Downwind floating wind turbine outer tower suspended single point mooring method and system

Abstract

The application discloses a downwind floating type wind turbine outer rotating tower suspension type single-point mooring method and system, which comprises the following steps: a mooring chain is laid by a work ship, and the end of the mooring chain is suspended by using a buoyancy-adjustable off-line buoy; a mooring connector provided with a dynamic submarine cable is lowered and connected with the mooring chain; after the floating platform is submerged and connected with the mooring connector, the off-line buoy is unloaded by being filled with water and is recovered; the mooring chain is tensioned by using an on-line tensioner; the platform is adjusted to a running draft to make the mooring connector suspended, the dynamic submarine cable is connected to a high-voltage switch cabinet and a high-voltage slip ring, and finally, rotation test is carried out. The mooring method and system can realize rapid installation, controlled connection and convenient maintenance, solve the problems of long construction period and high cost of offshore mooring and back connection of the floating type wind turbine, high requirement of the mooring bearing and inconvenience of maintenance and mooring monitoring, and belongs to the technical field of deep-sea floating type wind power generation equipment.

Description

Technical Field

[0001] This invention relates to the field of deep-sea floating wind power generation equipment technology, specifically to a method and system for suspending the outer turret of a downwind floating wind turbine at a single point. Background Technology

[0002] With near-shore wind power resources nearing saturation, deep-sea wind power has become the core direction for wind power development. Traditional fixed foundations are unsuitable for deep-sea areas, making floating wind power the optimal solution.

[0003] Floating wind turbines are classified into single-point mooring and multi-point mooring types according to their mooring methods. Conventional floating units mostly adopt multi-point mooring and upwind layout, which requires the configuration of a complex active yaw system, and involves a large number of mooring cables, resulting in high costs and complicated layout.

[0004] The single-point mooring structure, combined with the downwind rotor layout, allows the floating platform to passively rotate with the wind and waves, eliminating the need for an active yaw mechanism. This significantly simplifies the mooring system and control strategy, while also avoiding the risk of blade sweeping and reducing the overall load. It is suitable for severe sea conditions such as typhoons and strong waves, and is also well-suited to the low-cost, lightweight, and high-reliability development requirements of large-scale deep-sea wind turbines.

[0005] However, the existing single-point mooring solution has obvious drawbacks:

[0006] (1) Long installation period and high cost: The conventional single-point mooring system installation involves towing the unit into place and then reconnecting the mooring anchor chains one by one to the floating unit. This results in a long construction period, high risk, difficult construction, and the need for large construction vessels to cooperate.

[0007] (2) Difficult maintenance of mooring bearings: In conventional single-point mooring systems, the mooring bearings are located underwater. The water tightness requirements for the mooring bearings are extremely high, making maintenance difficult. If a fault occurs and replacement is needed, the unit must be towed back to port, which is extremely costly.

[0008] (3) Inconvenient monitoring and maintenance of mooring anchor chains: The mooring anchor chains are located underwater, making maintenance and condition monitoring difficult. It is often necessary to lower an ROV for maintenance and inspection. For the maintenance of some mooring monitoring equipment, diving is also required, which is both dangerous and costly.

[0009] 4) The installation and docking process relies on manual experience: During the single-point mooring reconnection process, the mooring connectors, offline buoys, platform ballast tanks, mooring chain tension, and the coaxiality of the outer turret bearings all affect each other. If only manual experience is relied upon to control the platform's submersion, buoy water intake and drainage, and mooring chain tension, problems such as large docking deviations, uneven mooring chain tension, or sudden changes in platform attitude are likely to occur. Summary of the Invention

[0010] To address the technical problems existing in the prior art, the purpose of this invention is to provide a method for single-point mooring of the outer turret of a downwind floating wind turbine, which enables rapid installation, controlled docking, convenient maintenance, and platform detachment.

[0011] Another objective of this invention is to provide a downwind floating wind turbine external turret suspended single-point mooring system.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: a leeward floating wind turbine external turret suspension single-point mooring method, comprising the following steps.

[0013] S1, Pre-laying of mooring anchor chains: Six mooring anchor chains are laid by positioning the work vessel. Each mooring anchor chain is connected to an offline buoy that can be inflated and deflated via a quick connector. The offline buoy keeps the ends of the six mooring anchor chains floating on the sea surface.

[0014] S2, Connect the dynamic submarine cable: Insert the dynamic submarine cable into the mooring connector, pass it out from the middle of the mooring connector, and reserve a redundant length.

[0015] S3, lowering the mooring connector: lower the mooring connector with the connected dynamic submarine cable to the sea surface, and connect the mooring anchor chain to the main lug of the mooring connector in sequence;

[0016] S4, Platform Submersion and Docking: The tugboat tows the floating platform to the installation position, uses the tugboat to adjust the floating platform to align with the mooring connector, applies ballast to the floating platform for submersion, and during the ballast submersion process, the tugboat continuously adjusts the position of the floating platform to keep it aligned with the mooring connector, and docks the floating platform with the mooring connector.

[0017] S5, Offline Float Unloading and Recovery: The six offline floats are filled with water to replace some or all of the gas inside the floats with water. After the six mooring chains gradually return to their catenary positions, the quick couplings are released to separate the mooring chains from the offline floats. Then, the water inside the offline floats is gradually emptied to allow them to float to the surface for recovery.

[0018] S6, Mooring chain tensioning: The mooring chain is tensioned using an online tensioner;

[0019] S7, Platform Load Adjustment: By adjusting the load on the floating platform to the normal operating draft of the unit, the mooring connector and the end of the mooring anchor chain are lifted out of the water to make them suspend, and then the dynamic submarine cable is connected to the high-voltage switch cabinet and high-voltage slip ring on the floating platform.

[0020] S8, Rotation Test: Use a tugboat to carry the floating platform around the mooring point to conduct a rotation test to check for interference, smooth rotation, and the availability of single-point mooring.

[0021] This method enables rapid reconnection at sea, significantly shortening the construction cycle and reducing installation costs and risks. It also enables the floating platform and mooring system to be quickly separated, facilitating platform movement and system reuse. Furthermore, by coordinating the control of the ballast tank, offline buoys, and mooring chain tensioning process, the controllability of the docking process between the outer turret mooring bearing and the mooring connector is effectively improved, significantly reducing the risk of sudden changes in mooring chain tension and eccentric loading of the guide structure. At the same time, by placing the mooring bearing above water, the sealing requirements are reduced and on-site maintenance and replacement are facilitated. Moreover, by exposing the end of the mooring chain above the water, convenient visual inspection and on-water maintenance are achieved.

[0022] As a preferred option, after the mooring connector is lowered, step S4.1 is performed first, floating standby: acquiring the mooring anchor chain tension, offline buoy pressure or liquid level, and mooring connector attitude data, and adjusting the water intake and air volume in each offline buoy to keep the mooring connector at the target exposed height and basic horizontal attitude.

[0023] As a preferred option, the water level inside the offline buoy is obtained through a pressure or level detection interface, and temporary pipelines are constructed via a work vessel for water inflow and outflow; The effective buoyancy of an offline pontoon is estimated using the following formula:

[0024]

[0025] in, For the first Effective buoyancy of an offline pontoon; The density of seawater; It is the acceleration due to gravity; For the first Total internal volume of each offline pontoon; For the first The volume of water entering the non-online pontoon; For the first The weight of the offline pontoon itself;

[0026] When the The change in water inlet volume for each offline pontoon is When the effective buoyancy changes, it is expressed as:

[0027]

[0028] Based on the correspondence between the water inflow volume and effective buoyancy of each offline buoy, and according to the mass of the mooring connector, the position of the buoy center, the arrangement of the main lugs, the angle of entry of the mooring anchor chain, the connection position of the offline buoy, and the field calibration data, a static balance or calibration model is established between the water inflow and outflow of the offline buoy and the exposed height, attitude deviation, and tension change of the mooring anchor chain. The static balance or calibration model is written as follows:

[0029]

[0030]

[0031] in, This represents the predicted change in the condition of the mooring connections for this period. This is the non-online pontoon adjustment response coefficient matrix; This refers to the change in the exposed height of the mooring connection. , These represent the changes in the lateral and longitudinal attitude angles of the mooring connectors, respectively. For the first The change in tension of the mooring chain; This is a vector composed of the changes in the water inlet volume of each offline pontoon;

[0032] Based on the height of the target exposure Allowable attitude deviation and target tension Based on this, the recommended water inflow and outflow of each offline buoy is calculated step by step. After execution, the buoy pressure or liquid level, mooring connection attitude and mooring anchor chain tension data are reread until the exposed height, attitude and tension are within the set range.

[0033]

[0034]

[0035] in, For the first The maximum flow rate of a non-online temporary inlet / outlet pipeline or pump valve for a float; This is the current exposed height of the mooring connector; Allowable deviation for exposed height; , These are the upper limits of the allowable attitude angles of the mooring connectors.

[0036] As a preferred embodiment, the floating platform is equipped with a mooring bearing for docking with the mooring connector. The mooring bearing has a side guide cylinder, and the mooring connector has a top guide cylinder. The top and side guide cylinders are guided by guide strips and positioned by locating pins. The platform's submersion and docking process specifically includes the following steps:

[0037] S4.2, Coarse Alignment: After the tugboat tows the floating platform to the vicinity of the installation position, based on the detection results of the floating platform's position, attitude and coaxial deviation, a coarse alignment prompt is output to the tugboat or on-site personnel to ensure that the mooring bearing is within the allowable range above the top guide cylinder of the mooring connector;

[0038] S4.3, Controlled Descent: Water is introduced into the ballast tank of the floating platform to make the floating platform descend at a preset speed. At the same time, the heel, trim, draft, coaxial deviation and tension parameters of each mooring chain of the floating platform are monitored. If any parameter exceeds the allowable range, the descent is suspended or the platform is surfaced to reset.

[0039] S4.4, Guide engagement: When the coaxial deviation meets the guide engagement condition, reduce the diving speed so that the side guide cylinder of the mooring bearing gradually engages with the top guide cylinder of the mooring connector, and maintain the stability of the platform attitude during the stage of guide bar contact or locating pin hole alignment.

[0040] S4.5, Flange Fastening: After the guide is engaged, maintain the ballast condition, and the construction personnel complete the installation of the positioning pins, bolts and sealing structure.

[0041] As a preferred embodiment, the center coordinates of the side guide tubes of the floating platform are as follows: , The center coordinates of the top guide tube of the mooring connector are marked as , The angle of the side guide cylinder axis is denoted as The angle of the axis of the top guide cylinder of the mooring connector is denoted as The tilt angle of a floating platform is denoted as... The tilt angle of the floating platform is denoted as ;No. The anchor chain tension of the root mooring is denoted as The reference tension is denoted as The diving speed of the floating platform is denoted as... ;

[0042] Coaxial deviation is calculated as follows:

[0043]

[0044]

[0045]

[0046]

[0047] in, , This refers to the deviation of the centers of the side guide cylinder and the top guide cylinder in the horizontal plane; This refers to the angular deviation between the axes of the side guide cylinder and the top guide cylinder; The sum of squares of the horizontal deviations is used to determine whether entering the guide engagement stage is permitted;

[0048] During the controlled descent phase, using coaxial deviation, platform attitude, ballast tank level, and anchor chain tension as inputs, the inflow and outflow control parameters for each ballast tank are calculated. The objective function is written as:

[0049]

[0050] in, The objective function for controlled descent is... to These are the weighting coefficients. To correspond to the reference tension of the mooring anchor chain at this stage, The platform's diving speed; when the coaxial deviation, platform attitude, or mooring anchor chain tension change rate exceeds the preset threshold, ballast water intake is suspended, the current draft is maintained, or the floating platform is controlled to rise to a safe height and then re-aligned.

[0051] Using the current cycle's water inflow and outflow increment of each ballast tank or ballast tank as the control variable, for m ballast tanks with adjustable water volumes, the current water volume of the k-th ballast tank is V. k The increase in water inflow and outflow during this cycle is ΔV k Then the control variable is represented as:

[0052] Based on the overall layout of the floating platform, the location of each ballast tank, the flow rate of pumps and valves, and on-site calibration data, a ballast response model is established. The ballast response model is obtained through hydrostatic calculations, tank tests, numerical simulations, or on-site pressure testing and calibration, and is stored in the form of a response coefficient matrix or a lookup table. The simplified expression of the ballast response model is:

[0053]

[0054]

[0055] in, Forecast response volume for this period; This is the ballast response coefficient matrix; This refers to the change in draft of the floating platform; For the first The change in tension of the mooring chain; This represents the change in the tilt angle of the floating platform. This refers to the change in the pitch angle of the floating platform.

[0056] Will Substituting the values ​​into the ballast response model, the effects of each candidate inflow / outflow combination on draft, heel, trim, and mooring chain tension are predicted, and a combination that satisfies the constraints and makes... Minimum set of inlet and outlet control quantities ;

[0057] The constraints are:

[0058]

[0059]

[0060] in, For the first The maximum allowable water volume for each ballast tank; For the first The maximum flow rate of the pump and valve assembly corresponding to each ballast tank; To control the cycle; , The first The allowable lower and upper limits of tension for root mooring anchor chains; , These are the maximum allowable tilt and longitudinal tilt limits for floating platforms, respectively. The maximum allowable descent speed; when calculated... If the above constraints are exceeded, the inflow and outflow will be executed according to the limited range, and data will be collected and calculated again in the next control cycle.

[0061] As a preferred option, the six mooring chains are arranged circumferentially in groups of two or three. The average tension of each group of mooring chains is calculated, and then the tension deviation between groups and the tension deviation within groups are calculated. The average tension of a group of mooring anchor chains is written as:

[0062]

[0063] Intergroup tension deviation and intragroup tension deviation are written as follows:

[0064]

[0065]

[0066] in, For the first The average tension of the two mooring anchor chains. , These are the tensions of the two mooring anchor chains in the j-th group, respectively; Pretension for the target; For the first Inter-group tension deviation of mooring anchor chains; For the first Tension deviation within the mooring chain group;

[0067] In step S6, when tensioning the mooring anchor chain, the tensioning sequence is output according to the principle of first between groups, then within groups, first low tension, then high tension, and small steps with multiple closed-loop corrections.

[0068] No. The recommended chain allowance for root mooring anchor chains is written as:

[0069]

[0070] in, For the first Recommended chain allowance for root mooring anchor chains; , , For control coefficients; A suppression term introduced for the rate of change of tension or the change of platform attitude; Calculate using the following formula:

[0071]

[0072] in, , , The weight coefficient for the suppression term; For the first Rate of change of anchor chain tension at root mooring;

[0073] When the tension of a mooring chain changes too rapidly, the tension of adjacent mooring chains is abnormal, or the platform attitude changes beyond the limit, it can lead to... When the tension increases, reduce the recommended chain extension / retraction amount of the mooring anchor chain or suspend tensioning.

[0074] As a preferred option, after the dynamic submarine cable is laid at the designed location, step S2 is performed on the work vessel: the wind turbine end of the dynamic submarine cable is inserted into the bottom of the mooring connector and then pushed out from the middle upwards, leaving room for the distance to the high-voltage switchgear and the redundant length during normal operation, and coiled on the top of the mooring connector; a hoist is installed on each of the three auxiliary lugs of the mooring connector.

[0075] As a preferred option, in step S3, the work vessel lowers the mooring connector with the connected dynamic submarine cable onto the sea surface, then connects the hoists on the three auxiliary lugs of the mooring connector to the ends of the two mooring anchor chains in the corresponding directions, tightens the hoists, and pulls the connecting shackles at the ends of the mooring anchor chains closer to the diver or ROV to install the connecting shackles to the position of the main lugs; when all six mooring anchor chains are connected to the main lugs, the hoists connecting the mooring anchor chains and auxiliary lugs are slowly loosened, and then removed after complete relaxation.

[0076] The downwind floating wind turbine outer turret suspended single-point mooring system includes mooring connectors, mooring anchor chains, off-line buoys, quick couplings, on-line tensioners, connecting shackles, float end connectors, upwind buoys, outer turret platform, mooring bearings, and outer turret cylinder;

[0077] The mooring connector has main lugs and auxiliary lugs distributed around its periphery, which are used to connect the mooring anchor chain to the mooring connector via a connecting shackle. The top of the mooring connector is provided with a top guide tube.

[0078] Offline buoys are hollow components with inlet / outlet and outlet / vent, which are connected to mooring chains via quick couplings to provide adjustable buoyancy to the ends of the mooring chains.

[0079] The floating body end connector is installed on the floating platform. The floating body end connector, the upwind float, the outer turret platform, and the outer turret are connected in sequence to form a whole. The floating body end connector is equipped with a ballast tank. The floating platform can be submerged or floated by filling and dewatering the ballast tank. The upwind float is used to provide stability and restoring torque for the floating platform when the unit is running.

[0080] The outer ring of the mooring bearing is bolted to the bottom of the outer turret platform and fixed relative to the floating platform. The inner ring can be bolted to the mooring connector. A side guide cylinder is provided at the bottom middle of the mooring bearing. The side guide cylinder and the top guide cylinder are guided by guide strips.

[0081] Online tensioners are installed on each mooring anchor chain. After the mooring connectors and mooring bearings are connected and installed, the tension of the mooring anchor chains is adjusted by tightening to keep the floating platform on the sea surface.

[0082] As a preferred embodiment, it also includes a mooring chain tension sensor, a float pressure or level detection interface, a coaxial deviation detection unit, a ballast pump valve control unit, and a float inlet / outlet control unit;

[0083] The mooring chain tension sensor is installed near the connection point between the mooring chain and the main lug on the side wall of the mooring connector. It is used to detect the actual tension of each mooring chain at the connection point and to serve as the data source for mooring chain tension balance control.

[0084] The buoy pressure or liquid level detection interface is set on the offline buoy, connected to the pressure / liquid level sensor inside the offline buoy, and connected to the temporary pipeline of the work vessel. It is used to detect the internal pressure or liquid level of the offline buoy in order to adjust the buoyancy of the offline buoy.

[0085] The coaxial deviation detection unit is used to detect the horizontal offset, angular deviation or distance deviation between the guide cylinder of the mooring bearing and the top guide cylinder of the mooring connector. It employs one or more of the following methods: visual recognition, laser ranging, RTK positioning, proximity sensor or mechanical limit detection.

[0086] Ballast pump valve control unit, used to control the inflow and outflow of ballast tanks according to the target ballast volume;

[0087] The buoy inlet and outlet control unit is used to perform water intake, drainage, or pressure testing operations on the offline buoy through temporary pipelines or field valve groups on the work vessel.

[0088] Compared with existing traditional single-point mooring technology, this invention achieves comprehensive improvement in terms of construction efficiency, engineering cost, system reliability, operation and maintenance convenience, and sea condition adaptability through four core innovations: external turret suspension structure, split-type rapid reconnection, platform separability and reusability, and surface maintenance.

[0089] In summary, the present invention has the following advantages:

[0090] (1) Significantly shorten the offshore construction cycle and greatly reduce the cost of ships, machinery and time.

[0091] This invention employs a separate prefabrication and parallel construction mode for the mooring system and floating platform: mooring anchor chains, dynamic submarine cables, and mooring connectors can be pre-assembled at sea and floated for standby. This process does not interfere with the assembly, hoisting, and commissioning of the floating platform, achieving parallel operation. Once the floating platform is towed into position, it only needs to be ballasted and submerged to complete a one-time rapid docking with the mooring system. This reduces the sea mooring return period from the traditional 15 days to less than 2 days, significantly reducing the usage time and rental costs of large crane vessels and multiple tugboats, significantly improving the utilization rate of the offshore construction window, and reducing the overall project cost.

[0092] (2) Significantly reduce the technical requirements for mooring bearings, enabling them to be maintained and replaced on-site.

[0093] Traditional single-point mooring bearings are submerged underwater for extended periods, requiring extremely high levels of watertightness and corrosion resistance, and are very expensive. After a failure, they must be towed back to port for repair. This invention employs an external turret suspension design, preventing the mooring bearing from directly bearing the pressure of deep water and prolonged submersion, significantly reducing sealing difficulty and manufacturing costs. Furthermore, maintenance and replacement of the mooring bearings can be completed on-site at sea without disassembling the entire mooring chain, saving the cost and time of towing back to port and greatly improving system availability and lifecycle economics.

[0094] (3) To realize the maintenance of mooring anchor chains and monitoring equipment on water, thereby improving safety and convenience.

[0095] This invention elevates the mooring connector and the end of the mooring chain above the water surface, forming a suspended working interface. The condition of the mooring chain can be directly inspected visually, eliminating the need for frequent ROV or diving operations. Key components such as the end of the mooring chain, mooring sensors, and connecting shackles are all within reach above water, allowing for direct maintenance, replacement, and adjustment via a top crane. This completely eliminates the risks of underwater operations, reduces maintenance difficulty and costs, and improves the level of monitoring and management throughout the entire lifecycle.

[0096] (4) Enables rapid separation of floating platforms from mooring systems, supporting relocation and reuse.

[0097] Traditional single-point mooring requires dismantling and repositioning mooring chains one by one during platform relocation or maintenance. This process is complex, risky, and time-consuming. This invention provides a reversible separation solution: simply adjust the online tensioner to loosen the mooring chain, install the offline buoy to raise the end of the mooring chain, and submerge the platform under ballast to detach the mooring bearing and connectors to achieve safe separation of the platform from the mooring system. When repositioning, the connection can be quickly restored without the need to repeatedly lay mooring chains and submarine cables, greatly improving the flexibility of platform relocation, maintenance, and reuse.

[0098] (5) It retains the passive wind-fighting advantage of single-point mooring and is suitable for harsh sea conditions in deep sea.

[0099] This invention fully retains the technical advantages of combining downwind direction and single-point mooring. The unit can passively yaw 360° to align with the wind without a complex active yaw system, simplifying the control strategy and reducing the failure rate. At the same time, it effectively avoids blade sweeping to the tower, reduces the fatigue load of the whole machine, and improves the ability to resist typhoons and strong waves. It is more suitable for the development needs of lightweight, high reliability and long service life of wind turbines in deep-sea, high-water-depth, high-sea-state, and high-power wind turbines.

[0100] (6) The system is modular, versatile, and easy to promote in the industry.

[0101] This invention combines standard ship and wind power components, resulting in a simple structure, low manufacturing difficulty, and strong adaptability. It can be directly applied to various floating foundations such as semi-submersible, barge, tension leg, and column types. It is compatible with mature supply chain products such as steel mooring anchor chains, composite material mooring anchor chains, and conventional dynamic submarine cables. No special equipment needs to be customized, making it valuable for industrial replication and large-scale promotion.

[0102] (7) Reduce the high-risk window period of no mooring and improve unit safety.

[0103] In traditional construction methods, floating platforms are often left unmoored in open sea conditions, making them highly susceptible to the effects of wind, waves, and currents, and posing a high risk of displacement. This invention significantly reduces the time the platform spends in open sea, greatly minimizing construction risks during extreme sea conditions such as typhoons, gales, and large waves, and enhancing the safety and controllability of the entire unit installation process. Attached Figure Description

[0104] Figure 1 This is a front view of the downwind floating wind turbine external turret suspended single-point mooring system of the present invention.

[0105] Figure 2 This is a perspective view of the downwind floating wind turbine external turret suspended single-point mooring system of the present invention.

[0106] Figure 3 This is a side view of the downwind floating wind turbine external turret suspended single-point mooring system of the present invention.

[0107] Figure 4 This is a front view of the invention before installation.

[0108] Figure 5 This is a front view of the present invention during mooring reconnection installation.

[0109] Figure 6 This is a front view of the completed installation of the present invention.

[0110] Figure 7 This is a front view of the invention in normal operation.

[0111] Figure 8 Block diagram for the installation control system.

[0112] Figure 9 Installation control flowchart.

[0113] Figure 10 This is a schematic diagram showing the layout of key testing points and temporary pipelines.

[0114] Among them, 1 is the mooring connector; 2 is the mooring anchor chain; 3 is the off-line buoy; 4 is the quick connector; 5 is the online tensioner; 6 is the connecting shackle; 7 is the main lug; 8 is the auxiliary lug; 9 is the dynamic submarine cable; 10 is the float end connector; 11 is the upwind buoy; 12 is the outer turret platform; 13 is the mooring bearing; 14 is the outer turret tube; 15 is the high-voltage slip ring; 16 is the high-voltage switchgear; 17 is the crane; and 18 is the central controller. Detailed Implementation

[0115] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0116] Example 1

[0117] like Figures 4-7 As shown, the specific process of the levitated single-point mooring method for the outer turret of a downwind floating wind turbine is as follows:

[0118] 1) After the six mooring anchor chains are laid in the designed positions by the laying operation vessel, the ends of the mooring anchor chains are connected to the non-lined buoys that can be inflated and deflated via quick couplings, so that the ends of the six mooring anchor chains float near the sea surface.

[0119] 2) After the dynamic submarine cable is laid at the designed location by the cable laying vessel, the wind turbine end of the dynamic submarine cable passes through the waterproof sealing joint at the bottom of the mooring connector on the vessel, and emerges from the middle upwards, leaving a suitable distance and some redundant length for normal operation to the high-voltage switchgear, and is coiled on top of the mooring connector. Each of the three auxiliary lugs of the mooring connector is equipped with a hoist.

[0120] 3) The work vessel lowers the mooring connector with the connected dynamic submarine cable to the sea surface. Then, it connects the hoists on the three auxiliary lugs of the mooring connector to the ends of the two corresponding mooring chains. The hoists are tightened, and the connecting shackles at the ends of the mooring chains are pulled closer to the diver or ROV for easy installation onto the main lugs. Once all six mooring chains are connected to the main lugs, the hoists connecting the mooring chains to the auxiliary lugs are slowly released. After complete relaxation, the connection is removed.

[0121] 4) After the floating platform is towed to the installation position by tugboats, the tugboats are used to adjust it so that the mooring bearings and mooring connections are approximately coaxial. Figure 4 Then, the floating platform is ballasted and submerged. During this process, the tugboat needs to continuously adjust the position of the mooring bearing to keep it coaxial with the mooring connector. Simultaneously, construction personnel are deployed to the top of the mooring connector to ensure the flange mating surface is sealed and waterproofed. The end of the dynamic submarine cable coiled on the mooring connector is then lifted and passed through the top guide cylinder of the mooring bearing. Ballasting submersion continues. When the top guide cylinder of the mooring connector engages with the guide strip on the side guide cylinder of the mooring bearing, multiple locating pins are passed through the bolt holes of the inner ring of the mooring bearing and aligned with the bolt holes on the mooring connector. Finally, the platform is submerged to a suitable position, ensuring the mooring bearing and the connecting flange of the mooring connector are tightly fitted, and the bolts are installed and tightened. After docking is completed... Figure 5 .

[0122] 5) Slowly replace the gas inside the six off-line buoys with water in sequence, so that the six mooring chains gradually return to their normal catenary position and attitude. Then, use the ROV to disconnect the quick coupling, separate the mooring chains from the off-line buoys, and gradually drain the water from the off-line buoys to make them float to the surface for recovery.

[0123] 6) Use the work vessel to tension the online tensioners sequentially, thus tensioning the mooring anchor chain. After completion, as follows... Figure 6 .

[0124] 7) Adjust the load on the floating platform to the normal operating draft of the unit, such as... Figure 7 The mooring connector and the end of the mooring anchor chain are lifted out of the water to make them float, and then the dynamic submarine cable is connected to the high-voltage switch cabinet and the high-voltage slip ring.

[0125] 8) Finally, a tugboat is used to carry the floating platform around the mooring point for a rotation test to check for interference, smooth rotation, and the availability of single-point mooring.

[0126] like Figures 8-10As shown, the overall control logic for steps 4) to 7) above is as follows: the central controller operates according to eight states: S4.4.1: floating standby, S4.2: coarse alignment, S4.3: controlled descent, S4.4: guide engagement, S4.5: flange tightening, S5: buoy unloading, S6: mooring chain tension balancing, and S7: operational draft adjustment. The central controller switches between these states based on platform draft, platform attitude, mooring connection height, offline buoy status, mooring chain tension, coaxial deviation, and environmental conditions. It then outputs ballast tank inflow / displacement, offline buoy inflow / displacement, target mooring chain tension, recommended chain extension / retraction amount, and alarm protection commands, as detailed below.

[0127] S4.1: Floating Standby. After the mooring anchor chain and mooring connector are pre-laid, the central controller or field control terminal reads data such as the tension of the mooring anchor chain, the pressure or level of the buoy, and the attitude of the mooring connector. Through offline buoy water inlet and outlet, the mooring connector is kept at the target exposed height and basically horizontal attitude.

[0128] S4.2: Coarse Alignment. After the floating platform is towed to the vicinity of the aircraft position, the central controller outputs a coarse alignment prompt to the tugboat, dynamic positioning equipment, or on-site personnel based on the platform position, the attitude of the outer turret platform, and the coaxial deviation detection results, so that the mooring bearing guide cylinder is within the allowable range above the top guide cylinder of the mooring connector.

[0129] S4.3: Controlled Descent. The central controller controls the ballast pump valve assembly to introduce water into the ballast tank or conditioning tank, causing the platform to descend at a preset speed. Simultaneously, the controller monitors the platform's list, trim, draft, coaxial deviation, and the tension of each mooring chain. If any parameter exceeds the allowable range, the descent is paused or the platform is surfaced for resetting.

[0130] S4.4: Guide engagement. When the coaxial deviation meets the guide engagement condition, the central controller reduces the diving speed, so that the guide cylinder on the mooring bearing side gradually engages with the guide cylinder on the top of the mooring connector, and maintains the stability of the platform attitude during the stage of guide bar contact or locating pin alignment.

[0131] S4.5: Flange tightening. After the guide engagement is complete, the central controller maintains the ballast state, and the construction personnel complete the installation of the positioning pins, bolts, and sealing structure. The main criteria for this stage are attitude stability and controlled rate of change of mooring chain tension.

[0132] S5: Float unloading. After the flange connection is completed, the central controller controls or instructs the offline float to gradually enter water according to the preset sequence, so that the mooring anchor chain smoothly transitions from the temporary raised state to the designed catenary state. After the tension change rate meets the requirements, the quick coupling is disconnected and the float is retrieved by ROV or manually.

[0133] S6: Mooring chain tension equalization. The central controller reads data from the mooring chain tension sensor installed near the connection point between the mooring chain and the main lug on the side wall of the mooring connector, calculates the tension deviation between groups and the tension deviation within groups, and outputs the target tension, recommended chain take-up and release amount, and tensioning sequence.

[0134] S7: Draft Adjustment. After the mooring chain tension is balanced, the central controller adjusts the platform to the normal operating draft and keeps the mooring connectors and mooring chain ends in the maintenance position above or near the water surface.

[0135] Status input: The center coordinates of the side guide tubes of the floating platform are as follows: , The center coordinates of the top guide tube of the mooring connector are marked as , The angle of the side guide cylinder axis is denoted as The angle of the axis of the top guide cylinder of the mooring connector is denoted as The tilt angle of a floating platform is denoted as... The tilt angle of the floating platform is denoted as ;No. The anchor chain tension of the root mooring is denoted as The reference tension is denoted as The diving speed of the floating platform is denoted as... ;

[0136] Coaxial deviation is calculated as follows:

[0137]

[0138]

[0139]

[0140]

[0141] in, , This refers to the deviation of the centers of the side guide cylinder and the top guide cylinder in the horizontal plane; This refers to the angular deviation between the axes of the side guide cylinder and the top guide cylinder; The sum of squares of the horizontal deviations is used to determine whether entering the guide engagement stage is permitted;

[0142] Controlled descent phase: Using coaxial deviation, platform attitude, ballast tank level, and anchor chain tension as inputs, calculate the inflow and outflow control parameters for each ballast tank. The objective function is written as:

[0143]

[0144] in, The objective function for controlled descent is... to These are the weighting coefficients. To correspond to the reference tension of the mooring anchor chain at this stage, The platform's diving speed; when the coaxial deviation, platform attitude, or mooring anchor chain tension change rate exceeds the preset threshold, ballast water intake is suspended, the current draft is maintained, or the floating platform is controlled to rise to a safe height and then re-aligned.

[0145] To transform the objective function into the inflow and outflow control quantities for each ballast tank, the central controller uses the current cycle inflow and outflow increment of each ballast tank or ballast adjustment tank as the control variable. For m ballast tanks with adjustable water volumes, the current water volume of the k-th ballast tank is V. k The increase in water inflow and outflow during this cycle is ΔV k Then the control variable is represented as:

[0146] The central controller establishes a ballast response model based on the overall layout of the floating platform, the location of each ballast tank, pump and valve flow rates, and on-site calibration data. The ballast response model is obtained through hydrostatic calculations, tank tests, numerical simulations, or on-site pressure testing and calibration, and is stored in the form of a response coefficient matrix or lookup table. The simplified expression of the ballast response model is:

[0147]

[0148]

[0149] in, Forecast response volume for this period; This is the ballast response coefficient matrix; This refers to the change in draft of the floating platform; For the first The change in tension of the mooring chain; This represents the change in the tilt angle of the floating platform. This refers to the change in the pitch angle of the floating platform.

[0150] Will Substituting the values ​​into the ballast response model, the effects of each candidate inflow / outflow combination on draft, heel, trim, and mooring chain tension are predicted, and a combination that satisfies the constraints and makes... Minimum set of inlet and outlet control quantities ;

[0151] In a preferred embodiment, the water inflow and outflow control amounts of each ballast tank satisfy the following constraints:

[0152]

[0153]

[0154] in, For the first The maximum allowable water volume for each ballast tank; For the first The maximum flow rate of the pump and valve assembly corresponding to each ballast tank; To control the cycle; , The first The allowable lower and upper limits of tension for root mooring anchor chains; , These are the maximum allowable tilt and longitudinal tilt limits for floating platforms, respectively. To allow an upper limit on the descent speed. Preferably, the control cycle... Take 5s to 60s; single inflow / outflow increment The allowable deviation shall not exceed 1% to 10% of the effective volume of the corresponding ballast tank; the upper limit for platform roll and pitch shall be 1° to 3°; the allowable value for coaxial horizontal deviation shall be 0.2m to 1.0m; the allowable value for guide tube axis angle deviation shall be 0.5° to 3°; the upper limit for platform diving speed shall be 0.02m / min to 0.20m / min; the allowable value for anchor chain tension deviation shall be 5% to 15% of the target tension. When calculated... When the above constraints are exceeded, the central controller will execute the water inflow and outflow according to the limited flow rate, and will collect data and recalculate in the next control cycle.

[0155] Offline buoyancy adjustment: The water level inside the offline buoy is obtained through pressure or level detection interfaces, and water inlet and outlet are carried out through temporary pipelines built by the work vessel; The effective buoyancy of an offline pontoon is estimated using the following formula:

[0156]

[0157] in, For the first Effective buoyancy of an offline pontoon; The density of seawater; It is the acceleration due to gravity; For the first Total internal volume of each offline pontoon; For the first The volume of water entering the non-online pontoon; For the first The weight of the offline pontoon itself;

[0158] Based on the target exposure height, attitude deviation, and mooring chain tension deviation of the mooring connectors, the recommended inflow and outflow rates for each off-line buoy are given, specifically: when the... The change in water inlet volume for each offline pontoon is When the effective buoyancy changes, it is expressed as:

[0159]

[0160] Based on the correspondence between the water inflow volume and effective buoyancy of each offline buoy, and according to the mass of the mooring connector, the position of the buoy center, the arrangement of the main lugs, the angle of entry of the mooring anchor chain, the connection position of the offline buoy, and the field calibration data, a static balance or calibration model is established between the water inflow and outflow of the offline buoy and the exposed height, attitude deviation, and tension change of the mooring anchor chain. The static balance or calibration model is written as follows:

[0161]

[0162]

[0163] in, This represents the predicted change in the condition of the mooring connections for this period. This is the non-online pontoon adjustment response coefficient matrix; This refers to the change in the exposed height of the mooring connection. , These represent the changes in the lateral and longitudinal attitude angles of the mooring connectors, respectively. For the first The change in tension of the mooring chain; This is a vector composed of the changes in the water inlet volume of each offline pontoon;

[0164] Based on the height of the target exposure Allowable attitude deviation and target tension Based on this, the recommended water inflow and outflow of each offline buoy is calculated step by step. After execution, the buoy pressure or liquid level, mooring connection attitude and mooring anchor chain tension data are reread until the exposed height, attitude and tension are within the set range.

[0165]

[0166]

[0167] in, For the first The maximum flow rate of a non-online temporary inlet / outlet pipeline or pump valve for a float; This is the current exposed height of the mooring connector; Allowable deviation for exposed height; , These represent the upper limit of the allowable attitude angle of the mooring connection. Preferably, the offline buoy control cycle is between 10s and 120s; the single inflow / outflow volume change... Not exceeding 1% to 10% of the total internal volume of the corresponding pontoon; target exposed height of mooring connectors. The allowable deviation for exposed height is 0.3m to 3.0m. The allowable upper limit for the attitude angle of the mooring connector is 1° to 5°, ranging from 0.05m to 0.30m. When the anchor chain tension is balanced, the tension deviation of the anchor chains in the same or different groups should preferably be controlled within the target tension range. The range is between 5% and 15%.

[0168] Mooring chain tension balance control: Six mooring chains are arranged circumferentially in groups of two or three. The average tension of each group of mooring chains is calculated, and then the tension deviation between groups and the tension deviation within groups are calculated. The average tension of a group of mooring anchor chains is written as:

[0169]

[0170] Intergroup tension deviation and intragroup tension deviation are written as follows:

[0171]

[0172]

[0173] in, For the first The average tension of the two mooring anchor chains. , These are the tensions of the two mooring anchor chains in the j-th group, respectively; Pretension for the target; For the first Inter-group tension deviation of mooring anchor chains; For the first Tension deviation within the mooring chain group;

[0174] In step S6, when tensioning the mooring anchor chain, the tensioning sequence is output according to the principle of first between groups, then within groups, first low tension, then high tension, and small steps with multiple closed-loop corrections.

[0175] No. The recommended chain allowance for root mooring anchor chains is written as:

[0176]

[0177] in, For the first Recommended chain allowance for root mooring anchor chains; , , For control coefficients; A suppression term introduced for the rate of change of tension or the change of platform attitude; Calculate using the following formula:

[0178]

[0179] in, , , The weight coefficient for the suppression term; For the first Rate of change of anchor chain tension at root mooring;

[0180] When the tension of a mooring chain changes too rapidly, the tension of adjacent mooring chains is abnormal, or the platform attitude changes beyond the limit, it can lead to... When the tension increases, reduce the recommended chain extension / retraction amount of the mooring anchor chain or suspend tensioning.

[0181] Tensioning Execution Method: When the tensioning execution unit lacks direct electrical control capability, the central controller outputs the target tension, recommended chain extension / retraction amount, and tensioning sequence. After confirmation by the operators, this is executed via the winch of the work vessel, hydraulic tensioning device, or chain stopper in conjunction with the traction equipment. After each tensioning, the central controller reads the new mooring chain tension data and performs the next round of correction until the tension of each mooring chain enters the preset equilibrium range.

[0182] Abnormal protection logic: When the tension of any mooring anchor chain exceeds the upper limit or falls below the lower limit, the tension difference between mooring anchor chains in the same or different groups exceeds the threshold, the platform's roll or pitch exceeds the threshold, the coaxial deviation exceeds the allowable value, or the environmental wind, waves and currents exceed the allowable installation conditions, the central controller enters the abnormal protection state, suspends water intake or stops tensioning, and outputs instructions to maintain the current draft, float and reset, realign, or stop the installation.

[0183] This invention improves and optimizes the traditional single-point mooring system by: (1) adopting a separate design for the structure and construction of the mooring connector and the mooring bearing. The laying of the mooring anchor chain and the installation of the mooring connector do not interfere with the operation of the floating platform hoisting and can be carried out independently. After installation, the mooring connector can float at sea and wait for docking. The large construction vessel can leave the site after finishing its work. After the floating platform is towed to the position, since the mooring anchor chain and submarine cable have been laid and reconnected, the overall docking process can be completed in just 2 days, which greatly reduces the probability of the floating platform encountering typhoons and large waves during the mooring vacuum period at sea, and significantly reduces the construction and vessel rental costs; (2) when the floating platform needs to be separated, it is only necessary to adjust the online tensioner, install the offline buoy to lift the mooring anchor chain, ballast the floating platform to the appropriate draft, and separate the mooring bearing and the mooring connector. Although the offline buoy installation is added, compared with the traditional solution, it saves the step of removing the mooring anchor chain one by one and positioning it, which is more convenient. Meanwhile, the non-online buoy using composite materials can adjust the position of the mooring anchor chain by reducing its own volume, so as to reduce the impact of ocean currents on the buoy and the mooring anchor chain. When needed, it can be inflated to continue to function without disassembly; (3) The mooring bearing does not need to be in direct contact with seawater, but is only in the splash zone, which greatly reduces the requirements for waterproof sealing. In case of failure and replacement, it is only necessary to separate the mooring connector and the mooring bearing, and then float the floating platform to the bottom of the outer turret platform to disassemble and recycle the old bearing and replace and install the new bearing; (4) The end of the mooring anchor chain is located on the water. By visually observing the state of the end of the mooring anchor chain, the state of the mooring anchor chain can be roughly understood, which greatly reduces the frequency of using ROV. For the mooring anchor chain end and the mooring monitoring sensor installed at the mooring anchor chain end, the maintenance work surface is also on the water. The crane on the outer turret can be used to hoist people to the corresponding work surface for maintenance; (5) It has strong expandability and can be used for various floating platforms such as semi-submersible, tension leg, and barge type, and is compatible with steel / composite mooring anchor chains and dynamic submarine cable systems.

[0184] Example 2

[0185] like Figures 1-3 As shown, the downwind floating wind turbine outer turret suspended single-point mooring system can be used to implement the mooring method in Embodiment 1. The system includes mooring connectors, mooring anchor chains, offline buoys, quick couplings, connecting shackles, main lugs, auxiliary lugs, dynamic submarine cables, float end connectors, upwind buoys, outer turret platform, mooring bearings, outer turret cylinder, high-voltage slip rings, high-voltage switchgear, cranes, central controllers, mooring anchor chain tension sensors, buoy pressure or liquid level detection interfaces, coaxial deviation detection units, ballast pump valve control units, and buoy inlet and outlet control units.

[0186] The mooring connector is a transition piece that connects the mooring anchor chain and the mooring bearing. The upper ends of all the mooring anchor chains in the mooring system are connected to the side of the mooring connector via connecting shackles and main lugs. The mooring connector is then bolted to the mooring bearing through the blind hole at the top. The connecting flange has a sealing and waterproofing measure. The top of the mooring connector has a guide cylinder, and the outside of the guide cylinder has a guide strip to facilitate docking with the mooring bearing.

[0187] Mooring chains, made entirely of steel or a combination of steel and composite materials, form the main structure of a mooring system and serve to anchor floating platforms to the sea. They are covered with sacrificial anode blocks to inhibit corrosion.

[0188] Offline buoys are metal or composite material balls located near mooring connections that provide buoyancy to the mooring anchor chains. Their buoyancy can be changed by pumping water into or out of the buoys. They are connected to the mooring anchor chains via quick couplings.

[0189] Quick couplings are components used to connect mooring anchor chains and off-line buoys, and can be connected and disconnected via ROV;

[0190] An online tensioner is a tensioning device installed at one end of a mooring anchor chain or implemented by a work vessel, a hydraulic tensioning device, a chain stopper, and a traction device. The mooring anchor chain is tensioned by operating the online tensioner or by being pulled by external tensioning equipment.

[0191] A connecting shackle is a device at the end of a mooring chain used to connect the mooring chain and the mooring connector, allowing for quick assembly and disassembly.

[0192] The main lug is a lug structure that is ring-mounted on the side wall of the mooring connector and is used to connect the connecting shackle to the mooring connector;

[0193] The auxiliary lug is located above the main lug and has a similar structure to the main lug. It is used to assist in installing the connecting shackle to the main lug during the installation of the mooring anchor chain.

[0194] Dynamic submarine cables are power collection lines that exchange power and communication between floating wind turbines and substations. Most of them are buried in the seabed and connected to the substation or other units. The rest of the cable is a slowly rising wave shape that passes through the mooring connector and mooring bearing and connects to the high-voltage switchgear and high-voltage slip ring.

[0195] The end connector of the floating body is a steel casting that connects the upwind pontoon to the floating platform. It contains a ballast tank and can submerge / surface the floating platform by pumping / draining water. Its surface is also equipped with lugs for tugboat cable attachment. The unit is completely underwater during operation.

[0196] The upwind pontoon, a steel casting, connects the outer turret platform to the floating platform. When the unit is running, part of it is above water, providing stability and restoring torque to the floating platform.

[0197] The outer turret platform, a steel casting, is a crucial location for the installation of the single-point mooring system, connecting the mooring system to the floating platform.

[0198] The mooring bearing is a bearing installed inside the outer turret platform to enable the floating platform to rotate 360° and moor at a single point. The outer ring of the bearing is connected to the outer turret platform by bolts, and the inner ring is connected to the mooring connector by bolts. There is a guide cylinder at the top of the middle of the mooring bearing, and there are guide strips on the inside of the guide cylinder to facilitate docking and installation with the mooring connector.

[0199] The outer turret is a welded component with three internal layers, providing a closed operating space for the internal high-voltage slip rings, high-voltage switchgear, and mooring bearings.

[0200] High-voltage slip rings, installed inside the outer turret, are key conductive components of single-point moored rotating equipment. They are mainly used to achieve continuous and reliable power and communication transmission between the stationary end and the rotating end under high-voltage and high-current conditions.

[0201] High-voltage switchgear, installed inside the outer slewing tower, is a core set of equipment in the power distribution system, used for receiving, distributing and controlling high-voltage electrical energy. It is connected to the high-voltage slip ring via a high-voltage cable.

[0202] The crane, installed on the top of the outer turret platform, plays an auxiliary role in mooring re-engagement and mooring system maintenance.

[0203] The central controller can be an existing main control system of the wind turbine or a separately installed controller. It is used to receive data such as platform attitude, draft, ballast tank level, mooring chain tension, offline buoy pressure or level, coaxial deviation and environmental conditions, and output ballast tank inflow and outflow, buoy inflow and outflow, target mooring chain tension or recommended chain extension and retraction amount.

[0204] The mooring chain tension sensor is installed near the connection point between the mooring chain and the main lug on the side wall of the mooring connector. It is used to detect the actual tension of each mooring chain at the connection point and to serve as the data source for mooring chain tension balance control.

[0205] The buoy pressure or level detection interface (P / L interface) is set on the offline buoy and connected to the pressure / level sensor inside the offline buoy. It can be connected to the temporary pipeline of the work vessel to detect the internal pressure or level of the offline buoy and adjust the buoyancy of the offline buoy in conjunction with the inlet and outlet interfaces.

[0206] The coaxial deviation detection unit is used to detect the horizontal offset, angular deviation or distance deviation between the guide cylinder of the mooring bearing and the top guide cylinder of the mooring connector. It can use one or more of the following methods: visual recognition, laser ranging, RTK positioning, proximity sensor or mechanical limit detection.

[0207] Ballast pump valve control unit is used to control the inflow and outflow of ballast tanks or ballast bins according to the target ballast volume output by the central controller;

[0208] The buoy inlet and outlet control unit is used to perform water intake, drainage, or pressure testing operations on the off-line buoy through temporary pipelines on the work vessel or on-site valve groups.

[0209] The system also includes tilt sensors, draft sensors, ballast tank level sensors, and environmental and positioning data interfaces.

[0210] The above embodiments are preferred embodiments of the invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for single-point mooring of the outer turret of a downwind floating wind turbine, characterized in that: Includes the following steps, S1, Pre-laying of mooring anchor chains: Six mooring anchor chains are laid by positioning the work vessel. Each mooring anchor chain is connected to an offline buoy that can be inflated and deflated via a quick connector. The offline buoy keeps the ends of the six mooring anchor chains floating on the sea surface. S2, Connect the dynamic submarine cable: Insert the dynamic submarine cable into the mooring connector, pass it out from the middle of the mooring connector, and reserve a redundant length. S3, lowering the mooring connector: lower the mooring connector with the connected dynamic submarine cable to the sea surface, and connect the mooring anchor chain to the main lug of the mooring connector in sequence; S4, Platform Submersion and Docking: The tugboat tows the floating platform to the installation position, uses the tugboat to adjust the floating platform to align with the mooring connector, applies ballast to the floating platform for submersion, and during the ballast submersion process, the tugboat continuously adjusts the position of the floating platform to keep it aligned with the mooring connector, and docks the floating platform with the mooring connector. S5, Offline Float Unloading and Recovery: The six offline floats are filled with water to replace some or all of the gas inside the floats with water. After the six mooring chains gradually return to their catenary positions, the quick couplings are released to separate the mooring chains from the offline floats. Then, the water inside the offline floats is gradually emptied to allow them to float to the surface for recovery. S6, Mooring chain tensioning: The mooring chain is tensioned using an online tensioner; S7, Platform Load Adjustment: By adjusting the load on the floating platform to the normal operating draft of the unit, the mooring connector and the end of the mooring anchor chain are lifted out of the water to make them suspend, and then the dynamic submarine cable is connected to the high-voltage switch cabinet and high-voltage slip ring on the floating platform. S8, Rotation Test: Use a tugboat to carry the floating platform around the mooring point to conduct a rotation test to check for interference, smooth rotation, and the availability of single-point mooring.

2. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 1, characterized in that: After the mooring connector is lowered, step S4.1 is performed first: floating standby: acquiring the mooring anchor chain tension, offline buoy pressure or liquid level, and mooring connector attitude data, and adjusting the water intake and air volume in each offline buoy to keep the mooring connector at the target exposed height and basic horizontal attitude.

3. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 2, characterized in that: The water level inside the offline buoy is obtained through pressure or level detection interfaces, and water inlet and outlet are carried out via temporary pipelines constructed by the work vessel; The effective buoyancy of an offline pontoon is estimated using the following formula: ； in, For the first Effective buoyancy of an offline pontoon; The density of seawater; It is the acceleration due to gravity; For the first Total internal volume of each offline pontoon; For the first The volume of water entering the non-online pontoon; For the first The weight of the offline pontoon itself; When the The change in water inlet volume for each offline pontoon is When the effective buoyancy changes, it is expressed as: ； Based on the correspondence between the water inflow volume and effective buoyancy of each offline buoy, and according to the mass of the mooring connector, the position of the buoy center, the arrangement of the main lugs, the angle of entry of the mooring anchor chain, the connection position of the offline buoy, and the field calibration data, a static balance or calibration model is established between the water inflow and outflow of the offline buoy and the exposed height, attitude deviation, and tension change of the mooring anchor chain. The static balance or calibration model is written as follows: ； ； in, This represents the predicted change in the condition of the mooring connections for this period. This is the non-online pontoon adjustment response coefficient matrix; This refers to the change in the exposed height of the mooring connection. , These represent the changes in the lateral and longitudinal attitude angles of the mooring connectors, respectively. For the first The change in tension of the mooring chain; This is a vector composed of the changes in the water inlet volume of each offline pontoon; Based on the height of the target exposure Allowable attitude deviation and target tension Based on this, the recommended water inflow and outflow of each offline buoy is calculated step by step. After execution, the buoy pressure or liquid level, mooring connection attitude and mooring anchor chain tension data are reread until the exposed height, attitude and tension are within the set range. ； ； in, For the first The maximum flow rate of a non-online temporary inlet / outlet pipeline or pump valve for a float; This is the current exposed height of the mooring connector; Allowable deviation for exposed height; , These are the upper limits of the allowable attitude angles of the mooring connectors.

4. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 2, characterized in that: The floating platform is equipped with a mooring bearing for docking with the mooring connector. The mooring bearing has a side guide cylinder, and the mooring connector has a top guide cylinder. The top and side guide cylinders are guided by guide strips and positioned by locating pins. The platform's submersion and docking process specifically includes the following steps: S4.2, Coarse Alignment: After the tugboat tows the floating platform to the vicinity of the installation position, based on the detection results of the floating platform's position, attitude and coaxial deviation, a coarse alignment prompt is output to the tugboat or on-site personnel to ensure that the mooring bearing is within the allowable range above the top guide cylinder of the mooring connector; S4.3, Controlled Descent: Water is introduced into the ballast tank of the floating platform to make the floating platform descend at a preset speed. At the same time, the heel, trim, draft, coaxial deviation and tension parameters of each mooring chain of the floating platform are monitored. If any parameter exceeds the allowable range, the descent is suspended or the platform is surfaced to reset. S4.4, Guide engagement: When the coaxial deviation meets the guide engagement condition, reduce the diving speed so that the side guide cylinder of the mooring bearing gradually engages with the top guide cylinder of the mooring connector, and maintain the stability of the platform attitude during the stage of guide bar contact or locating pin hole alignment. S4.5, Flange Fastening: After the guide is engaged, maintain the ballast condition, and the construction personnel complete the installation of the positioning pins, bolts and sealing structure.

5. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 4, characterized in that: The center coordinates of the side guide tubes of the floating platform are as follows: , The center coordinates of the top guide tube of the mooring connector are marked as , ; The angle of the side guide tube axis is denoted as The angle of the axis of the top guide cylinder of the mooring connector is denoted as The tilt angle of a floating platform is denoted as... The tilt angle of the floating platform is denoted as ;No. The anchor chain tension of the root mooring is denoted as The reference tension is denoted as The diving speed of the floating platform is denoted as... ; Coaxial deviation is calculated as follows: ； ； ； ； in, , This refers to the deviation of the centers of the side guide cylinder and the top guide cylinder in the horizontal plane; This refers to the angular deviation between the axes of the side guide cylinder and the top guide cylinder; The sum of squares of the horizontal deviations is used to determine whether entering the guide engagement stage is permitted; During the controlled descent phase, using coaxial deviation, platform attitude, ballast tank level, and anchor chain tension as inputs, the inflow and outflow control parameters for each ballast tank are calculated. The objective function is written as: ； in, The objective function for controlled descent is... to These are the weighting coefficients. To correspond to the reference tension of the mooring anchor chain at this stage, The platform's diving speed; when the coaxial deviation, platform attitude, or mooring anchor chain tension change rate exceeds the preset threshold, ballast water intake is suspended, the current draft is maintained, or the floating platform is controlled to rise to a safe height and then re-aligned. Using the current cycle's water inflow and outflow increment of each ballast tank or ballast tank as the control variable, for m ballast tanks with adjustable water volumes, the current water volume of the k-th ballast tank is V. k The increase in water inflow and outflow during this cycle is ΔV. k Then the control variable is represented as: ; Based on the overall layout of the floating platform, the location of each ballast tank, the flow rate of pumps and valves, and on-site calibration data, a ballast response model is established. The ballast response model is obtained through hydrostatic calculations, tank tests, numerical simulations, or on-site pressure testing and calibration, and is stored in the form of a response coefficient matrix or a lookup table. The simplified expression of the ballast response model is: ； ； in, Forecast response volume for this period; This is the ballast response coefficient matrix; This refers to the change in the platform's draft. For the first The change in tension of the mooring chain; This represents the change in the heel angle of the floating platform. This refers to the change in the pitch angle of the floating platform. Will Substituting the values ​​into the ballast response model, the effects of each candidate inflow / outflow combination on draft, heel, trim, and mooring chain tension are predicted, and a combination that satisfies the constraints and makes... Minimum set of inlet and outlet control quantities ; The constraints are: ； ； in, For the first The maximum allowable water volume for each ballast tank; For the first The maximum flow rate of the pump and valve assembly corresponding to each ballast tank; To control the cycle; , The first The allowable lower and upper limits of tension for root mooring anchor chains; , These are the maximum allowable tilt and longitudinal tilt limits for floating platforms, respectively. The maximum allowable descent speed; when calculated... If the above constraints are exceeded, the inflow and outflow will be executed according to the limited range, and data will be collected and calculated again in the next control cycle.

6. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 1, characterized in that: Six mooring chains are arranged circumferentially in groups of two and three groups. The average tension of each group of mooring chains is calculated, and then the tension deviation between groups and the tension deviation within groups are calculated. The average tension of a group of mooring anchor chains is written as: ； Intergroup tension deviation and intragroup tension deviation are written as follows: ； ； in, For the first The average tension of the two mooring anchor chains. , These are the tensions of the two mooring anchor chains in the j-th group, respectively; Pretension for the target; For the first Inter-group tension deviation of mooring anchor chains; For the first Tension deviation within the mooring chain group; In step S6, when tensioning the mooring anchor chain, the tensioning sequence is output according to the principle of first between groups, then within groups, first low tension, then high tension, and small steps with multiple closed-loop corrections. No. The recommended chain allowance for root mooring anchor chains is written as: ； in, For the first Recommended chain allowance for root mooring anchor chains; , , For control coefficients; A suppression term introduced for the rate of change of tension or the change of platform attitude; Calculate using the following formula: ； in, , , The weight coefficient for the suppression term; For the first Rate of change of anchor chain tension at root mooring; When the tension of a mooring chain changes too rapidly, the tension of adjacent mooring chains is abnormal, or the platform attitude changes beyond the limit, it can lead to... When the tension increases, reduce the recommended chain extension / retraction amount of the mooring anchor chain or suspend tensioning.

7. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 1, characterized in that: After the dynamic submarine cable is laid at the designed location, step S2 is performed on the work vessel: the wind turbine end of the dynamic submarine cable is inserted into the bottom of the mooring connector and then pushed out from the middle upwards, leaving room for the distance to the high-voltage switchgear and the redundant length during normal operation, and coiled on the top of the mooring connector; a hoist is installed on each of the three auxiliary lugs of the mooring connector.

8. The method for single-point mooring of the outer turret of a downwind floating wind turbine as described in claim 1, characterized in that: In step S3, the work vessel lowers the mooring connector with the connected dynamic submarine cable onto the sea surface, then connects the hoists on the three auxiliary lugs of the mooring connector to the ends of the two mooring anchor chains in the corresponding directions, tightens the hoists, and pulls the connecting shackles at the ends of the mooring anchor chains closer to the diver or ROV to install the connecting shackles to the position of the main lugs; when all six mooring anchor chains are connected to the main lugs, slowly loosen the hoists connecting the mooring anchor chains and auxiliary lugs, and remove them after they are completely relaxed.

9. A leeward floating wind turbine external turret suspended single-point mooring system, characterized in that: This includes mooring connectors, mooring anchor chains, off-line buoys, quick couplings, on-line tensioners, connecting shackles, float end connectors, upwind buoys, outer turret platforms, mooring bearings, and outer turret tubes; The mooring connector has main lugs and auxiliary lugs distributed around its periphery, which are used to connect the mooring anchor chain to the mooring connector via a connecting shackle. The top of the mooring connector is provided with a top guide tube. Offline buoys are hollow components with inlet / outlet and outlet / vent, which are connected to mooring chains via quick couplings to provide adjustable buoyancy to the ends of the mooring chains. The floating body end connector is installed on the floating platform. The floating body end connector, the upwind float, the outer turret platform, and the outer turret are connected in sequence to form a whole. The floating body end connector is equipped with a ballast tank. The floating platform can be submerged or floated by filling and dewatering the ballast tank. The upwind float is used to provide stability and restoring torque for the floating platform when the unit is running. The outer ring of the mooring bearing is bolted to the bottom of the outer turret platform and fixed relative to the floating platform. The inner ring can be bolted to the mooring connector. A side guide cylinder is provided at the bottom middle of the mooring bearing. The side guide cylinder and the top guide cylinder are guided by guide strips. Online tensioners are installed on each mooring anchor chain. After the mooring connectors and mooring bearings are connected and installed, the tension of the mooring anchor chains is adjusted by tightening to keep the floating platform on the sea surface.

10. The downwind floating wind turbine external turret suspended single-point mooring system according to claim 9, characterized in that: It also includes a mooring chain tension sensor, a buoy pressure or level detection interface, a coaxial deviation detection unit, a ballast pump valve control unit, and a buoy inlet and outlet control unit; The mooring chain tension sensor is installed near the connection point between the mooring chain and the main lug on the side wall of the mooring connector. It is used to detect the actual tension of each mooring chain at the connection point and to serve as the data source for mooring chain tension balance control. The pressure or level detection interface of the buoy is set on the offline buoy and connected to the temporary pipeline of the work vessel. It is used to detect the internal pressure or level of the offline buoy in order to adjust the buoyancy of the offline buoy. The coaxial deviation detection unit is used to detect the horizontal offset, angular deviation or distance deviation between the guide cylinder of the mooring bearing and the top guide cylinder of the mooring connector. It employs one or more of the following methods: visual recognition, laser ranging, RTK positioning, proximity sensor or mechanical limit detection. Ballast pump valve control unit, used to control the inflow and outflow of ballast tanks according to the target ballast volume; The buoy inlet and outlet control unit is used to perform water intake, drainage, or pressure testing operations on the offline buoy through temporary pipelines or field valve groups on the work vessel.

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