Floating body structure and offshore wind power generation facility

Abstract

To provide a floating body structure and an offshore wind power generation facility with easy construction alleviating unevenness in buoyancy distribution and weight distribution when a heavy weight object is loaded an offshore wind power generation facility in a simple shape.SOLUTION: A floating body structure 100 provided in a water area for loading a loading matter 12 includes: a floating body 14 in an approximate rotating symmetrical shape regarding a perpendicular line C; a floating body for placement 16 provided to have at least one part of the floating body 14 capable of being replaced for mounting the loading matter 12; and the weight of the floating body for placement 16 is to be lighter than the weight of the floating body 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a floating structure used as a foundation for, for example, an offshore wind power generation facility, and to the offshore wind power generation facility. [Background technology]

[0002] Conventionally, offshore wind power facilities are mainly classified into two types: fixed-bottom type and floating type. Fixed-bottom type is a method in which wind power equipment is installed on a foundation fixed to the seabed, while floating type is a method in which wind power equipment is installed on a floating structure floated on the sea. Fixed-bottom offshore wind power facilities have issues with the feasibility of the structure when the water depth increases, and the cost increases rapidly. For this reason, there is a demand for the practical application of floating offshore wind power facilities. In particular, unlike Europe, Japan has many coasts where the water depth increases rapidly rather than being shallow, so the range of application of floating types is wide.

[0003] Floating structures used in floating systems are mainly classified into four types: barge type (also called pontoon type), TLP type, semi-submersible type, and spar type (see, for example, Non-Patent Document 1). Each type of float is used by mooring it on the ocean with anchors installed on the seabed and mooring lines. Structural materials used to manufacture floating structures include steel, reinforced concrete, and composite structures (hybrid structures) that use both.

[0004] Global external forces acting on floating structures (including ships), such as shear force, bending moment, and torsional moment, are generated by local mismatches between buoyancy distribution and weight distribution. In order to suppress global external forces, it is desirable to make the buoyancy distribution and weight distribution as consistent as possible (see, for example, non-patent document 2).

[0005] In barge-type and semi-submersible floating structures, wind turbines are sometimes mounted asymmetrically due to the shape of the floating structure, which can result in increased external forces such as bending moment acting on the floating structure.

[0006] There are cases where the barge type has a wind turbine mounted in the center of one side (for example, see Non-Patent Document 3). In this case, it is thought that counter ballast was placed on the opposite side to keep it horizontally balanced when there is no external force, but since the degree of local mismatch between the buoyancy distribution and the weight distribution becomes large, it is thought that the bending moment becomes considerably large.

[0007] As an example of a floating structure that focuses on this problem and seeks to design the shape of the floating body so that the buoyancy distribution matches the weight distribution as closely as possible, for example, a floating structure as shown in Patent Document 1 is known. This floating structure includes a plurality of columns configured as columnar buoyants extending vertically, and connectors that connect the plurality of columns in a state where they are deployed horizontally, and an upper structure is connected to the upper parts of at least some of the columns, so that the entire structure is supported on the water, and the buoyancy generated in a column that receives a larger downward load from the upper structure than the other columns is configured to be larger than that of the other columns. At the lower part of each column, a footing that damps the swaying of the column is formed to protrude horizontally.

[0008] Also, floating structures have been proposed in which heavy loads are placed at the center of the float in order to provide symmetry in the loading of the heavy loads (see, for example, Non-Patent Documents 4 and 5). [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Ministry of Land, Infrastructure, Transport and Tourism, Ports and Harbors Bureau website, "Study Group on the Future of Base Ports for Achieving Carbon Neutrality by 2050 (1st Meeting), May 18, 2021, Document 3, p.37", [online], [Retrieved March 15, 2022], Internet<URL:https: / / www.mlit.go.jp / common / 001404624.pdf> [Non-Patent Document 2] Ehime University Graduate School of Science and Engineering, Master's Program, Department of Production and Environmental Engineering, Marine Engineering Special Course Homepage, "7. Loads acting on ships and hull structure, p.6", [online], [Retrieved September 1, 2023], Internet<URL:https: / / www.ehime-naoe.jp / nyuumon / download / 7_Loads_and_Hull_Structure.pdf> [Non-Patent Document 3] New Energy and Industrial Technology Development Organization (NEDO) website, "Demonstration operation of floating offshore wind power generation system begins off the coast of Kitakyushu City," [online], [Retrieved September 1, 2023], Internet<URL:https: / / www.nedo.go.jp / news / press / AA5_101117.html> [Non-Patent Document 4] ResearchGate homepage, "NAUTILUS-DTU10 MW Floating Offshore Wind Turbine at Gulf of Maine", [online], [Retrieved September 1, 2023], Internet <URL:https: / / www.researchgate.net / profile / Josean-Galvan / publication / 328359606_NAUTILUS-DTU10_MW_Floating_Offshore_Wind_Turbine_at_Gulf_of_Maine / links / 5bc885c392851cae21ae803e / NAUTILUS-DTU10-MW-Floating-Offshore-Wind-Turbine-at-Gulf-of-Maine.pdf> [Non-Patent Document 5] SINTEF homepage, "OO-STAR WIND FLOATER - SINTEF", [online], [searched on September 1, 2023], Internet<URL:https: / / www.sintef.no / globalassets / project / eera-deepwind-2018 / presentations / closing_landbo.pdf> [Patent documents]

[0010] [Patent Document 1] International Publication No. 2018 / 096650 Summary of the Invention [Problem to be solved by the invention]

[0011] However, the floating structure of Patent Document 1 has the disadvantage that only the columns and footings directly below the upper structure are larger than the other columns and footings and have an asymmetric shape with respect to the vertical axis, which impairs ease of construction, etc. Also, in a floating structure that does not have footings at the bottom of the columns, it may be necessary to make the columns very large.

[0012] Furthermore, the floating structures of the above-mentioned Non-Patent Documents 4 and 5 have problems in that the structure is complicated, and when it is necessary to load a heavy object (e.g., a wind turbine nacelle) at a high altitude, a crane with an elevation angle is required for the loading work, making the construction difficult.

[0013] The present invention has been made in consideration of the above, and aims to provide a floating structure and offshore wind power generation facility that can reduce unevenness in buoyancy distribution and weight distribution when a heavy load is loaded, has a simple shape, and is easy to construct. [Means for solving the problem]

[0014] In order to solve the above problems and achieve the object, the floating structure according to the present invention is a floating structure that is installed in a water area and carries a mount, and is characterized in that it comprises a floating body having a shape that is approximately rotationally symmetrical with respect to a vertical line, and a mounting float that is installed to replace at least a part of the floating body and on which the mount is placed, and the weight of the mounting float is smaller than the weight of the floating body. Note that the mounting float is a part of the floating body.

[0015] Furthermore, another floating structure according to the present invention is characterized in that, in the above-mentioned invention, the floating body is made of concrete, and the platform float is made of a material including steel, aluminum, resin, lightweight concrete, or a combination of these.

[0016] Moreover, an offshore wind power generation facility according to the present invention is an offshore wind power generation facility equipped with the above-mentioned floating structure, characterized in that the mounted object is a wind power generation equipment. Effect of the Invention

[0017] According to the floating structure of the present invention, the floating structure is installed in a water area and carries a mount, and includes a floating body having a shape that is approximately rotationally symmetrical with respect to a vertical line, and a mounting float that is installed to replace at least a part of the floating body and on which the mount is placed, and since the weight of the mounting float is smaller than the weight of the floating body, it is possible to reduce unevenness in buoyancy distribution and weight distribution, and to suppress the overall external force such as bending force acting on the floating structure. In addition, since the shape is simple, it has an effect of being easy to construct. The mounting float is a part of the floating body.

[0018] Furthermore, according to another floating structure of the present invention, the floating body is made of concrete, and the mounting float is made of materials including steel, aluminum, resin, lightweight concrete, or a combination of these, thereby achieving the effect of easy and inexpensive construction.

[0019] In addition, the offshore wind power generation facility according to the present invention is an offshore wind power generation facility equipped with the above-mentioned floating structure, and since the mounted object is a wind power generation facility, it is possible to reduce unevenness in buoyancy distribution and weight distribution, and to suppress the overall external force such as bending force acting on the offshore wind power generation facility. In addition, since the shape is simple, it is easy to construct. [Brief description of the drawings]

[0020] [Figure 1]FIG. 1 is a schematic perspective view showing a first embodiment of a floating structure and an offshore wind power facility according to the present invention. [Diagram 2] FIG. 2 is a schematic perspective view showing a floating structure and an offshore wind power facility according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic perspective view showing a third embodiment of the floating structure and offshore wind power facility according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the floating structure and offshore wind power generation facility according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments.

[0022] (Embodiment 1) First, a first embodiment of the present invention will be described. As shown in FIG. 1, a floating structure 100 according to the first embodiment is provided on the ocean (water area) and is equipped with a wind power generation facility 12 (mounted object), and includes a barge-type floating body 14 and a mounting float 16 for mounting the wind power generation facility 12. The floating structure 100 is moored on the ocean with anchors and mooring lines (chains, wires, ropes, etc.) (not shown) installed on the seabed, and is used as a foundation for a floating offshore wind power generation facility 10. The floating structure of the present invention is not limited to a foundation for an offshore wind power generation facility, and may be used for other purposes as long as they are suitable for the purpose depending on the characteristics of the floating structure. In this case, any object or equipment may be mounted as a mount for the floating structure.

[0023] The wind power generation facility 12 is a heavy structure comprising blades 18, a nacelle 20 equipped with a wind turbine generator, a wind turbine tower 22 supporting the blades 18 and the nacelle 20, and a substation facility provided at the base of the wind turbine tower 22.

[0024] The float body 14 is a float with a shape that is approximately rotationally symmetrical with respect to a vertical axis C (vertical line), and is composed of a four-sided framework 24 arranged so that the shape when viewed in the vertical direction (up and down direction) is approximately a square ring. When viewed in the vertical direction, the four corners of the float body 14 are chamfered. The upper and lower surfaces of the framework 24 are horizontal, and the side surfaces of the framework 24 are vertical. A footing portion (not shown) that protrudes horizontally is formed on the lower surface of the framework 24. The lower part of the framework 24 is submerged below the water surface WL, and the upper part is exposed above the water surface WL. A cavity (not shown) is provided inside the framework 24, and the framework 24 is divided into a plurality of cavities by partition walls (not shown) that are provided at intervals in the side direction (horizontal direction) of the framework 24. A part of the cavity is used as a ballast tank for adjusting buoyancy.

[0025] The mounting float 16 is a float constituting a part of the float main body 14, and is constituted by a body 24A on one side of the body 24 on the four sides of the float main body 14. This body 24A is a body whose weight is smaller than the weight of the body 24 (part) on one side of the body 24 on the four sides, while keeping the shape of the body 24 as it is. Therefore, the weight of the body 24A constituting the mounting float 16 is smaller than the specific gravity of the bodies 24 on the other three sides of the float main body 14. The wind power generation facility 12 is fixed to the upper surface of the mounting float 16 at the center of the side direction.

[0026] The frame 24 of the floating body main body 14 can be made of a structure using materials including, for example, concrete, reinforced concrete, steel, or a combination of these. The frame 24A of the mounting float 16 can be made of any structure as long as it is lighter than the frame 24, and can be made of, for example, concrete, reinforced concrete, lightweight concrete, steel, aluminum, resin such as foamed resin, or a combination of these. The frame 24 of the floating body main body 14 can be made of concrete, and the frame 24A of the mounting float 16 can be made of steel or lightweight concrete. In this way, construction can be easily and inexpensively carried out.

[0027] According to the floating structure 100 of the first embodiment, the mounting float 16 is lighter than the surrounding frame 24 because the mounting float 16 is lighter than the surrounding frame 24. By adopting a structure in which the weight distribution of the mounting float 16 on which the vertical load of the wind power generation facility 12 acts and the weight distribution of the surrounding frame 24 are made as uniform as possible and close to the buoyancy distribution, it is possible to alleviate the unevenness of the buoyancy distribution and weight distribution occurring in the floating structure 100. In this way, it is possible to suppress external forces such as bending forces acting on the floating structure 100.

[0028] In a conventional floating structure, in order to make the inclination angle in the trimmed state (normal floating state) horizontal, the center of buoyancy and the center of gravity are designed to coincide with each other. However, when a large load is applied to a part of the floating structure and a tilting moment is generated, a counter ballast is required to cancel the tilting moment. In contrast, in the floating structure 100 of the first embodiment, the weight acting on a part of the floating body 14 is alleviated by the lightweight mounting float 16, so that the counter ballast for making the floating body 14 horizontal can be minimized. In particular, when the wind power generation facility 12 is mounted on the floating body 14 asymmetrically with respect to the vertical line C, the counter ballast required for floating the floating body 14 in a horizontal state can be minimized. Minimizing the counter ballast is also effective in alleviating uneven buoyancy distribution and weight distribution.

[0029] The above effect is particularly noticeable in the floating structure 100 having large external dimensions. This is because the bending moment acting on the floating structure 100 increases approximately in proportion to the square of the external dimensions.

[0030] Furthermore, the floating body 14 has a simple shape, which allows for easy construction. In particular, the wind power generation equipment 12 does not necessarily need to be mounted in the center (on the axis C) of the floating body 14, so installation work can be easily performed using a crane from a quay or the like. This is expected to result in a comprehensive cost reduction effect, including the construction method, that exceeds the cost increase caused by adopting a light-weight structure (for example, made of steel or lightweight concrete) for the mounting float 16.

[0031] In the above embodiment, the floating body 14 is configured with a frame 24 that is substantially square and annular in plan view. However, the floating body of the present invention is not limited to this and can be applied to any type of floating body. For example, the floating body may be a barge type with a rectangular box shape. In this case, a part of the floating body may be replaced with a lighter weight floating body for placement. In this case, the same effect as above can be achieved.

[0032] The float body may be of a type having an annular float having a through hole extending in the vertical direction and a communication part that connects the through hole to the outside of the annular float in the horizontal direction, or may further have an island-shaped part. The type having an island-shaped part means that the above-mentioned annular float has a plurality of island-shaped parts that protrude vertically upward from the waterline in an island shape and a connecting part that connects the island-shaped parts underwater. The connecting part is located vertically above the connecting part. In these types, a part of the float body, such as the island-shaped part, may be replaced with a placement float having a low specific gravity. In this way, the same effect as above can be achieved.

[0033] (Embodiment 2) Next, a second embodiment of the present invention will be described. As shown in Fig. 2, the floating structure 200 according to the second embodiment is a semi-submersible type including three columns 26 configured as cylindrical floats extending along the vertical direction, and a horizontal plate-like connector 28 that connects the undersides of the three columns 26 together in a state where they are deployed horizontally. The three columns 26 have the same shape, and are disposed at positions that are approximately rotationally symmetrical with respect to the axis C. The connector 28 has a substantially equilateral triangular shape in a plan view. A cavity (not shown) is provided inside the column 26, and a part of the cavity is used as a ballast tank for adjusting buoyancy.

[0034] Of the three columns 26, the wind turbine tower 22 is installed on the upper surface of one column 26A. The weight of column 26A is set to be smaller than the weight of the other columns 26. The three columns 26 and the connector 28 correspond to the floating body main body of the present invention, and column 26A corresponds to the mounting float of the present invention. Note that the part of the connector 28 directly below column 26A may also be set to be smaller in weight than the other parts of the connector 28. In this case, column 26A and the part of the connector 28 directly below correspond to the mounting float of the present invention.

[0035] The columns 26 and connectors 28 constituting the floating body can be constructed of a structure using materials including, for example, concrete, reinforced concrete, steel, or a combination of these. The columns 26A constituting the mounting float can be constructed of any structure as long as it ensures a weight relationship with the floating body, and can be constructed of a structure using materials including, for example, concrete, reinforced concrete, lightweight concrete, steel, aluminum, resin such as foamed resin, or a combination of these. The components other than the column 26A can be made of concrete, and the column 26A can be made of steel or lightweight concrete. In this way, construction can be performed easily and inexpensively.

[0036] According to the second embodiment, it is possible to obtain the same effects as those of the first embodiment. For example, it is possible to reduce unevenness in buoyancy distribution and weight distribution occurring in the floating structure 200, and it is possible to suppress the overall external force such as bending force acting on the floating structure 200. In addition, since the shape is a well-known simple shape, it can be easily constructed.

[0037] (Embodiment 3) Next, a third embodiment of the present invention will be described. As shown in Fig. 3, a floating structure 300 according to the third embodiment is a semi-submersible type including four columns 30 configured as cylindrical floats extending along the vertical direction, and a horizontal plate-like connector 32 that connects the undersides of the four columns 30 together in a state where they are deployed horizontally. The four columns 30 have the same shape, and are disposed at positions that are approximately rotationally symmetrical with respect to the axis C. The connector 32 is approximately square in plan view. A cavity (not shown) is provided inside the column 30, and a part of the cavity is used as a ballast tank for adjusting buoyancy.

[0038] Of the four columns 30, the wind turbine tower 22 is installed on the upper surface of one column 30A. The weight of column 30A is set to be smaller than the weight of the other columns 30. The four columns 30 and the connector 32 correspond to the floating body main body of the present invention, and column 30A corresponds to the mounting float of the present invention. Note that the part of the connector 32 directly below column 30A may also be set to be smaller in weight than the other parts of the connector 32. In this case, column 30A and the part of the connector 32 directly below correspond to the mounting float of the present invention.

[0039] The column 30 and the connector 32 constituting the floating body can be constructed with a structure using materials including, for example, concrete, reinforced concrete, steel, or a combination of these. The column 30A constituting the mounting float can be constructed with any structure as long as it maintains a large-small relationship in specific gravity with the floating body, and can be constructed with a structure using materials including, for example, concrete, reinforced concrete, lightweight concrete, steel, aluminum, resin such as foamed resin, or a combination of these. The components other than the column 30A can be made of concrete, and the column 30A can be made of steel or lightweight concrete. In this way, construction can be performed easily and inexpensively.

[0040] According to the third embodiment, it is possible to obtain the same effects as those of the second embodiment. For example, it is possible to reduce unevenness in buoyancy distribution and weight distribution occurring in the floating structure 300, and it is possible to suppress the overall external force such as bending force acting on the floating structure 300. In addition, since the shape is a well-known simple shape, it can be easily constructed.

[0041] In the third embodiment, the number of columns 30 may be five or more, and each column 30 may be arranged in a substantially regular polygonal shape in a plan view to form a semi-submersible type. In this case, the wind turbine tower 22 may be mounted on the upper surface of at least one column 30, and the weight of that column 30 may be set to be smaller than the weight of the other columns 30. Even in this case, the same effects as those described above can be achieved.

[0042] As described above, the floating structure according to the present invention is a floating structure installed in a water area and carrying a mount, comprising a floating body having a shape that is approximately rotationally symmetrical with respect to a vertical line, and a mounting float for mounting the mount, which is installed to replace at least a part of the floating body, and the weight of the mounting float is smaller than the weight of the floating body, so that it is possible to reduce unevenness in buoyancy distribution and weight distribution, and to suppress the overall external force such as bending force acting on the floating structure. Also, since the shape is simple, it can be easily constructed.

[0043] Furthermore, according to another floating structure of the present invention, the floating body is made of concrete, and the mounting float is made of materials including steel, aluminum, resin, lightweight concrete, or a combination of these, so that construction can be performed easily and inexpensively.

[0044] According to the offshore wind power generation facility of the present invention, since the offshore wind power generation facility is equipped with the above-mentioned floating structure and the mounted object is a wind power generation equipment, it is possible to reduce unevenness in buoyancy distribution and weight distribution, and to suppress the overall external force such as bending force acting on the offshore wind power generation facility. Also, since the shape is simple, it can be easily constructed.

[0045] The "Sustainable Development Goals (SDGs)" are 17 international goals that were adopted at the United Nations Summit in September 2015. The floating structure and offshore wind power generation facility according to the present embodiment can contribute to achieving one of the 17 SDGs, for example goal 9 "Build resilient infrastructure, promote industry, innovation and infrastructure." [Industrial Applicability]

[0046] As described above, the floating structure and offshore wind power generation facility according to the present invention are useful for mitigating uneven buoyancy and weight distribution when heavy objects such as wind turbines are mounted, and are particularly suited to easy construction due to their simple shape. [Explanation of symbols]

[0047] 10. Offshore wind power generation facilities 12 Wind power generation equipment (onboard equipment) 14 Floating body 16. Floating body for placement 18 Blades 20 Nacelle 22 Windmill Tower 24,24A frame 26,30 Column 26A, 30A Column (floating body for placement) 28,32 Concatenation 100,200,300 Floating Structures C axis (vertical line) WL water surface

Claims

1. A floating structure installed in a water area and carrying a payload, A floating structure comprising a floating body having an approximately rotationally symmetric shape with respect to a vertical line, and a mounting float for placing the mounted object, which is arranged to replace at least a portion of the floating body, and the weight of the mounting float is less than the weight of the floating body.

2. 2. The floating structure according to claim 1, wherein the floating body is made of concrete, and the base float is made of a material including steel, aluminum, resin, lightweight concrete, or a combination of these.

3. An offshore wind power generation facility equipped with the floating structure according to claim 1 or 2, An offshore wind power generation facility, characterized in that the mounted object is a wind power generation facility.

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