Gravity-type variable-length seabed single point mooring connection apparatus for floating wind turbine

Abstract

A gravity-type variable-length seabed single point mooring connection apparatus for a floating wind turbine. The apparatus comprises: a floating body, carrying at least two pulley fairleads; a single point anchor, disposed on the seabed and to which a rotatable apparatus is connected; and at least one weight, located in the water below the floating body. The weight and the single point anchor are connected by means of a mooring cable passing through the pulley fairleads. The prevent invention has small seabed coverage area, is environmentally friendly, has high efficiency for a mooring system, and implements a wind vane function, and is safe, reliable, practical, and feasible. The present invention can be used in offshore mooring positioning of floating wind power platforms having a water depth of 50 meters to 300 meters or even more than 1500 meters.

Description

Gravity-based variable-length subsea single-point mooring connection device for floating wind turbines Technical Field

[0001] The present invention relates to a technology in the field of marine engineering structures, specifically a gravity-type variable-length submarine single-point mooring connection device that can be used for floating wind power platforms in water depths of 50 meters to 300 meters or even more than 1,500 meters. Background Art

[0002] Existing mooring and positioning technologies for offshore floating structures include catenary, tensioned (or semi-tensioned) leg, and tension-leg mooring. Catenary mooring leaves a large footprint (coverage area) on the seabed, significantly impacting the ocean water and seabed environment. Steel catenaries are too heavy and expensive for deepwater areas. For water depths less than 100 meters, the mooring cable / chain cannot form a sufficiently long catenary shape between the mooring point on the buoy and the anchor point on the seabed to provide the required mooring restoring force to limit the horizontal displacement of the offshore floating structure under external forces such as wind, waves, and currents. Consequently, its mooring and positioning capabilities are poor in shallow waters, and the required length of the mooring chain on the seabed is typically several times the water depth. This makes offshore installation difficult, time-consuming, and costly. The dynamic tension of a catenary mooring cable increases exponentially with the increase in the horizontal displacement of the offshore floating structure, posing significant challenges to mooring system design, including cable strength and fatigue issues.

[0003] Existing offshore floating wind turbine mooring systems primarily utilize a mooring system consisting of multiple anchors distributed on the seabed and connected mooring cables / chains. These anchors are distributed on the seabed, and the mooring points on the buoy (floating wind turbine) are also distributed outside the floating wind turbine foundation, protecting it from wind and waves from all directions. This approach suffers from low mooring efficiency. The anchors, in particular, can only withstand external wind and wave forces from one direction: from the seabed anchor point to the buoy mooring point. The anchors on these mooring cables are ineffective against forces from other directions.

[0004] Existing single-point mooring technology is primarily used for offshore floating production, storage, and offloading vessels (FPSOs). Specifically, multiple mooring lines are connected to a mooring point on a floating structure. This involves connecting multiple anchors distributed on the seabed via mooring lines to a rotatable, weathervaning single-point mooring device on the floating structure. This allows the FPSO to rotate around the single-point mooring device as external forces (wind, waves, and currents) change direction, with the bow always facing the direction of the external forces, effectively reducing wind and wave forces. However, the disadvantage is that the single-point mooring device installed on the ship (floating structure) is extremely complex and costly, and the distributed arrangement of multiple anchors on the seabed results in low mooring system efficiency.

[0005] Existing floating platform positioning technology using buoys cannot withstand harsh environments. For example, during typhoons, they experience violent movement with waves, causing fatigue fractures in their frame structures. The buoys experience significant displacement under the influence of waves, so even with structural reinforcement (which significantly increases costs), they cannot effectively locate the target floating platform. Existing technology based on underwater anchoring cannot effectively locate the target floating object, limiting its position in only one dimension. The mooring system is inefficient and lacks a weather vane function.

[0006] Summary of the Invention

[0007] The present invention addresses the design difficulties of existing catenary mooring connection devices and the problems of large seabed coverage area and low mooring system efficiency caused by the distributed arrangement of multiple seabed anchors adopted by existing single-point mooring devices. The present invention proposes a gravity-type variable-length seabed single-point mooring connection device for floating wind turbines. The device has a small seabed coverage area, is environmentally friendly, has a weather vane function, and has a high mooring system efficiency, which is safer, more reliable, and more practical.

[0008] The present invention is achieved through the following technical solutions:

[0009] The present invention relates to a gravity-type variable-length seabed single-point mooring connection device for a floating wind turbine, comprising: a floating body with at least two pulley fairleads, a single-point anchor arranged on the seabed, and at least one counterweight located in the water below the floating body, wherein: the counterweight and the single-point anchor are connected by a mooring cable passing through the pulley fairlead.

[0010] The floating body is provided with a tower and a wind power generation device.

[0011] The pulley fairlead is preferably symmetrically arranged outside the floating body, and more preferably centrally symmetrically arranged.

[0012] When one counterweight is used, the counterweight is connected to a single-point anchor arranged on the seabed through at least two mooring cables, each passing through a corresponding pulley fairlead; the counterweight is located directly below the floating body during operation.

[0013] When the floating body is in the initial equilibrium position, the single-point anchor is located at the intersection of the vertical centerline of the floating body and the seabed. The mooring points of multiple mooring cables / chains on the floating body are arranged geometrically symmetrically, and the counterweight is located vertically above the single-point anchor on the seabed and below the floating body.

[0014] When a floating body deflects horizontally from its initial equilibrium position under the action of an external force, the effective length of its mooring cable changes. Specifically, the length of the mooring cable between the floating body's mooring point and the single-point anchor on the seabed varies with the horizontal deflection of the floating body. Simultaneously, the counterweight moves up and down and left and right, its position changing with the corresponding effective length of the mooring cable. The sum of the vertical components of the tension in all mooring cables equals the weight of the counterweight. The tension in each mooring cable is non-constant, and its angle with the water surface varies. This creates a restoring force in the mooring system, whose absolute value is equal to the sum of the horizontal components of the tension in all mooring cables. This restoring force increases with the deflection of the floating body. When the deflection reaches a certain value, it becomes equal to the absolute value of the external force, but opposite in direction. When the external force disappears, the floating body returns to its initial position.

[0015] When more than two counterweights are used, each counterweight is connected to a single point anchor set on the seabed through a mooring cable passing through a corresponding pulley fairlead; each counterweight is located directly below the corresponding pulley fairlead when working.

[0016] When the floating body is in the initial equilibrium position, the single-point anchor is located at the geometric center of the mooring connection device on the seabed, that is, the intersection of the vertical centerline of the floating body and the seabed. The mooring points of multiple mooring cables / chains on the floating body are arranged in geometric symmetry, and the counterweight corresponding to each mooring cable is vertically located below the corresponding pulley fairlead and above the seabed.

[0017] When a floating body deflects horizontally from its initial equilibrium position due to external forces (wind, waves, currents), the effective length of the mooring cable between the mooring point on the floating body and the single-point anchor on the seabed changes with the displacement of the floating body. The tension in the mooring cable remains equal to the weight of the corresponding counterweight. At this time, the tension of each mooring cable remains constant, but the geometric angle with the water surface changes. This creates a restoring force in the mooring system, whose absolute value is equal to the sum of the horizontal components of all the mooring cable tensions. This restoring force increases with the displacement of the floating body. When the displacement reaches a certain value, it becomes equal to the absolute value of the external force, but opposite in direction. When the external force disappears, the floating body returns to its initial position.

[0018] The single-point anchor is equipped with a rotatable mooring connection on its upper portion. This rotatable mooring connection is connected to the mooring line, ensuring that the buoy and the wind turbine atop it always face the direction of the incoming wind, while also maintaining the fixed position of the single-point anchor. The single-point anchor is preferably a concrete gravity anchor, with a skirt plate at its bottom that sinks below the seabed mud surface and a cross-shaped watertight vertical bulkhead internally. The rotatable mooring connection is located at the center of the cross-shaped watertight vertical bulkhead and is internally equipped with a bearing rotation device.

[0019] The present invention relates to an integrated installation method based on the above-mentioned gravity-type variable-length submarine single-point mooring connection device. After a single-point anchor with a built-in vertical watertight bulkhead empty compartment and a counterweight are prepared by concrete, a mooring cable is used to connect the single-point anchor and the counterweight at a shore wharf, and a conventional marine transport lashing / fastening device is used to temporarily connect the single-point anchor and the floating body carrying the tower and wind turbine. A tugboat is used to tow the entire system in an integrated manner. When arriving at the offshore installation site, the marine transport lashing / fastening device of the single-point anchor is first released and seawater is injected into its empty compartment. Under gravity operation, the single-point anchor is automatically lowered to the seabed. Then, the counterweights are released one by one from the marine transport lashing / fastening device and lowered to a preset depth in the water. The mooring cables are tightened one by one, thereby completing the offshore installation of the wind turbine, the floating body and the mooring system in one go.

[0020] The marine transport lashing / fastening device may be, but is not limited to, temporary connection components such as ropes.

[0021] Technical Effects

[0022] Compared with the prior art, the technical effects of the present invention include:

[0023] i) This invention breaks away from the conventional constant-length mooring paradigm, where the physical length of the mooring line between the mooring point on the floating body (e.g., the fairlead) and the anchor point on the seabed is a constant value. Instead, it proposes a new variable-length mooring paradigm, where the physical length of the mooring line between the mooring point on the floating body (e.g., the fairlead) and the anchor point on the seabed is variable. This significantly reduces the maximum tension (static tension + dynamic tension) of the mooring line, greatly improving the safety, reliability, and fatigue life of the entire mooring system.

[0024] ii) The present invention reduces the footprint of the mooring system on the seabed to a minimum (only the size of an anchor), solving the problem that large-scale application of offshore floating wind power has a significant impact on the marine ecological environment and the shared utilization of marine resources.

[0025] iii) The present invention has a wind vane function, which enables the wind turbine to always face the direction of the incoming wind, thereby significantly improving the power generation efficiency of the wind turbine.

[0026] iv) The present invention can complete the offshore installation of the wind turbine, floating body and mooring system in one go through an integrated installation method, which greatly saves the offshore installation time and cost of the mooring system and significantly improves the offshore installation efficiency of the entire floating wind power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a two-dimensional schematic diagram of a gravity-type variable-length non-constant-tension submarine single-point mooring connection device;

[0028] FIG2 is a two-dimensional schematic diagram of the horizontal displacement of the floating body of a gravity-type variable-length non-constant-tension submarine single-point mooring connection device;

[0029] FIG3 is a three-dimensional rendering of a gravity-type variable-length non-constant-tension submarine single-point mooring connection device;

[0030] FIG4 is a two-dimensional schematic diagram of the fairlead of a gravity-type variable-length non-constant-tension submarine single-point mooring connection device, including pulleys and connection structures, and local details of the counterweight;

[0031] FIG5 is a three-dimensional schematic diagram of a partial detail of a counterweighted mooring cable connection lug of a gravity-type variable-length non-constant-tension submarine single-point mooring connection device;

[0032] FIG6 is a two-dimensional schematic diagram of a gravity-type variable-length constant-tension submarine single-point mooring connection device;

[0033] FIG7 is a two-dimensional schematic diagram of the horizontal deflection of the floating body of the gravity-type variable-length constant-tension submarine single-point mooring connection device;

[0034] FIG8 is a side view of a partial detail of the pulley fairlead and counterweight of a gravity-type variable-length constant-tension submarine single-point mooring connection device;

[0035] FIG9 is a three-dimensional schematic diagram of the connection between the gravity-type variable-length constant-tension submarine single-point mooring connection device and the floating wind turbine platform at the dock;

[0036] FIG10 is a side view of the gravity-type variable-length constant-tension submarine single-point mooring connection device and the floating wind turbine platform being towed at sea;

[0037] FIG11 is a three-dimensional schematic diagram of the installation of a seabed single-point gravity anchor for a gravity-type variable-length constant-tension seabed single-point mooring connection device;

[0038] FIG12 is a three-dimensional schematic diagram of the counterweight lowering and installation of a gravity-type variable-length constant-tension submarine single-point mooring connection device;

[0039] In the figure: 2 floating body, 2A floating body upper hull, 2B floating body lower hull, 4 wind tower, 6 wind turbine nacelle, 8 wind turbine blades, 30 fairlead, 30A vertical axial rotation mechanism, 30B supporting structure, 30R pulley, 31 floating mooring point, 31A connecting structure, 31B fairlead rotation structure, 32 mooring cable, 32L left mooring cable, 32R right mooring cable, 34 counterweight, 34A mooring connector, 34B connecting chain, 36 rotatable single point mooring connection device, 38 seabed single point anchor, 42 mooring connector lower structure, 44 mooring cable Mooring connector upper structure, 46 mooring connector ear plate, 48 mooring connector connection inner plate, 50 fairlead, 50A pulley, 50B vertical axial rotation mechanism, 50C supporting structure, 51 floating mooring point, 51A connection structure, 52A one end of the mooring cable, 52B the other end of the mooring cable, 54 counterweight, 56 rotatable single-point mooring connection device, 58 seabed single-point anchor, 101 water surface, 201 seabed / seabed, 301 wind load, 302 wave load, 401 mooring system restoring force, 501 tugboat, 601 gravity. DETAILED DESCRIPTION

[0040] Example 1

[0041] As shown in Figures 1 to 3, this embodiment relates to a gravity-type variable-length non-constant tension submarine single-point mooring connection device, including: a mooring connection device 1, a floating body 2, multiple fairleads 30, multiple mooring cables 32, a large counterweight 34 and an attached mooring connector 34A, a submarine single-point anchor 38 located on the seabed 201, and an attached rotatable single-point mooring connection device 36, wherein: each fairlead 30 is connected to a floating mooring point 31 of the lower hull 2B of the floating body, and each mooring cable 32 passes through the corresponding fairlead 30, with one end connected to the counterweight 34 and the other end connected to the rotatable single-point mooring connection device 36 located above the submarine single-point anchor 38.

[0042] The upper hull 2A of the floating body is located above the water surface 101, and the lower hull 2B of the floating body is located below the water surface 101. A wind tower 4 is provided on the upper hull 2A of the floating body for supporting a wind turbine nacelle 6 located at the top of the wind tower 4 and wind blades 8 connected to the wind turbine nacelle 6.

[0043] When the buoy 2 is in its initial equilibrium position, the seabed single-point anchor 38 is located at the geometric center of the mooring connection 1 on the seabed, i.e., at the intersection of the vertical centerline of the buoy 2 and the seabed 201. Multiple fairleads 30 and corresponding mooring cables 32 are arranged geometrically symmetrically at corresponding buoy mooring points 31 on the buoy 2. A counterweight 34 is positioned vertically above the seabed single-point anchor 38 and a certain distance below the lower hull 2B of the buoy. The sum of the vertical components of the tension in all mooring cables 32 is equal to the weight of the counterweight 34. Due to the symmetrical arrangement, the initial tension in each mooring cable 32 is equal.

[0044] When the floating body 2 deviates horizontally to the right under the action of external wind loads 301 and wave loads 302, the effective length of the mooring lines 32L and 32R, that is, the length of the mooring lines between the floating mooring point 31 and the single-point anchor 38 on the seabed, changes with the horizontal deviation of the floating body 2, with 32L becoming shorter and 32R becoming longer. At the same time, the counterweight 34 and its attached mooring connector 34A connected to the mooring lines 32L and 32R move up and down and left and right to maintain the total physical length of each mooring line 32L and 32R from the counterweight 34 to the single-point anchor 38 on the seabed unchanged. At this point, the horizontal angles of mooring cables 32L and 32R relative to buoyant mooring point 31 change, and the tensions become unequal. The sum of the vertical components of the tension in mooring cables 32L and 32R equals the weight of counterweight 34. The horizontal component of the tension in mooring cable 32L decreases, while the horizontal component of the tension in mooring cable 32R increases. The resulting horizontal resultant of the tension in all mooring cables 32L and 32R in mooring connection 1 is greater than zero and directed to the left. This generates a restoring force 401 for the mooring system, which is opposite in direction to the external forces of wind load 301 and wave load 302 and equal in absolute value. This achieves dynamic equilibrium with the horizontal displacement of floating hull 2. This restoring force 401 increases with increasing horizontal displacement of floating hull 2. Its magnitude can be calculated based on the internal tension in mooring cables 32L and 32R, the water depth, and the magnitude of the horizontal displacement of floating hull 2. The initial internal tension in mooring cables 32L and 32R is determined by the weight of counterweight 34 and its position in the water.

[0045] A rotatable mooring connection 36 with a weather vane function is installed above the seabed single-point anchor 38, allowing the floating body 2 to rotate in response to the external forces 301 and 302. The wind turbine systems 6 and 8 located above the floating body 2 always face the direction of the external forces 301 and 302. This weather vane function significantly improves the wind turbine's power generation efficiency. When the external force disappears, the restoring force 401 of the mooring system returns the floating body 2 to its initial position.

[0046] The single-point anchor 38 is preferably a concrete gravity anchor with a cross-shaped vertical watertight bulkhead installed inside. The rotatable mooring connection 36 is located at the center of the cross-shaped vertical watertight bulkhead and includes a bearing rotation mechanism. The concrete gravity anchor is equipped with a skirt at the bottom, which sinks below the seabed mud surface under the action of gravity to provide horizontal resistance.

[0047] As shown in Figure 3, when three fairleads 30 and corresponding three floating mooring points 31 are provided on the floating body 2, three mooring cables 32 are used and each mooring cable 32 passes through the corresponding fairlead 30, one end of which is connected to the counterweight 34, and the other end is connected to the rotatable single-point mooring connection device 36 located above the single-point anchor 38 on the seabed.

[0048] When the buoy 2 is in the initial equilibrium position, the seabed single-point anchor 38 is located at the geometric center of the mooring connection device 1 on the seabed, that is, the intersection of the vertical center line of the buoy 2 and the seabed 201. The three fairleads 30 are arranged geometrically symmetrically on the buoy 2, and the counterweight 34 is vertically located above the seabed single-point anchor 38 and a certain distance below the buoy 2. In this symmetrical arrangement state, the initial tension of each mooring cable 32 is equal, and the sum of the vertical components of the tension of all mooring cables 32 is equal to the weight of the counterweight 34.

[0049] The mooring cable 32 is a steel cable, a steel chain, a polyester cable or a nylon cable or a combination thereof.

[0050] The counterweight 34 is made of concrete, steel, or other heavy materials, or a combination thereof. It has multiple internal compartments, allowing it to temporarily float on the water. A mooring connector 34A, comprising three lugs, is provided for connecting a mooring cable. The seabed single-point anchor 38 can be a suction anchor, a driven anchor, or a gravity anchor.

[0051] As shown in Figure 4, the fairlead 30 is located on the right side of the lower hull 2B of the floating body, and includes: a pulley 30R with a groove, a set of vertical axial rotation mechanisms 30A, a support structure 30B and a mooring cable 32R, wherein: the vertical axial rotation mechanism 30A is connected to the floating mooring point 31 through a connecting structure 31A, one end of the mooring cable 32R is connected to a single-point anchor on the seabed (not shown in the figure), changes direction upward through the groove of the pulley 30R, and the other end is connected to the mooring connector 34A, and the size of the groove of the pulley 30R matches the size of the mooring cable 34A.

[0052] The upper end of the mooring connector 34A is also connected to the mooring line 32L on the left side, and the lower end is connected to the upper end of the counterweight 34 through the connecting chain 34B.

[0053] As shown in FIG5 , the mooring connector 34A includes a lower structure 42 , an upper structure 44 , three ear plates 46 for connecting corresponding mooring lines 32 , and a plurality of connecting inner plates 48 , wherein the lower structure 42 is connected to the counterweight 34 via a connecting chain 34B.

[0054] In practical applications, the weight of counterweight 34 typically depends on the magnitude of the maximum external wind and wave forces. For large (e.g., 15 MW) floating offshore wind turbines, the weight range is typically 500-1000 tons or more. Because counterweight 34 is quite heavy (hundreds of tons) and is suspended below buoy 2, it can increase the stability of buoy 2.

[0055] Example 2

[0056] As shown in Figures 6-8, this embodiment relates to a gravity-based, variable-length, constant-tension submarine single-point mooring connection. Specifically, as shown in Figure 6, when two counterweights and two mooring cables are used, each mooring cable 52 passes through a corresponding fairlead 50, with one end vertically downwardly connected to the corresponding counterweight 54 and the other end connected to a rotatable single-point mooring connection 56 located above a submarine single-point anchor 58. When the buoy 2 is in its initial equilibrium position, the submarine single-point anchor 58 is located at the geometric center of the mooring connection 1A on the seabed, i.e., at the intersection of the vertical centerline of the buoy 2 and the seabed 201. Each fairlead 50 and its corresponding mooring cable 52 are geometrically symmetrically arranged at the corresponding buoy mooring point 51 on the buoy 2. The counterweight 54 is positioned vertically below the corresponding fairlead 50 by a certain distance, and the tension of the mooring cable 52 is equal to the weight of the corresponding counterweight 54.

[0057] As shown in FIG7 , when the floating body 2 is horizontally deflected to the right by the external wind load 301 and wave load 302, the effective lengths of the mooring lines 52L and 52R, i.e., the lengths of the mooring lines between the floating mooring point 51 and the seabed single-point anchor 58, change as the horizontal deflection of the floating body 2 changes, with the mooring line 52L becoming shorter and the mooring line 52R becoming longer. Simultaneously, the counterweight 54L moves downward and the counterweight 54R moves upward to maintain the total physical length of each mooring line (52L and 52R) from the corresponding counterweight (54L and 54R) to the seabed single-point anchor 38 unchanged. At this point, the horizontal angles of mooring cables 52L and 52R relative to their corresponding buoyant mooring points 51 change, causing the horizontal component of the tension in mooring cable 52L to decrease and the horizontal component of the tension in mooring cable 52R to increase. The resulting horizontal resultant of the tension in all mooring cables 52L and 52R of mooring connection 1A is greater than zero and directed leftward. This generates a restoring force 401 for the mooring system, which is opposite in direction to the external forces acting on it, wind load 301 and wave load 302, and has the same absolute value. This achieves dynamic equilibrium in the horizontal displacement of floating hull 2. This restoring force 401 increases with increasing horizontal displacement of floating hull 2. Its magnitude can be calculated based on the internal tension in mooring cables 52L and 52R, the water depth, and the horizontal displacement of floating hull 2. The internal tension in mooring cables 52L and 52R is constant, equal to the weight of their corresponding counterweights 54L and 54R. When the external forces disappear, this restoring force 401 returns floating hull 2 ​​to its initial position.

[0058] A rotatable mooring connection 56 with a weather vane function is located above the seabed single-point anchor 58. This device comprises a vertical axial rotation mechanism, a connecting structure, and a mooring connector with at least three lugs for connecting mooring cables. This allows the buoy 2 to rotate in response to external forces 301 and 302, while the wind turbine systems 6 and 8 above it always face the direction of external forces 301 and 302. This weather vane function significantly improves the wind turbine's power generation efficiency.

[0059] The single-point anchor 58 is preferably a concrete gravity anchor with a cross-shaped vertical watertight bulkhead installed inside. The rotatable mooring connection 56 is located at the center of the cross-shaped vertical watertight bulkhead and includes a bearing rotation mechanism. The concrete gravity anchor is equipped with a skirt at the bottom, which sinks below the seabed mud surface under the action of gravity to provide horizontal resistance.

[0060] As shown in FIG8 , the fairlead 50 is located on the right side of the lower hull 2B of the floating body and includes a pulley 50A with a groove, a set of vertical axial rotation mechanisms 50B and a support structure 50C. The fairlead 50 is connected to the floating mooring point 51 through a connecting structure 51A.

[0061] The mooring cable comprises a vertical section 52A and an inclined section 52B. One end of the vertical section 52A is connected vertically downward to a corresponding counterweight 54, then changes direction upward through a groove in pulley 50A. One end of the inclined section 52B is connected to the vertical section 52A in a groove in pulley 50A, and the other end is connected to a single-point anchor on the seabed (not shown). The groove in pulley 50A is sized to match the diameter of the mooring cable.

[0062] When the floating body 2 generates vertical axial rotation, the vertical axial rotation mechanism 50B drives the pulley 50A and the mooring cables 52A and 52B to rotate around the vertical axis.

[0063] When the gravity-based variable-length constant-tension submarine single-point mooring connection is actually applied to a floating wind turbine platform, it typically uses three equal counterweights, three fairleads, and three mooring cables. The weight of the counterweights depends on the magnitude of the maximum external wind and wave forces. For large (e.g., 15 MW) floating offshore wind turbines, each counterweight typically weighs 300-700 tons or more. Because the counterweights are quite heavy (hundreds of tons) and are suspended below the floating wind turbine platform, their stability is enhanced.

[0064] As shown in FIG9 , the seabed single-point anchor 58 is a reinforced concrete structure with multiple vertical watertight bulkhead compartments built into it, allowing it to temporarily float on the water. It is connected to a rotatable mooring connection device 56 at its upper portion and is integrated with the buoy 2, wind tower 4, wind turbine nacelle 6, wind turbine blades 8, fairlead 50, mooring cable 52, and counterweight 54 at the dockside to form a floating wind turbine integrated system 1B. The mooring cable 52, counterweight 54, seabed single-point anchor 58, and buoy 2 are temporarily connected via an offshore fastening / lashing device (not shown). Specifically, the buoy 2 has three columns, three fairleads 50, three mooring cables 52, and three counterweights 54 of equal weight.

[0065] This embodiment relates to the above-mentioned floating wind turbine overall system 1B, which is installed offshore through the following method and process.

[0066] In the first step, as shown in Figure 10, the tugboat 501 tows the floating body 2, wind tower 4, wind turbine nacelle 6 and wind turbine blades 8, fairlead 50, mooring line 52, counterweight 54, seabed single point anchor 58 and its attached rotatable mooring connection device 56 to the offshore wind farm location.

[0067] In the second step, as shown in Figure 11, after reaching the offshore wind farm location, the seabed single-point anchor 58 and its corresponding mooring cable 52 are released from the offshore fastening / binding device, and seawater is injected into its empty compartment. Under the action of gravity 601, the seabed single-point anchor 58 and its attached rotatable mooring connection device 56 sink to the seabed 201.

[0068] In the third step, as shown in FIG12 , the counterweights 54 and their corresponding offshore fastening / binding devices of the mooring lines 52 are released one by one. Under the action of gravity 601 , the counterweights 54 sink to a predetermined depth in the water, tightening the mooring lines 52 to complete the installation of the gravity-type variable-length constant-tension submarine single-point mooring connection device of the present invention.

[0069] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A gravity-type variable-length non-constant tension submarine single-point mooring device, characterized in that: include: A floating body connected to a wind tower above the water surface supports a set of wind power generation equipment. A large shared underwater weight located vertically a certain distance below the center of the float, A single point anchor on the seabed, Multiple mooring lines, Multiple fairleads are connected to the corresponding floating mooring points. Among them: each mooring cable passes through the corresponding fairlead, one end of which is connected to the shared underwater weight at the bottom, and the other end is connected to the single-point anchor on the seabed. The sum of the vertical components of the tension of all mooring cables is equal to the weight of the shared underwater weight; When the floating body produces horizontal displacement, the shared weight in the water moves up and down and left and right. The effective length of each mooring cable, that is, the length between the floating mooring point and the single-point anchor on the seabed, changes with the displacement of the floating body, generating a restoring force of the mooring system. The upper part of the seabed single-point anchor is provided with a rotatable mooring device with a weather vane function, and the rotatable mooring device includes: a set of vertical axial rotation mechanisms, a connecting structure and a mooring connector with at least three ear plates, which are used for connecting mooring cables, so that the floating body rotates in the direction of the external environmental force.

2. The gravity-type variable-length non-constant-tension seabed single-point mooring device according to claim 1 is characterized in that: The floating mooring point, fairlead and mooring cable constitute a mooring unit, which has at least three sets; The floating system mooring points are arranged symmetrically; The seabed single point anchor is located at the geometric center of the mooring device on the seabed, that is, the intersection of the vertical center line of the floating body and the seabed; The shared underwater weight is vertically located above the single-point anchor on the seabed.

3. The gravity-type variable-length non-constant-tension seabed single-point mooring device according to claim 1 is characterized in that: The shared underwater weight block is made of concrete, steel or a combination thereof, and is provided with a plurality of empty compartments for temporary floating on the water surface; A mooring connector having at least three lugs is provided on the upper portion of the shared underwater weight for connecting a mooring cable; The seabed single point anchor is a suction anchor pile, a driven anchor pile or a gravity anchor; The mooring cable / chain is a steel cable, a steel chain, a polyester cable, a nylon cable or a combination thereof.

4. The gravity-type variable-length non-constant-tension seabed single-point mooring device according to claim 1 is characterized in that: The fairlead comprises: a pulley with a groove, a set of vertical axial rotation mechanism and a connecting structure, wherein: the pulley is connected to the corresponding floating mooring point through the connecting structure, one end of the mooring cable is connected to a shared underwater weight block, changes direction through the pulley groove, and the other end is connected to a single-point anchor on the seabed, and the vertical axial rotation mechanism rotates the pulley and the mooring cable around its vertical axis.

5. A gravity-type variable-length constant-tension submarine single-point mooring device, characterized in that: include: A floating body connected to a wind tower above the water surface supports a set of wind power generation equipment. A single point anchor on the seabed, Multiple mooring lines, Multiple fairleads are connected to the corresponding floating mooring points on the floating body. Multiple water weights, Wherein: each mooring cable passes through a corresponding fairlead, one end of which is vertically connected downward to a corresponding underwater weight, and the other end is connected to a single-point anchor on the seabed. The underwater weight is vertically located under the corresponding fairlead, and the tension of the mooring cable is equal to the weight of the underwater weight; When the floating body deflects horizontally, the weight in the water moves up and down, and the effective length of each mooring cable, that is, the length between the floating mooring point and the single-point anchor on the seabed, changes with the displacement of the floating body, generating a restoring force for the mooring system. The upper part of the seabed single-point anchor is provided with a rotatable mooring device with a weather vane function, which comprises: a set of vertical axial rotation mechanisms, a connecting structure and a mooring connector with at least three lugs, which are used for connecting mooring cables so that the floating body rotates in the direction of the external environmental force.

6. The gravity-type variable-length constant-tension seabed single-point mooring device according to claim 5 is characterized in that: The floating mooring point, fairlead, mooring cable and underwater weight constitute a mooring unit, which has at least three sets; The floating system mooring points are arranged symmetrically; The seabed single point anchor is located at the geometric center of the mooring device on the seabed, that is, the intersection of the vertical center line of the floating body and the seabed; The mooring cable is a steel cable, a steel chain, a polyester cable, a nylon cable or a combination thereof; The underwater weight block is made of reinforced concrete material, steel material or a combination thereof.

7. The gravity-type variable-length constant-tension seabed single-point mooring device according to claim 5 is characterized in that: The fairlead comprises: a pulley with a groove, a set of vertical axial rotation mechanisms and a support structure, wherein: the pulley is connected to the corresponding floating mooring point through the support structure, one end of the mooring cable is vertically connected to the corresponding underwater weight block downward, changes direction upward through the pulley groove, and the other end is connected to the seabed single point anchor, and its internal tension is equal to the weight of the corresponding underwater weight block; When the floating body generates a vertical axial rotation, the vertical axial rotation mechanism rotates around its vertical axis together with the pulley and the mooring cable.

8. An integrated installation method based on the gravity-type variable-length constant-tension submarine single-point mooring device according to any one of claims 5 to 7, characterized in that: The seabed single-point anchor is a reinforced concrete structure with a cross-shaped vertical watertight bulkhead inside, and is provided with a plurality of empty compartments inside for temporary floating on the water surface. The upper part thereof is connected to a rotatable mooring device with a weather vane function located at the center of the cross-shaped vertical watertight bulkhead, and is integrated with the floating body, the wind turbine system and the mooring device at the dock shore to form a floating wind turbine overall system, wherein the mooring cable, the underwater weight and the seabed single-point anchor are respectively temporarily connected to the floating body through an offshore fastening device; The fan system comprises: a wind tower, a fan nacelle and fan blades; The mooring device comprises: a fairlead, a mooring cable and an underwater weight; The bottom of the concrete gravity anchor is provided with a skirt plate, which can sink below the seabed mud surface under the action of gravity.

9. The integrated installation method according to claim 8, characterized in that: The floating wind turbine overall system floats on the water and is towed to the offshore wind farm by a tugboat.

10. The integrated installation method according to claim 8, characterized in that: The floating wind turbine overall system is in place at the offshore wind farm location. First, the seabed single-point anchor and the corresponding offshore fastening device of the mooring cable are released, and seawater is injected into its empty compartment. Under the action of gravity, the seabed single-point anchor and its attached rotatable mooring device sink to the seabed. Then, the underwater weights and the corresponding offshore fastening devices of the mooring cable are released one by one. Under the action of gravity, the underwater weights sink to a predetermined depth in the water, and the mooring cable is tightened to complete the installation of the mooring device.

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