Floating offshore wind turbine system, method for transporting floating offshore wind turbine, and floating offshore wind turbine

Abstract

Provided is a floating offshore wind turbine system having a structure useful for replacing large components of a floating offshore wind turbine. A floating offshore wind turbine system having a floating offshore wind turbine, a main floating body, and a mooring body, the floating offshore wind turbine system characterized in that: the floating offshore wind turbine has blades for receiving wind, a hub to which the blades are fixed, a nacelle for storing a generator for converting rotational energy of the hub into electric power, a tower for supporting the nacelle, a sub-floating body for supporting the tower, and a sub-floating body connection part that can be fitted to a transport ship connection part; and the main floating body is moored to the sea bottom by the mooring body, and has a sub-floating body insertion space into which the sub-floating body is inserted.

Description

Floating offshore wind turbine system, method for transporting a floating offshore wind turbine, and floating offshore wind turbine

[0001] The present invention relates to a floating offshore wind turbine system with a disassemblable floating structure, a method for transporting a floating offshore wind turbine, and a floating offshore wind turbine.

[0002] In recent years, wind power generation has been widely adopted worldwide as one of the countermeasures against global warming. The locations of wind power generation are expanding from land to offshore, and offshore installation locations are also expanding from shallow waters where bottom-fixed offshore wind turbines are used to deep waters where floating offshore wind turbines are used. However, because self-elevating vessels (JUVs) cannot be used in deep waters, it has been difficult to replace large parts during maintenance of floating offshore wind turbines, as these require large cranes on the JUVs.

[0003] Therefore, the wind power generation facility of Patent Document 1 is described in the abstract as "a wind power generation facility having a tower that is installed on land or offshore and serves as a support for a generator, a nacelle that is installed on the tower and has the generator built in, and a rotor that is installed at one end of the nacelle and consists of a hub and blades that receives wind and converts it into rotational energy, wherein the wind power generation facility is characterized in that a winch is installed within the nacelle for transporting replacement parts for the generator between the land or offshore and the nacelle." This allows large parts inside the nacelle to be replaced using a winch inside the nacelle.

[0004] Patent Publication No. 2015-110927

[0005] However, the winch in Patent Document 1 is only for replacing parts inside the nacelle, and is not capable of replacing large parts outside the nacelle, such as blades.

[0006] Therefore, an object of the present invention is to provide a floating offshore wind turbine system having a structure that is useful for realizing replacement of large components of the floating offshore wind turbine.

[0007] In order to solve the above problems, the floating offshore wind turbine system of the present invention is a floating offshore wind turbine system having a floating offshore wind turbine, a main floating body, and mooring bodies, wherein the floating offshore wind turbine has blades that catch the wind, a hub to which the blades are fixed, a nacelle that houses a generator that converts the rotational energy of the hub into electricity, a tower that supports the nacelle, a sub-float that supports the tower, and a sub-float coupling part that can be fitted with a transport vessel coupling part, and the main floating body is moored to the seabed by the mooring bodies and has a sub-float insertion space into which the sub-float is inserted.

[0008] According to the floating offshore wind turbine system of the present invention, the sub-floor can be made compact and economically advantageous.

[0009] FIG. 1 is a bird's-eye view of a floating offshore wind turbine system of Example 1 (barge type). FIG. 2 is a side view of the fitted state of the floating offshore wind turbine and transport vessel of Example 1. FIG. 3 is a diagram explaining the procedure for fitting the joints of the floating offshore wind turbine and transport vessel together. FIG. 4 is a bird's-eye view of a tension leg platform type floating offshore wind turbine system. FIG. 5 is a bird's-eye view of a semi-submersible type floating offshore wind turbine system. FIG. 6 is a bird's-eye view of a spar type floating offshore wind turbine system. FIG. 7 is a side view of the fitted state of the floating offshore wind turbine and transport vessel of Example 2.

[0010] Hereinafter, an embodiment of the floating offshore wind turbine system of the present invention will be described with reference to the drawings.

[0011] 1 is a bird's-eye view of a floating offshore wind turbine system 100 according to a first embodiment of the present invention. The floating offshore wind turbine system illustrated here is an offshore power generation system that is installed in a deep sea area at a depth of about 50 to 100 meters, converts offshore wind energy into electricity, and transmits it to an onshore grid, and includes a floating offshore wind turbine 1, a main float 2, a mooring body 3, an offshore cable 4, and a submarine cable 5. Each of these components will be described in detail below.

[0012] The floating offshore wind turbine 1 comprises blades 11 that catch offshore winds, a hub 12 to which the blades 11 are fixed, a nacelle 13 that houses a generator that converts the rotational energy of the hub 12 into electricity, a tower 14 that supports the nacelle 13, a sub-float 15 that is a base that supports the tower 14, and a connecting part 16 that is shaped to be able to fit into a connecting part 61 of a transport ship 6.

[0013] The main float 2 is a float that has a space into which the sub-float 15 of the floating offshore wind turbine 1 can be inserted, and is moored to the seabed by mooring members 3 such as chains while floating on the sea surface SL. Note that Fig. 1 shows an example in which the main float 2 and the sub-float 15 are connected by a connecting member J to form a barge-type structure. The connecting member J is specifically a bolt or weld that firmly connects the main float 2 and the sub-float 15, and can be removed as necessary, for example, when repairing the floating offshore wind turbine 1. The sub-float 15 is not directly moored to the seabed, but is indirectly moored to the seabed via the connecting member J.

[0014] The marine cable 4 is an electric wire that relays the power generated by the generator in the nacelle 13, and the submarine cable 5 is an electric wire that transmits the generated power via the marine cable 4 to the land system.

[0015] In the floating offshore wind turbine system 100 of this embodiment, the manufacturing cost of the floating offshore wind turbine 1 is reduced by downsizing the sub-float 15. In this case, the buoyancy of the sub-float 15 alone is not enough to stably transport the floating offshore wind turbine 1 before or after it is connected to or disconnected from the main float 2, so in this embodiment, buoyancy that compensates for the lack of buoyancy of the sub-float 15 is imparted to the floating offshore wind turbine 1 from the transport ship 6 via the coupling parts 61, 16. This enables the transport ship 6 to transport the floating offshore wind turbine 1 over the sea in a stable state.

[0016] 2 is a side view showing the state in which the floating offshore wind turbine 1 before being connected to the main float 2, or the floating offshore wind turbine 1 after being detached from the main float 2, is being transported by a transport ship 6. As shown in the figure, a coupling part 61 of the transport ship 6 and a coupling part 16 of the floating offshore wind turbine 1 are fitted together, so that the forward and backward movement of the transport ship 6 can be linked to the movement of the floating offshore wind turbine 1.

[0017] As shown in the figure, the floating offshore wind turbine 1 is subjected to downward forces including gravity F1, which is the resultant force of gravity acting on the blades 11, hub 12, and nacelle 13, gravity F2 acting on the tower 14, and gravity F3 acting on the sub-floating body 15. The floating offshore wind turbine 1 is also subjected to upward forces including buoyancy F4 acting on the sub-floating body 15 and buoyancy F5 transmitted from the coupling part 61 of the transport ship 6 via the coupling part 16.

[0018] 2, in order to transport the floating offshore wind turbine 1 in a stable state, the relationship F1 + F2 + F3 = F4 + F5 must be satisfied. Furthermore, by positioning the center of gravity G of the floating offshore wind turbine 1 below the point of action of buoyancy F5 (the contact position between the upper end of the connecting part 61 and the underside of the connecting part 16), stability during transportation can be further improved. In order to lower the position of the center of gravity G, it is advisable to design the sub-floor 15 to have a larger mass, for example.

[0019] 3 is a diagram illustrating the procedure for fitting the coupling portion 16 of the floating offshore wind turbine 1 and the coupling portion 61 of the transport ship 6. Here, the coupling portion 16 of the floating offshore wind turbine 1 has a substantially L-shaped cross section with a vertical portion extending downward from the tip of the horizontal portion fixed to the sub-floor 15, and the coupling portion 61 of the transport ship 6 has a substantially L-shaped cross section with a vertical portion extending upward from the tip of the horizontal portion fixed to the transport ship body, and the vertical portion of the coupling portion 61 is longer than the vertical portion of the coupling portion 16. However, as long as the two can be fitted together, the shapes of the coupling portions 16, 61 are not limited to those exemplified here.

[0020] 3A is a schematic diagram illustrating the relative relationship between the coupling parts 16 and 61 when ballast water is poured into the transport ship 6 and the waterline of the transport ship 6 is raised. In this state, the upper end of the coupling part 61 is lower than the lower end of the coupling part 16, so that the coupling part 61 can be positioned below the coupling part 16 by moving the transport ship 6.

[0021] 3(b) is a schematic diagram illustrating the relative relationship between the coupling parts 16, 61 when ballast water has been discharged from the transport vessel 6 and the waterline of the transport vessel 6 has been lowered. In this state, the upper end of the coupling part 61 is pressed against the lower surface of the horizontal part of the coupling part 16, so that part of the buoyancy of the transport vessel 6 (buoyancy F5) is transmitted to the sub-floor 15 of the floating offshore wind turbine 1 via the coupling parts 61, 16, thereby compensating for the lack of buoyancy of the sub-floor 15. Therefore, by moving the transport vessel 6 in the state shown in FIG. 3(b), the floating offshore wind turbine 1 can be moved in the desired direction with a stable draft.

[0022] In the above explanation, the waterline of the transport ship 6 is raised or lowered by injecting or discharging ballast water into or from the transport ship 6, thereby changing the relative positions of the coupling parts 61 and 16. However, the waterline of the sub-float 15 and the main float 2 can also be raised or lowered by injecting or discharging ballast water into or from the main float 2, thereby changing the relative positions of the coupling parts 61 and 16.

[0023] Although the above describes an example in which a barge-type float is formed by connecting the main float 2 and the sub-float 15, other types of floats may be formed depending on the situation. For example, as shown in the bird's-eye view of Figure 4, a tension leg platform (TLP) type float may be formed, using tension moorings 31 instead of the moorings 3, as shown in the bird's-eye view of Figure 5, a semi-submersible float may be formed, as shown in the bird's-eye view of Figure 6, or a spar-type float may be formed.

[0024] As described above, in this embodiment, the floaters of the floating offshore wind turbine system are composed of a main floater moored to the seabed and a sub-floater to which the wind turbine is fixed, and the two floaters are connected in a manner that allows them to be disconnected, and the sub-floater is equipped with a coupling part that fits into a coupling part of the transport vessel. This allows the buoyancy of the floating offshore wind turbine, which is insufficient when separated from the main floater, to be supplemented by the buoyancy of the transport vessel, so the floating offshore wind turbine can be transported in a stable state even when using the compact and economical sub-floater.

[0025] Next, a floating offshore wind turbine system 100 according to a second embodiment, which is configured as a spar-type or semi-submersible floater, will be described with reference to Fig. 7. Note that a duplicated description of points common to the first embodiment will be omitted.

[0026] 2 of Example 1, with the coupling part 16 of the floating offshore wind turbine 1 and the coupling part 61 of the transport vessel 6 engaged, part of the buoyancy of the transport vessel 6 (buoyancy F5) is transmitted to the floating offshore wind turbine 1. In this case, the horizontal distance from the center of gravity G of the floating offshore wind turbine 1 to the point of action of buoyancy F5 becomes longer, and the moment around the center of gravity G caused by buoyancy F5 becomes larger, which may impair the stability of the floating offshore wind turbine 1 during transportation.

[0027] Therefore, in this embodiment, as shown in the side view of Figure 7 , a support part 62 extending farther from the rear end of the coupling part 61 (more preferably, to directly above the center of gravity G) is installed on the transport ship 6 as a configuration for transmitting part of the buoyancy of the transport ship 6 (buoyancy F5) to the floating offshore wind turbine 1. When this configuration is adopted, the horizontal distance between the point of action of buoyancy F5 and the center of gravity G is shorter than in the example of Figure 2 of Example 1, so the moment around the center of gravity G caused by buoyancy F5 is smaller, and the stability during transportation of the floating offshore wind turbine 1 can be further improved. Although stability during transportation can also be improved by increasing the mass of the sub-floor 15 and lowering the center of gravity G, providing the support part 62 makes it possible to reduce the mass of the sub-floor 15.

[0028] Needless to say, in the configuration of this embodiment, the connection part 16 of the floating offshore wind turbine 1 and the connection part 61 of the transport ship 6 transmit the buoyancy F5 only until the sub-float 15 is supported by the support part 62 of the transport ship 6, or only transmits horizontal forces (such as the traction force of the floating offshore wind turbine 1).

[0029] 100: Floating offshore wind turbine system 1: Floating offshore wind turbine 11: Blade 12: Hub 13: Nacelle 14: Tower 15: Sub-floor 16: Connection part 2: Main float 2A: Tension leg platform type main float 2B: Semi-sub type main float 2C: Spar type main float 3: Mooring body 31: Tension mooring body 4: Marine cable 5: Submarine cable 6: Transport ship 61: Connection part 62: Support part

Claims

1. A floating offshore wind turbine system comprising a floating offshore wind turbine, a main floating body, and mooring bodies, wherein the floating offshore wind turbine comprises blades that catch the wind, a hub to which the blades are fixed, a nacelle that houses a generator that converts the rotational energy of the hub into electricity, a tower that supports the nacelle, a sub-floating body that supports the tower, and a sub-floating body coupling part that can be fitted with a transport vessel coupling part, and the main floating body is moored to the seabed by the mooring bodies, and has a sub-floating body insertion space into which the sub-floating body is inserted.

2. A floating offshore wind turbine system as described in claim 1, wherein the transport vessel coupling section has a roughly L-shaped cross section with a vertical section extending upward from the tip of the horizontal section fixed to the transport vessel main body, and the sub-floating body coupling section has a roughly L-shaped cross section with a vertical section extending downward from the tip of the horizontal section fixed to the sub-floating body.

3. A floating offshore wind turbine system according to claim 1, characterized in that the center of gravity of the floating offshore wind turbine is below the contact point between the transport vessel coupling part and the sub-floating body coupling part.

4. A floating offshore wind turbine system according to claim 1, characterized in that the sub-floating body is connected to the main floating body at a connecting portion in a manner that allows for disconnection.

5. A floating offshore wind turbine system as claimed in claim 4, characterized in that by connecting the main float and the sub-float, one of a barge-type float, a tension leg platform-type float, a semi-submersible float, and a spar-type float is formed.

6. A method for transporting a floating offshore wind turbine in a floating offshore wind turbine system as claimed in claim 4, comprising: a fitting step of fitting the transport vessel coupling part and the sub-floating body coupling part; and a transport step of transporting the floating offshore wind turbine while being supported by the transport vessel.

7. A method for transporting a floating offshore wind turbine as described in claim 6, characterized in that in the transport step, part of the buoyancy of the transport vessel is imparted to the floating offshore wind turbine via the transport vessel coupling section and the sub-floating vessel coupling section.

8. A method for transporting a floating offshore wind turbine as described in claim 6, characterized in that in the transport step, part of the buoyancy of the transport vessel is imparted to the floating offshore wind turbine via a support section that extends farther than the rear end of the transport vessel coupling section.

9. A floating offshore wind turbine that can be inserted into a main float of a floating offshore wind turbine system, comprising: blades that receive wind; a hub to which the blades are fixed; a nacelle that houses a generator that converts the rotational energy of the hub into electricity; a tower that supports the nacelle; a sub-float that supports the tower; and a sub-float coupling part that can be fitted with a transport ship coupling part, wherein when transported by a transport ship, part of the buoyancy of the transport ship is imparted to the floating offshore wind turbine.

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