Floating structure for offshore wind power generation and installation method

Abstract

Disclosed is a floating structure for offshore wind power generation, comprising: a box-shaped structure which can maintain the airtightness of the internal space; and a water inlet / outlet device through which water can be filled into or discharged from the lower portion of the internal space while an air layer exists in the upper portion of the internal space. The structure may be composed of: wall panels that can cover and seal the internal space; and a reinforcing framework, typically including columns and beams, that span the internal space to support the space between the wall panels, wherein the wall panels, columns, and beams may be integrated into a reinforced concrete structure.

Description

Structures and installation methods for floating offshore wind power generation

[0001] The present invention relates to a structure for offshore wind power generation, and more specifically, to a floating substructure for installing a wind turbine in a floating offshore wind power generation and a method for installing the same.

[0002] In relation to global environmental issues, renewable energy power generation technologies that can replace fossil fuel-based power generation are continuously being researched, developed, and commercialized. As one important renewable energy source, the need for floating offshore wind power generation is increasing.

[0003] Furthermore, the importance of floating substructure technology is increasing for stable power generation operations in these floating offshore wind power plants. In other words, the production and installation of suitable floating substructures is essential for stable power generation operations in harsh marine environments.

[0004] To explain further, in general, for onshore wind power generation and fixed offshore wind power generation, there are difficulties in the site selection process, and the closer to land you get, the scarcer the available space becomes, and the sensitivity to environmental impacts increases.

[0005] In comparison, floating offshore wind power plants can be installed far out at sea, making site selection relatively easy. They also have the advantage of being able to maintain strong and constant wind speeds due to less turbulence caused by obstacles, and securing a high utilization rate of wind turbines based on this excellent wind quality.

[0006] However, unlike other types of wind power generation, floating offshore wind power technology must support large loads while floating, while maintaining stability in the easily changing marine environment, which increases the importance of the floating substructure. These substructures can be generally categorized into spar, semi-submersible, tension-leg-platform, and barge types. Hywind Scotland, an early floating offshore wind power project, adopted a spar type due to its high stability. However, since the cylinders were erected and installed using a crane, there were problems with water depth restrictions and high costs due to the rental of a crane vessel. Tension-leg-platform also offers high stability, but its installation cost is very high, which increases the overall cost relatively. Conversely, barge-type structures have low installation and manufacturing costs, but have the problem of relatively low stability.

[0007] Meanwhile, the semi-submersible type has the advantage of being easy to install as it is less affected by the installation location and weather conditions, and thus many projects currently scheduled for development are adopting the semi-submersible type because it has the advantage of being easy to install as it can be installed by developing the Tetraspar structure to reduce the burden of manufacturing costs or by developing the TELWIND structure to use a tugboat to install it.

[0008] However, even in semi-submersible structures, since steel materials and welding construction are mainly used, the material and construction costs are still considerable, and since wind turbines are not usually installed in the center of the structure, there is a problem that it is not easy to stably balance construction and maintenance in various weather and marine environments.

[0009] The present invention is intended to improve the problems of the existing floating offshore wind power generation structures described above, and to provide a floating offshore wind power generation structure and an installation method that can be manufactured at a relatively low cost compared to the existing structure and can be easily installed.

[0010] The purpose of the present invention is to provide a structure and installation method for floating offshore wind power generation suitable for stably constructing and maintaining floating offshore wind power generation facilities.

[0011] The floating offshore wind power generation structure of the present invention for achieving the above purpose is characterized by comprising a box-shaped structure capable of maintaining the airtightness of an internal space and a water inlet / outlet device capable of filling or draining water at the bottom of the internal space while an air layer exists at the top of the internal space.

[0012] In the present invention, the structure may be formed by a wall that can cover and seal the internal space and a reinforcing skeletal structure, typically a column and a beam, that crosses the internal space and supports the space between the walls.

[0013] In the present invention, an air inlet device capable of supplying or withdrawing air to or from an internal space through a wall may be provided, and in this case, a water inlet device capable of supplying or withdrawing water or seawater to or from an internal space through a wall may be in the form of a simple through hole or open pipe.

[0014] In the present invention, the wall, pillars, and beams may be formed of a reinforced concrete structure, a steel-framed concrete structure, or a mixed structure of a reinforced concrete structure and a steel-framed concrete structure.

[0015] In the present invention, a conduit penetrating the floating structure may be installed at the central portion where the wind turbine tower is located. The walls forming this conduit may serve as reinforcing columns to support the weight of the wind turbine, including the wind turbine tower installed above it. Communication lines, power lines, cables, etc. of the wind turbine may pass through this conduit and through the floating structure to be connected to other equipment installed on the seabed or underwater.

[0016] In the present invention, a mooring structure for fixing the floating structure may be installed or coupled to a part of the floating structure.

[0017] The installation method of the present invention is characterized by comprising the steps of manufacturing the floating offshore wind power generation structure of the present invention on land, the step of floating the structure on water and towing it to an installation location offshore, the step of mooring the structure by adjusting the buoyancy of the structure, and the step of installing a wind turbine on the structure.

[0018] According to the present invention, a floating offshore wind power generation structure can be manufactured at a relatively lower cost and easily installed compared to existing structures, thereby reducing the overall construction cost and effort of the floating offshore wind power generation facility.

[0019] According to the present invention, a floating offshore wind power generation facility can be constructed and maintained more stably than before through a structure for floating offshore wind power generation.

[0020] Figure 1 is a perspective front view schematically showing a state in which a floating offshore wind power generation structure according to one embodiment of the present invention is installed together with a mooring device and a wind turbine.

[0021] Figure 2 is a cross-sectional view showing the positions of the side wall, beam, and aerial beam and the joint in the cross-section cut by the horizontal plane passing through line AA in the embodiment of Figure 1.

[0022] Figures 3 and 4 are front views conceptually illustrating a high water level state in which the internal space is filled with a relatively large amount of water and a low water level state in which the internal space is filled with a relatively small amount of water in another embodiment of a floating offshore wind power generation structure of the present invention.

[0023] The present invention will be described in more detail through specific embodiments with reference to the drawings below.

[0024] Figure 1 illustrates a floating offshore wind power generation structure of this embodiment, installed in conjunction with a mooring device and a wind turbine. Figure 2 illustrates the locations of the side wall and its inner surface beams, aerial beams, and joints in a cross-section taken along a horizontal plane passing through line AA of Figure 1.

[0025] Referring to these drawings, the present embodiment will be described. In this embodiment, a floating offshore wind power generation structure (100) is formed by a rectangular parallelepiped wall, columns formed vertically to reinforce the wall from the inside to maintain an internal space surrounded by the wall, and beams and aerial beams formed horizontally.

[0026] The wall is composed of a lower wall (110), four side walls (120), and an upper wall (130), and a beam (112, 122, 132) is formed horizontally on the inner surface of each wall facing the interior space. A column (140) formed vertically is positioned between the beam (132) of the upper wall and the beam (112) of the lower wall, and a horizontally formed air beam (150) is positioned between the beams (122) of the inner surface of the side walls (120) facing each other. A joint (170) is installed at the part where the column (140) and the air beam (150) meet each other in space.

[0027] A structure composed of such columns (140) and aerial beams (150) may appear similar to a frame structure or steel frame structure without a slab. Here, there is one joint (170) between the upper wall beam (132) and the lower wall beam (112), but the number of these joints (170) may increase to two or more depending on the size or thickness of the structure. Similarly, there are six joints (170) along the aerial beams (150) extending horizontally in a straight line between the opposing side walls (120), but the number of these joints (170) may also be a different number depending on the size or width of the structure.

[0028] Walls, beams, columns, and skylights can all be constructed integrally from reinforced concrete, or each element can be formed and joined in different ways. For example, walls can be constructed of reinforced concrete, while columns and skylights can be constructed of steel-framed concrete, with concrete encasing the steel frame. They can also be constructed of hollow square steel tubes, with concrete encasing the outside of the tubes, or they can be constructed of two square steel tubes of different sizes, with concrete filling the space between them.

[0029] Here, a base plate (180) on which a wind turbine (200) tower is installed is installed in the center of the upper wall (130). A central conduit (190) is formed to vertically penetrate this rectangular parallelepiped structure to connect the upper wall (130) and the lower wall (110) below the base plate (180). The wall forming the central conduit (190) can serve as a kind of pillar in this structure, and can support the weight of the wind turbine placed thereon more stably while distributing the weight, and unlike this embodiment, it can also have a configuration in which it is connected to aerial beams.

[0030] These floating offshore wind power generation structures are formed so that the entire internal space surrounded by walls (110, 120, 130) can be sealed from the outside, or at least the upper space filled with air and serving as an air pocket can be sealed from the outside, and an air intake device (410) is installed on the upper part of the structure to allow air to be filled into the upper space serving as an air pocket or to allow air in the upper space to be exhausted to the outside.

[0031] The lower space of the internal space of this structure is filled with water, and a water inlet device (420) is installed to fill the lower space of this structure with water or to drain the water to the outside.

[0032] The air inlet / outlet device (410) or water inlet / outlet device (420) may be configured by a pipe connecting the internal space of the structure to the external space, and a valve and a pump installed along the pipe path. It is preferable that the pump be driven in both directions to enable both filling and removing air or water from the internal space.

[0033] Although not explicitly disclosed in the drawings, in some embodiments, the lower space within the structure may not be sealed from the outside, and may be configured to allow natural water inflow and outflow through a connection port at the bottom of the structure without a separate water inlet and outlet device, and to control the buoyancy of the structure by removing or filling air in the upper space through an air inlet and outlet device. In this case, it may be necessary to determine the location of the air inlet and outlet and the connection port so as to prevent the air in the upper space from escaping to the outside through a path other than the air inlet and outlet device, such as the connection port in the estuary space, and to operate the air inlet and outlet device in accordance with such a design.

[0034] In addition, although not shown here, a management access device (not shown) such as a separate inspection hole may be installed on the upper part of this structure to manage the space inside this structure, and this management access device must be configured to prevent air in the upper space from escaping unintentionally.

[0035] Meanwhile, this structure is equipped with mooring facilities to prevent it from drifting in the sea and from leaving a certain location range.

[0036] The mooring facility may be composed of a non-illustrated subsea fixture, a floating fixture (310) coupled to the structure, and a fixing cable (320) connecting and coupling the subsea fixture and the floating fixture (310). The floating fixture (310) is illustrated here as being installed in four pieces, one at each lower vertex of the rectangular parallelepiped structure, but may be installed in an appropriate number at an appropriate location considering the overall size and weight of the structure, the mechanical durability and strength of the cables and fixtures, etc. Since such mooring facilities are already well known, further detailed description thereof will be omitted here.

[0037] And, although not shown here, the power generated from the wind turbine (200) must be connected to an adjacent power network via a wire cable connected to the wind turbine. The power network may be a substation including an inverter installed on an adjacent offshore structure, and a land-based power facility that receives the power converted by the substation via a submarine wire cable. Since power facilities such as wire cables and communication line cables are typically connected to surrounding facilities via the seabed, such cables must be laid to extend from the wind turbine (200) to the seabed. For this purpose, it is preferable to use a central conduit (190) at the bottom of the wind turbine (200) tower. That is, the structure and the wind turbine can be combined and installed so that separate mooring cables, communication line cables, and power cables pass through the central conduit (190).

[0038] Next, the manufacturing and installation (installation of a wind power generation facility) of the structure of the present invention having such a configuration will be described.

[0039] First, the structure is designed to accommodate the wind turbine's capacity, with the size and internal reinforcement elements of a floating offshore wind turbine structure with air pockets. The above example simply installs vertical columns, horizontal beams, and air beams within the rectangular wall space, with joints where the air beams and columns meet. However, the specific box shape and the reinforcement structure for maintaining the internal space can utilize various structures known from existing construction.

[0040] Also, from a material perspective, the above embodiment can utilize various materials and their combinations known in conventional construction in addition to conventional reinforced concrete structures.

[0041] With regard to construction, the structure of the present invention can generally be constructed on land, particularly in docks used for shipbuilding. While the materials and methods used to construct elements such as walls, columns, beams, aerial beams, and joints may vary, if these elements are formed of reinforced concrete, the construction of the structure can be similar to the construction of a reinforced concrete building. For example, the construction can be carried out by constructing a frame, placing reinforcing bars within the frame, and then filling the frame with concrete.

[0042] In addition, we will manufacture anchors for floating bodies required for mooring structures and also manufacture anchoring cables.

[0043] At this time, if it is possible to secure the mechanical strength of the sealing and connecting parts, it is possible to manufacture this structure by manufacturing some parts as blocks and combining the blocks to manufacture the entire structure, just as when manufacturing a large ship, each part is manufactured as a block and these blocks are combined to manufacture it.

[0044] Once the concrete has sufficiently cured, and auxiliary equipment such as water inlet and air outlet devices have been installed, and the structure has been constructed so that the interior space can be sealed, the structure is filled with water by a method such as filling it with water from a dock, and the size and pressure of the air pocket at the top of the interior space are adjusted so that it floats on water.

[0045] After towing this box-shaped structure to the installation location of the wind turbine with the valves of the water inlet and air inlet devices closed, the structure can be supported by a marine crane or the like.

[0046] The degree of buoyancy of this structure is determined by considering factors such as sea conditions, surrounding environment, and the time allowed to transport it, to minimize water resistance and maintain stability during transport from the manufacturing site to the wind turbine installation site. During transport, buoyancy is typically adjusted so that most of the structure is exposed to air, with only a portion submerged below the water surface, to minimize water resistance. Buoyancy can be specifically controlled by utilizing water and air inlets to maintain an appropriate ratio of water and air layers within the internal space.

[0047] Figures 3 and 4 illustrate a method for controlling the ratio of water and air layers in the internal space of a structure through a conceptual diagram of a simple configuration.

[0048] Figure 3 illustrates a low-water level situation in which the ratio of water to air is relatively small, with air being injected into the internal space of a sealed structure using an air inlet device and water being removed externally through a water inlet device. In this case, the structure's buoyancy is relatively increased, and the portion of the structure exposed above the surrounding water surface increases.

[0049] However, since water is an incompressible liquid and air is a compressible gas, increasing the amount of air while leaving the water unchanged will not increase buoyancy, nor will the structure rise further. Considering this, the water inlet device will become the primary means of buoyancy control. Therefore, in an extreme application of this concept, the amount of air in the internal space could be kept constant, and simply operating the water inlet device could control the relative volume of the water layer relative to the entire internal space, and thus the resulting buoyancy.

[0050] Figure 4 illustrates a high-water level situation in which water is injected from the outside into the interior of a sealed structure through a water inlet device, resulting in a relatively high ratio of the volume of the water layer to the volume of the air layer. In this case, the structure's buoyancy is relatively reduced, and the portion of the structure exposed above the surrounding water surface is also reduced.

[0051] Meanwhile, once the structure arrives at the installation site, water is injected into the internal space through a water inlet device and air is extracted through an air inlet device to create a high water level similar to that shown in Figure 4, lowering the level of the structure's upper wall to facilitate wind turbine installation. Then, the wind turbine is connected to the mooring and upper wall.

[0052] At this time, the degree to which the structure floats on water can be adjusted to suit the surrounding environment and construction convenience at the time of mooring and wind turbine assembly. For example, if the wind turbine is heavy, it is necessary to increase the size of the upper space filled with air within the structure to increase buoyancy. Typically, wind turbines, unless they are small, are not installed in a completed state. Instead, parts of the tower, wind turbine blades, and power generation equipment are sequentially lifted and stacked by crane. It is desirable to adjust buoyancy at each stage.

[0053] Regarding mooring, one end of the mooring cable is attached to a floating anchor to stably secure the structure at a designated sea location, and the other end is attached to a subsea anchor. The subsea anchor is installed on a stable subsea structure, such as rock, ensuring the floating offshore wind power plant is positioned and stabilized within a specific area.

[0054] Once stabilized, the buoyancy of these structures can be adjusted to control mooring conditions, even if not significantly, and can be adjusted during the installation of facilities on top of the structure or during the power generation process to increase stability or increase wind power generation efficiency depending on the surrounding weather and sea conditions.

[0055] The floating offshore wind power generation structures discussed above have a simple structure and a simple and clear operating principle. They can be manufactured very economically using inexpensive concrete among various materials, which has the advantage of minimizing the construction cost of floating offshore wind power generation facilities.

[0056] In addition, since this structure can be manufactured in a stable onshore environment rather than at sea, it is easy to ensure product reliability, and since it is a sealed box-shaped structure, the structure can be towed to the location where the wind turbine is installed while floating on the sea, thereby reducing the cost of transporting the structure.

[0057] In particular, this structure is in the shape of a rectangular box, and if it is manufactured with a low height compared to the area, it is more stable, can be manufactured and maintained, and it is easy to install a wind turbine tower on the flat and wide top of the box, and since the structure is simple and easy to construct, construction costs can be minimized.

[0058] In addition, as in one aspect of the present invention, by installing a central conduit that vertically penetrates the central portion of the floating box structure, i.e., below the wind turbine tower installation portion, transmission and distribution cables, etc. connected from the wind turbine tower can be directly connected to the seabed.

[0059] Additionally, because the floating box structure is filled with seawater with the same specific gravity as the seawater at the location where the wind turbine is installed, it can be more stable against wave currents.

[0060] Although the present invention has been described above through limited examples, these are merely illustrative examples to help understanding of the present invention, and the present invention is not limited to these specific examples.

[0061] Accordingly, a person having ordinary knowledge in the field to which the invention pertains will be able to make various modifications or applications based on the present invention, and it is natural that such modifications or applications fall within the scope of the appended patent claims.

Claims

1. A floating offshore wind power generation structure characterized by comprising a box-shaped structure capable of covering and sealing the internal space with a wall forming a surface so as to maintain the airtightness of the internal space, and a water inlet / outlet device capable of filling or draining water at the bottom of the internal space while trapping air at the top of the internal space.

2. In paragraph 1, A floating offshore wind power generation structure having a reinforcing skeletal structure for supporting the internal space, characterized in that the skeletal structure is formed by vertically formed columns and horizontally formed beams (including aerial beams).

3. In paragraph 1, A floating offshore wind power generation structure characterized in that a central conduit is formed at the center of the box-shaped structure on which a wind turbine is installed upward, penetrating the box-shaped structure upward and downward.

4. In paragraph 1, A floating offshore wind power generation structure equipped with an air intake device capable of supplying or extracting air to or from the internal space through the wall.

5. In paragraph 2, The above wall, the above column and the above beam are formed integrally with a reinforced concrete structure. A floating offshore wind power generation structure featuring:

6. A method for installing a floating offshore wind power generation structure according to any one of clauses 1 to 5, Step of manufacturing the above floating offshore wind power generation structure on land, A step of floating the above floating offshore wind power generation structure on water and towing it to the installation site (location) at sea. A step for controlling buoyancy by controlling the volume ratio occupied by the air layer in the internal space of the above floating offshore wind power generation structure. A method for installing a floating offshore wind power generation structure, comprising a step of installing a wind turbine on the floating offshore wind power generation structure.

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