Substructure for floating offshore wind power generation, construction method for the substructure for floating offshore wind power generation, and installation method for offshore wind power generation equipment.

Abstract

To provide an understructure for floating type offshore wind power generation, etc., applicable for upsizing and capable of suppressing thickening of plate thickness.SOLUTION: An understructure for floating type offshore wind power generation 1 is a basic structure for supporting a wind power generation device 3 in a state of being floated on the ocean. The understructure for floating type offshore wind power generation 1 has a wind power generation device 3 arranged above an upper floor slab 5 of the understructure for floating type offshore wind power generation 1 in a state of floating on the ocean to have the longitudinal direction face the vertical direction. The understructure for floating type offshore wind power generation 1 is mainly composed of a cylindrical structure 7, the upper floor slab 5, and a lower floor slab 9, etc.. The lower floor slab 9 is joined to lower ends of the plurality of cylindrical structures 7, and the upper floor slab 5 is joined above. That is, a plurality of cylindrical structures 7 are fixed by the upper floor slab 5 and the floor slab 9 and a sealed space is formed inside the cylindrical structure 7. In addition, the wind power generation device 3 is attached to the upper floor slab 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a substructure for floating offshore wind power that supports an offshore wind power generator, and the like.

Background Art

[0002] As an offshore structure such as an offshore wind power turbine, a floating type method of supporting a tower or the like has been proposed. Generally, compared to a bottom-mounted substructure, such a floating substructure is applied at a water depth of, for example, 50 m or more in consideration of cost and the like. In addition, as floating substructures, so-called barge type, semi-submersible type, spar type, etc. have been proposed depending on the water depth and the like.

[0003] Here, the spar type, which has the simplest shape, is mostly located underwater, is more resistant to shaking compared to the barge type and the like, and is said to be lower in manufacturing cost. On the other hand, a spar-type floating body, depending on the scale of the wind turbine, is said to require at least a water depth of 100 m or more.

[0004] Here, as a floating substructure, a steel floating body is generally used. However, steel floating bodies deteriorate due to rust and the like over time, so regular inspection and repair are required. During 20 to 30 years of use, inspection and repair work in docks similar to those for ships and the like are required. For this reason, methods using a concrete floating body have also been proposed (for example, Patent Documents 1 to 2).

Prior Art Literature

Patent Literature

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, there has been a growing interest in increasing the size of wind turbines to achieve cost advantages in terms of wind absorption efficiency, power generation efficiency, and maintenance efficiency. This necessitates increasing the size of the floating structure itself. For example, if the floating structure is made of steel, the thickness of the cylindrical steel plates must also be increased. However, bending thick steel plates presents challenges. This is because, compared to Europe, which has a long history of manufacturing thick, large-diameter piles for large wind turbines, Japanese factories lack the necessary processing equipment and manufacturing management expertise for bending thick steel plates.

[0007] Furthermore, for example, large spar-type floating structures made of concrete present numerous manufacturing challenges, such as the need to assemble reinforcing bars and formwork and pour concrete while the large-section cylindrical concrete structure is lying horizontally. Even when using concrete, the wall thickness of the cylinder can become excessively thick, raising concerns about temperature cracking during manufacturing.

[0008] This invention has been made in view of the aforementioned problems, and aims to provide a substructure for floating offshore wind power generation that can be applied to larger scales and minimize the need to increase the thickness of the plates. [Means for solving the problem]

[0009] To achieve the aforementioned objective, the first invention provides a substructure for a floating offshore wind power generation system, comprising: an upper deck to which a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are constructed by connecting a plurality of ring members in the longitudinal direction. The cylindrical structure is made of prestressed concrete, and at least a portion of the joint surfaces between the ring members is made of steel. This is a floating offshore wind power generation substructure characterized by the following features.

[0010] The second invention is a substructure for a floating offshore wind power generation system, comprising: an upper deck to which a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are formed by connecting a plurality of ring members in the longitudinal direction, and gaps are formed between the plurality of cylindrical structures through which waves can pass, and the gaps are smaller than the outer diameter of the cylindrical structures. The floating body is of the spar type, and its total length is five times or more the outer diameter of the circumscribed circle of the multiple cylindrical structures. This is a floating offshore wind power generation substructure characterized by the following features. The third invention is a substructure for a floating offshore wind power generation system, comprising: an upper deck to which a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are composed of a plurality of ring members connected in the longitudinal direction, the size of the lower deck is larger than the size of the upper deck, and the lower deck extends outward from the outermost part of the cylindrical structures. The floating body is of the spar type, and its total length is five times or more the outer diameter of the circumscribed circle of the multiple cylindrical structures. This is a floating offshore wind power generation substructure characterized by the following features.

[0011] It is desirable that partition walls be provided inside the cylindrical structure to divide the space.

[0012] The cylindrical structure may be made of prestressed concrete. In this case, at least a portion of the joint surfaces between the ring members may be made of steel.

[0013] The cylindrical structure may be made of steel.

[0015] Multiple of the aforementioned cylindrical structures may be further joined together by an intermediate floor slab between the upper floor slab and the lower floor slab.

[0016] 1 -3According to this invention, compared to a single-cylinder spar-type floating structure, the cylindrical structure is divided into multiple sections, resulting in a smaller diameter for each section. This allows for the construction of larger wind turbines without increasing the plate thickness. Furthermore, since the cylindrical structure is constructed by connecting multiple ring members in the longitudinal direction, it can be constructed to the desired length simply by changing the number of connections. In the case of concrete construction, this means that not only will the formwork for each ring be the same size (diameter, height, thickness), but it may also be possible to adjust the number of cylinders of the same size according to design conditions such as the size of the wind turbine. This results in formwork of the same dimensions and allows for reuse, leading to cost reductions.

[0017] Furthermore, by creating gaps between multiple cylindrical structures, waves can pass through these gaps. This allows for the suppression of the effects of wave forces.

[0018] Furthermore, by installing partition walls inside the cylindrical structure to divide the space, it can be used as a ballast storage room, making it easier to control the floating body's posture, such as raising its vertical position and adjusting its draft.

[0019] Furthermore, if the floating structure is made of prestressed concrete, it does not have the problems of rust and other issues that steel structures do. Also, unlike steel floating structures, it does not require welding or other work at a specialized shipyard, so it can be assembled in a coastal area close to the installation site. For this reason, the assembly and transportation of the substructure for floating offshore wind power generation is easier.

[0020] Even in this case, if at least a portion of the joining surfaces between the ring members are made of steel, the flatness of the joining surfaces can be increased, ensuring high watertightness. Furthermore, if necessary, welding the outer surface can ensure even higher watertightness.

[0021] Furthermore, even when the cylindrical structure is made of steel, it is possible to avoid excessively large diameters or thick walls, making manufacturing easier.

[0022] Furthermore, by making the overhang length of the lower floor slab larger than that of the upper floor slab, vertical movement (heave) and the like of the substructure can be suppressed, and a part of the lower floor slab can function as a swing suppression function.

[0023] Furthermore, the cylindrical structures can be reinforced by joining the plurality of cylindrical structures not only at the upper end and the lower end but also between the upper floor slab and the lower floor slab by an intermediate floor slab. Additionally, a structure formed by joining the upper ends and lower ends of the plurality of cylindrical structures with the upper floor slab and the lower floor slab can be further increased in size by connecting them in the longitudinal direction. In this case, it is only necessary to join the upper floor slab of the previously manufactured substructure for floating offshore wind power generation and the lower floor slab of the subsequently manufactured substructure for floating offshore wind power generation, and this joined portion can function as an intermediate floor slab.

[0024] The 4 invention relates to a construction method for a substructure for floating offshore wind power generation according to the first -3 invention, characterized by comprising: a step of holding the lower floor slab in an upright state, arranging and joining a plurality of ring members to the sides of the lower floor slab; a step of sequentially arranging other ring members on the sides of existing ring members, moving the other ring members toward the existing ring members and connecting them to form the plurality of cylindrical structures each having a predetermined length; and a step of arranging the upper floor slab at ends of the plurality of cylindrical structures and joining the upper floor slab to the cylindrical structures.

[0025] In order to maintain the spacing between the cylindrical structures, at least some of the cylindrical structures may be arranged on an upper portion of a support to maintain the spacing with other cylindrical structures.

[0026] According to the 4 invention, since the cylindrical structure is constructed by connecting ring members in the horizontal direction, manufacturing is easy even for a long substructure.

[0027] In this case, in order to maintain the spacing between the cylindrical structures, at least some of the cylindrical structures are placed on top of the support, and by maintaining the spacing between them and other cylindrical structures, gaps can be formed between the cylindrical structures through which waves can pass.

[0028] The 5 The invention The floating offshore wind power generation substructure comprises an upper deck to which wind power generation equipment is attached, a plurality of hollow cylindrical structures joined below the upper deck, and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are formed by connecting a plurality of ring members in the longitudinal direction, and the plurality of cylindrical structures are further joined to each other by an intermediate deck between the upper deck and the lower deck. A method for constructing a substructure for a floating offshore wind power generation system, comprising: step a, on land, arranging a plurality of ring members on the lower deck to form a plurality of cylindrical structures of a predetermined length; step b, arranging the upper deck at the ends of the plurality of cylindrical structures and joining them to the cylindrical structures to form a substructure for a floating offshore wind power generation system; step c, fixing the substructure for a floating offshore wind power generation system to a float and towing the float to a deeper location; step d, lowering the substructure for a floating offshore wind power generation system to the bottom so that its upper part is above the water surface; and step e, joining another substructure for a floating offshore wind power generation system to the upper part of the floating offshore wind power generation system, wherein steps c to e are repeated.

[0029] The 5 According to this invention, the substructure for a floating offshore wind power generation system can be enlarged by first manufacturing the substructure for the floating offshore wind power generation system, then lowering it to the bottom so that its upper part is above the water surface, and then joining the substructure for a floating offshore wind power generation system that is manufactured later to the upper part of the first manufactured substructure for the floating offshore wind power generation system. Therefore, even large substructures for floating offshore wind power generation systems can be easily manufactured. In this case, since the substructures for floating offshore wind power generation systems are joined together while the first manufactured substructure is lowered to the bottom, the effects of waves and currents can be suppressed.

[0030] The 6 The invention is, The substructure for a floating offshore wind power generation system comprises an upper deck to which wind power generation equipment is attached, a plurality of hollow cylindrical structures joined to the lower part of the upper deck, and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are constructed by connecting a plurality of ring members in the longitudinal direction.A method for installing an offshore wind power generation device using a floating offshore wind power generation substructure, comprising the steps of: installing a temporary frame on the seabed of a quay; fixing a base plate to the upper part of the temporary frame; installing a wind power generation device on the upper part of the base plate; arranging submerged floats around the temporary frame and raising them to the surface, fixing the base plate and the floats together, and releasing the fixing of the base plate and the temporary frame; raising the floats to the surface, detaching the wind power generation device from the temporary frame, and towing it to the installation site. The method for installing an offshore wind power generation device is characterized by comprising the steps of: sailing; towing the floating offshore wind power generation substructure to the installation site in a horizontal position and erecting it by introducing ballast; aligning the base plate with the upper deck plate of the floating offshore wind power generation substructure by sinking or raising at least one of the float or the floating offshore wind power generation substructure; and joining the base plate and the upper deck plate and retracting the float.

[0031] The 6 According to this invention, the wind power generation device can be assembled on a temporary frame, moved to the installation site using floats, and fixed to the upper part of the floating offshore wind power generation substructure at sea, thereby enabling the installation of the offshore wind power generation device at sea. [Effects of the Invention]

[0032] According to the present invention, it is possible to provide a substructure for floating offshore wind power generation that can be applied to larger sizes and minimize the need for increasing the diameter and thickness of the plates. [Brief explanation of the drawing]

[0033] [Figure 1] A diagram showing the usage status of the substructure 1 for a floating offshore wind power generation system. [Figure 2] (a) and (b) are front views showing the substructure 1 for a floating offshore wind power generation system, and (c) is a cross-sectional view of (a) along line AA. [Figure 3] A diagram showing the manufacturing method of the lower floor slab 9. [Figure 4](a) is a diagram showing the manufacturing method of the substructure 1 for floating offshore wind power generation, and (b) is a cross-sectional view of (a) along line EE. [Figure 5] (a) to (e) are diagrams showing the structure of the joint between the ring members 19. [Figure 6] (a) to (c) are diagrams showing the installation method of the substructure 1 for floating offshore wind power generation. [Figure 7] (a) is a diagram showing the construction method of wind power generation device 3, and (b) is a view of (a) from arrow G. [Figure 8] (a) is a diagram showing how to move the wind power generation device 3, and (b) is a view of (a) from the perspective of arrow G. [Figure 9] (a) and (b) are diagrams showing how to move a wind power generation device. [Figure 10] (a) to (d) are diagrams showing how to install the wind power generation device 3 on the floating offshore wind power generation substructure 1. [Figure 11] (a) and (b) are diagrams showing other manufacturing methods for the floating offshore wind power generation substructure 1. [Figure 12] (a) and (b) are diagrams showing the method of moving the substructure 1 for floating offshore wind power generation. [Figure 13] (a) to (c) are diagrams showing other manufacturing methods for the floating offshore wind power generation substructure 1. [Figure 14] (a) is a diagram showing another embodiment of the substructure 1 for floating offshore wind power generation, (b) is a line II cross-sectional view of (a), and (c) is a diagram showing another embodiment of (b). [Figure 15] A diagram showing other laying structures for the substructure 1 of a floating offshore wind power generation system. [Modes for carrying out the invention]

[0034] The embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows the floating offshore wind power generation substructure 1 in use. The floating offshore wind power generation substructure 1 is a spar-type floating body for supporting the wind power generation device 3 while floating on the sea. The floating offshore wind power generation substructure 1 floats on the sea with its longitudinal direction oriented vertically, and the wind power generation device 3 is positioned above the upper deck 5 of the floating offshore wind power generation substructure 1. The upper deck 5 is, for example, exposed above sea level, and mooring ropes 11 are connected to it. That is, the floating offshore wind power generation substructure 1 is moored to the seabed by mooring ropes 11.

[0035] Figure 2(a) shows the substructure 1 for a floating offshore wind power generation system, and Figure 2(c) is a cross-sectional view taken along line AA of Figure 2(a). The substructure 1 for the floating offshore wind power generation system is mainly composed of cylindrical structures 7, an upper deck 5, a lower deck 9, etc. The lower deck 9 is joined to the lower ends of multiple hollow cylindrical structures 7, and the upper deck 5 is joined to the upper part. In other words, the multiple cylindrical structures 7 are fixed together by the lower deck 9 which forms the upper deck 5, and a sealed space is formed inside the cylindrical structures 7. As mentioned above, the wind power generation device 3 is attached to the upper deck 5.

[0036] Furthermore, as shown in Figure 2(b), multiple cylindrical structures 7 may be joined together by an intermediate floor slab 13 between the upper floor slab 5 and the lower floor slab 9. In other words, the multiple cylindrical structures 7 may be separated vertically by the intermediate floor slab 13.

[0037] The cylindrical structure 7 is constructed by connecting multiple segments or ring members in the longitudinal direction. The manufacturing method of the cylindrical structure 7 will be described in detail later. In the illustrated example, three cylindrical structures 7 are shown side by side, but this is not the only example. For example, there may be two cylindrical structures 7, or four or more.

[0038] Here, the multiple cylindrical structures 7 may be bundled together and fixed without any gaps, but it is preferable to arrange them with gaps between them, as shown in Figure 2(c). By forming gaps between the multiple cylindrical structures 7 in this way, waves can pass through the gaps, and the wave force acting from the side can be suppressed. It is preferable that the gap between the cylindrical structures 7 (C in the figure) is smaller than the outer diameter of the cylindrical structures 7 (D in the figure). If the spacing between the cylindrical structures 7 becomes too wide, the characteristics of a spar-type float (for example, the total length being more than 5 times the outer diameter of the circumscribed circle of the multiple cylindrical structures 7) will decrease, and the effect of separating into multiple cylindrical structures 7 will be reduced.

[0039] Furthermore, it is desirable that the lower deck 9 extends outward beyond the outermost periphery of the cylindrical structure 7 (Figure B). In this way, by allowing at least a portion of the lower deck 9 to extend outward beyond the cylindrical structure 7 in a plan view, this protruding portion acts as resistance to the oscillation of the floating offshore wind power generation substructure 1 when it is floating on the sea, thereby suppressing oscillation. For this reason, for example, the size of the lower deck 9 may be larger than the size of the upper deck 5. Note that the shapes of the lower deck 9 and upper deck 5 are not limited to the examples shown.

[0040] Furthermore, the cylindrical structure 7, upper slab 5, lower slab 9, and intermediate slab 13 may be made of concrete or steel. In the following description, each component will be described assuming it is made of prestressed concrete.

[0041] Next, the manufacturing method for the floating offshore wind power generation substructure 1 will be described. Figure 3 shows the manufacturing method for the lower deck 9. Note that the internal reinforcement bars and other components of each member will not be shown in the following description. The lower deck 9 is manufactured by pouring concrete into a formwork 15. At this time, a recess 17 is formed on one surface of the lower deck 9 by the formwork 15. By forming the recess 17 with the formwork 15 in this way, the smoothness of the surface of the recess 17 is increased, and construction can be carried out with high precision. The same applies to the upper deck 5.

[0042] Next, as shown in Figure 4(a), the lower slab 9 is held upright, and multiple ring members 19 are placed on the sides of the lower slab 9. The ring members 19 may be made of prestressed concrete and formed as a single ring, or they may be divided into multiple segments in the circumferential direction, and the multiple segments may be connected in the circumferential direction to form a ring.

[0043] The ring members 19 at the end are fitted into and fixed in the recesses 17 of the lower deck slab 9. For example, tension members are connected to anchoring plates embedded in the lower deck slab 9, and the ring members 19 are pressed against the lower deck slab 9 to join them. Next, other ring members 19 are sequentially placed to the side (right side in the figure) of the existing ring member 19 (left side in the figure), and moved in the direction of the existing ring member 19 (left side in the figure) to connect the ring members 19 together. At this time, since the ring members 19 are placed above the slide 21 with low frictional resistance, they can be easily moved with jacks or the like. Alternatively, the ring members 19 may be placed on trolleys that can move in the direction of the lower deck slab 9, rather than sliding them on the slide 21.

[0044] Furthermore, as shown in Figure 3(b), in order to maintain the spacing between the ring members 19 (cylindrical structures 7), at least some of the ring members 19 (cylindrical structures 7) may be placed on the upper part of the support 23 to maintain the spacing between them and the other ring members 19 (cylindrical structures 7). In this way, gaps can be formed between multiple cylindrical structures 7.

[0045] Furthermore, the lower floor slab 9 is supported by a reaction force member (not shown) to withstand the pressure from the ring member 19. Additionally, one-touch connectors may be used at the connection points between the ring members 19, or they may be connected by tensioning with tensioning members.

[0046] Figure 5 shows the structure of the joint between the ring members 19, and Figures 5(b) to 5(e) are enlarged views of section F in Figure 5(a). Note that water-sealing members are placed between each member to ensure watertightness, but these are not shown in the diagram.

[0047] As shown in Figure 5(b), in addition to circumferential tensioning members (not shown), sheath tubes 25 are embedded in the ring member 19 in the axial direction. The sheath tubes 25 are arranged at predetermined intervals in the circumferential direction. Furthermore, steel plates 27 are placed on at least a portion of the joint surface of the ring member 19. Note that the steel plates 27 may be placed on the entire joint surface (excluding the sheath tubes 25) or only on a portion of it. For example, the steel plates 27 may be placed so as to cover the corners of the outer edge of the ring member 19.

[0048] As shown in Figure 5(c), the ring members 19 are joined together and tensioned by inserting a tensioning member 29 through the sheath tube 25, thereby connecting the ring members 19. In this case, if the mating surfaces of the ring members 19 are made of steel plate 27, the smoothness can be improved, and thus the watertightness can be improved. Furthermore, if the airtightness is low, for example in an airtightness test, the outer circumference of the ring members 19 can be welded, as shown in Figure 5(d), to improve the airtightness with the welded joint 31.

[0049] Furthermore, in areas where the axial tensioning member 29 (sheath tube 25) is not formed, a fitting portion 33 may be formed, as shown in Figure 5(e). For example, by making one side convex and the other side concave and fitting them together, it can function as a positioning and anti-slip portion. Alternatively, both sides of the fitting portion 33 may be concave and a separate key material may be inserted, or the gap in the fitting portion 33 may be fixed with a filler material after joining.

[0050] By repeating the above steps, multiple cylindrical structures 7 of a predetermined length can be constructed. Finally, the upper floor slabs 5 are placed and joined to the ends of the multiple cylindrical structures 7 (ring members 19), and after all joining is complete, the entire structure may be tensioned together with tensioning members.

[0051] Next, we will explain how to install the wind turbine 3 using the floating offshore wind turbine substructure 1. First, we will explain how to install the floating offshore wind turbine substructure 1. After manufacturing the floating offshore wind turbine substructure 1 using the method described above, the entire floating offshore wind turbine substructure 1 is moved to the sea. That is, the floating offshore wind turbine substructure 1 can be assembled in a yard near the quay, and the assembled floating offshore wind turbine substructure 1 can be moved directly to the sea.

[0052] As shown in Figure 6(a), the floating offshore wind turbine substructure 1, while floating on the sea, is towed to the installation site in a tilted position. Next, as shown in Figure 6(b), ballast 37 is introduced into the interior of the floating offshore wind turbine substructure 1 at the installation site. For example, a bulkhead 35 is provided inside the cylindrical structure 7 to divide the space, and seawater is introduced into the space on the lower deck 9 side. The bulkhead 35 may also be formed by the intermediate deck 13. Furthermore, the bulkhead 35 is not necessarily required if the attitude can be controlled by other means.

[0053] As shown in Figure 6(c), by introducing a predetermined amount of ballast 37, the floating offshore wind turbine substructure 1 can be floated in the sea in an upright position. The upper deck 5 will be exposed above sea level. In this way, the floating offshore wind turbine substructure 1 can be towed to the installation site in a horizontal position and then raised to an upright position by introducing ballast 37.

[0054] Next, the installation of the wind power generation device 3 will be described. Figure 7(a) shows the method for assembling the wind power generation device 3. Pile is driven into the seabed of the quay as needed to install the temporary frame 39. Alternatively, the temporary frame 39 may be installed directly on the quay. Next, the base plate 41 is installed on the temporary frame 39.

[0055] Figure 7(b) is a view of section G in Figure 7(a) (viewed from the top surface of the base plate 41). The upper surface of the temporary frame 39 is provided with a fitting portion 43 (protrusion), and a fixing portion 45a is positioned on its outer circumference. The lower surface of the base plate 41 is also provided with a fitting portion 43 (recess), which fits with the fitting portion 43 of the temporary frame 39. The base plate 41 is fixed to the upper part of the temporary frame 39 by the fixing portion 45a.

[0056] Next, the wind turbine 3 is installed on top of the base plate 41. The wind turbine 3 may be assembled on top of the base plate 41, or it may be assembled elsewhere and then fixed to the base plate 41.

[0057] Next, as shown in Figure 8(a), the float 47 is moved below the base plate 41. At this time, the float 47 is submerged to the extent that it does not interfere with the base plate 41. Figure 8(b) is a view from the arrow at section H in Figure 8(a) (viewed from the top surface of the float 47), and the position of the base plate 41 is indicated by a dotted line. The float 47 is roughly U-shaped and is positioned to surround the temporary frame 39 from three directions.

[0058] Next, the float 47 is raised to make contact with the lower surface of the base plate 41. Additionally, a fixing part 45b is provided on the outer circumference of the base plate 41 at the portion that extends from the temporary frame 39, and the float 47 is fixed to the base plate 41 by the fixing part 45b. In this state, by releasing the fixing part 45a between the base plate 41 and the temporary frame 39, the base plate 41 (wind power generation device 3) can be supported by the float 47.

[0059] Next, as shown in Figure 9(a), the float 47 is raised to detach the base plate 41 (wind turbine 3) from the temporary frame 39. For example, by raising the float 47 above the height of the protrusion in the fitting portion 43, the fitting between the base plate 41 and the temporary frame 39 can be released. In this state, as shown in Figure 9(b), the wind turbine 3 supported by the float 47 is towed to the installation site.

[0060] Figure 10(a) shows the wind turbine 3 being towed to the floating offshore wind power substructure 1. As mentioned above, since the float 47 is roughly U-shaped, it can be positioned to surround the upper deck 5 of the floating offshore wind power substructure 1 from three directions, as shown in Figure 10(b). Therefore, the base plate 41 can be positioned on top of the upper deck 5.

[0061] Furthermore, a protrusion similar to the fitting portion 43 formed on the upper surface of the temporary frame 39 described above may be formed on the upper surface of the upper deck 5. In this case, the float 47 is raised to a level where it does not interfere with the base plate 41, or the floating offshore wind power generation submerged structure 1 is lowered, and the base plate 41 is positioned above the upper deck 5.

[0062] Next, as shown in Figure 10(c), the base plate 41 is positioned on the upper deck 5 of the floating offshore wind power generation substructure 1 by the sinking or floating of at least one of the float 47 or the floating offshore wind power generation substructure 1. At this time, the positioning is made easy by using the fitting part described above. Next, the base plate 41 and the upper deck 5 are joined together. At this time, by providing a fixing part on the upper deck 5 in the same positional relationship as the fixing part 45a on the temporary frame 39, the base plate 41 and the upper deck 5 can be fixed in the same position as the fixing of the base plate 41 and the temporary frame 39.

[0063] Subsequently, the fixation between the float 47 and the base plate 41 is released, and the float 47 is slightly lowered, thereby detaching the float 47 from the base plate 41 and moving the float 47 to a safe place. With this, the installation of the wind power generation device 3 is completed.

[0064] As described above, according to this embodiment, since the cylindrical structure 7 is composed of multiple ring members 19, a spar-type floating offshore wind power generation substructure 1 of a desired length can be constructed. Furthermore, by using multiple cylindrical structures 7 compared to a normal single-cylinder spar-type floating structure, the size of each cylindrical structure 7 can be reduced, and excessive thickness can be suppressed. In addition, it is possible to accommodate further enlargement of the wind power generation device 3 by changing the length and number of cylindrical structures 7.

[0065] Furthermore, by deliberately leaving gaps between the multiple cylindrical structures 7, waves can pass through the gaps between the cylindrical structures 7. This makes it possible to suppress the wave force acting on the floating offshore wind power generation substructure 1.

[0066] Furthermore, by partitioning the internal space of the cylindrical structure 7 and introducing ballast, it is possible to adjust the posture of the floating offshore wind turbine substructure 1, as well as the draft and balance when it is upright.

[0067] Furthermore, by making the size of the lower deck 9 larger than the size of the upper deck 5, the lower deck 9 in the sea can function as a motion suppression mechanism for the floating offshore wind power generation substructure 1.

[0068] Furthermore, the floating offshore wind turbine substructure 1 can be easily installed at the installation site by assembling it in a horizontal position near the quay, moving it out to sea, and then erecting it with ballast at the installation site. At this time, the wind turbine 3 can be assembled using a temporary frame 39 and towed to the floating offshore wind turbine substructure 1 using floats 47, thereby assembling the wind turbine 3 onto the floating offshore wind turbine substructure 1 at sea.

[0069] The construction method for the floating offshore wind turbine substructure 1 is not limited to the method described above. For example, as shown in Figure 11(a), a prefabricated building 49 installed near the quay may be used. The prefabricated building 49 is fixed to the seabed with piles as needed, and cranes and the like (not shown in the figure) are positioned there.

[0070] First, in the assembly building 49, the floating offshore wind turbine substructure 1a is assembled in an upright position and then lowered to the seabed by a crane. The floating offshore wind turbine substructure 1a has the same configuration as the floating offshore wind turbine substructure 1. The upper part (upper deck 5) of the floating offshore wind turbine substructure 1a is exposed above sea level.

[0071] Similarly, as shown in Figure 11(b), the floating offshore wind turbine substructure 1b is assembled in the assembly building 49. The floating offshore wind turbine substructure 1b has the same configuration as the floating offshore wind turbine substructure 1.

[0072] Next, as shown in Figure 12(a), the floating offshore wind turbine substructure 1b, which was assembled later, is moved onto the floating offshore wind turbine substructure 1a, which was assembled earlier, and the two are joined together. That is, the upper deck 5 of the floating offshore wind turbine substructure 1a and the lower deck 9 of the floating offshore wind turbine substructure 1b are joined together. In this case, the joint between the floating offshore wind turbine substructures 1a and 1b functions as the intermediate deck 13 shown in Figure 2(b). At this time, the floating offshore wind turbine substructure 1a, which was assembled earlier, is already on the bottom, making the work easier. If it is difficult to get the floating offshore wind turbine substructure 1a to the bottom, the floating offshore wind turbine substructure 1a may be fixed to the assembly building 49.

[0073] In this way, by joining multiple short floating offshore wind turbine substructures, a floating offshore wind turbine substructure 1 of the desired length can be constructed. After all joining is complete, it can be towed to the installation site by float 47 and installed using the same procedure as described above. In this way, by dividing the floating offshore wind turbine substructure 1 into multiple sections in the longitudinal direction and joining them, the floating offshore wind turbine substructure can also be assembled in an upright position.

[0074] Figure 13 shows yet another method. In Figure 13, a prefabricated building is installed near the quay, and the floating offshore wind power generation substructure 1a is constructed in an upright position. Specifically, multiple ring members 19 are placed on the lower deck 9 on the ground to form multiple cylindrical structures 7 of a predetermined length, and the upper deck 5 is placed on the upper ends of the multiple cylindrical structures 7 and joined to the cylindrical structures 7 to construct the floating offshore wind power generation substructure 1a. Note that the cylindrical structures 7 may be connected horizontally instead of being constructed vertically, as shown in Figure 4.

[0075] The assembled floating offshore wind turbine substructure 1a is lowered to the seabed, secured to a float 47, and the float 47 is raised and towed to a deeper location. Next, the floating offshore wind turbine substructure 1a is lowered to the seabed so that its upper part is above the water surface. Then, another floating offshore wind turbine substructure 1b, assembled in the same manner, is installed and joined on top of the lowered floating offshore wind turbine substructure 1a using a crane vessel or a barge with a crane. A method of fixing, floating, and connecting using floats may also be used.

[0076] Subsequently, the structure is moved to a deeper location, and another floating offshore wind turbine substructure 1c is installed and joined to the bottomed floating offshore wind turbine substructure 1b using a crane vessel or a barge with a crane. By repeating the above process, a floating offshore wind turbine substructure 1 of the desired length can be constructed. The bottoming point can be a smooth location, or an artificial mound or temporary platform may be used. If there is no suitable water depth for bottoming, the pre-assembled floating offshore wind turbine substructure 1a may be fixed to the crane vessel.

[0077] Furthermore, when using the intermediate deck 13, the sizes of the upper and lower cylindrical structures of the intermediate deck 13 may be changed. Figure 14(a) shows a floating offshore wind power generation substructure 1 in which the upper and lower cylindrical structures 7a and 7b of the intermediate deck 13 have different sizes (outer diameter, thickness), and Figure 14(b) is a cross-sectional view taken along line II of Figure 14(a). As shown in Figure 14(a), in this case, by relatively increasing the size of the lower cylindrical structure 7a of the intermediate deck 13, the center of gravity can be lowered, thereby improving oscillation stability. Also, by decreasing the size of the upper cylindrical structure 7b, the area of ​​the cylindrical structure 7b that receives waves can be reduced, and the gap between the cylindrical structures 7b can be increased, thereby improving wave escape near the sea surface and suppressing the effects of waves.

[0078] As shown in Figure 14(b), the cylindrical structure 7b may be arranged on the same axis as the cylindrical structure 7a, or as shown in Figure 14(c), the axis may be offset. In either case, the diameter of the cylindrical structure 7b will be smaller, which will suppress the effects of waves. Also, for example, in Figure 14(c), the cylindrical structure 7b is arranged closer to the center, which will allow the size of the upper deck 5 to be reduced. Furthermore, the length and cross-sectional shape of the cylindrical structures 7a and 7b may be changed, and the number of cylindrical structures 7a and 7b may also be changed.

[0079] Furthermore, a portion of the substructure 1 for the floating offshore wind power generation can also be used as an artificial reef. In the example shown in Figure 15, an artificial seaweed bed 51 is formed on the outer surface of the cylindrical structure 7, which is close to the water surface where sunlight is easily received. The artificial seaweed bed 51 is formed by fixing ropes, etc., to which the sporophytes and gametophytes of seaweed are attached, and can promote the growth of seaweed, fish and shellfish, and their juveniles and larvae. If the intermediate deck 13 is relatively close to the water surface and receives sufficient sunlight, the artificial seaweed bed 51 may be formed on the upper surface of the intermediate deck 13 instead of the cylindrical structure 7. The seaweed may also be artificial, which can promote the growth of seaweed, etc., after the floating structure is installed.

[0080] Although embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0081] 1, 1a, 1b, 1c... Substructure for floating offshore wind power generation 3... Wind power generation equipment 5……Upper floor version 7, 7a, 7b...Cylindrical structures 9……Subfloor version 11……Mooring rope 13……Intermediate floor slab 15... Formwork 17………recess 19... Ring component 21... slide 23...Support 25……sheath tube 27……Steel plate 29……Tension material 31... Welded section 33…Matching part 35……Bulkhead 37... Ballast 39... Temporary stand 41……Basic edition 43…Matching part 45a, 45b……Fixed part 47... Float 49…Assembly building 51……Artificial seaweed bed

Claims

1. A substructure for floating offshore wind power generation, The upper floor slab on which the wind turbines will be installed, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The cylindrical structure is constructed by connecting a plurality of ring members in the longitudinal direction. The cylindrical structure is made of prestressed concrete. A substructure for a floating offshore wind power generation system, characterized in that at least a portion of the joint surfaces between the ring members is made of steel.

2. A substructure for floating offshore wind power generation, The upper floor slab on which the wind turbines will be installed, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The cylindrical structure is constructed by connecting a plurality of ring members in the longitudinal direction. A gap is formed between the multiple cylindrical structures through which waves can pass. The gap is smaller than the outer diameter of the cylindrical structure. The floating body is of the spar type, and its total length is five times or more the outer diameter of the circumscribed circle of the multiple cylindrical structures. A floating offshore wind turbine substructure characterized by the following features.

3. A substructure for floating offshore wind power generation, The upper floor slab on which the wind turbines will be installed, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The cylindrical structure is constructed by connecting a plurality of ring members in the longitudinal direction. The size of the lower floor slab is larger than the size of the upper floor slab, and the lower floor slab extends outward from the outermost part of the cylindrical structure. The floating body is of the spar type, and its total length is five times or more the outer diameter of the circumscribed circle of the multiple cylindrical structures. A floating offshore wind turbine substructure characterized by the following features.

4. The floating offshore wind power generation substructure according to any one of claims 1 to 3, characterized in that a partition wall is provided inside the cylindrical structure to divide the space.

5. The floating offshore wind turbine substructure according to claim 2 or 3, characterized in that the cylindrical structure is made of prestressed concrete.

6. The floating offshore wind turbine substructure according to claim 2 or 3, characterized in that the cylindrical structure is made of steel.

7. The floating offshore wind power generation substructure according to any one of claims 1 to 3, characterized in that a plurality of the cylindrical structures are further joined together by an intermediate deck between the upper deck and the lower deck.

8. A method for constructing a floating offshore wind turbine substructure according to any one of claims 1 to 3, The process involves holding the lower floor slab in an upright position and arranging and joining multiple ring members to the sides of the lower floor slab, A step of sequentially arranging other ring members to the side of an existing ring member, moving them in the direction of the existing ring member to connect them, thereby forming a plurality of cylindrical structures of a predetermined length, The process involves placing the upper floor plate at the ends of the multiple cylindrical structures and joining them to the cylindrical structures, A construction method for a floating offshore wind turbine substructure, characterized by comprising the following:

9. The method for constructing a substructure for a floating offshore wind power generation system according to claim 8, characterized in that, in order to maintain the spacing between the cylindrical structures, at least some of the cylindrical structures are placed on top of the support to maintain the spacing between them and other cylindrical structures.

10. A construction method for a floating offshore wind power substructure comprising: an upper deck to which wind power generation equipment is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are composed of a plurality of ring members connected in the longitudinal direction, and the plurality of cylindrical structures are further joined to each other by an intermediate deck between the upper deck and the lower deck, Step a, which involves arranging multiple ring members on the lower deck on the ground to form multiple cylindrical structures of a predetermined length, Step b involves arranging the upper deck plate at the ends of a plurality of the cylindrical structures and joining them to the cylindrical structures to constitute a substructure for a floating offshore wind power generation system. Step c involves fixing the floating offshore wind turbine substructure to a float, raising the float, and towing it to a deeper location. The process d involves lowering the floating offshore wind turbine substructure so that its upper part is above the water surface, Step e involves joining another floating offshore wind power generation substructure to the upper part of the floating offshore wind power generation substructure, It is equipped with, A method for constructing a substructure for a floating offshore wind power generation system, characterized by repeating steps c to e.

11. A method for installing an offshore wind power generation device, comprising a floating offshore wind power generation substructure comprising an upper deck to which a wind power generation device is attached, a plurality of hollow cylindrical structures joined to the lower part of the upper deck, and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are composed of a plurality of ring members connected in the longitudinal direction, The process of installing a temporary platform on the seabed of the quay, The process of fixing the base plate to the upper part of the temporary frame, The process of installing a wind power generation device on top of the aforementioned base plate, The process involves placing the submerged floats around the temporary frame and raising them to the surface, fixing the base plate and the floats together, and then releasing the fixing between the base plate and the temporary frame. The process involves raising the float, detaching the wind power generation device from the temporary mounting structure, and towing it to the installation site. The process involves towing the floating offshore wind turbine substructure to the installation site in a horizontal position, and then erecting it by introducing ballast. A step of aligning the base plate with the upper deck plate of the floating offshore wind power generation substructure by the sinking or floating of at least one of the float or the floating offshore wind power generation substructure, The process involves joining the base plate and the upper floor plate, and retracting the float, A method for installing an offshore wind power generation device, characterized by comprising the following:

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