Construction Method of Floating Offshore Wind Power Generation Facility

Abstract

To provide a method for efficiently constructing a floating type offshore wind power generation facility with draught of a floating body moored in an installation subject sea area at 20 m or less even when a mounting foothold for the floating body type offshore wind power generation facility is not maintained on dock.SOLUTION: A structure on water 10 is temporarily built in a sea area with water depth of 8 m and more and 20 m and less, a plurality of work areas A are provided in a sea area adjacent to the structure on water 10, and a plurality of sets of assembly parts for a wind power generation device 3 are temporarily placed on the structure on water 10. Assembly work for assembling an assembled body 9 is carried out by installing one set of assembly parts on a floating body 2 grounded on sea bottom SB in a work area A by using a self lifting type barge 20 stopped in an arbitrary work area A, the self lifting type barge 20 is moved to another work area A from the work area A with the assembly work finished, assembly work is carried out on the floating body 2 grounded on the sea bottom SB in the work area A, and additional work is carried out to the assembled body 9 having assembly work finished in advance in parallel to the assembly work.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present invention relates to a construction method for a floating type offshore wind power generation facility. More specifically, it relates to a construction method for a floating type offshore wind power generation facility that can efficiently construct a floating type offshore wind power generation facility with a draft of 20 m or less for a floating body while moored in the installation target sea area without preparing a mounting base (base port) for the floating type offshore wind power generation facility on a quay wall.

Background Art

[0002] A floating type offshore wind power generation facility having a structure in which a wind power generation device is erected on a floating body moored in a sea area is classified into a spar type, a semi-submersible type, a TLP (tension leg platform) type, and a barge (made of concrete) type according to the structure of the floating body. For example, in a spar type floating type offshore wind power generation facility, most of a column-shaped spar type floating body with a height of about 50 m to 100 m is in a submerged state, and a wind power generation device is erected on one huge spar type floating body (see, for example, Patent Document 1). The draft of the spar type floating body in the state of being moored in the installation target sea area is about 50 m to 100 m. On the other hand, in semi-submersible type, TLP type, and barge type floating type offshore wind power generation facilities other than the spar type, the floating body is in a semi-submerged state floating on the sea, and the drafts of the semi-submersible type floating body, the TLP type floating body, and the barge type floating body in the state of being moored in the installation target sea area are each 20 m or less. Specifically, for example, in a semi-submersible type floating type offshore wind power generation facility, a semi-submersible type floating body having a plurality of columns with a height of about 20 m to 40 m and a connecting body (so-called footing member, etc.) connecting the columns is in a state of floating on the sea in a semi-submerged state, and a wind power generation device is erected on one column of the floating body.

[0003] In the construction method of a general spar-type floating offshore wind power generation device, on land such as a quay wall, the spar-type floating body and the tower constituting the wind power generation device are connected in a horizontally laid state, and the integrated unit of the spar-type floating body and the tower is loaded onto a semi-submersible barge in the horizontally laid state as it is, and transported to a sea area with a water depth of 100 m or more. Then, in a sea area with a water depth of 100 m or more, the integrated unit of the spar-type floating body and the tower is launched, and by adjusting the ballast water of the spar-type floating body, the horizontally laid integrated unit is lifted and set upright. After that, the upright integrated unit is towed to the installation target sea area, and the integrated unit is moored in the installation target sea area with a water depth of 100 m or more. Next, using a fixed crane ship, a nacelle hub is installed on the upper part of the tower, and blades are installed on the nacelle hub, thereby completing the erection of the spar-type floating offshore wind power generation device.

[0004] In the invention described in Patent Document 1, it is different from the general construction method in that a bending part is provided in the middle of the tower and the windmill (nacelle hub and blades) is installed on the tower on land. However, also in the invention described in Patent Document 1, the integrated unit of the spar-type floating body (foundation) and the tower of the wind power generation device is assembled on land.

[0005] The floating body and the wind power generation device constituting the floating offshore wind power generation facility are very large in size and very heavy in weight. Therefore, it is difficult to transport the integrated unit of the floating body and the tower over a long distance on land. Therefore, when assembling the assembled body (integrated unit) of the floating body and the tower on land as in the general construction method or the invention described in Patent Document 1, it is necessary to secure a space on land such as a quay wall for mounting the assembled parts of the floating body and the wind power generation device, and to secure a space for performing the assembly work of the assembled body and directly launch the assembled body into the sea. However, in many cases, the ground of a general quay wall does not have the strength to withstand the load of the assembled body. Therefore, in order to prepare a mounting base for the floating offshore wind power generation facility on the quay wall, large-scale construction work such as ground improvement work to improve the bearing capacity of the quay wall and apron is required, and there is a problem that it requires relatively large costs, labor, and time. In particular, when assembling a plurality of assembled bodies on land, it may be difficult to secure a vast space as a mounting base for the floating offshore wind power generation facility on the quay wall.

[0006] In addition, in a general construction method of a spar-type floating offshore wind power facility, it is necessary to perform an operation of lifting and standing up the integrated structure of the spar-type floating body and the tower that was lying horizontally in a sea area with a water depth of 100 m or more. Also in the construction method described in Patent Document 1, it is necessary to change the rear part from the hinge of the tower and the spar-type floating body (foundation) from the lying state to the upright state by means of hinge opening and closing means. Therefore, there is also a problem that highly complex work is required at sea in the conventionally proposed construction methods. Thus, there are various problems in the conventionally proposed construction methods, and there is room for improvement.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide a construction method for a floating offshore wind power facility that can efficiently construct a floating offshore wind power facility with a draft of 20 m or less of the floating body in a state of being moored in the installation target sea area without preparing a mounting base for the floating offshore wind power facility on the quay wall.

Means for Solving the Problems

[0009] In order to achieve the above object, the construction method of the floating offshore wind power generation facility of the present invention has a floating body moored in the installation target sea area and a wind power generation device erected on the floating body. With the floating body moored in the installation target sea area, it is a construction method for concurrently constructing a plurality of floating offshore wind power generation facilities with a draft from the water surface to the lower end of the floating body of 20 m or less. A temporary offshore structure is constructed in a sea area with a water depth of 8 m or more and 20 m or less. A plurality of work areas are provided in the sea area adjacent to the offshore structure. A plurality of sets of assembled parts of the nacelle hub, blades, and tower that make up the wind power generation device are temporarily placed on the offshore structure. Using the crane of a self-elevating barge moored in an arbitrary work area, for the floating body that has landed on the seabed in that work area, a set of the assembled parts temporarily placed on the offshore structure is installed, and an assembly operation is performed to assemble the assembled body in which the wind power generation device is constructed on the floating body. The self-elevating barge is sequentially moved from the work area where the assembly operation has been completed to another work area, and the assembly operation is performed on the floating body that has landed on the seabed in that work area. In parallel, an additional operation including an adjustment operation is performed on the assembled body that has completed the assembly operation earlier. The assembled bodies that have completed the additional operation are sequentially transported by sea to the installation target sea area, and the assembled bodies are moored in the installation target sea area.

Effect of the Invention

[0010] The present invention is a method for constructing multiple floating offshore wind power facilities in parallel, where the draft of the floating body in a moored state in the installation target sea area is 20 m or less, and it can be adopted for the construction of floating offshore wind power facilities of other types (semi-submersible type, TLP type, barge type) excluding the spar type. In the present invention, since a temporary offshore structure is constructed in a relatively shallow sea area with a water depth of 8 m or more and 20 m or less, the cost, labor, and time required for constructing the offshore structure are relatively small. Since the assembled parts of the wind power generation device are temporarily placed on the offshore structure, there is no need to prepare a loading base for the floating offshore wind power facility to temporarily place the assembled parts together on the quay wall. By constructing the offshore structure in a sea area with a water depth of 8 m or more and 20 m or less, it is possible to moor a self-elevating barge near the offshore structure, and the floating body can be easily landed on the seabed near the offshore structure. By using the crane of the self-elevating barge that is not affected by waves and further landing the floating body on the seabed, a set of assembled parts can be installed on the floating body, and the assembly work of assembling the assembled body with the wind power generation device constructed on the floating body can be efficiently performed in a very stable state. Furthermore, a plurality of work areas are provided in the sea area adjacent to the offshore structure, and the self-elevating barge that has completed the assembly work in an arbitrary work area is sequentially moved from the work area where the assembly work has been completed to another work area to perform the assembly work in that work area. In parallel with this, additional work including adjustment work is performed on the assembled body that has completed the assembly work first. As a result, the assembly work and the additional work can be performed in parallel at separate locations, and the self-elevating barge can be efficiently utilized. The assembled body that has completed the additional work is transported by sea to the installation target sea area, and the construction of the floating offshore wind power facility is completed simply by mooring the assembled body in the installation target sea area. Therefore, in the present invention, it is possible to efficiently construct multiple floating offshore wind power facilities (floating offshore wind power facilities of other types excluding the spar type) with a draft of the floating body in a moored state in the installation target sea area of 20 m or less without preparing a loading base for the floating offshore wind power facility on the quay wall.

Brief Description of the Drawings

[0011]

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Embodiment for Carrying Out the Invention

[0012] Hereinafter, the construction method of the floating offshore wind power generation facility of the present invention will be described based on the embodiments shown in the drawings.

[0013] As illustrated in FIG. 1, the floating offshore wind power generation facility 1 has a floating body 2 moored in the installation target sea area and a wind power generation device 3 erected on the floating body 2. In the installation target sea area, the floating body 2 is moored to the seabed SB using a mooring cable 7, an anchor 8, etc. As illustrated in FIG. 1, the present invention is a construction method of the floating offshore wind power generation facility 1 in which, with the floating body 2 moored in the installation target sea area, the draft DF from the water surface to the lower end of the floating body 2 is 20 m or less. In other words, the present invention can be adopted for the construction of floating offshore wind power generation facilities 1 of other types (semi-submersible type, TLP type, barge type) excluding the spar type. The present invention is particularly suitable for the construction of semi-submersible type floating offshore wind power generation facilities 1. In the present invention, an integrated object of the floating body 2 and the wind power generation device 3 before mooring in the installation target sea area is defined as an assembly 9, and the assembly 9 in the moored state in the installation target sea area is defined as the floating offshore wind power generation facility 1.

[0014] In this embodiment, the case of constructing the semi-submersible floating offshore wind power facility 1 will be exemplified. As illustrated in FIG. 1, the semi-submersible floating body 2 is submerged to a predetermined draft DF in the sea area and moored in a semi-submerged state. The wind power generation device 3 has a nacelle hub (an integrated body of a nacelle and a hub) 5 installed at the upper part of a tower 4 extending in the vertical direction, and a plurality of blades 6 are radially arranged on the nacelle hub 5. Inside the nacelle hub 5, electrical equipment such as a generator, a brake device, and a speed increaser (gearbox) is built in, and a power cable connected to the generator is arranged inside the tower 4.

[0015] In this embodiment, a wind power generation device 3 having three blades 6 and in which the tower 4 is composed of three split members 4a is exemplified. The number of blades 6 provided in the wind power generation device 3, the structure of the blades 6, the number of split members 4a constituting the tower 4, etc. are not limited to this embodiment. For example, the blades 6 may have a structure in which a plurality of members are connected, or the tower 4 may be composed of a single long member.

[0016] The length (height) of the tower 4 in the longitudinal direction is about 80 m to 150 m, and the width (thickness) of the tower 4 is about 5 m to 15 m. The weight of the tower 4 is about 1000 t to 2000 t. The length (height) of each split member 4a in the longitudinal direction is about 25 m to 50 m, and the weight of each split member 4a is about 300 t to 700 t. The nacelle hub 5 has a height of about 8 m to 15 m, a longitudinal length of about 15 m to 25 m, and a width of about 7 m to 15 m. The weight of the nacelle hub 5 is about 600 t to 1000 t. The longitudinal length of one blade 6 is about 80 m to 150 m, and the weight of one blade 6 is about 50 t to 90 t.

[0017] The semi-submersible floating body 2 has a plurality of column-shaped columns 2a extending in the vertical direction and a connecting body 2b (so-called footing member) connecting the columns 2a to each other. In this embodiment, the connecting body 2b has a cross-shaped connecting portion in plan view and polygonal support portions provided at four ends of the connecting portion, respectively, and the columns 2a are erected on the four support portions. The lower end of the tower 4 is fixed to one column 2a constituting the semi-submersible floating body 2, so that the wind power generation device 3 is erected on one column 2a. The upper end of the column 2a and the lower end of the tower 4 are joined by, for example, bolt joining or welding.

[0018] The floating body 2 has a structure in which ballast water can be stored (flooded) inside, and by adjusting the amount of stored ballast water, the draft and attitude of the floating body 2 can be adjusted. The length and width of the semi-submersible floating body 2 in plan view are each about 60 m to 100 m, and the height of the position where the column 2a of the semi-submersible floating body 2 is located is about 25 m to 50 m. Note that the structure of the floating body 2, specifically, in the case of the semi-submersible floating body 2, the shape and structure of the column 2a, the shape and structure of the connecting body 2b, the number and arrangement of the columns 2a erected on the connecting body 2b, the position of the column 2a on which the wind power generation device 3 is erected, etc. are not limited to the configuration of this embodiment, and floating bodies 2 with various other configurations can also be adopted. In this embodiment, the semi-submersible floating body 2 is exemplified, but when constructing the TLP-type floating offshore wind power facility 1, a known TLP-type floating body 2 is used, and when constructing the barge-type floating offshore wind power facility 1, a known barge-type floating body 2 is used.

[0019] The working procedure of the construction method of the floating offshore wind power facility 1 of the present invention will be described below. In the present invention, a plurality of floating offshore wind power facilities 1 are constructed in parallel.

[0020] As illustrated in FIGS. 2 and 3, in the present invention, a temporary floating structure 10 is constructed in a sea area where the water depth DW (the depth from the sea surface position WL to the seabed SB) is 8 m or more and 20 m or less. In this embodiment, the case where a jetty 10a is constructed in the sea area is exemplified as the temporary floating structure 10. In the present invention, as the temporary floating structure 10, a floating structure can also be constructed in the sea area. In this embodiment, a floating structure 10 having a rectangular shape in plan view is exemplified. The floating structure 10 has a width that can temporarily accommodate a plurality of sets of assembled parts of the nacelle hub 5, the blades 6, and the tower 4 (split member 4a) that constitute the wind power generation device 3, and has a structure that can withstand the weight of the plurality of sets of assembled parts to be temporarily placed. The members used for constructing the floating structure 10 are transported to the construction target area of the floating structure 10 using a transport ship or the like, and the floating structure 10 is constructed in the sea area by a known method.

[0021] As illustrated in FIG. 2, in this embodiment, as facilities used for mooring a transport ship to the floating structure 10, a temporary mooring facility 15 and a temporary shockproof facility 16 are provided in the vicinity of the floating structure 10. Note that the mooring facility 15 and the shockproof facility 16 are omitted and not shown in the drawings other than FIG. 2.

[0022] The floating structure 10 is preferably constructed in a calm sea area where the influence of waves is small. As illustrated in FIG. 4, preferably, the floating structure 10 may be constructed in the sea area inside a breakwater 40 installed in a bay or the like. The sea area inside the breakwater 40 here indicates a sea area where the influence of waves is reduced by the breakwater 40. The floating structure 10 is preferably constructed in an installation target sea area where the floating offshore wind power generation facility 1 is to be provided, or in a sea area close to a quay 50 where the assembled parts of the wind power generation device 3 are loaded onto a transport ship.

[0023] As illustrated in FIG. 4, in this embodiment, the water structure 10 is constructed in such a direction that the extending direction (longitudinal direction) of the water structure 10 is along the wave direction of the sea area. When the water structure 10 is arranged in such a direction, the area of the surface of the water structure 10 hit by waves can be reduced, which is advantageous for reducing the load and impact applied to the water structure 10 by the waves. For example, when constructing the water structure 10 in a sea area where the height difference of the seabed SB is relatively large from the seawall 50 side (land side) to the offshore side, the water structure 10 may be constructed to extend in a direction intersecting (for example, perpendicular) to the direction from the seawall 50 side to the offshore side. When the water structure 10 is constructed in the above-described direction, the height difference of the seabed SB in the extending direction of the water structure 10 becomes relatively small, so it becomes easier to construct the water structure 10 even in a sea area where the height difference of the seabed SB is relatively large from the seawall 50 side to the offshore side.

[0024] As illustrated in FIG. 2, in the present invention, work areas A for performing the assembly work of the assembly 9 and subsequent additional work are provided at a plurality of locations in the sea area adjacent to the water structure 10. In this embodiment, six work areas A1 to A6 are provided in the sea area adjacent to the water structure 10. As illustrated in FIG. 5, the water structure 10 of this embodiment is configured to be able to temporarily place eight sets of the assembled parts of the wind power generation device 3. The number of work areas A provided in the sea area adjacent to the water structure 10 can be appropriately determined according to the number of floating offshore wind power facilities 1 to be constructed. For example, it can be configured to provide five or less work areas A, or it can also be configured to provide seven or more work areas A.

[0025] The length in the longitudinal direction of the water structure 10 in plan view is set, for example, to be 150 m or more and 450 m or less, and the width is set, for example, to be 80 m or more and 120 m or less. As illustrated in FIG. 3, the height H from the sea surface position WL to the upper surface of the water structure 10 is preferably set to be 1 m or more and 10 m or less, for example. The load-bearing capacity of the water structure 10 is, for example, 1 t / m 2 or more and 15 t / m 2The following settings may be made. The entire range of the offshore structure 10 may be set to the same load-bearing capacity, but it is also possible to set different load-bearing capacities for the area where the assembled parts of the wind power generation device 3 are placed and the area where they are not placed. Also, different load-bearing capacities can be set for each temporary placement area of each assembled part of the wind power generation device 3. Specifically, in the offshore structure 10, the load-bearing capacity of the area where the nacelle hub 5 is placed is, for example, 8 t / m 2 or more and 12 t / m 2 or less. The load-bearing capacity of the area where the split member 4a of the tower 4 is placed is, for example, 3 t / m 2 or more and 8 t / m 2 or less. The load-bearing capacity of the area where the blade 6 is placed is, for example, 1 t / m 2 or more and 5 t / m 2 or less may be set.

[0026] As illustrated in FIG. 3, when constructing the pier 10a as the offshore structure 10, for example, a plurality of support piles 11 driven into the seabed SB, a plurality of girders 12 spanned between the support piles 11, a plurality of deck plates 13 forming the top plate of the pier, and a plurality of braces 14 for reinforcing the connection between the support piles 11 are used to construct the pier 10a. For the support piles 11, for example, steel sections such as H-shaped steel or steel pipe piles are used. For the girders 12 and braces 14, for example, steel sections such as H-shaped steel are used. For the deck plates 13, for example, covering plates are used.

[0027] When constructing a floating structure in the sea area as the offshore structure 10, mooring facilities serving as the base of the floating structure are installed in the sea area using piles or the like. Then, by fixing the float (pontoon) constituting the upper part of the floating structure to the mooring facilities fixed to the seabed SB, a floating structure is constructed as the offshore structure 10. Note that the construction method of the offshore structure 10 in the sea area is not particularly limited, and it may be constructed by a known method.

[0028] The floating structure 10 may be configured to be constructed in a sea area with a water depth of 8 m or more and 20 m or less and to be able to temporarily place a plurality of assembled parts of the wind power generation device 3. The shape and structure of the floating structure 10 are not limited to the configurations exemplified in this embodiment. For example, it is also possible to construct a floating structure 10 having other planar shapes such as an L shape or a cross shape in plan view.

[0029] As illustrated in FIG. 2, in this embodiment, a first work area A1, a second work area A2, and a third work area A3 are respectively provided on one side in the width direction of the floating structure 10, and a fourth work area A4, a fifth work area A5, and a sixth work area A6 are provided on the other side in the width direction of the floating structure 10. The first work area A1 and the fourth work area A4 are provided at the center in the longitudinal direction of the floating structure 10. In the longitudinal direction of the floating structure 10, the second work area A2 is provided on one side of the first work area A1, and the third work area A3 is provided on the other side of the first work area A1. In the longitudinal direction of the floating structure 10, the sixth work area A6 is provided on one side of the fourth work area A4, and the fifth work area A5 is provided on the other side of the fourth work area A4.

[0030] The area of each work area A is set to be an area where the floating body 2 and the self-elevating barge 20 (hereinafter referred to as the SEP barge 20) described later can be respectively arranged. A grounding area BA for grounding the floating body 2 and a mooring area SA for mooring the SEP barge 20 are provided in each work area A. In FIG. 2, the virtual outer frame of each work area A is indicated by a dashed-dotted line, and the virtual outer frame of the grounding area BA and the mooring area SA is indicated by a broken line. Each work area A only needs to have at least the mooring area SA adjacent to the floating structure 10, and the grounding area BA may be spaced apart from the floating structure 10.

[0031] In this embodiment, in the first working area A1 and the fourth working area A4, the mooring area SA and the landing area BA are arranged at positions adjacent to the water structure 10. In each of the second working area A2, the third working area A3, the fifth working area A5, and the sixth working area A6, the mooring area SA is arranged at a position adjacent to the water structure 10, and the mooring area SA is arranged at a position spaced apart from the water structure 10. Preferably, buoys or the like for visualizing the ranges of the respective working areas A (landing area BA, mooring area SA) may be provided in the sea area. Note that it is sufficient for the workers and managers involved in the construction to know the ranges and boundary lines of the respective working areas A, and it is not essential to visualize the ranges of the respective working areas A in the sea area.

[0032] In the present invention, after constructing the water structure 10, a plurality of sets of assembled parts of the nacelle hub 5, the blade 6, and the tower 4 (split member 4a) that constitute the wind power generation device 3 are transported to the water structure 10 using a transport ship equipped with a crane (specifically, for example, a LOLO ship, etc.). Then, using the crane of the transport ship, as illustrated in FIG. 5, the plurality of sets of transported assembled parts are temporarily placed on the water structure 10. Although it is preferable to transport the assembled parts of the wind power generation device 3 to the water structure 10 by sea, when constructing the water structure 10 in a sea area close to the quay 50, for example, the crane 30 arranged on the water structure 10 or the crane arranged on the quay 50 can be used to transport (cargo handling) the assembled parts from the quay 50 to the water structure 10. Also, for example, an aircraft such as a helicopter or a large drone may be used to transport the assembled parts to the water structure 10.

[0033] As illustrated in FIG. 5, in this embodiment, the assembled parts of eight wind power generation devices 3, that is, eight sets of assembled parts, are temporarily placed on the water structure 10. Further, in this embodiment, a mobile crane 30, a tower lifting sling 24, and a work carriage 31 (SPMT: multi-axle carriage) equipped with an erecting device 32 are arranged on the water structure 10. Details of the tower lifting sling 24 and the erecting device 32 will be described later. In this embodiment, a traveling path RW of the crane 30 extending in the longitudinal direction of the water structure 10 is provided at the center of the water structure 10, and the assembled parts of the wind power generation device 3 are temporarily placed on both sides of the traveling path RW. The assembled parts of the wind power generation device 3 are temporarily placed near the respective work areas A1 to A6 in a state where the assembled parts of one wind power generation device 3 are aggregated. The tower lifting sling 24 and the work carriage 31 equipped with the erecting device 32 are arranged near the first work area A1.

[0034] In this embodiment, a pedestal for supporting the nacelle hub 5 is provided on the water structure 10, and the nacelle hub 5 is placed on the pedestal. Further, a pedestal for supporting each divided member 4a constituting the tower 4 is provided on the water structure 10, and the divided member 4a is placed on the pedestal in a state of being laid horizontally. In this embodiment, the three divided members 4a constituting one tower 4 are arranged side by side horizontally. Further, a pedestal having a structure capable of mounting a plurality of blades 6 in a vertically spaced state is provided on the water structure 10, and the plurality of blades 6 are arranged vertically side by side. Each blade 6 is arranged in a horizontally laid state, and a part of the blade 6 arranged at the end of the water structure 10 protrudes from the water structure 10. That is, the water structure 10 may have a width that allows a part of the blade 6 constituting the wind power generation device 3 to protrude. Since the nacelle hub 5 and the divided member 4a are relatively heavy, it is preferable to arrange them without overlapping vertically with each other. Since the blades 6 are large in size and relatively lightweight, it is advisable to arrange the plurality of blades 6 vertically side by side.

[0035] In this embodiment, two sets of assembled parts are temporarily placed near the first working area A1 and the fourth working area A4 respectively. And one set of assembled parts is temporarily placed near the second working area A2, the third working area A3, the fourth working area A4, and the fifth working area A5 respectively. Near the first working area A1 and the fourth working area A4, the blades 6 for two wind turbines 3 are arranged vertically one above the other. Near the second working area A2, the third working area A3, the fourth working area A4, and the fifth working area A5, the blades 6 for one wind turbine 3 are arranged vertically one above the other.

[0036] After temporarily placing the assembled parts of the wind turbine 3 on the water structure 10, the transport ship is moved away from the water structure 10. Then, as illustrated in FIG. 6, the floating body 2 is transported on the sea, and the floating body 2 is successively brought to the seabed SB of the landing area BA of each working area A (A1 to A6) in a state where it has landed. And the SEP ship 20 is stopped in an arbitrary working area A. In this embodiment, first, the floating body 2 is brought to the seabed SB of the landing area BA of the first working area A1, and the SEP ship 20 is stopped in the stopping area SA of the first working area A1.

[0037] During sea transportation, the floating body 2 is floated on the sea with a relatively small amount of ballast water stored, and towed to the vicinity of the water structure 10 using a tugboat or the like. After moving the floating body 2 to the landing area BA, by injecting ballast water into the floating body 2, the floating body 2 is gradually submerged so that the bottom of the floating body 2 lands on the seabed SB. When the seabed SB where the floating body 2 lands is not flat, it is advisable to level or cure the seabed SB in advance before placing the floating body 2 near the water structure 10. Preferably, sandbags or the like are arranged on the seabed SB where the floating body 2 lands to form a flat mound on which the floating body 2 lands, and the floating body 2 is landed on the mound. The floating body 2 is preferably arranged in a direction in which the column 2a for erecting the wind turbine 3 is located on the side of the water structure 10 and the side of the stopping area SA.

[0038] In the present invention, by constructing the offshore structure 10 in a sea area where the water depth DW is 8 m or more and 20 m or less, the semi-submersible floating body 2, the TLP-type floating body 2, and the barge-type floating body 2 can be towed to the working area A near the offshore structure 10. Further, since it is a sea area where the water depth DW is 8 m or more and 20 m or less, each type of floating body 2 can be easily landed on the seabed SB, and the assembled parts of the wind power generation device 3 can be installed on the floating body 2 in the state of being landed on the seabed SB. In other words, in a sea area where the water depth DW is less than 8 m, since the water depth DW is too shallow, it becomes difficult to tow the floating body 2 to the vicinity of the offshore structure 10. In a sea area where the water depth DW exceeds 20 m, since the water depth DW is too deep, it becomes difficult to install the assembled parts of the wind power generation device 3 on the floating body 2 in the state where the floating body 2 is landed on the seabed SB.

[0039] As illustrated in FIGS. 6 and 7, the SEP ship 20 stops with the bow side or the stern side on which the crane 23 is mounted along the side portion of the offshore structure 10. The SEP ship 20 includes a barge main body (platform) 21 movable on the water, a plurality of lifting legs (legs) 22 relatively movable in the vertical direction with respect to the barge main body 21, and a large crane 23 mounted on the barge main body 21. It is preferable to use the self-propelled SEP ship 20 provided with a propulsion device on the barge main body 21, but it is also possible to use the non-self-propelled SEP ship 20 towed and moved without a propulsion device.

[0040] As illustrated in FIG. 7, when stopping the SEP ship 20, each lifting leg 22 is relatively moved downward with respect to the barge main body 21 floating in the sea area so that the lower end of each lifting leg 22 lands on the seabed SB. From that state, by relatively moving the barge main body 21 upward with respect to each lifting leg 22, the barge main body 21 is moved to a position higher than the sea surface, and the barge main body 21 is supported in a hollow state by the lifting legs 22. By raising the barge main body 21 to a height where waves do not reach, the barge main body 21 is in a state where it is not affected by waves.

[0041] The water depth at which the SEP ship 20 can be moored by the elevating legs 22 is generally 40 m or less. In the present invention, since the water depth DW is 8 m or more and 20 m or less, the SEP ship 20 can be moored in a stable state in the working area A near the floating structure 10 when constructing the floating structure 10 in the sea area. In addition, when the seabed SB of the mooring area SA does not have sufficient strength to stably moor the SEP ship 20, it is advisable to perform simple ground improvement such as enhancing the strength of the seabed SB in advance.

[0042] Thereafter, using the crane 23 of the SEP ship 20 moored in the working area A (mooring area SA), an assembly operation is performed to assemble the assembly body 9 in which the wind power generation device 3 is constructed on the floating body 2 in a state of being landed on the seabed SB of the working area A (landing area BA) by installing a set of assembly parts on the floating body 2 in a state of being landed on the seabed SB of the working area A (landing area BA).

[0043] In this embodiment, the assembly body 9 is assembled by installing a set of assembly parts temporarily placed near the first working area A1 on the floating structure 10 on the floating body 2 in a state of being landed on the seabed SB of the first working area A1 using the crane 23 of the SEP ship 20 moored in the first working area A1.

[0044] Specifically, first, using the crane 23 of the SEP ship 20, an operation is performed to install the split member 4a constituting the root portion of the tower 4 temporarily placed on the floating structure 10 on one column 2a of the floating body 2. As illustrated in FIG. 8, in the installation operation of the split member 4a, the tower lifting sling 24 and the erecting device 32 mounted on the work carriage 31 are used. The work carriage 31 may be one that a operator rides on and operates, or one that is remotely operated by a remote controller.

[0045] The lifting tool 24 for tower lifts is used as a lifting tool for the crane 23. The lifting tool 24 for tower lifts is provided with a plurality of clamping portions 24a. By clamping the upper end portions of the split members 4a (the upper end portions when the split members 4a are set upright) in the state where they are laid down horizontally by the respective clamping portions 24a, the lifting tool 24 for tower lifts is connected to the upper end portions of the split members 4a.

[0046] The erecting device 32 is configured to include a holding portion 33, a support portion 34, and a rotation mechanism 35. The support portion 34 is fixed to the loading platform of the work carriage 31, and the holding portion 33 is supported on the upper portion of the support portion 34 via the rotation mechanism 35. The holding portion 33 is rotatably connected to the support portion 34 by the rotation mechanism 35. As illustrated in FIG. 8, in the installation work of the split member 4a, the work carriage 31 equipped with the erecting device 32 is moved to the vicinity of the lower end portion of the split member 4a that is temporarily placed in a laid-down state. Then, the lower portion of the split member 4a is held by the holding portion 33.

[0047] Next, as shown by the arrow in FIG. 8, the upper end portion of the split member 4a is lifted upward toward above the erecting device 32 via the lifting tool 24 for tower lifts by the crane 23, and the lower end portion of the split member 4a is rotated using the erecting device 32 as a guide, thereby erecting the split member 4a as illustrated in FIG. 9. In this embodiment, in the process of moving the upper end portion of the split member 4a directly above the erecting device 32 by the crane 23, the holding portion 33 rotates by the rotation mechanism 35, so that the orientation of the holding portion 33 changes.

[0048] In the work of erecting the split member 4a, the load of the split member 4a may be suspended by the crane 23. By doing so, the load applied to the erecting device 32 and the work carriage 31 can be reduced, and the erecting device 32 can be simply configured.

[0049] As illustrated in Fig. 9, after the dividing member 4a is erected, the erected dividing member 4a is lifted above the erecting device 32 via the tower lift sling 24 by the crane 23. Then, the crane 23 moves the dividing member 4a above one column 2a of the floating body 2 and places the lower end portion of the dividing member 4a on the column 2a. Then, the lower end portion of the dividing member 4a is fixed to the upper end portion of one column 2a of the floating body 2 by bolts, welding, or the like. After that, the connection of the tower lift sling 24 to the upper end portion of the dividing member 4a is released, and the tower lift sling 24 is separated from the upper end portion of the dividing member 4a.

[0050] Next, similarly, the crane 23, the tower lift sling 24, and the erecting device 32 mounted on the work carriage 31 are used to erect the dividing member 4a that constitutes the middle part of the tower 4 temporarily placed on the water structure 10. Then, the crane 23 and the tower lift sling 24 are used to connect the dividing member 4a that constitutes the middle part of the tower 4 to the dividing member 4a that constitutes the base part of the tower 4. After that, similarly, the dividing member 4a that constitutes the upper end part of the tower 4 temporarily placed on the water structure 10 is erected, and the dividing member 4a that constitutes the upper end part of the tower 4 is connected to the dividing member 4a that constitutes the middle part of the tower 4, thereby erecting the tower 4 on the column 2a. Next, as illustrated in Fig. 10, the crane 23 is used to install the nacelle hub 5 temporarily placed on the water structure 10 on the upper part of the tower 4. After that, the crane 23 is used to attach the three blades 6 temporarily placed on the water structure 10 to the nacelle hub 5 respectively. By performing the above operations, as illustrated in Fig. 11, the assembly work of the assembly 9 is completed in the first work area A1.

[0051] After that, in the present invention, as illustrated in FIG. 12, the SEP ship 20 is sequentially moved from the work area A where the assembly work has been completed to another work area A and stopped. Then, as illustrated in FIG. 13, using the crane 23 of the SEP ship 20, the same assembly work is performed on the floating body 2 that has landed on the seabed SB of the work area A. In parallel, additional work including adjustment work is performed on the assembled body 9 that has completed the assembly work in advance. The additional work is preparatory work performed on the assembled body 9 before transporting it to the installation target sea area, and specifically includes pre-assembly work and pre-commissioning work. The pre-assembly work is work for setting the electrical equipment of the assembled body 9. The pre-commissioning work is work for testing and adjusting the electrical equipment of the assembled body 9. In this embodiment, in the work area A where the assembly work has been completed in advance, additional work is performed on the assembled body 9 that has completed the assembly work. The additional work on the assembled body 9 that has completed the assembly work may be performed, for example, by moving the assembled body 9 outside the work area A and performing it in the water area outside the work area A.

[0052] In this embodiment, before the SEP ship 20 finishes the assembly work in the first work area A1, the floating body 2 is transported by sea to the second work area A2 and is kept in a state of landing on the landing area BA of the second work area A2. The SEP ship 20 that has completed the assembly work in the first work area A1 is moved from the mooring area SA of the first work area A1 to the mooring area SA of the second work area A2 and stopped. The work carriage 31 equipped with the erection device 32 is moved to the temporary placement area near the second work area A2. Then, using the crane 23 of the SEP ship 20 stopped in the second work area A2, a set of assembled parts temporarily placed near the second work area A2 on the water structure 10 is installed on the floating body 2 in a state of landing on the seabed SB of the second work area A2 to assemble the assembled body 9. In parallel, in the first work area A1 where the assembly work has been completed in advance, pre-assembly work is performed as additional work on the assembled body 9 that has completed the assembly work, using the crane 30 or the like arranged on the water structure 10.

[0053] After that, following the same work procedure, as illustrated in FIG. 14, the SEP ship 20 is sequentially moved from the work area A where the assembly work has been completed to another work area A and stopped. Then, using the crane 23 of the SEP ship 20, assembly work is carried out on the floating body 2 that has landed on the seabed SB of the work area A. In parallel, in the work area A where the assembly work has been completed in advance, additional work is carried out on the assembled body 9 that has completed the assembly work.

[0054] In this embodiment, before the SEP ship 20 finishes the assembly work in the second work area A2, the floating body 2 is transported by sea to the third work area A3 and is placed in a state where it has landed in the landing area BA of the third work area A3. The SEP ship 20 is moved from the mooring area SA in the second work area A2 where the assembly work has been completed to the mooring area SA in the third work area A3 and stopped. The work carriage 31 equipped with the erection device 32 is moved to a temporary placement area near the third work area A3. Then, using the crane 23 of the SEP ship 20 stopped in the third work area A3, a set of assembled parts temporarily placed near the third work area A3 on the water structure 10 is installed on the floating body 2 in a state where it has landed on the seabed SB of the third work area A3 to assemble the assembled body 9. In parallel, in the second work area A2 where the assembly work has been completed in advance, pre-assembly work is carried out as additional work on the assembled body 9 that has completed the assembly work.

[0055] In the work area A where the pre-assembly work has been completed, next, pre-commissioning work is carried out as additional work on the assembled body 9. And for the assembled body 9 confirmed to have no abnormality in the wind power generation device 3 in the pre-commissioning work, the amount of stored ballast water in the floating body 2 is sequentially reduced to make it float from the seabed SB. Then, with the assembled body 9 floating on the sea, a tugboat or the like is used to transport the assembled body 9 to the installation target sea area by sea. In this embodiment, while the assembly work is being carried out in the third work area A3, the additional work (pre-commissioning work) is completed in the first work area A1, and before the assembly work in the third work area A3 is completed, the assembled body 9 that has completed the additional work is moved outside the first work area A1.

[0056] As illustrated in FIG. 1, the assembled body 9 after the additional work is transported to the sea area where it is to be installed, and in the sea area where it is to be installed, the assembled body 9 (floating body 2) is moored to the seabed SB using a mooring cable 7, an anchor 8, etc. Then, a submarine cable is connected to the wind power generation device 3, and the final operation confirmation (so-called final commissioning) of the floating type offshore wind power facility 1 is carried out. Thus, the construction of the floating type offshore wind power facility 1 is completed.

[0057] As illustrated in FIG. 15, in the work area A where the assembled body 9 is transported to the sea area where it is to be installed, the newly transported floating body 2 is made to land on the seabed SB. In this embodiment, until the assembly work is completed in the third work area A3, the floating body 2 is transported to the first work area A1 and is made to land in the landing area BA of the first work area A1.

[0058] After that, in the same work procedure, as illustrated in FIG. 15, the SEP ship 20 moves from the third work area A3 where the assembly work is completed to the first work area A1 and stops. The work carriage 31 equipped with the erection device 32 is moved to the temporary placement area near the first work area A1. In this embodiment, in the first work area A1, the positions of the landing area BA and the stopping area SA are arranged differently in the first work and the second work so that the SEP ship 20 can stop at a position close to a set of assembled parts temporarily placed near the first work area A1.

[0059] Next, using the crane 23 of the SEP ship 20 stopped in the first work area A1, assembly work is carried out on the floating body 2 that has landed on the seabed SB in the first work area A1. In parallel, in the third work area A3 where the assembly work has been completed in advance, pre-assembly work is carried out on the assembled body 9 on which the assembly work has been completed. In the second work area A2 where the pre-assembly work has been completed, pre-commissioning work is carried out. The assembled body 9 in which no abnormality has been confirmed in the wind power generation device 3 is lifted from the seabed SB, transported to the sea area where it is to be installed, and the assembled body 9 is moored in the sea area where it is to be installed.

[0060] In this embodiment, before the SEP ship 20 finishes the second assembly operation in the first work area A1, the floating body 2 is transported by sea to the fourth work area A4 and is placed in a state where it has landed on the landing area BA of the fourth work area A4. After that, in the same operation procedure, as illustrated in FIG. 16, the SEP ship 20 moves from the first work area A1 where the assembly operation has been completed to the fourth work area A4 and stops. The work carriage 31 equipped with the erecting device 32 is moved to a temporary placement area near the fourth work area A4. Then, using the crane 23 of the SEP ship 20 that has stopped in the fourth work area A4, an assembly operation is performed on the floating body 2 that has landed on the seabed SB of the fourth work area A4. In parallel with this, in the first work area A1 where the assembly operation has been completed first, a pre-assembly operation is performed on the assembled body 9 that has completed the assembly operation. In the third work area A3 where the pre-assembly operation has been completed, a pre-commissioning operation is performed. The assembled body 9 that has been confirmed to have no abnormality in the wind power generation device 3 is lifted from the seabed SB and transported by sea to the installation target sea area, and the assembled body 9 is moored in the installation target sea area.

[0061] After that, in the same operation procedure, while sequentially moving the SEP ship 20 and the work carriage 31 equipped with the erecting device 32 from the fourth work area A4 to the fifth work area A5, from the fifth work area A5 to the sixth work area A6, and from the sixth work area A6 to the fourth work area A4, the assembly operation, the additional operation, and the operation of transporting the assembled body 9 that has completed the additional operation by sea to the installation target sea area and mooring it are performed in parallel in separate work areas A, respectively, to construct a total of eight floating offshore wind power facilities 1.

[0062] When constructing a floating offshore wind power facility 1 with 8 or more bases, after completing the assembly work, additional work, and the offshore transportation work of the assembly body 9 in the first to third work areas A1 to A3, when the SEP ship 20 and the floating body 2 are not arranged in the first to third work areas A1 to A3, a transport ship for transporting the assembled parts of the wind power generation device 3 is stopped in the sea area on the side of the first to third work areas A1 to A3 of the water structure 10, and a plurality of sets of the assembled parts of the wind power generation device 3 are newly temporarily placed. Then, the transport ship is moved away from the water structure 10, and the floating body 2 is transported offshore to the landing areas BA of the first to third work areas A1 to A3 respectively, and the floating body 2 is landed on the seabed SB of the landing areas BA of the respective work areas A1 to A3.

[0063] And the SEP ship 20 that has completed the second assembly work in the fourth work area A4 is moved from the fourth work area A4 to the first work area A1 and stopped. Then, using the crane 23 of the SEP ship 20 stopped in the first work area A1, assembly work is performed on the floating body 2 that has landed on the seabed SB of the first work area A1. After that, the construction of the floating offshore wind power facility 1 with 9 or more bases is carried out in the same manner as the above-described work procedure.

[0064] In this way, by performing the work of temporarily placing the assembled parts of the wind power generation device 3 on the water structure 10, the assembly work, the additional work, and the work of transporting and mooring the assembled body 9 that has completed the additional work to the installation target sea area in parallel, a large number of floating offshore wind power facilities 1 can be constructed in parallel.

[0065] After finishing using the water structure 10 as a manufacturing base, the water structure 10 is removed from the sea area. When the pier 10a is constructed as the water structure 10 as in this embodiment, by filling the holes in the seabed SB where the support piles 11 were inserted, the state of the seabed SB is restored to the state before constructing the water structure 10.

[0066] As described above, the present invention enables the parallel construction of multiple floating offshore wind power facilities 1 with a draft of the floating body 2 of 20 m or less while being moored in the installation target sea area, and can be adopted for the construction of floating offshore wind power facilities 1 of other types excluding the spar type. In the present invention, since the temporary offshore structure 10 is constructed in a relatively shallow sea area where the water depth DW is 8 m or more and 20 m or less, the cost, labor, and time required for the construction of the offshore structure 10 are relatively small. When constructing the pier 10a as the offshore structure 10 as in this embodiment, since it is a relatively shallow sea area, the length of the support pile 11 driven into the seabed SB is relatively short, and the cost, labor, and time required for the construction of the pier 10a are relatively small. Even when constructing a floating structure as the offshore structure 10, since it is a relatively shallow sea area, the work of fixing the mooring equipment constituting the floating structure to the seabed SB can be performed relatively easily, and the cost, labor, and time required for the construction of the floating structure are relatively small.

[0067] In the present invention, since the assembled parts of the wind power generation device 3 are transported to the offshore structure 10 and temporarily placed on the offshore structure 10, there is no need to prepare a loading base for the floating offshore wind power facility 1 where the assembled parts are temporarily placed together on the quay wall 50. That is, to prepare a loading base for the floating offshore wind power facility 1 on land, large-scale construction such as ground improvement work to improve the bearing capacity of the quay wall 50 is required, which requires a relatively large amount of cost, labor, and time. However, in the present invention, there is no need to perform such large-scale construction of the quay wall 50, nor is it necessary to secure a large space behind the quay wall 50. In the present invention, since the offshore structure 10 is constructed in a sea area with a relatively shallow water depth DW, there is also an advantage that it is easy to secure the installation location of the offshore structure 10 within the harbor area.

[0068] Further, in the present invention, by constructing the offshore structure 10 in a sea area where the water depth DW is 8 m or more and 20 m or less, it is possible to moor the SEP ship 20 in the vicinity of the offshore structure 10, and the floating body 2 can be easily landed on the seabed SB in the vicinity of the offshore structure 10. By using the crane 23 of the SEP ship 20 that is not affected by waves, and further by landing the floating body 2 on the seabed SB, the work of assembling the assembly 9 can be efficiently performed in a very stable state.

[0069] Furthermore, in the present invention, a plurality of work areas A are provided in the sea area adjacent to the water structure 10, and the SEP ship 20 that has completed the assembly work in an arbitrary work area A is moved from the work area A where the assembly work has been completed to another work area A, and the assembly work is carried out in that work area A. In parallel therewith, for the assembly body 9 that has completed the assembly work in advance, additional work including adjustment work is carried out. Thereby, the assembly work and the additional work can be carried out in parallel at separate locations, and the SEP ship 20 can be utilized efficiently.

[0070] Generally, the additional work requires a period of about one month. For example, when carrying out the additional work on the assembly body 9 that has completed the assembly work at a location different from the work area A, it is necessary to secure a destination for the movement of the assembly body 9, and time and labor are also required for the work of floating the assembly body 9 and moving it to another location. In contrast, in the present invention, while continuously carrying out the additional work on the assembly body 9 that has completed the assembly work in the work area A near the water structure 10, it is possible to carry out the assembly work of another assembly body 9 in parallel in other work areas A.

[0071] And since the period suitable for construction with a mild working environment in the sea area is limited to a certain extent, if the construction is not completed during the suitable period, it is necessary to stop the construction until the period suitable for the construction of the next year. Even when constructing a large number of floating offshore wind power facilities 1 under such conditions where there are restrictions on the construction period, according to the present invention, it is possible to construct efficiently without securing a place for carrying out additional work on the assembly body 9 in the quay water area or the like. That is, according to the present invention that can reduce the cycle time for sequentially constructing a large number of floating offshore wind power facilities 1, it is extremely advantageous for shortening the time required for the entire construction and constructing a large number of floating offshore wind power facilities.

[0072] The assembled body 9 after the additional work is transported to the installation target sea area, and the construction of the floating type offshore wind power facility 1 is completed only by mooring the assembled body 9 in the installation target sea area. In the present invention, there is no need to perform complicated and high-level work in the installation target sea area. Therefore, in the present invention, even if the loading base of the floating type offshore wind power facility 1 is not prepared on the quay wall 50, a plurality of floating type offshore wind power facilities 1 with a draft of the floating body 2 of 20 m or less in a moored state in the installation target sea area can be efficiently constructed in parallel.

[0073] In addition, in the present invention, since the temporary water structure 10 is constructed in a relatively shallow sea area, after the use of the water structure 10 as a manufacturing base is completed, the water structure 10 can be removed relatively easily. The work of restoring the state of the seabed SB to the state before the construction of the water structure 10 can also be performed relatively easily.

[0074] Furthermore, in the present invention, by providing the water structure 10 for temporarily placing the assembled parts of the wind power generation device 3, it becomes possible to perform the work of transporting the assembled parts by a transport ship other than the SEP ship 20. Therefore, it is not necessary to transport the assembled parts of the wind power generation device 3 by the SEP ship 20, and the SEP ship 20 can be used very efficiently for the assembly work of the assembled body 9. The SEP ship 20 is a special ship, and the number of ships existing in the country is small. Therefore, it is a very great merit for those skilled in the art that the SEP ship 20 can be used efficiently for the assembly work of the assembled body 9 to efficiently construct the floating type offshore wind power facility 1. In addition, in the present invention, by providing the water structure 10, after the transport ship temporarily places the assembled parts on the water structure 10, it can quickly shift to the next transport. Therefore, the operation rate of the transport ship can also be improved by providing the water structure 10.

[0075] When, as in this embodiment, the SEP ship 20 is performing an assembly operation on the floating body 2 in another work area A, if, in parallel therewith, an additional operation on the assembled body 9 is performed in the work area A where the assembly operation has been completed in advance, the additional operation can be continued as it is in the work area A where the assembly operation has been completed. Further, by performing the additional operation in the work area A close to the water structure 10, the crane 30 and the power supply equipment arranged on the water structure 10 can be used. Therefore, with the above-described configuration, the additional operation on the assembled body 9 can be performed very efficiently.

[0076] When the water structure 10 is constructed in the sea area inside the breakwater 40, since the water structure 10 can be constructed in a sea area with less influence of waves, it is advantageous for reducing the labor required for the construction of the water structure 10. Further, since the risk of the water pressure due to waves acting on the floating body 2 in the state of being grounded on the seabed SB and the tower 4 installed on the floating body 2 is reduced, it is also advantageous for reducing the load applied to the floating body 2 and the tower 4. In the present invention, if it is a calm sea area with little influence of waves, for example, the water structure 10 can also be constructed in the sea area outside the breakwater 40 or in the sea area where the breakwater 40 is not provided.

[0077] The number of work areas A provided for the water structure 10 can be appropriately determined according to the number of floating offshore wind power facilities 1 to be constructed and the construction period. However, if six or more work areas A are provided in the sea area adjacent to the water structure 10, it is advantageous for efficiently constructing a large number of floating offshore wind power facilities 1. In particular, when using one SEP ship 20 as in this embodiment, if six work areas A, three on each side of the water structure 10, are provided, each work area A can be effectively utilized in parallel, and a large number of floating offshore wind power facilities 1 can be smoothly and efficiently constructed with one SEP ship 20.

[0078] The number of sets of the assembled parts of the wind power generation device 3 temporarily placed on the water structure 10 can be appropriately determined according to the number of floating offshore wind power facilities 1 to be constructed and the construction period. However, if a water structure 10 capable of temporarily placing 6 or more sets of assembled parts, more preferably 8 or more sets of assembled parts, is constructed, it will be advantageous for efficiently constructing a large number of floating offshore wind power facilities 1. In particular, when six working areas A are provided in the sea area adjacent to the water structure 10 as in this embodiment, constructing a water structure 10 capable of temporarily placing eight sets of assembled parts will be advantageous for smoothly and efficiently constructing a large number of floating offshore wind power facilities 1.

[0079] When configured such that a new floating body 2 is grounded on the seabed SB of the working area A where the assembled body 9 is transported by sea to the installation target sea area as in this embodiment, a plurality of assembled bodies 9 can be assembled in one working area A, so that a large number of floating offshore wind power facilities 1 can be constructed very efficiently. In particular, when the number of sets of the assembled parts temporarily placed on the water structure 10 is larger than the number of working areas A provided in the water structure 10 as in this embodiment, the assembled body 9 can be assembled multiple times in one working area A, which is advantageous for efficiently constructing a large number of floating offshore wind power facilities 1.

[0080] When using the work carriage 31 equipped with the erecting device 32 as in this embodiment, the work of erecting the split members 4a constituting the tower 4 can be stably and efficiently performed. In the conventional method without using the erecting device 32, it was necessary to use two cranes for the work of erecting the split member 4a lying horizontally. Specifically, in the conventional method, the lower end portion and the upper end portion of the split member 4a were respectively suspended in the air by separate cranes, and the upper end portion of the split member 4a was relatively lifted upward with respect to the lower end portion of the split member 4a to erect the split member 4a.

[0081] Therefore, when adopting the conventional method, separately from the crane 23 of the SEP ship 20 that lifts the upper end portion of the split member 4a, a large crawler crane capable of lifting the lower end portion of the split member 4a (for example, in the case of a 300t lifting class, the upper loading weight is 20t / m2 It is necessary to deploy the above on the water structure 10. When deploying a large crawler crane on the water structure 10, it is necessary to secure a relatively large space where the large crawler crane can move on the water structure 10. In addition, it is necessary to design the load-bearing capacity of the entire water structure 10 with a superimposed load capacity that can carry a large crawler crane, which increases the construction period and cost required for the construction of the water structure 10. On the other hand, when using the work carriage 31 equipped with the erecting device 32 as in this embodiment, since it is not necessary to use a large crawler crane, the superimposed load on the water structure 10 can be designed more economically according to the superimposed load capacity of 10 t / m of the work carriage 31 2 or the weight of the assembled parts of the wind power generation device 3. When the erecting device 32 is directly installed on the water structure 10 without using the work carriage 31, the above superimposed load capacity is 10 t / m 2 Perform the necessary curing as follows.

[0082] Also, in the conventional method, in order to erect the divided member 4a with the lower end portion of the divided member 4a lifted by a large crawler crane, it is difficult to stabilize the movement and posture of the divided member 4a when changing the orientation of the divided member 4a, and the divided member 4a is likely to sway in the air. On the other hand, when using the work carriage 31 equipped with the erecting device 32 as in this embodiment, when changing the orientation of the divided member 4a, the path along which the lower end portion of the divided member 4a moves becomes a fixed path by the erecting device 32, and the movement and posture of the divided member 4a are stabilized. Therefore, the operation of erecting the divided member 4a can be performed more safely in a very stable state.

[0083] In the present invention, for example, the erecting device 32 can be configured to be moved by a crane 30 or the like without being mounted on the work carriage 31. Also, in the present invention, the erecting device 32 and the tower lift sling 24 can be arbitrarily used, and the installation work of the divided member 4a can also be performed by another method without using the erecting device 32 and the tower lift sling 24.

[0084] In this embodiment, a case has been exemplified in which the crane 30 of the SEP ship 20 is used to directly move the assembled parts temporarily placed on the offshore structure 10 to the installation position on the floating body 2. However, the assembled parts of the wind power generation device 3 are large in size and weight respectively. Therefore, depending on the size of the crane 30 of the SEP ship 20, it may be difficult to directly move the assembled parts temporarily placed on the offshore structure 10 to the installation position on the floating body 2. In such a case, the SEP ship 20 is stopped so that the side of the SEP ship 20 is along the offshore structure 10, and the crane 23 of the SEP ship 20 is used to transfer the assembled parts temporarily placed on the offshore structure 10 to the SEP ship 20. Then, after changing the direction of the SEP ship 20, the assembled parts transferred onto the SEP ship 20 may be moved to the installation position on the floating body 2 using the crane 30.

[0085] In this embodiment, when assembling the assembly 9 in each work area A, a case has been exemplified in which the orientation of the wind power generation device 3 with respect to the floating body 2 is assembled in the normal orientation when mooring in the installation target sea area. However, since the blades 6 of the wind power generation device 3 are huge, when the wind power generation device 3 is assembled in the normal orientation, the blades 6 may interfere with the work in other work areas A. In such a case, the orientation of the tower 4 with respect to the floating body 2 or the orientation of the nacelle hub 5 with respect to the tower 4 may be assembled in a shifted orientation from the normal orientation so that the blades 6 of the wind power generation device 3 do not interfere with the work in other work areas A. Then, after moving the assembly 9 outside the work area A or after moving the assembly 9 to the installation target sea area, the orientation of the tower 4 with respect to the floating body 2 or the orientation of the nacelle hub 5 with respect to the tower 4 may be corrected to the normal orientation.

[0086] In this embodiment, the case of using one SEP ship 20 is illustrated. However, for example, it is also possible to use two or more SEP ships 20 to construct the floating offshore wind power facility 1. For example, when using two SEP ships 20, while sequentially moving one SEP ship 20 in the working area A (the first to third working areas A1 to A3) in the sea area on one side of the water structure 10, the assembly work of the assembly 9 is carried out. Another SEP ship 20 is used to carry out the assembly work of the assembly 9 while sequentially moving in the working area A (the fourth to sixth working areas A4 to A6) in the sea area on the other side of the water structure 10. In this way, when using two or more SEP ships 20, it is advantageous for constructing a large number of floating offshore wind power facilities 1 in a shorter construction period.

[0087] In the embodiment illustrated in FIG. 17, the case where the water structure 10 is composed of a floating structure 10b is illustrated.

[0088] When the water structure 10 is composed of a floating structure 10b, for example, the assembled parts of the wind power device 3 are placed in advance on the float constituting the top plate of the upper part of the floating structure 10b, and the float in the state where the assembled parts are placed is towed to the construction target area for constructing the water structure 10. Then, the float in the state where the assembled parts of the wind power device 3 are temporarily placed is fixed on the mooring equipment fixed to the seabed SB in the construction target area. By doing so, after constructing the water structure 10, it is not necessary to transport the assembled parts of the wind power device 3 by a transport ship or the like, so the floating offshore wind power facility 1 can be constructed very efficiently. Note that even when the water structure 10 is composed of a floating structure 10b, similar to the case of constructing the pier 10a, after constructing the floating structure 10b in the sea area, the assembled parts of the wind power device 3 can be transported by a transport ship or the like and temporarily placed on the floating structure 10b.

[0089] As described above, the present invention using the water structure 10 and the SEP ship 20 temporarily installed in a sea area with a water depth of 8 m or more and 20 m or less is a method suitable for constructing other types of floating offshore wind power facilities 1 excluding the spar type, and is greatly different in concept from the case of constructing a spar type floating offshore wind power facility.

[0090] For example, when manufacturing a spar-type floating offshore wind power generation device on land using a general construction method or the invention described in Patent Document 1, it is necessary to prepare a manufacturing base for the floating offshore wind power generation device on land such as a quay wall 50.

[0091] Also, for example, when manufacturing an assembly of a spar-type floating body and a wind power generation device with a general structure in a sea area, it is necessary to arrange the spar-type floating body with a height of about 50 m to 100 m in a state of being erected in water, and the spar-type floating body will be arranged in a deep sea area with a water depth of about 100 m to 200 m. In a deep sea area with a water depth of about 100 m to 200 m, the lifting legs 22 of the SEP ship 20 cannot be landed on the seabed SB. Therefore, in the construction of a spar-type floating offshore wind power generation facility, the SEP ship 20 cannot be effectively utilized. In addition, constructing a temporary offshore structure in a deep sea area with a water depth of about 100 m to 200 m requires a lot of costs, labor, and time, and it is necessary to install a large crane such as the one mounted on the SEP ship 20 on the offshore structure. Also, in a deep sea area, a lot of costs and labor are required for the work of removing the offshore structure and the work of restoring the state of the seabed SB.

[0092] As described above, the present invention is a construction method found in consideration of the characteristics of the floating offshore wind power generation facility 1 of other types excluding the spar type, and the technical idea is greatly different from the case of constructing a spar-type floating offshore wind power generation facility.

[0093] In the above, the case of constructing the semi-submersible type floating offshore wind power generation facility 1 has been exemplified, but the same construction method can achieve the same effects when constructing the TLP type floating offshore wind power generation facility 1 or the barge type floating offshore wind power generation facility 1. The present invention can also be adopted when constructing a plurality of types of floating offshore wind power generation facilities 1 in parallel.

Explanation of Reference Numerals

[0094] 1 Floating offshore wind power generation facility 2 Floating body 2a Column 2b Connector 3 Wind power generation device 4 Tower 4a Split member 5 Nacelle hub 6 Blade 7 Mooring cable 8 Anchor 9 Assembly 10 Offshore structure 10a Jetty 10b Floating structure 11 Support pile 12 Girder member 13 Deck plate 14 Brace 15 Mooring equipment 16 Anti-collision equipment 20 Self-elevating barge (SEP barge) 21 Barge body 22 Lifting leg 23 Crane (mounted on the self-elevating barge) 24 Tower lifting sling 24a Clamping part 30 Crane (arranged on the offshore structure) 31 Work carriage 32 Erection device 33 Holding part 34 Support part 35 Rotating mechanism 40 Breakwater 50 Quay wall SB Seabed WL Sea level position A, A1~A6 (1st~6th) Working area BA Landing area SA Berthing area RW Running path

Claims

1. A method for constructing a plurality of floating offshore wind power facilities in parallel, each having a floating body moored in a target installation sea area and a wind power generation device erected on the floating body, and with the draft from the water surface to the lower end of the floating body being 20 m or less in a state where the floating body is moored in the target installation sea area, comprising: Constructing a temporary offshore structure in a sea area with a water depth of 8 m or more and 20 m or less; Providing a plurality of work areas in a sea area adjacent to the offshore structure; Temporarily placing a plurality of sets of assembled parts of a nacelle hub, blades, and tower constituting the wind power generation device on the offshore structure; Using a crane of a self-elevating barge moored in an arbitrary one of the work areas, placing a set of the assembled parts temporarily placed on the offshore structure on the floating body that has landed on the seabed in that work area, and performing an assembly operation of assembling an assembly in which the wind power generation device is constructed on the floating body; The self-elevating barge is sequentially moved from the work area where the assembly operation has been completed to another work area, and the assembly operation is performed on the floating body that has landed on the seabed in that work area. In parallel therewith, an additional operation including an adjustment operation is performed on the assembly that has completed the assembly operation earlier; The assemblies that have completed the additional operation are sequentially transported by sea to the target installation sea area, and the assemblies are moored in the target installation sea area. A method for constructing a floating offshore wind power facility, characterized by this.

2. The method for constructing a floating offshore wind power facility according to claim 1, wherein when the assembly operation is being performed on the floating body in the other work area by the self-elevating barge, in parallel therewith, the additional operation on the assembly is performed in the work area where the assembly operation has been completed earlier.

3. The method for constructing a floating offshore wind power facility according to claim 1 or 2, wherein as the offshore structure, a jetty or a floating structure is constructed in the sea area.

4. The method for constructing a floating offshore wind power facility according to claim 1 or 2, wherein a new floating body is landed on the seabed in the work area where the assembly has been transported by sea to the target installation sea area.

5. The method for constructing a floating offshore wind power facility according to claim 1 or 2, wherein the offshore structure is constructed away from the land, and a plurality of the work areas are provided in regions facing each other with the offshore structure therebetween.

6. The construction method of the floating offshore wind power facility according to claim 1 or 2, wherein a set of the assembly parts is temporarily placed at each location near each of the work areas on the water structure.

7. The construction method of the floating offshore wind power facility according to claim 1 or 2, wherein the water structure is constructed in the sea area inside the breakwater.

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