforms s can be equipped with two elements 57 d support and guiding against which two columns of the float can come in support and slide during the rise / descent of the frame. The main platform supports maintenance tools, such as a crane 53, as well as a life base 54 for personnel responsible for the maintenance of the wind power generation system. Furthermore, the central platform may be equipped with an electrical substation 55, to which is connected the power cable or cables 41, including transformation means for transforming the electrical energy delivered by the power cable and the power cable. to bring to a higher voltage for its transport to the distribution network via a submarine cable 42. The method of performing maintenance operations according to the invention is as follows. In a first step, the dynamic cable 40 and the anchor lines 20 are disconnected from the wind turbine device. FIGS. 6A to 6D illustrate the step of disconnecting the dynamic cable by means of a first tug 9a. If necessary, the draft of the wind turbine device 1 is reduced by deballasting the float, in order to access the end 40a of the dynamic cable, above the level N of the sea, such as shown in Figure 6A. Preferably, the end 40a of the dynamic cable is always located above the level N of the sea. The end of the dynamic cable connected to the float is equipped with a socket or sock 81 to allow its connection to the end of the cable. a winch 91a of a first tug 9a as shown in FIG. 6B. The winch 91a of the tug takes the tension of the dynamic cable and the cable is disconnected from the float. The end 40a of the dynamic cable is brought back to the deck of the tug 9a, via its winch 91a, to allow the introduction of a buoy 82 on the dynamic cable, and the end of the dynamic cable equipped with the specific buoy. 82 is then released into the sea, as shown in Figures 6C and 6D. The buoy is specifically designed to maintain adequate dynamic cable tension. With reference to FIG. 7, the disconnection of the anchor lines is carried out by means of three tugs 9a, 9b and 9c, and a working barge 83 comprising three attachment points 83a, 83b, 83c for fixing the three anchor lines. A bushing is placed at the end of a first anchor line 3a to allow its connection to the cable end of a winch 91a of a first tug 9a. The tension of the anchor line 10 is taken up by the winch in order to disconnect the anchor line of the float. The end of the anchor line 3a is brought onto the tug deck via its winch 91a to connect it to the winch cable 831 of the barge. The end of the line is then disconnected from the winch cable of the tug, and returned to the barge deck via its winch 831 to be attached to said barge at a point of attachment 83a. During this operation, a second tug 9b keeps the barge 83 in position. The same operation is performed for the second anchor line 3b, and then for the third anchor line 3c. At least prior to the disconnection of the third anchor line 3c, the winch cable of the third tug 9c is connected to a tow line 84c which is attached to the third column 3c of the float. The third tug remains in the waiting position, its tow line is not tensioned, and is used to reposition the wind turbine device if necessary. The barge may further have an attachment point 832 for securing the end of the dynamic cable 40 or the aforementioned buoy 82 assembled at said end. Alternatively, the disconnection of the anchor lines may consist of raising the anchors and rewind the anchor lines by means of winches placed on the float. After disconnecting the anchor lines, the wind turbine device 1 is towed from the production site to the maintenance device. In order to facilitate this transfer, the device can be deballasted. Towing is performed by a tug, for example the third tug 9c. The first and second tugs 9a, 9b are connected by the tow lines 84a, 84b to the other two columns 21a, 21b to assist in the correct positioning of the device during the transfer, as shown in FIG. FIG. 9 illustrates the positioning of the wind turbine device above the frame in the lower position by means of the three tugs. The tow lines of the first tug 9a and the second tug 9b are detached from their respective winches, and the two tugs 9a, 9b come on either side of the third tug 9c to push the device 1 between the two sub-platforms 50b. , 50c. The float is brought into support by its two columns 21a, 21b against the two support and guide elements arranged on the side of the main platform, and is docked to the platform device. Guidance of the platform within the lifting area can also be assisted through the use of mooring lines. Each of the columns 21a, 21b bearing against the main platform is moored 1s by a first mooring line 85 to the main platform 50a and a second line 86 mooring to a secondary platform 50b, 50c. The third column 21c of the float is moored by a mooring line 87 to each of the secondary platforms. This mooring is achieved by means of winch systems arranged on the secondary platforms and / or the wind turbine device. Once the mooring is completed, the tow line 84c of the third tug 9c is removed. The wind turbine device can then be lifted by raising the immersed frame via the two systems 63a, 63b of synchronously controlled cylinders. Before lifting the immersed frame 61, the wind turbine device 25 can be re-ballasted in order to place it on the immersed frame in the low position, and to ensure that the positioning of the float on the immersed frame is correct. Special lifting points, reinforced, can be provided under the pontoons. The immersed frame is then raised by the lifting means. During the lifting operation, the float 30 is progressively deballasted. The frame is raised to a high position shown in Figure 5B to lift the wind turbine device to a position where the waves have no impact on the float, so that the wind turbine device is stable. and motionless for carrying out maintenance operations. Figure 3 illustrates the lifting system 35 being lifted, the frame 61 being between its low position and its high position.

Maintenance operations can then be performed on the wind turbine device, for example repairs or changes of blade, rotor, generator, mast, conversion means, and / or transformation means, columns or of float connection elements. The rotor is kept locked during all the disconnection, transfer and positioning operations on the maintenance device. FIGS. 10 and 11 illustrate a second embodiment in which the maintenance device 105 comprises a single platform 150 comprising in the upper part a rectangular reception zone 156, open on the outside, defined between two lateral portions 151a, 151b of the platform, for receiving a wind turbine device. The lifting system 106 comprises a submerged frame 161 installed between the two lateral portions 151a, 151b, and able to be lifted by lifting means 160 installed on the side portions, as previously described. The wind turbine device is supported by two columns against support members 157 and guide mounted on the platform in the receiving zone, opposite its open side.

The platform is equipped as before with a crane 153, a sub-station 155 and a station 154 for the staff. FIG. 12 illustrates a third embodiment in which the maintenance device 205 comprises a platform 250 comprising a reception zone 256 defined between two lateral portions 251a, 251b of the platform. The lifting system 206 is here formed of a ballastable box or buoy 261 slidably mounted at its lateral sides along vertical guide rails 264 mounted on said lateral portions. The buoy is ballasted, via a pump system 265 mounted on the platform, to be brought into the lower position illustrated in Figure 12. After positioning a device 1 of a wind turbine above said ballasted buoy, the buoy is unpacked. The deballasting of the buoy causes the rise of the buoy on which the wind turbine device rests. FIG. 13 illustrates another embodiment in which the maintenance device 305 comprises a platform 350 comprising a fixed immersed structure 359, on which a wind turbine device 16 is able to come to rest. The wind turbine device is deballasted so that its float is disposed above the level of the immersed structure 359, as illustrated by the device referenced 1b. The wind turbine device is then brought over the submerged structure 359, then the wind turbine device is ballasted, so that the wind turbine device rests on the submerged structure, supported by its pontoons and its components. stabilizing portions on the immersed structure, as illustrated by the device referenced 1c. The wind turbine device is ballasted so that the device rests stably on the immersed structure, this stability sufficient to counteract the impact of the waves on the float. According to another embodiment illustrated in FIGS. 14 and 15, the maintenance device 405 comprises a lifting system 406 comprising at least one retractable and liftable arm, for example two retractable and liftable arms 461a, 461b. The platform 450 comprises a receiving zone 456, for example of triangular or rectangular shape, defined between two lateral portions 451a, 451b of the platform, for receiving a wind turbine device 1. Each lateral portion is equipped with an arm 461a, 461b displaceable, for example by a translation displacement, between a low retracted position in which the arm is recessed with respect to said receiving zone, as illustrated in FIG. 14, and a low deployed position in which the arm protrudes into the receiving zone, as illustrated in FIG. 15. A wind turbine device is brought into the receiving zone, the arms 25 being in the retracted low position. . After docking the wind turbine device, each arm is operated in low deployed position to extend between the pontoon 22 connecting two columns 21a, 21c and 21b, 21c, and the beams extending from said columns. The arms in the deployed position are then maneuvered in a high deployed position, via appropriate lifting means, to lift the wind turbine device, each arm bearing preferably against the underside of two beams 23 of the float. During lifting, the float is gradually deballasted. Specific lifting points are advantageously provided under the beams.

Although the invention has been described in connection with various particular embodiments, it is obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if These are within the scope of the invention.

Claims (17)

REVENDICATIONS1. Method for carrying out maintenance operations on a floating wind turbine device belonging to a fleet of floating wind turbine devices, said floating wind turbine device (1) comprising a float (20), at least one wind turbine (10) ) mounted on said float, a system of anchor lines (3a, 3b, 3c) for anchoring the float at the bottom (F) underwater at a production site, and at least one electrical cable (40) for the connection of the wind turbine to an electrical distribution network Io, characterized in that it comprises a) the disconnection of said float (20) from the anchor line system (3a, 3b, 3c), and the cable (40 ) electric, (b) the towing of the floating wind turbine device (1) from its production site to a maintenance device (5, ls 105, 205, 305, 405), (c) the positioning of the wind turbine device on the maintenance device, so that the wind turbine device is supported by the hand device tenancy. 2. Method according to claim 1, characterized in that said maintenance device of steps b) and c) is fixed to the bottom (F) underwater. 3. Method according to claim 1 or 2, characterized in that the positioning step c) comprises a lifting operation of the wind turbine device (1) by means of a lifting system (6, 106, 206, 25). 406) of the maintenance device (5, 105, 205, 405). 4. Method according to claim 3, characterized in that step c) comprises the positioning of the wind turbine device (1) above a mobile immersed support (61, 161, 261), and the raising of said support immersed mobile to lift the wind turbine device. 30 5. Method according to claim 3, characterized in that the positioning step c) comprises - a deballasting of the float (20), - the positioning of the wind turbine device (1) above said immersed mobile support (61, 161, 261), 35 - the rise of said immersed mobile support with simultaneous deballasting of the float. 6. Method according to claim 1 or 2, characterized in that the positioning step c) comprises - a deballasting of the float (20), - the positioning of the device (1) wind turbine over a s support immersed (359) fixed, the maintenance device, - ballasting the float to put the wind turbine device on said immersed support. An offshore wind energy generating system for carrying out the method according to one of claims 1 to 6, comprising a fleet of offshore wind turbine devices (1), each wind turbine device comprising a float (20) and at least one wind turbine (10) mounted on said float, an anchor line system (3a, 3b, 3c), an electric cable (40) for connecting the wind turbine to a distribution network characterized in that it further comprises a maintenance device (5, 105, 205, 305, 405) provided with support means (61, 161, 261, 359, 461a, 461b) adapted to support at least a floating wind turbine device (1) disconnected from its anchor line system and electrical cable, said maintenance device being provided with maintenance means (53, 153) for performing maintenance operations on floating wind turbine. 8. System according to claim 7, characterized in that the maintenance device (5, 105, 205, 305, 405) is fixedly mounted on the bottom (F) underwater. 25 9. System according to claim 7 or 8, characterized in that said maintenance device (5, 105, 205) comprises at least one lifting system (6, 106, 206, 406) comprising a mobile immersed support (61, 161). , 261), constituting said support means, adapted to be moved by lifting means (60, 160, 265) between a low position 30 in which at least one wind turbine device is adapted to be disposed above said support immersed mobile, and a high position in which said wind turbine device is adapted to be carried by said movable immersed support. The system of claim 9, characterized in that said movable submerged support comprises a frame (61, 161), said hoisting means including cable systems (62) and / or hoist systems and / or systems (63a, 63b) of cylinders. 11. System according to claim 10, characterized in that said lifting means comprise jack systems type s cable traction cylinders. 12. System according to claim 9, characterized in that said mobile immersed support comprises a box (261) or ballastable buoy, said lifting means comprising a pump system (265) for ballast / déballaster said box. io 13. System according to one of claims 7 to 12, characterized in that the float (20) of the device (1) floating wind turbine is of the type serai-submersible. 14. System according to one of claims 7 to 13, characterized in that the float (20) of the wind turbine devices comprises a ls ballast system. 15. System according to claim 7, characterized in that the support means comprise a fixed immersed support (359) on which at least one wind turbine device (1) is suitable for landing by deballasting then ballasting said float. 20 16. System according to one of claims 7 to 15, characterized in that said maintenance device (5, 105, 205, 305) further comprises an electrical substation (55) to which the electric cables (40) of the Wind turbine devices (1) are connected, said substation including transforming means for transforming the electrical energy delivered by the wind turbines. 17. System according to one of claims 7 to 16, characterized in that it further comprises a barge (83) of work comprising at least one attachment point (83a, 83b, 83c) for fixing lines of anchoring (3a, 3b, 3c) of a wind turbine device (1).