Methods for launching, recovering, or inspecting floating offshore wind turbine structures.

Abstract

A method for launching, recovering, or inspecting a floating offshore wind turbine structure (1), which includes a wind turbine (2) and a support structure (3), after the structure has been assembled, is transported to a platform (16) at the top of an inclined slipway (23) extending from above the water surface (4) to a position below the water surface (4). The structure (1) is launched by lowering it from the platform (16) along the slipway (23) into the water until the assembled floating offshore wind turbine (1) is lifted away from the slipway (23) by the buoyancy of the floating support structure (3).

Description

Technical Field

[0001] The present invention relates to a method for assembling, launching, and possible recovery inspection, maintenance, repair, or disassembly of a wind turbine structure in the floating offshore area. Specifically, the present invention relates to a method as described in the preamble of the independent claims.

Background Art

[0002] A wind turbine in the floating offshore area is generally launched using one of the following methods: launching by a dry dock, launching by a semi-submersible barge, or launching by a slipway.

[0003] In the case of launching by a dry dock, the floating support structure is constructed in the dry dock and launched by flooding the dock. After launching, the floating support structure is towed to the quay area, where the wind turbine is subsequently installed using a land crane located adjacent to the quay area.

[0004] In the case of launching by a semi-submersible barge, the floating support structure is constructed on land, moved to one or more semi-submersible barges, and launched by submerging the barges. Here too, after launching, the floating support structure is towed to the quay area, where the wind turbine is subsequently installed using a land crane located adjacent to the quay area.

[0005] In the case of launching by a slipway, the floating support structure is constructed on land, moved to a skid, and launched by skidding on the slipway. An example is disclosed in International Publication No. WO 2016 / 138088 of the International Patent Application. After launching, the floating support structure is towed to the quay area, where the wind turbine is subsequently installed using a land crane located adjacent to the quay area. An example is disclosed in International Publication No. WO 2015 / 120227.

[0006] Single-column cylindrical floating structures are generally installed by other means due to the large draft of the floating support structure. Recent plans based on the concept of single-column cylindrical support structures are installed using large crane ships.

[0007] The description of "Port and Shipyard Requirements for the Installation of Floating Wind Turbines," published by Crowle and Thies of the University of Exeter in the RINA London branch in London, UK on October 21, 2021, outlines the above installation method.

[0008] In the Online CORE 2021 article, "Challenges during installation of floating wind turbines," by Crowle and Thies, presented at the 5th International Conference on Offshore Renewable Energy, 26-27 August 2021, the following installation methods are described. These are high-level procedures and vary somewhat depending on the type of foundation structure, the approach chosen by the developer, and the effectiveness of the installation vessel and port facilities. • Loading of floating foundation structures from the assembly yard. Generally, foundation structures are transported to the water by either flooding a dry dock, using a slipway, or using a heavy transport vessel. • A land crane (not in the case of a cylindrical buoy; see below) is used to install the turbine assembly onto the foundation structure. The cylindrical buoy is towed to the wind-reducing area and stabilized with ballast. Before the final move to the site, the turbine is installed on the foundation structure (using a crane ship). • Conduct final commissioning of the turbine and foundation structure system.

[0009] The installation method described above has several drawbacks.

[0010] Dry dock launching is severely limited by the dimensions of the available dry dock. Floating support structures for current wind turbine sizes typically have a width of 100 meters or more, and very few dry docks worldwide possess the necessary width. Such large dry docks tend to be frequently used for shipbuilding purposes.

[0011] Launching by semi-submersible barges is similarly constrained by the number of available semi-submersible barges of the required dimensions that can be obtained from the global market. This constraint is similar to the installation vessel constraint known for fixed-bottom offshore wind turbines, and potentially undermines one of the main advantages of floating offshore wind turbines over fixed-bottom offshore wind turbines, where large offshore installation vessels are not available.

[0012] Launching with a semi-submersible barge has a further disadvantage: moving the floating support structure to the semi-submersible barge depends on the sea surface conditions in the port where construction is taking place. Most ports are affected by tides and experience water level fluctuations throughout the day, and most ports are also affected to some extent by waves, in the form of large waves from the water outside the port entrance and / or by the wakes of passing ships. Changes in sea surface conditions often cause delays in the installation process, as the semi-submersible barge has to be displaced relative to the floating support structure being unloaded from its land position and wait for more favorable conditions.

[0013] All of the above-mentioned common installation methods have the disadvantage that, in the installation of wind turbines, the floating support structure is moored in the dock area, and then the wind turbine is installed using a land crane. The fact that most harbors are affected by tides, and that they are also affected to some extent by waves in the form of large waves from the water outside the harbor entrance and / or by the wakes of passing ships, displaces the floating support structure relative to the land crane. Such displacement, such as when launching the floating support structure using a semi-submersible barge, often results in delays in the installation process while waiting for a more favorable condition to develop.

[0014] For floating support structures that hold 2-3 MW class wind turbines, these challenges can sometimes be mitigated by installing the wind turbine on the floating support structure while it is in dry dock or on land, prior to barge launching. However, these challenges are not practical for modern wind turbines of 12-15 MW class or larger.

[0015] Other installation methods that attempt to overcome these challenges are described in the literature.

[0016] U.S. Patent Application Publication No. 2011 / 0119889 describes a method by which a floating support structure for a cylindrical buoy is gripped by a structure mounted on a crane vessel. This method ensures uniform and synchronized motion by the floating support structure and the crane, but incurs significant costs associated with a dedicated vessel operating at sea.

[0017] U.S. Patent Application Publication No. 2022 / 0316446 describes a method for launching a semi-submersible floating support structure from an extended deck carried by two ships. This method ensures uniform and synchronized motion by the floating support structure and crane, but incurs significant costs associated with dedicated ships operating at sea.

[0018] The above installation methods do not offer a readily available opportunity for a true "conveyor belt" installation of large, floating offshore wind power projects. The constraints of dry docks and semi-submersible barges limit the time of day that is convenient for installation, and when installing wind turbines in dock areas, daily changes in sea surface conditions further lead to halts and delays in the installation process.

[0019] Similar difficulties arise when floating support structures need to be lifted out of the water for inspection, maintenance, or repair. In this case, conventional methods suffer from all the aforementioned disadvantages and are costly and time-sensitive in order to enable the floating support structure to be returned to a land position.

[0020] For modern wind turbines of 12-15 MW class or larger, it is desirable to have a method for launching and recovering floating support structures that avoids the disadvantages of known methods. More specifically, it is desirable to have a method that enables a true "conveyor belt" type installation of large, floating offshore wind power projects. [Prior art documents] [Patent Documents]

[0021] [Patent Document 1] International Publication No. 2016 / 138088 [Patent Document 2] International Publication No. 2015 / 120227 [Patent Document 3] U.S. Patent Application Publication No. 2011 / 0119889 [Patent Document 4] U.S. Patent Application Publication No. 2022 / 0316446 [Non-patent literature]

[0022] [Non-Patent Document 1] "Port and Shipyard Requirements for the Installation of Floating Wind Turbines" published by Crowle and Thies of the University of Exeter at the RINA London branch in London, UK on October 21, 2021 [Non-Patent Document 2] Article in Online CORE 2021 of the 5th International Conference on Offshore Renewable Energy, August 26 - 27, 2021, by Crowle and Thies, "Challenges during installation of floating wind turbines" [Summary of the Invention] [Problems to be Solved by the Invention]

[0023] Therefore, an object of the present invention is to provide an improvement in the art. Specifically, it is an object to provide an improved launching method for floating wind turbines in offshore waters of 12 to 15 MW and above, where the support structure is launched into the water while the wind turbine is already attached to the support structure.

[0024] It is also an object to provide an improved recovery method for floating wind turbines in offshore waters of 12 to 15 MW and above, where the support structure is recovered to an onshore location for inspection, maintenance, repair, or disassembly while the wind turbine remains attached to the support structure. [Means for Solving the Problems]

[0025] These objects, and other advantages, are achieved using the methods and systems as described below and in the claims.

[0026] A floating offshore wind turbine structure comprises a wind turbine combined with a floating support structure. The floating support structure may be a semi-submersible or tension-moored support structure, or a cylindrical support structure using a separate barge. Regardless of the type of floating support structure, the floating offshore wind turbine structure is intended to float in the water surface.

[0027] For example, a wind turbine is supported on a semi-submersible floating support structure that includes a tower support for holding the wind turbine tower. This support structure comprises at least one buoyancy member, but typically multiple buoyancy members, to provide buoyancy to the support structure in the water. For example, the buoyancy members are positioned laterally with respect to the central axis of the tower, which is typically the vertical axis. Generally, each buoyancy member comprises one or more buoyancy columns fixed to the nodes of the support structure. Such buoyancy columns can generally be made of steel or reinforced concrete.

[0028] For example, an offshore location is in the sea, but it may also be offshore of a lake or other body of water. For simplicity, the following examples will focus on sea areas without explaining the general principles of use in other offshore bodies such as lakes.

[0029] The present invention is based on the use of a site comprising one or more combinations of the following elements: i) one or more land cranes, ii) one or more land stations for assembly, repair, and maintenance, and dismantling, iii) a land transport system, and iv) a slipway.

[0030] The land cranes may be local cranes available in the relevant port. These may be, for example, a Mammoet PTC200-DS or similar ring crane, or one or more crawler cranes, for example, a Liebherr LH11350 or similar. The cranes are fitted with boom extensions, allowing the turbine nacelle and blades to be mounted at hub height. Combinations of the above and other types of cranes are also possible.

[0031] Land stations for assembly, repair, and maintenance, as well as dismantling, may be specific locations suitable for crane operations and other related final work.

[0032] The assembly station is implemented adjacent to the fixed crane, facilitating standardized operations during assembly, repair, maintenance, and disassembly. One or more assembly stations can be implemented, suitable for crane operations using mobile cranes such as crawler cranes.

[0033] One or more stations may be constructed to complete a floating offshore wind turbine, including a floating support structure. This completion may include post-assembly internal completion of the wind turbine, such as cable connections and final bolt tightening, installation of accessories such as navigation lights, energy supply and commissioning, and even test operation under specific operating conditions, leaving sufficient margin of stability while upright offshore.

[0034] One or more stations may be implemented to use smaller cranes for inspection, maintenance, or repair of floating support structures or wind turbines. These smaller cranes cannot lift major components of the structure such as the entire rotor, nacelle, or tower, but they can lift related major components such as the blades, gears, and generators.

[0035] One or more stations may be provided for the dry storage of completed floating offshore wind turbines awaiting launch, or for floating offshore wind turbines that have been recovered and are awaiting inspection, maintenance, or repair, or for floating offshore wind turbines that have reached the end of their service life and are awaiting dismantling.

[0036] Land transport systems can be implemented based on lateral sliding. The lateral sliding track can be permanently installed or removable. The movement of components of a floating support structure, and the completed floating support structure with the wind turbine attached, can be carried out by sliding the components or structure on the lateral sliding track. Alternatively, it can be carried out using wheelbase trolleys or friction reduction devices. Alternative transport systems can be implemented based on SPMTs (Self-Propelled Modular Transporters), rollers, or other systems that do not rely on tracks but on rolling or sliding on large flat or inclined surfaces.

[0037] Certain advantages can be realized by using a lateral slip track arrangement suitable for a given type of floating support structure. For example, a triangular semi-submersible floating support structure can be advantageously transported using two lateral slip tracks. Thus, three lateral slip tracks are used, one track supporting two of the three legs at the vertices of the triangular structure, or each track supporting one of the three legs at the vertices of the triangular structure.

[0038] A slipway forming an inclined surface can be constructed to connect one or more wide, flat, horizontal areas to the sea or any other relevant body of water, for use in the assembly, completion, inspection, maintenance, repair, or dismantling of floating offshore wind turbines. The slipway may be made of concrete or steel and may be fitted with skids to facilitate the launching process.

[0039] Certain advantages are realized by using a slipway configuration with three parallel tracks. In this configuration, each of the three legs at the vertices of the triangular structure is supported by a corresponding track during launch, for example, a corresponding trolley, and is lowered into the water along these tracks until the support structure floats away from the tracks due to the lifting of buoyancy members.

[0040] Another specific advantage is achieved by using a slipway configuration with three parallel tracks, where the central track is offset away from the dock area relative to the two lateral tracks, and each of the three legs at the vertices of the triangular structure is supported by the corresponding track during launch. Such an offset causes the floating offshore wind turbine to tilt less sharply than the inclination of each track as it descends the slipway and launches. This improves the stability of the floating offshore wind turbine during launch.

[0041] Another specific advantage is achieved by using a central orbit offset equal to the distance of the line connecting the centers of the two legs moving along the lateral orbits and the center of the third leg moving along the central orbit. This specific offset ensures that the floating offshore wind turbine maintains its vertical position as it descends from the slipway and launches. This further enhances the stability of the floating offshore wind turbine during launch.

[0042] In this way, the support structure is moved from the platform onto three tracks while advantageously holding the wind turbine, so that the first, second, and third legs are simultaneously supported by the first, second, and third tracks, respectively. The support structure is lowered into the water along the three parallel tracks until the support structure floats away from the tracks due to the lifting of the buoyancy members. For the support structure to float away from the tracks, the tracks extend underwater to a depth D1. Depth D1 is a sufficient depth below the water surface to maintain the orientation of the support structure until it floats away from the tracks. In particular, as a semi-submersible, floating support structure, the support structure extends to a depth D2 below the water surface when it floats away from the tracks. D2 is less than the depth D1.

[0043] The improved installation and launching method for floating offshore wind turbines of 12-15 MW class or larger, according to the present invention, comprises several steps.

[0044] Firstly, preparations are made to install a wind turbine on a floating support structure.

[0045] Floating structures can be assembled on the designated site or elsewhere.

[0046] An advantageous assembly layout on the designated site can be achieved by assembling prefabricated modules at the assembly station.

[0047] If assembled at a different location, the floating support structure can be transported to the installation site using a land transport system. Alternatively, it can be transported to the installation site by sea and the slipway can be laterally hoisted onto the transport system, or lifted onto the transport system using one or more cranes.

[0048] Secondly, once the floating support structure is ready for turbine installation, it is placed in a turbine assembly station. The turbine assembly station may be the same station where the floating support structure assembled at the designated site is assembled from prefabricated modules, or it may be a different assembly station.

[0049] Next, the wind turbine is installed on a floating support structure using one or more cranes.

[0050] Certain advantages can be realized by stabilizing the floating support structure with ballast before the wind turbine is installed. This pre-ballast improves the onshore stability of the floating offshore wind turbine structure, which includes the floating support structure and wind turbine, and eliminates the need for ballast stabilization after the launch of the floating offshore wind turbine.

[0051] Next, the floating offshore wind turbine structure, equipped with a floating support structure and wind turbine, is completed. This completion may include the internal completion of the wind turbine after assembly, such as cable connections and final bolt tightening, installation of accessories such as navigation lights, energy supply and commissioning, and even test operation under specific operating conditions, leaving sufficient margin for stability while upright on land. This completion may be carried out at a turbine assembly station or at one or more different stations.

[0052] If ballast stabilization is not carried out before the installation of the wind turbine, certain advantages can be realized by stabilizing the floating support structure with ballast before any test work. This pre-ballast improves the onshore stability of the floating offshore wind turbine, which includes the floating support structure and wind turbine, and eliminates the need for ballast stabilization work after the launch of the floating offshore wind turbine.

[0053] Next, if the slipway positioning has not yet been determined, the floating offshore wind turbine structure is transported to the slipway. Prior to transport to the slipway, the floating offshore wind turbine structure may be temporarily stored at an onshore storage station.

[0054] Next, the floating offshore wind turbine structure is launched using a slipway. The movement down the slipway continues until the floating offshore wind turbine structure floats away from the slipway, either by leaving the slipway itself, leaving the skid of the slipway, or leaving the support members used to support the floating support structure on the slipway or skid.

[0055] A specific advantage can be achieved by providing a pivoting support member to a floating offshore wind turbine structure, which allows movement from the horizontal plane to the inclined surface of the slipway without applying end loads to the underside of the floating support structure.

[0056] A specific advantage can be realized by providing additional blast to the floating offshore wind turbine structure before launching it using a slipway, thereby ensuring stability even on the inclined surface of the slipway.

[0057] After launching, the floating offshore wind turbine structure may be moored in a harbor for final completion while a laying ship or similar vessel is available, or it may be towed directly from the slipway to the offshore laying site.

[0058] In a similar manner, the improved recovery method for floating offshore wind turbine structures of 12-15 MW class or larger according to the present invention comprises several steps.

[0059] Firstly, the floating offshore wind turbine structure is towed to a slipway. There, it is moved onto support members that facilitate the use of a transport system at the site. The support members can be pivoted to allow movement from the inclined surface of the slipway to the horizontal surface of the site.

[0060] Floating offshore wind turbines can have their ballast partially or completely removed before being transported up a slipway.

[0061] Next, the floating offshore wind turbine structure is transported up a slipway to the horizontal plane of the designated site.

[0062] Next, the floating offshore wind turbine structure is transported to one or more stations for inspection, maintenance, repair, or dismantling of the floating support structure or the wind turbine. The stations may be located adjacent to the slipway.

[0063] After inspection, maintenance, or repair work is completed, floating offshore wind turbines can be relaunched using a slipway.

[0064] The present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawing]

[0065] [Figure 1] This is a three-dimensional perspective view of a floating offshore wind turbine. [Figure 2] This is a side view of a semi-submersible wind turbine floating offshore. [Figure 3] This figure shows an alternative, semi-submersible offshore wind turbine. [Figure 4] This figure shows another alternative example of a semi-submersible offshore wind turbine. [Figure 5A] This is a perspective view of the site. [Figure 5B] This is a perspective view of the site. [Figure 5C] This is a perspective view of the site. [Figure 5D] This is a perspective view of the site. [Figure 6] A perspective view of the slipway extending from the platform into the water. [Figure 7] This is a front view of the slipway extending from the platform into the water. [Figure 8] This is a side view of the launching station. [Modes for carrying out the invention]

[0066] Figure 1 shows a floating offshore wind turbine structure 1. The floating offshore wind turbine structure 1 comprises a wind turbine 2 and a floating offshore support structure 3 with a tower support 8 to which the wind turbine 2 is mounted for operation and supported under offshore conditions. The wind turbine 2 comprises a rotor 5, a tower 7, and a nacelle 6 connecting the rotor 5 to the tower 7.

[0067] The offshore support structure 3 is a semi-submersible, floating offshore structure with buoyancy members 9A, 9B, and 9C. The buoyancy members 9A, 9B, and 9C assist in keeping the support structure 3 partially above the water surface, providing stability to the semi-submersible, floating structure. An example of the water surface 4 relative to the vertical extension direction D2 of the buoyancy members 9A, 9B, and 9C below the water surface 4 is shown in Figure 2. It can be seen that the buoyancy members 9A, 9B, and 9C are half submerged in the water. When floating, the support structure extends below the water surface 4 by a structure depth D2.

[0068] The semi-submersible support structure is typically used with mooring lines (not shown) anchored to the seabed to maintain the support structure 3 in place. In the floating support structure 3, to vertically attenuate the effects of waves, heave plates 14 extend horizontally from the bottom of the buoyancy members 9A, 9B, and 9C. Each of the buoyancy members 9A, 9B, and 9C, including the heave plates 14, functions as a leg 13 on land or other horizontal construction platform.

[0069] The exemplary structure 3 has a tetrahedron shape and comprises a first radial brace 11A extending from the lower part of the tower support 8 to the first buoyancy member 9A at the most distal node, and two other radial braces 11B, 11C. The radial braces 11B, 11C extend from the lower part of the tower support 8 to each of the other remaining two buoyancy members 9B, 9C at the nodes opposite the tower support 8. Further stability is achieved by two additional braces 10A. They extend from the most distal buoyancy member 9A to the two other buoyancy members 9B, 9C. The two additional lateral braces 10A, together with the two short radial braces 11B, 11C, form a flat triangular shape. As illustrated in Figure 2, the buoyancy members 9A, 9B, 9C are located at three nodes in the tetrahedron.

[0070] The term radial brace is used for braces 11A, 11B, and 11C, which extend radially away from the tower support 8. The term oblique brace is used for braces 12A, 12B, and 12C, which are the hypotenuses in the perpendicular triangle formed by the tower support 8, one of the radial braces 11A, 11B, or 11C, and one of the oblique braces 12A, 12B, or 12C.

[0071] The tower support section 8 is exemplified as a cylindrical support column with a central axis 15, which is also the central axis of the tower 7. However, the tower support section 8 can have other shapes. As shown in Figure 2, the tower support section 8 extends to a position above the water surface 4, which is characteristic of a semi-submersible floating support structure.

[0072] As shown in Figures 1 and 2, in the arrangement of triangles, the corners of the tetrahedron are arranged according to elongated isosceles triangles having a width B at the base and a height A from the base to the vertex.

[0073] However, by choice, the triangle is an equilateral triangle.

[0074] As shown in Figure 1, the tower support 8 is located in the middle of the base of the triangle. In other embodiments, the tower support 8 is located in the center of a triangle, for example, an equilateral triangle.

[0075] Figure 3 shows an alternative structure in which the tower support is centrally located between buoyancy members, each having a pair of buoyancy columns. The pairs of buoyancy columns are positioned at the corners of an equilateral triangle.

[0076] Figure 4 shows another example, where the tower is positioned at the center of a triangle and the support structure is not a tetrahedron, but the tower support is connected to the buoyancy member by a horizontal bottom bar. This horizontal bottom bar serves as a seawater tank for permanent ballast.

[0077] These are illustrative examples, and other examples of triangular and tower support positions are possible.

[0078] Figure 5A is an example of a perspective view of the site 100. The site 100 has several stations, namely an assembly station 200, a completion station 300, a storage section 400, and a launching station 500. As can be seen in Figure 5A, the floating offshore wind turbine structure 600 has been launched and is in the process of being towed to the installation site.

[0079] As shown in more detail in Figure 5B, the ring crane 201 is positioned at assembly station 200. Assembly station 200 is connected to two assembly stations 203 and 204 of the floating support structure via skid tracks 202. Floating support structure 3 is in a partial stage of assembly, using a smaller crane (not shown). The wind turbine 2 is mounted on top of floating support structure 3 by the ring crane 201.

[0080] The ring crane 201 may be advantageously positioned adjacent to the dock area so that it can be used to unload goods brought in from ships and barges.

[0081] As shown in Figure 5B, the floating offshore wind turbine structure 1 is located at the completion station 300. The floating offshore wind turbine structure 1 is transported to the completion station 300 using a skid track 302. Medium-voltage cables are connected to the floating offshore wind turbine structure 1, enabling not only structural completion (final tightening of bolts, installation of cables, installation of final equipment, etc.) but also electrical completion (verification of all electrical connections) and test operation.

[0082] As can be seen more clearly in Figure 5C, several floating support structures 3 and several floating offshore wind turbine structures 1 are located at the storage station 400. They are moved to the storage station 400 on a sideslip track 405.

[0083] As shown in Figure 5D, the floating offshore wind turbine structure 1 is located at the launching station 500, which comprises a horizontal or nearly horizontal platform 16 and a slipway 23. The second floating offshore wind turbine structure 1 is in the process of being launched by descending the slipway 503.

[0084] Figures 6 and 7 show the wind turbine equipment 1 positioned at the end of the slipway 23, which is shown as a ramp on platform 16. The slipway 23 is constructed with offsets from tracks 17A, 17B, and 18. Generally, the support structure 3 is pushed to the slipway 23 on a trolley 21 or lifted to this position by a crane.

[0085] The slipway 23 comprises a first track 17A, a second track 17B, and a third track 18, which extend parallel to each other from the platform 16 into the water surface 4. The first track 17A and the second track 17B are arranged symmetrically on either side of the third track 18, which is the central track. The first track 17A and the second track 17B are offset horizontally from the third track 18 by a distance equal to the height A of the triangle, as shown in more detail in Figure 7.

[0086] As shown in Figure 8, the floating offshore wind turbine structure 1 moves along three tracks 17A, 17B, 18 until the support structure 3, which includes the wind turbine 2, floats away from the tracks 17A, 17B, 18 due to the lifting of buoyancy members 9A, 9B, 9C, which are shown in more detail in Figure 1. The tracks 17A, 17B, 18 extend underwater to a depth D1 below the water surface 4. The depth D1 is sufficient underwater depth to maintain the orientation of the support structure 3 until the wind turbine equipment floats away from the tracks 17A, 17B, 18 due to the lifting of buoyancy members 9A, 9B, 9C. As described above, when it begins to float, the support structure 3 extends to a depth D2 below the water surface 4, which is less than the depth D1 to which the ends of the tracks 17A, 17B, 18 extend underwater. This will be explained in more detail in Figure 7, but it shows a situation where the wind turbine equipment 1 has begun to float and is no longer supported by tracks 17A, 17B, and 18.

[0087] To facilitate movement along tracks 17A, 17B, and 18, indicated by the double-headed arrows 22, each leg 13 of the support structure 3 is carried by a wedge-shaped trolley 21. A trolley 21 is provided for each track 17A, 17B, and 18, and is generally accompanied by rollers on its underside. Optionally, the trolley has brakes to control the speed of launching. This allows for the use of relatively steep slipways / ramps 23, which are useful for narrow bodies of water at the ends of slipways / ramps 23, such as harbors, rivers, or canals.

[0088] Optionally, rails may be provided on at least one, but preferably at least two, of the tracks 17A, 17B, and 18 for better guidance of the bogie during launching.

[0089] The general dimensional range for the system outlined above for 12-15 MW class turbines is as follows: The designated site 100 may have an extension of approximately 300m or more in a direction parallel to the pier area, and a width of approximately 500m in a direction perpendicular to the pier area. The wind turbine 2 may have a rotor diameter of 220 m or more, and a distance of 115 m or more from the bottom flange of the tower to the rotor center. The floating support structure 3 may have an extension of 100m and a width of 100m. Slipway 503 may have a width of approximately 120m or more and a slope of 3-10°. Tracks 17A, 17B, and 18 may have a width of 15m or more and an inclination of 3 to 30°.

Claims

1. A method for launching a floating offshore wind turbine structure (1), The steps include constructing a floating offshore wind turbine structure (1) by setting the wind turbine (2) on a floating support structure (3) at an onshore assembly station (200) using one or more onshore cranes (201), The floating offshore wind turbine structure (1), including the wind turbine (2) and the support structure (3), is transported to a platform (16) at the top of an inclined slipway (23) that extends from above the water surface (4) down to the water body. The floating offshore wind turbine structure (1) is launched by lowering it from the platform along the slipway (23) into the water until it is lifted away from the slipway (23) by the buoyancy of the floating support structure (3), Methods that include...

2. The method according to claim 1, further comprising the step of completing the floating offshore wind turbine structure (1) at a completion station (300) located away from the assembly station (200).

3. The method according to claim 2, further comprising the step of performing inspection work on the floating offshore wind turbine structure (1) at the completed station (300).

4. The method according to any one of claims 1 to 3, comprising the step of providing a fillable water ballast tank on the support structure (3) to adjust the buoyancy of the support structure (3) when the support structure (3) is submerged in water, and further comprising the step of partially or completely stabilizing the floating support structure (3) with water ballast during construction prior to launching.

5. The floating support structure (3) is provided with first, second, and third legs (13) positioned at each corner of the triangle. A step of providing first, second, and third tracks (17A, 17B, 18) extending into the water from the platform (16) parallel to each other, wherein the first and second tracks (17A, 17B) are arranged symmetrically on both sides of the third track (18) and are offset horizontally by a certain distance from the third track (18) toward the water into which the assembled floating offshore wind turbine (1) is launched. The step of moving the support structure (13) from the platform (16) onto the three tracks (17A, 17B, 18) such that the first, second, and third legs (13) are simultaneously supported by the first, second, and third tracks (17A, 17B, 18), The support structure (3) is lowered and moved in the water along the three tracks (17A, 17B, 18) and parallel to the tracks (17A, 17B, 18) until the support structure (3) floats away from the tracks (17A, 17B, 18) extending in the water due to the buoyancy of the buoyancy members (9A, 9B, 9C). The method according to any one of claims 1 to 4, including

6. The method according to claim 5, comprising the step of providing the first, second, and third tracks (17A, 17B, 18) parallel to each other in the direction from the platform (16) toward the water, wherein the first and second tracks (17A, 17B) are arranged symmetrically on both sides of the third track (18) and offset horizontally by a distance D from the third track (18), where D is equal to the distance of the line connecting the centers of the two legs moving on the first and second tracks (17A, 17B) and the third leg (18) moving on the third track (18).

7. The method according to any one of claims 1 to 6, wherein the leg portion (13) is formed by buoyancy members (9A, 9B, 9C), and the method includes the step of positioning the buoyancy members (9A, 9B, 9C) on a track (17A, 17B, 18) while the vessel is being launched.

8. The method according to any one of claims 1 to 7, comprising the step of positioning each of the legs (13) on three trolleys (21) on the tracks (17A, 17B, 18), wherein each trolley (21) is wedge-shaped to maintain the upper surface of the trolley (21) horizontally on the inclined surface of the corresponding tracks (17A, 17B, 18), and each trolley (21) has rollers on its underside to rest on the tracks (17A, 17B, 18) so as to roll on the tracks (17A, 17B, 18) while the support structure is being launched.

9. A method for recovering a floating offshore wind turbine (1) from a body of water, the method comprising the step of recovering the floating offshore wind turbine (1), which comprises a wind turbine (2) and a support structure (3), by sliding and raising a slipway (23) until the floating offshore wind turbine (1) is positioned on a horizontal platform (16) in a launching area (500).

10. The method according to claim 9, comprising the step of performing the reverse of the assembly method described in any one of claims 5 to 8.

11. A method for inspecting, maintaining, repairing, or dismantling a floating offshore wind turbine structure (1) after recovery according to claim 9 or 10, the method comprising the step of inspecting, maintaining, repairing, or dismantling the floating offshore wind turbine structure (1) at a location different from its position on the horizontal platform (16) in the launching area (500) where the floating offshore wind turbine (1) is located, immediately after the completion of the recovery operation.

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