Load reduction device for floating wind turbine mooring lines and method of installation thereof

Abstract

The application discloses a load reducing device for a floating wind turbine mooring line and a mounting method thereof. The device comprises a float, a counterweight and a wing plate. The float and the counterweight are used to reduce the tension component of the mooring line and play a damping load reducing role. The wing plate is used to rotate the float and the counterweight block, convert the tension of the mooring line into a non-collinear load, and thus slow down the impact of instantaneous load. The mounting of the load reducing device comprises two parts of assembly of the device itself and hoisting connection of the device and the floating wind turbine. The load reducing device has the advantages of simple structure, high construction and mounting efficiency, solves the design problems of excessive load of the floating wind turbine mooring line and high cost, is widely applicable, efficient and reliable, and is favorable for development of large-scale and commercial offshore floating wind turbines.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of offshore wind power generation, and particularly relates to a load reduction device for a floating wind turbine mooring line and a mounting method thereof. BACKGROUND

[0002] Among numerous new energy industries, offshore wind power is favored due to large reserves, no occupation of arable land, and small environmental noise pollution. Offshore wind turbines have various foundation forms. In near-sea areas, offshore wind power is mainly fixed. However, deep sea has better wind resources and less environmental impact. Floating foundation has better economic and technical advantages. Large-scale and deep-sea offshore wind turbines are the development direction of future offshore wind power.

[0003] During the service period of offshore floating wind turbines, they are subjected to environmental loads such as wind, wave, and flow. In order to meet the requirements of on-site operation and survival, their movement range needs to be limited through their mooring system. Unlike most European and American countries, typhoons are extremely extreme and frequent in China's coastal areas. After the large-scale of offshore floating wind turbines, they will face more extreme environmental loads. The load bearing and coupled dynamics of the mooring system will be more prominent. Therefore, the development of efficient and reliable load reduction devices for floating wind turbine mooring lines will be the key to the optimization design and operation of large-scale offshore wind turbines. SUMMARY

[0004] In view of the existing problems in the operation process of the existing floating wind turbine, the application provides a load reduction device for a floating wind turbine mooring line and a mounting method thereof, which can effectively realize the tension level of the mooring line of the offshore wind turbine under normal operating conditions and extreme conditions.

[0005] A load reduction device for a floating wind turbine mooring line, the device comprising a float, a center weight block, a suspended weight block, and two wing plates.

[0006] The lower end of the float is coaxially fixedly connected with the center weight block through a connecting piece, is a detachable structure, constitutes a main body, and the top of the float is provided with lifting lugs for overall lifting of the device.

[0007] The suspended weight block is coaxially connected with the center weight block through a connecting mooring chain.

[0008] The wing plate is an open "door" type steel plate, the two ends of the opening, i.e., the two ends of the bottom of the "door", are connected with the main body through a hinge respectively, the two hinges are symmetrical about the central axis of the main body and the connecting line of the two hinges passes through the central axis, the installation heights of the two wing plates on the main body are different and the directions of the two wing plates are opposite, a first shackle is installed at the top center of the wing plate for connection with a reserved mooring chain, and a second shackle is arranged at the other end of the reserved mooring chain for connecting the entire device with the mooring line of the original floating wind turbine.

[0009] Further, the shape of the center weight block and the suspension type weight block and the weight can be determined according to the actual situation on site, for adjusting the gravity center position of the whole load reduction device.

[0010] Further, the damping wings are square damping wings, and three square damping wings are fixed on the circumference of the upper section of the buoy to follow the movement of the buoy in seawater and provide movement damping.

[0011] Further, the buoy is a steel cylinder filled with foaming material, the center weight block and the suspension type weight block are made of high-density concrete, the shape and diameter of the center weight block are consistent with the buoy, the suspension type weight block is a circular truncated cone, and a lifting lug is reserved above the suspension type weight block and connected to the center weight block through a connecting mooring chain.

[0012] Further, a circular heaving plate is coaxially fixed and installed at the bottom of the center weight block, and the circular heaving plate is a steel circular thin plate, which can play a wave cutting role, and the suspension type weight block is connected to the center of the circular heaving plate through a connecting mooring chain.

[0013] Further, the two wings are arranged on both sides of the main body, the hinge of the left wing is connected to the buoy, and the hinge of the right wing is connected to the center weight block, the wings can rotate up and down with the hinges, and an opening is reserved at the top of the wings for hoisting the wings.

[0014] The installation method of the load reduction device for the floating wind turbine mooring line is as follows:

[0015] Step 1, connect the buoy and the center weight block to form a main body, or connect the center weight block and the circular heaving plate, install the hinge, connect the wing to the main body, connect the suspension type weight block to the center weight block or the circular heaving plate through a connecting mooring chain, install the wing top shackle, connect the reserved mooring chain to the wing, and complete the assembly of the load reduction device itself.

[0016] Step 2, the crane lifts the load reduction device through the traction rope and the lifting lug at the top of the device, adjusts the angle and direction of the damping wing during lifting and placing, so as to ensure that the device is placed vertically, until the device is placed below the sea level, the mooring line of the floating wind turbine is divided into upper and lower mooring lines, the two are connected by shackles and two reserved mooring chains of the load reduction device, and the whole mooring chain is pre-tensioned by a winch, to complete the installation of the load reduction device and the whole floating wind turbine.

[0017] Step 3, when the floating wind turbine is in normal working condition of the marine environment, the wind and wave current load will act on it, the mooring line is subjected to tension, the reserved mooring chain is pulled, and the load reduction device is moved; when the mooring line load is transmitted to the load reduction device, the wing plate is first rotated, and the floating cylinder is simultaneously rotated; due to the existence of the wing plate, the upper mooring line and the lower mooring line of the floating wind turbine are not collinear, the load reduction device is subjected to torque, and then rotation occurs; the rotation process of the load reduction device makes the tension of the upper mooring line buffered for a certain time before being transmitted to the lower mooring line, so that the effect of the impact tension of the mooring line in the extreme environment is effectively reduced; when the tension of the mooring line is too large, the load reduction device rotates greatly or even reaches the overturning state; at this time, due to the existence of the floating cylinder, the mooring line will be subjected to the action of the buoyancy of the floating cylinder, thereby effectively reducing the vertical tension component of the mooring line.

[0018] In the rotation process of the load reduction device, the square damping wing plate on the floating cylinder and the circular heaving plate below the center weight block fully interact with the surrounding seawater, change the change of the surrounding seawater flow field, and play a damping dissipation role on the tension impulse transmitted to the load reduction device, thereby further reducing the tension load borne by the lower mooring line.

[0019] The present application has the following beneficial effects:

[0020] (1) The load buffering mechanism is embedded in the traditional floating wind turbine mooring line, which can effectively share the load borne by the mooring line in normal working condition; in extreme working condition, the instantaneous impact tension of the mooring line can also be effectively reduced.

[0021] (2) The effects of the traditional marine structures such as the floating cylinder, the sinker and the heaving plate in the mooring system are comprehensively considered, the installation is convenient, the cost is low, and the present application is suitable for commercialization and wide promotion of offshore wind power. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a specific example of the elevation view of the overall structure of the present application.

[0023] Figure 2 It is a specific example of the top view of the wing plate structure of the present application.

[0024] Figure 3 It is a specific example of the front view of the working principle of the present application.

[0025] Figure 4 It is a global schematic diagram of the installation of the offshore wind farm of the present application.

[0026] In the figure: 1 is a buoy, 2 is a center weight block, 3 is a suspended weight block, 4 is a connecting bolt, 4a is an upper connecting bolt, 4b is a lower connecting bolt, 5a is a first lifting lug, 5b is a second lifting lug, 5c is a third lifting lug, 6 is a damping wing plate, 7 is a circular heaving plate, 8a is a connecting mooring chain, 8b is a reserved mooring chain, 9 is a wing plate, 10a is a first shackle, 10b is a second shackle, 11 is a hinge, 12 is a rectangular opening, 13 is a floating wind turbine, 14a is an upper anchoring line, 14b is a lower anchoring line. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be further described below in combination with embodiments and drawings:

[0028] The load reduction device for the anchoring line of the floating wind turbine of the present application comprises three core functional components of a buoy, a weight and a wing plate; wherein the buoy and the weight are used to reduce the tension component of the anchoring line and play a damping load reduction role, and the wing plate is used to rotate the buoy and the weight block to convert the anchoring line tension into a non-collinear load, thereby reducing the impact of instantaneous load.

[0029] Specifically, a load reduction device for the anchoring line of the floating wind turbine comprises a buoy 1 and a center weight block 2, a suspended weight block 3 and a wing plate 9, the buoy 1 and the center weight block 2 constitute a main body, the central axes of the buoy 1 and the center weight block 2 and the suspended weight block 3 are collinear, and all connection points of the wing plate 9 with the main body are coplanar with the central axes.

[0030] According to a specific embodiment of the present application, the buoy 1 is made of foam material and is used to provide overall buoyancy of the entire device. The upper connecting bolts 4a are uniformly arranged on the outer side of the lower part of the buoy 1 in the circumferential direction to connect the buoy 1 with the center weight block 2. The first lifting lug 5a is reserved on the top of the buoy 1 for overall hoisting of the device. Three square damping wing plates 6 are symmetrically arranged around the upper part of the buoy 1, which are made of steel and are welded together with the buoy 1. The damping wing plates 6 can rotate and move in the sea water to adjust the buoyancy and resistance received, so as to change the up-and-down floating and turning of the buoy 1; during installation, the damping wing plates 6 also play a role in positioning and stabilizing the overall device, which facilitates overall hoisting of the device.

[0031] The center weight 2 is connected to the buoy 1 by the upper connecting bolt 4a, and is designed as a detachable structure. When the overall device is recycled, the upper connecting bolt 4a can be separated from the buoy 1, which plays a convenient transportation role. The center weight 2 can be made of concrete, and the shape and diameter are consistent with the buoy 1, and the height is about one fourth of the buoy 1. By adjusting the density and height of the center weight 2, the center of gravity of the overall device can be changed. In addition, in a specific embodiment of the present application, the bottom of the center weight 2 can be fixedly installed with a circular heaving plate 7, which is a steel circular thin plate connected to the bottom of the center weight 2 by the lower connecting bolt 4b. The circular heaving plate 7 can play a wave cutting role. When the reserved mooring chain 8b is stable, it can move the center of gravity of the buoy 1 downward, thereby improving the stability of the buoy 1; when the reserved mooring chain 8b oscillates to drive the overall device to shake, it can slow down the overall rotation rate of the device, thereby prolonging the load response time of the reserved mooring chain 8b. The bottom of the center weight 2 and the circular heaving plate 7 is provided with a second lifting lug 5b for connecting the lower connecting mooring chain 8a.

[0032] The third lifting lug 5c is reserved above the bottom of the suspended weight 3, which is connected to the center weight 2 (when the circular heaving plate 7 exists, it is connected to the circular heaving plate 7) by the connecting mooring chain 8a. The suspended weight 3 can also be made of concrete, and the shape can be a circular table, and the diameter and height can be determined according to the actual situation on site, which is used to adjust the center of gravity of the overall load reduction device.

[0033] Each load reduction device is matched with two wings 9. The wings 9 are open "door" type structures made of steel plates. The top center of the wing 9 is provided with a small opening for installing a first shackle 10a, and the wing 9 is connected to the reserved mooring chain 8b by the first shackle 10a. The end of the reserved mooring chain 8b is also provided with a second shackle 10b for connecting the entire device to the anchor line of the original floating wind turbine 13. The lower part of each wing 9 is provided with two hinges 11 on both sides, wherein the hinge 11 of the left wing 9 is connected to the buoy 1; the hinge 11 of the right wing 9 is connected to the center weight 2, and the connection point of the hinge 11 is located in the same plane as the center axis of the buoy 1 and the center weight 2. The wing 9 can rotate up and down with the hinge. The top of the wing 9 is also provided with a rectangular opening 12 for hoisting the wing 9.

[0034] According to a specific embodiment of the present application, as shown in Figures 1-4 The specific implementation steps of the present application are as follows:

[0035] Step 1, as shown in Figures 1-3As shown, the upper connecting bolt 4a and the lower connecting bolt 4b are respectively tightened to connect the buoy 1 and the center weight 2, and the center weight 2 and the circular heave plate 7. The hinge 11 is installed to connect the wing plate 9 with the buoy 1 and the center weight 2; the connecting mooring chain 8a is installed between the circular heave plate 7 and the suspended weight 3 by using a crane. The wing plate 9 top shackle is installed to connect the reserved mooring chain 8b with the wing plate 9, and the assembly of the load reduction device itself is completed.

[0036] Step 2, the crane lifts the load reduction device through the first lifting lug 5a by the traction rope. When the load reduction device is lowered, the angle and direction of the square damping wing plate 6 are adjusted to ensure that the device is lowered vertically until the device is lowered below sea level. Figure 4 As shown, the original anchor line of the floating wind turbine 13 is divided into two sections, the upper anchor line 14a and the lower anchor line 14b. The two sections are connected by the second shackle 10b and the reserved mooring chain 8b of the load reduction device, respectively, to complete the overall installation of the load reduction device and the floating wind turbine 13.

[0037] Step 3, as shown in Figure 3 , 4 When the floating wind turbine 13 is in the normal working condition of the marine environment, it will bear the wind and wave load at the same time, and the anchor line will be subjected to tension, pulling the reserved mooring chain 8b and driving the load reduction device to move. When the anchor line load is transmitted to the load reduction device, the wing plate 9 rotates first, driving the buoy to rotate simultaneously. Due to the presence of the wing plate 9, the upper anchor line 14a and the lower anchor line 14b of the floating wind turbine 13 are not collinear in action, and the load reduction device is subjected to torque and rotates. The rotation process of the load reduction device allows the tension transmitted by the upper anchor line 14a to be buffered for a certain period of time before being transmitted to the lower anchor line 14b, thereby effectively reducing the impact of the anchor line tension in extreme environments. When the anchor line tension is too large, the load reduction device rotates significantly or even reaches the overturning state. At this time, due to the presence of the buoy 1, the anchor line will be subjected to the action of the buoyancy of the buoy, which can also effectively reduce the vertical tension component of the anchor line. During the rotation of the load reduction device, the damping wing plate 6 on the upper part of the buoy 1 and the circular heave plate 9 below the center weight 2 fully interact with the surrounding seawater, changing the flow field of the surrounding seawater and damping the tension impulse transmitted to the load reduction device, thereby further reducing the tension load borne by the lower anchor line 14b.

Claims

1. A method for installing a load-reducing device for a floating wind turbine mooring line, characterized in that, The device includes a pontoon (1), a central counterweight (2), a suspended counterweight (3), and two wing plates (9). The lower end of the pontoon (1) is coaxially fixedly connected to the central counterweight (2) through a connector, which is a detachable structure and constitutes the main body. The top of the pontoon (1) is reserved with a lifting lug for the overall hoisting of the device. Several damping wing plates (6) are uniformly fixed on the outer circumferential surface of the upper section of the pontoon (1). The suspended counterweight (3) is coaxially connected to the central counterweight (2) via a connecting mooring chain (8a); The wing plate (9) is an open "door" shaped steel plate. The two ends of the opening, i.e., the bottom ends of the "door", are connected to the main body by a hinge (11). The hinges (11) are symmetrical about the central axis of the main body, and the line connecting the two hinges (11) passes through the central axis. The two wing plates (9) are installed at different heights and in opposite directions on the main body. A first shackle (10a) is installed at the top center of the wing plate (9) for connecting with a reserved mooring chain (8b). The reserved mooring chain (8b) The other end is provided with a second shackle (10b) for connecting the entire device to the mooring line of the original floating wind turbine (13); the two wing plates (9) are set on both sides of the main body, wherein the hinge (11) of the left wing plate (9) is connected to the float (1); the hinge (11) of the right wing plate (9) is connected to the central counterweight (2), the wing plate (9) can rotate up and down with the hinge, and the top of the wing plate (9) is also reserved with an opening (12) for hoisting the wing plate (9); The steps of the method are as follows: Step 1: Connect the float (1) and the center counterweight (2) to form the main body, then connect the center counterweight (2) and the circular heave plate (7), install the hinge (11), and connect the wing plate (9) to the main body; connect the suspended counterweight (3) to the center counterweight (2) or the circular heave plate (7) through the connecting mooring chain (8a), install the top shackle of the wing plate (9), connect the reserved mooring chain (8b) to the wing plate (9), and complete the assembly of the load reduction device itself; Step 2: The crane lifts the load reduction device using the traction rope and the lifting lugs on the top of the device. When lifting, adjust the angle and orientation of the damping wing plate (6) to ensure that the device is lowered vertically until the device is lowered below the sea level. Divide the mooring line of the floating wind turbine (13) into two sections: the upper mooring line (14a) and the lower mooring line (14b). The two sections are connected to the two reserved mooring chains (8b) of the load reduction device through shackles. The entire mooring chain is pre-tensioned by the winch to complete the overall installation of the load reduction device and the floating wind turbine (13). Step 3: When the floating wind turbine (13) is in a normal marine environment, it will be subjected to the loads of wind, waves and currents. Its mooring line will be tensioned, pulling the reserved mooring chain (8b) and driving the load reduction device to move. When the load of the mooring line is transferred to the load reduction device, the wing plate (9) will rotate first, causing the float to rotate at the same time. Due to the presence of the wing plate (9), the upper mooring line (14a) and the lower mooring line (14b) of the floating wind turbine (13) will not be collinear. The load reduction device will be subjected to torque and rotate accordingly. The rotation process of the load reduction device will buffer the tension transmitted by the upper mooring line (14a) for a certain period of time before it is transmitted to the lower mooring line (14b). Therefore, it will effectively reduce the impact tension of the mooring line under extreme conditions. When the tension of the mooring line is too large, the load reduction device will rotate significantly or even reach the overturning state. At this time, due to the presence of the float (1), the mooring line will be subjected to the buoyancy of the float, thereby effectively reducing the vertical tension component of the mooring line.

2. The installation method of the unloading device for a floating wind turbine mooring line according to claim 1, characterized in that, The shape and mass of the central counterweight (2) and the suspended counterweight (3) can be determined according to the actual situation on site, and are used to adjust the center of gravity of the entire load reduction device.

3. The installation method of the unloading device for a floating wind turbine mooring line according to claim 1, characterized in that, The damping wing plate (6) is a square damping wing plate, and three of them are evenly fixed to the upper circumference of the buoy to follow the movement of the buoy (1) in the seawater and provide motion damping.

4. The installation method of the unloading device for a floating wind turbine mooring line according to claim 1, characterized in that, The pontoon (1) is a steel cylinder filled with foam material. The central counterweight (2) and the suspended counterweight (3) are both made of high-density concrete. The shape and diameter of the central counterweight (2) are consistent with those of the pontoon (1). The suspended counterweight (3) is a frustum shape. The suspended counterweight (3) has a pre-reserved lifting lug on the top and is connected to the central counterweight (2) by a mooring chain (8a).

5. The installation method of the unloading device for a floating wind turbine mooring line according to claim 1, characterized in that, The bottom of the central counterweight (2) is coaxially fixed with a circular heave plate (7), which is a thin circular steel plate. The circular heave plate (7) can play a wave-cutting role. At this time, the suspended counterweight (3) is connected to the center of the circular heave plate (7) through the connecting mooring chain (8a).

6. The installation method of the unloading device for a floating wind turbine mooring line according to claim 1, characterized in that, During the rotation of the load reduction device, the square damping wing plate (6) on the buoy (1) and the circular heave plate (7) below the central counterweight (2) interact fully with the surrounding seawater, changing the change in the surrounding seawater flow field, and playing a damping and dissipating role on the tension impulse transmitted to the load reduction device, thereby further reducing the tension load borne by the lower mooring line (14b).

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