Offshore Installation System and Offshore Installation Method for Floating Wind Turbines

Abstract

The present invention provides an offshore installation system and an offshore installation method for a floating wind turbine. The offshore installation system includes an installation vessel, a plurality of monopiles, a towing mechanism, a plurality of jacking devices, and a crane. The installation vessel is located in a shallow sea area and can stand on the seabed; the plurality of monopiles are vertically erected in the seabed of the shallow sea area at circumferential intervals; the plurality of monopiles enclose a containing space; the installation vessel is close to the containing space; the towing mechanism is used to tow the semi-submersible foundation of the floating wind turbine into the containing space; the plurality of jacking devices are arranged in one-to-one correspondence with the plurality of monopiles; each jacking device is located underwater and inside the corresponding monopile, and each jacking device can be lifted and lowered to lift and support the semi-submersible foundation; the crane is arranged on the installation vessel and is used to hoist the tower barrel and the wind turbine nacelle assembly of the floating wind turbine onto the semi-submersible foundation.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore installation of wind turbines, and in particular to an offshore installation system and an offshore installation method of a floating wind turbine. Background Art

[0002] With the increasing demand for renewable energy, offshore wind power has attracted more and more attention due to its advantages such as stable wind resources and long duration. The utilization and development of wind power is gradually shifting from land to sea, and is showing an accelerating development trend. However, due to the limited offshore space resources, the development of offshore wind power is gradually developing from offshore to deep sea. Among them, floating offshore wind power is an inevitable choice for future wind energy utilization.

[0003] At present, the floating foundation forms of offshore floating wind turbines are mainly divided into semi-submersible (Semi-Sub), single column (Spar) and tension leg type (TLP). Semi-submersible floating foundation is highly favored in floating wind power development due to its advantages such as wide applicable water depth range, large waterline area, good stability, low installation cost and low difficulty.

[0004] Floating wind turbines have high power and blade lengths exceeding 100 meters, which requires the tower to meet the corresponding height. The overall size and weight of the wind turbine unit also far exceed those of fixed wind turbines. The lifting weight and lifting height of the crane used to install fixed wind turbines in offshore waters are limited and cannot meet the requirements for floating wind turbine unit installation. The installation of offshore wind turbines requires high positioning accuracy, and the requirements for weather and sea conditions during operation are very stringent.

[0005] Commonly used floating wind turbine installation methods include deep-water dock installation, floating crane installation, and self-propelled self-elevating wind turbine installation ship. In the deep-water dock installation, the floating wind turbine foundation is floated in the construction base and then towed to the deep-water installation dock. The wind turbine unit and tower are installed using large lifting equipment such as crawler cranes or shore cranes. After that, the floating foundation and wind turbine integrated platform are wet-lifted to the target sea area by tugboats for platform positioning and mooring system reconnection. The disadvantage of this method is that the draft of the floating foundation and wind turbine integrated platform is very large, and the number of ports and docks that meet the operating conditions is extremely limited. If the installation dock is far away from the wind farm, the economic efficiency is greatly reduced. Therefore, this method is difficult to be widely used in the installation of floating wind turbines in China. The floating crane installation is suitable for the installation of wind turbine units with lower power. A suitable temporary installation area is selected in the offshore, and the tower and wind turbine unit are installed on the floating wind turbine foundation by the floating crane. After that, the floating wind power platform is wet-lifted as a whole to the operating sea area for installation. However, since floating cranes have poor construction stability and are extremely dependent on weather and wave conditions, it is very difficult to control the construction period; and the construction cost of large floating cranes is very high, which will greatly increase the construction and installation costs of floating wind turbines. Self-propelled self-elevating wind power installation vessels are suitable for deep-water floating wind power installation. Wind power installation vessels have the advantages of both self-elevating platforms and floating ships, and must meet the water depth requirements, crane lifting capacity and lifting height of the floating wind turbine operating area. Because the configuration requirements of self-propelled self-elevating wind power installation vessels are very high, their construction and use costs are extremely expensive, which directly affects the economic benefits of floating wind farms.

[0006] The above-mentioned installation methods of floating wind turbines are either not widely applicable due to the limitation of the water depth of the dock, or the construction is difficult and the construction period cannot be controlled, or the construction cost is too high, which affects the economic feasibility of floating wind power. Summary of the invention

[0007] The object of the present invention is to provide an offshore installation system and an offshore installation method of a floating wind turbine which are not restricted by a dock, have high installation efficiency and low construction cost, so as to solve the problems in the prior art.

[0008] In order to solve the above technical problems, the present invention provides an offshore installation system for a floating wind turbine, comprising:

[0009] The installation vessel is located in shallow waters and is able to stand on the seabed;

[0010] A plurality of monopiles are erected on the seabed of a shallow sea area at intervals along the circumferential direction; the plurality of monopiles are enclosed to form a containing space; the installation vessel is close to the containing space;

[0011] A towing mechanism, used for towing the semi-submerged foundation of the floating wind turbine into the accommodating space;

[0012] Multiple jacking devices are arranged in one-to-one correspondence with the multiple single piles; each of the jacking devices is located below the sea surface and inside the corresponding single pile, and each of the jacking devices can be lifted and lowered so that the jacking device rises to support the semi-submersible foundation;

[0013] A crane is arranged on the installation ship and is used to hoist the tower barrel and the wind turbine nacelle assembly of the floating wind turbine onto the semi-submersible foundation.

[0014] In one embodiment, the single piles are arranged on the outer sides of the columns of the semi-submersible foundation.

[0015] In one embodiment, two single piles are arranged on the outer side of the column where the tower barrel is located.

[0016] In one embodiment, the towing mechanism includes a tugboat and a winch;

[0017] The tugboat is located in the shallow sea area and is used to tow the semi-submersible foundation close to the accommodation space, so that the winch and the semi-submersible foundation are arranged on opposite sides of the accommodation space;

[0018] The winch is located at the top of the single pile and is used to tow the semi-submersible foundation close to the accommodation space into the accommodation space.

[0019] In one embodiment, the jacking device is connected to the single pile through a fixing frame, the fixing frame is sleeved on the single pile and fixedly connected to the single pile;

[0020] The jacking device includes a telescopic rod, a support plate and a driving member. The telescopic rod includes a fixed end connected to the fixing frame and a free end that moves up and down relative to the fixed end. The free end is located above the fixed end. The support plate is fixed to the free end and moves up and down with the free end. The driving member is fixed to the fixing frame and drives the free end of the telescopic rod to move up and down.

[0021] In one embodiment, the water depth of the shallow sea area is 20m to 50m.

[0022] In one embodiment, it further includes multiple fender protection structures, and the multiple fender protection structures are arranged in one-to-one correspondence with the multiple single piles;

[0023] Each of the fender protection structures is arranged at the upper part of the inner side of the corresponding single pile, and the fender protection structure has elasticity to protect the semi-submersible foundation located in the accommodation space.

[0024] In one embodiment, each of the fender protection structures includes multiple fender protection segments arranged at intervals in the vertical direction;

[0025] The material of each fender protection section is rubber.

[0026] In one embodiment, the installation vessel includes a hull and pile legs arranged at intervals along the circumference of the hull. The pile legs can be lifted and lowered relative to the hull and can be inserted into the seabed.

[0027] In one embodiment, the offshore installation system further includes a pile driving device located on the installation vessel for driving the monopiles into the seabed;

[0028] The tower barrel and the wind turbine nacelle assembly are stored on the installation vessel.

[0029] The present invention also provides an offshore installation method for a floating wind turbine, including the following steps:

[0030] Install a plurality of monopiles in the shallow sea area, arrange the plurality of monopiles at intervals along the circumference, and enclose to form a receiving space;

[0031] Install a jacking device inside each of the monopiles, and locate the jacking device below the sea surface;

[0032] Tow the semi-submersible foundation of the floating wind turbine into the receiving space;

[0033] Inject ballast water into the semi-submersible foundation to sink the semi-submersible foundation, so that the semi-submersible foundation is located above the jacking device and has a height difference from the jacking device;

[0034] Raise the jacking device so that the top of the jacking device fits against the bottom of the semi-submersible foundation to support the semi-submersible foundation;

[0035] Lift and install the pre-assembled tower barrel onto the semi-submersible foundation;

[0036] Lift and install the pre-assembled wind turbine nacelle assembly onto the tower barrel;

[0037] Discharge the ballast water in the semi-submersible foundation to make the semi-submersible foundation float upward and separate from the jacking device;

[0038] Tow the assembled semi-submersible foundation, the tower barrel and the wind turbine nacelle assembly to the working sea area of the floating wind turbine, and perform positioning and mooring system reconnection.

[0039] In one embodiment, the water depth of the shallow sea area is 20 - 50 m.

[0040] In one embodiment, the installation steps of the monopile are as follows:

[0041] Transport the monopile to the shallow sea area by an installation vessel, and insert the monopile into the seabed of the shallow sea area by a crane and a pile driving device located on the installation vessel.

[0042] In one embodiment, the towing step of the semi-submersible foundation includes:

[0043] Tow the semi-submersible foundation to near the accommodation space by a tugboat;

[0044] Drag the semi-submersible foundation into the accommodation space by a winch located on the monopile. Before entering the accommodation space, the semi-submersible foundation and the winch are respectively arranged on opposite sides of the accommodation space.

[0045] In one embodiment, when the semi-submersible foundation sinks, stop injecting ballast water when it is 0.4 - 0.6 m away from the jacking device.

[0046] In one embodiment, after the jacking device rises and contacts the semi-submersible foundation, continue to inject ballast water into the semi-submersible foundation to make the gravity of the semi-submersible foundation greater than the buoyancy it receives and thus sit firmly.

[0047] In one embodiment, in the step of discharging ballast water from the semi-submersible foundation, when the sum of the weights of the semi-submersible foundation, the tower barrel, and the wind turbine nacelle assembly is slightly less than the buoyancy, lower the jacking device to make the semi-submersible foundation float.

[0048] In one embodiment, in the pre-assembly step of the tower barrel, assemble multiple tower barrel segments located on the installation vessel to obtain the tower barrel;

[0049] In the pre-assembly step of the wind turbine nacelle assembly, assemble the wind turbine blades, the hub, and the nacelle located on the installation vessel to obtain the wind turbine nacelle assembly.

[0050] In one embodiment, after the tower barrel is hoisted onto the semi-submersible foundation, discharge the ballast water of the semi-submersible foundation outward to make the sum of the weights of the semi-submersible foundation and the tower barrel greater than the buoyancy;

[0051] After the wind turbine nacelle assembly is hoisted onto the tower barrel, discharge the ballast water of the semi-submersible foundation outward to make the sum of the weights of the semi-submersible foundation, the tower barrel, and the wind turbine nacelle assembly greater than the buoyancy.

[0052] From the above technical solutions, the advantages and positive effects of the present invention are as follows:

[0053] The offshore installation system in the present invention includes an installation vessel, multiple monopiles, a towing mechanism, multiple jacking devices, and a crane. They cooperate with each other to complete the assembly of the semi-submersible foundation, tower barrel, and wind turbine nacelle assembly in the shallow sea area, eliminating the need for assembly at port terminals and getting rid of the dependence on deep-water terminal resources, which is worthy of wide promotion. Moreover, this offshore installation system only includes one self-elevating installation vessel, requiring fewer large marine machinery and equipment, greatly saving installation resources and construction costs and reducing the installation cost.

[0054] Meanwhile, the crane of this offshore installation system is located on the installation vessel, and the semi-submersible foundation can be stably seated on the jacking devices in the accommodation space, enabling the crane and the semi-submersible foundation to be in a relatively stable state during the installation process, reducing the impact of the marine environment on the installation process, thereby reducing the installation difficulty and improving the safety and installation efficiency of the installation process.

[0055] Meanwhile, in the offshore installation method, the tower barrel and the wind turbine nacelle assembly can be pre-installed, and when hoisted onto the semi-submersible foundation, there are only two vertical butt joints, namely the vertical butt joint between the tower barrel and the semi-submersible foundation and the vertical butt joint between the wind turbine nacelle assembly and the tower barrel, shortening the time and improving the operation efficiency. Description of the Drawings

[0056] Figure 1 It is a top view schematic diagram of the offshore installation system in the present invention towing the semi-submersible foundation.

[0057] Figure 2 It is a front view schematic diagram of the offshore installation system in the present invention towing the semi-submersible foundation.

[0058] Figure 3 It is a structural schematic diagram of the semi-submersible foundation located in the accommodation space of the offshore installation system in the present invention.

[0059] Figure 4 It is a front view schematic diagram of the tower barrel and the wind turbine nacelle assembly located on the semi-submersible foundation in the present invention.

[0060] Figure 5 It is a front view schematic diagram of a partial structure of the jacking device, winch, and monopile in the present invention.

[0061] Figure 6 It is a top view schematic diagram of the jacking device and the monopile in the present invention.

[0062] Explanation of the reference numerals is as follows: 1. Offshore installation system; 11. Installation vessel; 12. Monopile; 13. Jacking device; 14. Fixed frame; 15. Tugboat; 16. Winch; 17. Fender protection block; 18. Crane;

[0063] 21. Semi-submersible foundation; 22. Tower barrel segment; 23. Wind turbine nacelle assembly;

[0064] 3. Seabed. Detailed Embodiment

[0065] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments, all of which do not depart from the scope of the present invention, and the descriptions and illustrations therein are for illustrative purposes in nature and not intended to limit the present invention.

[0066] To further illustrate the principle and structure of the present invention, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0067] The present invention provides an offshore installation system for a floating wind turbine, which is used to install the floating wind turbine. The installation efficiency of this offshore installation system is relatively high, the installation difficulty is relatively low, and the safety during the installation process is relatively high.

[0068] Among them, the floating wind turbine includes a semi-submersible foundation, a tower barrel, a wind turbine nacelle assembly, and an anchoring system. The semi-submersible foundation can float on the sea surface, and the semi-submersible foundation has a ballast tank, and the draft of the semi-submersible foundation can be adjusted by adjusting the ballast water. The semi-submersible foundation includes three columns or four columns, or other quantities, which are specifically set according to the actual situation.

[0069] The tower barrel is arranged on the semi-submersible foundation. Specifically, the tower barrel is located above one of the columns. The tower barrel includes a plurality of tower barrel segments stacked along its axial direction.

[0070] The wind turbine nacelle assembly is arranged on the tower barrel, and it specifically includes wind turbine blades, a hub, and a nacelle.

[0071] In this embodiment, the offshore installation system will be introduced by taking the floating wind turbine with a three-column semi-submersible foundation as an example.

[0072] Figure 1 The top view schematic diagram of the offshore installation system and the semi-submersible foundation in the present application is shown, Figure 2 The front view schematic diagram of the offshore installation system and the semi-submersible foundation in the present application is shown, Figure 3 The schematic diagram of the semi-submersible foundation entering the accommodation space of the offshore installation system is shown, Figure 4 The schematic diagram of the tower barrel and the wind turbine nacelle assembly installed on the semi-submersible foundation located in the accommodation space is shown, in combination with Figures 1 - 4, the offshore installation system 1 includes an installation vessel 11, a plurality of monopiles 12, a towing mechanism, a plurality of jacking devices 13, a pile driving device (not shown in the figure), and a crane 18. The offshore installation system 1 in this embodiment is located in a shallow sea area and can install the semi-submersible foundation 21, the tower barrel, and the wind turbine nacelle assembly 23 in the shallow sea area, getting rid of the dependence on deep-water wharves, thus being not restricted by wharves and worthy of being vigorously promoted. When the offshore installation system 1 is installing, both the installation vessel 11 and the semi-submersible foundation 21 are in a fixed state, reducing the installation difficulty, improving the installation efficiency and the safety during the installation process. At the same time, compared with the installation at a wharf, the offshore installation system 1 can achieve installation in the shallow sea area, shortening the distance of offshore towing, reducing the capsizing risk, and improving the safety of towing.

[0073] The shallow sea area in this application refers to the sea area with a water depth of 20m to 50m. At the same time, the wind and waves in the shallow sea area are small, and the geological conditions are good, which is suitable for pile insertion.

[0074] Furthermore, the shallow sea area can be selected to be located around the wind farm.

[0075] The installation vessel 11 is located in the shallow sea area and can stand on the seabed. Specifically, the installation vessel 11 includes a hull and pile legs arranged at intervals along the circumference of the hull. The pile legs can be lifted and lowered relative to the hull and can be inserted into the seabed. That is, the installation vessel 11 is a jack-up vessel.

[0076] The tower barrel and the wind turbine nacelle assembly 23 can be stored on the deck of the hull. The monopiles 12 can also be stored on the deck of the hull.

[0077] In this embodiment, the monopiles 12 are first stored on the hull. After the monopiles 12 are installed, the tower barrel and the wind turbine nacelle assembly 23 are transported by a transport ship. In other embodiments, the tower barrel and the wind turbine nacelle assembly 23 can be stored on the hull, and the monopiles 12 are transported by a transport ship.

[0078] A plurality of monopiles 12 are vertically erected in the seabed of the shallow sea area at intervals along the circumference. The plurality of monopiles 12 enclose a receiving space for receiving the semi-submersible foundation 21. The installation vessel 11 is close to the receiving space.

[0079] In this embodiment, the number of monopiles 12 is four. Two of the monopiles 12 are arranged in one-to-one correspondence with the two columns of the semi-submersible foundation 21. The other two monopiles 12 are arranged in pairs and are correspondingly arranged with the remaining one column of the semi-submersible foundation 21. The two monopiles 12 arranged in pairs and corresponding to one column are close to the installation vessel 11.

[0080] That is, when the semi-submersible foundation 21 is located in the receiving space, the two monopiles 12 arranged in pairs are simultaneously located outside one of the columns, and the other two monopiles 12 are arranged in one-to-one correspondence with the other two columns of the semi-submersible foundation 21.

[0081] The offshore installation system 1 further includes a plurality of fender protection structures. The plurality of fender protection structures are arranged in one-to-one correspondence with the plurality of monopiles 12.

[0082] Figure 5 The top view schematic diagram of the monopile, the jacking equipment, the fixing frame and the fender protection block is shown. Figure 6 The front view schematic diagram of the monopile, the jacking equipment, the fixing frame, the winch and the fender protection block is shown. Combining Figure 5 and Figure 6 , each fender protection structure is arranged at the upper part of the inner side of the corresponding monopile 12, and the fender protection structure is elastic, playing a buffering role to avoid collision damage to the structure of the semi-submersible foundation 21, so as to protect the semi-submersible foundation 21 entering the accommodation space. Among them, the inner side and the outer side are referenced based on the fixed state of the plurality of monopiles 12. The side facing the accommodation space enclosed by the plurality of monopiles 12 is the inner side, and the opposite side is the outer side.

[0083] Each fender protection structure includes a plurality of fender protection blocks 17. Among them, a plurality of fender protection blocks 17 are arranged at intervals in the vertical direction, and a plurality of fender protection blocks 17 are arranged at intervals along the circumferential direction of the monopile 12. In this embodiment, there are three layers arranged at intervals in the vertical direction, and three fender protection blocks 17 are arranged at intervals in the circumferential direction in each layer. Specifically, the material of each fender protection block 17 is rubber.

[0084] The towing mechanism is used to tow the semi-submersible foundation 21 of the floating wind turbine into the accommodation space. Specifically, the towing mechanism includes a tugboat 15 and a winch 16.

[0085] Among them, the tugboat 15 is located in the shallow sea area and is used to tow the semi-submersible foundation 21 to be close to the accommodation space, so that the winch 16 and the semi-submersible foundation 21 are arranged on opposite sides of the accommodation space.

[0086] In this embodiment, the number of tugboats 15 is two, and the two tugboats 15 are arranged on both sides of the moving direction of the semi-submersible foundation 21.

[0087] The winch 16 is located at the top of the monopile 12 and is used to tow the semi-submersible foundation 21 close to the accommodation space into the accommodation space. Specifically, the winch 16 is located at the top of the monopile 12 close to the installation ship 11, that is, the tugboat 15 tows the semi-submersible foundation 21 to the opposite side relative to the installation ship 11.

[0088] Through the cooperation of the tugboat 15 and the winch 16, the semi-submersible foundation 21 is towed into the accommodation space.

[0089] A plurality of jacking devices 13 are arranged in one-to-one correspondence with the plurality of monopiles 12. Each jacking device 13 is located below the sea surface and inside the corresponding monopile 12, and each jacking device 13 can be lifted and lowered so that the jacking device 13 rises to support the semi-submersible foundation 21.

[0090] Continue to refer toFigure 5 and Figure 6 The jacking device 13 is connected to the single pile 12 through the fixing frame 14. The fixing frame 14 is sleeved on the single pile 12 and fixedly connected to the single pile 12. The fixing frame 14 is provided with a through hole for sleeving on the outer periphery of the single pile 12.

[0091] The fixing frame 14 includes a fixing portion protruding inwards from the single pile 12. The fixing portion is plate-shaped and extends horizontally.

[0092] Specifically, the jacking device 13 includes a telescopic rod, a support plate, and a driving member. The telescopic rod extends vertically and specifically includes a fixed end and a free end that moves up and down relative to the fixed end. The fixed end is fixedly connected to the fixing portion, and the free end is located above the fixed end.

[0093] In this embodiment, each jacking device 13 includes four telescopic rods. The four telescopic rods are arranged in a 2×2 array.

[0094] The support plate is fixed to the free end and moves up and down with the free end. In this embodiment, the number of support plates is two, and each support plate corresponds to two telescopic rods. In other embodiments, it may be that four telescopic rods are commonly connected to a support plate, or four telescopic rods correspond to four support plates one by one.

[0095] The driving member is fixed to the fixing frame 14 and drives the free end of the telescopic rod to move up and down. In this embodiment, the driving member is an oil cylinder.

[0096] That is, the semi-submersible foundation 21 entering the accommodation space is kept in a relatively fixed state through the buffering and support of the jacking device 13.

[0097] The crane 18 is arranged on the installation vessel 11 and is used to hoist and install the tower barrel and the wind turbine nacelle assembly 23 of the floating wind turbine onto the semi-submersible foundation 21. In this embodiment, the lifting capacity of the crane 18 is more than 2000t.

[0098] The pile driving equipment is located on the installation vessel 11 and is used to drive the single pile 12 into the seabed. Specifically, the pile driving equipment is located on the deck of the installation vessel 11. Through the hoisting of the crane 18 and the pile driving of the pile driving equipment, the single pile 12 is inserted into the seabed.

[0099] The offshore installation system 1 in this embodiment can complete the assembly of the semi-submersible foundation 21, the tower barrel, and the wind turbine nacelle assembly 23 in the shallow sea area, without the need for assembly at the port terminal, getting rid of the dependence on deep-water terminal resources, and is worthy of wide promotion. And the offshore installation system 1 only includes one self-elevating installation vessel 11, requiring fewer large ship machinery and equipment, greatly saving installation resources and construction costs, and reducing the installation cost.

[0100] Meanwhile, the crane 18 of the offshore installation system 1 is located on the installation vessel 11, and the semi-submersible foundation 21 can be stably seated on the jacking device 13 within the accommodation space, such that during the installation process, the crane 18 and the semi-submersible foundation 21 are in a relatively stable state, reducing the impact of the marine environment on the installation process, thereby reducing the installation difficulty and improving the safety and installation efficiency of the installation process.

[0101] The offshore installation system 1 can be reused, that is, after installing one floating wind turbine and towing it away, the installation of the next floating wind turbine can be carried out, reducing the installation time of multiple floating wind turbines and shortening the construction period of the floating wind farm.

[0102] Furthermore, the offshore installation system 1 can be selected in the shallow sea area around the wind farm. Compared with the dock installation method, the distance of offshore towing is shortened, and the risk of capsizing of the semi-submersible foundation 21, the tower barrel and the wind turbine nacelle assembly 23 with a relatively high center of gravity during towing is reduced, improving the safety of towing.

[0103] The present invention also provides an offshore installation method for a floating wind turbine, comprising the following steps:

[0104] S1. Install a plurality of monopiles 12 in the shallow sea area, such that the plurality of monopiles 12 are arranged at circumferential intervals and enclose to form an accommodation space.

[0105] Among them, the water depth of the shallow sea area is 20 - 50 m. Meanwhile, the wind and waves in this shallow sea area are small, and the geological conditions are good, which is suitable for pile driving.

[0106] Specifically, the installation steps of the monopile 12 are as follows:

[0107] Transport the monopile 12 to the shallow sea area through the installation vessel 11, and insert the monopile 12 into the seabed of the shallow sea area through the crane 18 and the pile driving equipment located on the installation vessel 11.

[0108] Among them, the number and driving positions of the monopiles 12, the height of the monopiles 12, and the driving depth of the monopiles 12 are determined according to the geological conditions, hydrological environment conditions of the shallow sea area, the form, size, weight and draft of the semi-submersible foundation 21 of the floating wind turbine, and other information.

[0109] That is, before installing the monopiles 12, it further includes step S0: selection of the shallow sea area, and design of the construction plan according to the conditions of the shallow sea area and various information of the semi-submersible foundation 21. S2. Install a jacking device 13 inside each monopile 12, such that the jacking device 13 is located below the sea surface.

[0110] The installation height of the jacking device 13 is determined according to the geological conditions, hydrological environment conditions of the shallow sea area, the form, size, weight and draft of the semi-submersible foundation 21 of the floating wind turbine, and other data.

[0111] S3. Tow the semi-submersible foundation 21 of the floating wind turbine into the accommodation space.

[0112] Specifically, the towing steps of the semi-submersible foundation 21 include:

[0113] S31. Tow the semi-submersible foundation 21 close to the accommodation space by the tugboat 15.

[0114] In this embodiment, at this time, the semi-submersible foundation 21 and the installation ship 11 are respectively located on opposite sides of the accommodation space.

[0115] The semi-submersible foundation 21 is initially located at the construction base wharf and is towed by the tugboat 15.

[0116] S32. Pull the semi-submersible foundation 21 into the accommodation space by the winch 16 located on the monopile 12. Among them, before entering the accommodation space, the semi-submersible foundation 21 and the winch 16 are respectively located on opposite sides of the accommodation space.

[0117] Among them, the installation of the winch 16 can be carried out after the monopile 12 is inserted. That is, after the monopile 12 is inserted, the winch 16 is cross-lifted to the top of the monopile 12 by the crane 18 and installed.

[0118] S4. Inject ballast water into the semi-submersible foundation 21 to make the semi-submersible foundation 21 sink, so that the semi-submersible foundation 21 is located above the lifting device 13 and there is a height difference between the semi-submersible foundation 21 and the lifting device 13.

[0119] When the semi-submersible foundation 21 sinks, stop injecting ballast water when it is 0.4 - 0.6 m away from the lifting device 13. That is, the height difference between the semi-submersible foundation 21 and the lifting device 13 is 0.4 - 0.6 m.

[0120] S5. Raise the lifting device 13 so that the top of the lifting device 13 fits against the bottom of the semi-submersible foundation 21 to support the semi-submersible foundation 21.

[0121] After the lifting device 13 is raised and contacts the semi-submersible foundation 21, continue to inject ballast water into the semi-submersible foundation 21 so that the gravity of the semi-submersible foundation 21 is greater than the buoyancy it receives and it sits firmly.

[0122] Specifically, after the driving part of the lifting device 13 receives the signal, it drives the telescopic rod to rise, thereby driving the support plate to rise, making the support plate contact the bottom of the semi-submersible foundation 21, lifting the semi-submersible foundation 21, and preventing the heaving motion of the semi-submersible foundation 21 from hitting the lifting device 13.

[0123] S6. Hoist and install the pre-assembled tower barrel onto the semi-submersible foundation 21.

[0124] In the pre-assembly steps of the tower barrel, multiple tower barrel segments 22 located on the installation vessel 11 are assembled to obtain the tower barrel. This pre-assembly process is carried out on the installation vessel 11.

[0125] The tower barrel segments 22 are assembled in the axial order from bottom to top.

[0126] Among them, the tower barrel segments 22 can be transported to the installation vessel 11 by a transport ship. The pre-assembly of the tower barrel can be carried out simultaneously with the towing and sinking of the semi-submersible foundation 21, etc.

[0127] Further, after the tower barrel is hoisted onto the semi-submersible foundation 21, the ballast water of the semi-submersible foundation 21 is discharged outward, so that the sum of the weights of the semi-submersible foundation 21 and the tower barrel is greater than the buoyancy. That is, after the tower barrel is installed on the semi-submersible foundation 21, the weight of the tower barrel is added to the semi-submersible foundation 21, making the gravity borne by the semi-submersible foundation 21 much greater than the buoyancy. By discharging the ballast water, while always keeping the weight greater than the buoyancy and stable, discharging a certain amount of ballast water reduces the load on the monopile 12.

[0128] Among them, when discharging the ballast water, a preset scheme is selected for discharging in multiple compartments of the semi-submersible foundation 21. This preset scheme is designed based on the weight of the tower barrel and the compartment conditions of the semi-submersible foundation 21 to ensure that the ballast water discharge of the semi-submersible foundation 21 is symmetric, thereby ensuring the stability of the semi-submersible foundation 21.

[0129] S7. Hoist and install the pre-assembled wind turbine nacelle assembly 23 onto the tower barrel.

[0130] In the pre-assembly steps of the wind turbine nacelle assembly 23, the wind turbine blades, hub and nacelle located on the installation vessel 11 are assembled to obtain the wind turbine nacelle assembly 23. This pre-assembly process is carried out on the installation vessel 11.

[0131] Among them, the wind turbine blades, hub and nacelle can be transported to the installation vessel 11 by a transport ship. The pre-assembly of the wind turbine nacelle assembly 23 can also be carried out simultaneously with the towing and sinking of the semi-submersible foundation 21, etc.

[0132] Further, after the wind turbine nacelle assembly 23 is hoisted onto the tower barrel, the ballast water of the semi-submersible foundation 21 is discharged outward, so that the sum of the weights of the semi-submersible foundation 21, the tower barrel and the wind turbine nacelle assembly 23 is greater than the buoyancy, ensuring the stability of the semi-submersible foundation 21 and reducing the load borne by the monopile 12.

[0133] Similarly, when discharging the ballast water, a preset scheme is selected for discharging in multiple compartments of the semi-submersible foundation 21. This preset scheme is designed based on the weight of the tower barrel and the compartment conditions of the semi-submersible foundation 21 to ensure that the ballast water discharge of the semi-submersible foundation 21 is symmetric, thereby ensuring the stability of the semi-submersible foundation 21.

[0134] S8. Drain the ballast water inside the semi-submersible foundation 21 to make the semi-submersible foundation 21 float upward and disengage from the jacking device 13.

[0135] After the tower barrel and the wind turbine nacelle assembly 23 are installed on the semi-submersible foundation 21, they need to be towed to the destination. Therefore, it is necessary to make the semi-submersible foundation 21 disengage from the jacking device 13. Specifically, the semi-submersible foundation 21 is made to float by discharging ballast water.

[0136] In the step of discharging the ballast water from the semi-submersible foundation 21, when the sum of the weights of the semi-submersible foundation 21, the tower barrel and the wind turbine nacelle assembly 23 is slightly less than the buoyancy, lower the jacking device 13 to make the semi-submersible foundation 21 float. That is, when the buoyancy is greater than the gravity, the semi-submersible foundation 21 rises upward, and the semi-submersible foundation 21 disengages from the jacking device 13.

[0137] S9. Tow the assembled semi-submersible foundation 21, the tower barrel and the wind turbine nacelle assembly 23 to the working sea area of the floating wind turbine, and perform positioning and mooring system reconnection.

[0138] The semi-submersible foundation 21 disengaged from the jacking device 13 can be transported to the working sea area by wet towing. After arriving at the working sea area, perform positioning and then perform mooring system reconnection, that is, complete the installation of a floating wind turbine.

[0139] After the upper semi-submersible foundation 21, the tower barrel and the wind turbine nacelle assembly 23 are towed away from the installation system, the installation of the next floating wind turbine can be carried out. Specifically, this offshore installation method can complete the installation of a floating wind turbine in 3 to 5 days.

[0140] This offshore installation method operates in shallow sea areas, getting rid of the dependence of floating wind turbines on deep-water wharf resources. Moreover, during the installation process, the crane 18 and the semi-submersible foundation 21 are in a relatively stable state during installation, reducing the installation difficulty, improving the safety and installation efficiency of the installation process. And this offshore installation method mainly relies on a self-elevating installation vessel 11 suitable for operating in shallow sea areas, greatly saving installation resources and reducing installation costs.

[0141] At the same time, in this offshore installation method, the tower barrel and the wind turbine nacelle assembly 23 can be pre-installed. When hoisted onto the semi-submersible foundation 21, there are only two vertical butt joints, namely the vertical butt joint between the tower barrel and the semi-submersible foundation 21 and the vertical butt joint between the wind turbine nacelle assembly 23 and the tower barrel, shortening the time and improving the operation efficiency.

[0142] As can be seen from the above technical solutions, the advantages and positive effects of the present invention are as follows:

[0143] The offshore installation system in the present invention includes an installation vessel, multiple monopiles, a towing mechanism, multiple jacking devices, and a crane. They cooperate with each other to complete the assembly of the semi-submersible foundation, tower barrel, and wind turbine nacelle assembly in the shallow sea area, eliminating the need for assembly at port terminals and getting rid of the dependence on deep-water terminal resources, which is worthy of wide promotion. Moreover, the offshore installation system only includes one self-elevating installation vessel, requiring fewer large-scale marine machinery and equipment, greatly saving installation resources and construction costs and reducing the installation cost.

[0144] Meanwhile, the crane of the offshore installation system is located on the installation vessel, and the semi-submersible foundation can be stably seated on the jacking devices in the accommodation space, enabling the crane and the semi-submersible foundation to be in a relatively stable state during the installation process, reducing the impact of the marine environment on the installation process, thereby reducing the installation difficulty and improving the safety and installation efficiency of the installation process.

[0145] Meanwhile, in the offshore installation method, the tower barrel and the wind turbine nacelle assembly can be pre-installed, and when hoisted onto the semi-submersible foundation, there are only two vertical butt joints, namely the vertical butt joint between the tower barrel and the semi-submersible foundation and the vertical butt joint between the wind turbine nacelle assembly and the tower barrel, shortening the time and improving the operation efficiency.

[0146] Although the present invention has been described with reference to several exemplary embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above-described embodiments are not limited to any of the foregoing details, but should be broadly construed within the spirit and scope defined by the appended claims. Therefore, all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. An offshore installation method for a floating wind turbine, characterized in that, Including the following steps: Install multiple single piles in the shallow sea area, arrange the multiple single piles at circumferential intervals, and enclose to form a receiving space; Install a jacking device inside each of the single piles, and locate the jacking device below the sea surface; Tow the semi-submersible foundation of the floating wind turbine to the inside of the receiving space; Inject ballast water into the semi-submersible foundation to sink the semi-submersible foundation, so that the semi-submersible foundation is located above the jacking device and has a height difference from the jacking device; Raise the jacking device so that the top of the jacking device fits against the bottom of the semi-submersible foundation to support the semi-submersible foundation; Lift and install the pre-assembled tower barrel onto the semi-submersible foundation; Lift and install the pre-assembled wind turbine nacelle assembly onto the tower barrel; Discharge the ballast water in the semi-submersible foundation to make the semi-submersible foundation float upward and separate from the jacking device; Tow the assembled semi-submersible foundation, the tower barrel and the wind turbine nacelle assembly to the working sea area of the floating wind turbine, and perform positioning and mooring system reconnection.

2. The offshore installation method according to claim 1, characterized in that The water depth of the shallow sea area is 20 - 50 m.

3. The offshore installation method according to claim 1, characterized in that, The installation steps of the single pile are as follows: Transport the single pile to the shallow sea area by an installation vessel, and insert the single pile into the seabed of the shallow sea area through a crane and a pile driving device located on the installation vessel.

4. The offshore installation method according to claim 1, characterized in that, The towing steps of the semi-submersible foundation include: Tow the semi-submersible foundation to be close to the receiving space by a tugboat; Drag the semi-submersible foundation into the receiving space by a winch located on the single pile. Before entering the receiving space, the semi-submersible foundation and the winch are respectively arranged on opposite sides of the receiving space.

5. The offshore installation method according to claim 1, characterized in that, When the semi-submersible foundation sinks, stop injecting ballast water when it is 0.4 - 0.6 m away from the jacking device.

6. The offshore installation method according to claim 1, characterized in that, After the jacking device rises and contacts the semi-submersible foundation, continue to inject ballast water into the semi-submersible foundation to make the gravity of the semi-submersible foundation greater than the buoyancy it receives and thus sit firmly.

7. The offshore installation method according to claim 1, characterized in that, In the step of discharging the ballast water of the semi-submersible foundation, when the sum of the weights of the semi-submersible foundation, the tower barrel and the wind turbine nacelle assembly is slightly less than the buoyancy, lower the jacking device to make the semi-submersible foundation float.

8. The offshore installation method according to claim 3, characterized in that, In the pre-assembly step of the tower barrel, assemble multiple tower barrel segments located on the installation vessel to obtain the tower barrel; In the pre-assembly step of the wind turbine nacelle assembly, assemble the fan blades, the hub and the nacelle located on the installation vessel to obtain the wind turbine nacelle assembly.

9. The offshore installation method according to claim 1, characterized in that, After the tower barrel is lifted onto the semi-submersible foundation, discharge the ballast water of the semi-submersible foundation outward to make the sum of the weights of the semi-submersible foundation and the tower barrel greater than the buoyancy; After the wind turbine nacelle assembly is lifted onto the tower barrel, discharge the ballast water of the semi-submersible foundation outward to make the sum of the weights of the semi-submersible foundation, the tower barrel and the wind turbine nacelle assembly greater than the buoyancy.

10. An offshore installation system for the floating wind turbine installation method according to any one of claims 1 to 9, characterized in that, The offshore installation system includes: An installation vessel, located in the shallow sea area and capable of standing on the seabed; Multiple single piles, vertically erected in the seabed of the shallow sea area at circumferential intervals; the multiple single piles enclose to form a receiving space; the installation vessel is close to the receiving space; A towing mechanism for towing the semi-submersible foundation of the floating wind turbine into the accommodation space; A plurality of jacking devices, which are arranged in one-to-one correspondence with the plurality of monopiles; each of the jacking devices is located under the sea surface and inside the corresponding monopile, and each of the jacking devices can be lifted and lowered to lift and support the semi-submersible foundation; A crane, which is arranged on the installation ship and is used for hoisting the tower barrel and the wind turbine nacelle assembly of the floating wind turbine onto the semi-submersible foundation.

11. The marine installation system according to claim 10, wherein Monopiles are arranged on the outer sides of the columns of the semi-submersible foundation.

12. The offshore installation system according to claim 11, wherein, Two monopiles are arranged on the outer side of the column where the tower barrel is located.

13. The offshore installation system according to claim 10, characterized in that, The towing mechanism includes a tugboat and a winch; The tugboat is located in the shallow sea area and is used for towing the semi-submersible foundation to be close to the accommodation space, so that the winch and the semi-submersible foundation are respectively arranged on opposite sides of the accommodation space; The winch is located on the top of the monopile and is used for towing the semi-submersible foundation close to the accommodation space into the accommodation space.

14. The offshore installation system according to claim 10, wherein The jacking device is connected to the monopile through a fixing frame, and the fixing frame is sleeved on the monopile and fixedly connected to the monopile; The jacking device includes a telescopic rod, a support plate and a driving member. The telescopic rod includes a fixed end connected to the fixing frame and a free end that moves up and down relative to the fixed end. The free end is located above the fixed end. The support plate is fixed on the free end and moves up and down with the free end. The driving member is fixed on the fixing frame and drives the free end of the telescopic rod to move up and down.

15. The offshore installation system according to claim 10, characterized in that, The water depth of the shallow sea area is 20m to 50m.

16. The offshore installation system according to claim 10, wherein It further includes a plurality of fender protection structures, and the plurality of fender protection structures are arranged in one-to-one correspondence with the plurality of monopiles; Each of the fender protection structures is arranged at the upper part inside the corresponding monopile, and the fender protection structure has elasticity to protect the semi-submersible foundation located in the accommodation space.

17. The offshore installation system according to claim 16, characterized in that, Each of the fender protection structures includes a plurality of fender protection segments arranged at intervals in the vertical direction; The material of each of the fender protection segments is rubber.

18. The marine installation system according to claim 10, characterized in that, The installation ship includes a hull and pile legs arranged at intervals along the circumference of the hull. The pile legs can move up and down relative to the hull and can be inserted into the seabed.

19. The marine installation system according to claim 10, wherein, The offshore installation system further includes a pile driving device located on the installation ship for driving the monopiles into the seabed; The tower barrel and the wind turbine nacelle assembly are stored on the installation ship.

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